[PATCH 039/150] net: ipv6: Don't purge default router if accept_ra=2

[Luis Henriques]

3.5.7.9 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Lorenzo Colitti <lorenzo at google.com>

commit 3e8b0ac3e41e3c882222a5522d5df7212438ab51 upstream.

Setting net.ipv6.conf.<interface>.accept_ra=2 causes the kernel
to accept RAs even when forwarding is enabled. However, enabling
forwarding purges all default routes on the system, breaking
connectivity until the next RA is received. Fix this by not
purging default routes on interfaces that have accept_ra=2.

Signed-off-by: Lorenzo Colitti <lorenzo at google.com>
Acked-by: YOSHIFUJI Hideaki <yoshfuji at linux-ipv6.org>
Acked-by: Eric Dumazet <edumazet at google.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Luis Henriques <luis.henriques at canonical.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 08c149c..577bb2f 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -1971,7 +1971,8 @@ void rt6_purge_dflt_routers(struct net *net)
 restart:
 	read_lock_bh(&table->tb6_lock);
 	for (rt = table->tb6_root.leaf; rt; rt = rt->dst.rt6_next) {
-		if (rt->rt6i_flags & (RTF_DEFAULT | RTF_ADDRCONF)) {
+		if (rt->rt6i_flags & (RTF_DEFAULT | RTF_ADDRCONF) &&
+		    (!rt->rt6i_idev || rt->rt6i_idev->cnf.accept_ra != 2)) {
 			dst_hold(&rt->dst);
 			read_unlock_bh(&table->tb6_lock);
 			ip6_del_rt(rt);
-- 
1.8.1.2