kcm: Only allow TCP sockets to be attached to a KCM mux

TCP sockets for IPv4 and IPv6 that are not listeners or in closed stated are allowed to be attached to a KCM mux. Fixes: ab7ac4e ("kcm: Kernel Connection Multiplexor module") Reported-by: [email protected] Signed-off-by: Tom Herbert <[email protected]> Reviewed-by: Eric Dumazet <[email protected]> Signed-off-by: David S. Miller <[email protected]>
chewitt · Jan 24, 2018 · 581e722 · 581e722
1 parent d3303a6
commit 581e722
Showing 1 changed file with 7 additions and 2 deletions.
diff --git a/net/kcm/kcmsock.c b/net/kcm/kcmsock.c
@@ -1387,8 +1387,13 @@ static int kcm_attach(struct socket *sock, struct socket *csock,
 	if (!csk)
 		return -EINVAL;
 
-	/* We must prevent loops or risk deadlock ! */
-	if (csk->sk_family == PF_KCM)
+	/* Only allow TCP sockets to be attached for now */
+	if ((csk->sk_family != AF_INET && csk->sk_family != AF_INET6) ||
+	    csk->sk_protocol != IPPROTO_TCP)
+		return -EOPNOTSUPP;
+
+	/* Don't allow listeners or closed sockets */
+	if (csk->sk_state == TCP_LISTEN || csk->sk_state == TCP_CLOSE)
 		return -EOPNOTSUPP;
 
 	psock = kmem_cache_zalloc(kcm_psockp, GFP_KERNEL);