lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite for Android: free password hash cracker in your pocket
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:   Wed, 22 Nov 2017 22:23:55 +0000
From:   alexander.levin@...izon.com
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
Cc:     "Eric W. Biederman" <ebiederm@...ssion.com>,
        alexander.levin@...izon.com
Subject: [PATCH AUTOSEL for 4.9 16/54] libfs: Modify mount_pseudo_xattr to be
 clear it is not a userspace mount

From: "Eric W. Biederman" <ebiederm@...ssion.com>

[ Upstream commit 75422726b0f717d67db3283c2eb5bc14fa2619c5 ]

Add MS_KERNMOUNT to the flags that are passed.
Use sget_userns and force &init_user_ns instead of calling sget so that
even if called from a weird context the internal filesystem will be
considered to be in the intial user namespace.

Luis Ressel reported that the the failure to pass MS_KERNMOUNT into
mount_pseudo broke his in development graphics driver that uses the
generic drm infrastructure.  I am not certain the deriver was bug
free in it's usage of that infrastructure but since
mount_pseudo_xattr can never be triggered by userspace it is clearer
and less error prone, and less problematic for the code to be explicit.

Reported-by: Luis Ressel <aranea@...ah.de>
Tested-by: Luis Ressel <aranea@...ah.de>
Acked-by: Al Viro <viro@...IV.linux.org.uk>
Signed-off-by: "Eric W. Biederman" <ebiederm@...ssion.com>
Signed-off-by: Sasha Levin <alexander.levin@...izon.com>
---
 fs/libfs.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/libfs.c b/fs/libfs.c
index 48826d4da189..9588780ad43e 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -245,7 +245,8 @@ struct dentry *mount_pseudo_xattr(struct file_system_type *fs_type, char *name,
 	struct inode *root;
 	struct qstr d_name = QSTR_INIT(name, strlen(name));
 
-	s = sget(fs_type, NULL, set_anon_super, MS_NOUSER, NULL);
+	s = sget_userns(fs_type, NULL, set_anon_super, MS_KERNMOUNT|MS_NOUSER,
+			&init_user_ns, NULL);
 	if (IS_ERR(s))
 		return ERR_CAST(s);
 
-- 
2.11.0

Powered by blists - more mailing lists