linux-kernel - Re: [PATCH v3 02/11] evm: Load EVM key in ima_load

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Date:   Wed, 02 Dec 2020 12:27:34 -0500
From:   Mimi Zohar <zohar@...ux.ibm.com>
To:     Roberto Sassu <roberto.sassu@...wei.com>, mjg59@...gle.com
Cc:     linux-integrity@...r.kernel.org,
        linux-security-module@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        silviu.vlasceanu@...wei.com
Subject: Re: [PATCH v3 02/11] evm: Load EVM key in ima_load_x509() to avoid
 appraisal

On Wed, 2020-11-11 at 10:22 +0100, Roberto Sassu wrote:
> Public keys do not need to be appraised by IMA as the restriction on the
> IMA/EVM keyrings ensures that a key can be loaded only if it is signed with
> a key in the primary or secondary keyring.

Let's clean this up a bit.
- The public builtin keys ...
- IMA/EVM trusted keyrings ...
- on the builtin or secondary keyrings

> However, when evm_load_x509() is called, appraisal is already enabled and
> a valid IMA signature must be added to the EVM key to pass verification.
> 
> Since the restriction is applied on both IMA and EVM keyrings, it is safe

and update:
- IMA and EVM trusted keyrings 

> to disable appraisal also when the EVM key is loaded. This patch calls
> evm_load_x509() inside ima_load_x509() if CONFIG_IMA_LOAD_X509 is defined.

, which crosses the normal IMA and EVM boundary,

thanks,

Mimi