On Sun, 21 Feb 2010, Al Viro wrote: > On Thu, Feb 11, 2010 at 12:21:00PM -0500, Christoph Hellwig wrote: > > On Wed, Feb 10, 2010 at 12:15:53PM +0100, Miklos Szeredi wrote: > > > - renamed flag to UMOUNT_NOFOLLOW > > > - added UMOUNT_UNUSED for feature detection > > > > Umm, why? MNT_ certainly isn't the best naming for unmount flags, > > but switching convention after we had a few doesn't make any sense. > > Actually, I've got more interesting question: what's being attempted > there? Is that just a "let's protect ourselves against somebody feeding > us an untrusted symlink"? I'm not sure if it makes much sense; if we > are dealing with pathnames on untrusted fs, there's nothing to stop the > attacker from having /mnt/foo/dir (originally containing a mountpoint > at /mnt/foo/dir/usr) killed and replaced with a symlink to /, making any > code that does umount() on such pathnames vulnerable as hell anyway. It is trivial to check the path up to the mountpoint (chdir + getcwd). But doing that on the mountpoint will make it busy, so NOFOLLOW is really needed there. Thanks, Miklos -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
