ipv4: Fix reverse path filtering with multipath routing.

Actually iterate over the next-hops to make sure we have
a device match.  Otherwise RP filtering is always elided
when the route matched has multiple next-hops.

Reported-by: Igor M Podlesny <for.poige@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 13 insertions, 2 deletions

diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index a43968918350..7d02a9f999fa 100644
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -246,6 +246,7 @@ int fib_validate_source(__be32 src, __be32 dst, u8 tos, int oif,
 
         struct fib_result res;
         int no_addr, rpf, accept_local;
+        bool dev_match;
         int ret;
         struct net *net;
 
@@ -273,12 +274,22 @@ int fib_validate_source(__be32 src, __be32 dst, u8 tos, int oif,
         }
         *spec_dst = FIB_RES_PREFSRC(res);
         fib_combine_itag(itag, &res);
+        dev_match = false;
+
 #ifdef CONFIG_IP_ROUTE_MULTIPATH
-        if (FIB_RES_DEV(res) == dev || res.fi->fib_nhs > 1)
+        for (ret = 0; ret < res.fi->fib_nhs; ret++) {
+                struct fib_nh *nh = &res.fi->fib_nh[ret];
+
+                if (nh->nh_dev == dev) {
+                        dev_match = true;
+                        break;
+                }
+        }
 #else
         if (FIB_RES_DEV(res) == dev)
+                dev_match = true;
 #endif
-        {
+        if (dev_match) {
                 ret = FIB_RES_NH(res).nh_scope >= RT_SCOPE_HOST;
                 fib_res_put(&res);
                 return ret;