[PATCH] tcp: assign the sock correctly to an outgoing SYNACK packet

[Paul Moore <pmoore@redhat.com>]

Commit 90ba9b1986b5ac4b2d184575847147ea7c4280a2 converted
tcp_make_synack() to use alloc_skb() directly instead of calling
sock_wmalloc(), the goal being the elimination of two atomic
operations.  Unfortunately, in doing so the change broke certain
SELinux/NetLabel configurations by no longer correctly assigning
the sock to the outgoing packet.

This patch fixes this regression by doing the skb->sk assignment
directly inside tcp_make_synack().

Reported-by: Miroslav Vadkerti <mvadkert@redhat.com>
Signed-off-by: Paul Moore <pmoore@redhat.com>
---
 net/ipv4/tcp_output.c |    2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 5d0b438..23cc295 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -2705,6 +2705,8 @@ struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst,
 		dst_release(dst);
 		return NULL;
 	}
+	skb->sk = sk;
+
 	/* Reserve space for headers. */
 	skb_reserve(skb, MAX_TCP_HEADER);