Re: CUPS permissions
On Thu, Aug 26, 2021 at 11:31:30AM -0400, Greg Wooledge wrote:
> On Thu, Aug 26, 2021 at 04:25:54PM +0100, Brian wrote:
> > On Thu 26 Aug 2021 at 10:56:55 -0400, Greg Wooledge wrote:
> >
> > > On Thu, Aug 26, 2021 at 03:49:23PM +0100, Brian wrote:
> > > > On Thu 26 Aug 2021 at 06:18:21 -0700, Peter Ehlert wrote:
> > > >
> > > > [...]
> > > >
> > > > > > It would be useful to have the outputs of
> > > > > >
> > > > > > groups
> > > > > $ groups
> > > > > peter cdrom floppy audio dip video plugdev netdev
> > > > > >
> > > > > > and
> > > > > >
> > > > > > grep SystemGroup /etc/cups/cups-files.conf
> > > > > $ grep SystemGroup /etc/cups/cups-files.conf
> > > > > SystemGroup lpadmin
> > > > > >
> > > > > > from the OP.
> > > >
> > > > Follow Keith Bainbridge's advice and add your user to the lpadmin
> > > > group. Edit /etc/group and /etc/group- to do this. I would use 'vigr'
> > > > and 'vigr -s'.
> > >
> > > Near as I can tell, /etc/group- is simply a backup copy of /etc/group
> > > and shouldn't be edited. You might be thinking of /etc/gshadow, which
> > > has something to do with group passwords, which are a thing I have *never*
> > > dealt with in my entire life.
> >
> > I also forgot: after carrying out the corrected procedure, log out and
> > log back in.
_DON'T_ edit groups / shadow password files by hand unless really, absolutely
necessary - the potential for mistakes is too high.
adduser [username] lpadmin as root/root equivalent using sudo is all that's
needed.
You don't need to reboot to do this: but you might need to log out/log back
in to pick up the added/changed groups for the user.
>
> This is the part that I don't quite understand. How does that matter?
> Does the CUPS daemon connect to some already-running process of the
> user that you log into the web agent with? Does that mean you have to
> run the web browser *as* the user you plan to use for printer admin, not
> just log into the CUPS web agent with that user?
>
> That doesn't sound right, given the fact that you can log into the web
> agent as "root" without logging into Linux as root, or running the web
> browser as root.
>
> Given the above, I'd expect that the web agent spawns a brand new process
> as root, and then inside of that, it drops privileges down to the user
> that you specified.
>
> Unless "root" is a special hard-coded exception somehow...?
>
All best, as ever,
Andy Cater
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