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 7/8] ima: use ima_hash_algo for collision detection in the measurement list
Date: Thu, 30 Jan 2020 17:26:09 -0500 [thread overview]
Message-ID: <1580423169.6104.18.camel@linux.ibm.com> (raw)
In-Reply-To: <20200127170443.21538-8-roberto.sassu@huawei.com>
On Mon, 2020-01-27 at 18:04 +0100, Roberto Sassu wrote:
> Before calculating a digest for each PCR bank, collisions were detected
> with a SHA1 digest. This patch includes ima_hash_algo among the algorithms
> used to calculate the template digest and checks collisions on that digest.
>
> Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Definitely needed to protect against a sha1 collision attack.
<snip>
>
> diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c
> index ebaf0056735c..a9bb45de6db9 100644
> --- a/security/integrity/ima/ima_api.c
> +++ b/security/integrity/ima/ima_api.c
> @@ -51,7 +51,7 @@ int ima_alloc_init_template(struct ima_event_data *event_data,
> if (!*entry)
> return -ENOMEM;
>
> - (*entry)->digests = kcalloc(ima_tpm_chip->nr_allocated_banks + 1,
> + (*entry)->digests = kcalloc(ima_tpm_chip->nr_allocated_banks + 2,
> sizeof(*(*entry)->digests), GFP_NOFS);
> if (!(*entry)->digests) {
> result = -ENOMEM;
I would prefer not having to allocate and use "nr_allocated_banks + 1"
everywhere, but I understand the need for it. I'm not sure this patch
warrants allocating +2. Perhaps, if a TPM bank doesn't exist for the
IMA default hash algorithm, use a different algorithm or, worst case,
continue using the ima_sha1_idx.
Mimi
next prev parent reply other threads:[~2020-01-30 22:26 UTC|newest]
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
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 [this message]
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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