ipv6:introduce function to find route for redirect
RFC 4861 says that the IP source address of the Redirect is the
same as the current first-hop router for the specified ICMP
Destination Address, so the gateway should be taken into
consideration when we find the route for redirect.
There was once a check in commit
a6279458c534d01ccc39498aba61c93083ee0372 ("NDISC: Search over
all possible rules on receipt of redirect.") and the check
went away in commit b94f1c0904da9b8bf031667afc48080ba7c3e8c9
("ipv6: Use icmpv6_notify() to propagate redirect, instead of
rt6_redirect()").
The bug is only "exploitable" on layer-2 because the source
address of the redirect is checked to be a valid link-local
address but it makes spoofing a lot easier in the same L2
domain nonetheless.
Thanks very much for Hannes's help.
Signed-off-by: Duan Jiong <duanj.fnst@cn.fujitsu.com>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c
index 2221065..c4bc7a3 100644
--- a/net/ipv6/ndisc.c
+++ b/net/ipv6/ndisc.c
@@ -1367,7 +1367,8 @@
return;
if (!ndopts.nd_opts_rh) {
- ip6_redirect_no_header(skb, dev_net(skb->dev), 0, 0);
+ ip6_redirect_no_header(skb, dev_net(skb->dev),
+ skb->dev->ifindex, 0);
return;
}