From 7cc9150ebe8ec06cafea9f1c10d92ddacf88d8ae Mon Sep 17 00:00:00 2001 From: Flavio Leitner Date: Mon, 24 Oct 2011 02:56:38 -0400 Subject: [PATCH] route: fix ICMP redirect validation The commit f39925dbde7788cfb96419c0f092b086aa325c0f (ipv4: Cache learned redirect information in inetpeer.) removed some ICMP packet validations which are required by RFC 1122, section 3.2.2.2: ... A Redirect message SHOULD be silently discarded if the new gateway address it specifies is not on the same connected (sub-) net through which the Redirect arrived [INTRO:2, Appendix A], or if the source of the Redirect is not the current first-hop gateway for the specified destination (see Section 3.3.1). Signed-off-by: Flavio Leitner Signed-off-by: David S. Miller --- net/ipv4/route.c | 36 +++++++++++++++++++++++++++++++----- 1 file changed, 31 insertions(+), 5 deletions(-) diff --git a/net/ipv4/route.c b/net/ipv4/route.c index 075212e..41557e2 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -1309,7 +1309,12 @@ static void rt_del(unsigned hash, struct rtable *rt) void ip_rt_redirect(__be32 old_gw, __be32 daddr, __be32 new_gw, __be32 saddr, struct net_device *dev) { + int s, i; struct in_device *in_dev = __in_dev_get_rcu(dev); + struct rtable *rt; + __be32 skeys[2] = { saddr, 0 }; + int ikeys[2] = { dev->ifindex, 0 }; + struct flowi4 fl4; struct inet_peer *peer; struct net *net; @@ -1332,13 +1337,34 @@ void ip_rt_redirect(__be32 old_gw, __be32 daddr, __be32 new_gw, goto reject_redirect; } - peer = inet_getpeer_v4(daddr, 1); - if (peer) { - peer->redirect_learned.a4 = new_gw; + memset(&fl4, 0, sizeof(fl4)); + fl4.daddr = daddr; + for (s = 0; s < 2; s++) { + for (i = 0; i < 2; i++) { + fl4.flowi4_oif = ikeys[i]; + fl4.saddr = skeys[s]; + rt = __ip_route_output_key(net, &fl4); + if (IS_ERR(rt)) + continue; - inet_putpeer(peer); + if (rt->dst.error || rt->dst.dev != dev || + rt->rt_gateway != old_gw) { + ip_rt_put(rt); + continue; + } - atomic_inc(&__rt_peer_genid); + if (!rt->peer) + rt_bind_peer(rt, rt->rt_dst, 1); + + peer = rt->peer; + if (peer) { + peer->redirect_learned.a4 = new_gw; + atomic_inc(&__rt_peer_genid); + } + + ip_rt_put(rt); + return; + } } return; -- 2.7.4