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Commit 6e540309 authored by Shawn Bohrer's avatar Shawn Bohrer Committed by David S. Miller
Browse files

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



421b3885 "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: default avatarShawn Bohrer <sbohrer@rgmadvisors.com>
Reported-by: default avatarYurij M. Plotnikov <Yurij.Plotnikov@oktetlabs.ru>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 640b2b10

net/ipv4/udp.c

+15 −3
Original line number Diff line number Diff line
@@ -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>
@@ -1960,6 +1961,7 @@ 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)))
@@ -1969,14 +1971,24 @@ 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;