From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Ahern Subject: Re: [PATCH] netlink: Add netns check on taps Date: Tue, 5 Dec 2017 19:19:49 -0700 Message-ID: References: <1512513982-20407-1-git-send-email-cernekee@chromium.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Cc: johannes.berg@intel.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org To: Kevin Cernekee , davem@davemloft.net Return-path: In-Reply-To: <1512513982-20407-1-git-send-email-cernekee@chromium.org> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On 12/5/17 3:46 PM, Kevin Cernekee wrote: > Currently, a nlmon link inside a child namespace can observe systemwide > netlink activity. Filter the traffic so that in a non-init netns, > 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 abc123 /tmp/nlmon.pcap > > Signed-off-by: Kevin Cernekee > --- > net/netlink/af_netlink.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c > index b9e0ee4..88381a2 100644 > --- a/net/netlink/af_netlink.c > +++ b/net/netlink/af_netlink.c > @@ -253,6 +253,11 @@ 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)) && > + !net_eq(dev_net(dev), &init_net)) { Why is init_net special? Seems like snooping should be limited to the namespace you are in.