net: ipv6: Don't purge default router if accept_ra=2

[ Upstream commit 3e8b0ac3e41e3c882222a5522d5df7212438ab51 ]

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@google.com>
Acked-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 791c1fa879b27cfad4a3eed6533dc6a0a82b0240..18ea73c5d628c43d555dcd9f3786139a1ca8bae3 100644 (file)
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -1920,7 +1920,8 @@ 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);