On Sat, 8 Sep 2007, Antti Harri wrote: > Hello, > > First just plain directory with mode=700: > > drwx------ 43 root wheel 2048 Sep 7 22:24 /backups/ > > Then I mount filesystem under /backups: > > /dev/sd0i on /backups type ffs (local, softdep) > drwxr-x--- 43 root wheel 2048 Sep 7 22:24 /backups/ > > The permissions changed, so far good because I've changed > the modes of the mounted volume to 750. > > Then as a normal user belonging to 'wheel' I do: > > $ ls -la /backups/ > ls: /backups/..: Permission denied > [rest of the files are listed normally, including '.'] > > $ stat /backups/.. > stat: /backups/..: Permission denied > > Doing those as root is fine. > > I asked my friend to reproduce this on Linux but > he was unable get any weird errors, therefore > I'm asking here. :-)
You're clearly accessing /backups/.. according to the permissions (700) of the mount point, /backups, not the root directory of the mounted volume, which is what you see with ls and stat for /backups after the mount. (This can be demonstrated by umounting /backups, chmoding /backups to 750, remounting and trying again.) As far as I know, this is normal operation for ffs/BSD. My *guess* is that this feature may serve to stifle a way of leveraging permissions through mounting, but, I repeat, that's a guess. Linux may well have different fs semantics (it definitely does in other aspects of file system permissions); it's System-V-ish, not BSD-ish. It's not a guide, therefore, in these file-system semantics problems. Dave -- "America ... might become dictatress of the world. She would be no longer the ruler of her own spirit." -- John Quincy Adams, July 4, 1821