net: Use passed in table for nexthop lookups

If a user passes in a table for new routes use that table for nexthop
lookups. Specifically, this solves the case where a connected route does
not exist in the main table, but only another table and then a subsequent
route is added with a next hop using the connected route. ie.,

$ ip route ls
default via 10.0.2.2 dev eth0
10.0.2.0/24 dev eth0  proto kernel  scope link  src 10.0.2.15
169.254.0.0/16 dev eth0  scope link  metric 1003
192.168.56.0/24 dev eth1  proto kernel  scope link  src 192.168.56.51

$ ip route ls table 10
1.1.1.0/24 dev eth2  scope link

Without this patch adding a nexthop route fails:

$ ip route add table 10 2.2.2.0/24 via 1.1.1.10
RTNETLINK answers: Network is unreachable

With this patch the route is added successfully.

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

diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index 85e9a8abf15c274a4214057e35ebc1835525bed0..b7f1d20a96154b0295ece902def96d637622affe 100644 (file)
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -691,6 +691,7 @@ static int fib_check_nh(struct fib_config *cfg, struct fib_info *fi,
                }
                rcu_read_lock();
                {
+                       struct fib_table *tbl = NULL;
                        struct flowi4 fl4 = {
                                .daddr = nh->nh_gw,
                                .flowi4_scope = cfg->fc_scope + 1,
@@ -701,8 +702,16 @@ static int fib_check_nh(struct fib_config *cfg, struct fib_info *fi,
                        /* It is not necessary, but requires a bit of thinking */
                        if (fl4.flowi4_scope < RT_SCOPE_LINK)
                                fl4.flowi4_scope = RT_SCOPE_LINK;
-                       err = fib_lookup(net, &fl4, &res,
-                                        FIB_LOOKUP_IGNORE_LINKSTATE);
+
+                       if (cfg->fc_table)
+                               tbl = fib_get_table(net, cfg->fc_table);
+
+                       if (tbl)
+                               err = fib_table_lookup(tbl, &fl4, &res,
+                                                  FIB_LOOKUP_IGNORE_LINKSTATE);
+                       else
+                               err = fib_lookup(net, &fl4, &res,
+                                                FIB_LOOKUP_IGNORE_LINKSTATE);
                        if (err) {
                                rcu_read_unlock();
                                return err;