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From Randy Terbush <>
Subject Re: setuid() again
Date Mon, 01 Jan 1996 15:19:56 GMT
> > I've explored the following suggestions:
> > 
> > * setuid to the user of the CGI script
> > 
> >    This method creates many support headaches.
> > 	. users not understanding how to setuid a script
> > 	. perl not wanting to exec a setuid script
> > 	. ease of creating a wrapper for every user's CGI script
> > 
> > * cgiwrapper
> > 
> >    Disables the ability to have index.cgi
> So fix it.

'cgiwrapper' is not really designed with this in mind. My 'fix'
is what I propose.

> >    Some support issues with explaining it's use.
> And integrate its use tightly into Apache.

Which is what the seteuid() stuff does.

> > This brings me back to the use of seteuid() in the server.
> > 
> > While I agree that it is somewhat scary to be switching uids
> > in our CGI code, there are benefits to this approach that 
> > *improve* security as well. Correct me if I'm wrong...
> > (as if I need to ask)
> > 
> > Most changes can be restricted to can_exec().
> > 
> > We can:
> > 	disallow execution of any CGI by uid 0.
> You should disallow all serving of anything by uid 0.

Which is done.

> > 	force the CGI script to be under the owners home directory
> OK, but why? If they want to run a script outside their home dir, they just
> write a script in their home dir saying:
> /some/where/else/script

The solution would probably be to run in a chroot()ed environment.

> > 	restrict system resources on OSs with setrlimit
> And what of those without setrlimit?

You lose.

> > It seems that after all of these conditions have been met,
> > seteuid() to the owner of the script is relatively safe.
> Ahem.
> Apart from the danger of processing the request as root, and the objections
> above, totally safe.

You are not processing the request as root. The server does a seteuid(0),
immediately followed by a seteuid("owner of script"), processes the request
as the owner of the script, and  then returns to being "nobody" or whomever
you have chosen to run as.

If we are really concerned about the security of Apache, then we should
be doing more than a seteuid() to user_id in http_main.c.

I am more confident in the security of Apache than sendmail. I still
run sendmail. Have the rest of you disabled root daemons on your systems?

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