From 3630d40067a21d4dfbadc6002bb469ce26ac5d52 Mon Sep 17 00:00:00 2001 From: Hannes Frederic Sowa Date: Wed, 3 Jul 2013 20:45:04 +0200 Subject: [PATCH] ipv6: rt6_check_neigh should successfully verify neigh if no NUD information are available After the removal of rt->n we do not create a neighbour entry at route insertion time (rt6_bind_neighbour is gone). As long as no neighbour is created because of "useful traffic" we skip this routing entry because rt6_check_neigh cannot pick up a valid neighbour (neigh == NULL) and thus returns false. This change was introduced by commit 887c95cc1da53f66a5890fdeab13414613010097 ("ipv6: Complete neighbour entry removal from dst_entry.") To quote RFC4191: "If the host has no information about the router's reachability, then the host assumes the router is reachable." and also: "A host MUST NOT probe a router's reachability in the absence of useful traffic that the host would have sent to the router if it were reachable." So, just assume the router is reachable and let's rt6_probe do the rest. We don't need to create a neighbour on route insertion time. If we don't compile with CONFIG_IPV6_ROUTER_PREF (RFC4191 support) a neighbour is only valid if its nud_state is NUD_VALID. I did not find any references that we should probe the router on route insertion time via the other RFCs. So skip this route in that case. v2: a) use IS_ENABLED instead of #ifdefs (thanks to Sergei Shtylyov) Reported-by: Pierre Emeriaud Cc: YOSHIFUJI Hideaki Signed-off-by: Hannes Frederic Sowa Signed-off-by: David S. Miller --- net/ipv6/route.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/net/ipv6/route.c b/net/ipv6/route.c index 9ff0b78a9c15..bd5fd7054031 100644 --- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -551,6 +551,8 @@ static inline bool rt6_check_neigh(struct rt6_info *rt) ret = true; #endif read_unlock(&neigh->lock); + } else if (IS_ENABLED(CONFIG_IPV6_ROUTER_PREF)) { + ret = true; } rcu_read_unlock_bh(); -- 2.20.1