This is a note to let you know that I've just added the patch titled
vfs: Add a mount flag to lock read only bind mounts
to the 3.8-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
vfs-add-a-mount-flag-to-lock-read-only-bind-mounts.patch
and it can be found in the queue-3.8 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 90563b198e4c6674c63672fae1923da467215f45 Mon Sep 17 00:00:00 2001
From: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Date: Fri, 22 Mar 2013 03:10:15 -0700
Subject: vfs: Add a mount flag to lock read only bind mounts
From: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
commit 90563b198e4c6674c63672fae1923da467215f45 upstream.
When a read-only bind mount is copied from mount namespace in a higher
privileged user namespace to a mount namespace in a lesser privileged
user namespace, it should not be possible to remove the the read-only
restriction.
Add a MNT_LOCK_READONLY mount flag to indicate that a mount must
remain read-only.
Acked-by: Serge Hallyn <serge.hallyn@xxxxxxxxxxxxx>
Signed-off-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/namespace.c | 3 +++
include/linux/mount.h | 2 ++
2 files changed, 5 insertions(+)
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1736,6 +1736,9 @@ static int change_mount_flags(struct vfs
if (readonly_request == __mnt_is_readonly(mnt))
return 0;
+ if (mnt->mnt_flags & MNT_LOCK_READONLY)
+ return -EPERM;
+
if (readonly_request)
error = mnt_make_readonly(real_mount(mnt));
else
--- a/include/linux/mount.h
+++ b/include/linux/mount.h
@@ -47,6 +47,8 @@ struct mnt_namespace;
#define MNT_INTERNAL 0x4000
+#define MNT_LOCK_READONLY 0x400000
+
struct vfsmount {
struct dentry *mnt_root; /* root of the mounted tree */
struct super_block *mnt_sb; /* pointer to superblock */
Patches currently in stable-queue which might be from ebiederm@xxxxxxxxxxxx are
queue-3.8/vfs-carefully-propogate-mounts-across-user-namespaces.patch
queue-3.8/vfs-add-a-mount-flag-to-lock-read-only-bind-mounts.patch
queue-3.8/userns-don-t-allow-creation-if-the-user-is-chrooted.patch
queue-3.8/pid-handle-the-exit-of-a-multi-threaded-init.patch
queue-3.8/ipc-restrict-mounting-the-mqueue-filesystem.patch
queue-3.8/scm-require-cap_sys_admin-over-the-current-pidns-to-spoof-pids.patch
queue-3.8/userns-restrict-when-proc-and-sysfs-can-be-mounted.patch
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