[PATCH net-next 8/8] net: ipv6: RTM_GETROUTE: return matched fib result when requested

[Roopa Prabhu]

From: Roopa Prabhu <ro...@cumulusnetworks.com>

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 <ro...@cumulusnetworks.com>
---
 net/ipv6/route.c | 36 +++++++++++++++++++++++++++++-------
 1 file changed, 29 insertions(+), 7 deletions(-)

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 80bda31..c4d6da9 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -3612,6 +3612,7 @@ static int inet6_rtm_getroute(struct sk_buff *in_skb, 
struct nlmsghdr *nlh,
        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 +3623,7 @@ 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) ? true : false;
 
        if (tb[RTA_SRC]) {
                if (nla_len(tb[RTA_SRC]) < sizeof(struct in6_addr))
@@ -3667,12 +3669,27 @@ 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)
+                       rt = (struct rt6_info *)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)
+                       rt = (struct rt6_info *)ip6_route_output_flags(net,
+                                                                      NULL,
+                                                                      &fl6, 0);
+       }
+
+       if (fibmatch) {
+               rt = (struct rt6_info *)ip6_route_lookup(net, &fl6, 0);
+               if (rt->dst.error) {
+                       err = rt->dst.error;
+                       ip6_rt_put(rt);
+                       goto errout;
+               }
+
        }
 
        if (rt == net->ipv6.ip6_null_entry) {
@@ -3689,10 +3706,15 @@ 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;
-- 
1.9.1