[Trusty][Xenial][Zesty][Artful][PATCH 1/1][v3] CVE-2017-17449 netlink: Add netns check on taps
Khalid Elmously
khalid.elmously at canonical.com
Thu Jan 4 14:52:18 UTC 2018
From: Kevin Cernekee <cernekee at chromium.org>
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 at chromium.org>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Khalid Elmously <khalid.elmously at canonical.com>
---
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 7e794ad50cb0..3c7a3002f718 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))
--
2.14.1
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