On Fri, Dec 12, 2014 at 2:48 PM, Eric W. Biederman <ebiederm@xxxxxxxxxxxx> wrote: > 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. > I thought I already fixed this. Did I miss part of it? > Cc: stable@xxxxxxxxxxxxxxx > Signed-off-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx> > --- > fs/namespace.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/fs/namespace.c b/fs/namespace.c > index 3a1a87dc33df..43b16af8af30 100644 > --- a/fs/namespace.c > +++ b/fs/namespace.c > @@ -1544,6 +1544,9 @@ SYSCALL_DEFINE2(umount, char __user *, name, int, flags) > 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: > -- > 1.9.1 > -- Andy Lutomirski AMA Capital Management, LLC -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html