diff mbox

[v2] ipv4/udp: Verify multicast group is ours in upd_v4_early_demux()

Message ID 1433366858-14317-1-git-send-email-shawn.bohrer@gmail.com
State Accepted, archived
Delegated to: David Miller
Headers show

Commit Message

Shawn Bohrer June 3, 2015, 9:27 p.m. UTC 
From: Shawn Bohrer <sbohrer@rgmadvisors.com>

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.

Signed-off-by: Shawn Bohrer <sbohrer@rgmadvisors.com>
Reported-by: Yurij M. Plotnikov <Yurij.Plotnikov@oktetlabs.ru>
---

Coding style fixes.  Added braces around if branches, and inverted logic
to avoid long lines.

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

Comments

David Miller June 4, 2015, 7:46 a.m. UTC | #1 
From: Shawn Bohrer <shawn.bohrer@gmail.com>
Date: Wed,  3 Jun 2015 16:27:38 -0500

> From: Shawn Bohrer <sbohrer@rgmadvisors.com>
> 
> 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.
> 
> Signed-off-by: Shawn Bohrer <sbohrer@rgmadvisors.com>
> Reported-by: Yurij M. Plotnikov <Yurij.Plotnikov@oktetlabs.ru>

Applied and queued up for -stable, thanks.
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diff mbox

Patch

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index d10b7e0..df1b285 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -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>
@@ -1962,6 +1963,7 @@  void udp_v4_early_demux(struct sk_buff *skb)
 	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)))
@@ -1971,14 +1973,24 @@  void udp_v4_early_demux(struct sk_buff *skb)
 	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;