ipv4: Perform peer validation on cached route lookup.
David S. Miller [Thu, 1 Dec 2011 18:38:59 +0000 (13:38 -0500)]
[ Upstream commit efbc368dcc6426d5430b9b8eeda944cf2cb74b8c,
  incorporating a follow-on change to prevent an OOPS ]

Otherwise we won't notice the peer GENID change.

Reported-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

net/ipv4/route.c

index 65d2572..5c9b20f 100644 (file)
@@ -1311,7 +1311,7 @@ static void rt_del(unsigned hash, struct rtable *rt)
        spin_unlock_bh(rt_hash_lock_addr(hash));
 }
 
-static int check_peer_redir(struct dst_entry *dst, struct inet_peer *peer)
+static void check_peer_redir(struct dst_entry *dst, struct inet_peer *peer)
 {
        struct rtable *rt = (struct rtable *) dst;
        __be32 orig_gw = rt->rt_gateway;
@@ -1322,21 +1322,19 @@ static int check_peer_redir(struct dst_entry *dst, struct inet_peer *peer)
        rt->rt_gateway = peer->redirect_learned.a4;
 
        n = ipv4_neigh_lookup(&rt->dst, &rt->rt_gateway);
-       if (IS_ERR(n))
-               return PTR_ERR(n);
+       if (IS_ERR(n)) {
+               rt->rt_gateway = orig_gw;
+               return;
+       }
        old_n = xchg(&rt->dst._neighbour, n);
        if (old_n)
                neigh_release(old_n);
-       if (!n || !(n->nud_state & NUD_VALID)) {
-               if (n)
-                       neigh_event_send(n, NULL);
-               rt->rt_gateway = orig_gw;
-               return -EAGAIN;
+       if (!(n->nud_state & NUD_VALID)) {
+               neigh_event_send(n, NULL);
        } else {
                rt->rt_flags |= RTCF_REDIRECTED;
                call_netevent_notifiers(NETEVENT_NEIGH_UPDATE, n);
        }
-       return 0;
 }
 
 /* called in rcu_read_lock() section */
@@ -1694,12 +1692,8 @@ static void ip_rt_update_pmtu(struct dst_entry *dst, u32 mtu)
 }
 
 
-static struct dst_entry *ipv4_dst_check(struct dst_entry *dst, u32 cookie)
+static void ipv4_validate_peer(struct rtable *rt)
 {
-       struct rtable *rt = (struct rtable *) dst;
-
-       if (rt_is_expired(rt))
-               return NULL;
        if (rt->rt_peer_genid != rt_peer_genid()) {
                struct inet_peer *peer;
 
@@ -1708,19 +1702,26 @@ static struct dst_entry *ipv4_dst_check(struct dst_entry *dst, u32 cookie)
 
                peer = rt->peer;
                if (peer) {
-                       check_peer_pmtu(dst, peer);
+                       check_peer_pmtu(&rt->dst, peer);
 
                        if (peer->redirect_genid != redirect_genid)
                                peer->redirect_learned.a4 = 0;
                        if (peer->redirect_learned.a4 &&
-                           peer->redirect_learned.a4 != rt->rt_gateway) {
-                               if (check_peer_redir(dst, peer))
-                                       return NULL;
-                       }
+                           peer->redirect_learned.a4 != rt->rt_gateway)
+                               check_peer_redir(&rt->dst, peer);
                }
 
                rt->rt_peer_genid = rt_peer_genid();
        }
+}
+
+static struct dst_entry *ipv4_dst_check(struct dst_entry *dst, u32 cookie)
+{
+       struct rtable *rt = (struct rtable *) dst;
+
+       if (rt_is_expired(rt))
+               return NULL;
+       ipv4_validate_peer(rt);
        return dst;
 }
 
@@ -2370,6 +2371,7 @@ int ip_route_input_common(struct sk_buff *skb, __be32 daddr, __be32 saddr,
                    rth->rt_mark == skb->mark &&
                    net_eq(dev_net(rth->dst.dev), net) &&
                    !rt_is_expired(rth)) {
+                       ipv4_validate_peer(rth);
                        if (noref) {
                                dst_use_noref(&rth->dst, jiffies);
                                skb_dst_set_noref(skb, &rth->dst);
@@ -2745,6 +2747,7 @@ struct rtable *__ip_route_output_key(struct net *net, struct flowi4 *flp4)
                            (IPTOS_RT_MASK | RTO_ONLINK)) &&
                    net_eq(dev_net(rth->dst.dev), net) &&
                    !rt_is_expired(rth)) {
+                       ipv4_validate_peer(rth);
                        dst_use(&rth->dst, jiffies);
                        RT_CACHE_STAT_INC(out_hit);
                        rcu_read_unlock_bh();