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From: Mimi Zohar <zohar@linux.ibm.com>
To: Roberto Sassu <roberto.sassu@huawei.com>,
	jarkko.sakkinen@linux.intel.com,
	james.bottomley@hansenpartnership.com,
	linux-integrity@vger.kernel.org
Cc: linux-security-module@vger.kernel.org,
	linux-kernel@vger.kernel.org, silviu.vlasceanu@huawei.com
Subject: Re: [PATCH 5/8] ima: allocate and initialize tfm for each PCR bank
Date: Fri, 31 Jan 2020 07:18:53 -0500
Message-ID: <1580473133.6104.48.camel@linux.ibm.com> (raw)
In-Reply-To: <20200127170443.21538-6-roberto.sassu@huawei.com>

On Mon, 2020-01-27 at 18:04 +0100, Roberto Sassu wrote:
> This patch creates a crypto_shash structure for each allocated PCR bank and
> for SHA1 if a bank with that algorithm is not currently allocated.
> 
> Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>

<snip>

> +int __init ima_init_crypto(void)
> +{
> +	enum hash_algo algo;
> +	long rc;
> +	int i;
> +
> +	rc = ima_init_ima_crypto();
> +	if (rc)
> +		return rc;
> +
> +	ima_algo_array = kmalloc_array(ima_tpm_chip->nr_allocated_banks + 1,
> +				       sizeof(*ima_algo_array), GFP_KERNEL);

Perhaps instead of hard coding "nr_allocated_banks + 1", create a
variable for storing the number of "extra" banks.  Walk the banks
setting ima_sha1_idx and, later, in a subsequent patch set
ima_hash_algo_idx.

> +	if (!ima_algo_array) {
> +		rc = -ENOMEM;
> +		goto out;
> +	}
> +
> +	for (i = 0; i < ima_tpm_chip->nr_allocated_banks + 1; i++) {
> +		ima_algo_array[i].tfm = NULL;
> +		ima_algo_array[i].algo = HASH_ALGO__LAST;
> +	}

ima_init_crypto() is executed once on initialization.  I'm not sure if
it makes a difference, but if you're really concerned about an
additional loop, the initialization, here, could be limited to the
"extra" banks.  The other banks could be initialized at the beginning
of the next loop.

thanks,

Mimi

> +	ima_sha1_idx = -1;
> +
> +	for (i = 0; i < ima_tpm_chip->nr_allocated_banks; i++) {
> +		algo = ima_tpm_chip->allocated_banks[i].crypto_id;
> +		ima_algo_array[i].algo = algo;
> +
> +		/* unknown TPM algorithm */
> +		if (algo == HASH_ALGO__LAST)
> +			continue;
> +
> +		if (algo == HASH_ALGO_SHA1)
> +			ima_sha1_idx = i;
> +
> +		if (algo == ima_hash_algo) {
> +			ima_algo_array[i].tfm = ima_shash_tfm;
> +			continue;
> +		}
> +
> +		ima_algo_array[i].tfm = ima_alloc_tfm(algo);
> +		if (IS_ERR(ima_algo_array[i].tfm)) {
> +			if (algo == HASH_ALGO_SHA1) {
> +				rc = PTR_ERR(ima_algo_array[i].tfm);
> +				ima_algo_array[i].tfm = NULL;
> +				goto out_array;
> +			}
> +
> +			ima_algo_array[i].tfm = NULL;
> +		}
> +	}
> +
> +	if (ima_sha1_idx < 0) {
> +		ima_algo_array[i].tfm = ima_alloc_tfm(HASH_ALGO_SHA1);
> +		if (IS_ERR(ima_algo_array[i].tfm)) {
> +			rc = PTR_ERR(ima_algo_array[i].tfm);
> +			goto out_array;
> +		}
> +
> +		ima_sha1_idx = i;
> +		ima_algo_array[i].algo = HASH_ALGO_SHA1;
> +	}
> +
> +	return 0;
> +out_array:
> +	for (i = 0; i < ima_tpm_chip->nr_allocated_banks + 1; i++) {
> +		if (!ima_algo_array[i].tfm ||
> +		    ima_algo_array[i].tfm == ima_shash_tfm)
> +			continue;
> +
> +		crypto_free_shash(ima_algo_array[i].tfm);
> +	}
> +out:
> +	crypto_free_shash(ima_shash_tfm);
> +	return rc;
> +}


  reply index

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-27 17:04 [PATCH 0/8] ima: support stronger algorithms for attestation Roberto Sassu
2020-01-27 17:04 ` [PATCH 1/8] tpm: initialize crypto_id of allocated_banks to HASH_ALGO__LAST Roberto Sassu
2020-01-29  8:39   ` Petr Vorel
2020-01-30  8:47   ` Jarkko Sakkinen
2020-01-30 16:11     ` Roberto Sassu
2020-01-31 13:33       ` Mimi Zohar
2020-02-01 17:10         ` Jarkko Sakkinen
2020-01-27 17:04 ` [PATCH 2/8] ima: evaluate error in init_ima() Roberto Sassu
2020-01-31 13:33   ` Mimi Zohar
2020-01-27 17:04 ` [PATCH 3/8] ima: store template digest directly in ima_template_entry Roberto Sassu
2020-01-27 17:04 ` [PATCH 4/8] ima: switch to dynamically allocated buffer for template digests Roberto Sassu
2020-01-27 17:04 ` [PATCH 5/8] ima: allocate and initialize tfm for each PCR bank Roberto Sassu
2020-01-31 12:18   ` Mimi Zohar [this message]
2020-01-31 13:42     ` Roberto Sassu
2020-01-31 13:58       ` Mimi Zohar
2020-01-27 17:04 ` [PATCH 6/8] ima: calculate and extend PCR with digests in ima_template_entry Roberto Sassu
2020-01-27 17:29   ` Roberto Sassu
2020-01-27 17:04 ` [PATCH 7/8] ima: use ima_hash_algo for collision detection in the measurement list Roberto Sassu
2020-01-30 22:26   ` Mimi Zohar
2020-01-31 14:02     ` Roberto Sassu
2020-01-31 14:22       ` Mimi Zohar
2020-01-31 14:41         ` Roberto Sassu
2020-01-31 14:50           ` Mimi Zohar
2020-01-27 17:04 ` [PATCH 8/8] ima: switch to ima_hash_algo for boot aggregate Roberto Sassu
2020-01-31 15:21   ` Roberto Sassu
2020-01-30 22:26 ` [PATCH 0/8] ima: support stronger algorithms for attestation Mimi Zohar

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