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Message-ID: <1593122039.27152.412.camel@linux.ibm.com>
Subject: Re: [PATCH 06/12] ima: Fail rule parsing when the KEXEC_CMDLINE
 hook is combined with an invalid cond
From:   Mimi Zohar <zohar@linux.ibm.com>
To:     Tyler Hicks <tyhicks@linux.microsoft.com>,
        Dmitry Kasatkin <dmitry.kasatkin@gmail.com>
Cc:     James Morris <jmorris@namei.org>,
        "Serge E . Hallyn" <serge@hallyn.com>,
        Lakshmi Ramasubramanian <nramas@linux.microsoft.com>,
        Prakhar Srivastava <prsriva02@gmail.com>,
        linux-kernel@vger.kernel.org, linux-integrity@vger.kernel.org,
        linux-security-module@vger.kernel.org
Date:   Thu, 25 Jun 2020 17:53:59 -0400
In-Reply-To: <20200623003236.830149-7-tyhicks@linux.microsoft.com>
References: <20200623003236.830149-1-tyhicks@linux.microsoft.com>
         <20200623003236.830149-7-tyhicks@linux.microsoft.com>
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On Mon, 2020-06-22 at 19:32 -0500, Tyler Hicks wrote:
> The KEXEC_CMDLINE hook function only supports the pcr conditional. Make
> this clear at policy load so that IMA policy authors don't assume that
> other conditionals are supported.
> 
> Since KEXEC_CMDLINE's inception, ima_match_rules() has always returned
> true on any loaded KEXEC_CMDLINE rule without any consideration for
> other conditionals present in the rule. Make it clear that pcr is the
> only supported KEXEC_CMDLINE conditional by returning an error during
> policy load.
> 
> An example of why this is a problem can be explained with the following
> rule:
> 
>  dont_measure func=KEXEC_CMDLINE obj_type=foo_t
> 
> An IMA policy author would have assumed that rule is valid because the
> parser accepted it but the result was that measurements for all
> KEXEC_CMDLINE operations would be disabled.
> 
> Fixes: b0935123a183 ("IMA: Define a new hook to measure the kexec boot command line arguments")
> Signed-off-by: Tyler Hicks <tyhicks@linux.microsoft.com>

Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>