ipv4: fix redirect handling for TCP packets

Unlike ipv4_redirect() and ipv4_sk_redirect(), ip_do_redirect()
doesn't call __build_flow_key() directly but via
ip_rt_build_flow_key() wrapper. This leads to __build_flow_key()
getting pointer to IPv4 header of the ICMP redirect packet
rather than pointer to the embedded IPv4 header of the packet
initiating the redirect.

As a result, handling of ICMP redirects initiated by TCP packets
is broken. Issue was introduced by

	4895c771c ("ipv4: Add FIB nexthop exceptions.")

Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 6 insertions, 1 deletions

diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 550781a17b34..d35bbf0cf404 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -737,10 +737,15 @@ static void ip_do_redirect(struct dst_entry *dst, struct sock *sk, struct sk_buf
 {
         struct rtable *rt;
         struct flowi4 fl4;
+        const struct iphdr *iph = (const struct iphdr *) skb->data;
+        int oif = skb->dev->ifindex;
+        u8 tos = RT_TOS(iph->tos);
+        u8 prot = iph->protocol;
+        u32 mark = skb->mark;
 
         rt = (struct rtable *) dst;
 
-        ip_rt_build_flow_key(&fl4, sk, skb);
+        __build_flow_key(&fl4, sk, iph, oif, tos, prot, mark, 0);
         __ip_do_redirect(rt, skb, &fl4, true);
 }