tcp: Validate route interface in early demux.

Otherwise we might violate reverse path filtering.

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 9 insertions, 3 deletions

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 13857df1dae1..21e22a00481a 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1676,6 +1676,7 @@ int tcp_v4_early_demux(struct sk_buff *skb)
         struct net *net = dev_net(skb->dev);
         const struct iphdr *iph;
         const struct tcphdr *th;
+        struct net_device *dev;
         struct sock *sk;
         int err;
 
@@ -1695,10 +1696,11 @@ int tcp_v4_early_demux(struct sk_buff *skb)
         if (!pskb_may_pull(skb, ip_hdrlen(skb) + th->doff * 4))
                 goto out_err;
 
+        dev = skb->dev;
         sk = __inet_lookup_established(net, &tcp_hashinfo,
                                        iph->saddr, th->source,
                                        iph->daddr, th->dest,
-                                       skb->dev->ifindex);
+                                       dev->ifindex);
         if (sk) {
                 skb->sk = sk;
                 skb->destructor = sock_edemux;
@@ -1707,8 +1709,12 @@ int tcp_v4_early_demux(struct sk_buff *skb)
                         if (dst)
                                 dst = dst_check(dst, 0);
                         if (dst) {
-                                skb_dst_set_noref(skb, dst);
-                                err = 0;
+                                struct rtable *rt = (struct rtable *) dst;
+
+                                if (rt->rt_iif == dev->ifindex) {
+                                        skb_dst_set_noref(skb, dst);
+                                        err = 0;
+                                }
                         }
                 }
         }