On Wed, 2007-04-18 at 11:11 +0200, Miklos Szeredi wrote: > > > I've tried to make this unprivileged mount thing as simple as > > > possible, and no simpler. If we can make it even simpler, all the > > > better. > > > > We are certainly much more complex then the code in plan9 (just > > read through it) so I think we have room for improvement. > > > > Just for reference what I saw in plan 9 was: > > - No super user checks in it's mount, unmount, or namespace creation paths. > > - A flag to deny new mounts but not new bind mounts (for administrative purposes > > the comment said). > > > > Our differences from plan9. > > - suid capable binaries. (SUID please go away). > > - A history of programs assuming only root could call mount/unmount. > > I hate suid as well. _The_ motivation behind this patchset was to get > rid of "fusermount", a suid mount helper for fuse. > > But I don't think suid is going away, and definitely not overnight. > Also I don't think we want to require auditing userspace before > enabling user mounts. > > If I understand correctly, your proposal is to get rid of MNT_USER and > MNT_ALLOWUSERMNT and allow/deny unprivileged mounts and umounts based > on a boolean sysctl flag and on a check if the target namespace is the > initial namespace or not. And maybe add some extra checks which > prevent ugliness from happening with suid programs. Is this correct? > > If so, how are we going to make sure this won't break existing > userspace without doing a full audit of all suid programs in every > distro that wants this feature? > > Also how are we going to prevent the user from creating millions of > mounts, and using up all the kernel memory for vfsmounts? Don't forget that almost all mount flags are per-superblock. How are you planning on dealing with the case that one user mounts a filesystem read-only, while another is trying to mount the same one read-write? Trond - 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
