Patch "ipv4/udp: Verify multicast group is ours in upd_v4_early_demux()" has been added to the 4.0-stable tree

This is a note to let you know that I've just added the patch titled

ipv4/udp: Verify multicast group is ours in upd_v4_early_demux()

to the 4.0-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
ipv4-udp-verify-multicast-group-is-ours-in-upd_v4_early_demux.patch
and it can be found in the queue-4.0 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Shawn Bohrer <[email protected]>
Date: Wed, 3 Jun 2015 16:27:38 -0500
Subject: ipv4/udp: Verify multicast group is ours in upd_v4_early_demux()

From: Shawn Bohrer <[email protected]>

[ Upstream commit 6e540309326188f769e03bb4c6dd8ff6752930c2 ]

421b3885bf6d56391297844f43fb7154a6396e12 "udp: ipv4: Add udp early demux" introduced a regression that allowed sockets bound to INADDR_ANY to receive packets from multicast groups that the socket had not joined. For example a socket that had joined 224.168.2.9 could also receive packets from 225.168.2.9 despite not having joined that group if ip_early_demux is enabled.

Fix this by calling ip_check_mc_rcu() in udp_v4_early_demux() to verify that the multicast packet is indeed ours.

---
 net/ipv4/udp.c |   18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

@@ -90,6 +90,7 @@
 #include <linux/socket.h>
 #include <linux/sockios.h>
 #include <linux/igmp.h>
+#include <linux/inetdevice.h>
 #include <linux/in.h>
 #include <linux/errno.h>
 #include <linux/timer.h>

@@ -1966,6 +1967,7 @@ void udp_v4_early_demux(struct sk_buff *
 	struct sock *sk;
 	struct dst_entry *dst;
 	int dif = skb->dev->ifindex;
+	int ours;
 
 	/* validate the packet */
 	if (!pskb_may_pull(skb, skb_transport_offset(skb) + sizeof(struct udphdr)))

@@ -1975,14 +1977,24 @@ void udp_v4_early_demux(struct sk_buff *
 	uh = udp_hdr(skb);
 
 	if (skb->pkt_type == PACKET_BROADCAST ||
-	    skb->pkt_type == PACKET_MULTICAST)
+	    skb->pkt_type == PACKET_MULTICAST) {
+		struct in_device *in_dev = __in_dev_get_rcu(skb->dev);
+
+		if (!in_dev)
+			return;
+
+		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)
+	} else if (skb->pkt_type == PACKET_HOST) {
 		sk = __udp4_lib_demux_lookup(net, uh->dest, iph->daddr,
 					     uh->source, iph->saddr, dif);
-	else
+	} else {
 		return;
+	}
 
 	if (!sk)
 		return;

Patches currently in stable-queue which might be from [email protected] are

queue-4.0/ipv4-udp-verify-multicast-group-is-ours-in-upd_v4_early_demux.patch