Re: [PATCH] LSM: ModPin LSM for module loading restrictions

From: Casey Schaufler
Date: Thu Oct 17 2013 - 13:26:55 EST


On 10/17/2013 1:02 AM, James Morris wrote:
> This seems like a regression in terms of separating mechanism and policy.
>
> We have several access control systems available (SELinux, at least) which
> can implement this functionality with existing mechanisms using dynamic
> policy.

They said the same thing about Smack.

The problem there is that you have to buy into the entirety of
SELinux to implement a small bit of behavior. You have to write
a policy that takes every aspect of system behavior into account
when all you care about is loading restrictions on modules.

If you want all of SELinux you still have to define your problem
in a subject/object model. That may be possible, but in this
case at least it certainly ain't obvious.

> I'm concerned about the long term architectural impact of a proliferation
> of arbitrary hard-coded security policies in the kernel. I don't
> understand the push in this direction, frankly.

The rationale is that lots of people doing little things is
likely to get us relevant security in a reasonable amount of time.
The existing LSMs reflect 20th century technologies and use cases.
They are fine for multi-user timesharing systems. We need to move
forward to support networked gaming, phones, tablets and toasters.

>
> On Fri, 20 Sep 2013, Kees Cook wrote:
>
>> ...
>> --
>> 1.7.9.5
>>
>>
>> --
>> Kees Cook
>> Chrome OS Security
>> --
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