[PATCH v2] selinux: do not report error on connect(AF_UNSPEC)

[Paolo Abeni <pabeni@redhat.com>]

calling connect(AF_UNSPEC) on an already connected TCP socket is an
established way to disconnect() such socket. After commit 68741a8adab9
("selinux: Fix ltp test connect-syscall failure") it no longer works
and, in the above scenario connect() fails with EAFNOSUPPORT.

Fix the above skipping the checks when the address family is not
AF_INET{4,6} - we don't have any port to validate, but leave the
SCTP code path untouched, as it has specific constraints.

Fixes: 68741a8adab9 ("selinux: Fix ltp test connect-syscall failure")
Reported-by: Tom Deseyn <tdeseyn@redhat.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
---
v1 -> v2:
 - avoid validation for AF_UNSPEC
---
 security/selinux/hooks.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index c61787b15f27..bccc4b3e6f57 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -4674,12 +4674,13 @@ static int selinux_socket_connect_helper(struct socket *sock,
 			break;
 		default:
 			/* Note that SCTP services expect -EINVAL, whereas
-			 * others expect -EAFNOSUPPORT.
+			 * others must handle this at the protocol level:
+			 * connect(AF_UNSPEC) on a connected socket is
+			 * a documented way disconnect the socket
 			 */
 			if (sksec->sclass == SECCLASS_SCTP_SOCKET)
 				return -EINVAL;
-			else
-				return -EAFNOSUPPORT;
+			return 0;
 		}
 
 		err = sel_netport_sid(sk->sk_protocol, snum, &sid);
-- 
2.20.1