[PATCH RFC 1/3] ipv6: Fix after pmtu events dissapearing host routes

[Steffen Klassert <steffen.klassert@secunet.com>]

We currently don't clone host routes before we use them.
If a pmtu event is received on such a route, it gets
an expires value. As soon as the expiration time is
elapsed, the route is deleted. As a result, the host
es not reachable any more.

We fix this by cloning host routes if they are not local,
i.e. if pmtu events can happen. Also adjust the route
deletion because the cached and the original host route
are on the same fib node.

Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
---
 net/ipv6/route.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 4688bd4..4318626 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -961,7 +961,7 @@ redo_rt6_select:
 
 	if (!(rt->rt6i_flags & (RTF_NONEXTHOP | RTF_GATEWAY)))
 		nrt = rt6_alloc_cow(rt, &fl6->daddr, &fl6->saddr);
-	else if (!(rt->dst.flags & DST_HOST))
+	else if (!(rt->dst.flags & DST_HOST) || !(rt->rt6i_flags & RTF_LOCAL))
 		nrt = rt6_alloc_clone(rt, &fl6->daddr);
 	else
 		goto out2;
@@ -1796,6 +1796,8 @@ static int ip6_route_del(struct fib6_config *cfg)
 				continue;
 			if (cfg->fc_metric && cfg->fc_metric != rt->rt6i_metric)
 				continue;
+			if (!(cfg->fc_flags & RTF_CACHE) && (rt->rt6i_flags & RTF_CACHE))
+				continue;
 			dst_hold(&rt->dst);
 			read_unlock_bh(&table->tb6_lock);
 
@@ -2433,6 +2435,9 @@ static int rtm_to_fib6_config(struct sk_buff *skb, struct nlmsghdr *nlh,
 	if (rtm->rtm_type == RTN_LOCAL)
 		cfg->fc_flags |= RTF_LOCAL;
 
+	if (rtm->rtm_flags & RTM_F_CLONED)
+		cfg->fc_flags |= RTF_CACHE;
+
 	cfg->fc_nlinfo.portid = NETLINK_CB(skb).portid;
 	cfg->fc_nlinfo.nlh = nlh;
 	cfg->fc_nlinfo.nl_net = sock_net(skb->sk);
-- 
1.9.1