lkml.org 
[lkml]   [2015]   [Jan]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 3.17 45/73] umount: Disallow unprivileged mount force
    Date
    3.17-stable review patch.  If anyone has any objections, please let me know.

    ------------------

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

    commit b2f5d4dc38e034eecb7987e513255265ff9aa1cf upstream.

    Forced unmount affects not just the mount namespace but the underlying
    superblock as well. Restrict forced unmount to the global root user
    for now. Otherwise it becomes possible a user in a less privileged
    mount namespace to force the shutdown of a superblock of a filesystem
    in a more privileged mount namespace, allowing a DOS attack on root.

    Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    fs/namespace.c | 3 +++
    1 file changed, 3 insertions(+)

    --- a/fs/namespace.c
    +++ b/fs/namespace.c
    @@ -1432,6 +1432,9 @@ SYSCALL_DEFINE2(umount, char __user *, n
    goto dput_and_out;
    if (mnt->mnt.mnt_flags & MNT_LOCKED)
    goto dput_and_out;
    + retval = -EPERM;
    + if (flags & MNT_FORCE && !capable(CAP_SYS_ADMIN))
    + goto dput_and_out;

    retval = do_umount(mnt, flags);
    dput_and_out:



    \
     
     \ /
      Last update: 2015-01-07 03:41    [W:4.024 / U:0.216 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site