[V4,1/4] security: Add support for SCTP security hooks

The SCTP security hooks are explained in:
Documentation/security/LSM-sctp.rst

Signed-off-by: Richard Haines <richard_c_haines@btinternet.com>
---
 Documentation/security/LSM-sctp.rst | 175 ++++++++++++++++++++++++++++++++++++
 include/linux/lsm_hooks.h           |  36 ++++++++
 include/linux/security.h            |  25 ++++++
 security/security.c                 |  22 +++++
 4 files changed, 258 insertions(+)
 create mode 100644 Documentation/security/LSM-sctp.rst

On Sat, Dec 30, 2017 at 05:19:26PM +0000, Richard Haines wrote:
> The SCTP security hooks are explained in:
> Documentation/security/LSM-sctp.rst
> 
> Signed-off-by: Richard Haines <richard_c_haines@btinternet.com>

Reviewed-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>

> ---
>  Documentation/security/LSM-sctp.rst | 175 ++++++++++++++++++++++++++++++++++++
>  include/linux/lsm_hooks.h           |  36 ++++++++
>  include/linux/security.h            |  25 ++++++
>  security/security.c                 |  22 +++++
>  4 files changed, 258 insertions(+)
>  create mode 100644 Documentation/security/LSM-sctp.rst
> 
> diff --git a/Documentation/security/LSM-sctp.rst b/Documentation/security/LSM-sctp.rst
> new file mode 100644
> index 0000000..6e5a392
> --- /dev/null
> +++ b/Documentation/security/LSM-sctp.rst
> @@ -0,0 +1,175 @@
> +SCTP LSM Support
> +================
> +
> +For security module support, three SCTP specific hooks have been implemented::
> +
> +    security_sctp_assoc_request()
> +    security_sctp_bind_connect()
> +    security_sctp_sk_clone()
> +
> +Also the following security hook has been utilised::
> +
> +    security_inet_conn_established()
> +
> +The usage of these hooks are described below with the SELinux implementation
> +described in ``Documentation/security/SELinux-sctp.rst``
> +
> +
> +security_sctp_assoc_request()
> +-----------------------------
> +Passes the ``@ep`` and ``@chunk->skb`` of the association INIT packet to the
> +security module. Returns 0 on success, error on failure.
> +::
> +
> +    @ep - pointer to sctp endpoint structure.
> +    @skb - pointer to skbuff of association packet.
> +
> +
> +security_sctp_bind_connect()
> +-----------------------------
> +Passes one or more ipv4/ipv6 addresses to the security module for validation
> +based on the ``@optname`` that will result in either a bind or connect
> +service as shown in the permission check tables below.
> +Returns 0 on success, error on failure.
> +::
> +
> +    @sk      - Pointer to sock structure.
> +    @optname - Name of the option to validate.
> +    @address - One or more ipv4 / ipv6 addresses.
> +    @addrlen - The total length of address(s). This is calculated on each
> +               ipv4 or ipv6 address using sizeof(struct sockaddr_in) or
> +               sizeof(struct sockaddr_in6).
> +
> +  ------------------------------------------------------------------
> +  |                     BIND Type Checks                           |
> +  |       @optname             |         @address contains         |
> +  |----------------------------|-----------------------------------|
> +  | SCTP_SOCKOPT_BINDX_ADD     | One or more ipv4 / ipv6 addresses |
> +  | SCTP_PRIMARY_ADDR          | Single ipv4 or ipv6 address       |
> +  | SCTP_SET_PEER_PRIMARY_ADDR | Single ipv4 or ipv6 address       |
> +  ------------------------------------------------------------------
> +
> +  ------------------------------------------------------------------
> +  |                   CONNECT Type Checks                          |
> +  |       @optname             |         @address contains         |
> +  |----------------------------|-----------------------------------|
> +  | SCTP_SOCKOPT_CONNECTX      | One or more ipv4 / ipv6 addresses |
> +  | SCTP_PARAM_ADD_IP          | One or more ipv4 / ipv6 addresses |
> +  | SCTP_SENDMSG_CONNECT       | Single ipv4 or ipv6 address       |
> +  | SCTP_PARAM_SET_PRIMARY     | Single ipv4 or ipv6 address       |
> +  ------------------------------------------------------------------
> +
> +A summary of the ``@optname`` entries is as follows::
> +
> +    SCTP_SOCKOPT_BINDX_ADD - Allows additional bind addresses to be
> +                             associated after (optionally) calling
> +                             bind(3).
> +                             sctp_bindx(3) adds a set of bind
> +                             addresses on a socket.
> +
> +    SCTP_SOCKOPT_CONNECTX - Allows the allocation of multiple
> +                            addresses for reaching a peer
> +                            (multi-homed).
> +                            sctp_connectx(3) initiates a connection
> +                            on an SCTP socket using multiple
> +                            destination addresses.
> +
> +    SCTP_SENDMSG_CONNECT  - Initiate a connection that is generated by a
> +                            sendmsg(2) or sctp_sendmsg(3) on a new asociation.
> +
> +    SCTP_PRIMARY_ADDR     - Set local primary address.
> +
> +    SCTP_SET_PEER_PRIMARY_ADDR - Request peer sets address as
> +                                 association primary.
> +
> +    SCTP_PARAM_ADD_IP          - These are used when Dynamic Address
> +    SCTP_PARAM_SET_PRIMARY     - Reconfiguration is enabled as explained below.
> +
> +
> +To support Dynamic Address Reconfiguration the following parameters must be
> +enabled on both endpoints (or use the appropriate **setsockopt**\(2))::
> +
> +    /proc/sys/net/sctp/addip_enable
> +    /proc/sys/net/sctp/addip_noauth_enable
> +
> +then the following *_PARAM_*'s are sent to the peer in an
> +ASCONF chunk when the corresponding ``@optname``'s are present::
> +
> +          @optname                      ASCONF Parameter
> +         ----------                    ------------------
> +    SCTP_SOCKOPT_BINDX_ADD     ->   SCTP_PARAM_ADD_IP
> +    SCTP_SET_PEER_PRIMARY_ADDR ->   SCTP_PARAM_SET_PRIMARY
> +
> +
> +security_sctp_sk_clone()
> +-------------------------
> +Called whenever a new socket is created by **accept**\(2)
> +(i.e. a TCP style socket) or when a socket is 'peeled off' e.g userspace
> +calls **sctp_peeloff**\(3).
> +::
> +
> +    @ep - pointer to current sctp endpoint structure.
> +    @sk - pointer to current sock structure.
> +    @sk - pointer to new sock structure.
> +
> +
> +security_inet_conn_established()
> +---------------------------------
> +Called when a COOKIE ACK is received::
> +
> +    @sk  - pointer to sock structure.
> +    @skb - pointer to skbuff of the COOKIE ACK packet.
> +
> +
> +Security Hooks used for Association Establishment
> +=================================================
> +The following diagram shows the use of ``security_sctp_bind_connect()``,
> +``security_sctp_assoc_request()``, ``security_inet_conn_established()`` when
> +establishing an association.
> +::
> +
> +      SCTP endpoint "A"                                SCTP endpoint "Z"
> +      =================                                =================
> +    sctp_sf_do_prm_asoc()
> + Association setup can be initiated
> + by a connect(2), sctp_connectx(3),
> + sendmsg(2) or sctp_sendmsg(3).
> + These will result in a call to
> + security_sctp_bind_connect() to
> + initiate an association to
> + SCTP peer endpoint "Z".
> +         INIT --------------------------------------------->
> +                                                   sctp_sf_do_5_1B_init()
> +                                                 Respond to an INIT chunk.
> +                                             SCTP peer endpoint "A" is
> +                                             asking for an association. Call
> +                                             security_sctp_assoc_request()
> +                                             to set the peer label if first
> +                                             association.
> +                                             If not first association, check
> +                                             whether allowed, IF so send:
> +          <----------------------------------------------- INIT ACK
> +          |                                  ELSE audit event and silently
> +          |                                       discard the packet.
> +          |
> +    COOKIE ECHO ------------------------------------------>
> +                                                          |
> +                                                          |
> +                                                          |
> +          <------------------------------------------- COOKIE ACK
> +          |                                               |
> +    sctp_sf_do_5_1E_ca                                    |
> + Call security_inet_conn_established()                    |
> + to set the peer label.                                   |
> +          |                                               |
> +          |                               If SCTP_SOCKET_TCP or peeled off
> +          |                               socket security_sctp_sk_clone() is
> +          |                               called to clone the new socket.
> +          |                                               |
> +      ESTABLISHED                                    ESTABLISHED
> +          |                                               |
> +    ------------------------------------------------------------------
> +    |                     Association Established                    |
> +    ------------------------------------------------------------------
> +
> +
> diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
> index c925812..647e700 100644
> --- a/include/linux/lsm_hooks.h
> +++ b/include/linux/lsm_hooks.h
> @@ -906,6 +906,33 @@
>   *	associated with the TUN device's security structure.
>   *	@security pointer to the TUN devices's security structure.
>   *
> + * Security hooks for SCTP
> + *
> + * @sctp_assoc_request:
> + *	Passes the @ep and @chunk->skb of the association INIT packet to
> + *	the security module.
> + *	@ep pointer to sctp endpoint structure.
> + *	@skb pointer to skbuff of association packet.
> + *	Return 0 on success, error on failure.
> + * @sctp_bind_connect:
> + *	Validiate permissions required for each address associated with sock
> + *	@sk. Depending on @optname, the addresses will be treated as either
> + *	for a connect or bind service. The @addrlen is calculated on each
> + *	ipv4 and ipv6 address using sizeof(struct sockaddr_in) or
> + *	sizeof(struct sockaddr_in6).
> + *	@sk pointer to sock structure.
> + *	@optname name of the option to validate.
> + *	@address list containing one or more ipv4/ipv6 addresses.
> + *	@addrlen total length of address(s).
> + *	Return 0 on success, error on failure.
> + * @sctp_sk_clone:
> + *	Called whenever a new socket is created by accept(2) (i.e. a TCP
> + *	style socket) or when a socket is 'peeled off' e.g userspace
> + *	calls sctp_peeloff(3).
> + *	@ep pointer to current sctp endpoint structure.
> + *	@sk pointer to current sock structure.
> + *	@sk pointer to new sock structure.
> + *
>   * Security hooks for Infiniband
>   *
>   * @ib_pkey_access:
> @@ -1631,6 +1658,12 @@ union security_list_options {
>  	int (*tun_dev_attach_queue)(void *security);
>  	int (*tun_dev_attach)(struct sock *sk, void *security);
>  	int (*tun_dev_open)(void *security);
> +	int (*sctp_assoc_request)(struct sctp_endpoint *ep,
> +				  struct sk_buff *skb);
> +	int (*sctp_bind_connect)(struct sock *sk, int optname,
> +				 struct sockaddr *address, int addrlen);
> +	void (*sctp_sk_clone)(struct sctp_endpoint *ep, struct sock *sk,
> +			      struct sock *newsk);
>  #endif	/* CONFIG_SECURITY_NETWORK */
>  
>  #ifdef CONFIG_SECURITY_INFINIBAND
> @@ -1869,6 +1902,9 @@ struct security_hook_heads {
>  	struct list_head tun_dev_attach_queue;
>  	struct list_head tun_dev_attach;
>  	struct list_head tun_dev_open;
> +	struct list_head sctp_assoc_request;
> +	struct list_head sctp_bind_connect;
> +	struct list_head sctp_sk_clone;
>  #endif	/* CONFIG_SECURITY_NETWORK */
>  #ifdef CONFIG_SECURITY_INFINIBAND
>  	struct list_head ib_pkey_access;
> diff --git a/include/linux/security.h b/include/linux/security.h
> index 3107754..2e5ec5c 100644
> --- a/include/linux/security.h
> +++ b/include/linux/security.h
> @@ -115,6 +115,7 @@ struct xfrm_policy;
>  struct xfrm_state;
>  struct xfrm_user_sec_ctx;
>  struct seq_file;
> +struct sctp_endpoint;
>  
>  #ifdef CONFIG_MMU
>  extern unsigned long mmap_min_addr;
> @@ -1229,6 +1230,11 @@ int security_tun_dev_create(void);
>  int security_tun_dev_attach_queue(void *security);
>  int security_tun_dev_attach(struct sock *sk, void *security);
>  int security_tun_dev_open(void *security);
> +int security_sctp_assoc_request(struct sctp_endpoint *ep, struct sk_buff *skb);
> +int security_sctp_bind_connect(struct sock *sk, int optname,
> +			       struct sockaddr *address, int addrlen);
> +void security_sctp_sk_clone(struct sctp_endpoint *ep, struct sock *sk,
> +			    struct sock *newsk);
>  
>  #else	/* CONFIG_SECURITY_NETWORK */
>  static inline int security_unix_stream_connect(struct sock *sock,
> @@ -1421,6 +1427,25 @@ static inline int security_tun_dev_open(void *security)
>  {
>  	return 0;
>  }
> +
> +static inline int security_sctp_assoc_request(struct sctp_endpoint *ep,
> +					      struct sk_buff *skb)
> +{
> +	return 0;
> +}
> +
> +static inline int security_sctp_bind_connect(struct sock *sk, int optname,
> +					     struct sockaddr *address,
> +					     int addrlen)
> +{
> +	return 0;
> +}
> +
> +static inline void security_sctp_sk_clone(struct sctp_endpoint *ep,
> +					  struct sock *sk,
> +					  struct sock *newsk)
> +{
> +}
>  #endif	/* CONFIG_SECURITY_NETWORK */
>  
>  #ifdef CONFIG_SECURITY_INFINIBAND
> diff --git a/security/security.c b/security/security.c
> index 4bf0f57..1400678 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -1472,6 +1472,7 @@ void security_inet_conn_established(struct sock *sk,
>  {
>  	call_void_hook(inet_conn_established, sk, skb);
>  }
> +EXPORT_SYMBOL(security_inet_conn_established);
>  
>  int security_secmark_relabel_packet(u32 secid)
>  {
> @@ -1527,6 +1528,27 @@ int security_tun_dev_open(void *security)
>  }
>  EXPORT_SYMBOL(security_tun_dev_open);
>  
> +int security_sctp_assoc_request(struct sctp_endpoint *ep, struct sk_buff *skb)
> +{
> +	return call_int_hook(sctp_assoc_request, 0, ep, skb);
> +}
> +EXPORT_SYMBOL(security_sctp_assoc_request);
> +
> +int security_sctp_bind_connect(struct sock *sk, int optname,
> +			       struct sockaddr *address, int addrlen)
> +{
> +	return call_int_hook(sctp_bind_connect, 0, sk, optname,
> +			     address, addrlen);
> +}
> +EXPORT_SYMBOL(security_sctp_bind_connect);
> +
> +void security_sctp_sk_clone(struct sctp_endpoint *ep, struct sock *sk,
> +			    struct sock *newsk)
> +{
> +	call_void_hook(sctp_sk_clone, ep, sk, newsk);
> +}
> +EXPORT_SYMBOL(security_sctp_sk_clone);
> +
>  #endif	/* CONFIG_SECURITY_NETWORK */
>  
>  #ifdef CONFIG_SECURITY_INFINIBAND
> -- 
> 2.14.3
> 
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