[CentOS] SELinux and access across 'similar types'

Les Mikesell lesmikesell at gmail.com
Wed Jan 11 21:04:04 UTC 2012

2012/1/11 夜神 岩男 <supergiantpotato at yahoo.co.jp>:
>> Yes, the breakage came from having someone who didn't understand the
>> needs define that policy.
> I think you are misunderstanding how SELinux policies are formed and how
> they work. Its a *lot* less complicated and mysterious than you're
> making it sound. For most applications its really, really easy to do this.

You still haven't quantified this yet so I can understand what you
consider 'really, really easy'.  How many Fedora bugs have there been
specifically related to this?

>> So if an application only needs to do something once at some future
>> time, what happens?  If you write an application that will need to do
>> something at some rare future time, what is the standard way to tell
>> distribution packaging systems and system administrators to permit it?
> I'm trying to think of a single example (that isn't a worm) that fits
> this description.
> Can you think of any examples? (again, worms don't count... actually,
> that is sort of the point here...)

For an obvious case, consider an application that needs to send mail
but only does it when certain errors happen.  Or an application that
is configured to fail over using different ports/addresses/sockets
that won't be used until the primary fails and may never be seen in an
attempt to guess what is supposed to be happening.  Or distributed
applications that negotiate connections.  What about something like
the remote monitoring instances that OpenNMS can instantiate with
java's RMI capabilities?

> No, there are tools that do almost all the work for you. Its much easier
> than learning how to write a spec file in the first place. At this point
> it sounds like you're just arguing against something you're refusing to
> find out more about

No, I'm arguing that I don't know how to exchange this information in
a useful way. And that I don't believe reverse-engineering is the best
approach to it.  Assuming I would write a new application, how would I
confer the knowledge about the needed policy to the places where it
needs to be enacted.   You can even take distributions out of the
context of this question.  If a local development group is
building/changing applications, what is the expected way for them to
inform the system administrators or the operators that will be
installing it about the policy needs?

-- which is the standard human policy towards
> SELinux, so you're in good company (it used to be the standard human
> policy toward ipchains back in the day, too).

No, it is the standard human policy when policy makers try to impose
policy in ways that don't make sense.

>You can just turn it off if it bothers you so much.

That kind of misses the point.  You could run everything as root if
you wanted and make all your files mode 777.  The reason people don't
is that application programs have ways to use lower privileges and
ways to represent what is needed.   For other restrictions to be
widely usable you need standard ways to represent what is required and
exchange that information.

    Les Mikesell
      lesmikesell at gmail.com

More information about the CentOS mailing list