ipv6: expose RFC4191 route preference via rtnetlink

This makes it possible to retain the route preference when RAs are handled in
userspace.

Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
Reviewed-by: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 15 insertions, 1 deletions

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 06fa819c43c9..58c0e6a4d15d 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -2398,6 +2398,7 @@ static const struct nla_policy rtm_ipv6_policy[RTA_MAX+1] = {
         [RTA_PRIORITY]          = { .type = NLA_U32 },
         [RTA_METRICS]           = { .type = NLA_NESTED },
         [RTA_MULTIPATH]         = { .len = sizeof(struct rtnexthop) },
+        [RTA_PREF]              = { .type = NLA_U8 },
 };
 
 static int rtm_to_fib6_config(struct sk_buff *skb, struct nlmsghdr *nlh,
@@ -2405,6 +2406,7 @@ static int rtm_to_fib6_config(struct sk_buff *skb, struct nlmsghdr *nlh,
 {
         struct rtmsg *rtm;
         struct nlattr *tb[RTA_MAX+1];
+        unsigned int pref;
         int err;
 
         err = nlmsg_parse(nlh, sizeof(*rtm), tb, RTA_MAX, rtm_ipv6_policy);
@@ -2480,6 +2482,14 @@ static int rtm_to_fib6_config(struct sk_buff *skb, struct nlmsghdr *nlh,
                 cfg->fc_mp_len = nla_len(tb[RTA_MULTIPATH]);
         }
 
+        if (tb[RTA_PREF]) {
+                pref = nla_get_u8(tb[RTA_PREF]);
+                if (pref != ICMPV6_ROUTER_PREF_LOW &&
+                    pref != ICMPV6_ROUTER_PREF_HIGH)
+                        pref = ICMPV6_ROUTER_PREF_MEDIUM;
+                cfg->fc_flags |= RTF_PREF(pref);
+        }
+
         err = 0;
 errout:
         return err;
@@ -2583,7 +2593,8 @@ static inline size_t rt6_nlmsg_size(void)
                + nla_total_size(4) /* RTA_PRIORITY */
                + RTAX_MAX * nla_total_size(4) /* RTA_METRICS */
                + nla_total_size(sizeof(struct rta_cacheinfo))
-               + nla_total_size(TCP_CA_NAME_MAX); /* RTAX_CC_ALGO */
+               + nla_total_size(TCP_CA_NAME_MAX) /* RTAX_CC_ALGO */
+               + nla_total_size(1); /* RTA_PREF */
 }
 
 static int rt6_fill_node(struct net *net,
@@ -2724,6 +2735,9 @@ static int rt6_fill_node(struct net *net,
         if (rtnl_put_cacheinfo(skb, &rt->dst, 0, expires, rt->dst.error) < 0)
                 goto nla_put_failure;
 
+        if (nla_put_u8(skb, RTA_PREF, IPV6_EXTRACT_PREF(rt->rt6i_flags)))
+                goto nla_put_failure;
+
         nlmsg_end(skb, nlh);
         return 0;