*statfs exposure of file system IDs to non-root users

[Terry Lambert]

Ian Dowse wrote:
> See previous posts here on the subject of unmounting by filesystem
> ID. The filesystem ID is a way of unambiguously specifying which
> file system is to be unmounted, whereas the mountpoint or device
> node may not be unique.

Yes, I'm aware of this facility for breaking sub-mounts.  8-).  The
implementation of mounts needs to change so that the mounts occur
in the higher layers, rather than the lower, for the covered vnode.


> The umount utility now passes a filesystem
> ID to unmount(2), which works fine when run by root and when umount
> is extracting an entry from the list obtained from getfsstat(2),
> but it doesn't work as a normal user when the ID comes from statfs(2).

Normal users should not be permitted to unmount /.  8-).

-- Terry