inet: add a redirect generation id in inetpeer

Now inetpeer is the place where we cache redirect information for ipv4
destinations, we must be able to invalidate informations when a route is
added/removed on host.

As inetpeer is not yet namespace aware, this patch adds a shared
redirect_genid, and a per inetpeer redirect_genid. This might be changed
later if inetpeer becomes ns aware.

Cache information for one inerpeer is valid as long as its
redirect_genid has the same value than global redirect_genid.

Reported-by: Arkadiusz Miśkiewicz <a.miskiewicz@gmail.com>
Tested-by: Arkadiusz Miśkiewicz <a.miskiewicz@gmail.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 9 insertions, 1 deletions

diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index fb47c8f0cd86..5c2847247f51 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -131,6 +131,7 @@ static int ip_rt_mtu_expires __read_mostly	= 10 * 60 * HZ;
 static int ip_rt_min_pmtu __read_mostly         = 512 + 20 + 20;
 static int ip_rt_min_advmss __read_mostly       = 256;
 static int rt_chain_length_max __read_mostly    = 20;
+static int redirect_genid;
 
 /*
  *      Interface to generic destination cache.
@@ -837,6 +838,7 @@ static void rt_cache_invalidate(struct net *net)
 
         get_random_bytes(&shuffle, sizeof(shuffle));
         atomic_add(shuffle + 1U, &net->ipv4.rt_genid);
+        redirect_genid++;
 }
 
 /*
@@ -1391,8 +1393,10 @@ void ip_rt_redirect(__be32 old_gw, __be32 daddr, __be32 new_gw,
 
                                 peer = rt->peer;
                                 if (peer) {
-                                        if (peer->redirect_learned.a4 != new_gw) {
+                                        if (peer->redirect_learned.a4 != new_gw ||
+                                            peer->redirect_genid != redirect_genid) {
                                                 peer->redirect_learned.a4 = new_gw;
+                                                peer->redirect_genid = redirect_genid;
                                                 atomic_inc(&__rt_peer_genid);
                                         }
                                         check_peer_redir(&rt->dst, peer);
@@ -1701,6 +1705,8 @@ static struct dst_entry *ipv4_dst_check(struct dst_entry *dst, u32 cookie)
                 if (peer) {
                         check_peer_pmtu(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))
@@ -1857,6 +1863,8 @@ static void rt_init_metrics(struct rtable *rt, const struct flowi4 *fl4,
                 dst_init_metrics(&rt->dst, peer->metrics, false);
 
                 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) {
                         rt->rt_gateway = peer->redirect_learned.a4;