[tlug] Re: CD Writers

[Mike Fabian <mfabian@example.com>]

Stuart Luppescu <s-luppescu@example.com> writes:

> On 月, 2002-03-04 at 10:08, Shimpei Yamashita wrote:
>> On Mon, Mar 04, 2002 at 08:57:56AM -0600,
>> Stuart Luppescu wrote:
>> > > > /usr/bin/cdrecord: Operation not permitted. WARNING: Cannot do
>> > > > mlockall(2).
>> 
>> This one disables paging for a block of memory.
>> 
>> > > > /usr/bin/cdrecord: Permission denied. WARNING: Cannot set priority using
>> > > > setpriority().
>> 
>> And this one lowers a process's priority.  For understandable reasons,
>> both of these system calls require root access.  It has nothing to do with
>> file permissions.  cdrecord may be using other privileged calls, too.
>
> Yup. That's what I thought. So, the instructions on the gcombust page
> (http://www.abo.fi/~jmunsin/gcombust/FAQ.shtml) about getting it to work
> as a regular user ("gcombust shouldn't be ran as root") are ...
> irrelevant? contradictory? misleading? The only alternative is to make
> cdrecord setgid and give the group executable rights, I guess.

The following part from the 'cdrecord' man-page explains it:

man cdrecord>      If  you  don't  want to allow users to become root on your
man cdrecord>       system, cdrecord may safely be installed suid  root.  This
man cdrecord>       allows  all  users or a group of users with no root privi-
man cdrecord>       leges to use cdrecord.  Cdrecord in this case  checks,  if
man cdrecord>       the  real  user would have been able to read the specified
man cdrecord>       files.  To give all user access to use cdrecord, enter:
man cdrecord>
man cdrecord>            chown root /usr/local/bin/cdrecord
man cdrecord>            chmod 4711 /usr/local/bin/cdrecord
man cdrecord>
man cdrecord>       To give a restricted group of  users  access  to  cdrecord
man cdrecord>       enter:
man cdrecord>
man cdrecord>            chown root /usr/local/bin/cdrecord
man cdrecord>            chgrp cdburners /usr/local/bin/cdrecord
man cdrecord>            chmod 4710 /usr/local/bin/cdrecord
man cdrecord>
man cdrecord>       and add a group cdburners on your system.
man cdrecord>
man cdrecord>       Never  give  write  permissions  for non root users to the
man cdrecord>       /dev/scg?  devices  unless  you  would  allow  anybody  to
man cdrecord>       read/write/format all your disks.

-- 
Mike Fabian   <mfabian@example.com>   http://www.suse.de/~mfabian
睡眠不足はいい仕事の敵だ。