linux-kernel - [ 36/73] route: fix ICMP redirect validation

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Date:	Mon, 27 Feb 2012 17:02:39 -0800
From:	Greg KH <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	alan@...rguk.ukuu.org.uk, Flavio Leitner <fbl@...hat.com>,
	"David S. Miller" <davem@...emloft.net>
Subject: [ 36/73] route: fix ICMP redirect validation

3.0-stable review patch.  If anyone has any objections, please let me know.

------------------


From: Flavio Leitner <fbl@...hat.com>

[ Upstream commit 7cc9150ebe8ec06cafea9f1c10d92ddacf88d8ae ]

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 <fbl@...hat.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/ipv4/route.c |   40 +++++++++++++++++++++++++++++++++-------
 1 file changed, 33 insertions(+), 7 deletions(-)

--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -1373,7 +1373,12 @@ static void rt_del(unsigned hash, struct
 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;
 
@@ -1396,13 +1401,34 @@ void ip_rt_redirect(__be32 old_gw, __be3
 			goto reject_redirect;
 	}
 
-	peer = inet_getpeer_v4(daddr, 1);
-	if (peer) {
-		peer->redirect_learned.a4 = new_gw;
-
-		inet_putpeer(peer);
-
-		atomic_inc(&__rt_peer_genid);
+	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;
+
+			if (rt->dst.error || rt->dst.dev != dev ||
+			    rt->rt_gateway != old_gw) {
+				ip_rt_put(rt);
+				continue;
+			}
+
+			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;
 


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