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Re: A little daemon



On Thu, Oct 17, 2002 at 05:37:18PM +0200, Raffaele Sandrini wrote:
> On Thursday 17 October 2002 15:11, Andrew Perrin wrote:
> > It's a bad idea :)
> >
> > No, really - what do you need to do that can't be done by sudo, cron, or
> > at?  These are well-tested tools and will probably make you happier than
> > your plan.

[snip]

> > Let me reiterate, though: it's a BAD IDEA. How will you make sure nobody
> > has access to running root scripts through your daemon?
> 
> hehe, I thought your answer may result like that :-))
> 
> I need it for a small KDE application wich needs to execute some privileged 
> procecesses (like mount) WITHOUT password promting to the user. The KDE app 
> itself can't run as root (casue that needs an extra enviroment and i don't 
> want that) and setuid root is not a good idea cause of the kdelibs (and also 
> here a root env would be necessary).

IMHO a better way would be:

- Create a script in /usr/local/bin that does whatever you need it to.
  Make sure it works when root executes it - doesn't have to work for
  mere mortals.

- Add a line to /etc/sudoers that allows user X to execute that script
  as root *without* having to supply a password:
        <usernameX> <hostname> = NOPASSWD: /usr/local/bin/yourscript

Make sure that there aren't any "holes" in your script:
    - Avoid command line parameters if possible
    - Early in the script set the PATH and IFS variables to known values
    - Dont use e.g. "#!/usr/bin/env interpreter", but go straight to
      "#!/usr/bin/interpreter"

And educate user X about the dangers and enforce any rules you lay down:
cracking user X's account will now allow the black hats to execute
/usr/local/bin/yourscript as root...

As far as I can see, this would satisfy your needs - but be sure that
you understand the security implications.

HTH

-- 
Karl E. Jørgensen
karl@jorgensen.com
www.karl.jorgensen.com
==== Today's fortune:
Linux: the choice of a GNU generation
	-- ksh@cis.ufl.edu put this on Tshirts in '93

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