From: "Eric W. Biederman" <ebiederm@xmission.com>
To: Linux Containers <containers@lists.linux-foundation.org>
Cc: linux-fsdevel@vger.kernel.org,
Seth Forshee <seth.forshee@canonical.com>,
"Serge E. Hallyn" <serge@hallyn.com>,
Christian Brauner <christian@brauner.io>,
linux-kernel@vger.kernel.org,
"Eric W. Biederman" <ebiederm@xmission.com>
Subject: [REVIEW][PATCH 4/6] fs: Allow superblock owner to access do_remount_sb()
Date: Wed, 23 May 2018 18:25:36 -0500 [thread overview]
Message-ID: <20180523232538.4880-4-ebiederm@xmission.com> (raw)
In-Reply-To: <87o9h6554f.fsf@xmission.com>
Superblock level remounts are currently restricted to global
CAP_SYS_ADMIN, as is the path for changing the root mount to
read only on umount. Loosen both of these permission checks to
also allow CAP_SYS_ADMIN in any namespace which is privileged
towards the userns which originally mounted the filesystem.
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
---
fs/namespace.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/fs/namespace.c b/fs/namespace.c
index 5f75969adff1..8ddd14806799 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1590,7 +1590,7 @@ static int do_umount(struct mount *mnt, int flags)
* Special case for "unmounting" root ...
* we just try to remount it readonly.
*/
- if (!capable(CAP_SYS_ADMIN))
+ if (!ns_capable(sb->s_user_ns, CAP_SYS_ADMIN))
return -EPERM;
down_write(&sb->s_umount);
if (!sb_rdonly(sb))
@@ -2333,7 +2333,7 @@ static int do_remount(struct path *path, int ms_flags, int sb_flags,
down_write(&sb->s_umount);
if (ms_flags & MS_BIND)
err = change_mount_flags(path->mnt, ms_flags);
- else if (!capable(CAP_SYS_ADMIN))
+ else if (!ns_capable(sb->s_user_ns, CAP_SYS_ADMIN))
err = -EPERM;
else
err = do_remount_sb(sb, sb_flags, data, 0);
--
2.14.1
next prev parent reply other threads:[~2018-05-23 23:26 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-23 23:22 [REVIEW][PATCH 0/6] Wrapping up the vfs support for unprivileged mounts Eric W. Biederman
2018-05-23 23:25 ` [REVIEW][PATCH 1/6] vfs: Don't allow changing the link count of an inode with an invalid uid or gid Eric W. Biederman
2018-05-24 12:58 ` Seth Forshee
2018-05-24 22:30 ` Christian Brauner
2018-05-23 23:25 ` [REVIEW][PATCH 2/6] vfs: Allow userns root to call mknod on owned filesystems Eric W. Biederman
2018-05-24 13:55 ` Seth Forshee
2018-05-24 16:55 ` Eric W. Biederman
2018-05-24 17:22 ` Seth Forshee
2018-05-24 19:12 ` Christian Brauner
2018-05-23 23:25 ` [REVIEW][PATCH 3/6] fs: Allow superblock owner to replace invalid owners of inodes Eric W. Biederman
2018-05-23 23:41 ` [REVIEW][PATCH v2 " Eric W. Biederman
2018-05-24 22:30 ` Christian Brauner
2018-05-23 23:25 ` Eric W. Biederman [this message]
2018-05-24 15:58 ` [REVIEW][PATCH 4/6] fs: Allow superblock owner to access do_remount_sb() Christian Brauner
2018-05-24 16:45 ` Eric W. Biederman
2018-05-24 17:28 ` Christian Brauner
2018-05-23 23:25 ` [REVIEW][PATCH 5/6] capabilities: Allow privileged user in s_user_ns to set security.* xattrs Eric W. Biederman
2018-05-24 15:57 ` Christian Brauner
2018-05-23 23:25 ` [REVIEW][PATCH 6/6] fs: Allow CAP_SYS_ADMIN in s_user_ns to freeze and thaw filesystems Eric W. Biederman
2018-05-24 15:59 ` Christian Brauner
2018-05-24 21:46 ` [REVIEW][PATCH 0/6] Wrapping up the vfs support for unprivileged mounts Theodore Y. Ts'o
2018-05-24 23:23 ` Eric W. Biederman
2018-05-25 3:57 ` Dave Chinner
2018-05-25 4:06 ` Darrick J. Wong
2018-05-29 13:12 ` Eric W. Biederman
2018-05-29 22:17 ` Dave Chinner
2018-05-30 2:34 ` Eric W. Biederman
2018-05-30 4:34 ` Dave Chinner
2018-05-29 15:40 ` Dongsu Park
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