net: ipv6: Use passed in table for nexthop lookups

Similar to 3bfd847203c6 ("net: Use passed in table for nexthop lookups")
for IPv4, if the route spec contains a table id use that to lookup the
next hop first and fall back to a full lookup if it fails (per the fix
4c9bcd117918b ("net: Fix nexthop lookups")).

Example:

    root@kenny:~# ip -6 ro ls table red
    local 2100:1::1 dev lo  proto none  metric 0  pref medium
    2100:1::/120 dev eth1  proto kernel  metric 256  pref medium
    local 2100:2::1 dev lo  proto none  metric 0  pref medium
    2100:2::/120 dev eth2  proto kernel  metric 256  pref medium
    local fe80::e0:f9ff:fe09:3cac dev lo  proto none  metric 0  pref medium
    local fe80::e0:f9ff:fe1c:b974 dev lo  proto none  metric 0  pref medium
    fe80::/64 dev eth1  proto kernel  metric 256  pref medium
    fe80::/64 dev eth2  proto kernel  metric 256  pref medium
    ff00::/8 dev red  metric 256  pref medium
    ff00::/8 dev eth1  metric 256  pref medium
    ff00::/8 dev eth2  metric 256  pref medium
    unreachable default dev lo  metric 240  error -113 pref medium

    root@kenny:~# ip -6 ro add table red 2100:3::/64 via 2100:1::64
    RTNETLINK answers: No route to host

Route add fails even though 2100:1::64 is a reachable next hop:
    root@kenny:~# ping6 -I red  2100:1::64
    ping6: Warning: source address might be selected on device other than red.
    PING 2100:1::64(2100:1::64) from 2100:1::1 red: 56 data bytes
    64 bytes from 2100:1::64: icmp_seq=1 ttl=64 time=1.33 ms

With this patch:
    root@kenny:~# ip -6 ro add table red 2100:3::/64 via 2100:1::64
    root@kenny:~# ip -6 ro ls table red
    local 2100:1::1 dev lo  proto none  metric 0  pref medium
    2100:1::/120 dev eth1  proto kernel  metric 256  pref medium
    local 2100:2::1 dev lo  proto none  metric 0  pref medium
    2100:2::/120 dev eth2  proto kernel  metric 256  pref medium
    2100:3::/64 via 2100:1::64 dev eth1  metric 1024  pref medium
    local fe80::e0:f9ff:fe09:3cac dev lo  proto none  metric 0  pref medium
    local fe80::e0:f9ff:fe1c:b974 dev lo  proto none  metric 0  pref medium
    fe80::/64 dev eth1  proto kernel  metric 256  pref medium
    fe80::/64 dev eth2  proto kernel  metric 256  pref medium
    ff00::/8 dev red  metric 256  pref medium
    ff00::/8 dev eth1  metric 256  pref medium
    ff00::/8 dev eth2  metric 256  pref medium
    unreachable default dev lo  metric 240  error -113 pref medium

Signed-off-by: David Ahern <dsa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index d916d6ab9ad29aeaeb4bfc57276549f3ae839f40..af46e19205f52319bfba5a9706549567d4447992 100644 (file)
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -1769,6 +1769,37 @@ static int ip6_convert_metrics(struct mx6_config *mxc,
        return -EINVAL;
 }
 
+static struct rt6_info *ip6_nh_lookup_table(struct net *net,
+                                           struct fib6_config *cfg,
+                                           const struct in6_addr *gw_addr)
+{
+       struct flowi6 fl6 = {
+               .flowi6_oif = cfg->fc_ifindex,
+               .daddr = *gw_addr,
+               .saddr = cfg->fc_prefsrc,
+       };
+       struct fib6_table *table;
+       struct rt6_info *rt;
+       int flags = 0;
+
+       table = fib6_get_table(net, cfg->fc_table);
+       if (!table)
+               return NULL;
+
+       if (!ipv6_addr_any(&cfg->fc_prefsrc))
+               flags |= RT6_LOOKUP_F_HAS_SADDR;
+
+       rt = ip6_pol_route(net, table, cfg->fc_ifindex, &fl6, flags);
+
+       /* if table lookup failed, fall back to full lookup */
+       if (rt == net->ipv6.ip6_null_entry) {
+               ip6_rt_put(rt);
+               rt = NULL;
+       }
+
+       return rt;
+}
+
 static struct rt6_info *ip6_route_info_create(struct fib6_config *cfg)
 {
        struct net *net = cfg->fc_nlinfo.nl_net;
@@ -1940,7 +1971,7 @@ static struct rt6_info *ip6_route_info_create(struct fib6_config *cfg)
                rt->rt6i_gateway = *gw_addr;
 
                if (gwa_type != (IPV6_ADDR_LINKLOCAL|IPV6_ADDR_UNICAST)) {
-                       struct rt6_info *grt;
+                       struct rt6_info *grt = NULL;
 
                        /* IPv6 strictly inhibits using not link-local
                           addresses as nexthop address.
@@ -1952,7 +1983,12 @@ static struct rt6_info *ip6_route_info_create(struct fib6_config *cfg)
                        if (!(gwa_type & IPV6_ADDR_UNICAST))
                                goto out;
 
-                       grt = rt6_lookup(net, gw_addr, NULL, cfg->fc_ifindex, 1);
+                       if (cfg->fc_table)
+                               grt = ip6_nh_lookup_table(net, cfg, gw_addr);
+
+                       if (!grt)
+                               grt = rt6_lookup(net, gw_addr, NULL,
+                                                cfg->fc_ifindex, 1);
 
                        err = -EHOSTUNREACH;
                        if (!grt)