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Subject: Re: [PATCH v2 5/8] ima: Switch to dynamically allocated buffer for
 template digests
From:   Mimi Zohar <zohar@linux.ibm.com>
To:     Roberto Sassu <roberto.sassu@huawei.com>,
        James.Bottomley@HansenPartnership.com,
        jarkko.sakkinen@linux.intel.com
Cc:     linux-integrity@vger.kernel.org,
        linux-security-module@vger.kernel.org,
        linux-kernel@vger.kernel.org, silviu.vlasceanu@huawei.com
Date:   Thu, 06 Feb 2020 11:08:04 -0500
In-Reply-To: <20200205103317.29356-6-roberto.sassu@huawei.com>
References: <20200205103317.29356-1-roberto.sassu@huawei.com>
         <20200205103317.29356-6-roberto.sassu@huawei.com>
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Hi Roberto,

On Wed, 2020-02-05 at 11:33 +0100, Roberto Sassu wrote:
> This patch dynamically allocates the array of tpm_digest structures in
> ima_alloc_init_template() and ima_restore_template_data(). The size of the
> array, stored in ima_num_template_digests, is initially equal to 1 (SHA1)
> and will be determined in the upcoming patches depending on the allocated
> PCR banks and the chosen default IMA algorithm.
> 
> Calculating the SHA1 digest is mandatory, as SHA1 still remains the default
> hash algorithm for the measurement list. When IMA will support the Crypto
> Agile format, remaining digests will be also provided.
> 
> The position in the array of the SHA1 digest is stored in the ima_sha1_idx
> global variable and it is determined at IMA initialization time.
> 
> Changelog
> 
> v1:
> - move ima_sha1_idx to ima_crypto.c
> - introduce ima_num_template_digests (suggested by Mimi)

Instead of hardcoding "nr_allocated_banks + 1" or nr_allocated_banks +
2", I suggested defining "nr_allocated_banks + extra", where "extra"
could be 0, 1, or 2.

The rest of the code would remain exactly the same as you had.

Mimi