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

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commit 6e540309326188f769e03bb4c6dd8ff6752930c2 upstream.

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>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
This commit is contained in:
Shawn Bohrer 2015-06-03 16:27:38 -05:00 committed by syphyr
parent 5023264f3f
commit 755cb66d68
1 changed files with 15 additions and 3 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

18
net/ipv4/udp.c
View file

@ -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>
@ -1919,6 +1920,7 @@ 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)))
@ -1928,14 +1930,24 @@ 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;