> On Sat, Feb 23, 2008 at 06:33:13PM +0100, Miklos Szeredi wrote: > > > c) just what is limited by that sysctl? AFAICS, rbind is allowed > > > if mountpoint is on user vfsmount and it seems to create vfsmounts without > > > eating into that limit just fine... What's the point of limiting the > > > amount of vfsmounts marked user when you do not limit the number of vfsmount > > > one can allocate? > > > > The limit is there, so that unprivileged users cannot create insane > > number of mounts. It's just a safety thing, analogous to > > /proc/sys/fs/file-max. > > Can't they? Looks like one can create any number of vfsmounts without > getting more than one marked MNT_USER... permit_mount() will set MS_SETUSER in flags, and do_loopback() will set CL_SETUSER based on that flag. > If you are trying to limit the number of superblocks (i.e. active instances > of filesystems), then I'd say that vfsmounts make piss-poor proxies for > those and it would be better to count the objects you really want to count... I think I really want to limit vfsmounts. But not because these take so much memory or anything, just to be safe against a stupid users playing rbind and propagation, and things like that. 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
