Hello,
Is it also needed by 3.2.x and 3.4.x ?
Thanks
On 08/25/2014 06:54 PM, Kamal Mostafa wrote:
> 3.8.13.28 -stable review patch. If anyone has any objections, please let me know.
>
> ------------------
>
> From: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
>
> commit a6138db815df5ee542d848318e5dae681590fccd upstream.
>
> Kenton Varda <kenton@xxxxxxxxxxxx> discovered that by remounting a
> read-only bind mount read-only in a user namespace the
> MNT_LOCK_READONLY bit would be cleared, allowing an unprivileged user
> to the remount a read-only mount read-write.
>
> Correct this by replacing the mask of mount flags to preserve
> with a mask of mount flags that may be changed, and preserve
> all others. This ensures that any future bugs with this mask and
> remount will fail in an easy to detect way where new mount flags
> simply won't change.
>
> Acked-by: Serge E. Hallyn <serge.hallyn@xxxxxxxxxx>
> Signed-off-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
> Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
> ---
> fs/namespace.c | 2 +-
> include/linux/mount.h | 4 +++-
> 2 files changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/fs/namespace.c b/fs/namespace.c
> index 5dd7709..ddbd5bc 100644
> --- a/fs/namespace.c
> +++ b/fs/namespace.c
> @@ -1782,7 +1782,7 @@ static int do_remount(struct path *path, int flags, int mnt_flags,
> err = do_remount_sb(sb, flags, data, 0);
> if (!err) {
> br_write_lock(&vfsmount_lock);
> - mnt_flags |= mnt->mnt.mnt_flags & MNT_PROPAGATION_MASK;
> + mnt_flags |= mnt->mnt.mnt_flags & ~MNT_USER_SETTABLE_MASK;
> mnt->mnt.mnt_flags = mnt_flags;
> br_write_unlock(&vfsmount_lock);
> }
> diff --git a/include/linux/mount.h b/include/linux/mount.h
> index 73005f9..16fc05d 100644
> --- a/include/linux/mount.h
> +++ b/include/linux/mount.h
> @@ -42,7 +42,9 @@ struct mnt_namespace;
> * flag, consider how it interacts with shared mounts.
> */
> #define MNT_SHARED_MASK (MNT_UNBINDABLE)
> -#define MNT_PROPAGATION_MASK (MNT_SHARED | MNT_UNBINDABLE)
> +#define MNT_USER_SETTABLE_MASK (MNT_NOSUID | MNT_NODEV | MNT_NOEXEC \
> + | MNT_NOATIME | MNT_NODIRATIME | MNT_RELATIME \
> + | MNT_READONLY)
>
>
> #define MNT_INTERNAL 0x4000
>
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