ipv4: Fix "Set rt->rt_iif more sanely on output routes."

Commit 1018b5c01636c7c6bda31a719bda34fc631db29a ("Set rt->rt_iif more
sanely on output routes.")  breaks rt_is_{output,input}_route.

This became the cause to return "IP_PKTINFO's ->ipi_ifindex == 0".

To fix it, this does:

1) Add "int rt_route_iif;" to struct rtable

2) For input routes, always set rt_route_iif to same value as rt_iif

3) For output routes, always set rt_route_iif to zero.  Set rt_iif
   as it is done currently.

4) Change rt_is_{output,input}_route() to test rt_route_iif

Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 2 deletions

diff --git a/include/net/route.h b/include/net/route.h
index f88429cad52a..8fce0621cad1 100644
--- a/include/net/route.h
+++ b/include/net/route.h
@@ -64,6 +64,7 @@ struct rtable {
 
         __be32                  rt_dst; /* Path destination     */
         __be32                  rt_src; /* Path source          */
+        int                     rt_route_iif;
         int                     rt_iif;
         int                     rt_oif;
         __u32                   rt_mark;
@@ -80,12 +81,12 @@ struct rtable {
 
 static inline bool rt_is_input_route(struct rtable *rt)
 {
-        return rt->rt_iif != 0;
+        return rt->rt_route_iif != 0;
 }
 
 static inline bool rt_is_output_route(struct rtable *rt)
 {
-        return rt->rt_iif == 0;
+        return rt->rt_route_iif == 0;
 }
 
 struct ip_rt_acct {