[PATCH 2/3] smack: Check address length before reading address family

[Tetsuo Handa]

KMSAN will complain if valid address length passed to bind()/connect()/
sendmsg() is shorter than sizeof("struct sockaddr"->sa_family) bytes.

Also, since smk_ipv6_port_label()/smack_netlabel_send()/
smack_ipv6host_label()/smk_ipv6_check()/smk_ipv6_port_check() are not
checking valid address length and/or address family, make sure we check
both. The minimal valid length in smack_socket_connect() is changed from
sizeof(struct sockaddr_in6) bytes to SIN6_LEN_RFC2133 bytes, for it seems
that Smack is not using "struct sockaddr_in6"->sin6_scope_id field.

Signed-off-by: Tetsuo Handa <penguin-kernel at I-love.SAKURA.ne.jp>
---
 security/smack/smack_lsm.c | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 5c1613519d5a..4b59e4519e0c 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -2805,13 +2805,17 @@ static int smack_socket_socketpair(struct socket *socka,
  *
  * Records the label bound to a port.
  *
- * Returns 0
+ * Returns 0 on success, and error code otherwise
  */
 static int smack_socket_bind(struct socket *sock, struct sockaddr *address,
 				int addrlen)
 {
-	if (sock->sk != NULL && sock->sk->sk_family == PF_INET6)
+	if (sock->sk != NULL && sock->sk->sk_family == PF_INET6) {
+		if (addrlen < SIN6_LEN_RFC2133 ||
+		    address->sa_family != AF_INET6)
+			return -EINVAL;
 		smk_ipv6_port_label(sock, address);
+	}
 	return 0;
 }
 #endif /* SMACK_IPV6_PORT_LABELING */
@@ -2847,12 +2851,13 @@ static int smack_socket_connect(struct socket *sock, struct sockaddr *sap,
 
 	switch (sock->sk->sk_family) {
 	case PF_INET:
-		if (addrlen < sizeof(struct sockaddr_in))
+		if (addrlen < sizeof(struct sockaddr_in) ||
+		    sap->sa_family != AF_INET)
 			return -EINVAL;
 		rc = smack_netlabel_send(sock->sk, (struct sockaddr_in *)sap);
 		break;
 	case PF_INET6:
-		if (addrlen < sizeof(struct sockaddr_in6))
+		if (addrlen < SIN6_LEN_RFC2133 || sap->sa_family != AF_INET6)
 			return -EINVAL;
 #ifdef SMACK_IPV6_SECMARK_LABELING
 		rsp = smack_ipv6host_label(sip);
@@ -3682,9 +3687,15 @@ static int smack_socket_sendmsg(struct socket *sock, struct msghdr *msg,
 
 	switch (sock->sk->sk_family) {
 	case AF_INET:
+		if (msg->msg_namelen < sizeof(struct sockaddr_in) ||
+		    sip->sin_family != AF_INET)
+			return -EINVAL;
 		rc = smack_netlabel_send(sock->sk, sip);
 		break;
 	case AF_INET6:
+		if (msg->msg_namelen < SIN6_LEN_RFC2133 ||
+		    sap->sin6_family != AF_INET6)
+			return -EINVAL;
 #ifdef SMACK_IPV6_SECMARK_LABELING
 		rsp = smack_ipv6host_label(sap);
 		if (rsp != NULL)
-- 
2.16.5