linux-kernel - Re: [PATCH 2/3] binfmt_elf: Verify signature of signed elf binary

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Message-ID: <1358375723.4593.206.camel@falcor1>
Date:	Wed, 16 Jan 2013 17:35:23 -0500
From:	Mimi Zohar <zohar@...ux.vnet.ibm.com>
To:	Vivek Goyal <vgoyal@...hat.com>
Cc:	linux-kernel@...r.kernel.org, ebiederm@...ssion.com,
	pjones@...hat.com, hpa@...or.com, dhowells@...hat.com,
	jwboyer@...hat.com, Dmitry Kasatkin <dmitry.kasatkin@...el.com>,
	linux-security-module <linux-security-module@...r.kernel.org>
Subject: Re: [PATCH 2/3] binfmt_elf: Verify signature of signed elf binary

On Tue, 2013-01-15 at 16:34 -0500, Vivek Goyal wrote:
> If a binary is signed, verify its signature. If signature is not valid, do
> not allow execution. If binary is not signed, execution is allowed
> unconditionally.

Basically you're building the policy into the executable.  Anyone can
rebuild the executable and, without signing it, install/replace an
existing one.  How is this safe?  The signature verification policy
needs to be defined independently of the executable.

Mimi

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