mpls: make via address optional for multipath routes

The via address is optional for a single path route, yet is mandatory
when the multipath attribute is used:

  # ip -f mpls route add 100 dev lo
  # ip -f mpls route add 101 nexthop dev lo
  RTNETLINK answers: Invalid argument

Make them consistent by making the via address optional when the
RTA_MULTIPATH attribute is being parsed so that both forms of
specifying the route work.

Signed-off-by: Robert Shearman <rshearma@brocade.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 13 insertions, 9 deletions

diff --git a/net/mpls/af_mpls.c b/net/mpls/af_mpls.c
index 7bfc85f52ca8..c32fc411a911 100644
--- a/net/mpls/af_mpls.c
+++ b/net/mpls/af_mpls.c
@@ -604,10 +604,14 @@ static int mpls_nh_build(struct net *net, struct mpls_route *rt,
                         goto errout;
         }
 
-        err = nla_get_via(via, &nh->nh_via_alen, &nh->nh_via_table,
-                          __mpls_nh_via(rt, nh));
-        if (err)
-                goto errout;
+        if (via) {
+                err = nla_get_via(via, &nh->nh_via_alen, &nh->nh_via_table,
+                                  __mpls_nh_via(rt, nh));
+                if (err)
+                        goto errout;
+        } else {
+                nh->nh_via_table = MPLS_NEIGH_TABLE_UNSPEC;
+        }
 
         err = mpls_nh_assign_dev(net, rt, nh, oif);
         if (err)
@@ -689,9 +693,6 @@ static int mpls_nh_build_multi(struct mpls_route_config *cfg,
                         nla_newdst = nla_find(attrs, attrlen, RTA_NEWDST);
                 }
 
-                if (!nla_via)
-                        goto errout;
-
                 err = mpls_nh_build(cfg->rc_nlinfo.nl_net, rt, nh,
                                     rtnh->rtnh_ifindex, nla_via,
                                     nla_newdst);
@@ -1271,7 +1272,8 @@ static int mpls_dump_route(struct sk_buff *skb, u32 portid, u32 seq, int event,
                                                             nh->nh_labels,
                                                             nh->nh_label))
                                 goto nla_put_failure;
-                        if (nla_put_via(skb, nh->nh_via_table,
+                        if (nh->nh_via_table != MPLS_NEIGH_TABLE_UNSPEC &&
+                            nla_put_via(skb, nh->nh_via_table,
                                         mpls_nh_via(rt, nh),
                                         nh->nh_via_alen))
                                 goto nla_put_failure;
@@ -1343,7 +1345,9 @@ static inline size_t lfib_nlmsg_size(struct mpls_route *rt)
 
                 for_nexthops(rt) {
                         nhsize += nla_total_size(sizeof(struct rtnexthop));
-                        nhsize += nla_total_size(2 + nh->nh_via_alen);
+                        /* RTA_VIA */
+                        if (nh->nh_via_table != MPLS_NEIGH_TABLE_UNSPEC)
+                                nhsize += nla_total_size(2 + nh->nh_via_alen);
                         if (nh->nh_labels)
                                 nhsize += nla_total_size(nh->nh_labels * 4);
                 } endfor_nexthops(rt);