| Message ID | 20200625221304.2817194-11-jolsa@kernel.org |
|---|---|
| State | Changes Requested |
| Delegated to: | BPF Maintainers |
| Headers | show |
| Series | bpf: Add d_path helper | expand |
On Thu, Jun 25, 2020 at 4:49 PM Jiri Olsa <jolsa@kernel.org> wrote: > > Adding d_path helper function that returns full path > for give 'struct path' object, which needs to be the > kernel BTF 'path' object. > > The helper calls directly d_path function. > > Updating also bpf.h tools uapi header and adding > 'path' to bpf_helpers_doc.py script. > > Signed-off-by: Jiri Olsa <jolsa@kernel.org> > --- > include/uapi/linux/bpf.h | 14 +++++++++- > kernel/trace/bpf_trace.c | 47 ++++++++++++++++++++++++++++++++++ > scripts/bpf_helpers_doc.py | 2 ++ > tools/include/uapi/linux/bpf.h | 14 +++++++++- > 4 files changed, 75 insertions(+), 2 deletions(-) > > diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h > index 0cb8ec948816..23274c81f244 100644 > --- a/include/uapi/linux/bpf.h > +++ b/include/uapi/linux/bpf.h > @@ -3285,6 +3285,17 @@ union bpf_attr { > * Dynamically cast a *sk* pointer to a *udp6_sock* pointer. > * Return > * *sk* if casting is valid, or NULL otherwise. > + * > + * int bpf_d_path(struct path *path, char *buf, u32 sz) > + * Description > + * Return full path for given 'struct path' object, which > + * needs to be the kernel BTF 'path' object. The path is > + * returned in buffer provided 'buf' of size 'sz'. > + * > + * Return > + * length of returned string on success, or a negative > + * error in case of failure It's important to note whether string is always zero-terminated (I'm guessing it is, right?). > + * > */ > #define __BPF_FUNC_MAPPER(FN) \ > FN(unspec), \ > @@ -3427,7 +3438,8 @@ union bpf_attr { > FN(skc_to_tcp_sock), \ > FN(skc_to_tcp_timewait_sock), \ > FN(skc_to_tcp_request_sock), \ > - FN(skc_to_udp6_sock), > + FN(skc_to_udp6_sock), \ > + FN(d_path), > > /* integer value in 'imm' field of BPF_CALL instruction selects which helper > * function eBPF program intends to call > diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c > index b124d468688c..6f31e21565b6 100644 > --- a/kernel/trace/bpf_trace.c > +++ b/kernel/trace/bpf_trace.c > @@ -1060,6 +1060,51 @@ static const struct bpf_func_proto bpf_send_signal_thread_proto = { > .arg1_type = ARG_ANYTHING, > }; > > +BPF_CALL_3(bpf_d_path, struct path *, path, char *, buf, u32, sz) > +{ > + char *p = d_path(path, buf, sz - 1); > + int len; > + > + if (IS_ERR(p)) { > + len = PTR_ERR(p); > + } else { > + len = strlen(p); > + if (len && p != buf) { > + memmove(buf, p, len); > + buf[len] = 0; if len above is zero, you won't zero-terminate it, so probably better to move buf[len] = 0 out of if to do unconditionally > + } > + } > + > + return len; > +} > + > +BTF_SET_START(btf_whitelist_d_path) > +BTF_ID(func, vfs_truncate) > +BTF_ID(func, vfs_fallocate) > +BTF_ID(func, dentry_open) > +BTF_ID(func, vfs_getattr) > +BTF_ID(func, filp_close) > +BTF_SET_END(btf_whitelist_d_path) > + > +static bool bpf_d_path_allowed(const struct bpf_prog *prog) > +{ > + return btf_id_set_contains(&btf_whitelist_d_path, prog->aux->attach_btf_id); > +} > + This looks pretty great and clean, considering what's happening under the covers. Nice work, thanks a lot! > +BTF_ID_LIST(bpf_d_path_btf_ids) > +BTF_ID(struct, path) this is a bit more confusing to read and error-prone, but I couldn't come up with any better way to do this... Still better than alternatives. > + > +static const struct bpf_func_proto bpf_d_path_proto = { > + .func = bpf_d_path, > + .gpl_only = true, Does it have to be GPL-only? What's the criteria? Sorry if this was brought up previously. > + .ret_type = RET_INTEGER, > + .arg1_type = ARG_PTR_TO_BTF_ID, > + .arg2_type = ARG_PTR_TO_MEM, > + .arg3_type = ARG_CONST_SIZE, > + .btf_id = bpf_d_path_btf_ids, > + .allowed = bpf_d_path_allowed, > +}; > + [...]
On Fri, Jun 26, 2020 at 01:38:27PM -0700, Andrii Nakryiko wrote: > On Thu, Jun 25, 2020 at 4:49 PM Jiri Olsa <jolsa@kernel.org> wrote: > > > > Adding d_path helper function that returns full path > > for give 'struct path' object, which needs to be the > > kernel BTF 'path' object. > > > > The helper calls directly d_path function. > > > > Updating also bpf.h tools uapi header and adding > > 'path' to bpf_helpers_doc.py script. > > > > Signed-off-by: Jiri Olsa <jolsa@kernel.org> > > --- > > include/uapi/linux/bpf.h | 14 +++++++++- > > kernel/trace/bpf_trace.c | 47 ++++++++++++++++++++++++++++++++++ > > scripts/bpf_helpers_doc.py | 2 ++ > > tools/include/uapi/linux/bpf.h | 14 +++++++++- > > 4 files changed, 75 insertions(+), 2 deletions(-) > > > > diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h > > index 0cb8ec948816..23274c81f244 100644 > > --- a/include/uapi/linux/bpf.h > > +++ b/include/uapi/linux/bpf.h > > @@ -3285,6 +3285,17 @@ union bpf_attr { > > * Dynamically cast a *sk* pointer to a *udp6_sock* pointer. > > * Return > > * *sk* if casting is valid, or NULL otherwise. > > + * > > + * int bpf_d_path(struct path *path, char *buf, u32 sz) > > + * Description > > + * Return full path for given 'struct path' object, which > > + * needs to be the kernel BTF 'path' object. The path is > > + * returned in buffer provided 'buf' of size 'sz'. > > + * > > + * Return > > + * length of returned string on success, or a negative > > + * error in case of failure > > It's important to note whether string is always zero-terminated (I'm > guessing it is, right?). right, will add > > > + * > > */ > > #define __BPF_FUNC_MAPPER(FN) \ > > FN(unspec), \ > > @@ -3427,7 +3438,8 @@ union bpf_attr { > > FN(skc_to_tcp_sock), \ > > FN(skc_to_tcp_timewait_sock), \ > > FN(skc_to_tcp_request_sock), \ > > - FN(skc_to_udp6_sock), > > + FN(skc_to_udp6_sock), \ > > + FN(d_path), > > > > /* integer value in 'imm' field of BPF_CALL instruction selects which helper > > * function eBPF program intends to call > > diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c > > index b124d468688c..6f31e21565b6 100644 > > --- a/kernel/trace/bpf_trace.c > > +++ b/kernel/trace/bpf_trace.c > > @@ -1060,6 +1060,51 @@ static const struct bpf_func_proto bpf_send_signal_thread_proto = { > > .arg1_type = ARG_ANYTHING, > > }; > > > > +BPF_CALL_3(bpf_d_path, struct path *, path, char *, buf, u32, sz) > > +{ > > + char *p = d_path(path, buf, sz - 1); > > + int len; > > + > > + if (IS_ERR(p)) { > > + len = PTR_ERR(p); > > + } else { > > + len = strlen(p); > > + if (len && p != buf) { > > + memmove(buf, p, len); > > + buf[len] = 0; > > if len above is zero, you won't zero-terminate it, so probably better > to move buf[len] = 0 out of if to do unconditionally good catch, will change > > > + } > > + } > > + > > + return len; > > +} > > + > > +BTF_SET_START(btf_whitelist_d_path) > > +BTF_ID(func, vfs_truncate) > > +BTF_ID(func, vfs_fallocate) > > +BTF_ID(func, dentry_open) > > +BTF_ID(func, vfs_getattr) > > +BTF_ID(func, filp_close) > > +BTF_SET_END(btf_whitelist_d_path) > > + > > +static bool bpf_d_path_allowed(const struct bpf_prog *prog) > > +{ > > + return btf_id_set_contains(&btf_whitelist_d_path, prog->aux->attach_btf_id); > > +} > > + > > This looks pretty great and clean, considering what's happening under > the covers. Nice work, thanks a lot! > > > +BTF_ID_LIST(bpf_d_path_btf_ids) > > +BTF_ID(struct, path) > > this is a bit more confusing to read and error-prone, but I couldn't > come up with any better way to do this... Still better than > alternatives. > > > + > > +static const struct bpf_func_proto bpf_d_path_proto = { > > + .func = bpf_d_path, > > + .gpl_only = true, > > Does it have to be GPL-only? What's the criteria? Sorry if this was > brought up previously. I don't think it's needed to be gpl_only, I'll set it to false thanks, jirka
On 6/28/20 9:42 PM, Jiri Olsa wrote: > On Fri, Jun 26, 2020 at 01:38:27PM -0700, Andrii Nakryiko wrote: >> On Thu, Jun 25, 2020 at 4:49 PM Jiri Olsa <jolsa@kernel.org> wrote: >>> >>> Adding d_path helper function that returns full path >>> for give 'struct path' object, which needs to be the >>> kernel BTF 'path' object. >>> >>> The helper calls directly d_path function. >>> >>> Updating also bpf.h tools uapi header and adding >>> 'path' to bpf_helpers_doc.py script. >>> >>> Signed-off-by: Jiri Olsa <jolsa@kernel.org> >>> --- >>> include/uapi/linux/bpf.h | 14 +++++++++- >>> kernel/trace/bpf_trace.c | 47 ++++++++++++++++++++++++++++++++++ >>> scripts/bpf_helpers_doc.py | 2 ++ >>> tools/include/uapi/linux/bpf.h | 14 +++++++++- >>> 4 files changed, 75 insertions(+), 2 deletions(-) >>> >>> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h >>> index 0cb8ec948816..23274c81f244 100644 >>> --- a/include/uapi/linux/bpf.h >>> +++ b/include/uapi/linux/bpf.h >>> @@ -3285,6 +3285,17 @@ union bpf_attr { >>> * Dynamically cast a *sk* pointer to a *udp6_sock* pointer. >>> * Return >>> * *sk* if casting is valid, or NULL otherwise. >>> + * >>> + * int bpf_d_path(struct path *path, char *buf, u32 sz) >>> + * Description >>> + * Return full path for given 'struct path' object, which >>> + * needs to be the kernel BTF 'path' object. The path is >>> + * returned in buffer provided 'buf' of size 'sz'. >>> + * >>> + * Return >>> + * length of returned string on success, or a negative >>> + * error in case of failure >> >> It's important to note whether string is always zero-terminated (I'm >> guessing it is, right?). > > right, will add Also note that bpf_probe_read_{kernel, user}_str return the length including the NUL byte: * Return * On success, the strictly positive length of the string, * including the trailing NUL character. On error, a negative * value. It would be good to keep this uniform. So you will need a len += 1 here as well. - KP > >> >>> + * >>> */ >>> #define __BPF_FUNC_MAPPER(FN) \ >>> FN(unspec), \ >>> @@ -3427,7 +3438,8 @@ union bpf_attr { >>> FN(skc_to_tcp_sock), \ >>> FN(skc_to_tcp_timewait_sock), \ >>> FN(skc_to_tcp_request_sock), \ >>> - FN(skc_to_udp6_sock), >>> + FN(skc_to_udp6_sock), \ >>> + FN(d_path), >>> >>> /* integer value in 'imm' field of BPF_CALL instruction selects which helper >>> * function eBPF program intends to call >>> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c >>> index b124d468688c..6f31e21565b6 100644 >>> --- a/kernel/trace/bpf_trace.c >>> +++ b/kernel/trace/bpf_trace.c >>> @@ -1060,6 +1060,51 @@ static const struct bpf_func_proto bpf_send_signal_thread_proto = { >>> .arg1_type = ARG_ANYTHING, >>> }; >>> >>> +BPF_CALL_3(bpf_d_path, struct path *, path, char *, buf, u32, sz) >>> +{ >>> + char *p = d_path(path, buf, sz - 1); >>> + int len; >>> + >>> + if (IS_ERR(p)) { >>> + len = PTR_ERR(p); >>> + } else { >>> + len = strlen(p); >>> + if (len && p != buf) { >>> + memmove(buf, p, len); >>> + buf[len] = 0; >> >> if len above is zero, you won't zero-terminate it, so probably better >> to move buf[len] = 0 out of if to do unconditionally > > good catch, will change > >> >>> + } >>> + } >>> + >>> + return len; >>> +} >>> + >>> +BTF_SET_START(btf_whitelist_d_path) >>> +BTF_ID(func, vfs_truncate) >>> +BTF_ID(func, vfs_fallocate) >>> +BTF_ID(func, dentry_open) >>> +BTF_ID(func, vfs_getattr) >>> +BTF_ID(func, filp_close) >>> +BTF_SET_END(btf_whitelist_d_path) >>> + >>> +static bool bpf_d_path_allowed(const struct bpf_prog *prog) >>> +{ >>> + return btf_id_set_contains(&btf_whitelist_d_path, prog->aux->attach_btf_id); >>> +} >>> + >> >> This looks pretty great and clean, considering what's happening under >> the covers. Nice work, thanks a lot! >> >>> +BTF_ID_LIST(bpf_d_path_btf_ids) >>> +BTF_ID(struct, path) >> >> this is a bit more confusing to read and error-prone, but I couldn't >> come up with any better way to do this... Still better than >> alternatives. >> >>> + >>> +static const struct bpf_func_proto bpf_d_path_proto = { >>> + .func = bpf_d_path, >>> + .gpl_only = true, >> >> Does it have to be GPL-only? What's the criteria? Sorry if this was >> brought up previously. > > I don't think it's needed to be gpl_only, I'll set it to false > > thanks, > jirka >
On Fri, Jul 17, 2020 at 01:13:23AM +0200, KP Singh wrote: > > > On 6/28/20 9:42 PM, Jiri Olsa wrote: > > On Fri, Jun 26, 2020 at 01:38:27PM -0700, Andrii Nakryiko wrote: > >> On Thu, Jun 25, 2020 at 4:49 PM Jiri Olsa <jolsa@kernel.org> wrote: > >>> > >>> Adding d_path helper function that returns full path > >>> for give 'struct path' object, which needs to be the > >>> kernel BTF 'path' object. > >>> > >>> The helper calls directly d_path function. > >>> > >>> Updating also bpf.h tools uapi header and adding > >>> 'path' to bpf_helpers_doc.py script. > >>> > >>> Signed-off-by: Jiri Olsa <jolsa@kernel.org> > >>> --- > >>> include/uapi/linux/bpf.h | 14 +++++++++- > >>> kernel/trace/bpf_trace.c | 47 ++++++++++++++++++++++++++++++++++ > >>> scripts/bpf_helpers_doc.py | 2 ++ > >>> tools/include/uapi/linux/bpf.h | 14 +++++++++- > >>> 4 files changed, 75 insertions(+), 2 deletions(-) > >>> > >>> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h > >>> index 0cb8ec948816..23274c81f244 100644 > >>> --- a/include/uapi/linux/bpf.h > >>> +++ b/include/uapi/linux/bpf.h > >>> @@ -3285,6 +3285,17 @@ union bpf_attr { > >>> * Dynamically cast a *sk* pointer to a *udp6_sock* pointer. > >>> * Return > >>> * *sk* if casting is valid, or NULL otherwise. > >>> + * > >>> + * int bpf_d_path(struct path *path, char *buf, u32 sz) > >>> + * Description > >>> + * Return full path for given 'struct path' object, which > >>> + * needs to be the kernel BTF 'path' object. The path is > >>> + * returned in buffer provided 'buf' of size 'sz'. > >>> + * > >>> + * Return > >>> + * length of returned string on success, or a negative > >>> + * error in case of failure > >> > >> It's important to note whether string is always zero-terminated (I'm > >> guessing it is, right?). > > > > right, will add > > Also note that bpf_probe_read_{kernel, user}_str return the length including > the NUL byte: > > * Return > * On success, the strictly positive length of the string, > * including the trailing NUL character. On error, a negative > * value. > > It would be good to keep this uniform. So you will need a len += 1 here as well. good point, will keep it that way thanks, jirka
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 0cb8ec948816..23274c81f244 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -3285,6 +3285,17 @@ union bpf_attr { * Dynamically cast a *sk* pointer to a *udp6_sock* pointer. * Return * *sk* if casting is valid, or NULL otherwise. + * + * int bpf_d_path(struct path *path, char *buf, u32 sz) + * Description + * Return full path for given 'struct path' object, which + * needs to be the kernel BTF 'path' object. The path is + * returned in buffer provided 'buf' of size 'sz'. + * + * Return + * length of returned string on success, or a negative + * error in case of failure + * */ #define __BPF_FUNC_MAPPER(FN) \ FN(unspec), \ @@ -3427,7 +3438,8 @@ union bpf_attr { FN(skc_to_tcp_sock), \ FN(skc_to_tcp_timewait_sock), \ FN(skc_to_tcp_request_sock), \ - FN(skc_to_udp6_sock), + FN(skc_to_udp6_sock), \ + FN(d_path), /* integer value in 'imm' field of BPF_CALL instruction selects which helper * function eBPF program intends to call diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index b124d468688c..6f31e21565b6 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -1060,6 +1060,51 @@ static const struct bpf_func_proto bpf_send_signal_thread_proto = { .arg1_type = ARG_ANYTHING, }; +BPF_CALL_3(bpf_d_path, struct path *, path, char *, buf, u32, sz) +{ + char *p = d_path(path, buf, sz - 1); + int len; + + if (IS_ERR(p)) { + len = PTR_ERR(p); + } else { + len = strlen(p); + if (len && p != buf) { + memmove(buf, p, len); + buf[len] = 0; + } + } + + return len; +} + +BTF_SET_START(btf_whitelist_d_path) +BTF_ID(func, vfs_truncate) +BTF_ID(func, vfs_fallocate) +BTF_ID(func, dentry_open) +BTF_ID(func, vfs_getattr) +BTF_ID(func, filp_close) +BTF_SET_END(btf_whitelist_d_path) + +static bool bpf_d_path_allowed(const struct bpf_prog *prog) +{ + return btf_id_set_contains(&btf_whitelist_d_path, prog->aux->attach_btf_id); +} + +BTF_ID_LIST(bpf_d_path_btf_ids) +BTF_ID(struct, path) + +static const struct bpf_func_proto bpf_d_path_proto = { + .func = bpf_d_path, + .gpl_only = true, + .ret_type = RET_INTEGER, + .arg1_type = ARG_PTR_TO_BTF_ID, + .arg2_type = ARG_PTR_TO_MEM, + .arg3_type = ARG_CONST_SIZE, + .btf_id = bpf_d_path_btf_ids, + .allowed = bpf_d_path_allowed, +}; + const struct bpf_func_proto * bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) { @@ -1539,6 +1584,8 @@ tracing_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) return prog->expected_attach_type == BPF_TRACE_ITER ? &bpf_seq_write_proto : NULL; + case BPF_FUNC_d_path: + return &bpf_d_path_proto; default: return raw_tp_prog_func_proto(func_id, prog); } diff --git a/scripts/bpf_helpers_doc.py b/scripts/bpf_helpers_doc.py index 6bab40ff442e..bacc0a2856c7 100755 --- a/scripts/bpf_helpers_doc.py +++ b/scripts/bpf_helpers_doc.py @@ -430,6 +430,7 @@ class PrinterHelpers(Printer): 'struct __sk_buff', 'struct sk_msg_md', 'struct xdp_md', + 'struct path', ] known_types = { '...', @@ -468,6 +469,7 @@ class PrinterHelpers(Printer): 'struct tcp_timewait_sock', 'struct tcp_request_sock', 'struct udp6_sock', + 'struct path', } mapped_types = { 'u8': '__u8', diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index 0cb8ec948816..23274c81f244 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -3285,6 +3285,17 @@ union bpf_attr { * Dynamically cast a *sk* pointer to a *udp6_sock* pointer. * Return * *sk* if casting is valid, or NULL otherwise. + * + * int bpf_d_path(struct path *path, char *buf, u32 sz) + * Description + * Return full path for given 'struct path' object, which + * needs to be the kernel BTF 'path' object. The path is + * returned in buffer provided 'buf' of size 'sz'. + * + * Return + * length of returned string on success, or a negative + * error in case of failure + * */ #define __BPF_FUNC_MAPPER(FN) \ FN(unspec), \ @@ -3427,7 +3438,8 @@ union bpf_attr { FN(skc_to_tcp_sock), \ FN(skc_to_tcp_timewait_sock), \ FN(skc_to_tcp_request_sock), \ - FN(skc_to_udp6_sock), + FN(skc_to_udp6_sock), \ + FN(d_path), /* integer value in 'imm' field of BPF_CALL instruction selects which helper * function eBPF program intends to call
Adding d_path helper function that returns full path for give 'struct path' object, which needs to be the kernel BTF 'path' object. The helper calls directly d_path function. Updating also bpf.h tools uapi header and adding 'path' to bpf_helpers_doc.py script. Signed-off-by: Jiri Olsa <jolsa@kernel.org> --- include/uapi/linux/bpf.h | 14 +++++++++- kernel/trace/bpf_trace.c | 47 ++++++++++++++++++++++++++++++++++ scripts/bpf_helpers_doc.py | 2 ++ tools/include/uapi/linux/bpf.h | 14 +++++++++- 4 files changed, 75 insertions(+), 2 deletions(-)