linux-kernel - Re: [PATCH 6/6] ima: Support appended signatures for appraisal

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Message-Id: <1565385.DQpqeaisNG@morokweng>
Date:   Thu, 27 Apr 2017 18:41:35 -0300
From:   Thiago Jung Bauermann <bauerman@...ux.vnet.ibm.com>
To:     Mehmet Kayaalp <mkayaalp@...ux.vnet.ibm.com>
Cc:     kbuild test robot <lkp@...el.com>, kbuild-all@...org,
        LSM <linux-security-module@...r.kernel.org>,
        linux-ima-devel@...ts.sourceforge.net,
        keyrings <keyrings@...r.kernel.org>,
        linux-crypto@...r.kernel.org,
        kernel <linux-kernel@...r.kernel.org>,
        Mimi Zohar <zohar@...ux.vnet.ibm.com>,
        Dmitry Kasatkin <dmitry.kasatkin@...il.com>,
        David Howells <dhowells@...hat.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "David S. Miller" <davem@...emloft.net>,
        Claudio Carvalho <cclaudio@...ux.vnet.ibm.com>
Subject: Re: [PATCH 6/6] ima: Support appended signatures for appraisal

Am Mittwoch, 26. April 2017, 18:18:34 BRT schrieb Mehmet Kayaalp:
> > On Apr 20, 2017, at 7:41 PM, Thiago Jung Bauermann
> > <bauerman@...ux.vnet.ibm.com> wrote:
> > 
> > This patch introduces the appended_imasig keyword to the IMA policy syntax
> > to specify that a given hook should expect the file to have the IMA
> > signature appended to it. Here is how it can be used in a rule:
> > 
> > appraise func=KEXEC_KERNEL_CHECK appraise_type=appended_imasig
> > appraise func=KEXEC_KERNEL_CHECK appraise_type=appended_imasig|imasig
> > 
> > In the second form, IMA will accept either an appended signature or a
> > signature stored in the extended attribute. In that case, it will first
> > check whether there is an appended signature, and if not it will read it
> > from the extended attribute.
> > 
> > The format of the appended signature is the same used for signed kernel
> > modules. This means that the file can be signed with the scripts/sign-file
> 
> > tool, with a command line such as this:
> I would suggest naming the appraise_type as modsig (or some variant) to
> clarify that the format is defined by how module signatures are handled.
> Maybe we'd like to define a different appended/inline signature format for
> IMA in the future.

I like the suggestion. Would that mean that we will keep refering to it as 
"module signature format", and thus nothing changes in patch 5?

-- 
Thiago Jung Bauermann
IBM Linux Technology Center