[PATCH net] ipv6: allows gracefull fallback from table lookup

[PATCH net] ipv6: allows gracefull fallback from table lookup

[Paolo Abeni]

with the commit 8c14586fc320 ("net: ipv6: Use passed in table for
nexthop lookups"), net hop lookup is first performed on route creation
in the passed-in table.
However device match is not enforced in table lookup, so the found
route can be later discarded due to egress device mismatch and no
global lookup will be performed.
This cause the following to fail:

ip link add dummy1 type dummy
ip link add dummy2 type dummy
ip link set dummy1 up
ip link set dummy2 up
ip route add 2001:db8:8086::/48 dev dummy1 metric 20
ip route add 2001:db8:d34d::/64 via 2001:db8:8086::2 dev dummy1 metric 20
ip route add 2001:db8:8086::/48 dev dummy2 metric 21
ip route add 2001:db8:d34d::/64 via 2001:db8:8086::2 dev dummy2 metric 21
RTNETLINK answers: No route to host

This change fixes the issue enforcing device lookup in
ip6_nh_lookup_table()

Fixes: 8c14586fc320 ("net: ipv6: Use passed in table for nexthop lookups")
Reported-and-tested-by: Beniamino Galvani <bgalvani@redhat.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
---
 net/ipv6/route.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 969913d..520b788 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -1782,7 +1782,7 @@ static struct rt6_info *ip6_nh_lookup_table(struct net *net,
 	};
 	struct fib6_table *table;
 	struct rt6_info *rt;
-	int flags = 0;
+	int flags = RT6_LOOKUP_F_IFACE;
 
 	table = fib6_get_table(net, cfg->fc_table);
 	if (!table)
-- 
1.8.3.1

Re: [PATCH net] ipv6: allows gracefull fallback from table lookup

[Paolo Abeni]

On Thu, 2016-06-23 at 15:11 +0200, Paolo Abeni wrote:
> with the commit 8c14586fc320 ("net: ipv6: Use passed in table for
> nexthop lookups"), net hop lookup is first performed on route creation
> in the passed-in table.
> However device match is not enforced in table lookup, so the found
> route can be later discarded due to egress device mismatch and no
> global lookup will be performed.
> This cause the following to fail:
> 
> ip link add dummy1 type dummy
> ip link add dummy2 type dummy
> ip link set dummy1 up
> ip link set dummy2 up
> ip route add 2001:db8:8086::/48 dev dummy1 metric 20
> ip route add 2001:db8:d34d::/64 via 2001:db8:8086::2 dev dummy1 metric 20
> ip route add 2001:db8:8086::/48 dev dummy2 metric 21
> ip route add 2001:db8:d34d::/64 via 2001:db8:8086::2 dev dummy2 metric 21
> RTNETLINK answers: No route to host
> 
> This change fixes the issue enforcing device lookup in
> ip6_nh_lookup_table()
> 
> Fixes: 8c14586fc320 ("net: ipv6: Use passed in table for nexthop lookups")
> Reported-and-tested-by: Beniamino Galvani <bgalvani@redhat.com>
> Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Oops, bad commit message title (not updated from a previous
implementation), I'll resubmit with a more relevant one. Sorry for the
noise.

Paolo