From: Tom Herbert <tom@quantonium.net>
Date: Wed, 24 Jan 2018 20:35:40 +0000 (-0800)
Subject: kcm: Only allow TCP sockets to be attached to a KCM mux
X-Git-Tag: C0P2-H0.0--20200415~5195
X-Git-Url: https://git.somdevices.com/?a=commitdiff_plain;h=2bb174afca6cdb90499bcd2c46e5d966d9976834;p=linux.git

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

commit 581e7226a5d43f629eb6399a121f85f6a15f81be upstream.

TCP sockets for IPv4 and IPv6 that are not listeners or in closed
stated are allowed to be attached to a KCM mux.

Fixes: ab7ac4eb9832 ("kcm: Kernel Connection Multiplexor module")
Reported-by: syzbot+8865eaff7f9acd593945@syzkaller.appspotmail.com
Signed-off-by: Tom Herbert <tom@quantonium.net>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/net/kcm/kcmsock.c b/net/kcm/kcmsock.c
index 69bef8ee04b4..179cd9b1b1f4 100644
--- a/net/kcm/kcmsock.c
+++ b/net/kcm/kcmsock.c
@@ -1381,8 +1381,13 @@ 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);