[PATCH nf 2/3] netfilter: nfnetlink: relax strict multicast group from netlink_bind

[Pablo Neira Ayuso <pablo@netfilter.org>]

Relax the checking that was introduced in 97840cb ("netfilter:
nfnetlink: fix insufficient validation in nfnetlink_bind") when the
subscription bitmask is used. Existing userspace code code may request
to listen to all of the existing netlink groups by setting an all to one
subscription group bitmask. Netlink already validates subscription via
setsockopt() for us.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 net/netfilter/nfnetlink.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/net/netfilter/nfnetlink.c b/net/netfilter/nfnetlink.c
index c6619d4..5082d81 100644
--- a/net/netfilter/nfnetlink.c
+++ b/net/netfilter/nfnetlink.c
@@ -469,8 +469,11 @@ static int nfnetlink_bind(int group)
 	const struct nfnetlink_subsystem *ss;
 	int type;
 
+	/* No strict check for groups when subscription bitmask is used, group
+	 * binding via setsockopt() already rejects this from netlink.
+	 */
 	if (group <= NFNLGRP_NONE || group > NFNLGRP_MAX)
-		return -EINVAL;
+		return 0;
 
 	type = nfnl_group2type[group];
 
-- 
1.7.10.4