*BSD News Article 45975


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From: lyndon@orthanc.com (Lyndon Nerenberg)
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: Re: Suggestion for 2.1
Date: 17 Jun 1995 23:55:39 -0700
Organization: Orthanc Systems
Lines: 38
Message-ID: <3s0ils$7i9@multivac.orthanc.com>
References: <3r7888$280@germany.eu.net> <3r80ka$bun@iii1.iii.net> <3rh7k3$mcb@bonnie.tcd-dresden.de> <3rif0f$e3t@oz.plymouth.edu>
NNTP-Posting-Host: multivac.orthanc.com

ted@oz.plymouth.edu (Ted Wisniewski) writes:

[ About dynamic non-root mounts of CD and flops ]

>	I will volunteer to do this if it is desired....   I have already
>done something that does this.   I would have to clean up the code a little
>but it should not be too difficult.   I will write it up and post it
>if it is needed immediately.  I just have to add some code to check

>	1.	Is the device already mounted.
>	2.	See if user is in the list of people allowed to mount the 
>		device (I think this would be a necessary addition)

How about taking a lesson from SGI's Irix. They have a system daemon
(mediad) that looks for media insertion in the CDROM and flop drives.
When something new comes along the daemon determines the FS type and
does the mount. No root access required, and the latency is very
low (5-10 seconds). Unmounts are handled via the "eject" command
with arguments of "cdrom" or "floppy" respectively (or something very
similar).

>	4.	Set up a prg that does the umount as well (equally restricted)
>		to certain devices.

In the case of Irix, the eject command is unrestricted (as I recall). Since
mounts are also unrestricted under this scheme, it makes sense.

An alternative would be to have mediad listen on a socket or named pipe
for a user mount request, and tag a uid to it. Unmounts could then be
restricted to that uid (tracked on a per device basis.)

--lyndon


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