From: Kevin Cernekee <cernekee@chromium.org>
Date: Wed, 6 Dec 2017 12:12:27 -0800
Subject: netlink: Add netns check on taps
Patch-mainline: v4.15-rc4
Git-commit: 93c647643b48f0131f02e45da3bd367d80443291
References: CVE-2017-17449 bsc#1071694
Currently, a nlmon link inside a child namespace can observe systemwide
netlink activity. Filter the traffic so that nlmon can only sniff
netlink messages from its own netns.
Test case:
vpnns -- bash -c "ip link add nlmon0 type nlmon; \
ip link set nlmon0 up; \
tcpdump -i nlmon0 -q -w /tmp/nlmon.pcap -U" &
sudo ip xfrm state add src 10.1.1.1 dst 10.1.1.2 proto esp \
spi 0x1 mode transport \
auth sha1 0x6162633132330000000000000000000000000000 \
enc aes 0x00000000000000000000000000000000
grep --binary abc123 /tmp/nlmon.pcap
Signed-off-by: Kevin Cernekee <cernekee@chromium.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Michal Kubecek <mkubecek@suse.cz>
---
net/netlink/af_netlink.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 464e57216d87..4f528bac7f4d 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -254,6 +254,9 @@ static int __netlink_deliver_tap_skb(struct sk_buff *skb,
struct sock *sk = skb->sk;
int ret = -ENOMEM;
+ if (!net_eq(dev_net(dev), sock_net(sk)))
+ return 0;
+
dev_hold(dev);
if (is_vmalloc_addr(skb->head))
--
2.15.1