| Message ID | 20230323085226.1432550-10-konstantin.meskhidze@huawei.com |
|---|---|
| State | Handled Elsewhere |
| Delegated to: | Pablo Neira |
| Headers | show |
| Series | Network support for Landlock | expand |
On 23/03/2023 09:52, Konstantin Meskhidze wrote: > This commit adds network rules support in the ruleset management > helpers and the landlock_create_ruleset syscall. > Refactor user space API to support network actions. Add new network > access flags, network rule and network attributes. Increment Landlock > ABI version. Expand access_masks_t to u32 to be sure network access > rights can be stored. Implement socket_bind() and socket_connect() > LSM hooks, which enable to restrict TCP socket binding and connection > to specific ports. > > Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@huawei.com> > --- > > Changes since v9: > * Changes UAPI port field to __u64. > * Moves shared code into check_socket_access(). > * Adds get_raw_handled_net_accesses() and > get_current_net_domain() helpers. > * Minor fixes. > > Changes since v8: > * Squashes commits. > * Refactors commit message. > * Changes UAPI port field to __be16. > * Changes logic of bind/connect hooks with AF_UNSPEC families. > * Adds address length checking. > * Minor fixes. > > Changes since v7: > * Squashes commits. > * Increments ABI version to 4. > * Refactors commit message. > * Minor fixes. > > Changes since v6: > * Renames landlock_set_net_access_mask() to landlock_add_net_access_mask() > because it OR values. > * Makes landlock_add_net_access_mask() more resilient incorrect values. > * Refactors landlock_get_net_access_mask(). > * Renames LANDLOCK_MASK_SHIFT_NET to LANDLOCK_SHIFT_ACCESS_NET and use > LANDLOCK_NUM_ACCESS_FS as value. > * Updates access_masks_t to u32 to support network access actions. > * Refactors landlock internal functions to support network actions with > landlock_key/key_type/id types. > > Changes since v5: > * Gets rid of partial revert from landlock_add_rule > syscall. > * Formats code with clang-format-14. > > Changes since v4: > * Refactors landlock_create_ruleset() - splits ruleset and > masks checks. > * Refactors landlock_create_ruleset() and landlock mask > setters/getters to support two rule types. > * Refactors landlock_add_rule syscall add_rule_path_beneath > function by factoring out get_ruleset_from_fd() and > landlock_put_ruleset(). > > Changes since v3: > * Splits commit. > * Adds network rule support for internal landlock functions. > * Adds set_mask and get_mask for network. > * Adds rb_root root_net_port. > > --- > include/uapi/linux/landlock.h | 49 +++++ > security/landlock/Kconfig | 1 + > security/landlock/Makefile | 2 + > security/landlock/limits.h | 6 +- > security/landlock/net.c | 198 +++++++++++++++++++ > security/landlock/net.h | 26 +++ > security/landlock/ruleset.c | 52 ++++- > security/landlock/ruleset.h | 63 +++++- > security/landlock/setup.c | 2 + > security/landlock/syscalls.c | 72 ++++++- > tools/testing/selftests/landlock/base_test.c | 2 +- > 11 files changed, 450 insertions(+), 23 deletions(-) > create mode 100644 security/landlock/net.c > create mode 100644 security/landlock/net.h [...] > diff --git a/security/landlock/net.c b/security/landlock/net.c [...] > +static int check_addrlen(const struct sockaddr *const address, int addrlen) const int addrlen > +{ > + if (addrlen < offsetofend(struct sockaddr, sa_family)) > + return -EINVAL; > + switch (address->sa_family) { > + case AF_UNSPEC: > + case AF_INET: > + if (addrlen < sizeof(struct sockaddr_in)) > + return -EINVAL; > + return 0; > +#if IS_ENABLED(CONFIG_IPV6) > + case AF_INET6: > + if (addrlen < SIN6_LEN_RFC2133) > + return -EINVAL; > + return 0; > +#endif > + } > + WARN_ON_ONCE(1); > + return 0; > +} > + > +static u16 get_port(const struct sockaddr *const address) > +{ > + /* Gets port value in host byte order. */ > + switch (address->sa_family) { > + case AF_UNSPEC: > + case AF_INET: { > + const struct sockaddr_in *const sockaddr = > + (struct sockaddr_in *)address; > + return ntohs(sockaddr->sin_port); Storing ports in big endian (in rulesets) would avoid converting them every time the kernel checks a socket port. The above comment should then be updated too. > + } > +#if IS_ENABLED(CONFIG_IPV6) > + case AF_INET6: { > + const struct sockaddr_in6 *const sockaddr_ip6 = > + (struct sockaddr_in6 *)address; > + return ntohs(sockaddr_ip6->sin6_port); > + } > +#endif > + } > + WARN_ON_ONCE(1); > + return 0; > +} > + > +static int check_socket_access(struct socket *sock, struct sockaddr *address, int addrlen, u16 port, > + access_mask_t access_request) > +{ > + int ret; > + bool allowed = false; > + layer_mask_t layer_masks[LANDLOCK_NUM_ACCESS_NET] = {}; > + const struct landlock_rule *rule; > + access_mask_t handled_access; > + const struct landlock_id id = { > + .key.data = port, > + .type = LANDLOCK_KEY_NET_PORT, > + }; > + const struct landlock_ruleset *const domain = get_current_net_domain(); > + > + if (WARN_ON_ONCE(!domain)) > + return 0; > + if (WARN_ON_ONCE(domain->num_layers < 1)) > + return -EACCES; > + /* Check if it's a TCP socket. */ > + if (sock->type != SOCK_STREAM) > + return 0; > + > + ret = check_addrlen(address, addrlen); > + if (ret) > + return ret; > + > + switch (address->sa_family) { > + case AF_UNSPEC: > + /* > + * Connecting to an address with AF_UNSPEC dissolves the TCP > + * association, which have the same effect as closing the > + * connection while retaining the socket object (i.e., the file > + * descriptor). As for dropping privileges, closing > + * connections is always allowed. > + */ > + if (access_request == LANDLOCK_ACCESS_NET_CONNECT_TCP) > + return 0; > + > + /* > + * For compatibility reason, accept AF_UNSPEC for bind > + * accesses (mapped to AF_INET) only if the address is > + * INADDR_ANY (cf. __inet_bind). Checking the address is > + * required to not wrongfully return -EACCES instead of > + * -EAFNOSUPPORT. > + */ > + if (access_request == LANDLOCK_ACCESS_NET_BIND_TCP) { > + const struct sockaddr_in *const sockaddr = > + (struct sockaddr_in *)address; > + > + if (sockaddr->sin_addr.s_addr != htonl(INADDR_ANY)) > + return -EAFNOSUPPORT; > + } > + > + fallthrough; > + case AF_INET: > +#if IS_ENABLED(CONFIG_IPV6) > + case AF_INET6: > +#endif > + rule = landlock_find_rule(domain, id); > + handled_access = landlock_init_layer_masks( > + domain, access_request, &layer_masks, > + LANDLOCK_KEY_NET_PORT); > + allowed = landlock_unmask_layers(rule, handled_access, > + &layer_masks, > + ARRAY_SIZE(layer_masks)); > + } > + return allowed ? 0 : -EACCES; > +} > + > +static int hook_socket_bind(struct socket *sock, struct sockaddr *address, > + int addrlen) > +{ > + return check_socket_access(sock, address, addrlen, get_port(address), > + LANDLOCK_ACCESS_NET_BIND_TCP); > +} > + > +static int hook_socket_connect(struct socket *sock, struct sockaddr *address, > + int addrlen) > +{ > + return check_socket_access(sock, address, addrlen, get_port(address), > + LANDLOCK_ACCESS_NET_CONNECT_TCP); > +} [...]
On 31/03/2023 19:24, Mickaël Salaün wrote: > > On 23/03/2023 09:52, Konstantin Meskhidze wrote: >> This commit adds network rules support in the ruleset management >> helpers and the landlock_create_ruleset syscall. >> Refactor user space API to support network actions. Add new network >> access flags, network rule and network attributes. Increment Landlock >> ABI version. Expand access_masks_t to u32 to be sure network access >> rights can be stored. Implement socket_bind() and socket_connect() >> LSM hooks, which enable to restrict TCP socket binding and connection >> to specific ports. >> >> Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@huawei.com> >> --- >> >> Changes since v9: >> * Changes UAPI port field to __u64. >> * Moves shared code into check_socket_access(). >> * Adds get_raw_handled_net_accesses() and >> get_current_net_domain() helpers. >> * Minor fixes. >> >> Changes since v8: >> * Squashes commits. >> * Refactors commit message. >> * Changes UAPI port field to __be16. >> * Changes logic of bind/connect hooks with AF_UNSPEC families. >> * Adds address length checking. >> * Minor fixes. >> >> Changes since v7: >> * Squashes commits. >> * Increments ABI version to 4. >> * Refactors commit message. >> * Minor fixes. >> >> Changes since v6: >> * Renames landlock_set_net_access_mask() to landlock_add_net_access_mask() >> because it OR values. >> * Makes landlock_add_net_access_mask() more resilient incorrect values. >> * Refactors landlock_get_net_access_mask(). >> * Renames LANDLOCK_MASK_SHIFT_NET to LANDLOCK_SHIFT_ACCESS_NET and use >> LANDLOCK_NUM_ACCESS_FS as value. >> * Updates access_masks_t to u32 to support network access actions. >> * Refactors landlock internal functions to support network actions with >> landlock_key/key_type/id types. >> >> Changes since v5: >> * Gets rid of partial revert from landlock_add_rule >> syscall. >> * Formats code with clang-format-14. >> >> Changes since v4: >> * Refactors landlock_create_ruleset() - splits ruleset and >> masks checks. >> * Refactors landlock_create_ruleset() and landlock mask >> setters/getters to support two rule types. >> * Refactors landlock_add_rule syscall add_rule_path_beneath >> function by factoring out get_ruleset_from_fd() and >> landlock_put_ruleset(). >> >> Changes since v3: >> * Splits commit. >> * Adds network rule support for internal landlock functions. >> * Adds set_mask and get_mask for network. >> * Adds rb_root root_net_port. >> >> --- >> include/uapi/linux/landlock.h | 49 +++++ >> security/landlock/Kconfig | 1 + >> security/landlock/Makefile | 2 + >> security/landlock/limits.h | 6 +- >> security/landlock/net.c | 198 +++++++++++++++++++ >> security/landlock/net.h | 26 +++ >> security/landlock/ruleset.c | 52 ++++- >> security/landlock/ruleset.h | 63 +++++- >> security/landlock/setup.c | 2 + >> security/landlock/syscalls.c | 72 ++++++- >> tools/testing/selftests/landlock/base_test.c | 2 +- >> 11 files changed, 450 insertions(+), 23 deletions(-) >> create mode 100644 security/landlock/net.c >> create mode 100644 security/landlock/net.h > > [...] > >> diff --git a/security/landlock/net.c b/security/landlock/net.c > > [...] > >> +static int check_addrlen(const struct sockaddr *const address, int addrlen) > > const int addrlen > >> +{ >> + if (addrlen < offsetofend(struct sockaddr, sa_family)) >> + return -EINVAL; >> + switch (address->sa_family) { >> + case AF_UNSPEC: >> + case AF_INET: >> + if (addrlen < sizeof(struct sockaddr_in)) >> + return -EINVAL; >> + return 0; >> +#if IS_ENABLED(CONFIG_IPV6) >> + case AF_INET6: >> + if (addrlen < SIN6_LEN_RFC2133) >> + return -EINVAL; >> + return 0; >> +#endif >> + } >> + WARN_ON_ONCE(1); >> + return 0; >> +} >> + >> +static u16 get_port(const struct sockaddr *const address) >> +{ >> + /* Gets port value in host byte order. */ >> + switch (address->sa_family) { >> + case AF_UNSPEC: >> + case AF_INET: { >> + const struct sockaddr_in *const sockaddr = >> + (struct sockaddr_in *)address; >> + return ntohs(sockaddr->sin_port); > > Storing ports in big endian (in rulesets) would avoid converting them > every time the kernel checks a socket port. The above comment should > then be updated too. You can then return a __be16 type here and at least also use __be16 in check_socket_access(). > > >> + } >> +#if IS_ENABLED(CONFIG_IPV6) >> + case AF_INET6: { >> + const struct sockaddr_in6 *const sockaddr_ip6 = >> + (struct sockaddr_in6 *)address; >> + return ntohs(sockaddr_ip6->sin6_port); >> + } >> +#endif >> + } >> + WARN_ON_ONCE(1); >> + return 0; >> +} >> + >> +static int check_socket_access(struct socket *sock, struct sockaddr *address, int addrlen, u16 port, >> + access_mask_t access_request) >> +{ >> + int ret; >> + bool allowed = false; >> + layer_mask_t layer_masks[LANDLOCK_NUM_ACCESS_NET] = {}; >> + const struct landlock_rule *rule; >> + access_mask_t handled_access; >> + const struct landlock_id id = { >> + .key.data = port, >> + .type = LANDLOCK_KEY_NET_PORT, >> + }; >> + const struct landlock_ruleset *const domain = get_current_net_domain(); >> + >> + if (WARN_ON_ONCE(!domain)) >> + return 0; >> + if (WARN_ON_ONCE(domain->num_layers < 1)) >> + return -EACCES; >> + /* Check if it's a TCP socket. */ >> + if (sock->type != SOCK_STREAM) >> + return 0; >> + >> + ret = check_addrlen(address, addrlen); >> + if (ret) >> + return ret; >> + >> + switch (address->sa_family) { >> + case AF_UNSPEC: >> + /* >> + * Connecting to an address with AF_UNSPEC dissolves the TCP >> + * association, which have the same effect as closing the >> + * connection while retaining the socket object (i.e., the file >> + * descriptor). As for dropping privileges, closing >> + * connections is always allowed. >> + */ >> + if (access_request == LANDLOCK_ACCESS_NET_CONNECT_TCP) >> + return 0; >> + >> + /* >> + * For compatibility reason, accept AF_UNSPEC for bind >> + * accesses (mapped to AF_INET) only if the address is >> + * INADDR_ANY (cf. __inet_bind). Checking the address is >> + * required to not wrongfully return -EACCES instead of >> + * -EAFNOSUPPORT. >> + */ >> + if (access_request == LANDLOCK_ACCESS_NET_BIND_TCP) { >> + const struct sockaddr_in *const sockaddr = >> + (struct sockaddr_in *)address; >> + >> + if (sockaddr->sin_addr.s_addr != htonl(INADDR_ANY)) >> + return -EAFNOSUPPORT; >> + } >> + >> + fallthrough; >> + case AF_INET: >> +#if IS_ENABLED(CONFIG_IPV6) >> + case AF_INET6: >> +#endif >> + rule = landlock_find_rule(domain, id); >> + handled_access = landlock_init_layer_masks( >> + domain, access_request, &layer_masks, >> + LANDLOCK_KEY_NET_PORT); >> + allowed = landlock_unmask_layers(rule, handled_access, >> + &layer_masks, >> + ARRAY_SIZE(layer_masks)); >> + } >> + return allowed ? 0 : -EACCES; >> +} >> + >> +static int hook_socket_bind(struct socket *sock, struct sockaddr *address, >> + int addrlen) >> +{ >> + return check_socket_access(sock, address, addrlen, get_port(address), >> + LANDLOCK_ACCESS_NET_BIND_TCP); >> +} >> + >> +static int hook_socket_connect(struct socket *sock, struct sockaddr *address, >> + int addrlen) >> +{ >> + return check_socket_access(sock, address, addrlen, get_port(address), >> + LANDLOCK_ACCESS_NET_CONNECT_TCP); >> +} > > [...]
3/31/2023 8:24 PM, Mickaël Salaün пишет: > > On 23/03/2023 09:52, Konstantin Meskhidze wrote: >> This commit adds network rules support in the ruleset management >> helpers and the landlock_create_ruleset syscall. >> Refactor user space API to support network actions. Add new network >> access flags, network rule and network attributes. Increment Landlock >> ABI version. Expand access_masks_t to u32 to be sure network access >> rights can be stored. Implement socket_bind() and socket_connect() >> LSM hooks, which enable to restrict TCP socket binding and connection >> to specific ports. >> >> Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@huawei.com> >> --- >> >> Changes since v9: >> * Changes UAPI port field to __u64. >> * Moves shared code into check_socket_access(). >> * Adds get_raw_handled_net_accesses() and >> get_current_net_domain() helpers. >> * Minor fixes. >> >> Changes since v8: >> * Squashes commits. >> * Refactors commit message. >> * Changes UAPI port field to __be16. >> * Changes logic of bind/connect hooks with AF_UNSPEC families. >> * Adds address length checking. >> * Minor fixes. >> >> Changes since v7: >> * Squashes commits. >> * Increments ABI version to 4. >> * Refactors commit message. >> * Minor fixes. >> >> Changes since v6: >> * Renames landlock_set_net_access_mask() to landlock_add_net_access_mask() >> because it OR values. >> * Makes landlock_add_net_access_mask() more resilient incorrect values. >> * Refactors landlock_get_net_access_mask(). >> * Renames LANDLOCK_MASK_SHIFT_NET to LANDLOCK_SHIFT_ACCESS_NET and use >> LANDLOCK_NUM_ACCESS_FS as value. >> * Updates access_masks_t to u32 to support network access actions. >> * Refactors landlock internal functions to support network actions with >> landlock_key/key_type/id types. >> >> Changes since v5: >> * Gets rid of partial revert from landlock_add_rule >> syscall. >> * Formats code with clang-format-14. >> >> Changes since v4: >> * Refactors landlock_create_ruleset() - splits ruleset and >> masks checks. >> * Refactors landlock_create_ruleset() and landlock mask >> setters/getters to support two rule types. >> * Refactors landlock_add_rule syscall add_rule_path_beneath >> function by factoring out get_ruleset_from_fd() and >> landlock_put_ruleset(). >> >> Changes since v3: >> * Splits commit. >> * Adds network rule support for internal landlock functions. >> * Adds set_mask and get_mask for network. >> * Adds rb_root root_net_port. >> >> --- >> include/uapi/linux/landlock.h | 49 +++++ >> security/landlock/Kconfig | 1 + >> security/landlock/Makefile | 2 + >> security/landlock/limits.h | 6 +- >> security/landlock/net.c | 198 +++++++++++++++++++ >> security/landlock/net.h | 26 +++ >> security/landlock/ruleset.c | 52 ++++- >> security/landlock/ruleset.h | 63 +++++- >> security/landlock/setup.c | 2 + >> security/landlock/syscalls.c | 72 ++++++- >> tools/testing/selftests/landlock/base_test.c | 2 +- >> 11 files changed, 450 insertions(+), 23 deletions(-) >> create mode 100644 security/landlock/net.c >> create mode 100644 security/landlock/net.h > > [...] > >> diff --git a/security/landlock/net.c b/security/landlock/net.c > > [...] > >> +static int check_addrlen(const struct sockaddr *const address, int addrlen) > > const int addrlen Got it. > >> +{ >> + if (addrlen < offsetofend(struct sockaddr, sa_family)) >> + return -EINVAL; >> + switch (address->sa_family) { >> + case AF_UNSPEC: >> + case AF_INET: >> + if (addrlen < sizeof(struct sockaddr_in)) >> + return -EINVAL; >> + return 0; >> +#if IS_ENABLED(CONFIG_IPV6) >> + case AF_INET6: >> + if (addrlen < SIN6_LEN_RFC2133) >> + return -EINVAL; >> + return 0; >> +#endif >> + } >> + WARN_ON_ONCE(1); >> + return 0; >> +} >> + >> +static u16 get_port(const struct sockaddr *const address) >> +{ >> + /* Gets port value in host byte order. */ >> + switch (address->sa_family) { >> + case AF_UNSPEC: >> + case AF_INET: { >> + const struct sockaddr_in *const sockaddr = >> + (struct sockaddr_in *)address; >> + return ntohs(sockaddr->sin_port); > > Storing ports in big endian (in rulesets) would avoid converting them > every time the kernel checks a socket port. The above comment should > then be updated too. I thought we came to a conclusion to stick to host endianess and let kernel do the checks under the hood: https://lore.kernel.org/linux-security-module/278ab07f-7583-a4e0-3d37-1bacd091531d@digikod.net/ Did I misunderstand something? > > >> + } >> +#if IS_ENABLED(CONFIG_IPV6) >> + case AF_INET6: { >> + const struct sockaddr_in6 *const sockaddr_ip6 = >> + (struct sockaddr_in6 *)address; >> + return ntohs(sockaddr_ip6->sin6_port); >> + } >> +#endif >> + } >> + WARN_ON_ONCE(1); >> + return 0; >> +} >> + >> +static int check_socket_access(struct socket *sock, struct sockaddr *address, int addrlen, u16 port, >> + access_mask_t access_request) >> +{ >> + int ret; >> + bool allowed = false; >> + layer_mask_t layer_masks[LANDLOCK_NUM_ACCESS_NET] = {}; >> + const struct landlock_rule *rule; >> + access_mask_t handled_access; >> + const struct landlock_id id = { >> + .key.data = port, >> + .type = LANDLOCK_KEY_NET_PORT, >> + }; >> + const struct landlock_ruleset *const domain = get_current_net_domain(); >> + >> + if (WARN_ON_ONCE(!domain)) >> + return 0; >> + if (WARN_ON_ONCE(domain->num_layers < 1)) >> + return -EACCES; >> + /* Check if it's a TCP socket. */ >> + if (sock->type != SOCK_STREAM) >> + return 0; >> + >> + ret = check_addrlen(address, addrlen); >> + if (ret) >> + return ret; >> + >> + switch (address->sa_family) { >> + case AF_UNSPEC: >> + /* >> + * Connecting to an address with AF_UNSPEC dissolves the TCP >> + * association, which have the same effect as closing the >> + * connection while retaining the socket object (i.e., the file >> + * descriptor). As for dropping privileges, closing >> + * connections is always allowed. >> + */ >> + if (access_request == LANDLOCK_ACCESS_NET_CONNECT_TCP) >> + return 0; >> + >> + /* >> + * For compatibility reason, accept AF_UNSPEC for bind >> + * accesses (mapped to AF_INET) only if the address is >> + * INADDR_ANY (cf. __inet_bind). Checking the address is >> + * required to not wrongfully return -EACCES instead of >> + * -EAFNOSUPPORT. >> + */ >> + if (access_request == LANDLOCK_ACCESS_NET_BIND_TCP) { >> + const struct sockaddr_in *const sockaddr = >> + (struct sockaddr_in *)address; >> + >> + if (sockaddr->sin_addr.s_addr != htonl(INADDR_ANY)) >> + return -EAFNOSUPPORT; >> + } >> + >> + fallthrough; >> + case AF_INET: >> +#if IS_ENABLED(CONFIG_IPV6) >> + case AF_INET6: >> +#endif >> + rule = landlock_find_rule(domain, id); >> + handled_access = landlock_init_layer_masks( >> + domain, access_request, &layer_masks, >> + LANDLOCK_KEY_NET_PORT); >> + allowed = landlock_unmask_layers(rule, handled_access, >> + &layer_masks, >> + ARRAY_SIZE(layer_masks)); >> + } >> + return allowed ? 0 : -EACCES; >> +} >> + >> +static int hook_socket_bind(struct socket *sock, struct sockaddr *address, >> + int addrlen) >> +{ >> + return check_socket_access(sock, address, addrlen, get_port(address), >> + LANDLOCK_ACCESS_NET_BIND_TCP); >> +} >> + >> +static int hook_socket_connect(struct socket *sock, struct sockaddr *address, >> + int addrlen) >> +{ >> + return check_socket_access(sock, address, addrlen, get_port(address), >> + LANDLOCK_ACCESS_NET_CONNECT_TCP); >> +} > > [...] > .
3/31/2023 8:30 PM, Mickaël Salaün пишет: > > On 31/03/2023 19:24, Mickaël Salaün wrote: >> >> On 23/03/2023 09:52, Konstantin Meskhidze wrote: >>> This commit adds network rules support in the ruleset management >>> helpers and the landlock_create_ruleset syscall. >>> Refactor user space API to support network actions. Add new network >>> access flags, network rule and network attributes. Increment Landlock >>> ABI version. Expand access_masks_t to u32 to be sure network access >>> rights can be stored. Implement socket_bind() and socket_connect() >>> LSM hooks, which enable to restrict TCP socket binding and connection >>> to specific ports. >>> >>> Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@huawei.com> >>> --- >>> >>> Changes since v9: >>> * Changes UAPI port field to __u64. >>> * Moves shared code into check_socket_access(). >>> * Adds get_raw_handled_net_accesses() and >>> get_current_net_domain() helpers. >>> * Minor fixes. >>> >>> Changes since v8: >>> * Squashes commits. >>> * Refactors commit message. >>> * Changes UAPI port field to __be16. >>> * Changes logic of bind/connect hooks with AF_UNSPEC families. >>> * Adds address length checking. >>> * Minor fixes. >>> >>> Changes since v7: >>> * Squashes commits. >>> * Increments ABI version to 4. >>> * Refactors commit message. >>> * Minor fixes. >>> >>> Changes since v6: >>> * Renames landlock_set_net_access_mask() to landlock_add_net_access_mask() >>> because it OR values. >>> * Makes landlock_add_net_access_mask() more resilient incorrect values. >>> * Refactors landlock_get_net_access_mask(). >>> * Renames LANDLOCK_MASK_SHIFT_NET to LANDLOCK_SHIFT_ACCESS_NET and use >>> LANDLOCK_NUM_ACCESS_FS as value. >>> * Updates access_masks_t to u32 to support network access actions. >>> * Refactors landlock internal functions to support network actions with >>> landlock_key/key_type/id types. >>> >>> Changes since v5: >>> * Gets rid of partial revert from landlock_add_rule >>> syscall. >>> * Formats code with clang-format-14. >>> >>> Changes since v4: >>> * Refactors landlock_create_ruleset() - splits ruleset and >>> masks checks. >>> * Refactors landlock_create_ruleset() and landlock mask >>> setters/getters to support two rule types. >>> * Refactors landlock_add_rule syscall add_rule_path_beneath >>> function by factoring out get_ruleset_from_fd() and >>> landlock_put_ruleset(). >>> >>> Changes since v3: >>> * Splits commit. >>> * Adds network rule support for internal landlock functions. >>> * Adds set_mask and get_mask for network. >>> * Adds rb_root root_net_port. >>> >>> --- >>> include/uapi/linux/landlock.h | 49 +++++ >>> security/landlock/Kconfig | 1 + >>> security/landlock/Makefile | 2 + >>> security/landlock/limits.h | 6 +- >>> security/landlock/net.c | 198 +++++++++++++++++++ >>> security/landlock/net.h | 26 +++ >>> security/landlock/ruleset.c | 52 ++++- >>> security/landlock/ruleset.h | 63 +++++- >>> security/landlock/setup.c | 2 + >>> security/landlock/syscalls.c | 72 ++++++- >>> tools/testing/selftests/landlock/base_test.c | 2 +- >>> 11 files changed, 450 insertions(+), 23 deletions(-) >>> create mode 100644 security/landlock/net.c >>> create mode 100644 security/landlock/net.h >> >> [...] >> >>> diff --git a/security/landlock/net.c b/security/landlock/net.c >> >> [...] >> >>> +static int check_addrlen(const struct sockaddr *const address, int addrlen) >> >> const int addrlen >> >>> +{ >>> + if (addrlen < offsetofend(struct sockaddr, sa_family)) >>> + return -EINVAL; >>> + switch (address->sa_family) { >>> + case AF_UNSPEC: >>> + case AF_INET: >>> + if (addrlen < sizeof(struct sockaddr_in)) >>> + return -EINVAL; >>> + return 0; >>> +#if IS_ENABLED(CONFIG_IPV6) >>> + case AF_INET6: >>> + if (addrlen < SIN6_LEN_RFC2133) >>> + return -EINVAL; >>> + return 0; >>> +#endif >>> + } >>> + WARN_ON_ONCE(1); >>> + return 0; >>> +} >>> + >>> +static u16 get_port(const struct sockaddr *const address) >>> +{ >>> + /* Gets port value in host byte order. */ >>> + switch (address->sa_family) { >>> + case AF_UNSPEC: >>> + case AF_INET: { >>> + const struct sockaddr_in *const sockaddr = >>> + (struct sockaddr_in *)address; >>> + return ntohs(sockaddr->sin_port); >> >> Storing ports in big endian (in rulesets) would avoid converting them >> every time the kernel checks a socket port. The above comment should >> then be updated too. > > You can then return a __be16 type here and at least also use __be16 in > check_socket_access(). Do you mean we need to do port converting __be16 -> u16 in check_socket_access()??? > >> >> >>> + } >>> +#if IS_ENABLED(CONFIG_IPV6) >>> + case AF_INET6: { >>> + const struct sockaddr_in6 *const sockaddr_ip6 = >>> + (struct sockaddr_in6 *)address; >>> + return ntohs(sockaddr_ip6->sin6_port); >>> + } >>> +#endif >>> + } >>> + WARN_ON_ONCE(1); >>> + return 0; >>> +} >>> + >>> +static int check_socket_access(struct socket *sock, struct sockaddr *address, int addrlen, u16 port, >>> + access_mask_t access_request) >>> +{ >>> + int ret; >>> + bool allowed = false; >>> + layer_mask_t layer_masks[LANDLOCK_NUM_ACCESS_NET] = {}; >>> + const struct landlock_rule *rule; >>> + access_mask_t handled_access; >>> + const struct landlock_id id = { >>> + .key.data = port, >>> + .type = LANDLOCK_KEY_NET_PORT, >>> + }; >>> + const struct landlock_ruleset *const domain = get_current_net_domain(); >>> + >>> + if (WARN_ON_ONCE(!domain)) >>> + return 0; >>> + if (WARN_ON_ONCE(domain->num_layers < 1)) >>> + return -EACCES; >>> + /* Check if it's a TCP socket. */ >>> + if (sock->type != SOCK_STREAM) >>> + return 0; >>> + >>> + ret = check_addrlen(address, addrlen); >>> + if (ret) >>> + return ret; >>> + >>> + switch (address->sa_family) { >>> + case AF_UNSPEC: >>> + /* >>> + * Connecting to an address with AF_UNSPEC dissolves the TCP >>> + * association, which have the same effect as closing the >>> + * connection while retaining the socket object (i.e., the file >>> + * descriptor). As for dropping privileges, closing >>> + * connections is always allowed. >>> + */ >>> + if (access_request == LANDLOCK_ACCESS_NET_CONNECT_TCP) >>> + return 0; >>> + >>> + /* >>> + * For compatibility reason, accept AF_UNSPEC for bind >>> + * accesses (mapped to AF_INET) only if the address is >>> + * INADDR_ANY (cf. __inet_bind). Checking the address is >>> + * required to not wrongfully return -EACCES instead of >>> + * -EAFNOSUPPORT. >>> + */ >>> + if (access_request == LANDLOCK_ACCESS_NET_BIND_TCP) { >>> + const struct sockaddr_in *const sockaddr = >>> + (struct sockaddr_in *)address; >>> + >>> + if (sockaddr->sin_addr.s_addr != htonl(INADDR_ANY)) >>> + return -EAFNOSUPPORT; >>> + } >>> + >>> + fallthrough; >>> + case AF_INET: >>> +#if IS_ENABLED(CONFIG_IPV6) >>> + case AF_INET6: >>> +#endif >>> + rule = landlock_find_rule(domain, id); >>> + handled_access = landlock_init_layer_masks( >>> + domain, access_request, &layer_masks, >>> + LANDLOCK_KEY_NET_PORT); >>> + allowed = landlock_unmask_layers(rule, handled_access, >>> + &layer_masks, >>> + ARRAY_SIZE(layer_masks)); >>> + } >>> + return allowed ? 0 : -EACCES; >>> +} >>> + >>> +static int hook_socket_bind(struct socket *sock, struct sockaddr *address, >>> + int addrlen) >>> +{ >>> + return check_socket_access(sock, address, addrlen, get_port(address), >>> + LANDLOCK_ACCESS_NET_BIND_TCP); >>> +} >>> + >>> +static int hook_socket_connect(struct socket *sock, struct sockaddr *address, >>> + int addrlen) >>> +{ >>> + return check_socket_access(sock, address, addrlen, get_port(address), >>> + LANDLOCK_ACCESS_NET_CONNECT_TCP); >>> +} >> >> [...] > .
On 04/04/2023 11:31, Konstantin Meskhidze (A) wrote: > > > 3/31/2023 8:24 PM, Mickaël Salaün пишет: >> >> On 23/03/2023 09:52, Konstantin Meskhidze wrote: >>> This commit adds network rules support in the ruleset management >>> helpers and the landlock_create_ruleset syscall. >>> Refactor user space API to support network actions. Add new network >>> access flags, network rule and network attributes. Increment Landlock >>> ABI version. Expand access_masks_t to u32 to be sure network access >>> rights can be stored. Implement socket_bind() and socket_connect() >>> LSM hooks, which enable to restrict TCP socket binding and connection >>> to specific ports. >>> >>> Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@huawei.com> >>> --- >>> >>> Changes since v9: >>> * Changes UAPI port field to __u64. >>> * Moves shared code into check_socket_access(). >>> * Adds get_raw_handled_net_accesses() and >>> get_current_net_domain() helpers. >>> * Minor fixes. >>> >>> Changes since v8: >>> * Squashes commits. >>> * Refactors commit message. >>> * Changes UAPI port field to __be16. >>> * Changes logic of bind/connect hooks with AF_UNSPEC families. >>> * Adds address length checking. >>> * Minor fixes. >>> >>> Changes since v7: >>> * Squashes commits. >>> * Increments ABI version to 4. >>> * Refactors commit message. >>> * Minor fixes. >>> >>> Changes since v6: >>> * Renames landlock_set_net_access_mask() to landlock_add_net_access_mask() >>> because it OR values. >>> * Makes landlock_add_net_access_mask() more resilient incorrect values. >>> * Refactors landlock_get_net_access_mask(). >>> * Renames LANDLOCK_MASK_SHIFT_NET to LANDLOCK_SHIFT_ACCESS_NET and use >>> LANDLOCK_NUM_ACCESS_FS as value. >>> * Updates access_masks_t to u32 to support network access actions. >>> * Refactors landlock internal functions to support network actions with >>> landlock_key/key_type/id types. >>> >>> Changes since v5: >>> * Gets rid of partial revert from landlock_add_rule >>> syscall. >>> * Formats code with clang-format-14. >>> >>> Changes since v4: >>> * Refactors landlock_create_ruleset() - splits ruleset and >>> masks checks. >>> * Refactors landlock_create_ruleset() and landlock mask >>> setters/getters to support two rule types. >>> * Refactors landlock_add_rule syscall add_rule_path_beneath >>> function by factoring out get_ruleset_from_fd() and >>> landlock_put_ruleset(). >>> >>> Changes since v3: >>> * Splits commit. >>> * Adds network rule support for internal landlock functions. >>> * Adds set_mask and get_mask for network. >>> * Adds rb_root root_net_port. >>> >>> --- >>> include/uapi/linux/landlock.h | 49 +++++ >>> security/landlock/Kconfig | 1 + >>> security/landlock/Makefile | 2 + >>> security/landlock/limits.h | 6 +- >>> security/landlock/net.c | 198 +++++++++++++++++++ >>> security/landlock/net.h | 26 +++ >>> security/landlock/ruleset.c | 52 ++++- >>> security/landlock/ruleset.h | 63 +++++- >>> security/landlock/setup.c | 2 + >>> security/landlock/syscalls.c | 72 ++++++- >>> tools/testing/selftests/landlock/base_test.c | 2 +- >>> 11 files changed, 450 insertions(+), 23 deletions(-) >>> create mode 100644 security/landlock/net.c >>> create mode 100644 security/landlock/net.h >> >> [...] >> >>> diff --git a/security/landlock/net.c b/security/landlock/net.c >> >> [...] >> >>> +static int check_addrlen(const struct sockaddr *const address, int addrlen) >> >> const int addrlen > > Got it. >> >>> +{ >>> + if (addrlen < offsetofend(struct sockaddr, sa_family)) >>> + return -EINVAL; >>> + switch (address->sa_family) { >>> + case AF_UNSPEC: >>> + case AF_INET: >>> + if (addrlen < sizeof(struct sockaddr_in)) >>> + return -EINVAL; >>> + return 0; >>> +#if IS_ENABLED(CONFIG_IPV6) >>> + case AF_INET6: >>> + if (addrlen < SIN6_LEN_RFC2133) >>> + return -EINVAL; >>> + return 0; >>> +#endif >>> + } >>> + WARN_ON_ONCE(1); >>> + return 0; >>> +} >>> + >>> +static u16 get_port(const struct sockaddr *const address) >>> +{ >>> + /* Gets port value in host byte order. */ >>> + switch (address->sa_family) { >>> + case AF_UNSPEC: >>> + case AF_INET: { >>> + const struct sockaddr_in *const sockaddr = >>> + (struct sockaddr_in *)address; >>> + return ntohs(sockaddr->sin_port); >> >> Storing ports in big endian (in rulesets) would avoid converting them >> every time the kernel checks a socket port. The above comment should >> then be updated too. > > I thought we came to a conclusion to stick to host endianess and > let kernel do the checks under the hood: > https://lore.kernel.org/linux-security-module/278ab07f-7583-a4e0-3d37-1bacd091531d@digikod.net/ > > Did I misunderstand something? We indeed stick to the host endianess for the UAPI/syscalls, but internally the kernel has to do the conversion with as it is currently done by calling ntohs(). To avoid calling ntohs() every time get_port() is called, we can instead only call htons() when creating rules (i.e. one-time htons call instead of multiple ntohs calls). > Do you mean we need to do port converting __be16 -> u16 in > check_socket_access()??? Removing the ntohs() call from get_port() enables to return __be16 instead of u16, and check_socket_access() will then need to use the same type. >> >> >>> + } >>> +#if IS_ENABLED(CONFIG_IPV6) >>> + case AF_INET6: { >>> + const struct sockaddr_in6 *const sockaddr_ip6 = >>> + (struct sockaddr_in6 *)address; >>> + return ntohs(sockaddr_ip6->sin6_port); >>> + } >>> +#endif >>> + } >>> + WARN_ON_ONCE(1); >>> + return 0; >>> +} >>> + >>> +static int check_socket_access(struct socket *sock, struct sockaddr *address, int addrlen, u16 port, >>> + access_mask_t access_request) >>> +{ >>> + int ret; >>> + bool allowed = false; >>> + layer_mask_t layer_masks[LANDLOCK_NUM_ACCESS_NET] = {}; >>> + const struct landlock_rule *rule; >>> + access_mask_t handled_access; >>> + const struct landlock_id id = { >>> + .key.data = port, >>> + .type = LANDLOCK_KEY_NET_PORT, >>> + }; >>> + const struct landlock_ruleset *const domain = get_current_net_domain(); >>> + >>> + if (WARN_ON_ONCE(!domain)) >>> + return 0; >>> + if (WARN_ON_ONCE(domain->num_layers < 1)) >>> + return -EACCES; >>> + /* Check if it's a TCP socket. */ >>> + if (sock->type != SOCK_STREAM) >>> + return 0; >>> + >>> + ret = check_addrlen(address, addrlen); >>> + if (ret) >>> + return ret; >>> + >>> + switch (address->sa_family) { >>> + case AF_UNSPEC: >>> + /* >>> + * Connecting to an address with AF_UNSPEC dissolves the TCP >>> + * association, which have the same effect as closing the >>> + * connection while retaining the socket object (i.e., the file >>> + * descriptor). As for dropping privileges, closing >>> + * connections is always allowed. >>> + */ >>> + if (access_request == LANDLOCK_ACCESS_NET_CONNECT_TCP) >>> + return 0; >>> + >>> + /* >>> + * For compatibility reason, accept AF_UNSPEC for bind >>> + * accesses (mapped to AF_INET) only if the address is >>> + * INADDR_ANY (cf. __inet_bind). Checking the address is >>> + * required to not wrongfully return -EACCES instead of >>> + * -EAFNOSUPPORT. >>> + */ >>> + if (access_request == LANDLOCK_ACCESS_NET_BIND_TCP) { >>> + const struct sockaddr_in *const sockaddr = >>> + (struct sockaddr_in *)address; >>> + >>> + if (sockaddr->sin_addr.s_addr != htonl(INADDR_ANY)) >>> + return -EAFNOSUPPORT; >>> + } >>> + >>> + fallthrough; >>> + case AF_INET: >>> +#if IS_ENABLED(CONFIG_IPV6) >>> + case AF_INET6: >>> +#endif >>> + rule = landlock_find_rule(domain, id); >>> + handled_access = landlock_init_layer_masks( >>> + domain, access_request, &layer_masks, >>> + LANDLOCK_KEY_NET_PORT); >>> + allowed = landlock_unmask_layers(rule, handled_access, >>> + &layer_masks, >>> + ARRAY_SIZE(layer_masks)); >>> + } >>> + return allowed ? 0 : -EACCES; >>> +} >>> + >>> +static int hook_socket_bind(struct socket *sock, struct sockaddr *address, >>> + int addrlen) >>> +{ >>> + return check_socket_access(sock, address, addrlen, get_port(address), >>> + LANDLOCK_ACCESS_NET_BIND_TCP); get_port() is called before check_addrlen(), which is an issue. You'll find attached a patch for these fixes, please squash it in this one for the next version. I'll send other reviews by the end of the week. >>> +} >>> + >>> +static int hook_socket_connect(struct socket *sock, struct sockaddr *address, >>> + int addrlen) >>> +{ >>> + return check_socket_access(sock, address, addrlen, get_port(address), >>> + LANDLOCK_ACCESS_NET_CONNECT_TCP); >>> +} >> >> [...] >> .
On 04/04/2023 18:42, Mickaël Salaün wrote: > > On 04/04/2023 11:31, Konstantin Meskhidze (A) wrote: >> >> >> 3/31/2023 8:24 PM, Mickaël Salaün пишет: >>> >>> On 23/03/2023 09:52, Konstantin Meskhidze wrote: >>>> This commit adds network rules support in the ruleset management >>>> helpers and the landlock_create_ruleset syscall. >>>> Refactor user space API to support network actions. Add new network >>>> access flags, network rule and network attributes. Increment Landlock >>>> ABI version. Expand access_masks_t to u32 to be sure network access >>>> rights can be stored. Implement socket_bind() and socket_connect() >>>> LSM hooks, which enable to restrict TCP socket binding and connection >>>> to specific ports. >>>> >>>> Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@huawei.com> >>>> --- >>>> >>>> Changes since v9: >>>> * Changes UAPI port field to __u64. >>>> * Moves shared code into check_socket_access(). >>>> * Adds get_raw_handled_net_accesses() and >>>> get_current_net_domain() helpers. >>>> * Minor fixes. >>>> >>>> Changes since v8: >>>> * Squashes commits. >>>> * Refactors commit message. >>>> * Changes UAPI port field to __be16. >>>> * Changes logic of bind/connect hooks with AF_UNSPEC families. >>>> * Adds address length checking. >>>> * Minor fixes. >>>> >>>> Changes since v7: >>>> * Squashes commits. >>>> * Increments ABI version to 4. >>>> * Refactors commit message. >>>> * Minor fixes. >>>> >>>> Changes since v6: >>>> * Renames landlock_set_net_access_mask() to landlock_add_net_access_mask() >>>> because it OR values. >>>> * Makes landlock_add_net_access_mask() more resilient incorrect values. >>>> * Refactors landlock_get_net_access_mask(). >>>> * Renames LANDLOCK_MASK_SHIFT_NET to LANDLOCK_SHIFT_ACCESS_NET and use >>>> LANDLOCK_NUM_ACCESS_FS as value. >>>> * Updates access_masks_t to u32 to support network access actions. >>>> * Refactors landlock internal functions to support network actions with >>>> landlock_key/key_type/id types. >>>> >>>> Changes since v5: >>>> * Gets rid of partial revert from landlock_add_rule >>>> syscall. >>>> * Formats code with clang-format-14. >>>> >>>> Changes since v4: >>>> * Refactors landlock_create_ruleset() - splits ruleset and >>>> masks checks. >>>> * Refactors landlock_create_ruleset() and landlock mask >>>> setters/getters to support two rule types. >>>> * Refactors landlock_add_rule syscall add_rule_path_beneath >>>> function by factoring out get_ruleset_from_fd() and >>>> landlock_put_ruleset(). >>>> >>>> Changes since v3: >>>> * Splits commit. >>>> * Adds network rule support for internal landlock functions. >>>> * Adds set_mask and get_mask for network. >>>> * Adds rb_root root_net_port. >>>> >>>> --- >>>> include/uapi/linux/landlock.h | 49 +++++ >>>> security/landlock/Kconfig | 1 + >>>> security/landlock/Makefile | 2 + >>>> security/landlock/limits.h | 6 +- >>>> security/landlock/net.c | 198 +++++++++++++++++++ >>>> security/landlock/net.h | 26 +++ >>>> security/landlock/ruleset.c | 52 ++++- >>>> security/landlock/ruleset.h | 63 +++++- >>>> security/landlock/setup.c | 2 + >>>> security/landlock/syscalls.c | 72 ++++++- >>>> tools/testing/selftests/landlock/base_test.c | 2 +- >>>> 11 files changed, 450 insertions(+), 23 deletions(-) >>>> create mode 100644 security/landlock/net.c >>>> create mode 100644 security/landlock/net.h >>> >>> [...] >>> >>>> diff --git a/security/landlock/net.c b/security/landlock/net.c >>> >>> [...] >>>> +static int check_socket_access(struct socket *sock, struct sockaddr *address, int addrlen, u16 port, >>>> + access_mask_t access_request) >>>> +{ >>>> + int ret; >>>> + bool allowed = false; >>>> + layer_mask_t layer_masks[LANDLOCK_NUM_ACCESS_NET] = {}; >>>> + const struct landlock_rule *rule; >>>> + access_mask_t handled_access; >>>> + const struct landlock_id id = { >>>> + .key.data = port, >>>> + .type = LANDLOCK_KEY_NET_PORT, >>>> + }; >>>> + const struct landlock_ruleset *const domain = get_current_net_domain(); >>>> + >>>> + if (WARN_ON_ONCE(!domain)) >>>> + return 0; >>>> + if (WARN_ON_ONCE(domain->num_layers < 1)) >>>> + return -EACCES; >>>> + /* Check if it's a TCP socket. */ >>>> + if (sock->type != SOCK_STREAM) >>>> + return 0; >>>> + >>>> + ret = check_addrlen(address, addrlen); >>>> + if (ret) >>>> + return ret; >>>> + >>>> + switch (address->sa_family) { >>>> + case AF_UNSPEC: >>>> + /* >>>> + * Connecting to an address with AF_UNSPEC dissolves the TCP >>>> + * association, which have the same effect as closing the >>>> + * connection while retaining the socket object (i.e., the file >>>> + * descriptor). As for dropping privileges, closing >>>> + * connections is always allowed. >>>> + */ >>>> + if (access_request == LANDLOCK_ACCESS_NET_CONNECT_TCP) >>>> + return 0; >>>> + >>>> + /* >>>> + * For compatibility reason, accept AF_UNSPEC for bind >>>> + * accesses (mapped to AF_INET) only if the address is >>>> + * INADDR_ANY (cf. __inet_bind). Checking the address is >>>> + * required to not wrongfully return -EACCES instead of >>>> + * -EAFNOSUPPORT. >>>> + */ >>>> + if (access_request == LANDLOCK_ACCESS_NET_BIND_TCP) { >>>> + const struct sockaddr_in *const sockaddr = >>>> + (struct sockaddr_in *)address; >>>> + >>>> + if (sockaddr->sin_addr.s_addr != htonl(INADDR_ANY)) >>>> + return -EAFNOSUPPORT; >>>> + } >>>> + >>>> + fallthrough; >>>> + case AF_INET: >>>> +#if IS_ENABLED(CONFIG_IPV6) >>>> + case AF_INET6: >>>> +#endif Some more fixes: You can move the port/id.key.data block from my patch here, where it is actually used. >>>> + rule = landlock_find_rule(domain, id); >>>> + handled_access = landlock_init_layer_masks( >>>> + domain, access_request, &layer_masks, >>>> + LANDLOCK_KEY_NET_PORT); >>>> + allowed = landlock_unmask_layers(rule, handled_access, >>>> + &layer_masks, >>>> + ARRAY_SIZE(layer_masks)); The `return allowed ? 0 : -EACCES;` should be here. >>>> + } >>>> + return allowed ? 0 : -EACCES; We should have `return 0;` here. We need a test for an sa_family different than AF_UNSPEC, AF_INET, and AF_INET6 to make sure everything else is allowed (e.g. AF_UNIX with SOCK_STREAM and another test with SOCK_DGRAM). Please make sure this new test will not pass with SOCK_STREAM and the current patch series, but of course it should pass with the next one. >>>> +} >>>> +
4/4/2023 7:42 PM, Mickaël Salaün пишет: > > On 04/04/2023 11:31, Konstantin Meskhidze (A) wrote: >> >> >> 3/31/2023 8:24 PM, Mickaël Salaün пишет: >>> >>> On 23/03/2023 09:52, Konstantin Meskhidze wrote: >>>> This commit adds network rules support in the ruleset management >>>> helpers and the landlock_create_ruleset syscall. >>>> Refactor user space API to support network actions. Add new network >>>> access flags, network rule and network attributes. Increment Landlock >>>> ABI version. Expand access_masks_t to u32 to be sure network access >>>> rights can be stored. Implement socket_bind() and socket_connect() >>>> LSM hooks, which enable to restrict TCP socket binding and connection >>>> to specific ports. >>>> >>>> Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@huawei.com> >>>> --- >>>> >>>> Changes since v9: >>>> * Changes UAPI port field to __u64. >>>> * Moves shared code into check_socket_access(). >>>> * Adds get_raw_handled_net_accesses() and >>>> get_current_net_domain() helpers. >>>> * Minor fixes. >>>> >>>> Changes since v8: >>>> * Squashes commits. >>>> * Refactors commit message. >>>> * Changes UAPI port field to __be16. >>>> * Changes logic of bind/connect hooks with AF_UNSPEC families. >>>> * Adds address length checking. >>>> * Minor fixes. >>>> >>>> Changes since v7: >>>> * Squashes commits. >>>> * Increments ABI version to 4. >>>> * Refactors commit message. >>>> * Minor fixes. >>>> >>>> Changes since v6: >>>> * Renames landlock_set_net_access_mask() to landlock_add_net_access_mask() >>>> because it OR values. >>>> * Makes landlock_add_net_access_mask() more resilient incorrect values. >>>> * Refactors landlock_get_net_access_mask(). >>>> * Renames LANDLOCK_MASK_SHIFT_NET to LANDLOCK_SHIFT_ACCESS_NET and use >>>> LANDLOCK_NUM_ACCESS_FS as value. >>>> * Updates access_masks_t to u32 to support network access actions. >>>> * Refactors landlock internal functions to support network actions with >>>> landlock_key/key_type/id types. >>>> >>>> Changes since v5: >>>> * Gets rid of partial revert from landlock_add_rule >>>> syscall. >>>> * Formats code with clang-format-14. >>>> >>>> Changes since v4: >>>> * Refactors landlock_create_ruleset() - splits ruleset and >>>> masks checks. >>>> * Refactors landlock_create_ruleset() and landlock mask >>>> setters/getters to support two rule types. >>>> * Refactors landlock_add_rule syscall add_rule_path_beneath >>>> function by factoring out get_ruleset_from_fd() and >>>> landlock_put_ruleset(). >>>> >>>> Changes since v3: >>>> * Splits commit. >>>> * Adds network rule support for internal landlock functions. >>>> * Adds set_mask and get_mask for network. >>>> * Adds rb_root root_net_port. >>>> >>>> --- >>>> include/uapi/linux/landlock.h | 49 +++++ >>>> security/landlock/Kconfig | 1 + >>>> security/landlock/Makefile | 2 + >>>> security/landlock/limits.h | 6 +- >>>> security/landlock/net.c | 198 +++++++++++++++++++ >>>> security/landlock/net.h | 26 +++ >>>> security/landlock/ruleset.c | 52 ++++- >>>> security/landlock/ruleset.h | 63 +++++- >>>> security/landlock/setup.c | 2 + >>>> security/landlock/syscalls.c | 72 ++++++- >>>> tools/testing/selftests/landlock/base_test.c | 2 +- >>>> 11 files changed, 450 insertions(+), 23 deletions(-) >>>> create mode 100644 security/landlock/net.c >>>> create mode 100644 security/landlock/net.h >>> >>> [...] >>> >>>> diff --git a/security/landlock/net.c b/security/landlock/net.c >>> >>> [...] >>> >>>> +static int check_addrlen(const struct sockaddr *const address, int addrlen) >>> >>> const int addrlen >> >> Got it. >>> >>>> +{ >>>> + if (addrlen < offsetofend(struct sockaddr, sa_family)) >>>> + return -EINVAL; >>>> + switch (address->sa_family) { >>>> + case AF_UNSPEC: >>>> + case AF_INET: >>>> + if (addrlen < sizeof(struct sockaddr_in)) >>>> + return -EINVAL; >>>> + return 0; >>>> +#if IS_ENABLED(CONFIG_IPV6) >>>> + case AF_INET6: >>>> + if (addrlen < SIN6_LEN_RFC2133) >>>> + return -EINVAL; >>>> + return 0; >>>> +#endif >>>> + } >>>> + WARN_ON_ONCE(1); >>>> + return 0; >>>> +} >>>> + >>>> +static u16 get_port(const struct sockaddr *const address) >>>> +{ >>>> + /* Gets port value in host byte order. */ >>>> + switch (address->sa_family) { >>>> + case AF_UNSPEC: >>>> + case AF_INET: { >>>> + const struct sockaddr_in *const sockaddr = >>>> + (struct sockaddr_in *)address; >>>> + return ntohs(sockaddr->sin_port); >>> >>> Storing ports in big endian (in rulesets) would avoid converting them >>> every time the kernel checks a socket port. The above comment should >>> then be updated too. >> >> I thought we came to a conclusion to stick to host endianess and >> let kernel do the checks under the hood: >> https://lore.kernel.org/linux-security-module/278ab07f-7583-a4e0-3d37-1bacd091531d@digikod.net/ >> >> Did I misunderstand something? > > We indeed stick to the host endianess for the UAPI/syscalls, but > internally the kernel has to do the conversion with as it is currently > done by calling ntohs(). To avoid calling ntohs() every time get_port() > is called, we can instead only call htons() when creating rules (i.e. > one-time htons call instead of multiple ntohs calls). > Do you mean we need to covert port in landlock_append_net_rule(): ... int err; const struct landlock_id id = { .key.data = ntohs(port), .type = LANDLOCK_KEY_NET_PORT, }; BUILD_BUG_ON(sizeof(port) > sizeof(id.key.data)); ... ???? > >> Do you mean we need to do port converting __be16 -> u16 in >> check_socket_access()??? > > Removing the ntohs() call from get_port() enables to return __be16 > instead of u16, and check_socket_access() will then need to use the same > type. Ok. I got it. Thanks. > > >>> >>> >>>> + } >>>> +#if IS_ENABLED(CONFIG_IPV6) >>>> + case AF_INET6: { >>>> + const struct sockaddr_in6 *const sockaddr_ip6 = >>>> + (struct sockaddr_in6 *)address; >>>> + return ntohs(sockaddr_ip6->sin6_port); >>>> + } >>>> +#endif >>>> + } >>>> + WARN_ON_ONCE(1); >>>> + return 0; >>>> +} >>>> + >>>> +static int check_socket_access(struct socket *sock, struct sockaddr *address, int addrlen, u16 port, >>>> + access_mask_t access_request) >>>> +{ >>>> + int ret; >>>> + bool allowed = false; >>>> + layer_mask_t layer_masks[LANDLOCK_NUM_ACCESS_NET] = {}; >>>> + const struct landlock_rule *rule; >>>> + access_mask_t handled_access; >>>> + const struct landlock_id id = { >>>> + .key.data = port, >>>> + .type = LANDLOCK_KEY_NET_PORT, >>>> + }; >>>> + const struct landlock_ruleset *const domain = get_current_net_domain(); >>>> + >>>> + if (WARN_ON_ONCE(!domain)) >>>> + return 0; >>>> + if (WARN_ON_ONCE(domain->num_layers < 1)) >>>> + return -EACCES; >>>> + /* Check if it's a TCP socket. */ >>>> + if (sock->type != SOCK_STREAM) >>>> + return 0; >>>> + >>>> + ret = check_addrlen(address, addrlen); >>>> + if (ret) >>>> + return ret; >>>> + >>>> + switch (address->sa_family) { >>>> + case AF_UNSPEC: >>>> + /* >>>> + * Connecting to an address with AF_UNSPEC dissolves the TCP >>>> + * association, which have the same effect as closing the >>>> + * connection while retaining the socket object (i.e., the file >>>> + * descriptor). As for dropping privileges, closing >>>> + * connections is always allowed. >>>> + */ >>>> + if (access_request == LANDLOCK_ACCESS_NET_CONNECT_TCP) >>>> + return 0; >>>> + >>>> + /* >>>> + * For compatibility reason, accept AF_UNSPEC for bind >>>> + * accesses (mapped to AF_INET) only if the address is >>>> + * INADDR_ANY (cf. __inet_bind). Checking the address is >>>> + * required to not wrongfully return -EACCES instead of >>>> + * -EAFNOSUPPORT. >>>> + */ >>>> + if (access_request == LANDLOCK_ACCESS_NET_BIND_TCP) { >>>> + const struct sockaddr_in *const sockaddr = >>>> + (struct sockaddr_in *)address; >>>> + >>>> + if (sockaddr->sin_addr.s_addr != htonl(INADDR_ANY)) >>>> + return -EAFNOSUPPORT; >>>> + } >>>> + >>>> + fallthrough; >>>> + case AF_INET: >>>> +#if IS_ENABLED(CONFIG_IPV6) >>>> + case AF_INET6: >>>> +#endif >>>> + rule = landlock_find_rule(domain, id); >>>> + handled_access = landlock_init_layer_masks( >>>> + domain, access_request, &layer_masks, >>>> + LANDLOCK_KEY_NET_PORT); >>>> + allowed = landlock_unmask_layers(rule, handled_access, >>>> + &layer_masks, >>>> + ARRAY_SIZE(layer_masks)); >>>> + } >>>> + return allowed ? 0 : -EACCES; >>>> +} >>>> + >>>> +static int hook_socket_bind(struct socket *sock, struct sockaddr *address, >>>> + int addrlen) >>>> +{ >>> + return check_socket_access(sock, address, addrlen, get_port(address), >>>> + LANDLOCK_ACCESS_NET_BIND_TCP); > > get_port() is called before check_addrlen(), which is an issue. > > You'll find attached a patch for these fixes, please squash it in this > one for the next version. > > I'll send other reviews by the end of the week. > > >>>> +} >>>> + >>>> +static int hook_socket_connect(struct socket *sock, struct sockaddr *address, >>>> + int addrlen) >>>> +{ >>>> + return check_socket_access(sock, address, addrlen, get_port(address), >>>> + LANDLOCK_ACCESS_NET_CONNECT_TCP); >>>> +} >>> >>> [...] >>> .
4/4/2023 8:02 PM, Mickaël Salaün пишет: > > On 04/04/2023 18:42, Mickaël Salaün wrote: >> >> On 04/04/2023 11:31, Konstantin Meskhidze (A) wrote: >>> >>> >>> 3/31/2023 8:24 PM, Mickaël Salaün пишет: >>>> >>>> On 23/03/2023 09:52, Konstantin Meskhidze wrote: >>>>> This commit adds network rules support in the ruleset management >>>>> helpers and the landlock_create_ruleset syscall. >>>>> Refactor user space API to support network actions. Add new network >>>>> access flags, network rule and network attributes. Increment Landlock >>>>> ABI version. Expand access_masks_t to u32 to be sure network access >>>>> rights can be stored. Implement socket_bind() and socket_connect() >>>>> LSM hooks, which enable to restrict TCP socket binding and connection >>>>> to specific ports. >>>>> >>>>> Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@huawei.com> >>>>> --- >>>>> >>>>> Changes since v9: >>>>> * Changes UAPI port field to __u64. >>>>> * Moves shared code into check_socket_access(). >>>>> * Adds get_raw_handled_net_accesses() and >>>>> get_current_net_domain() helpers. >>>>> * Minor fixes. >>>>> >>>>> Changes since v8: >>>>> * Squashes commits. >>>>> * Refactors commit message. >>>>> * Changes UAPI port field to __be16. >>>>> * Changes logic of bind/connect hooks with AF_UNSPEC families. >>>>> * Adds address length checking. >>>>> * Minor fixes. >>>>> >>>>> Changes since v7: >>>>> * Squashes commits. >>>>> * Increments ABI version to 4. >>>>> * Refactors commit message. >>>>> * Minor fixes. >>>>> >>>>> Changes since v6: >>>>> * Renames landlock_set_net_access_mask() to landlock_add_net_access_mask() >>>>> because it OR values. >>>>> * Makes landlock_add_net_access_mask() more resilient incorrect values. >>>>> * Refactors landlock_get_net_access_mask(). >>>>> * Renames LANDLOCK_MASK_SHIFT_NET to LANDLOCK_SHIFT_ACCESS_NET and use >>>>> LANDLOCK_NUM_ACCESS_FS as value. >>>>> * Updates access_masks_t to u32 to support network access actions. >>>>> * Refactors landlock internal functions to support network actions with >>>>> landlock_key/key_type/id types. >>>>> >>>>> Changes since v5: >>>>> * Gets rid of partial revert from landlock_add_rule >>>>> syscall. >>>>> * Formats code with clang-format-14. >>>>> >>>>> Changes since v4: >>>>> * Refactors landlock_create_ruleset() - splits ruleset and >>>>> masks checks. >>>>> * Refactors landlock_create_ruleset() and landlock mask >>>>> setters/getters to support two rule types. >>>>> * Refactors landlock_add_rule syscall add_rule_path_beneath >>>>> function by factoring out get_ruleset_from_fd() and >>>>> landlock_put_ruleset(). >>>>> >>>>> Changes since v3: >>>>> * Splits commit. >>>>> * Adds network rule support for internal landlock functions. >>>>> * Adds set_mask and get_mask for network. >>>>> * Adds rb_root root_net_port. >>>>> >>>>> --- >>>>> include/uapi/linux/landlock.h | 49 +++++ >>>>> security/landlock/Kconfig | 1 + >>>>> security/landlock/Makefile | 2 + >>>>> security/landlock/limits.h | 6 +- >>>>> security/landlock/net.c | 198 +++++++++++++++++++ >>>>> security/landlock/net.h | 26 +++ >>>>> security/landlock/ruleset.c | 52 ++++- >>>>> security/landlock/ruleset.h | 63 +++++- >>>>> security/landlock/setup.c | 2 + >>>>> security/landlock/syscalls.c | 72 ++++++- >>>>> tools/testing/selftests/landlock/base_test.c | 2 +- >>>>> 11 files changed, 450 insertions(+), 23 deletions(-) >>>>> create mode 100644 security/landlock/net.c >>>>> create mode 100644 security/landlock/net.h >>>> >>>> [...] >>>> >>>>> diff --git a/security/landlock/net.c b/security/landlock/net.c >>>> >>>> [...] > > >>>>> +static int check_socket_access(struct socket *sock, struct sockaddr *address, int addrlen, u16 port, >>>>> + access_mask_t access_request) >>>>> +{ >>>>> + int ret; >>>>> + bool allowed = false; >>>>> + layer_mask_t layer_masks[LANDLOCK_NUM_ACCESS_NET] = {}; >>>>> + const struct landlock_rule *rule; >>>>> + access_mask_t handled_access; >>>>> + const struct landlock_id id = { >>>>> + .key.data = port, >>>>> + .type = LANDLOCK_KEY_NET_PORT, >>>>> + }; >>>>> + const struct landlock_ruleset *const domain = get_current_net_domain(); >>>>> + >>>>> + if (WARN_ON_ONCE(!domain)) >>>>> + return 0; >>>>> + if (WARN_ON_ONCE(domain->num_layers < 1)) >>>>> + return -EACCES; >>>>> + /* Check if it's a TCP socket. */ >>>>> + if (sock->type != SOCK_STREAM) >>>>> + return 0; >>>>> + >>>>> + ret = check_addrlen(address, addrlen); >>>>> + if (ret) >>>>> + return ret; >>>>> + >>>>> + switch (address->sa_family) { >>>>> + case AF_UNSPEC: >>>>> + /* >>>>> + * Connecting to an address with AF_UNSPEC dissolves the TCP >>>>> + * association, which have the same effect as closing the >>>>> + * connection while retaining the socket object (i.e., the file >>>>> + * descriptor). As for dropping privileges, closing >>>>> + * connections is always allowed. >>>>> + */ >>>>> + if (access_request == LANDLOCK_ACCESS_NET_CONNECT_TCP) >>>>> + return 0; >>>>> + >>>>> + /* >>>>> + * For compatibility reason, accept AF_UNSPEC for bind >>>>> + * accesses (mapped to AF_INET) only if the address is >>>>> + * INADDR_ANY (cf. __inet_bind). Checking the address is >>>>> + * required to not wrongfully return -EACCES instead of >>>>> + * -EAFNOSUPPORT. >>>>> + */ >>>>> + if (access_request == LANDLOCK_ACCESS_NET_BIND_TCP) { >>>>> + const struct sockaddr_in *const sockaddr = >>>>> + (struct sockaddr_in *)address; >>>>> + >>>>> + if (sockaddr->sin_addr.s_addr != htonl(INADDR_ANY)) >>>>> + return -EAFNOSUPPORT; >>>>> + } >>>>> + >>>>> + fallthrough; >>>>> + case AF_INET: >>>>> +#if IS_ENABLED(CONFIG_IPV6) >>>>> + case AF_INET6: >>>>> +#endif > > Some more fixes: > > You can move the port/id.key.data block from my patch here, where it is > actually used. > Ok. Thank you. I will apply it. > >>>>> + rule = landlock_find_rule(domain, id); >>>>> + handled_access = landlock_init_layer_masks( >>>>> + domain, access_request, &layer_masks, >>>>> + LANDLOCK_KEY_NET_PORT); >>>>> + allowed = landlock_unmask_layers(rule, handled_access, >>>>> + &layer_masks, >>>>> + ARRAY_SIZE(layer_masks)); > > The `return allowed ? 0 : -EACCES;` should be here. > >>>>> + } >>>>> + return allowed ? 0 : -EACCES; > > We should have `return 0;` here. > Got it. Thanks > We need a test for an sa_family different than AF_UNSPEC, AF_INET, and > AF_INET6 to make sure everything else is allowed (e.g. AF_UNIX with > SOCK_STREAM and another test with SOCK_DGRAM). Please make sure this new > test will not pass with SOCK_STREAM and the current patch series, but of > course it should pass with the next one. Do you mean AF_UNIX with SOCK_STREAM will not be passed as well as AF_UNIX with SOCK_DGRAM? > > >>>>> +} >>>>> + > .
On 05/04/2023 19:42, Konstantin Meskhidze (A) wrote: > > > 4/4/2023 7:42 PM, Mickaël Salaün пишет: >> >> On 04/04/2023 11:31, Konstantin Meskhidze (A) wrote: >>> >>> >>> 3/31/2023 8:24 PM, Mickaël Salaün пишет: >>>> >>>> On 23/03/2023 09:52, Konstantin Meskhidze wrote: >>>>> This commit adds network rules support in the ruleset management >>>>> helpers and the landlock_create_ruleset syscall. >>>>> Refactor user space API to support network actions. Add new network >>>>> access flags, network rule and network attributes. Increment Landlock >>>>> ABI version. Expand access_masks_t to u32 to be sure network access >>>>> rights can be stored. Implement socket_bind() and socket_connect() >>>>> LSM hooks, which enable to restrict TCP socket binding and connection >>>>> to specific ports. >>>>> >>>>> Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@huawei.com> >>>>> --- >>>>> >>>>> Changes since v9: >>>>> * Changes UAPI port field to __u64. >>>>> * Moves shared code into check_socket_access(). >>>>> * Adds get_raw_handled_net_accesses() and >>>>> get_current_net_domain() helpers. >>>>> * Minor fixes. >>>>> >>>>> Changes since v8: >>>>> * Squashes commits. >>>>> * Refactors commit message. >>>>> * Changes UAPI port field to __be16. >>>>> * Changes logic of bind/connect hooks with AF_UNSPEC families. >>>>> * Adds address length checking. >>>>> * Minor fixes. >>>>> >>>>> Changes since v7: >>>>> * Squashes commits. >>>>> * Increments ABI version to 4. >>>>> * Refactors commit message. >>>>> * Minor fixes. >>>>> >>>>> Changes since v6: >>>>> * Renames landlock_set_net_access_mask() to landlock_add_net_access_mask() >>>>> because it OR values. >>>>> * Makes landlock_add_net_access_mask() more resilient incorrect values. >>>>> * Refactors landlock_get_net_access_mask(). >>>>> * Renames LANDLOCK_MASK_SHIFT_NET to LANDLOCK_SHIFT_ACCESS_NET and use >>>>> LANDLOCK_NUM_ACCESS_FS as value. >>>>> * Updates access_masks_t to u32 to support network access actions. >>>>> * Refactors landlock internal functions to support network actions with >>>>> landlock_key/key_type/id types. >>>>> >>>>> Changes since v5: >>>>> * Gets rid of partial revert from landlock_add_rule >>>>> syscall. >>>>> * Formats code with clang-format-14. >>>>> >>>>> Changes since v4: >>>>> * Refactors landlock_create_ruleset() - splits ruleset and >>>>> masks checks. >>>>> * Refactors landlock_create_ruleset() and landlock mask >>>>> setters/getters to support two rule types. >>>>> * Refactors landlock_add_rule syscall add_rule_path_beneath >>>>> function by factoring out get_ruleset_from_fd() and >>>>> landlock_put_ruleset(). >>>>> >>>>> Changes since v3: >>>>> * Splits commit. >>>>> * Adds network rule support for internal landlock functions. >>>>> * Adds set_mask and get_mask for network. >>>>> * Adds rb_root root_net_port. >>>>> >>>>> --- >>>>> include/uapi/linux/landlock.h | 49 +++++ >>>>> security/landlock/Kconfig | 1 + >>>>> security/landlock/Makefile | 2 + >>>>> security/landlock/limits.h | 6 +- >>>>> security/landlock/net.c | 198 +++++++++++++++++++ >>>>> security/landlock/net.h | 26 +++ >>>>> security/landlock/ruleset.c | 52 ++++- >>>>> security/landlock/ruleset.h | 63 +++++- >>>>> security/landlock/setup.c | 2 + >>>>> security/landlock/syscalls.c | 72 ++++++- >>>>> tools/testing/selftests/landlock/base_test.c | 2 +- >>>>> 11 files changed, 450 insertions(+), 23 deletions(-) >>>>> create mode 100644 security/landlock/net.c >>>>> create mode 100644 security/landlock/net.h >>>> >>>> [...] >>>> >>>>> diff --git a/security/landlock/net.c b/security/landlock/net.c >>>> >>>> [...] >>>> >>>>> +static int check_addrlen(const struct sockaddr *const address, int addrlen) >>>> >>>> const int addrlen >>> >>> Got it. >>>> >>>>> +{ >>>>> + if (addrlen < offsetofend(struct sockaddr, sa_family)) >>>>> + return -EINVAL; >>>>> + switch (address->sa_family) { >>>>> + case AF_UNSPEC: >>>>> + case AF_INET: >>>>> + if (addrlen < sizeof(struct sockaddr_in)) >>>>> + return -EINVAL; >>>>> + return 0; >>>>> +#if IS_ENABLED(CONFIG_IPV6) >>>>> + case AF_INET6: >>>>> + if (addrlen < SIN6_LEN_RFC2133) >>>>> + return -EINVAL; >>>>> + return 0; >>>>> +#endif >>>>> + } >>>>> + WARN_ON_ONCE(1); >>>>> + return 0; >>>>> +} >>>>> + >>>>> +static u16 get_port(const struct sockaddr *const address) >>>>> +{ >>>>> + /* Gets port value in host byte order. */ >>>>> + switch (address->sa_family) { >>>>> + case AF_UNSPEC: >>>>> + case AF_INET: { >>>>> + const struct sockaddr_in *const sockaddr = >>>>> + (struct sockaddr_in *)address; >>>>> + return ntohs(sockaddr->sin_port); >>>> >>>> Storing ports in big endian (in rulesets) would avoid converting them >>>> every time the kernel checks a socket port. The above comment should >>>> then be updated too. >>> >>> I thought we came to a conclusion to stick to host endianess and >>> let kernel do the checks under the hood: >>> https://lore.kernel.org/linux-security-module/278ab07f-7583-a4e0-3d37-1bacd091531d@digikod.net/ >>> >>> Did I misunderstand something? >> >> We indeed stick to the host endianess for the UAPI/syscalls, but >> internally the kernel has to do the conversion with as it is currently >> done by calling ntohs(). To avoid calling ntohs() every time get_port() >> is called, we can instead only call htons() when creating rules (i.e. >> one-time htons call instead of multiple ntohs calls). >> > Do you mean we need to covert port in landlock_append_net_rule(): > > ... > > int err; > const struct landlock_id id = { > .key.data = ntohs(port), > .type = LANDLOCK_KEY_NET_PORT, > }; > BUILD_BUG_ON(sizeof(port) > sizeof(id.key.data)); > ... > ???? landlock_append_net_rule() takes a u16 (host endianess, which is the case with this patch series) and should store a big endian 16-bit integer. See my patch: const struct landlock_id id = { - .key.data = port, + .key.data = (__force uintptr_t)htons(port), .type = LANDLOCK_KEY_NET_PORT, }; >> >>> Do you mean we need to do port converting __be16 -> u16 in >>> check_socket_access()??? >> >> Removing the ntohs() call from get_port() enables to return __be16 >> instead of u16, and check_socket_access() will then need to use the same >> type. > > Ok. I got it. Thanks. >> >> >>>> >>>> >>>>> + } >>>>> +#if IS_ENABLED(CONFIG_IPV6) >>>>> + case AF_INET6: { >>>>> + const struct sockaddr_in6 *const sockaddr_ip6 = >>>>> + (struct sockaddr_in6 *)address; >>>>> + return ntohs(sockaddr_ip6->sin6_port); >>>>> + } >>>>> +#endif >>>>> + } >>>>> + WARN_ON_ONCE(1); >>>>> + return 0; >>>>> +} >>>>> + >>>>> +static int check_socket_access(struct socket *sock, struct sockaddr *address, int addrlen, u16 port, >>>>> + access_mask_t access_request) >>>>> +{ >>>>> + int ret; >>>>> + bool allowed = false; >>>>> + layer_mask_t layer_masks[LANDLOCK_NUM_ACCESS_NET] = {}; >>>>> + const struct landlock_rule *rule; >>>>> + access_mask_t handled_access; >>>>> + const struct landlock_id id = { >>>>> + .key.data = port, >>>>> + .type = LANDLOCK_KEY_NET_PORT, >>>>> + }; >>>>> + const struct landlock_ruleset *const domain = get_current_net_domain(); >>>>> + >>>>> + if (WARN_ON_ONCE(!domain)) >>>>> + return 0; >>>>> + if (WARN_ON_ONCE(domain->num_layers < 1)) >>>>> + return -EACCES; >>>>> + /* Check if it's a TCP socket. */ >>>>> + if (sock->type != SOCK_STREAM) >>>>> + return 0; >>>>> + >>>>> + ret = check_addrlen(address, addrlen); >>>>> + if (ret) >>>>> + return ret; >>>>> + >>>>> + switch (address->sa_family) { >>>>> + case AF_UNSPEC: >>>>> + /* >>>>> + * Connecting to an address with AF_UNSPEC dissolves the TCP >>>>> + * association, which have the same effect as closing the >>>>> + * connection while retaining the socket object (i.e., the file >>>>> + * descriptor). As for dropping privileges, closing >>>>> + * connections is always allowed. >>>>> + */ >>>>> + if (access_request == LANDLOCK_ACCESS_NET_CONNECT_TCP) >>>>> + return 0; >>>>> + >>>>> + /* >>>>> + * For compatibility reason, accept AF_UNSPEC for bind >>>>> + * accesses (mapped to AF_INET) only if the address is >>>>> + * INADDR_ANY (cf. __inet_bind). Checking the address is >>>>> + * required to not wrongfully return -EACCES instead of >>>>> + * -EAFNOSUPPORT. >>>>> + */ >>>>> + if (access_request == LANDLOCK_ACCESS_NET_BIND_TCP) { >>>>> + const struct sockaddr_in *const sockaddr = >>>>> + (struct sockaddr_in *)address; >>>>> + >>>>> + if (sockaddr->sin_addr.s_addr != htonl(INADDR_ANY)) >>>>> + return -EAFNOSUPPORT; >>>>> + } >>>>> + >>>>> + fallthrough; >>>>> + case AF_INET: >>>>> +#if IS_ENABLED(CONFIG_IPV6) >>>>> + case AF_INET6: >>>>> +#endif >>>>> + rule = landlock_find_rule(domain, id); >>>>> + handled_access = landlock_init_layer_masks( >>>>> + domain, access_request, &layer_masks, >>>>> + LANDLOCK_KEY_NET_PORT); >>>>> + allowed = landlock_unmask_layers(rule, handled_access, >>>>> + &layer_masks, >>>>> + ARRAY_SIZE(layer_masks)); >>>>> + } >>>>> + return allowed ? 0 : -EACCES; >>>>> +} >>>>> + >>>>> +static int hook_socket_bind(struct socket *sock, struct sockaddr *address, >>>>> + int addrlen) >>>>> +{ >>> + return check_socket_access(sock, address, addrlen, get_port(address), >>>>> + LANDLOCK_ACCESS_NET_BIND_TCP); >> >> get_port() is called before check_addrlen(), which is an issue. >> >> You'll find attached a patch for these fixes, please squash it in this >> one for the next version. >> >> I'll send other reviews by the end of the week. >> >> >>>>> +} >>>>> + >>>>> +static int hook_socket_connect(struct socket *sock, struct sockaddr *address, >>>>> + int addrlen) >>>>> +{ >>>>> + return check_socket_access(sock, address, addrlen, get_port(address), >>>>> + LANDLOCK_ACCESS_NET_CONNECT_TCP); >>>>> +} >>>> >>>> [...] >>>> .
4/6/2023 1:28 PM, Mickaël Salaün пишет: > > On 05/04/2023 19:42, Konstantin Meskhidze (A) wrote: >> >> >> 4/4/2023 7:42 PM, Mickaël Salaün пишет: >>> >>> On 04/04/2023 11:31, Konstantin Meskhidze (A) wrote: >>>> >>>> >>>> 3/31/2023 8:24 PM, Mickaël Salaün пишет: >>>>> >>>>> On 23/03/2023 09:52, Konstantin Meskhidze wrote: >>>>>> This commit adds network rules support in the ruleset management >>>>>> helpers and the landlock_create_ruleset syscall. >>>>>> Refactor user space API to support network actions. Add new network >>>>>> access flags, network rule and network attributes. Increment Landlock >>>>>> ABI version. Expand access_masks_t to u32 to be sure network access >>>>>> rights can be stored. Implement socket_bind() and socket_connect() >>>>>> LSM hooks, which enable to restrict TCP socket binding and connection >>>>>> to specific ports. >>>>>> >>>>>> Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@huawei.com> >>>>>> --- >>>>>> >>>>>> Changes since v9: >>>>>> * Changes UAPI port field to __u64. >>>>>> * Moves shared code into check_socket_access(). >>>>>> * Adds get_raw_handled_net_accesses() and >>>>>> get_current_net_domain() helpers. >>>>>> * Minor fixes. >>>>>> >>>>>> Changes since v8: >>>>>> * Squashes commits. >>>>>> * Refactors commit message. >>>>>> * Changes UAPI port field to __be16. >>>>>> * Changes logic of bind/connect hooks with AF_UNSPEC families. >>>>>> * Adds address length checking. >>>>>> * Minor fixes. >>>>>> >>>>>> Changes since v7: >>>>>> * Squashes commits. >>>>>> * Increments ABI version to 4. >>>>>> * Refactors commit message. >>>>>> * Minor fixes. >>>>>> >>>>>> Changes since v6: >>>>>> * Renames landlock_set_net_access_mask() to landlock_add_net_access_mask() >>>>>> because it OR values. >>>>>> * Makes landlock_add_net_access_mask() more resilient incorrect values. >>>>>> * Refactors landlock_get_net_access_mask(). >>>>>> * Renames LANDLOCK_MASK_SHIFT_NET to LANDLOCK_SHIFT_ACCESS_NET and use >>>>>> LANDLOCK_NUM_ACCESS_FS as value. >>>>>> * Updates access_masks_t to u32 to support network access actions. >>>>>> * Refactors landlock internal functions to support network actions with >>>>>> landlock_key/key_type/id types. >>>>>> >>>>>> Changes since v5: >>>>>> * Gets rid of partial revert from landlock_add_rule >>>>>> syscall. >>>>>> * Formats code with clang-format-14. >>>>>> >>>>>> Changes since v4: >>>>>> * Refactors landlock_create_ruleset() - splits ruleset and >>>>>> masks checks. >>>>>> * Refactors landlock_create_ruleset() and landlock mask >>>>>> setters/getters to support two rule types. >>>>>> * Refactors landlock_add_rule syscall add_rule_path_beneath >>>>>> function by factoring out get_ruleset_from_fd() and >>>>>> landlock_put_ruleset(). >>>>>> >>>>>> Changes since v3: >>>>>> * Splits commit. >>>>>> * Adds network rule support for internal landlock functions. >>>>>> * Adds set_mask and get_mask for network. >>>>>> * Adds rb_root root_net_port. >>>>>> >>>>>> --- >>>>>> include/uapi/linux/landlock.h | 49 +++++ >>>>>> security/landlock/Kconfig | 1 + >>>>>> security/landlock/Makefile | 2 + >>>>>> security/landlock/limits.h | 6 +- >>>>>> security/landlock/net.c | 198 +++++++++++++++++++ >>>>>> security/landlock/net.h | 26 +++ >>>>>> security/landlock/ruleset.c | 52 ++++- >>>>>> security/landlock/ruleset.h | 63 +++++- >>>>>> security/landlock/setup.c | 2 + >>>>>> security/landlock/syscalls.c | 72 ++++++- >>>>>> tools/testing/selftests/landlock/base_test.c | 2 +- >>>>>> 11 files changed, 450 insertions(+), 23 deletions(-) >>>>>> create mode 100644 security/landlock/net.c >>>>>> create mode 100644 security/landlock/net.h >>>>> >>>>> [...] >>>>> >>>>>> diff --git a/security/landlock/net.c b/security/landlock/net.c >>>>> >>>>> [...] >>>>> >>>>>> +static int check_addrlen(const struct sockaddr *const address, int addrlen) >>>>> >>>>> const int addrlen >>>> >>>> Got it. >>>>> >>>>>> +{ >>>>>> + if (addrlen < offsetofend(struct sockaddr, sa_family)) >>>>>> + return -EINVAL; >>>>>> + switch (address->sa_family) { >>>>>> + case AF_UNSPEC: >>>>>> + case AF_INET: >>>>>> + if (addrlen < sizeof(struct sockaddr_in)) >>>>>> + return -EINVAL; >>>>>> + return 0; >>>>>> +#if IS_ENABLED(CONFIG_IPV6) >>>>>> + case AF_INET6: >>>>>> + if (addrlen < SIN6_LEN_RFC2133) >>>>>> + return -EINVAL; >>>>>> + return 0; >>>>>> +#endif >>>>>> + } >>>>>> + WARN_ON_ONCE(1); >>>>>> + return 0; >>>>>> +} >>>>>> + >>>>>> +static u16 get_port(const struct sockaddr *const address) >>>>>> +{ >>>>>> + /* Gets port value in host byte order. */ >>>>>> + switch (address->sa_family) { >>>>>> + case AF_UNSPEC: >>>>>> + case AF_INET: { >>>>>> + const struct sockaddr_in *const sockaddr = >>>>>> + (struct sockaddr_in *)address; >>>>>> + return ntohs(sockaddr->sin_port); >>>>> >>>>> Storing ports in big endian (in rulesets) would avoid converting them >>>>> every time the kernel checks a socket port. The above comment should >>>>> then be updated too. >>>> >>>> I thought we came to a conclusion to stick to host endianess and >>>> let kernel do the checks under the hood: >>>> https://lore.kernel.org/linux-security-module/278ab07f-7583-a4e0-3d37-1bacd091531d@digikod.net/ >>>> >>>> Did I misunderstand something? >>> >>> We indeed stick to the host endianess for the UAPI/syscalls, but >>> internally the kernel has to do the conversion with as it is currently >>> done by calling ntohs(). To avoid calling ntohs() every time get_port() >>> is called, we can instead only call htons() when creating rules (i.e. >>> one-time htons call instead of multiple ntohs calls). >>> >> Do you mean we need to covert port in landlock_append_net_rule(): >> >> ... >> >> int err; >> const struct landlock_id id = { >> .key.data = ntohs(port), >> .type = LANDLOCK_KEY_NET_PORT, >> }; >> BUILD_BUG_ON(sizeof(port) > sizeof(id.key.data)); >> ... >> ???? > > landlock_append_net_rule() takes a u16 (host endianess, which is the > case with this patch series) and should store a big endian 16-bit > integer. See my patch: > > const struct landlock_id id = { > - .key.data = port, > + .key.data = (__force uintptr_t)htons(port), > .type = LANDLOCK_KEY_NET_PORT, > }; > Thanks. Already took a look. > > >>> >>>> Do you mean we need to do port converting __be16 -> u16 in >>>> check_socket_access()??? >>> >>> Removing the ntohs() call from get_port() enables to return __be16 >>> instead of u16, and check_socket_access() will then need to use the same >>> type. >> >> Ok. I got it. Thanks. >>> >>> >>>>> >>>>> >>>>>> + } >>>>>> +#if IS_ENABLED(CONFIG_IPV6) >>>>>> + case AF_INET6: { >>>>>> + const struct sockaddr_in6 *const sockaddr_ip6 = >>>>>> + (struct sockaddr_in6 *)address; >>>>>> + return ntohs(sockaddr_ip6->sin6_port); >>>>>> + } >>>>>> +#endif >>>>>> + } >>>>>> + WARN_ON_ONCE(1); >>>>>> + return 0; >>>>>> +} >>>>>> + >>>>>> +static int check_socket_access(struct socket *sock, struct sockaddr *address, int addrlen, u16 port, >>>>>> + access_mask_t access_request) >>>>>> +{ >>>>>> + int ret; >>>>>> + bool allowed = false; >>>>>> + layer_mask_t layer_masks[LANDLOCK_NUM_ACCESS_NET] = {}; >>>>>> + const struct landlock_rule *rule; >>>>>> + access_mask_t handled_access; >>>>>> + const struct landlock_id id = { >>>>>> + .key.data = port, >>>>>> + .type = LANDLOCK_KEY_NET_PORT, >>>>>> + }; >>>>>> + const struct landlock_ruleset *const domain = get_current_net_domain(); >>>>>> + >>>>>> + if (WARN_ON_ONCE(!domain)) >>>>>> + return 0; >>>>>> + if (WARN_ON_ONCE(domain->num_layers < 1)) >>>>>> + return -EACCES; >>>>>> + /* Check if it's a TCP socket. */ >>>>>> + if (sock->type != SOCK_STREAM) >>>>>> + return 0; >>>>>> + >>>>>> + ret = check_addrlen(address, addrlen); >>>>>> + if (ret) >>>>>> + return ret; >>>>>> + >>>>>> + switch (address->sa_family) { >>>>>> + case AF_UNSPEC: >>>>>> + /* >>>>>> + * Connecting to an address with AF_UNSPEC dissolves the TCP >>>>>> + * association, which have the same effect as closing the >>>>>> + * connection while retaining the socket object (i.e., the file >>>>>> + * descriptor). As for dropping privileges, closing >>>>>> + * connections is always allowed. >>>>>> + */ >>>>>> + if (access_request == LANDLOCK_ACCESS_NET_CONNECT_TCP) >>>>>> + return 0; >>>>>> + >>>>>> + /* >>>>>> + * For compatibility reason, accept AF_UNSPEC for bind >>>>>> + * accesses (mapped to AF_INET) only if the address is >>>>>> + * INADDR_ANY (cf. __inet_bind). Checking the address is >>>>>> + * required to not wrongfully return -EACCES instead of >>>>>> + * -EAFNOSUPPORT. >>>>>> + */ >>>>>> + if (access_request == LANDLOCK_ACCESS_NET_BIND_TCP) { >>>>>> + const struct sockaddr_in *const sockaddr = >>>>>> + (struct sockaddr_in *)address; >>>>>> + >>>>>> + if (sockaddr->sin_addr.s_addr != htonl(INADDR_ANY)) >>>>>> + return -EAFNOSUPPORT; >>>>>> + } >>>>>> + >>>>>> + fallthrough; >>>>>> + case AF_INET: >>>>>> +#if IS_ENABLED(CONFIG_IPV6) >>>>>> + case AF_INET6: >>>>>> +#endif >>>>>> + rule = landlock_find_rule(domain, id); >>>>>> + handled_access = landlock_init_layer_masks( >>>>>> + domain, access_request, &layer_masks, >>>>>> + LANDLOCK_KEY_NET_PORT); >>>>>> + allowed = landlock_unmask_layers(rule, handled_access, >>>>>> + &layer_masks, >>>>>> + ARRAY_SIZE(layer_masks)); >>>>>> + } >>>>>> + return allowed ? 0 : -EACCES; >>>>>> +} >>>>>> + >>>>>> +static int hook_socket_bind(struct socket *sock, struct sockaddr *address, >>>>>> + int addrlen) >>>>>> +{ >>> + return check_socket_access(sock, address, addrlen, get_port(address), >>>>>> + LANDLOCK_ACCESS_NET_BIND_TCP); >>> >>> get_port() is called before check_addrlen(), which is an issue. >>> >>> You'll find attached a patch for these fixes, please squash it in this >>> one for the next version. >>> >>> I'll send other reviews by the end of the week. >>> >>> >>>>>> +} >>>>>> + >>>>>> +static int hook_socket_connect(struct socket *sock, struct sockaddr *address, >>>>>> + int addrlen) >>>>>> +{ >>>>>> + return check_socket_access(sock, address, addrlen, get_port(address), >>>>>> + LANDLOCK_ACCESS_NET_CONNECT_TCP); >>>>>> +} >>>>> >>>>> [...] >>>>> . > .
On 05/04/2023 21:19, Konstantin Meskhidze (A) wrote: > > > 4/4/2023 8:02 PM, Mickaël Salaün пишет: >> >> On 04/04/2023 18:42, Mickaël Salaün wrote: >>> >>> On 04/04/2023 11:31, Konstantin Meskhidze (A) wrote: >>>> >>>> >>>> 3/31/2023 8:24 PM, Mickaël Salaün пишет: >>>>> >>>>> On 23/03/2023 09:52, Konstantin Meskhidze wrote: >>>>>> This commit adds network rules support in the ruleset management >>>>>> helpers and the landlock_create_ruleset syscall. >>>>>> Refactor user space API to support network actions. Add new network >>>>>> access flags, network rule and network attributes. Increment Landlock >>>>>> ABI version. Expand access_masks_t to u32 to be sure network access >>>>>> rights can be stored. Implement socket_bind() and socket_connect() >>>>>> LSM hooks, which enable to restrict TCP socket binding and connection >>>>>> to specific ports. >>>>>> >>>>>> Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@huawei.com> >>>>>> --- >>>>>> >>>>>> Changes since v9: >>>>>> * Changes UAPI port field to __u64. >>>>>> * Moves shared code into check_socket_access(). >>>>>> * Adds get_raw_handled_net_accesses() and >>>>>> get_current_net_domain() helpers. >>>>>> * Minor fixes. >>>>>> >>>>>> Changes since v8: >>>>>> * Squashes commits. >>>>>> * Refactors commit message. >>>>>> * Changes UAPI port field to __be16. >>>>>> * Changes logic of bind/connect hooks with AF_UNSPEC families. >>>>>> * Adds address length checking. >>>>>> * Minor fixes. >>>>>> >>>>>> Changes since v7: >>>>>> * Squashes commits. >>>>>> * Increments ABI version to 4. >>>>>> * Refactors commit message. >>>>>> * Minor fixes. >>>>>> >>>>>> Changes since v6: >>>>>> * Renames landlock_set_net_access_mask() to landlock_add_net_access_mask() >>>>>> because it OR values. >>>>>> * Makes landlock_add_net_access_mask() more resilient incorrect values. >>>>>> * Refactors landlock_get_net_access_mask(). >>>>>> * Renames LANDLOCK_MASK_SHIFT_NET to LANDLOCK_SHIFT_ACCESS_NET and use >>>>>> LANDLOCK_NUM_ACCESS_FS as value. >>>>>> * Updates access_masks_t to u32 to support network access actions. >>>>>> * Refactors landlock internal functions to support network actions with >>>>>> landlock_key/key_type/id types. >>>>>> >>>>>> Changes since v5: >>>>>> * Gets rid of partial revert from landlock_add_rule >>>>>> syscall. >>>>>> * Formats code with clang-format-14. >>>>>> >>>>>> Changes since v4: >>>>>> * Refactors landlock_create_ruleset() - splits ruleset and >>>>>> masks checks. >>>>>> * Refactors landlock_create_ruleset() and landlock mask >>>>>> setters/getters to support two rule types. >>>>>> * Refactors landlock_add_rule syscall add_rule_path_beneath >>>>>> function by factoring out get_ruleset_from_fd() and >>>>>> landlock_put_ruleset(). >>>>>> >>>>>> Changes since v3: >>>>>> * Splits commit. >>>>>> * Adds network rule support for internal landlock functions. >>>>>> * Adds set_mask and get_mask for network. >>>>>> * Adds rb_root root_net_port. >>>>>> >>>>>> --- >>>>>> include/uapi/linux/landlock.h | 49 +++++ >>>>>> security/landlock/Kconfig | 1 + >>>>>> security/landlock/Makefile | 2 + >>>>>> security/landlock/limits.h | 6 +- >>>>>> security/landlock/net.c | 198 +++++++++++++++++++ >>>>>> security/landlock/net.h | 26 +++ >>>>>> security/landlock/ruleset.c | 52 ++++- >>>>>> security/landlock/ruleset.h | 63 +++++- >>>>>> security/landlock/setup.c | 2 + >>>>>> security/landlock/syscalls.c | 72 ++++++- >>>>>> tools/testing/selftests/landlock/base_test.c | 2 +- >>>>>> 11 files changed, 450 insertions(+), 23 deletions(-) >>>>>> create mode 100644 security/landlock/net.c >>>>>> create mode 100644 security/landlock/net.h >>>>> >>>>> [...] >>>>> >>>>>> diff --git a/security/landlock/net.c b/security/landlock/net.c >>>>> >>>>> [...] >> >> >>>>>> +static int check_socket_access(struct socket *sock, struct sockaddr *address, int addrlen, u16 port, >>>>>> + access_mask_t access_request) >>>>>> +{ >>>>>> + int ret; >>>>>> + bool allowed = false; >>>>>> + layer_mask_t layer_masks[LANDLOCK_NUM_ACCESS_NET] = {}; >>>>>> + const struct landlock_rule *rule; >>>>>> + access_mask_t handled_access; >>>>>> + const struct landlock_id id = { >>>>>> + .key.data = port, >>>>>> + .type = LANDLOCK_KEY_NET_PORT, >>>>>> + }; >>>>>> + const struct landlock_ruleset *const domain = get_current_net_domain(); >>>>>> + >>>>>> + if (WARN_ON_ONCE(!domain)) >>>>>> + return 0; >>>>>> + if (WARN_ON_ONCE(domain->num_layers < 1)) >>>>>> + return -EACCES; >>>>>> + /* Check if it's a TCP socket. */ >>>>>> + if (sock->type != SOCK_STREAM) >>>>>> + return 0; >>>>>> + >>>>>> + ret = check_addrlen(address, addrlen); >>>>>> + if (ret) >>>>>> + return ret; >>>>>> + >>>>>> + switch (address->sa_family) { >>>>>> + case AF_UNSPEC: >>>>>> + /* >>>>>> + * Connecting to an address with AF_UNSPEC dissolves the TCP >>>>>> + * association, which have the same effect as closing the >>>>>> + * connection while retaining the socket object (i.e., the file >>>>>> + * descriptor). As for dropping privileges, closing >>>>>> + * connections is always allowed. >>>>>> + */ >>>>>> + if (access_request == LANDLOCK_ACCESS_NET_CONNECT_TCP) >>>>>> + return 0; >>>>>> + >>>>>> + /* >>>>>> + * For compatibility reason, accept AF_UNSPEC for bind >>>>>> + * accesses (mapped to AF_INET) only if the address is >>>>>> + * INADDR_ANY (cf. __inet_bind). Checking the address is >>>>>> + * required to not wrongfully return -EACCES instead of >>>>>> + * -EAFNOSUPPORT. >>>>>> + */ >>>>>> + if (access_request == LANDLOCK_ACCESS_NET_BIND_TCP) { >>>>>> + const struct sockaddr_in *const sockaddr = >>>>>> + (struct sockaddr_in *)address; >>>>>> + >>>>>> + if (sockaddr->sin_addr.s_addr != htonl(INADDR_ANY)) >>>>>> + return -EAFNOSUPPORT; >>>>>> + } >>>>>> + >>>>>> + fallthrough; >>>>>> + case AF_INET: >>>>>> +#if IS_ENABLED(CONFIG_IPV6) >>>>>> + case AF_INET6: >>>>>> +#endif >> >> Some more fixes: >> >> You can move the port/id.key.data block from my patch here, where it is >> actually used. >> > Ok. Thank you. I will apply it. >> >>>>>> + rule = landlock_find_rule(domain, id); >>>>>> + handled_access = landlock_init_layer_masks( >>>>>> + domain, access_request, &layer_masks, >>>>>> + LANDLOCK_KEY_NET_PORT); >>>>>> + allowed = landlock_unmask_layers(rule, handled_access, >>>>>> + &layer_masks, >>>>>> + ARRAY_SIZE(layer_masks)); >> >> The `return allowed ? 0 : -EACCES;` should be here. >> >>>>>> + } >>>>>> + return allowed ? 0 : -EACCES; >> >> We should have `return 0;` here. >> > Got it. Thanks > >> We need a test for an sa_family different than AF_UNSPEC, AF_INET, and >> AF_INET6 to make sure everything else is allowed (e.g. AF_UNIX with >> SOCK_STREAM and another test with SOCK_DGRAM). Please make sure this new >> test will not pass with SOCK_STREAM and the current patch series, but of >> course it should pass with the next one. > > Do you mean AF_UNIX with SOCK_STREAM will not be passed as well as > AF_UNIX with SOCK_DGRAM? AF_UNIX with SOCK_STREAM would be denied with this patch series, which is a bug. AF_UNIX with SOCK_DGRAM should always be allowed with this patch series, which is correct. AF_UNIX with SOCK_STREAM or SOCK_DGRAM should always be allowed, and the next patch series should come with a new test to check this two kind of sockets.
4/6/2023 1:31 PM, Mickaël Salaün пишет: > > On 05/04/2023 21:19, Konstantin Meskhidze (A) wrote: >> >> >> 4/4/2023 8:02 PM, Mickaël Salaün пишет: >>> >>> On 04/04/2023 18:42, Mickaël Salaün wrote: >>>> >>>> On 04/04/2023 11:31, Konstantin Meskhidze (A) wrote: >>>>> >>>>> >>>>> 3/31/2023 8:24 PM, Mickaël Salaün пишет: >>>>>> >>>>>> On 23/03/2023 09:52, Konstantin Meskhidze wrote: >>>>>>> This commit adds network rules support in the ruleset management >>>>>>> helpers and the landlock_create_ruleset syscall. >>>>>>> Refactor user space API to support network actions. Add new network >>>>>>> access flags, network rule and network attributes. Increment Landlock >>>>>>> ABI version. Expand access_masks_t to u32 to be sure network access >>>>>>> rights can be stored. Implement socket_bind() and socket_connect() >>>>>>> LSM hooks, which enable to restrict TCP socket binding and connection >>>>>>> to specific ports. >>>>>>> >>>>>>> Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@huawei.com> >>>>>>> --- >>>>>>> >>>>>>> Changes since v9: >>>>>>> * Changes UAPI port field to __u64. >>>>>>> * Moves shared code into check_socket_access(). >>>>>>> * Adds get_raw_handled_net_accesses() and >>>>>>> get_current_net_domain() helpers. >>>>>>> * Minor fixes. >>>>>>> >>>>>>> Changes since v8: >>>>>>> * Squashes commits. >>>>>>> * Refactors commit message. >>>>>>> * Changes UAPI port field to __be16. >>>>>>> * Changes logic of bind/connect hooks with AF_UNSPEC families. >>>>>>> * Adds address length checking. >>>>>>> * Minor fixes. >>>>>>> >>>>>>> Changes since v7: >>>>>>> * Squashes commits. >>>>>>> * Increments ABI version to 4. >>>>>>> * Refactors commit message. >>>>>>> * Minor fixes. >>>>>>> >>>>>>> Changes since v6: >>>>>>> * Renames landlock_set_net_access_mask() to landlock_add_net_access_mask() >>>>>>> because it OR values. >>>>>>> * Makes landlock_add_net_access_mask() more resilient incorrect values. >>>>>>> * Refactors landlock_get_net_access_mask(). >>>>>>> * Renames LANDLOCK_MASK_SHIFT_NET to LANDLOCK_SHIFT_ACCESS_NET and use >>>>>>> LANDLOCK_NUM_ACCESS_FS as value. >>>>>>> * Updates access_masks_t to u32 to support network access actions. >>>>>>> * Refactors landlock internal functions to support network actions with >>>>>>> landlock_key/key_type/id types. >>>>>>> >>>>>>> Changes since v5: >>>>>>> * Gets rid of partial revert from landlock_add_rule >>>>>>> syscall. >>>>>>> * Formats code with clang-format-14. >>>>>>> >>>>>>> Changes since v4: >>>>>>> * Refactors landlock_create_ruleset() - splits ruleset and >>>>>>> masks checks. >>>>>>> * Refactors landlock_create_ruleset() and landlock mask >>>>>>> setters/getters to support two rule types. >>>>>>> * Refactors landlock_add_rule syscall add_rule_path_beneath >>>>>>> function by factoring out get_ruleset_from_fd() and >>>>>>> landlock_put_ruleset(). >>>>>>> >>>>>>> Changes since v3: >>>>>>> * Splits commit. >>>>>>> * Adds network rule support for internal landlock functions. >>>>>>> * Adds set_mask and get_mask for network. >>>>>>> * Adds rb_root root_net_port. >>>>>>> >>>>>>> --- >>>>>>> include/uapi/linux/landlock.h | 49 +++++ >>>>>>> security/landlock/Kconfig | 1 + >>>>>>> security/landlock/Makefile | 2 + >>>>>>> security/landlock/limits.h | 6 +- >>>>>>> security/landlock/net.c | 198 +++++++++++++++++++ >>>>>>> security/landlock/net.h | 26 +++ >>>>>>> security/landlock/ruleset.c | 52 ++++- >>>>>>> security/landlock/ruleset.h | 63 +++++- >>>>>>> security/landlock/setup.c | 2 + >>>>>>> security/landlock/syscalls.c | 72 ++++++- >>>>>>> tools/testing/selftests/landlock/base_test.c | 2 +- >>>>>>> 11 files changed, 450 insertions(+), 23 deletions(-) >>>>>>> create mode 100644 security/landlock/net.c >>>>>>> create mode 100644 security/landlock/net.h >>>>>> >>>>>> [...] >>>>>> >>>>>>> diff --git a/security/landlock/net.c b/security/landlock/net.c >>>>>> >>>>>> [...] >>> >>> >>>>>>> +static int check_socket_access(struct socket *sock, struct sockaddr *address, int addrlen, u16 port, >>>>>>> + access_mask_t access_request) >>>>>>> +{ >>>>>>> + int ret; >>>>>>> + bool allowed = false; >>>>>>> + layer_mask_t layer_masks[LANDLOCK_NUM_ACCESS_NET] = {}; >>>>>>> + const struct landlock_rule *rule; >>>>>>> + access_mask_t handled_access; >>>>>>> + const struct landlock_id id = { >>>>>>> + .key.data = port, >>>>>>> + .type = LANDLOCK_KEY_NET_PORT, >>>>>>> + }; >>>>>>> + const struct landlock_ruleset *const domain = get_current_net_domain(); >>>>>>> + >>>>>>> + if (WARN_ON_ONCE(!domain)) >>>>>>> + return 0; >>>>>>> + if (WARN_ON_ONCE(domain->num_layers < 1)) >>>>>>> + return -EACCES; >>>>>>> + /* Check if it's a TCP socket. */ >>>>>>> + if (sock->type != SOCK_STREAM) >>>>>>> + return 0; >>>>>>> + >>>>>>> + ret = check_addrlen(address, addrlen); >>>>>>> + if (ret) >>>>>>> + return ret; >>>>>>> + >>>>>>> + switch (address->sa_family) { >>>>>>> + case AF_UNSPEC: >>>>>>> + /* >>>>>>> + * Connecting to an address with AF_UNSPEC dissolves the TCP >>>>>>> + * association, which have the same effect as closing the >>>>>>> + * connection while retaining the socket object (i.e., the file >>>>>>> + * descriptor). As for dropping privileges, closing >>>>>>> + * connections is always allowed. >>>>>>> + */ >>>>>>> + if (access_request == LANDLOCK_ACCESS_NET_CONNECT_TCP) >>>>>>> + return 0; >>>>>>> + >>>>>>> + /* >>>>>>> + * For compatibility reason, accept AF_UNSPEC for bind >>>>>>> + * accesses (mapped to AF_INET) only if the address is >>>>>>> + * INADDR_ANY (cf. __inet_bind). Checking the address is >>>>>>> + * required to not wrongfully return -EACCES instead of >>>>>>> + * -EAFNOSUPPORT. >>>>>>> + */ >>>>>>> + if (access_request == LANDLOCK_ACCESS_NET_BIND_TCP) { >>>>>>> + const struct sockaddr_in *const sockaddr = >>>>>>> + (struct sockaddr_in *)address; >>>>>>> + >>>>>>> + if (sockaddr->sin_addr.s_addr != htonl(INADDR_ANY)) >>>>>>> + return -EAFNOSUPPORT; >>>>>>> + } >>>>>>> + >>>>>>> + fallthrough; >>>>>>> + case AF_INET: >>>>>>> +#if IS_ENABLED(CONFIG_IPV6) >>>>>>> + case AF_INET6: >>>>>>> +#endif >>> >>> Some more fixes: >>> >>> You can move the port/id.key.data block from my patch here, where it is >>> actually used. >>> >> Ok. Thank you. I will apply it. >>> >>>>>>> + rule = landlock_find_rule(domain, id); >>>>>>> + handled_access = landlock_init_layer_masks( >>>>>>> + domain, access_request, &layer_masks, >>>>>>> + LANDLOCK_KEY_NET_PORT); >>>>>>> + allowed = landlock_unmask_layers(rule, handled_access, >>>>>>> + &layer_masks, >>>>>>> + ARRAY_SIZE(layer_masks)); >>> >>> The `return allowed ? 0 : -EACCES;` should be here. >>> >>>>>>> + } >>>>>>> + return allowed ? 0 : -EACCES; >>> >>> We should have `return 0;` here. >>> >> Got it. Thanks >> >>> We need a test for an sa_family different than AF_UNSPEC, AF_INET, and >>> AF_INET6 to make sure everything else is allowed (e.g. AF_UNIX with >>> SOCK_STREAM and another test with SOCK_DGRAM). Please make sure this new >>> test will not pass with SOCK_STREAM and the current patch series, but of >>> course it should pass with the next one. >> >> Do you mean AF_UNIX with SOCK_STREAM will not be passed as well as >> AF_UNIX with SOCK_DGRAM? > > AF_UNIX with SOCK_STREAM would be denied with this patch series, which > is a bug. AF_UNIX with SOCK_DGRAM should always be allowed with this > patch series, which is correct. > > AF_UNIX with SOCK_STREAM or SOCK_DGRAM should always be allowed, and the > next patch series should come with a new test to check this two kind of > sockets. Got it. Thanks. > .
On 23/03/2023 09:52, Konstantin Meskhidze wrote: > This commit adds network rules support in the ruleset management > helpers and the landlock_create_ruleset syscall. > Refactor user space API to support network actions. Add new network > access flags, network rule and network attributes. Increment Landlock > ABI version. Expand access_masks_t to u32 to be sure network access > rights can be stored. Implement socket_bind() and socket_connect() > LSM hooks, which enable to restrict TCP socket binding and connection "which enables to" > to specific ports. > > Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@huawei.com> > --- > > Changes since v9: > * Changes UAPI port field to __u64. > * Moves shared code into check_socket_access(). > * Adds get_raw_handled_net_accesses() and > get_current_net_domain() helpers. > * Minor fixes. > > Changes since v8: > * Squashes commits. > * Refactors commit message. > * Changes UAPI port field to __be16. > * Changes logic of bind/connect hooks with AF_UNSPEC families. > * Adds address length checking. > * Minor fixes. > > Changes since v7: > * Squashes commits. > * Increments ABI version to 4. > * Refactors commit message. > * Minor fixes. > > Changes since v6: > * Renames landlock_set_net_access_mask() to landlock_add_net_access_mask() > because it OR values. > * Makes landlock_add_net_access_mask() more resilient incorrect values. > * Refactors landlock_get_net_access_mask(). > * Renames LANDLOCK_MASK_SHIFT_NET to LANDLOCK_SHIFT_ACCESS_NET and use > LANDLOCK_NUM_ACCESS_FS as value. > * Updates access_masks_t to u32 to support network access actions. > * Refactors landlock internal functions to support network actions with > landlock_key/key_type/id types. > > Changes since v5: > * Gets rid of partial revert from landlock_add_rule > syscall. > * Formats code with clang-format-14. > > Changes since v4: > * Refactors landlock_create_ruleset() - splits ruleset and > masks checks. > * Refactors landlock_create_ruleset() and landlock mask > setters/getters to support two rule types. > * Refactors landlock_add_rule syscall add_rule_path_beneath > function by factoring out get_ruleset_from_fd() and > landlock_put_ruleset(). > > Changes since v3: > * Splits commit. > * Adds network rule support for internal landlock functions. > * Adds set_mask and get_mask for network. > * Adds rb_root root_net_port. > > --- > include/uapi/linux/landlock.h | 49 +++++ > security/landlock/Kconfig | 1 + > security/landlock/Makefile | 2 + > security/landlock/limits.h | 6 +- > security/landlock/net.c | 198 +++++++++++++++++++ > security/landlock/net.h | 26 +++ > security/landlock/ruleset.c | 52 ++++- > security/landlock/ruleset.h | 63 +++++- > security/landlock/setup.c | 2 + > security/landlock/syscalls.c | 72 ++++++- > tools/testing/selftests/landlock/base_test.c | 2 +- > 11 files changed, 450 insertions(+), 23 deletions(-) > create mode 100644 security/landlock/net.c > create mode 100644 security/landlock/net.h > > diff --git a/include/uapi/linux/landlock.h b/include/uapi/linux/landlock.h > index 81d09ef9aa50..09b70fb6a9a6 100644 > --- a/include/uapi/linux/landlock.h > +++ b/include/uapi/linux/landlock.h > @@ -31,6 +31,13 @@ struct landlock_ruleset_attr { > * this access right. > */ > __u64 handled_access_fs; > + > + /** > + * @handled_access_net: Bitmask of actions (cf. `Network flags`_) > + * that is handled by this ruleset and should then be forbidden if no > + * rule explicitly allow them. > + */ > + __u64 handled_access_net; > }; > > /* > @@ -54,6 +61,11 @@ enum landlock_rule_type { > * landlock_path_beneath_attr . > */ > LANDLOCK_RULE_PATH_BENEATH = 1, > + /** > + * @LANDLOCK_RULE_NET_SERVICE: Type of a &struct > + * landlock_net_service_attr . > + */ > + LANDLOCK_RULE_NET_SERVICE = 2, > }; > > /** > @@ -79,6 +91,24 @@ struct landlock_path_beneath_attr { > */ > } __attribute__((packed)); > > +/** > + * struct landlock_net_service_attr - TCP subnet definition > + * > + * Argument of sys_landlock_add_rule(). > + */ > +struct landlock_net_service_attr { > + /** > + * @allowed_access: Bitmask of allowed access network for services > + * (cf. `Network flags`_). > + */ > + __u64 allowed_access; > + /** > + * @port: Network port. > + */ > + __u64 port; > + > +} __attribute__((packed)); You can remove the empty line and the packed attribute. > + > /** > * DOC: fs_access > * > @@ -189,4 +219,23 @@ struct landlock_path_beneath_attr { > #define LANDLOCK_ACCESS_FS_TRUNCATE (1ULL << 14) > /* clang-format on */ > > +/** > + * DOC: net_access > + * > + * Network flags > + * ~~~~~~~~~~~~~~~~ > + * > + * These flags enable to restrict a sandboxed process to a set of network > + * actions. > + * > + * TCP sockets with allowed actions: > + * > + * - %LANDLOCK_ACCESS_NET_BIND_TCP: Bind a TCP socket to a local port. > + * - %LANDLOCK_ACCESS_NET_CONNECT_TCP: Connect an active TCP socket to > + * a remote port. > + */ > +/* clang-format off */ > +#define LANDLOCK_ACCESS_NET_BIND_TCP (1ULL << 0) > +#define LANDLOCK_ACCESS_NET_CONNECT_TCP (1ULL << 1) > +/* clang-format on */ > #endif /* _UAPI_LINUX_LANDLOCK_H */ > diff --git a/security/landlock/Kconfig b/security/landlock/Kconfig > index 8e33c4e8ffb8..10c099097533 100644 > --- a/security/landlock/Kconfig > +++ b/security/landlock/Kconfig > @@ -3,6 +3,7 @@ > config SECURITY_LANDLOCK > bool "Landlock support" > depends on SECURITY && !ARCH_EPHEMERAL_INODES > + select SECURITY_NETWORK > select SECURITY_PATH > help > Landlock is a sandboxing mechanism that enables processes to restrict > diff --git a/security/landlock/Makefile b/security/landlock/Makefile > index 7bbd2f413b3e..53d3c92ae22e 100644 > --- a/security/landlock/Makefile > +++ b/security/landlock/Makefile > @@ -2,3 +2,5 @@ obj-$(CONFIG_SECURITY_LANDLOCK) := landlock.o > > landlock-y := setup.o syscalls.o object.o ruleset.o \ > cred.o ptrace.o fs.o > + > +landlock-$(CONFIG_INET) += net.o > \ No newline at end of file > diff --git a/security/landlock/limits.h b/security/landlock/limits.h > index bafb3b8dc677..8a1a6463c64e 100644 > --- a/security/landlock/limits.h > +++ b/security/landlock/limits.h > @@ -23,6 +23,10 @@ > #define LANDLOCK_NUM_ACCESS_FS __const_hweight64(LANDLOCK_MASK_ACCESS_FS) > #define LANDLOCK_SHIFT_ACCESS_FS 0 > > -/* clang-format on */ > +#define LANDLOCK_LAST_ACCESS_NET LANDLOCK_ACCESS_NET_CONNECT_TCP > +#define LANDLOCK_MASK_ACCESS_NET ((LANDLOCK_LAST_ACCESS_NET << 1) - 1) > +#define LANDLOCK_NUM_ACCESS_NET __const_hweight64(LANDLOCK_MASK_ACCESS_NET) > +#define LANDLOCK_SHIFT_ACCESS_NET LANDLOCK_NUM_ACCESS_FS > > +/* clang-format on */ > #endif /* _SECURITY_LANDLOCK_LIMITS_H */ > diff --git a/security/landlock/net.c b/security/landlock/net.c > new file mode 100644 > index 000000000000..e19c339906e7 > --- /dev/null > +++ b/security/landlock/net.c > @@ -0,0 +1,198 @@ > +// SPDX-License-Identifier: GPL-2.0-only > +/* > + * Landlock LSM - Network management and hooks > + * > + * Copyright © 2022 Huawei Tech. Co., Ltd. > + * Copyright © 2022 Microsoft Corporation > + */ > + > +#include <linux/in.h> > +#include <linux/net.h> > +#include <linux/socket.h> > +#include <net/ipv6.h> > + > +#include "common.h" > +#include "cred.h" > +#include "limits.h" > +#include "net.h" > +#include "ruleset.h" > + > +int landlock_append_net_rule(struct landlock_ruleset *const ruleset, > + const u16 port, access_mask_t access_rights) > +{ > + int err; > + const struct landlock_id id = { > + .key.data = port, > + .type = LANDLOCK_KEY_NET_PORT, > + }; > + BUILD_BUG_ON(sizeof(port) > sizeof(id.key.data)); > + > + /* Transforms relative access rights to absolute ones. */ > + access_rights |= LANDLOCK_MASK_ACCESS_NET & > + ~landlock_get_net_access_mask(ruleset, 0); > + > + mutex_lock(&ruleset->lock); > + err = landlock_insert_rule(ruleset, id, access_rights); > + mutex_unlock(&ruleset->lock); > + > + return err; > +} > + > +static access_mask_t > +get_raw_handled_net_accesses(const struct landlock_ruleset *const domain) > +{ > + access_mask_t access_dom = 0; > + size_t layer_level; > + > + for (layer_level = 0; layer_level < domain->num_layers; layer_level++) > + access_dom |= landlock_get_net_access_mask(domain, layer_level); > + return access_dom; > +} > + > +static const struct landlock_ruleset *get_current_net_domain(void) > +{ > + const struct landlock_ruleset *const dom = > + landlock_get_current_domain(); > + > + if (!dom || !get_raw_handled_net_accesses(dom)) > + return NULL; > + > + return dom; > +} > + > +static int check_addrlen(const struct sockaddr *const address, int addrlen) > +{ > + if (addrlen < offsetofend(struct sockaddr, sa_family)) > + return -EINVAL; > + switch (address->sa_family) { > + case AF_UNSPEC: > + case AF_INET: > + if (addrlen < sizeof(struct sockaddr_in)) > + return -EINVAL; > + return 0; > +#if IS_ENABLED(CONFIG_IPV6) > + case AF_INET6: > + if (addrlen < SIN6_LEN_RFC2133) > + return -EINVAL; > + return 0; > +#endif > + } > + WARN_ON_ONCE(1); > + return 0; With this code, using any non-TCP socket would print a warning. All these switch/case make difficult to check consistency across check_addrlen() and get_port() helpers, they should be inlined into check_socket_access(), with only one switch statement, but we need to be careful about the return error orders: first EINVAL and after EAFNOSUPPORT. Inlining all this also enables to get rid of impossible cases (that lead to these WARN_ON_ONCE calls). > +} > + > +static u16 get_port(const struct sockaddr *const address) > +{ > + /* Gets port value in host byte order. */ > + switch (address->sa_family) { > + case AF_UNSPEC: > + case AF_INET: { > + const struct sockaddr_in *const sockaddr = > + (struct sockaddr_in *)address; > + return ntohs(sockaddr->sin_port); > + } > +#if IS_ENABLED(CONFIG_IPV6) > + case AF_INET6: { > + const struct sockaddr_in6 *const sockaddr_ip6 = > + (struct sockaddr_in6 *)address; > + return ntohs(sockaddr_ip6->sin6_port); > + } > +#endif > + } > + WARN_ON_ONCE(1); > + return 0; > +} > + > +static int check_socket_access(struct socket *sock, struct sockaddr *address, int addrlen, u16 port, > + access_mask_t access_request) > +{ > + int ret; > + bool allowed = false; > + layer_mask_t layer_masks[LANDLOCK_NUM_ACCESS_NET] = {}; > + const struct landlock_rule *rule; > + access_mask_t handled_access; > + const struct landlock_id id = { > + .key.data = port, > + .type = LANDLOCK_KEY_NET_PORT, > + }; > + const struct landlock_ruleset *const domain = get_current_net_domain(); > + > + if (WARN_ON_ONCE(!domain)) > + return 0; > + if (WARN_ON_ONCE(domain->num_layers < 1)) > + return -EACCES; > + /* Check if it's a TCP socket. */ > + if (sock->type != SOCK_STREAM) > + return 0; > + > + ret = check_addrlen(address, addrlen); > + if (ret) > + return ret; As explained above, this should be replaced with: if (addrlen < offsetofend(struct sockaddr, sa_family)) return -EINVAL; > + > + switch (address->sa_family) { This below block should be moved after the generic switch statement (i.e. once port is checked). > + case AF_UNSPEC: > + /* > + * Connecting to an address with AF_UNSPEC dissolves the TCP > + * association, which have the same effect as closing the > + * connection while retaining the socket object (i.e., the file > + * descriptor). As for dropping privileges, closing > + * connections is always allowed. > + */ > + if (access_request == LANDLOCK_ACCESS_NET_CONNECT_TCP) > + return 0; > + > + /* > + * For compatibility reason, accept AF_UNSPEC for bind > + * accesses (mapped to AF_INET) only if the address is > + * INADDR_ANY (cf. __inet_bind). Checking the address is > + * required to not wrongfully return -EACCES instead of > + * -EAFNOSUPPORT. > + */ > + if (access_request == LANDLOCK_ACCESS_NET_BIND_TCP) { > + const struct sockaddr_in *const sockaddr = > + (struct sockaddr_in *)address; > + > + if (sockaddr->sin_addr.s_addr != htonl(INADDR_ANY)) > + return -EAFNOSUPPORT; > + } > + > + fallthrough; case AF_UNSPEC: > + case AF_INET: if (addrlen < sizeof(struct sockaddr_in)) return -EINVAL; port = ((struct sockaddr_in *)address)->sin_port; break; > +#if IS_ENABLED(CONFIG_IPV6) > + case AF_INET6: if (addrlen < SIN6_LEN_RFC2133) return -EINVAL; port = ((struct sockaddr_in6 *)address)->sin6_port; break; > +#endif /* Allows unhandled protocols. */ default: return 0; } if (address->sa_family == AF_UNSPEC) { // Add here the above AF_UNSPEC checks to be consistent with the EINVAL/EAFNOSUPPORT return ordering. } id.key.data = (__force uintprt_t)port; BUID_BUG_ON(...); > + rule = landlock_find_rule(domain, id); > + handled_access = landlock_init_layer_masks( > + domain, access_request, &layer_masks, > + LANDLOCK_KEY_NET_PORT); > + allowed = landlock_unmask_layers(rule, handled_access, > + &layer_masks, > + ARRAY_SIZE(layer_masks)); > + } This curly brace can now be removed and the following return line is now OK. > + return allowed ? 0 : -EACCES; > +} > + > +static int hook_socket_bind(struct socket *sock, struct sockaddr *address, > + int addrlen) > +{ > + return check_socket_access(sock, address, addrlen, get_port(address), > + LANDLOCK_ACCESS_NET_BIND_TCP); > +} > + > +static int hook_socket_connect(struct socket *sock, struct sockaddr *address, > + int addrlen) > +{ > + return check_socket_access(sock, address, addrlen, get_port(address), > + LANDLOCK_ACCESS_NET_CONNECT_TCP); > +} > + > +static struct security_hook_list landlock_hooks[] __lsm_ro_after_init = { > + LSM_HOOK_INIT(socket_bind, hook_socket_bind), > + LSM_HOOK_INIT(socket_connect, hook_socket_connect), > +}; > + > +__init void landlock_add_net_hooks(void) > +{ > + security_add_hooks(landlock_hooks, ARRAY_SIZE(landlock_hooks), > + LANDLOCK_NAME); > +} > diff --git a/security/landlock/net.h b/security/landlock/net.h > new file mode 100644 > index 000000000000..0da1d9dff5ab > --- /dev/null > +++ b/security/landlock/net.h > @@ -0,0 +1,26 @@ > +/* SPDX-License-Identifier: GPL-2.0-only */ > +/* > + * Landlock LSM - Network management and hooks > + * > + * Copyright © 2022 Huawei Tech. Co., Ltd. > + */ > + > +#ifndef _SECURITY_LANDLOCK_NET_H > +#define _SECURITY_LANDLOCK_NET_H > + > +#include "common.h" > +#include "ruleset.h" > +#include "setup.h" > + > +#if IS_ENABLED(CONFIG_INET) > +__init void landlock_add_net_hooks(void); > + > +int landlock_append_net_rule(struct landlock_ruleset *const ruleset, > + const u16 port, access_mask_t access_rights); > +#else /* IS_ENABLED(CONFIG_INET) */ > +static inline void landlock_add_net_hooks(void) > +{ > +} > +#endif /* IS_ENABLED(CONFIG_INET) */ > + > +#endif /* _SECURITY_LANDLOCK_NET_H */ > diff --git a/security/landlock/ruleset.c b/security/landlock/ruleset.c > index 14207b666095..53cb62701280 100644 > --- a/security/landlock/ruleset.c > +++ b/security/landlock/ruleset.c > @@ -36,6 +36,9 @@ static struct landlock_ruleset *create_ruleset(const u32 num_layers) > refcount_set(&new_ruleset->usage, 1); > mutex_init(&new_ruleset->lock); > new_ruleset->root_inode = RB_ROOT; > +#if IS_ENABLED(CONFIG_INET) > + new_ruleset->root_net_port = RB_ROOT; > +#endif /* IS_ENABLED(CONFIG_INET) */ > new_ruleset->num_layers = num_layers; > /* > * hierarchy = NULL > @@ -46,16 +49,21 @@ static struct landlock_ruleset *create_ruleset(const u32 num_layers) > } > > struct landlock_ruleset * > -landlock_create_ruleset(const access_mask_t fs_access_mask) > +landlock_create_ruleset(const access_mask_t fs_access_mask, > + const access_mask_t net_access_mask) > { > struct landlock_ruleset *new_ruleset; > > /* Informs about useless ruleset. */ > - if (!fs_access_mask) > + if (!fs_access_mask && !net_access_mask) > return ERR_PTR(-ENOMSG); > new_ruleset = create_ruleset(1); > - if (!IS_ERR(new_ruleset)) > + if (IS_ERR(new_ruleset)) > + return new_ruleset; > + if (fs_access_mask) > landlock_add_fs_access_mask(new_ruleset, fs_access_mask, 0); > + if (net_access_mask) > + landlock_add_net_access_mask(new_ruleset, net_access_mask, 0); > return new_ruleset; > } > > @@ -73,6 +81,10 @@ static bool is_object_pointer(const enum landlock_key_type key_type) > switch (key_type) { > case LANDLOCK_KEY_INODE: > return true; > +#if IS_ENABLED(CONFIG_INET) > + case LANDLOCK_KEY_NET_PORT: > + return false; > +#endif /* IS_ENABLED(CONFIG_INET) */ > } > WARN_ON_ONCE(1); > return false; > @@ -126,6 +138,11 @@ static struct rb_root *get_root(struct landlock_ruleset *const ruleset, > case LANDLOCK_KEY_INODE: > root = &ruleset->root_inode; > break; > +#if IS_ENABLED(CONFIG_INET) > + case LANDLOCK_KEY_NET_PORT: > + root = &ruleset->root_net_port; > + break; > +#endif /* IS_ENABLED(CONFIG_INET) */ > } > if (WARN_ON_ONCE(!root)) > return ERR_PTR(-EINVAL); > @@ -154,7 +171,8 @@ static void build_check_ruleset(void) > BUILD_BUG_ON(ruleset.num_rules < LANDLOCK_MAX_NUM_RULES); > BUILD_BUG_ON(ruleset.num_layers < LANDLOCK_MAX_NUM_LAYERS); > BUILD_BUG_ON(access_masks < > - (LANDLOCK_MASK_ACCESS_FS << LANDLOCK_SHIFT_ACCESS_FS)); > + ((LANDLOCK_MASK_ACCESS_FS << LANDLOCK_SHIFT_ACCESS_FS) | > + (LANDLOCK_MASK_ACCESS_NET << LANDLOCK_SHIFT_ACCESS_NET))); > } > > /** > @@ -373,6 +391,12 @@ static int merge_ruleset(struct landlock_ruleset *const dst, > if (err) > goto out_unlock; > > +#if IS_ENABLED(CONFIG_INET) > + /* Merges the @src network port tree. */ > + err = merge_tree(dst, src, LANDLOCK_KEY_NET_PORT); > + if (err) > + goto out_unlock; > +#endif /* IS_ENABLED(CONFIG_INET) */ > out_unlock: > mutex_unlock(&src->lock); > mutex_unlock(&dst->lock); > @@ -429,6 +453,12 @@ static int inherit_ruleset(struct landlock_ruleset *const parent, > if (err) > goto out_unlock; > > +#if IS_ENABLED(CONFIG_INET) > + /* Copies the @parent network port tree. */ > + err = inherit_tree(parent, child, LANDLOCK_KEY_NET_PORT); > + if (err) > + goto out_unlock; > +#endif /* IS_ENABLED(CONFIG_INET) */ > if (WARN_ON_ONCE(child->num_layers <= parent->num_layers)) { > err = -EINVAL; > goto out_unlock; > @@ -461,6 +491,11 @@ static void free_ruleset(struct landlock_ruleset *const ruleset) > rbtree_postorder_for_each_entry_safe(freeme, next, &ruleset->root_inode, > node) > free_rule(freeme, LANDLOCK_KEY_INODE); > +#if IS_ENABLED(CONFIG_INET) > + rbtree_postorder_for_each_entry_safe(freeme, next, > + &ruleset->root_net_port, node) > + free_rule(freeme, LANDLOCK_KEY_NET_PORT); > +#endif /* IS_ENABLED(CONFIG_INET) */ > put_hierarchy(ruleset->hierarchy); > kfree(ruleset); > } > @@ -641,7 +676,8 @@ get_access_mask_t(const struct landlock_ruleset *const ruleset, > * > * @domain: The domain that defines the current restrictions. > * @access_request: The requested access rights to check. > - * @layer_masks: The layer masks to populate. > + * @layer_masks: It must contain LANDLOCK_NUM_ACCESS_FS or LANDLOCK_NUM_ACCESS_NET > + * elements according to @key_type. > * @key_type: The key type to switch between access masks of different types. > * > * Returns: An access mask where each access right bit is set which is handled > @@ -662,6 +698,12 @@ landlock_init_layer_masks(const struct landlock_ruleset *const domain, > get_access_mask = landlock_get_fs_access_mask; > num_access = LANDLOCK_NUM_ACCESS_FS; > break; > +#if IS_ENABLED(CONFIG_INET) > + case LANDLOCK_KEY_NET_PORT: > + get_access_mask = landlock_get_net_access_mask; > + num_access = LANDLOCK_NUM_ACCESS_NET; > + break; > +#endif /* IS_ENABLED(CONFIG_INET) */ > default: > WARN_ON_ONCE(1); > return 0; > diff --git a/security/landlock/ruleset.h b/security/landlock/ruleset.h > index 2251e6048ccf..dcf7fbac8367 100644 > --- a/security/landlock/ruleset.h > +++ b/security/landlock/ruleset.h > @@ -33,13 +33,16 @@ > typedef u16 access_mask_t; > /* Makes sure all filesystem access rights can be stored. */ > static_assert(BITS_PER_TYPE(access_mask_t) >= LANDLOCK_NUM_ACCESS_FS); > +/* Makes sure all network access rights can be stored. */ > +static_assert(BITS_PER_TYPE(access_mask_t) >= LANDLOCK_NUM_ACCESS_NET); > /* Makes sure for_each_set_bit() and for_each_clear_bit() calls are OK. */ > static_assert(sizeof(unsigned long) >= sizeof(access_mask_t)); > > /* Ruleset access masks. */ > -typedef u16 access_masks_t; > +typedef u32 access_masks_t; > /* Makes sure all ruleset access rights can be stored. */ > -static_assert(BITS_PER_TYPE(access_masks_t) >= LANDLOCK_NUM_ACCESS_FS); > +static_assert(BITS_PER_TYPE(access_masks_t) >= > + LANDLOCK_NUM_ACCESS_FS + LANDLOCK_NUM_ACCESS_NET); > > typedef u16 layer_mask_t; > /* Makes sure all layers can be checked. */ > @@ -84,6 +87,13 @@ enum landlock_key_type { > * keys. > */ > LANDLOCK_KEY_INODE = 1, > +#if IS_ENABLED(CONFIG_INET) > + /** > + * @LANDLOCK_KEY_NET_PORT: Type of &landlock_ruleset.root_net_port's > + * node keys. > + */ > + LANDLOCK_KEY_NET_PORT = 2, > +#endif /* IS_ENABLED(CONFIG_INET) */ > }; > > /** > @@ -158,6 +168,15 @@ struct landlock_ruleset { > * reaches zero. > */ > struct rb_root root_inode; > +#if IS_ENABLED(CONFIG_INET) > + /** > + * @root_net_port: Root of a red-black tree containing &struct > + * landlock_rule nodes with network port. Once a ruleset is tied to a > + * process (i.e. as a domain), this tree is immutable until @usage > + * reaches zero. > + */ > + struct rb_root root_net_port; > +#endif /* IS_ENABLED(CONFIG_INET) */ > /** > * @hierarchy: Enables hierarchy identification even when a parent > * domain vanishes. This is needed for the ptrace protection. > @@ -196,13 +215,13 @@ struct landlock_ruleset { > */ > u32 num_layers; > /** > - * @access_masks: Contains the subset of filesystem > - * actions that are restricted by a ruleset. A domain > - * saves all layers of merged rulesets in a stack > - * (FAM), starting from the first layer to the last > - * one. These layers are used when merging rulesets, > - * for user space backward compatibility (i.e. > - * future-proof), and to properly handle merged > + * @access_masks: Contains the subset of filesystem and > + * network actions that are restricted by a ruleset. > + * A domain saves all layers of merged rulesets in a > + * stack (FAM), starting from the first layer to the > + * last one. These layers are used when merging > + * rulesets, for user space backward compatibility > + * (i.e. future-proof), and to properly handle merged > * rulesets without overlapping access rights. These > * layers are set once and never changed for the > * lifetime of the ruleset. > @@ -213,7 +232,8 @@ struct landlock_ruleset { > }; > > struct landlock_ruleset * > -landlock_create_ruleset(const access_mask_t access_mask); > +landlock_create_ruleset(const access_mask_t access_mask_fs, > + const access_mask_t access_mask_net); > > void landlock_put_ruleset(struct landlock_ruleset *const ruleset); > void landlock_put_ruleset_deferred(struct landlock_ruleset *const ruleset); > @@ -249,6 +269,19 @@ landlock_add_fs_access_mask(struct landlock_ruleset *const ruleset, > (fs_mask << LANDLOCK_SHIFT_ACCESS_FS); > } > > +static inline void > +landlock_add_net_access_mask(struct landlock_ruleset *const ruleset, > + const access_mask_t net_access_mask, > + const u16 layer_level) > +{ > + access_mask_t net_mask = net_access_mask & LANDLOCK_MASK_ACCESS_NET; > + > + /* Should already be checked in sys_landlock_create_ruleset(). */ > + WARN_ON_ONCE(net_access_mask != net_mask); > + ruleset->access_masks[layer_level] |= > + (net_mask << LANDLOCK_SHIFT_ACCESS_NET); > +} > + > static inline access_mask_t > landlock_get_raw_fs_access_mask(const struct landlock_ruleset *const ruleset, > const u16 layer_level) > @@ -266,6 +299,16 @@ landlock_get_fs_access_mask(const struct landlock_ruleset *const ruleset, > return landlock_get_raw_fs_access_mask(ruleset, layer_level) | > LANDLOCK_ACCESS_FS_INITIALLY_DENIED; > } > + > +static inline access_mask_t > +landlock_get_net_access_mask(const struct landlock_ruleset *const ruleset, > + const u16 layer_level) > +{ > + return (ruleset->access_masks[layer_level] >> > + LANDLOCK_SHIFT_ACCESS_NET) & > + LANDLOCK_MASK_ACCESS_NET; > +} > + > bool landlock_unmask_layers(const struct landlock_rule *const rule, > const access_mask_t access_request, > layer_mask_t (*const layer_masks)[], > diff --git a/security/landlock/setup.c b/security/landlock/setup.c > index 3f196d2ce4f9..7e4a598177b8 100644 > --- a/security/landlock/setup.c > +++ b/security/landlock/setup.c > @@ -14,6 +14,7 @@ > #include "fs.h" > #include "ptrace.h" > #include "setup.h" > +#include "net.h" > > bool landlock_initialized __lsm_ro_after_init = false; > > @@ -29,6 +30,7 @@ static int __init landlock_init(void) > landlock_add_cred_hooks(); > landlock_add_ptrace_hooks(); > landlock_add_fs_hooks(); > + landlock_add_net_hooks(); > landlock_initialized = true; > pr_info("Up and running.\n"); > return 0; > diff --git a/security/landlock/syscalls.c b/security/landlock/syscalls.c > index 8a54e87dbb17..1f0edd605bc4 100644 > --- a/security/landlock/syscalls.c > +++ b/security/landlock/syscalls.c > @@ -29,6 +29,7 @@ > #include "cred.h" > #include "fs.h" > #include "limits.h" > +#include "net.h" > #include "ruleset.h" > #include "setup.h" > > @@ -74,7 +75,8 @@ static void build_check_abi(void) > { > struct landlock_ruleset_attr ruleset_attr; > struct landlock_path_beneath_attr path_beneath_attr; > - size_t ruleset_size, path_beneath_size; > + struct landlock_net_service_attr net_service_attr; > + size_t ruleset_size, path_beneath_size, net_service_size; > > /* > * For each user space ABI structures, first checks that there is no > @@ -82,13 +84,19 @@ static void build_check_abi(void) > * struct size. > */ > ruleset_size = sizeof(ruleset_attr.handled_access_fs); > + ruleset_size += sizeof(ruleset_attr.handled_access_net); > BUILD_BUG_ON(sizeof(ruleset_attr) != ruleset_size); > - BUILD_BUG_ON(sizeof(ruleset_attr) != 8); > + BUILD_BUG_ON(sizeof(ruleset_attr) != 16); > > path_beneath_size = sizeof(path_beneath_attr.allowed_access); > path_beneath_size += sizeof(path_beneath_attr.parent_fd); > BUILD_BUG_ON(sizeof(path_beneath_attr) != path_beneath_size); > BUILD_BUG_ON(sizeof(path_beneath_attr) != 12); > + > + net_service_size = sizeof(net_service_attr.allowed_access); > + net_service_size += sizeof(net_service_attr.port); > + BUILD_BUG_ON(sizeof(net_service_attr) != net_service_size); > + BUILD_BUG_ON(sizeof(net_service_attr) != 16); > } > > /* Ruleset handling */ > @@ -129,7 +137,7 @@ static const struct file_operations ruleset_fops = { > .write = fop_dummy_write, > }; > > -#define LANDLOCK_ABI_VERSION 3 > +#define LANDLOCK_ABI_VERSION 4 > > /** > * sys_landlock_create_ruleset - Create a new ruleset > @@ -188,8 +196,14 @@ SYSCALL_DEFINE3(landlock_create_ruleset, > LANDLOCK_MASK_ACCESS_FS) > return -EINVAL; > > + /* Checks network content (and 32-bits cast). */ > + if ((ruleset_attr.handled_access_net | LANDLOCK_MASK_ACCESS_NET) != > + LANDLOCK_MASK_ACCESS_NET) > + return -EINVAL; > + > /* Checks arguments and transforms to kernel struct. */ > - ruleset = landlock_create_ruleset(ruleset_attr.handled_access_fs); > + ruleset = landlock_create_ruleset(ruleset_attr.handled_access_fs, > + ruleset_attr.handled_access_net); > if (IS_ERR(ruleset)) > return PTR_ERR(ruleset); > > @@ -315,13 +329,54 @@ static int add_rule_path_beneath(struct landlock_ruleset *const ruleset, > return err; > } > > +static int add_rule_net_service(struct landlock_ruleset *ruleset, > + const void __user *const rule_attr) > +{ > +#if IS_ENABLED(CONFIG_INET) > + struct landlock_net_service_attr net_service_attr; > + int res; > + access_mask_t mask; > + > + /* Copies raw user space buffer, only one type for now. */ > + res = copy_from_user(&net_service_attr, rule_attr, > + sizeof(net_service_attr)); > + if (res) > + return -EFAULT; > + > + /* > + * Informs about useless rule: empty allowed_access (i.e. deny rules) > + * are ignored by network actions. > + */ > + if (!net_service_attr.allowed_access) > + return -ENOMSG; > + > + /* > + * Checks that allowed_access matches the @ruleset constraints > + * (ruleset->access_masks[0] is automatically upgraded to 64-bits). > + */ > + mask = landlock_get_net_access_mask(ruleset, 0); > + if ((net_service_attr.allowed_access | mask) != mask) > + return -EINVAL; > + > + /* Denies inserting a rule with port 0 or more than U16_MAX. */ "Denies inserting a rule with port 0 or higher than 65535." A test should check that it works with 65535 but not with 65536. > + if ((net_service_attr.port == 0) || (net_service_attr.port > U16_MAX)) > + return -EINVAL; > + > + /* Imports the new rule. */ > + return landlock_append_net_rule(ruleset, net_service_attr.port, > + net_service_attr.allowed_access); > +#else /* IS_ENABLED(CONFIG_INET) */ > + return -EAFNOSUPPORT; > +#endif /* IS_ENABLED(CONFIG_INET) */ > +} > + > /** > * sys_landlock_add_rule - Add a new rule to a ruleset > * > * @ruleset_fd: File descriptor tied to the ruleset that should be extended > * with the new rule. > - * @rule_type: Identify the structure type pointed to by @rule_attr (only > - * %LANDLOCK_RULE_PATH_BENEATH for now). > + * @rule_type: Identify the structure type pointed to by @rule_attr: > + * %LANDLOCK_RULE_PATH_BENEATH or %LANDLOCK_RULE_NET_SERVICE. > * @rule_attr: Pointer to a rule (only of type &struct > * landlock_path_beneath_attr for now). > * @flags: Must be 0. > @@ -332,6 +387,8 @@ static int add_rule_path_beneath(struct landlock_ruleset *const ruleset, > * Possible returned errors are: > * > * - %EOPNOTSUPP: Landlock is supported by the kernel but disabled at boot time; > + * - %EAFNOSUPPORT: @rule_type is LANDLOCK_RULE_NET_SERVICE but TCP/IP is not > + * supported by the running kernel; > * - %EINVAL: @flags is not 0, or inconsistent access in the rule (i.e. > * &landlock_path_beneath_attr.allowed_access is not a subset of the > * ruleset handled accesses); > @@ -366,6 +423,9 @@ SYSCALL_DEFINE4(landlock_add_rule, const int, ruleset_fd, > case LANDLOCK_RULE_PATH_BENEATH: > err = add_rule_path_beneath(ruleset, rule_attr); > break; > + case LANDLOCK_RULE_NET_SERVICE: > + err = add_rule_net_service(ruleset, rule_attr); > + break; > default: > err = -EINVAL; > break; > diff --git a/tools/testing/selftests/landlock/base_test.c b/tools/testing/selftests/landlock/base_test.c > index 792c3f0a59b4..646f778dfb1e 100644 > --- a/tools/testing/selftests/landlock/base_test.c > +++ b/tools/testing/selftests/landlock/base_test.c > @@ -75,7 +75,7 @@ TEST(abi_version) > const struct landlock_ruleset_attr ruleset_attr = { > .handled_access_fs = LANDLOCK_ACCESS_FS_READ_FILE, > }; > - ASSERT_EQ(3, landlock_create_ruleset(NULL, 0, > + ASSERT_EQ(4, landlock_create_ruleset(NULL, 0, > LANDLOCK_CREATE_RULESET_VERSION)); > > ASSERT_EQ(-1, landlock_create_ruleset(&ruleset_attr, 0, > -- > 2.25.1 >
4/16/2023 7:11 PM, Mickaël Salaün пишет: > > On 23/03/2023 09:52, Konstantin Meskhidze wrote: >> This commit adds network rules support in the ruleset management >> helpers and the landlock_create_ruleset syscall. >> Refactor user space API to support network actions. Add new network >> access flags, network rule and network attributes. Increment Landlock >> ABI version. Expand access_masks_t to u32 to be sure network access >> rights can be stored. Implement socket_bind() and socket_connect() >> LSM hooks, which enable to restrict TCP socket binding and connection > > "which enables to" > Got it. > >> to specific ports. >> >> Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@huawei.com> >> --- >> >> Changes since v9: >> * Changes UAPI port field to __u64. >> * Moves shared code into check_socket_access(). >> * Adds get_raw_handled_net_accesses() and >> get_current_net_domain() helpers. >> * Minor fixes. >> >> Changes since v8: >> * Squashes commits. >> * Refactors commit message. >> * Changes UAPI port field to __be16. >> * Changes logic of bind/connect hooks with AF_UNSPEC families. >> * Adds address length checking. >> * Minor fixes. >> >> Changes since v7: >> * Squashes commits. >> * Increments ABI version to 4. >> * Refactors commit message. >> * Minor fixes. >> >> Changes since v6: >> * Renames landlock_set_net_access_mask() to landlock_add_net_access_mask() >> because it OR values. >> * Makes landlock_add_net_access_mask() more resilient incorrect values. >> * Refactors landlock_get_net_access_mask(). >> * Renames LANDLOCK_MASK_SHIFT_NET to LANDLOCK_SHIFT_ACCESS_NET and use >> LANDLOCK_NUM_ACCESS_FS as value. >> * Updates access_masks_t to u32 to support network access actions. >> * Refactors landlock internal functions to support network actions with >> landlock_key/key_type/id types. >> >> Changes since v5: >> * Gets rid of partial revert from landlock_add_rule >> syscall. >> * Formats code with clang-format-14. >> >> Changes since v4: >> * Refactors landlock_create_ruleset() - splits ruleset and >> masks checks. >> * Refactors landlock_create_ruleset() and landlock mask >> setters/getters to support two rule types. >> * Refactors landlock_add_rule syscall add_rule_path_beneath >> function by factoring out get_ruleset_from_fd() and >> landlock_put_ruleset(). >> >> Changes since v3: >> * Splits commit. >> * Adds network rule support for internal landlock functions. >> * Adds set_mask and get_mask for network. >> * Adds rb_root root_net_port. >> >> --- >> include/uapi/linux/landlock.h | 49 +++++ >> security/landlock/Kconfig | 1 + >> security/landlock/Makefile | 2 + >> security/landlock/limits.h | 6 +- >> security/landlock/net.c | 198 +++++++++++++++++++ >> security/landlock/net.h | 26 +++ >> security/landlock/ruleset.c | 52 ++++- >> security/landlock/ruleset.h | 63 +++++- >> security/landlock/setup.c | 2 + >> security/landlock/syscalls.c | 72 ++++++- >> tools/testing/selftests/landlock/base_test.c | 2 +- >> 11 files changed, 450 insertions(+), 23 deletions(-) >> create mode 100644 security/landlock/net.c >> create mode 100644 security/landlock/net.h >> >> diff --git a/include/uapi/linux/landlock.h b/include/uapi/linux/landlock.h >> index 81d09ef9aa50..09b70fb6a9a6 100644 >> --- a/include/uapi/linux/landlock.h >> +++ b/include/uapi/linux/landlock.h >> @@ -31,6 +31,13 @@ struct landlock_ruleset_attr { >> * this access right. >> */ >> __u64 handled_access_fs; >> + >> + /** >> + * @handled_access_net: Bitmask of actions (cf. `Network flags`_) >> + * that is handled by this ruleset and should then be forbidden if no >> + * rule explicitly allow them. >> + */ >> + __u64 handled_access_net; >> }; >> >> /* >> @@ -54,6 +61,11 @@ enum landlock_rule_type { >> * landlock_path_beneath_attr . >> */ >> LANDLOCK_RULE_PATH_BENEATH = 1, >> + /** >> + * @LANDLOCK_RULE_NET_SERVICE: Type of a &struct >> + * landlock_net_service_attr . >> + */ >> + LANDLOCK_RULE_NET_SERVICE = 2, >> }; >> >> /** >> @@ -79,6 +91,24 @@ struct landlock_path_beneath_attr { >> */ >> } __attribute__((packed)); >> >> +/** >> + * struct landlock_net_service_attr - TCP subnet definition >> + * >> + * Argument of sys_landlock_add_rule(). >> + */ >> +struct landlock_net_service_attr { >> + /** >> + * @allowed_access: Bitmask of allowed access network for services >> + * (cf. `Network flags`_). >> + */ >> + __u64 allowed_access; >> + /** >> + * @port: Network port. >> + */ >> + __u64 port; >> + >> +} __attribute__((packed)); > > You can remove the empty line and the packed attribute. > Ok. Thanks. > >> + >> /** >> * DOC: fs_access >> * >> @@ -189,4 +219,23 @@ struct landlock_path_beneath_attr { >> #define LANDLOCK_ACCESS_FS_TRUNCATE (1ULL << 14) >> /* clang-format on */ >> >> +/** >> + * DOC: net_access >> + * >> + * Network flags >> + * ~~~~~~~~~~~~~~~~ >> + * >> + * These flags enable to restrict a sandboxed process to a set of network >> + * actions. >> + * >> + * TCP sockets with allowed actions: >> + * >> + * - %LANDLOCK_ACCESS_NET_BIND_TCP: Bind a TCP socket to a local port. >> + * - %LANDLOCK_ACCESS_NET_CONNECT_TCP: Connect an active TCP socket to >> + * a remote port. >> + */ >> +/* clang-format off */ >> +#define LANDLOCK_ACCESS_NET_BIND_TCP (1ULL << 0) >> +#define LANDLOCK_ACCESS_NET_CONNECT_TCP (1ULL << 1) >> +/* clang-format on */ >> #endif /* _UAPI_LINUX_LANDLOCK_H */ >> diff --git a/security/landlock/Kconfig b/security/landlock/Kconfig >> index 8e33c4e8ffb8..10c099097533 100644 >> --- a/security/landlock/Kconfig >> +++ b/security/landlock/Kconfig >> @@ -3,6 +3,7 @@ >> config SECURITY_LANDLOCK >> bool "Landlock support" >> depends on SECURITY && !ARCH_EPHEMERAL_INODES >> + select SECURITY_NETWORK >> select SECURITY_PATH >> help >> Landlock is a sandboxing mechanism that enables processes to restrict >> diff --git a/security/landlock/Makefile b/security/landlock/Makefile >> index 7bbd2f413b3e..53d3c92ae22e 100644 >> --- a/security/landlock/Makefile >> +++ b/security/landlock/Makefile >> @@ -2,3 +2,5 @@ obj-$(CONFIG_SECURITY_LANDLOCK) := landlock.o >> >> landlock-y := setup.o syscalls.o object.o ruleset.o \ >> cred.o ptrace.o fs.o >> + >> +landlock-$(CONFIG_INET) += net.o >> \ No newline at end of file >> diff --git a/security/landlock/limits.h b/security/landlock/limits.h >> index bafb3b8dc677..8a1a6463c64e 100644 >> --- a/security/landlock/limits.h >> +++ b/security/landlock/limits.h >> @@ -23,6 +23,10 @@ >> #define LANDLOCK_NUM_ACCESS_FS __const_hweight64(LANDLOCK_MASK_ACCESS_FS) >> #define LANDLOCK_SHIFT_ACCESS_FS 0 >> >> -/* clang-format on */ >> +#define LANDLOCK_LAST_ACCESS_NET LANDLOCK_ACCESS_NET_CONNECT_TCP >> +#define LANDLOCK_MASK_ACCESS_NET ((LANDLOCK_LAST_ACCESS_NET << 1) - 1) >> +#define LANDLOCK_NUM_ACCESS_NET __const_hweight64(LANDLOCK_MASK_ACCESS_NET) >> +#define LANDLOCK_SHIFT_ACCESS_NET LANDLOCK_NUM_ACCESS_FS >> >> +/* clang-format on */ >> #endif /* _SECURITY_LANDLOCK_LIMITS_H */ >> diff --git a/security/landlock/net.c b/security/landlock/net.c >> new file mode 100644 >> index 000000000000..e19c339906e7 >> --- /dev/null >> +++ b/security/landlock/net.c >> @@ -0,0 +1,198 @@ >> +// SPDX-License-Identifier: GPL-2.0-only >> +/* >> + * Landlock LSM - Network management and hooks >> + * >> + * Copyright © 2022 Huawei Tech. Co., Ltd. >> + * Copyright © 2022 Microsoft Corporation >> + */ >> + >> +#include <linux/in.h> >> +#include <linux/net.h> >> +#include <linux/socket.h> >> +#include <net/ipv6.h> >> + >> +#include "common.h" >> +#include "cred.h" >> +#include "limits.h" >> +#include "net.h" >> +#include "ruleset.h" >> + >> +int landlock_append_net_rule(struct landlock_ruleset *const ruleset, >> + const u16 port, access_mask_t access_rights) >> +{ >> + int err; >> + const struct landlock_id id = { >> + .key.data = port, >> + .type = LANDLOCK_KEY_NET_PORT, >> + }; >> + BUILD_BUG_ON(sizeof(port) > sizeof(id.key.data)); >> + >> + /* Transforms relative access rights to absolute ones. */ >> + access_rights |= LANDLOCK_MASK_ACCESS_NET & >> + ~landlock_get_net_access_mask(ruleset, 0); >> + >> + mutex_lock(&ruleset->lock); >> + err = landlock_insert_rule(ruleset, id, access_rights); >> + mutex_unlock(&ruleset->lock); >> + >> + return err; >> +} >> + >> +static access_mask_t >> +get_raw_handled_net_accesses(const struct landlock_ruleset *const domain) >> +{ >> + access_mask_t access_dom = 0; >> + size_t layer_level; >> + >> + for (layer_level = 0; layer_level < domain->num_layers; layer_level++) >> + access_dom |= landlock_get_net_access_mask(domain, layer_level); >> + return access_dom; >> +} >> + >> +static const struct landlock_ruleset *get_current_net_domain(void) >> +{ >> + const struct landlock_ruleset *const dom = >> + landlock_get_current_domain(); >> + >> + if (!dom || !get_raw_handled_net_accesses(dom)) >> + return NULL; >> + >> + return dom; >> +} >> + >> +static int check_addrlen(const struct sockaddr *const address, int addrlen) >> +{ >> + if (addrlen < offsetofend(struct sockaddr, sa_family)) >> + return -EINVAL; >> + switch (address->sa_family) { >> + case AF_UNSPEC: >> + case AF_INET: >> + if (addrlen < sizeof(struct sockaddr_in)) >> + return -EINVAL; >> + return 0; >> +#if IS_ENABLED(CONFIG_IPV6) >> + case AF_INET6: >> + if (addrlen < SIN6_LEN_RFC2133) >> + return -EINVAL; >> + return 0; >> +#endif >> + } >> + WARN_ON_ONCE(1); >> + return 0; > > With this code, using any non-TCP socket would print a warning. > Yep. Already got this warning printed in tests with unix sockets. I will refactor this part as you suggest below. > All these switch/case make difficult to check consistency across > check_addrlen() and get_port() helpers, they should be inlined into > check_socket_access(), with only one switch statement, but we need to be > careful about the return error orders: first EINVAL and after > EAFNOSUPPORT. Inlining all this also enables to get rid of impossible > cases (that lead to these WARN_ON_ONCE calls). > Got it. Thanks. > > >> +} >> + >> +static u16 get_port(const struct sockaddr *const address) >> +{ >> + /* Gets port value in host byte order. */ >> + switch (address->sa_family) { >> + case AF_UNSPEC: >> + case AF_INET: { >> + const struct sockaddr_in *const sockaddr = >> + (struct sockaddr_in *)address; >> + return ntohs(sockaddr->sin_port); >> + } >> +#if IS_ENABLED(CONFIG_IPV6) >> + case AF_INET6: { >> + const struct sockaddr_in6 *const sockaddr_ip6 = >> + (struct sockaddr_in6 *)address; >> + return ntohs(sockaddr_ip6->sin6_port); >> + } >> +#endif >> + } >> + WARN_ON_ONCE(1); >> + return 0; >> +} >> + >> +static int check_socket_access(struct socket *sock, struct sockaddr *address, int addrlen, u16 port, >> + access_mask_t access_request) >> +{ >> + int ret; >> + bool allowed = false; >> + layer_mask_t layer_masks[LANDLOCK_NUM_ACCESS_NET] = {}; >> + const struct landlock_rule *rule; >> + access_mask_t handled_access; >> + const struct landlock_id id = { >> + .key.data = port, >> + .type = LANDLOCK_KEY_NET_PORT, >> + }; >> + const struct landlock_ruleset *const domain = get_current_net_domain(); >> + >> + if (WARN_ON_ONCE(!domain)) >> + return 0; >> + if (WARN_ON_ONCE(domain->num_layers < 1)) >> + return -EACCES; >> + /* Check if it's a TCP socket. */ >> + if (sock->type != SOCK_STREAM) >> + return 0; >> + >> + ret = check_addrlen(address, addrlen); >> + if (ret) >> + return ret; > > As explained above, this should be replaced with: > > if (addrlen < offsetofend(struct sockaddr, sa_family)) > return -EINVAL; > Ok. > >> + >> + switch (address->sa_family) { > > > This below block should be moved after the generic switch statement > (i.e. once port is checked). > Do you mean checking address family after a port has been checked?? > > >> + case AF_UNSPEC: >> + /* >> + * Connecting to an address with AF_UNSPEC dissolves the TCP >> + * association, which have the same effect as closing the >> + * connection while retaining the socket object (i.e., the file >> + * descriptor). As for dropping privileges, closing >> + * connections is always allowed. >> + */ >> + if (access_request == LANDLOCK_ACCESS_NET_CONNECT_TCP) >> + return 0; >> + >> + /* >> + * For compatibility reason, accept AF_UNSPEC for bind >> + * accesses (mapped to AF_INET) only if the address is >> + * INADDR_ANY (cf. __inet_bind). Checking the address is >> + * required to not wrongfully return -EACCES instead of >> + * -EAFNOSUPPORT. >> + */ >> + if (access_request == LANDLOCK_ACCESS_NET_BIND_TCP) { >> + const struct sockaddr_in *const sockaddr = >> + (struct sockaddr_in *)address; >> + >> + if (sockaddr->sin_addr.s_addr != htonl(INADDR_ANY)) >> + return -EAFNOSUPPORT; >> + } >> + >> + fallthrough; > > > > case AF_UNSPEC: > >> + case AF_INET: > > if (addrlen < sizeof(struct sockaddr_in)) > return -EINVAL; > > port = ((struct sockaddr_in *)address)->sin_port; > break; > > >> +#if IS_ENABLED(CONFIG_IPV6) >> + case AF_INET6: > > if (addrlen < SIN6_LEN_RFC2133) > return -EINVAL; > > port = ((struct sockaddr_in6 *)address)->sin6_port; > break; > > >> +#endif > > /* Allows unhandled protocols. */ > default: > return 0; > } > > if (address->sa_family == AF_UNSPEC) { > > // Add here the above AF_UNSPEC checks to be consistent with the > EINVAL/EAFNOSUPPORT return ordering. > > } > > id.key.data = (__force uintprt_t)port; > BUID_BUG_ON(...); > Will be refactored. Thanks. > > >> + rule = landlock_find_rule(domain, id); >> + handled_access = landlock_init_layer_masks( >> + domain, access_request, &layer_masks, >> + LANDLOCK_KEY_NET_PORT); >> + allowed = landlock_unmask_layers(rule, handled_access, >> + &layer_masks, >> + ARRAY_SIZE(layer_masks)); >> + } > > This curly brace can now be removed and the following return line is now OK. > Ok. Got it. > >> + return allowed ? 0 : -EACCES; >> +} >> + >> +static int hook_socket_bind(struct socket *sock, struct sockaddr *address, >> + int addrlen) >> +{ >> + return check_socket_access(sock, address, addrlen, get_port(address), >> + LANDLOCK_ACCESS_NET_BIND_TCP); >> +} >> + >> +static int hook_socket_connect(struct socket *sock, struct sockaddr *address, >> + int addrlen) >> +{ >> + return check_socket_access(sock, address, addrlen, get_port(address), >> + LANDLOCK_ACCESS_NET_CONNECT_TCP); >> +} >> + >> +static struct security_hook_list landlock_hooks[] __lsm_ro_after_init = { >> + LSM_HOOK_INIT(socket_bind, hook_socket_bind), >> + LSM_HOOK_INIT(socket_connect, hook_socket_connect), >> +}; >> + >> +__init void landlock_add_net_hooks(void) >> +{ >> + security_add_hooks(landlock_hooks, ARRAY_SIZE(landlock_hooks), >> + LANDLOCK_NAME); >> +} >> diff --git a/security/landlock/net.h b/security/landlock/net.h >> new file mode 100644 >> index 000000000000..0da1d9dff5ab >> --- /dev/null >> +++ b/security/landlock/net.h >> @@ -0,0 +1,26 @@ >> +/* SPDX-License-Identifier: GPL-2.0-only */ >> +/* >> + * Landlock LSM - Network management and hooks >> + * >> + * Copyright © 2022 Huawei Tech. Co., Ltd. >> + */ >> + >> +#ifndef _SECURITY_LANDLOCK_NET_H >> +#define _SECURITY_LANDLOCK_NET_H >> + >> +#include "common.h" >> +#include "ruleset.h" >> +#include "setup.h" >> + >> +#if IS_ENABLED(CONFIG_INET) >> +__init void landlock_add_net_hooks(void); >> + >> +int landlock_append_net_rule(struct landlock_ruleset *const ruleset, >> + const u16 port, access_mask_t access_rights); >> +#else /* IS_ENABLED(CONFIG_INET) */ >> +static inline void landlock_add_net_hooks(void) >> +{ >> +} >> +#endif /* IS_ENABLED(CONFIG_INET) */ >> + >> +#endif /* _SECURITY_LANDLOCK_NET_H */ >> diff --git a/security/landlock/ruleset.c b/security/landlock/ruleset.c >> index 14207b666095..53cb62701280 100644 >> --- a/security/landlock/ruleset.c >> +++ b/security/landlock/ruleset.c >> @@ -36,6 +36,9 @@ static struct landlock_ruleset *create_ruleset(const u32 num_layers) >> refcount_set(&new_ruleset->usage, 1); >> mutex_init(&new_ruleset->lock); >> new_ruleset->root_inode = RB_ROOT; >> +#if IS_ENABLED(CONFIG_INET) >> + new_ruleset->root_net_port = RB_ROOT; >> +#endif /* IS_ENABLED(CONFIG_INET) */ >> new_ruleset->num_layers = num_layers; >> /* >> * hierarchy = NULL >> @@ -46,16 +49,21 @@ static struct landlock_ruleset *create_ruleset(const u32 num_layers) >> } >> >> struct landlock_ruleset * >> -landlock_create_ruleset(const access_mask_t fs_access_mask) >> +landlock_create_ruleset(const access_mask_t fs_access_mask, >> + const access_mask_t net_access_mask) >> { >> struct landlock_ruleset *new_ruleset; >> >> /* Informs about useless ruleset. */ >> - if (!fs_access_mask) >> + if (!fs_access_mask && !net_access_mask) >> return ERR_PTR(-ENOMSG); >> new_ruleset = create_ruleset(1); >> - if (!IS_ERR(new_ruleset)) >> + if (IS_ERR(new_ruleset)) >> + return new_ruleset; >> + if (fs_access_mask) >> landlock_add_fs_access_mask(new_ruleset, fs_access_mask, 0); >> + if (net_access_mask) >> + landlock_add_net_access_mask(new_ruleset, net_access_mask, 0); >> return new_ruleset; >> } >> >> @@ -73,6 +81,10 @@ static bool is_object_pointer(const enum landlock_key_type key_type) >> switch (key_type) { >> case LANDLOCK_KEY_INODE: >> return true; >> +#if IS_ENABLED(CONFIG_INET) >> + case LANDLOCK_KEY_NET_PORT: >> + return false; >> +#endif /* IS_ENABLED(CONFIG_INET) */ >> } >> WARN_ON_ONCE(1); >> return false; >> @@ -126,6 +138,11 @@ static struct rb_root *get_root(struct landlock_ruleset *const ruleset, >> case LANDLOCK_KEY_INODE: >> root = &ruleset->root_inode; >> break; >> +#if IS_ENABLED(CONFIG_INET) >> + case LANDLOCK_KEY_NET_PORT: >> + root = &ruleset->root_net_port; >> + break; >> +#endif /* IS_ENABLED(CONFIG_INET) */ >> } >> if (WARN_ON_ONCE(!root)) >> return ERR_PTR(-EINVAL); >> @@ -154,7 +171,8 @@ static void build_check_ruleset(void) >> BUILD_BUG_ON(ruleset.num_rules < LANDLOCK_MAX_NUM_RULES); >> BUILD_BUG_ON(ruleset.num_layers < LANDLOCK_MAX_NUM_LAYERS); >> BUILD_BUG_ON(access_masks < >> - (LANDLOCK_MASK_ACCESS_FS << LANDLOCK_SHIFT_ACCESS_FS)); >> + ((LANDLOCK_MASK_ACCESS_FS << LANDLOCK_SHIFT_ACCESS_FS) | >> + (LANDLOCK_MASK_ACCESS_NET << LANDLOCK_SHIFT_ACCESS_NET))); >> } >> >> /** >> @@ -373,6 +391,12 @@ static int merge_ruleset(struct landlock_ruleset *const dst, >> if (err) >> goto out_unlock; >> >> +#if IS_ENABLED(CONFIG_INET) >> + /* Merges the @src network port tree. */ >> + err = merge_tree(dst, src, LANDLOCK_KEY_NET_PORT); >> + if (err) >> + goto out_unlock; >> +#endif /* IS_ENABLED(CONFIG_INET) */ >> out_unlock: >> mutex_unlock(&src->lock); >> mutex_unlock(&dst->lock); >> @@ -429,6 +453,12 @@ static int inherit_ruleset(struct landlock_ruleset *const parent, >> if (err) >> goto out_unlock; >> >> +#if IS_ENABLED(CONFIG_INET) >> + /* Copies the @parent network port tree. */ >> + err = inherit_tree(parent, child, LANDLOCK_KEY_NET_PORT); >> + if (err) >> + goto out_unlock; >> +#endif /* IS_ENABLED(CONFIG_INET) */ >> if (WARN_ON_ONCE(child->num_layers <= parent->num_layers)) { >> err = -EINVAL; >> goto out_unlock; >> @@ -461,6 +491,11 @@ static void free_ruleset(struct landlock_ruleset *const ruleset) >> rbtree_postorder_for_each_entry_safe(freeme, next, &ruleset->root_inode, >> node) >> free_rule(freeme, LANDLOCK_KEY_INODE); >> +#if IS_ENABLED(CONFIG_INET) >> + rbtree_postorder_for_each_entry_safe(freeme, next, >> + &ruleset->root_net_port, node) >> + free_rule(freeme, LANDLOCK_KEY_NET_PORT); >> +#endif /* IS_ENABLED(CONFIG_INET) */ >> put_hierarchy(ruleset->hierarchy); >> kfree(ruleset); >> } >> @@ -641,7 +676,8 @@ get_access_mask_t(const struct landlock_ruleset *const ruleset, >> * >> * @domain: The domain that defines the current restrictions. >> * @access_request: The requested access rights to check. >> - * @layer_masks: The layer masks to populate. >> + * @layer_masks: It must contain LANDLOCK_NUM_ACCESS_FS or LANDLOCK_NUM_ACCESS_NET >> + * elements according to @key_type. >> * @key_type: The key type to switch between access masks of different types. >> * >> * Returns: An access mask where each access right bit is set which is handled >> @@ -662,6 +698,12 @@ landlock_init_layer_masks(const struct landlock_ruleset *const domain, >> get_access_mask = landlock_get_fs_access_mask; >> num_access = LANDLOCK_NUM_ACCESS_FS; >> break; >> +#if IS_ENABLED(CONFIG_INET) >> + case LANDLOCK_KEY_NET_PORT: >> + get_access_mask = landlock_get_net_access_mask; >> + num_access = LANDLOCK_NUM_ACCESS_NET; >> + break; >> +#endif /* IS_ENABLED(CONFIG_INET) */ >> default: >> WARN_ON_ONCE(1); >> return 0; >> diff --git a/security/landlock/ruleset.h b/security/landlock/ruleset.h >> index 2251e6048ccf..dcf7fbac8367 100644 >> --- a/security/landlock/ruleset.h >> +++ b/security/landlock/ruleset.h >> @@ -33,13 +33,16 @@ >> typedef u16 access_mask_t; >> /* Makes sure all filesystem access rights can be stored. */ >> static_assert(BITS_PER_TYPE(access_mask_t) >= LANDLOCK_NUM_ACCESS_FS); >> +/* Makes sure all network access rights can be stored. */ >> +static_assert(BITS_PER_TYPE(access_mask_t) >= LANDLOCK_NUM_ACCESS_NET); >> /* Makes sure for_each_set_bit() and for_each_clear_bit() calls are OK. */ >> static_assert(sizeof(unsigned long) >= sizeof(access_mask_t)); >> >> /* Ruleset access masks. */ >> -typedef u16 access_masks_t; >> +typedef u32 access_masks_t; >> /* Makes sure all ruleset access rights can be stored. */ >> -static_assert(BITS_PER_TYPE(access_masks_t) >= LANDLOCK_NUM_ACCESS_FS); >> +static_assert(BITS_PER_TYPE(access_masks_t) >= >> + LANDLOCK_NUM_ACCESS_FS + LANDLOCK_NUM_ACCESS_NET); >> >> typedef u16 layer_mask_t; >> /* Makes sure all layers can be checked. */ >> @@ -84,6 +87,13 @@ enum landlock_key_type { >> * keys. >> */ >> LANDLOCK_KEY_INODE = 1, >> +#if IS_ENABLED(CONFIG_INET) >> + /** >> + * @LANDLOCK_KEY_NET_PORT: Type of &landlock_ruleset.root_net_port's >> + * node keys. >> + */ >> + LANDLOCK_KEY_NET_PORT = 2, >> +#endif /* IS_ENABLED(CONFIG_INET) */ >> }; >> >> /** >> @@ -158,6 +168,15 @@ struct landlock_ruleset { >> * reaches zero. >> */ >> struct rb_root root_inode; >> +#if IS_ENABLED(CONFIG_INET) >> + /** >> + * @root_net_port: Root of a red-black tree containing &struct >> + * landlock_rule nodes with network port. Once a ruleset is tied to a >> + * process (i.e. as a domain), this tree is immutable until @usage >> + * reaches zero. >> + */ >> + struct rb_root root_net_port; >> +#endif /* IS_ENABLED(CONFIG_INET) */ >> /** >> * @hierarchy: Enables hierarchy identification even when a parent >> * domain vanishes. This is needed for the ptrace protection. >> @@ -196,13 +215,13 @@ struct landlock_ruleset { >> */ >> u32 num_layers; >> /** >> - * @access_masks: Contains the subset of filesystem >> - * actions that are restricted by a ruleset. A domain >> - * saves all layers of merged rulesets in a stack >> - * (FAM), starting from the first layer to the last >> - * one. These layers are used when merging rulesets, >> - * for user space backward compatibility (i.e. >> - * future-proof), and to properly handle merged >> + * @access_masks: Contains the subset of filesystem and >> + * network actions that are restricted by a ruleset. >> + * A domain saves all layers of merged rulesets in a >> + * stack (FAM), starting from the first layer to the >> + * last one. These layers are used when merging >> + * rulesets, for user space backward compatibility >> + * (i.e. future-proof), and to properly handle merged >> * rulesets without overlapping access rights. These >> * layers are set once and never changed for the >> * lifetime of the ruleset. >> @@ -213,7 +232,8 @@ struct landlock_ruleset { >> }; >> >> struct landlock_ruleset * >> -landlock_create_ruleset(const access_mask_t access_mask); >> +landlock_create_ruleset(const access_mask_t access_mask_fs, >> + const access_mask_t access_mask_net); >> >> void landlock_put_ruleset(struct landlock_ruleset *const ruleset); >> void landlock_put_ruleset_deferred(struct landlock_ruleset *const ruleset); >> @@ -249,6 +269,19 @@ landlock_add_fs_access_mask(struct landlock_ruleset *const ruleset, >> (fs_mask << LANDLOCK_SHIFT_ACCESS_FS); >> } >> >> +static inline void >> +landlock_add_net_access_mask(struct landlock_ruleset *const ruleset, >> + const access_mask_t net_access_mask, >> + const u16 layer_level) >> +{ >> + access_mask_t net_mask = net_access_mask & LANDLOCK_MASK_ACCESS_NET; >> + >> + /* Should already be checked in sys_landlock_create_ruleset(). */ >> + WARN_ON_ONCE(net_access_mask != net_mask); >> + ruleset->access_masks[layer_level] |= >> + (net_mask << LANDLOCK_SHIFT_ACCESS_NET); >> +} >> + >> static inline access_mask_t >> landlock_get_raw_fs_access_mask(const struct landlock_ruleset *const ruleset, >> const u16 layer_level) >> @@ -266,6 +299,16 @@ landlock_get_fs_access_mask(const struct landlock_ruleset *const ruleset, >> return landlock_get_raw_fs_access_mask(ruleset, layer_level) | >> LANDLOCK_ACCESS_FS_INITIALLY_DENIED; >> } >> + >> +static inline access_mask_t >> +landlock_get_net_access_mask(const struct landlock_ruleset *const ruleset, >> + const u16 layer_level) >> +{ >> + return (ruleset->access_masks[layer_level] >> >> + LANDLOCK_SHIFT_ACCESS_NET) & >> + LANDLOCK_MASK_ACCESS_NET; >> +} >> + >> bool landlock_unmask_layers(const struct landlock_rule *const rule, >> const access_mask_t access_request, >> layer_mask_t (*const layer_masks)[], >> diff --git a/security/landlock/setup.c b/security/landlock/setup.c >> index 3f196d2ce4f9..7e4a598177b8 100644 >> --- a/security/landlock/setup.c >> +++ b/security/landlock/setup.c >> @@ -14,6 +14,7 @@ >> #include "fs.h" >> #include "ptrace.h" >> #include "setup.h" >> +#include "net.h" >> >> bool landlock_initialized __lsm_ro_after_init = false; >> >> @@ -29,6 +30,7 @@ static int __init landlock_init(void) >> landlock_add_cred_hooks(); >> landlock_add_ptrace_hooks(); >> landlock_add_fs_hooks(); >> + landlock_add_net_hooks(); >> landlock_initialized = true; >> pr_info("Up and running.\n"); >> return 0; >> diff --git a/security/landlock/syscalls.c b/security/landlock/syscalls.c >> index 8a54e87dbb17..1f0edd605bc4 100644 >> --- a/security/landlock/syscalls.c >> +++ b/security/landlock/syscalls.c >> @@ -29,6 +29,7 @@ >> #include "cred.h" >> #include "fs.h" >> #include "limits.h" >> +#include "net.h" >> #include "ruleset.h" >> #include "setup.h" >> >> @@ -74,7 +75,8 @@ static void build_check_abi(void) >> { >> struct landlock_ruleset_attr ruleset_attr; >> struct landlock_path_beneath_attr path_beneath_attr; >> - size_t ruleset_size, path_beneath_size; >> + struct landlock_net_service_attr net_service_attr; >> + size_t ruleset_size, path_beneath_size, net_service_size; >> >> /* >> * For each user space ABI structures, first checks that there is no >> @@ -82,13 +84,19 @@ static void build_check_abi(void) >> * struct size. >> */ >> ruleset_size = sizeof(ruleset_attr.handled_access_fs); >> + ruleset_size += sizeof(ruleset_attr.handled_access_net); >> BUILD_BUG_ON(sizeof(ruleset_attr) != ruleset_size); >> - BUILD_BUG_ON(sizeof(ruleset_attr) != 8); >> + BUILD_BUG_ON(sizeof(ruleset_attr) != 16); >> >> path_beneath_size = sizeof(path_beneath_attr.allowed_access); >> path_beneath_size += sizeof(path_beneath_attr.parent_fd); >> BUILD_BUG_ON(sizeof(path_beneath_attr) != path_beneath_size); >> BUILD_BUG_ON(sizeof(path_beneath_attr) != 12); >> + >> + net_service_size = sizeof(net_service_attr.allowed_access); >> + net_service_size += sizeof(net_service_attr.port); >> + BUILD_BUG_ON(sizeof(net_service_attr) != net_service_size); >> + BUILD_BUG_ON(sizeof(net_service_attr) != 16); >> } >> >> /* Ruleset handling */ >> @@ -129,7 +137,7 @@ static const struct file_operations ruleset_fops = { >> .write = fop_dummy_write, >> }; >> >> -#define LANDLOCK_ABI_VERSION 3 >> +#define LANDLOCK_ABI_VERSION 4 >> >> /** >> * sys_landlock_create_ruleset - Create a new ruleset >> @@ -188,8 +196,14 @@ SYSCALL_DEFINE3(landlock_create_ruleset, >> LANDLOCK_MASK_ACCESS_FS) >> return -EINVAL; >> >> + /* Checks network content (and 32-bits cast). */ >> + if ((ruleset_attr.handled_access_net | LANDLOCK_MASK_ACCESS_NET) != >> + LANDLOCK_MASK_ACCESS_NET) >> + return -EINVAL; >> + >> /* Checks arguments and transforms to kernel struct. */ >> - ruleset = landlock_create_ruleset(ruleset_attr.handled_access_fs); >> + ruleset = landlock_create_ruleset(ruleset_attr.handled_access_fs, >> + ruleset_attr.handled_access_net); >> if (IS_ERR(ruleset)) >> return PTR_ERR(ruleset); >> >> @@ -315,13 +329,54 @@ static int add_rule_path_beneath(struct landlock_ruleset *const ruleset, >> return err; >> } >> >> +static int add_rule_net_service(struct landlock_ruleset *ruleset, >> + const void __user *const rule_attr) >> +{ >> +#if IS_ENABLED(CONFIG_INET) >> + struct landlock_net_service_attr net_service_attr; >> + int res; >> + access_mask_t mask; >> + >> + /* Copies raw user space buffer, only one type for now. */ >> + res = copy_from_user(&net_service_attr, rule_attr, >> + sizeof(net_service_attr)); >> + if (res) >> + return -EFAULT; >> + >> + /* >> + * Informs about useless rule: empty allowed_access (i.e. deny rules) >> + * are ignored by network actions. >> + */ >> + if (!net_service_attr.allowed_access) >> + return -ENOMSG; >> + >> + /* >> + * Checks that allowed_access matches the @ruleset constraints >> + * (ruleset->access_masks[0] is automatically upgraded to 64-bits). >> + */ >> + mask = landlock_get_net_access_mask(ruleset, 0); >> + if ((net_service_attr.allowed_access | mask) != mask) >> + return -EINVAL; >> + >> + /* Denies inserting a rule with port 0 or more than U16_MAX. */ > "Denies inserting a rule with port 0 or higher than 65535." > > A test should check that it works with 65535 but not with 65536. Got it. > > >> + if ((net_service_attr.port == 0) || (net_service_attr.port > U16_MAX)) >> + return -EINVAL; >> + >> + /* Imports the new rule. */ >> + return landlock_append_net_rule(ruleset, net_service_attr.port, >> + net_service_attr.allowed_access); >> +#else /* IS_ENABLED(CONFIG_INET) */ >> + return -EAFNOSUPPORT; >> +#endif /* IS_ENABLED(CONFIG_INET) */ >> +} >> + >> /** >> * sys_landlock_add_rule - Add a new rule to a ruleset >> * >> * @ruleset_fd: File descriptor tied to the ruleset that should be extended >> * with the new rule. >> - * @rule_type: Identify the structure type pointed to by @rule_attr (only >> - * %LANDLOCK_RULE_PATH_BENEATH for now). >> + * @rule_type: Identify the structure type pointed to by @rule_attr: >> + * %LANDLOCK_RULE_PATH_BENEATH or %LANDLOCK_RULE_NET_SERVICE. >> * @rule_attr: Pointer to a rule (only of type &struct >> * landlock_path_beneath_attr for now). >> * @flags: Must be 0. >> @@ -332,6 +387,8 @@ static int add_rule_path_beneath(struct landlock_ruleset *const ruleset, >> * Possible returned errors are: >> * >> * - %EOPNOTSUPP: Landlock is supported by the kernel but disabled at boot time; >> + * - %EAFNOSUPPORT: @rule_type is LANDLOCK_RULE_NET_SERVICE but TCP/IP is not >> + * supported by the running kernel; >> * - %EINVAL: @flags is not 0, or inconsistent access in the rule (i.e. >> * &landlock_path_beneath_attr.allowed_access is not a subset of the >> * ruleset handled accesses); >> @@ -366,6 +423,9 @@ SYSCALL_DEFINE4(landlock_add_rule, const int, ruleset_fd, >> case LANDLOCK_RULE_PATH_BENEATH: >> err = add_rule_path_beneath(ruleset, rule_attr); >> break; >> + case LANDLOCK_RULE_NET_SERVICE: >> + err = add_rule_net_service(ruleset, rule_attr); >> + break; >> default: >> err = -EINVAL; >> break; >> diff --git a/tools/testing/selftests/landlock/base_test.c b/tools/testing/selftests/landlock/base_test.c >> index 792c3f0a59b4..646f778dfb1e 100644 >> --- a/tools/testing/selftests/landlock/base_test.c >> +++ b/tools/testing/selftests/landlock/base_test.c >> @@ -75,7 +75,7 @@ TEST(abi_version) >> const struct landlock_ruleset_attr ruleset_attr = { >> .handled_access_fs = LANDLOCK_ACCESS_FS_READ_FILE, >> }; >> - ASSERT_EQ(3, landlock_create_ruleset(NULL, 0, >> + ASSERT_EQ(4, landlock_create_ruleset(NULL, 0, >> LANDLOCK_CREATE_RULESET_VERSION)); >> >> ASSERT_EQ(-1, landlock_create_ruleset(&ruleset_attr, 0, >> -- >> 2.25.1 >> > .
On 21/04/2023 11:39, Konstantin Meskhidze (A) wrote: > > > 4/16/2023 7:11 PM, Mickaël Salaün пишет: >> >> On 23/03/2023 09:52, Konstantin Meskhidze wrote: >>> This commit adds network rules support in the ruleset management >>> helpers and the landlock_create_ruleset syscall. >>> Refactor user space API to support network actions. Add new network >>> access flags, network rule and network attributes. Increment Landlock >>> ABI version. Expand access_masks_t to u32 to be sure network access >>> rights can be stored. Implement socket_bind() and socket_connect() >>> LSM hooks, which enable to restrict TCP socket binding and connection >> >> "which enables to" >> > Got it. >> >>> to specific ports. >>> >>> Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@huawei.com> >>> --- [...] >>> +static u16 get_port(const struct sockaddr *const address) >>> +{ >>> + /* Gets port value in host byte order. */ >>> + switch (address->sa_family) { >>> + case AF_UNSPEC: >>> + case AF_INET: { >>> + const struct sockaddr_in *const sockaddr = >>> + (struct sockaddr_in *)address; >>> + return ntohs(sockaddr->sin_port); >>> + } >>> +#if IS_ENABLED(CONFIG_IPV6) >>> + case AF_INET6: { >>> + const struct sockaddr_in6 *const sockaddr_ip6 = >>> + (struct sockaddr_in6 *)address; >>> + return ntohs(sockaddr_ip6->sin6_port); >>> + } >>> +#endif >>> + } >>> + WARN_ON_ONCE(1); >>> + return 0; >>> +} >>> + >>> +static int check_socket_access(struct socket *sock, struct sockaddr *address, int addrlen, u16 port, >>> + access_mask_t access_request) >>> +{ >>> + int ret; >>> + bool allowed = false; >>> + layer_mask_t layer_masks[LANDLOCK_NUM_ACCESS_NET] = {}; >>> + const struct landlock_rule *rule; >>> + access_mask_t handled_access; >>> + const struct landlock_id id = { >>> + .key.data = port, >>> + .type = LANDLOCK_KEY_NET_PORT, >>> + }; >>> + const struct landlock_ruleset *const domain = get_current_net_domain(); >>> + >>> + if (WARN_ON_ONCE(!domain)) >>> + return 0; >>> + if (WARN_ON_ONCE(domain->num_layers < 1)) >>> + return -EACCES; >>> + /* Check if it's a TCP socket. */ >>> + if (sock->type != SOCK_STREAM) >>> + return 0; >>> + >>> + ret = check_addrlen(address, addrlen); >>> + if (ret) >>> + return ret; >> >> As explained above, this should be replaced with: >> >> if (addrlen < offsetofend(struct sockaddr, sa_family)) >> return -EINVAL; >> > Ok. >> >>> + >>> + switch (address->sa_family) { >> >> >> This below block should be moved after the generic switch statement >> (i.e. once port is checked). >> > Do you mean checking address family after a port has been checked?? These specific AF_UNSPEC checks should be in an `if (address->sa_family == AF_UNSPEC)` block after the generic AF_UNSPEC, AF_INET, and AF_INET6 checks in the address->sa_family switch/case, because the checks and errors order must be consistent whatever the sa_family. The AF_UNSPEC checks are really an exception to the AF_INET ones, and should then come after. This may look like this: switch (address->sa_family) { case AF_UNSPEC: case AF_INET: port = ...; break; #if IS_ENABLED(CONFIG_IPV6) case AF_INET6: port = ...; break; #endif default: return 0; } /* Specific AF_UNSPEC handling. */ if (address->sa_family == AF_UNSPEC) { ... if (access_request == LANDLOCK_ACCESS_NET_CONNECT_TCP) return 0; ... } id.key.data = (__force uintptr_t)port; BUILD_BUG_ON(sizeof(port) > sizeof(id.key.data)); rule = landlock_find_rule(domain, id); handled_access = landlock_init_layer_masks( domain, access_request, &layer_masks, LANDLOCK_KEY_NET_PORT); if (landlock_unmask_layers(rule, handled_access, &layer_masks, ARRAY_SIZE(layer_masks))) return 0; return -EACCES; > >> >> >>> + case AF_UNSPEC: >>> + /* >>> + * Connecting to an address with AF_UNSPEC dissolves the TCP >>> + * association, which have the same effect as closing the >>> + * connection while retaining the socket object (i.e., the file >>> + * descriptor). As for dropping privileges, closing >>> + * connections is always allowed. >>> + */ >>> + if (access_request == LANDLOCK_ACCESS_NET_CONNECT_TCP) >>> + return 0; >>> + >>> + /* >>> + * For compatibility reason, accept AF_UNSPEC for bind >>> + * accesses (mapped to AF_INET) only if the address is >>> + * INADDR_ANY (cf. __inet_bind). Checking the address is >>> + * required to not wrongfully return -EACCES instead of >>> + * -EAFNOSUPPORT. >>> + */ >>> + if (access_request == LANDLOCK_ACCESS_NET_BIND_TCP) { >>> + const struct sockaddr_in *const sockaddr = >>> + (struct sockaddr_in *)address; >>> + >>> + if (sockaddr->sin_addr.s_addr != htonl(INADDR_ANY)) >>> + return -EAFNOSUPPORT; >>> + } >>> + >>> + fallthrough; >> >> >> >> case AF_UNSPEC: >> >>> + case AF_INET: >> >> if (addrlen < sizeof(struct sockaddr_in)) >> return -EINVAL; >> >> port = ((struct sockaddr_in *)address)->sin_port; >> break; >> >> >>> +#if IS_ENABLED(CONFIG_IPV6) >>> + case AF_INET6: >> >> if (addrlen < SIN6_LEN_RFC2133) >> return -EINVAL; >> >> port = ((struct sockaddr_in6 *)address)->sin6_port; >> break; >> >> >>> +#endif >> >> /* Allows unhandled protocols. */ >> default: >> return 0; >> } >> >> if (address->sa_family == AF_UNSPEC) { >> >> // Add here the above AF_UNSPEC checks to be consistent with the >> EINVAL/EAFNOSUPPORT return ordering. >> >> } >> >> id.key.data = (__force uintprt_t)port; >> BUID_BUG_ON(...); >> > Will be refactored. Thanks.
diff --git a/include/uapi/linux/landlock.h b/include/uapi/linux/landlock.h index 81d09ef9aa50..09b70fb6a9a6 100644 --- a/include/uapi/linux/landlock.h +++ b/include/uapi/linux/landlock.h @@ -31,6 +31,13 @@ struct landlock_ruleset_attr { * this access right. */ __u64 handled_access_fs; + + /** + * @handled_access_net: Bitmask of actions (cf. `Network flags`_) + * that is handled by this ruleset and should then be forbidden if no + * rule explicitly allow them. + */ + __u64 handled_access_net; }; /* @@ -54,6 +61,11 @@ enum landlock_rule_type { * landlock_path_beneath_attr . */ LANDLOCK_RULE_PATH_BENEATH = 1, + /** + * @LANDLOCK_RULE_NET_SERVICE: Type of a &struct + * landlock_net_service_attr . + */ + LANDLOCK_RULE_NET_SERVICE = 2, }; /** @@ -79,6 +91,24 @@ struct landlock_path_beneath_attr { */ } __attribute__((packed)); +/** + * struct landlock_net_service_attr - TCP subnet definition + * + * Argument of sys_landlock_add_rule(). + */ +struct landlock_net_service_attr { + /** + * @allowed_access: Bitmask of allowed access network for services + * (cf. `Network flags`_). + */ + __u64 allowed_access; + /** + * @port: Network port. + */ + __u64 port; + +} __attribute__((packed)); + /** * DOC: fs_access * @@ -189,4 +219,23 @@ struct landlock_path_beneath_attr { #define LANDLOCK_ACCESS_FS_TRUNCATE (1ULL << 14) /* clang-format on */ +/** + * DOC: net_access + * + * Network flags + * ~~~~~~~~~~~~~~~~ + * + * These flags enable to restrict a sandboxed process to a set of network + * actions. + * + * TCP sockets with allowed actions: + * + * - %LANDLOCK_ACCESS_NET_BIND_TCP: Bind a TCP socket to a local port. + * - %LANDLOCK_ACCESS_NET_CONNECT_TCP: Connect an active TCP socket to + * a remote port. + */ +/* clang-format off */ +#define LANDLOCK_ACCESS_NET_BIND_TCP (1ULL << 0) +#define LANDLOCK_ACCESS_NET_CONNECT_TCP (1ULL << 1) +/* clang-format on */ #endif /* _UAPI_LINUX_LANDLOCK_H */ diff --git a/security/landlock/Kconfig b/security/landlock/Kconfig index 8e33c4e8ffb8..10c099097533 100644 --- a/security/landlock/Kconfig +++ b/security/landlock/Kconfig @@ -3,6 +3,7 @@ config SECURITY_LANDLOCK bool "Landlock support" depends on SECURITY && !ARCH_EPHEMERAL_INODES + select SECURITY_NETWORK select SECURITY_PATH help Landlock is a sandboxing mechanism that enables processes to restrict diff --git a/security/landlock/Makefile b/security/landlock/Makefile index 7bbd2f413b3e..53d3c92ae22e 100644 --- a/security/landlock/Makefile +++ b/security/landlock/Makefile @@ -2,3 +2,5 @@ obj-$(CONFIG_SECURITY_LANDLOCK) := landlock.o landlock-y := setup.o syscalls.o object.o ruleset.o \ cred.o ptrace.o fs.o + +landlock-$(CONFIG_INET) += net.o \ No newline at end of file diff --git a/security/landlock/limits.h b/security/landlock/limits.h index bafb3b8dc677..8a1a6463c64e 100644 --- a/security/landlock/limits.h +++ b/security/landlock/limits.h @@ -23,6 +23,10 @@ #define LANDLOCK_NUM_ACCESS_FS __const_hweight64(LANDLOCK_MASK_ACCESS_FS) #define LANDLOCK_SHIFT_ACCESS_FS 0 -/* clang-format on */ +#define LANDLOCK_LAST_ACCESS_NET LANDLOCK_ACCESS_NET_CONNECT_TCP +#define LANDLOCK_MASK_ACCESS_NET ((LANDLOCK_LAST_ACCESS_NET << 1) - 1) +#define LANDLOCK_NUM_ACCESS_NET __const_hweight64(LANDLOCK_MASK_ACCESS_NET) +#define LANDLOCK_SHIFT_ACCESS_NET LANDLOCK_NUM_ACCESS_FS +/* clang-format on */ #endif /* _SECURITY_LANDLOCK_LIMITS_H */ diff --git a/security/landlock/net.c b/security/landlock/net.c new file mode 100644 index 000000000000..e19c339906e7 --- /dev/null +++ b/security/landlock/net.c @@ -0,0 +1,198 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Landlock LSM - Network management and hooks + * + * Copyright © 2022 Huawei Tech. Co., Ltd. + * Copyright © 2022 Microsoft Corporation + */ + +#include <linux/in.h> +#include <linux/net.h> +#include <linux/socket.h> +#include <net/ipv6.h> + +#include "common.h" +#include "cred.h" +#include "limits.h" +#include "net.h" +#include "ruleset.h" + +int landlock_append_net_rule(struct landlock_ruleset *const ruleset, + const u16 port, access_mask_t access_rights) +{ + int err; + const struct landlock_id id = { + .key.data = port, + .type = LANDLOCK_KEY_NET_PORT, + }; + BUILD_BUG_ON(sizeof(port) > sizeof(id.key.data)); + + /* Transforms relative access rights to absolute ones. */ + access_rights |= LANDLOCK_MASK_ACCESS_NET & + ~landlock_get_net_access_mask(ruleset, 0); + + mutex_lock(&ruleset->lock); + err = landlock_insert_rule(ruleset, id, access_rights); + mutex_unlock(&ruleset->lock); + + return err; +} + +static access_mask_t +get_raw_handled_net_accesses(const struct landlock_ruleset *const domain) +{ + access_mask_t access_dom = 0; + size_t layer_level; + + for (layer_level = 0; layer_level < domain->num_layers; layer_level++) + access_dom |= landlock_get_net_access_mask(domain, layer_level); + return access_dom; +} + +static const struct landlock_ruleset *get_current_net_domain(void) +{ + const struct landlock_ruleset *const dom = + landlock_get_current_domain(); + + if (!dom || !get_raw_handled_net_accesses(dom)) + return NULL; + + return dom; +} + +static int check_addrlen(const struct sockaddr *const address, int addrlen) +{ + if (addrlen < offsetofend(struct sockaddr, sa_family)) + return -EINVAL; + switch (address->sa_family) { + case AF_UNSPEC: + case AF_INET: + if (addrlen < sizeof(struct sockaddr_in)) + return -EINVAL; + return 0; +#if IS_ENABLED(CONFIG_IPV6) + case AF_INET6: + if (addrlen < SIN6_LEN_RFC2133) + return -EINVAL; + return 0; +#endif + } + WARN_ON_ONCE(1); + return 0; +} + +static u16 get_port(const struct sockaddr *const address) +{ + /* Gets port value in host byte order. */ + switch (address->sa_family) { + case AF_UNSPEC: + case AF_INET: { + const struct sockaddr_in *const sockaddr = + (struct sockaddr_in *)address; + return ntohs(sockaddr->sin_port); + } +#if IS_ENABLED(CONFIG_IPV6) + case AF_INET6: { + const struct sockaddr_in6 *const sockaddr_ip6 = + (struct sockaddr_in6 *)address; + return ntohs(sockaddr_ip6->sin6_port); + } +#endif + } + WARN_ON_ONCE(1); + return 0; +} + +static int check_socket_access(struct socket *sock, struct sockaddr *address, int addrlen, u16 port, + access_mask_t access_request) +{ + int ret; + bool allowed = false; + layer_mask_t layer_masks[LANDLOCK_NUM_ACCESS_NET] = {}; + const struct landlock_rule *rule; + access_mask_t handled_access; + const struct landlock_id id = { + .key.data = port, + .type = LANDLOCK_KEY_NET_PORT, + }; + const struct landlock_ruleset *const domain = get_current_net_domain(); + + if (WARN_ON_ONCE(!domain)) + return 0; + if (WARN_ON_ONCE(domain->num_layers < 1)) + return -EACCES; + /* Check if it's a TCP socket. */ + if (sock->type != SOCK_STREAM) + return 0; + + ret = check_addrlen(address, addrlen); + if (ret) + return ret; + + switch (address->sa_family) { + case AF_UNSPEC: + /* + * Connecting to an address with AF_UNSPEC dissolves the TCP + * association, which have the same effect as closing the + * connection while retaining the socket object (i.e., the file + * descriptor). As for dropping privileges, closing + * connections is always allowed. + */ + if (access_request == LANDLOCK_ACCESS_NET_CONNECT_TCP) + return 0; + + /* + * For compatibility reason, accept AF_UNSPEC for bind + * accesses (mapped to AF_INET) only if the address is + * INADDR_ANY (cf. __inet_bind). Checking the address is + * required to not wrongfully return -EACCES instead of + * -EAFNOSUPPORT. + */ + if (access_request == LANDLOCK_ACCESS_NET_BIND_TCP) { + const struct sockaddr_in *const sockaddr = + (struct sockaddr_in *)address; + + if (sockaddr->sin_addr.s_addr != htonl(INADDR_ANY)) + return -EAFNOSUPPORT; + } + + fallthrough; + case AF_INET: +#if IS_ENABLED(CONFIG_IPV6) + case AF_INET6: +#endif + rule = landlock_find_rule(domain, id); + handled_access = landlock_init_layer_masks( + domain, access_request, &layer_masks, + LANDLOCK_KEY_NET_PORT); + allowed = landlock_unmask_layers(rule, handled_access, + &layer_masks, + ARRAY_SIZE(layer_masks)); + } + return allowed ? 0 : -EACCES; +} + +static int hook_socket_bind(struct socket *sock, struct sockaddr *address, + int addrlen) +{ + return check_socket_access(sock, address, addrlen, get_port(address), + LANDLOCK_ACCESS_NET_BIND_TCP); +} + +static int hook_socket_connect(struct socket *sock, struct sockaddr *address, + int addrlen) +{ + return check_socket_access(sock, address, addrlen, get_port(address), + LANDLOCK_ACCESS_NET_CONNECT_TCP); +} + +static struct security_hook_list landlock_hooks[] __lsm_ro_after_init = { + LSM_HOOK_INIT(socket_bind, hook_socket_bind), + LSM_HOOK_INIT(socket_connect, hook_socket_connect), +}; + +__init void landlock_add_net_hooks(void) +{ + security_add_hooks(landlock_hooks, ARRAY_SIZE(landlock_hooks), + LANDLOCK_NAME); +} diff --git a/security/landlock/net.h b/security/landlock/net.h new file mode 100644 index 000000000000..0da1d9dff5ab --- /dev/null +++ b/security/landlock/net.h @@ -0,0 +1,26 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Landlock LSM - Network management and hooks + * + * Copyright © 2022 Huawei Tech. Co., Ltd. + */ + +#ifndef _SECURITY_LANDLOCK_NET_H +#define _SECURITY_LANDLOCK_NET_H + +#include "common.h" +#include "ruleset.h" +#include "setup.h" + +#if IS_ENABLED(CONFIG_INET) +__init void landlock_add_net_hooks(void); + +int landlock_append_net_rule(struct landlock_ruleset *const ruleset, + const u16 port, access_mask_t access_rights); +#else /* IS_ENABLED(CONFIG_INET) */ +static inline void landlock_add_net_hooks(void) +{ +} +#endif /* IS_ENABLED(CONFIG_INET) */ + +#endif /* _SECURITY_LANDLOCK_NET_H */ diff --git a/security/landlock/ruleset.c b/security/landlock/ruleset.c index 14207b666095..53cb62701280 100644 --- a/security/landlock/ruleset.c +++ b/security/landlock/ruleset.c @@ -36,6 +36,9 @@ static struct landlock_ruleset *create_ruleset(const u32 num_layers) refcount_set(&new_ruleset->usage, 1); mutex_init(&new_ruleset->lock); new_ruleset->root_inode = RB_ROOT; +#if IS_ENABLED(CONFIG_INET) + new_ruleset->root_net_port = RB_ROOT; +#endif /* IS_ENABLED(CONFIG_INET) */ new_ruleset->num_layers = num_layers; /* * hierarchy = NULL @@ -46,16 +49,21 @@ static struct landlock_ruleset *create_ruleset(const u32 num_layers) } struct landlock_ruleset * -landlock_create_ruleset(const access_mask_t fs_access_mask) +landlock_create_ruleset(const access_mask_t fs_access_mask, + const access_mask_t net_access_mask) { struct landlock_ruleset *new_ruleset; /* Informs about useless ruleset. */ - if (!fs_access_mask) + if (!fs_access_mask && !net_access_mask) return ERR_PTR(-ENOMSG); new_ruleset = create_ruleset(1); - if (!IS_ERR(new_ruleset)) + if (IS_ERR(new_ruleset)) + return new_ruleset; + if (fs_access_mask) landlock_add_fs_access_mask(new_ruleset, fs_access_mask, 0); + if (net_access_mask) + landlock_add_net_access_mask(new_ruleset, net_access_mask, 0); return new_ruleset; } @@ -73,6 +81,10 @@ static bool is_object_pointer(const enum landlock_key_type key_type) switch (key_type) { case LANDLOCK_KEY_INODE: return true; +#if IS_ENABLED(CONFIG_INET) + case LANDLOCK_KEY_NET_PORT: + return false; +#endif /* IS_ENABLED(CONFIG_INET) */ } WARN_ON_ONCE(1); return false; @@ -126,6 +138,11 @@ static struct rb_root *get_root(struct landlock_ruleset *const ruleset, case LANDLOCK_KEY_INODE: root = &ruleset->root_inode; break; +#if IS_ENABLED(CONFIG_INET) + case LANDLOCK_KEY_NET_PORT: + root = &ruleset->root_net_port; + break; +#endif /* IS_ENABLED(CONFIG_INET) */ } if (WARN_ON_ONCE(!root)) return ERR_PTR(-EINVAL); @@ -154,7 +171,8 @@ static void build_check_ruleset(void) BUILD_BUG_ON(ruleset.num_rules < LANDLOCK_MAX_NUM_RULES); BUILD_BUG_ON(ruleset.num_layers < LANDLOCK_MAX_NUM_LAYERS); BUILD_BUG_ON(access_masks < - (LANDLOCK_MASK_ACCESS_FS << LANDLOCK_SHIFT_ACCESS_FS)); + ((LANDLOCK_MASK_ACCESS_FS << LANDLOCK_SHIFT_ACCESS_FS) | + (LANDLOCK_MASK_ACCESS_NET << LANDLOCK_SHIFT_ACCESS_NET))); } /** @@ -373,6 +391,12 @@ static int merge_ruleset(struct landlock_ruleset *const dst, if (err) goto out_unlock; +#if IS_ENABLED(CONFIG_INET) + /* Merges the @src network port tree. */ + err = merge_tree(dst, src, LANDLOCK_KEY_NET_PORT); + if (err) + goto out_unlock; +#endif /* IS_ENABLED(CONFIG_INET) */ out_unlock: mutex_unlock(&src->lock); mutex_unlock(&dst->lock); @@ -429,6 +453,12 @@ static int inherit_ruleset(struct landlock_ruleset *const parent, if (err) goto out_unlock; +#if IS_ENABLED(CONFIG_INET) + /* Copies the @parent network port tree. */ + err = inherit_tree(parent, child, LANDLOCK_KEY_NET_PORT); + if (err) + goto out_unlock; +#endif /* IS_ENABLED(CONFIG_INET) */ if (WARN_ON_ONCE(child->num_layers <= parent->num_layers)) { err = -EINVAL; goto out_unlock; @@ -461,6 +491,11 @@ static void free_ruleset(struct landlock_ruleset *const ruleset) rbtree_postorder_for_each_entry_safe(freeme, next, &ruleset->root_inode, node) free_rule(freeme, LANDLOCK_KEY_INODE); +#if IS_ENABLED(CONFIG_INET) + rbtree_postorder_for_each_entry_safe(freeme, next, + &ruleset->root_net_port, node) + free_rule(freeme, LANDLOCK_KEY_NET_PORT); +#endif /* IS_ENABLED(CONFIG_INET) */ put_hierarchy(ruleset->hierarchy); kfree(ruleset); } @@ -641,7 +676,8 @@ get_access_mask_t(const struct landlock_ruleset *const ruleset, * * @domain: The domain that defines the current restrictions. * @access_request: The requested access rights to check. - * @layer_masks: The layer masks to populate. + * @layer_masks: It must contain LANDLOCK_NUM_ACCESS_FS or LANDLOCK_NUM_ACCESS_NET + * elements according to @key_type. * @key_type: The key type to switch between access masks of different types. * * Returns: An access mask where each access right bit is set which is handled @@ -662,6 +698,12 @@ landlock_init_layer_masks(const struct landlock_ruleset *const domain, get_access_mask = landlock_get_fs_access_mask; num_access = LANDLOCK_NUM_ACCESS_FS; break; +#if IS_ENABLED(CONFIG_INET) + case LANDLOCK_KEY_NET_PORT: + get_access_mask = landlock_get_net_access_mask; + num_access = LANDLOCK_NUM_ACCESS_NET; + break; +#endif /* IS_ENABLED(CONFIG_INET) */ default: WARN_ON_ONCE(1); return 0; diff --git a/security/landlock/ruleset.h b/security/landlock/ruleset.h index 2251e6048ccf..dcf7fbac8367 100644 --- a/security/landlock/ruleset.h +++ b/security/landlock/ruleset.h @@ -33,13 +33,16 @@ typedef u16 access_mask_t; /* Makes sure all filesystem access rights can be stored. */ static_assert(BITS_PER_TYPE(access_mask_t) >= LANDLOCK_NUM_ACCESS_FS); +/* Makes sure all network access rights can be stored. */ +static_assert(BITS_PER_TYPE(access_mask_t) >= LANDLOCK_NUM_ACCESS_NET); /* Makes sure for_each_set_bit() and for_each_clear_bit() calls are OK. */ static_assert(sizeof(unsigned long) >= sizeof(access_mask_t)); /* Ruleset access masks. */ -typedef u16 access_masks_t; +typedef u32 access_masks_t; /* Makes sure all ruleset access rights can be stored. */ -static_assert(BITS_PER_TYPE(access_masks_t) >= LANDLOCK_NUM_ACCESS_FS); +static_assert(BITS_PER_TYPE(access_masks_t) >= + LANDLOCK_NUM_ACCESS_FS + LANDLOCK_NUM_ACCESS_NET); typedef u16 layer_mask_t; /* Makes sure all layers can be checked. */ @@ -84,6 +87,13 @@ enum landlock_key_type { * keys. */ LANDLOCK_KEY_INODE = 1, +#if IS_ENABLED(CONFIG_INET) + /** + * @LANDLOCK_KEY_NET_PORT: Type of &landlock_ruleset.root_net_port's + * node keys. + */ + LANDLOCK_KEY_NET_PORT = 2, +#endif /* IS_ENABLED(CONFIG_INET) */ }; /** @@ -158,6 +168,15 @@ struct landlock_ruleset { * reaches zero. */ struct rb_root root_inode; +#if IS_ENABLED(CONFIG_INET) + /** + * @root_net_port: Root of a red-black tree containing &struct + * landlock_rule nodes with network port. Once a ruleset is tied to a + * process (i.e. as a domain), this tree is immutable until @usage + * reaches zero. + */ + struct rb_root root_net_port; +#endif /* IS_ENABLED(CONFIG_INET) */ /** * @hierarchy: Enables hierarchy identification even when a parent * domain vanishes. This is needed for the ptrace protection. @@ -196,13 +215,13 @@ struct landlock_ruleset { */ u32 num_layers; /** - * @access_masks: Contains the subset of filesystem - * actions that are restricted by a ruleset. A domain - * saves all layers of merged rulesets in a stack - * (FAM), starting from the first layer to the last - * one. These layers are used when merging rulesets, - * for user space backward compatibility (i.e. - * future-proof), and to properly handle merged + * @access_masks: Contains the subset of filesystem and + * network actions that are restricted by a ruleset. + * A domain saves all layers of merged rulesets in a + * stack (FAM), starting from the first layer to the + * last one. These layers are used when merging + * rulesets, for user space backward compatibility + * (i.e. future-proof), and to properly handle merged * rulesets without overlapping access rights. These * layers are set once and never changed for the * lifetime of the ruleset. @@ -213,7 +232,8 @@ struct landlock_ruleset { }; struct landlock_ruleset * -landlock_create_ruleset(const access_mask_t access_mask); +landlock_create_ruleset(const access_mask_t access_mask_fs, + const access_mask_t access_mask_net); void landlock_put_ruleset(struct landlock_ruleset *const ruleset); void landlock_put_ruleset_deferred(struct landlock_ruleset *const ruleset); @@ -249,6 +269,19 @@ landlock_add_fs_access_mask(struct landlock_ruleset *const ruleset, (fs_mask << LANDLOCK_SHIFT_ACCESS_FS); } +static inline void +landlock_add_net_access_mask(struct landlock_ruleset *const ruleset, + const access_mask_t net_access_mask, + const u16 layer_level) +{ + access_mask_t net_mask = net_access_mask & LANDLOCK_MASK_ACCESS_NET; + + /* Should already be checked in sys_landlock_create_ruleset(). */ + WARN_ON_ONCE(net_access_mask != net_mask); + ruleset->access_masks[layer_level] |= + (net_mask << LANDLOCK_SHIFT_ACCESS_NET); +} + static inline access_mask_t landlock_get_raw_fs_access_mask(const struct landlock_ruleset *const ruleset, const u16 layer_level) @@ -266,6 +299,16 @@ landlock_get_fs_access_mask(const struct landlock_ruleset *const ruleset, return landlock_get_raw_fs_access_mask(ruleset, layer_level) | LANDLOCK_ACCESS_FS_INITIALLY_DENIED; } + +static inline access_mask_t +landlock_get_net_access_mask(const struct landlock_ruleset *const ruleset, + const u16 layer_level) +{ + return (ruleset->access_masks[layer_level] >> + LANDLOCK_SHIFT_ACCESS_NET) & + LANDLOCK_MASK_ACCESS_NET; +} + bool landlock_unmask_layers(const struct landlock_rule *const rule, const access_mask_t access_request, layer_mask_t (*const layer_masks)[], diff --git a/security/landlock/setup.c b/security/landlock/setup.c index 3f196d2ce4f9..7e4a598177b8 100644 --- a/security/landlock/setup.c +++ b/security/landlock/setup.c @@ -14,6 +14,7 @@ #include "fs.h" #include "ptrace.h" #include "setup.h" +#include "net.h" bool landlock_initialized __lsm_ro_after_init = false; @@ -29,6 +30,7 @@ static int __init landlock_init(void) landlock_add_cred_hooks(); landlock_add_ptrace_hooks(); landlock_add_fs_hooks(); + landlock_add_net_hooks(); landlock_initialized = true; pr_info("Up and running.\n"); return 0; diff --git a/security/landlock/syscalls.c b/security/landlock/syscalls.c index 8a54e87dbb17..1f0edd605bc4 100644 --- a/security/landlock/syscalls.c +++ b/security/landlock/syscalls.c @@ -29,6 +29,7 @@ #include "cred.h" #include "fs.h" #include "limits.h" +#include "net.h" #include "ruleset.h" #include "setup.h" @@ -74,7 +75,8 @@ static void build_check_abi(void) { struct landlock_ruleset_attr ruleset_attr; struct landlock_path_beneath_attr path_beneath_attr; - size_t ruleset_size, path_beneath_size; + struct landlock_net_service_attr net_service_attr; + size_t ruleset_size, path_beneath_size, net_service_size; /* * For each user space ABI structures, first checks that there is no @@ -82,13 +84,19 @@ static void build_check_abi(void) * struct size. */ ruleset_size = sizeof(ruleset_attr.handled_access_fs); + ruleset_size += sizeof(ruleset_attr.handled_access_net); BUILD_BUG_ON(sizeof(ruleset_attr) != ruleset_size); - BUILD_BUG_ON(sizeof(ruleset_attr) != 8); + BUILD_BUG_ON(sizeof(ruleset_attr) != 16); path_beneath_size = sizeof(path_beneath_attr.allowed_access); path_beneath_size += sizeof(path_beneath_attr.parent_fd); BUILD_BUG_ON(sizeof(path_beneath_attr) != path_beneath_size); BUILD_BUG_ON(sizeof(path_beneath_attr) != 12); + + net_service_size = sizeof(net_service_attr.allowed_access); + net_service_size += sizeof(net_service_attr.port); + BUILD_BUG_ON(sizeof(net_service_attr) != net_service_size); + BUILD_BUG_ON(sizeof(net_service_attr) != 16); } /* Ruleset handling */ @@ -129,7 +137,7 @@ static const struct file_operations ruleset_fops = { .write = fop_dummy_write, }; -#define LANDLOCK_ABI_VERSION 3 +#define LANDLOCK_ABI_VERSION 4 /** * sys_landlock_create_ruleset - Create a new ruleset @@ -188,8 +196,14 @@ SYSCALL_DEFINE3(landlock_create_ruleset, LANDLOCK_MASK_ACCESS_FS) return -EINVAL; + /* Checks network content (and 32-bits cast). */ + if ((ruleset_attr.handled_access_net | LANDLOCK_MASK_ACCESS_NET) != + LANDLOCK_MASK_ACCESS_NET) + return -EINVAL; + /* Checks arguments and transforms to kernel struct. */ - ruleset = landlock_create_ruleset(ruleset_attr.handled_access_fs); + ruleset = landlock_create_ruleset(ruleset_attr.handled_access_fs, + ruleset_attr.handled_access_net); if (IS_ERR(ruleset)) return PTR_ERR(ruleset); @@ -315,13 +329,54 @@ static int add_rule_path_beneath(struct landlock_ruleset *const ruleset, return err; } +static int add_rule_net_service(struct landlock_ruleset *ruleset, + const void __user *const rule_attr) +{ +#if IS_ENABLED(CONFIG_INET) + struct landlock_net_service_attr net_service_attr; + int res; + access_mask_t mask; + + /* Copies raw user space buffer, only one type for now. */ + res = copy_from_user(&net_service_attr, rule_attr, + sizeof(net_service_attr)); + if (res) + return -EFAULT; + + /* + * Informs about useless rule: empty allowed_access (i.e. deny rules) + * are ignored by network actions. + */ + if (!net_service_attr.allowed_access) + return -ENOMSG; + + /* + * Checks that allowed_access matches the @ruleset constraints + * (ruleset->access_masks[0] is automatically upgraded to 64-bits). + */ + mask = landlock_get_net_access_mask(ruleset, 0); + if ((net_service_attr.allowed_access | mask) != mask) + return -EINVAL; + + /* Denies inserting a rule with port 0 or more than U16_MAX. */ + if ((net_service_attr.port == 0) || (net_service_attr.port > U16_MAX)) + return -EINVAL; + + /* Imports the new rule. */ + return landlock_append_net_rule(ruleset, net_service_attr.port, + net_service_attr.allowed_access); +#else /* IS_ENABLED(CONFIG_INET) */ + return -EAFNOSUPPORT; +#endif /* IS_ENABLED(CONFIG_INET) */ +} + /** * sys_landlock_add_rule - Add a new rule to a ruleset * * @ruleset_fd: File descriptor tied to the ruleset that should be extended * with the new rule. - * @rule_type: Identify the structure type pointed to by @rule_attr (only - * %LANDLOCK_RULE_PATH_BENEATH for now). + * @rule_type: Identify the structure type pointed to by @rule_attr: + * %LANDLOCK_RULE_PATH_BENEATH or %LANDLOCK_RULE_NET_SERVICE. * @rule_attr: Pointer to a rule (only of type &struct * landlock_path_beneath_attr for now). * @flags: Must be 0. @@ -332,6 +387,8 @@ static int add_rule_path_beneath(struct landlock_ruleset *const ruleset, * Possible returned errors are: * * - %EOPNOTSUPP: Landlock is supported by the kernel but disabled at boot time; + * - %EAFNOSUPPORT: @rule_type is LANDLOCK_RULE_NET_SERVICE but TCP/IP is not + * supported by the running kernel; * - %EINVAL: @flags is not 0, or inconsistent access in the rule (i.e. * &landlock_path_beneath_attr.allowed_access is not a subset of the * ruleset handled accesses); @@ -366,6 +423,9 @@ SYSCALL_DEFINE4(landlock_add_rule, const int, ruleset_fd, case LANDLOCK_RULE_PATH_BENEATH: err = add_rule_path_beneath(ruleset, rule_attr); break; + case LANDLOCK_RULE_NET_SERVICE: + err = add_rule_net_service(ruleset, rule_attr); + break; default: err = -EINVAL; break; diff --git a/tools/testing/selftests/landlock/base_test.c b/tools/testing/selftests/landlock/base_test.c index 792c3f0a59b4..646f778dfb1e 100644 --- a/tools/testing/selftests/landlock/base_test.c +++ b/tools/testing/selftests/landlock/base_test.c @@ -75,7 +75,7 @@ TEST(abi_version) const struct landlock_ruleset_attr ruleset_attr = { .handled_access_fs = LANDLOCK_ACCESS_FS_READ_FILE, }; - ASSERT_EQ(3, landlock_create_ruleset(NULL, 0, + ASSERT_EQ(4, landlock_create_ruleset(NULL, 0, LANDLOCK_CREATE_RULESET_VERSION)); ASSERT_EQ(-1, landlock_create_ruleset(&ruleset_attr, 0,
This commit adds network rules support in the ruleset management helpers and the landlock_create_ruleset syscall. Refactor user space API to support network actions. Add new network access flags, network rule and network attributes. Increment Landlock ABI version. Expand access_masks_t to u32 to be sure network access rights can be stored. Implement socket_bind() and socket_connect() LSM hooks, which enable to restrict TCP socket binding and connection to specific ports. Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@huawei.com> --- Changes since v9: * Changes UAPI port field to __u64. * Moves shared code into check_socket_access(). * Adds get_raw_handled_net_accesses() and get_current_net_domain() helpers. * Minor fixes. Changes since v8: * Squashes commits. * Refactors commit message. * Changes UAPI port field to __be16. * Changes logic of bind/connect hooks with AF_UNSPEC families. * Adds address length checking. * Minor fixes. Changes since v7: * Squashes commits. * Increments ABI version to 4. * Refactors commit message. * Minor fixes. Changes since v6: * Renames landlock_set_net_access_mask() to landlock_add_net_access_mask() because it OR values. * Makes landlock_add_net_access_mask() more resilient incorrect values. * Refactors landlock_get_net_access_mask(). * Renames LANDLOCK_MASK_SHIFT_NET to LANDLOCK_SHIFT_ACCESS_NET and use LANDLOCK_NUM_ACCESS_FS as value. * Updates access_masks_t to u32 to support network access actions. * Refactors landlock internal functions to support network actions with landlock_key/key_type/id types. Changes since v5: * Gets rid of partial revert from landlock_add_rule syscall. * Formats code with clang-format-14. Changes since v4: * Refactors landlock_create_ruleset() - splits ruleset and masks checks. * Refactors landlock_create_ruleset() and landlock mask setters/getters to support two rule types. * Refactors landlock_add_rule syscall add_rule_path_beneath function by factoring out get_ruleset_from_fd() and landlock_put_ruleset(). Changes since v3: * Splits commit. * Adds network rule support for internal landlock functions. * Adds set_mask and get_mask for network. * Adds rb_root root_net_port. --- include/uapi/linux/landlock.h | 49 +++++ security/landlock/Kconfig | 1 + security/landlock/Makefile | 2 + security/landlock/limits.h | 6 +- security/landlock/net.c | 198 +++++++++++++++++++ security/landlock/net.h | 26 +++ security/landlock/ruleset.c | 52 ++++- security/landlock/ruleset.h | 63 +++++- security/landlock/setup.c | 2 + security/landlock/syscalls.c | 72 ++++++- tools/testing/selftests/landlock/base_test.c | 2 +- 11 files changed, 450 insertions(+), 23 deletions(-) create mode 100644 security/landlock/net.c create mode 100644 security/landlock/net.h -- 2.25.1