From: Kevin Cernekee cernekee@chromium.org
This patch has been added to the 4.1 stable tree. If you have any objections, please let us know.
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[ Upstream commit 93c647643b48f0131f02e45da3bd367d80443291 ]
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 Signed-off-by: Sasha Levin alexander.levin@microsoft.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 8daf2e44595a..66c340bc0553 100644 --- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -259,6 +259,9 @@ 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 (netlink_skb_is_mmaped(skb) || is_vmalloc_addr(skb->head))