[PATCH] ipv6:examine the IP source address legitimacy

[Duan Jiong <duanj.fnst@cn.fujitsu.com>]

From: Duan Jiong <duanj.fnst@cn.fujitsu.com>

RFC4861 8.1:
The IP source address of the Redirect is the
same as the current first-hop router for the
specified ICMP Destination Address.

Signed-off-by: Duan Jiong <duanj.fnst@cn.fujitsu.com>
---
 net/ipv6/route.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 8d9a93e..d4f0f72 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -1685,6 +1685,7 @@ static int ip6_route_del(struct fib6_config *cfg)
 static void rt6_do_redirect(struct dst_entry *dst, struct sock *sk, struct sk_buff *skb)
 {
 	struct net *net = dev_net(skb->dev);
+	struct ipv6hdr *iph = ipv6_hdr(skb);
 	struct netevent_redirect netevent;
 	struct rt6_info *rt, *nrt = NULL;
 	struct ndisc_options ndopts;
@@ -1745,7 +1746,7 @@ static void rt6_do_redirect(struct dst_entry *dst, struct sock *sk, struct sk_bu
 	}
 
 	rt = (struct rt6_info *) dst;
-	if (rt == net->ipv6.ip6_null_entry) {
+	if (rt == net->ipv6.ip6_null_entry || !ipv6_addr_equal(&rt->rt6i_gateway, &iph->saddr)) {
 		net_dbg_ratelimited("rt6_redirect: source isn't a valid nexthop for redirect target\n");
 		return;
 	}
-- 
1.8.3.1