xfrm: choose protocol family by skb protocol

We need to choose the protocol family by skb->protocol. Otherwise we
call the wrong xfrm{4,6}_local_error handler in case an ipv6 sockets is
used in ipv4 mode, in which case we should call down to xfrm4_local_error
(ip6 sockets are a superset of ip4 ones).

We are called before before ip_output functions, so skb->protocol is
not reset.

Cc: Steffen Klassert <steffen.klassert@secunet.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

1 files changed, 9 insertions, 1 deletions

diff --git a/net/xfrm/xfrm_output.c b/net/xfrm/xfrm_output.c
index 6f5fc612b162..3bb2cdc13b46 100644
--- a/net/xfrm/xfrm_output.c
+++ b/net/xfrm/xfrm_output.c
@@ -216,9 +216,17 @@ int xfrm_inner_extract_output(struct xfrm_state *x, struct sk_buff *skb)
 
 void xfrm_local_error(struct sk_buff *skb, int mtu)
 {
+        unsigned int proto;
         struct xfrm_state_afinfo *afinfo;
 
-        afinfo = xfrm_state_get_afinfo(skb->sk->sk_family);
+        if (skb->protocol == htons(ETH_P_IP))
+                proto = AF_INET;
+        else if (skb->protocol == htons(ETH_P_IPV6))
+                proto = AF_INET6;
+        else
+                return;
+
+        afinfo = xfrm_state_get_afinfo(proto);
         if (!afinfo)
                 return;