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From: James Morris <jmorris@namei.org>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Mimi Zohar <zohar@linux.vnet.ibm.com>,
	linux-integrity@vger.kernel.org,
	linux-security-module@vger.kernel.org,
	linux-kernel@vger.kernel.org, David Howells <dhowells@redhat.com>,
	"Luis R . Rodriguez" <mcgrof@kernel.org>,
	kexec@lists.infradead.org, Andres Rodriguez <andresx7@gmail.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Ard Biesheuvel <ard.biesheuvel@linaro.org>,
	Kees Cook <keescook@chromium.org>,
	Casey Schaufler <casey@schaufler-ca.com>
Subject: Re: [PATCH v3 1/7] security: rename security_kernel_read_file() hook
Date: Wed, 30 May 2018 06:32:16 +1000 (AEST)	[thread overview]
Message-ID: <alpine.LRH.2.21.1805300629220.2647@namei.org> (raw)
In-Reply-To: <871sdzy0nv.fsf@xmission.com>

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

> James Morris <jmorris@namei.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@namei.org>


  reply	other threads:[~2018-05-29 20:32 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-24 11:09 [PATCH v3 0/7] kexec/firmware: support system wide policy requiring signatures Mimi Zohar
2018-05-24 11:09 ` [PATCH v3 1/7] security: rename security_kernel_read_file() hook Mimi Zohar
2018-05-24 20:49   ` Eric W. Biederman
2018-05-24 23:29     ` Mimi Zohar
2018-05-25 12:22     ` Mimi Zohar
2018-05-25 15:41     ` James Morris
2018-05-25 19:51       ` Eric W. Biederman
2018-05-29 20:32         ` James Morris [this message]
2018-05-29 21:10           ` Eric W. Biederman
2018-05-24 11:09 ` [PATCH v3 2/7] kexec: add call to LSM hook in original kexec_load syscall Mimi Zohar
2018-05-24 20:50   ` Eric W. Biederman
2018-05-24 11:09 ` [PATCH v3 3/7] ima: based on policy require signed kexec kernel images Mimi Zohar
2018-05-24 11:09 ` [PATCH v3 4/7] firmware: add call to LSM hook before firmware sysfs fallback Mimi Zohar
2018-05-24 11:09 ` [PATCH v3 5/7] ima: based on policy require signed firmware (sysfs fallback) Mimi Zohar
2018-05-24 11:09 ` [PATCH v3 6/7] ima: add build time policy Mimi Zohar
2018-05-24 11:09 ` [RFC PATCH v3 7/7] ima: based on policy prevent loading firmware (pre-allocated buffer) Mimi Zohar

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