path: root/net/ipv6/route.c
diff options
authorStefano Brivio <sbrivio@redhat.com>2019-09-09 22:44:06 +0200
committerDavid S. Miller <davem@davemloft.net>2019-09-11 23:52:17 +0100
commitcbfd68913c5d260260e56bcef8b3c4a449751795 (patch)
treeb7a2aa2f20dacbaf34959687c15f1bb193b5fd95 /net/ipv6/route.c
parentnet: stmmac: pci: Add HAPS support using GMAC5 (diff)
ipv6: Don't use dst gateway directly in ip6_confirm_neigh()
This is the equivalent of commit 2c6b55f45d53 ("ipv6: fix neighbour resolution with raw socket") for ip6_confirm_neigh(): we can send a packet with MSG_CONFIRM on a raw socket for a connected route, so the gateway would be :: here, and we should pick the next hop using rt6_nexthop() instead. This was found by code review and, to the best of my knowledge, doesn't actually fix a practical issue: the destination address from the packet is not considered while confirming a neighbour, as ip6_confirm_neigh() calls choose_neigh_daddr() without passing the packet, so there are no similar issues as the one fixed by said commit. A possible source of issues with the existing implementation might come from the fact that, if we have a cached dst, we won't consider it, while rt6_nexthop() takes care of that. I might just not be creative enough to find a practical problem here: the only way to affect this with cached routes is to have one coming from an ICMPv6 redirect, but if the next hop is a directly connected host, there should be no topology for which a redirect applies here, and tests with redirected routes show no differences for MSG_CONFIRM (and MSG_PROBE) packets on raw sockets destined to a directly connected host. However, directly using the dst gateway here is not consistent anymore with neighbour resolution, and, in general, as we want the next hop, using rt6_nexthop() looks like the only sane way to fetch it. Reported-by: Guillaume Nault <gnault@redhat.com> Signed-off-by: Stefano Brivio <sbrivio@redhat.com> Acked-by: Guillaume Nault <gnault@redhat.com> Acked-by: Nicolas Dichtel <nicolas.dichtel@6wind.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv6/route.c')
1 files changed, 1 insertions, 1 deletions
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 7a5d331cdefa..874641d4d2a1 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -227,7 +227,7 @@ static void ip6_confirm_neigh(const struct dst_entry *dst, const void *daddr)
struct net_device *dev = dst->dev;
struct rt6_info *rt = (struct rt6_info *)dst;
- daddr = choose_neigh_daddr(&rt->rt6i_gateway, NULL, daddr);
+ daddr = choose_neigh_daddr(rt6_nexthop(rt, &in6addr_any), NULL, daddr);
if (!daddr)
if (dev->flags & (IFF_NOARP | IFF_LOOPBACK))