Re: [PATCH v12 0/9] LSM: Multiple concurrent LSMs

John Johansen
2013-01-08T20:40:51Z

On 01/08/2013 01:12 AM, James Morris wrote:
> On Mon, 7 Jan 2013, Casey Schaufler wrote:
>
>> There has been an amazing amount of development in system security
>> over the past three years. Almost none of it has been in the kernel.
>> One important reason that it is not getting done in the kernel is
>> that the current single LSM restriction requires an all or nothing
>> approach to security. Either you address all your needs with a single
>> LSM or you have to go with a user space solution, in which case you
>> may as well do everything in user space.
>
> This sounds like a very spurious argument. If the development is better
> done in userspace, then do it there.
>
> There's no way to address all your security needs with an LSM in any case,
> for any practical system. LSM is an API for making security decisions
> about kernel flow, usually as part of implementing access control
> mechanisms. It is not meant to provide any kind of total security
> solution, and the argument that you can't do some security in userspace is
> totally illogical.
>
> Development should be done in userspace unless it must be done in the
> kernel.
>
>> Multiple concurrent LSMs allows a system to be developed incrementally
>> and to combine a variety of approaches that meet new and interesting
>> needs. It allows for systems that are based on an LSM that does not
>> meet all of the requirements but that can be supplemented by another
>> LSM that fills the gaps. It allows an LSM like Smack that implements
>> label based access controls to remain true to its purpose even in the
>> face of pressure to add controls based on other mechanisms.
>>
>> I have had requests for running Smack and AppArmor together Tetsuo has
>> long had need to put SELinux and TOMOYO on the same box. Yama was
>> recently special cased for stackability.
>
> I'd say we need to see the actual use-case for Smack and Apparmor being
> used together, along with at least one major distro committing to support
> this.
>
>
Ubuntu is very interested in stacking