[selinux] Re: Right way to do CGI that does complicated things?

[Robin Lee Powell]

OK, read that (again :), played around a bit.  According to "sudo
sesearch -T -t sendmail_exec_t":

  type_transition httpd_sys_script_t sendmail_exec_t : process system_mail_t;

but there's no similar one for any of the other httpd script
transitions.  I suppose I should try marking it with
httpd_sys_script_t and see how it goes.

-Robin

On Fri, Sep 02, 2011 at 01:50:13PM -1000, Jason Axelson wrote:
> Hi Robin,
> 
> I can't really answer your questions about what you should do, but
> I wanted to provide a link that shows why httpd_user_script_t is
> not transitioning to sendmail_t.
> 
> http://danwalsh.livejournal.com/23944.html
> 
> Jason
> 
> On Fri, Sep 2, 2011 at 1:33 PM, Robin Lee Powell
> <rlpowell at digitalkingdom.org> wrote:
> >
> > (Background: My SELinux hosts are all F15, fairly base installation,
> > with the unconfined module disabled)
> >
> > I have a host that is for random hackery, and hence is (or at least
> > is allowed to be) less secure than the others.
> >
> > I have a user who made a CGI (running under apache; python, in case
> > that matters) that pulls things from elsewhere on the web and then
> > sends email with the results.
> >
> > This generates a pretty large number of AVC denials, which I suppose
> > is reasonable since that behaviour looks an awful lot like "I just
> > got hijacked and am now being used for spam distribution".
> >
> > One thing I was genuinely surprised by though is that the
> > mail-related denials all came in for httpd_user_script_t , rather
> > than sendmail_t or something, and that no attempt to transition to
> > sendmail_t seems to have occured or been denied or anything, as I'd
> > have expected (it sends mail with /bin/mail ).
> >
> > FWIW, here's the AVCs:
> >
> > http://fpaste.org/ZyHg/  (uses date from the input form only)
> >
> > http://fpaste.org/M9Fq/  (goes out and talks to another website)
> >
> > I've learned a lot about SELinux recently, but it's all been
> > piecemeal, so this is more of a "what's the right thing?" question
> > designed to for me to learn from more than "what's the fastest way
> > to fix this?".
> >
> > So, what's the right way to handle this situation?
> >
> > httpd_user_script_exec_t doesn't do the trick at all (which is
> > probably good since it turns out user_u can set that with chcon,
> > which I didn't expect).
> >
> > Is there some way without installing a module (i.e. with semanage or
> > similar) to indicate to SELinux "Yeah, this script over here?  It
> > can talk to the web" (or "send email")?
> >
> > Is there a way to indicate that system-wide without installing a
> > module?  (not that I would, just curious)
> >
> > If doing it via module, it's best to create a bobs_script_exec_t and
> > bobs_script_t and do everything for those types, rather than
> > httpd_user_script_exec_t and friends, right?  This means that a user
> > making a non-trivial CGI has to come talk to me, which is a tad
> > unfortunate but not horrible.
> >
> > Thanks for all enlightenment here, and please feel free to go the
> > "you're thinking about it wrong" route; I'm really wanting to learn.
> >
> > -Robin
> >
> > --
> > http://singinst.org/ :  Our last, best hope for a fantastic future.
> > Lojban (http://www.lojban.org/): The language in which "this parrot
> > is dead" is "ti poi spitaki cu morsi", but "this sentence is false"
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> >
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-- 
http://singinst.org/ :  Our last, best hope for a fantastic future.
Lojban (http://www.lojban.org/): The language in which "this parrot
is dead" is "ti poi spitaki cu morsi", but "this sentence is false"
is "na nei".   My personal page: http://www.digitalkingdom.org/rlp/