Hi Chris,

you wrote in <199412030849.DAA02790@pain.lcs.mit.edu>:
> No, they can mount things only if a certain set of conditions are met,
> namely:
> 	(1) they have appropriate permissions on the device's /dev
> 		entries

The program is SETUID to root. If root can't read the device, everyone
who calls "mount_ados" can it.

> 	(2) they have appropriate permissions on the to-be-mounted-on
> 		directory.

He can mount it to directory in it's home directory.

> did you actually try to mount your amigados partition as a 'random'
> user?

Yes.

> if it worked, what do the permissions on its device node look like?

They are correct, see below.
 
> don't assume that just because something is named "mount_*" and is
> set-id that anybody can use it to mount anything...

*YOU* should have tried before writing this mail:

Script started on Sat Dec  3 21:17:50 1994
tron@lyssa:~>mkdir /tmp/bla
                   ^^^^^^^^
User created directory.

tron@lyssa:~>mount_ados /tmp/blatron@lyssa:~>ls -l /dev/sd0e /sbin/mount_ados brw-r-----  1 root  operator    4,   4 Nov 23 23:18 /dev/sd0e

[      ^^^ => not readable for "tron".]

-r-sr-xr-x  1 root  bin         106496 Oct 21 04:36 /sbin/mount_ados

[   ^ :-( I changed it back to the original. ]

tron@lyssa:~>mount_ados /dev/sd0e /tmp/bla
tron@lyssa:~>df
Filesystem  512-blocks     Used    Avail Capacity  Mounted on
/dev/sd1a       395722   228760   147174    61%    /
/dev/sd0f       137770    85314    45566    65%    /home1
/dev/cd0a      1298000  1298000        0   100%    /cdrom
adosfs               2        2        0   100%    /fatty
procfs              16       16        0   100%    /proc
kernfs               2        2        0   100%    /kern
adosfs               2        2        0   100%    /tmp/bla

[Seen it ? It worked.]

tron@lyssa:~>umount /tmp/bla
umount: /tmp/bla: Operation not permitted

[As I said: unmounting does NOT work.]

tron@lyssa:~>su
Password:
tron@lyssa:/homes/lyssa/tron#umount /tmp/bla
tron@lyssa:/homes/lyssa/tron#^Dexit
tron@lyssa:~>rmdir /tmp/bla
tron@lyssa:~>^Dexit

Script done on Sat Dec  3 21:18:46 1994

-- 
Matthias Scheler
tron@lyssa.owl.de