linux-kernel - Re: [PATCH v2 0/3] initramfs: add support for xattrs in the initial ram disk

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Message-ID: <3723FF4B-FD47-47AE-A22B-A09C841C192B@zytor.com>
Date:   Sun, 12 May 2019 17:21:17 -0700
From:   hpa@...or.com
To:     Mimi Zohar <zohar@...ux.ibm.com>,
        Dominik Brodowski <linux@...inikbrodowski.net>
CC:     Roberto Sassu <roberto.sassu@...wei.com>, viro@...iv.linux.org.uk,
        linux-security-module@...r.kernel.org,
        linux-integrity@...r.kernel.org, initramfs@...r.kernel.org,
        linux-api@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org, zohar@...ux.vnet.ibm.com,
        silviu.vlasceanu@...wei.com, dmitry.kasatkin@...wei.com,
        takondra@...co.com, kamensky@...co.com, arnd@...db.de,
        rob@...dley.net, james.w.mcmechan@...il.com
Subject: Re: [PATCH v2 0/3] initramfs: add support for xattrs in the initial ram disk

On May 12, 2019 5:02:30 PM PDT, Mimi Zohar <zohar@...ux.ibm.com> wrote:
>On Sun, 2019-05-12 at 17:31 +0200, Dominik Brodowski wrote:
>> On Sun, May 12, 2019 at 08:52:47AM -0400, Mimi Zohar wrote:
>
>
>> > It's too late.  The /init itself should be signed and verified.
>> 
>> Could you elaborate a bit more about the threat model, and why
>deferring
>> this to the initramfs is too late?
>
>The IMA policy defines a number of different methods of identifying
>which files to measure, appraise, audit.[1]  Without xattrs, the
>granularity of the policy rules is severely limited.  Without xattrs,
>a filesystem is either in policy, or not.
>
>With an IMA policy rule requiring rootfs (tmpfs) files to be verified,
>then /init needs to be properly labeled, otherwise /init will fail to
>execute.
>
>Mimi
>
>[1] Documentation/ABI/testing/ima_policy

And the question is what is the sense in that, especially if /init is provided as play of the kernel itself.
-- 
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