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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@redhat.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@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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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