Message-ID: <4C1C2A07.8020007@schaufler-ca.com>
Date: Fri, 18 Jun 2010 19:23:03 -0700
From: Casey Schaufler <casey@schaufler-ca.com>
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To: "Eric W. Biederman" <ebiederm@xmission.com>
CC: Theodore Tso <tytso@MIT.EDU>, Alan Cox <alan@lxorguk.ukuu.org.uk>,
       Kees Cook <kees.cook@canonical.com>,
       Randy Dunlap <rdunlap@xenotime.net>, James Morris <jmorris@namei.org>,
       linux-kernel@vger.kernel.org, Andrew Morton <akpm@linux-foundation.org>,
       Jiri Kosina <jkosina@suse.cz>, Dave Young <hidave.darkstar@gmail.com>,
       Martin Schwidefsky <schwidefsky@de.ibm.com>,
       Roland McGrath <roland@redhat.com>, Oleg Nesterov <oleg@redhat.com>,
       "H. Peter Anvin" <hpa@zytor.com>, David Howells <dhowells@redhat.com>,
       Ingo Molnar <mingo@elte.hu>, Peter Zijlstra <a.p.zijlstra@chello.nl>,
       linux-doc@vger.kernel.org, Stephen Smalley <sds@tycho.nsa.gov>,
       Daniel J Walsh <dwalsh@redhat.com>,
       linux-security-module@vger.kernel.org
Subject: Re: [PATCH] ptrace: allow restriction of ptrace scope
References: <20100616221833.GM24749@outflux.net>	<20100617000120.13071be8@lxorguk.ukuu.org.uk>	<20100616232230.GP24749@outflux.net>	<alpine.LRH.2.00.1006172336390.17282@tundra.namei.org>	<20100617170453.GV24749@outflux.net>	<20100617215349.2fac02f5@lxorguk.ukuu.org.uk>	<20100617140630.c6ced27a.rdunlap@xenotime.net>	<20100617221815.68ce30c5@lxorguk.ukuu.org.uk>	<20100617215105.GB24749@outflux.net>	<20100617233054.330256cf@lxorguk.ukuu.org.uk>	<4C1AE3A8.2020104@schaufler-ca.com>	<E1FEE555-566E-4698-8FD8-240076A4F850@mit.edu> <m1wrtwwiua.fsf@fess.ebiederm.org>
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Eric W. Biederman wrote:
> Theodore Tso <tytso@MIT.EDU> writes:
>
>   
>> i think we really need to have stacked LSM's,

!

>>  because there is a large set
>> of people who will never use SELinux.  Every few years, I take another 
>> look at SELinux, my head explodes with the (IMHO unneeded complexity),
>> and I go away again...
>>
>> Yet I would really like a number of features such as this ptrace scope idea ---
>> which I think is a useful feature, and it may be that stacking is the only
>> way we can resolve this debate.   The SELinux people will never believe that
>> their system is too complicated, and I don't like using things that are impossible
>> for me to understand or configure, and that doesn't seem likely to change anytime
>> in the near future.
>>
>> I mean, even IPSEC RFC's are easier for me to understand, and that's saying
>> a lot...
>>     
>
>
> If anyone is going to work on this let me make a concrete suggestion.
> Let's aim at not stacked lsm's but chained lsm's, and put the chaining
> logic in the lsm core.
>   

It's 35 years since my data structures course. What's the important
difference between the two?

> The core difficulty appears to be how do you multiplex the security pointers
> on various objects out there.
>   

That and making sure that the hooks that maintain state get called
even if the decision to deny access has already been made by someone
else.

> My wishlist has this working so that I can logically have a local security
> policy in a container, restricted by the global policy but with additional
> restrictions.
>
> Eric
> --
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>   

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