From mboxrd@z Thu Jan 1 00:00:00 1970 From: ebiederm@xmission.com (Eric W. Biederman) Subject: [PATCH net] bridge: Only call /sbin/bridge-stp for the initial network namespace Date: Mon, 30 Nov 2015 15:38:15 -0600 Message-ID: <87egf7183c.fsf_-_@x220.int.ebiederm.org> References: <565B7F7D.80208@nod.at> Mime-Version: 1.0 Content-Type: text/plain Cc: Kees Cook , "kernel-hardening@lists.openwall.com" , Richard Weinberger , bridge@lists.linux-foundation.org, "linux-kernel@vger.kernel.org" , "netdev@vger.kernel.org" To: David Miller Return-path: In-Reply-To: (Kees Cook's message of "Mon, 30 Nov 2015 12:14:41 -0800") List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: bridge-bounces@lists.linux-foundation.org Errors-To: bridge-bounces@lists.linux-foundation.org List-Id: netdev.vger.kernel.org There is no defined mechanism to pass network namespace information into /sbin/bridge-stp therefore don't even try to invoke it except for bridge devices in the initial network namespace. It is possible for unprivileged users to cause /sbin/bridge-stp to be invoked for any network device name which if /sbin/bridge-stp does not guard against unreasonable arguments or being invoked twice on the same network device could cause problems. Signed-off-by: "Eric W. Biederman" --- net/bridge/br_stp_if.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/net/bridge/br_stp_if.c b/net/bridge/br_stp_if.c index 5396ff08af32..742fa89528ab 100644 --- a/net/bridge/br_stp_if.c +++ b/net/bridge/br_stp_if.c @@ -142,7 +142,9 @@ static void br_stp_start(struct net_bridge *br) char *envp[] = { NULL }; struct net_bridge_port *p; - r = call_usermodehelper(BR_STP_PROG, argv, envp, UMH_WAIT_PROC); + r = -ENOENT; + if (dev_net(br->dev) == &init_net) + r = call_usermodehelper(BR_STP_PROG, argv, envp, UMH_WAIT_PROC); spin_lock_bh(&br->lock); -- 2.2.1