Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752654AbdLEWzQ (ORCPT ); Tue, 5 Dec 2017 17:55:16 -0500 Received: from mail-pg0-f68.google.com ([74.125.83.68]:44551 "EHLO mail-pg0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752390AbdLEWzM (ORCPT ); Tue, 5 Dec 2017 17:55:12 -0500 X-Google-Smtp-Source: AGs4zMbxVBDkS+17iao4O4UJXT/VJcJyPehg9jWDRzdaxGr/LDC8Ab+PBBIVhSJA3jLcwpjNm9oSFg== From: Kevin Cernekee To: davem@davemloft.net Cc: johannes.berg@intel.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] netlink: Add netns check on taps Date: Tue, 5 Dec 2017 14:46:22 -0800 Message-Id: <1512513982-20407-1-git-send-email-cernekee@chromium.org> X-Mailer: git-send-email 2.7.4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1210 Lines: 38 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)) { + return 0; + } + dev_hold(dev); if (is_vmalloc_addr(skb->head)) -- 2.7.4