linux-kernel - [PATCH 3.12 33/64] bridge: Only call /sbin/bridge-stp for the initial network namespace

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Message-Id: <c33d035b4056b4384885e284ed302c3545efb6eb.1455198893.git.jslaby@suse.cz>
Date:	Thu, 11 Feb 2016 14:59:09 +0100
From:	Jiri Slaby <jslaby@...e.cz>
To:	stable@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org,
	Hannes Frederic Sowa <hannes@...essinduktion.org>,
	"Eric W . Biederman" <ebiederm@...ssion.com>,
	"David S . Miller" <davem@...emloft.net>,
	Jiri Slaby <jslaby@...e.cz>
Subject: [PATCH 3.12 33/64] bridge: Only call /sbin/bridge-stp for the initial network namespace

From: Hannes Frederic Sowa <hannes@...essinduktion.org>

3.12-stable review patch.  If anyone has any objections, please let me know.

===============

[ Upstream commit ff62198553e43cdffa9d539f6165d3e83f8a42bc ]

[I stole this patch from Eric Biederman. He wrote:]

> 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.

[Hannes: changed patch using netns_eq]

Cc: Eric W. Biederman <ebiederm@...ssion.com>
Signed-off-by: Eric W. Biederman <ebiederm@...ssion.com>
Signed-off-by: Hannes Frederic Sowa <hannes@...essinduktion.org>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Jiri Slaby <jslaby@...e.cz>
---
 net/bridge/br_stp_if.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/net/bridge/br_stp_if.c b/net/bridge/br_stp_if.c
index 886f6d6dc48a..3995a66c3e4e 100644
--- a/net/bridge/br_stp_if.c
+++ b/net/bridge/br_stp_if.c
@@ -128,7 +128,10 @@ static void br_stp_start(struct net_bridge *br)
 	char *argv[] = { BR_STP_PROG, br->dev->name, "start", NULL };
 	char *envp[] = { NULL };
 
-	r = call_usermodehelper(BR_STP_PROG, argv, envp, UMH_WAIT_PROC);
+	if (net_eq(dev_net(br->dev), &init_net))
+		r = call_usermodehelper(BR_STP_PROG, argv, envp, UMH_WAIT_PROC);
+	else
+		r = -ENOENT;
 
 	spin_lock_bh(&br->lock);
 
-- 
2.7.1