[PATCH 3.19.y-ckt 150/170] ipv4: fix broadcast packets reception

From: Kamal Mostafa
Date: Fri Apr 01 2016 - 21:03:39 EST


3.19.8-ckt18 -stable review patch. If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: Paolo Abeni <pabeni@xxxxxxxxxx>

commit ad0ea1989cc4d5905941d0a9e62c63ad6d859cef upstream.

Currently, ingress ipv4 broadcast datagrams are dropped since,
in udp_v4_early_demux(), ip_check_mc_rcu() is invoked even on
bcast packets.

This patch addresses the issue, invoking ip_check_mc_rcu()
only for mcast packets.

Fixes: 6e5403093261 ("ipv4/udp: Verify multicast group is ours in upd_v4_early_demux()")
Signed-off-by: Paolo Abeni <pabeni@xxxxxxxxxx>
Acked-by: Hannes Frederic Sowa <hannes@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
---
net/ipv4/udp.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index b833848..d569a84 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1985,10 +1985,14 @@ void udp_v4_early_demux(struct sk_buff *skb)
if (!in_dev)
return;

- ours = ip_check_mc_rcu(in_dev, iph->daddr, iph->saddr,
- iph->protocol);
- if (!ours)
- return;
+ /* we are supposed to accept bcast packets */
+ if (skb->pkt_type == PACKET_MULTICAST) {
+ ours = ip_check_mc_rcu(in_dev, iph->daddr, iph->saddr,
+ iph->protocol);
+ if (!ours)
+ return;
+ }
+
sk = __udp4_lib_mcast_demux_lookup(net, uh->dest, iph->daddr,
uh->source, iph->saddr, dif);
} else if (skb->pkt_type == PACKET_HOST) {
--
2.7.4