xfrm: take care of request sockets

TCP SYNACK messages might now be attached to request sockets.

XFRM needs to get back to a listener socket.

Adds new helpers that might be used elsewhere :
sk_to_full_sk() and sk_const_to_full_sk()

Note: We also need to add RCU protection for xfrm lookups,
now TCP/DCCP have lockless listener processing. This will
be addressed in separate patches.

Fixes: ca6fb0651883 ("tcp: attach SYNACK messages to request sockets instead of listener")
Reported-by: Dave Jones <davej@codemonkey.org.uk>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 0 deletions

diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 09bfcbac63bb..18276f0cc32b 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -2198,6 +2198,7 @@ struct dst_entry *xfrm_lookup(struct net *net, struct dst_entry *dst_orig,
         xdst = NULL;
         route = NULL;
 
+        sk = sk_const_to_full_sk(sk);
         if (sk && sk->sk_policy[XFRM_POLICY_OUT]) {
                 num_pols = 1;
                 pols[0] = xfrm_sk_policy_lookup(sk, XFRM_POLICY_OUT, fl);
@@ -2477,6 +2478,7 @@ int __xfrm_policy_check(struct sock *sk, int dir, struct sk_buff *skb,
         }
 
         pol = NULL;
+        sk = sk_to_full_sk(sk);
         if (sk && sk->sk_policy[dir]) {
                 pol = xfrm_sk_policy_lookup(sk, dir, &fl);
                 if (IS_ERR(pol)) {