linux-kernel - Re: [PATCH v3 1/7] security: rename security_kernel_read

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Message-ID: <alpine.LRH.2.21.1805300629220.2647@namei.org>
Date:   Wed, 30 May 2018 06:32:16 +1000 (AEST)
From:   James Morris <jmorris@...ei.org>
To:     "Eric W. Biederman" <ebiederm@...ssion.com>
cc:     Mimi Zohar <zohar@...ux.vnet.ibm.com>,
        linux-integrity@...r.kernel.org,
        linux-security-module@...r.kernel.org,
        linux-kernel@...r.kernel.org, David Howells <dhowells@...hat.com>,
        "Luis R . Rodriguez" <mcgrof@...nel.org>,
        kexec@...ts.infradead.org, Andres Rodriguez <andresx7@...il.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Kees Cook <keescook@...omium.org>,
        Casey Schaufler <casey@...aufler-ca.com>
Subject: Re: [PATCH v3 1/7] security: rename security_kernel_read_file()
 hook

On Fri, 25 May 2018, Eric W. Biederman wrote:

> James Morris <jmorris@...ei.org> writes:
> 
> > On Thu, 24 May 2018, Eric W. Biederman wrote:
> >
> >> Below is where I suggest you start on sorting out these security hooks.
> >> - Adding a security_kernel_arg to catch when you want to allow/deny the
> >>   use of an argument to a syscall.  What security_kernel_file_read and
> >>   security_kernel_file_post_read have been abused for.
> >
> > NAK. This abstraction is too semantically weak.
> >
> > LSM hooks need to map to stronger semantics so we can reason about what 
> > the hook and the policy is supposed to be mediating.
> 
> I will take that as an extremely weak nack as all I did was expose the
> existing code and what the code is currently doing.  I don't see how you
> can NAK what is already being merged and used.

It's a strong NAK.

LSM is a logical API, it provides an abstraction layer for security 
policies to mediate kernel security behaviors.

Adding an argument to a syscall is not a security behavior.

Loading a firmware file is.

=
-- 
James Morris
<jmorris@...ei.org>