net: ipv6: RTM_GETROUTE: return matched fib result when requested

This patch adds support to return matched fib result when RTM_F_FIB_MATCH
flag is specified in RTM_GETROUTE request. This is useful for user-space
applications/controllers wanting to query a matching route.

Signed-off-by: Roopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 80bda31..2fe84bd 100644 (file)
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -3607,11 +3607,13 @@ static int inet6_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh,
 {
        struct net *net = sock_net(in_skb->sk);
        struct nlattr *tb[RTA_MAX+1];
+       int err, iif = 0, oif = 0;
+       struct dst_entry *dst;
        struct rt6_info *rt;
        struct sk_buff *skb;
        struct rtmsg *rtm;
        struct flowi6 fl6;
-       int err, iif = 0, oif = 0;
+       bool fibmatch;
 
        err = nlmsg_parse(nlh, sizeof(*rtm), tb, RTA_MAX, rtm_ipv6_policy,
                          extack);
@@ -3622,6 +3624,7 @@ static int inet6_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh,
        memset(&fl6, 0, sizeof(fl6));
        rtm = nlmsg_data(nlh);
        fl6.flowlabel = ip6_make_flowinfo(rtm->rtm_tos, 0);
+       fibmatch = !!(rtm->rtm_flags & RTM_F_FIB_MATCH);
 
        if (tb[RTA_SRC]) {
                if (nla_len(tb[RTA_SRC]) < sizeof(struct in6_addr))
@@ -3667,12 +3670,23 @@ static int inet6_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh,
                if (!ipv6_addr_any(&fl6.saddr))
                        flags |= RT6_LOOKUP_F_HAS_SADDR;
 
-               rt = (struct rt6_info *)ip6_route_input_lookup(net, dev, &fl6,
-                                                              flags);
+               if (!fibmatch)
+                       dst = ip6_route_input_lookup(net, dev, &fl6, flags);
        } else {
                fl6.flowi6_oif = oif;
 
-               rt = (struct rt6_info *)ip6_route_output(net, NULL, &fl6);
+               if (!fibmatch)
+                       dst = ip6_route_output(net, NULL, &fl6);
+       }
+
+       if (fibmatch)
+               dst = ip6_route_lookup(net, &fl6, 0);
+
+       rt = container_of(dst, struct rt6_info, dst);
+       if (rt->dst.error) {
+               err = rt->dst.error;
+               ip6_rt_put(rt);
+               goto errout;
        }
 
        if (rt == net->ipv6.ip6_null_entry) {
@@ -3689,10 +3703,14 @@ static int inet6_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh,
        }
 
        skb_dst_set(skb, &rt->dst);
-
-       err = rt6_fill_node(net, skb, rt, &fl6.daddr, &fl6.saddr, iif,
-                           RTM_NEWROUTE, NETLINK_CB(in_skb).portid,
-                           nlh->nlmsg_seq, 0);
+       if (fibmatch)
+               err = rt6_fill_node(net, skb, rt, NULL, NULL, iif,
+                                   RTM_NEWROUTE, NETLINK_CB(in_skb).portid,
+                                   nlh->nlmsg_seq, 0);
+       else
+               err = rt6_fill_node(net, skb, rt, &fl6.daddr, &fl6.saddr, iif,
+                                   RTM_NEWROUTE, NETLINK_CB(in_skb).portid,
+                                   nlh->nlmsg_seq, 0);
        if (err < 0) {
                kfree_skb(skb);
                goto errout;