netdev - [PATCH] net:ppp: replace too strict capability restriction on opening /dev/ppp

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Message-Id: <15AED149-BC4D-4B8F-B173-3F652A46FA35@tuna.tsinghua.edu.cn>
Date:	Sun, 19 Jun 2016 07:21:27 +0200
From:	Shanker Wang <miao.wang@...a.tsinghua.edu.cn>
To:	netdev@...r.kernel.org
Cc:	Hannes Frederic Sowa <hannes@...essinduktion.org>,
	Richard Weinberger <richard.weinberger@...il.com>,
	Guillaume Nault <g.nault@...halink.fr>,
	王邈 <shankerwangmiao@...il.com>
Subject: [PATCH] net:ppp: replace too strict capability restriction on opening  /dev/ppp

This patch removes the check for CAP_NET_ADMIN in the initial namespace
when opening /dev/open. Instead, CAP_NET_ADMIN is checked in the user
namespace the net namespace was created so that /dev/ppp cat get opened
in a unprivileged container.

Cc: Hannes Frederic Sowa <hannes@...essinduktion.org>
Cc: Richard Weinberger <richard.weinberger@...il.com>
Cc: Guillaume Nault <g.nault@...halink.fr>
Cc: Miao Wang <shankerwangmiao@...il.com>
Signed-off-by: Miao Wang <miao.wang@...a.tsinghua.edu.cn>
---
drivers/net/ppp/ppp_generic.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ppp/ppp_generic.c b/drivers/net/ppp/ppp_generic.c
index f572b31..4b3b2b5 100644
--- a/drivers/net/ppp/ppp_generic.c
+++ b/drivers/net/ppp/ppp_generic.c
@@ -380,7 +380,7 @@ static int ppp_open(struct inode *inode, struct file *file)
	/*
	 * This could (should?) be enforced by the permissions on /dev/ppp.
	 */
-	if (!capable(CAP_NET_ADMIN))
+	if (!ns_capable(current->nsproxy->net_ns->user_ns, CAP_NET_ADMIN))
		return -EPERM;
	return 0;
}
-- 
2.5.2