security: add sctp_assoc_established hook

security_sctp_assoc_established() is added to replace
security_inet_conn_established() called in
sctp_sf_do_5_1E_ca(), so that asoc can be accessed in security
subsystem and save the peer secid to asoc->peer_secid.

Fixes: 72e89f5008 ("security: Add support for SCTP security hooks")
Reported-by: Prashanth Prahlad <pprahlad@redhat.com>
Based-on-patch-by: Xin Long <lucien.xin@gmail.com>
Reviewed-by: Xin Long <lucien.xin@gmail.com>
Tested-by: Richard Haines <richard_c_haines@btinternet.com>
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>

Documentation/security/SCTP.rst

@@ -15,10 +15,7 @@ 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()
+    security_sctp_assoc_established()
 
 The usage of these hooks are described below with the SELinux implementation
 described in the `SCTP SELinux Support`_ chapter.
@@ -122,11 +119,12 @@ calls **sctp_peeloff**\(3).
     @newsk - pointer to new sock structure.
 
 
-security_inet_conn_established()
+security_sctp_assoc_established()
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-Called when a COOKIE ACK is received::
+Called when a COOKIE ACK is received, and the peer secid will be
+saved into ``@asoc->peer_secid`` for client::
 
-    @sk  - pointer to sock structure.
+    @asoc - pointer to sctp association structure.
     @skb - pointer to skbuff of the COOKIE ACK packet.
 
 
@@ -134,7 +132,7 @@ 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
+``security_sctp_assoc_request()``, ``security_sctp_assoc_established()`` when
 establishing an association.
 ::
 
@@ -172,7 +170,7 @@ establishing an association.
           <------------------------------------------- COOKIE ACK
           |                                               |
     sctp_sf_do_5_1E_ca                                    |
- Call security_inet_conn_established()                    |
+ Call security_sctp_assoc_established()                   |
  to set the peer label.                                   |
           |                                               |
           |                               If SCTP_SOCKET_TCP or peeled off
@@ -198,7 +196,7 @@ hooks with the SELinux specifics expanded below::
     security_sctp_assoc_request()
     security_sctp_bind_connect()
     security_sctp_sk_clone()
-    security_inet_conn_established()
+    security_sctp_assoc_established()
 
 
 security_sctp_assoc_request()
@@ -271,12 +269,12 @@ sockets sid and peer sid to that contained in the ``@asoc sid`` and
     @newsk - pointer to new sock structure.
 
 
-security_inet_conn_established()
+security_sctp_assoc_established()
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 Called when a COOKIE ACK is received where it sets the connection's peer sid
 to that in ``@skb``::
 
-    @sk  - pointer to sock structure.
+    @asoc - pointer to sctp association structure.
     @skb - pointer to skbuff of the COOKIE ACK packet.
 
 

include/linux/lsm_hook_defs.h

@@ -332,6 +332,8 @@ LSM_HOOK(int, 0, sctp_bind_connect, struct sock *sk, int optname,
 	 struct sockaddr *address, int addrlen)
 LSM_HOOK(void, LSM_RET_VOID, sctp_sk_clone, struct sctp_association *asoc,
 	 struct sock *sk, struct sock *newsk)
+LSM_HOOK(int, 0, sctp_assoc_established, struct sctp_association *asoc,
+	 struct sk_buff *skb)
 #endif /* CONFIG_SECURITY_NETWORK */
 
 #ifdef CONFIG_SECURITY_INFINIBAND

include/linux/lsm_hooks.h

@@ -1046,6 +1046,11 @@
  *	@asoc pointer to current sctp association structure.
  *	@sk pointer to current sock structure.
  *	@newsk pointer to new sock structure.
+ * @sctp_assoc_established:
+ *	Passes the @asoc and @chunk->skb of the association COOKIE_ACK packet
+ *	to the security module.
+ *	@asoc pointer to sctp association structure.
+ *	@skb pointer to skbuff of association packet.
  *
  * Security hooks for Infiniband
  *

include/linux/security.h

@@ -1422,6 +1422,8 @@ int security_sctp_bind_connect(struct sock *sk, int optname,
 			       struct sockaddr *address, int addrlen);
 void security_sctp_sk_clone(struct sctp_association *asoc, struct sock *sk,
 			    struct sock *newsk);
+int security_sctp_assoc_established(struct sctp_association *asoc,
+				    struct sk_buff *skb);
 
 #else	/* CONFIG_SECURITY_NETWORK */
 static inline int security_unix_stream_connect(struct sock *sock,
@@ -1641,6 +1643,12 @@ static inline void security_sctp_sk_clone(struct sctp_association *asoc,
 					  struct sock *newsk)
 {
 }
+
+static inline int security_sctp_assoc_established(struct sctp_association *asoc,
+						  struct sk_buff *skb)
+{
+	return 0;
+}
 #endif	/* CONFIG_SECURITY_NETWORK */
 
 #ifdef CONFIG_SECURITY_INFINIBAND

net/sctp/sm_statefuns.c

@@ -930,6 +930,11 @@ enum sctp_disposition sctp_sf_do_5_1E_ca(struct net *net,
 	if (!sctp_vtag_verify(chunk, asoc))
 		return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
 
+	/* Set peer label for connection. */
+	if (security_sctp_assoc_established((struct sctp_association *)asoc,
+					    chunk->skb))
+		return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
+
 	/* Verify that the chunk length for the COOKIE-ACK is OK.
 	 * If we don't do this, any bundled chunks may be junked.
 	 */
@@ -945,9 +950,6 @@ enum sctp_disposition sctp_sf_do_5_1E_ca(struct net *net,
 	 */
 	sctp_add_cmd_sf(commands, SCTP_CMD_INIT_COUNTER_RESET, SCTP_NULL());
 
-	/* Set peer label for connection. */
-	security_inet_conn_established(ep->base.sk, chunk->skb);
-
 	/* RFC 2960 5.1 Normal Establishment of an Association
 	 *
 	 * E) Upon reception of the COOKIE ACK, endpoint "A" will move

security/security.c

@@ -2393,6 +2393,13 @@ void security_sctp_sk_clone(struct sctp_association *asoc, struct sock *sk,
 }
 EXPORT_SYMBOL(security_sctp_sk_clone);
 
+int security_sctp_assoc_established(struct sctp_association *asoc,
+				    struct sk_buff *skb)
+{
+	return call_int_hook(sctp_assoc_established, 0, asoc, skb);
+}
+EXPORT_SYMBOL(security_sctp_assoc_established);
+
 #endif	/* CONFIG_SECURITY_NETWORK */
 
 #ifdef CONFIG_SECURITY_INFINIBAND