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>

2 files changed, 11 insertions, 2 deletions

diff --git a/include/net/ip_fib.h b/include/net/ip_fib.h
index a1a858035913..cd92b923a578 100644
--- a/include/net/ip_fib.h
+++ b/include/net/ip_fib.h
@@ -62,6 +62,7 @@ struct fib_nh {
         int                     nh_oif;
         __be32                  nh_gw;
         __be32                  nh_saddr;
+        int                     nh_saddr_genid;
 };
 
 /*
@@ -141,12 +142,19 @@ struct fib_result_nl {
 
 #endif /* CONFIG_IP_ROUTE_MULTIPATH */
 
-#define FIB_RES_SADDR(res)              (FIB_RES_NH(res).nh_saddr)
+extern __be32 fib_info_update_nh_saddr(struct net *net, struct fib_nh *nh);
+
+#define FIB_RES_SADDR(net, res)                         \
+        ((FIB_RES_NH(res).nh_saddr_genid ==             \
+          atomic_read(&(net)->ipv4.dev_addr_genid)) ?   \
+         FIB_RES_NH(res).nh_saddr :                     \
+         fib_info_update_nh_saddr((net), &FIB_RES_NH(res)))
 #define FIB_RES_GW(res)                 (FIB_RES_NH(res).nh_gw)
 #define FIB_RES_DEV(res)                (FIB_RES_NH(res).nh_dev)
 #define FIB_RES_OIF(res)                (FIB_RES_NH(res).nh_oif)
 
-#define FIB_RES_PREFSRC(res)            ((res).fi->fib_prefsrc ? : FIB_RES_SADDR(res))
+#define FIB_RES_PREFSRC(net, res)       ((res).fi->fib_prefsrc ? : \
+                                         FIB_RES_SADDR(net, res))
 
 struct fib_table {
         struct hlist_node tb_hlist;
diff --git a/include/net/netns/ipv4.h b/include/net/netns/ipv4.h
index e2e2ef57eca2..542195d9469e 100644
--- a/include/net/netns/ipv4.h
+++ b/include/net/netns/ipv4.h
@@ -55,6 +55,7 @@ struct netns_ipv4 {
         int current_rt_cache_rebuild_count;
 
         atomic_t rt_genid;
+        atomic_t dev_addr_genid;
 
 #ifdef CONFIG_IP_MROUTE
 #ifndef CONFIG_IP_MROUTE_MULTIPLE_TABLES