[19/88] ipv4: fix redirect handling for TCP packets

From: Steven Rostedt
Date: Tue Aug 13 2013 - 12:08:03 EST stable review patch.
If anyone has any objections, please let me know.


From: Michal Kubecek <mkubecek@xxxxxxx>

[ Upstream commit f96ef988cc603487c03a6de07807b06cbe641829 ]

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@xxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
net/ipv4/route.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 39de0ca..59781e0 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -741,10 +741,15 @@ 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);


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