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From: Alexey Gladkov <gladkov.alexey@gmail.com>
To: LKML <linux-kernel@vger.kernel.org>
Cc: Linux FS Devel <linux-fsdevel@vger.kernel.org>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Alexey Gladkov <legion@kernel.org>,
	"Eric W . Biederman" <ebiederm@xmission.com>,
	Kees Cook <keescook@chromium.org>
Subject: [PATCH v1 2/2] Show /proc/self/net only for CAP_NET_ADMIN
Date: Mon, 27 Jul 2020 16:14:11 +0200
Message-ID: <20200727141411.203770-3-gladkov.alexey@gmail.com> (raw)
In-Reply-To: <20200727141411.203770-1-gladkov.alexey@gmail.com>

Show /proc/self/net only for CAP_NET_ADMIN if procfs is mounted with
subset=pid option in user namespace. This is done to avoid possible
information leakage.

Signed-off-by: Alexey Gladkov <gladkov.alexey@gmail.com>
---
 fs/proc/proc_net.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/fs/proc/proc_net.c b/fs/proc/proc_net.c
index dba63b2429f0..11fa2c4b3529 100644
--- a/fs/proc/proc_net.c
+++ b/fs/proc/proc_net.c
@@ -275,6 +275,12 @@ static struct net *get_proc_task_net(struct inode *dir)
 	struct task_struct *task;
 	struct nsproxy *ns;
 	struct net *net = NULL;
+	struct proc_fs_info *fs_info = proc_sb_info(dir->i_sb);
+
+	if ((fs_info->pidonly == PROC_PIDONLY_ON) &&
+	    (current_user_ns() != &init_user_ns) &&
+	    !capable(CAP_NET_ADMIN))
+		return net;
 
 	rcu_read_lock();
 	task = pid_task(proc_pid(dir), PIDTYPE_PID);
-- 
2.25.4


  parent reply index

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-27 14:14 [PATCH v1 0/2] proc: Relax check of mount visibility Alexey Gladkov
2020-07-27 14:14 ` [PATCH v1 1/2] " Alexey Gladkov
2020-07-27 14:14 ` Alexey Gladkov [this message]
2020-07-27 16:29   ` [PATCH v1 2/2] Show /proc/self/net only for CAP_NET_ADMIN Eric W. Biederman
2020-07-28 13:54     ` Alexey Gladkov
2020-07-31 16:10     ` [PATCH v2 " Alexey Gladkov

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