ipv4: Invalidate nexthop cache nh_saddr more correctly.

Any operation that:

1) Brings up an interface
2) Adds an IP address to an interface
3) Deletes an IP address from an interface

can potentially invalidate the nh_saddr value, requiring
it to be recomputed.

Perform the recomputation lazily using a generation ID.

Reported-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 4 insertions, 2 deletions

diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 34921b0d3f8e..4b0c81180804 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -1718,7 +1718,7 @@ void ip_rt_get_source(u8 *addr, struct rtable *rt)
 
                 rcu_read_lock();
                 if (fib_lookup(dev_net(rt->dst.dev), &fl4, &res) == 0)
-                        src = FIB_RES_PREFSRC(res);
+                        src = FIB_RES_PREFSRC(dev_net(rt->dst.dev), res);
                 else
                         src = inet_select_addr(rt->dst.dev, rt->rt_gateway,
                                         RT_SCOPE_UNIVERSE);
@@ -2615,7 +2615,7 @@ static struct rtable *ip_route_output_slow(struct net *net,
                 fib_select_default(&res);
 
         if (!fl4.saddr)
-                fl4.saddr = FIB_RES_PREFSRC(res);
+                fl4.saddr = FIB_RES_PREFSRC(net, res);
 
         dev_out = FIB_RES_DEV(res);
         fl4.flowi4_oif = dev_out->ifindex;
@@ -3219,6 +3219,8 @@ static __net_init int rt_genid_init(struct net *net)
 {
         get_random_bytes(&net->ipv4.rt_genid,
                          sizeof(net->ipv4.rt_genid));
+        get_random_bytes(&net->ipv4.dev_addr_genid,
+                         sizeof(net->ipv4.dev_addr_genid));
         return 0;
 }