linux-kernel - Re: [PATCH v4 1/7] ima: Switch to ima_hash

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Date:   Thu, 02 Apr 2020 19:53:37 -0400
From:   Mimi Zohar <zohar@...ux.ibm.com>
To:     Roberto Sassu <roberto.sassu@...wei.com>,
        James.Bottomley@...senPartnership.com,
        Jerry Snitselaar <jsnitsel@...hat.com>
Cc:     linux-integrity@...r.kernel.org,
        linux-security-module@...r.kernel.org,
        linux-kernel@...r.kernel.org, silviu.vlasceanu@...wei.com,
        stable@...r.kernel.org
Subject: Re: [PATCH v4 1/7] ima: Switch to ima_hash_algo for boot aggregate

Hi Roberto,

On Wed, 2020-03-25 at 11:47 +0100, Roberto Sassu wrote:
> boot_aggregate is the first entry of IMA measurement list. Its purpose is
> to link pre-boot measurements to IMA measurements. As IMA was designed to
> work with a TPM 1.2, the SHA1 PCR bank was always selected even if a
> TPM 2.0 with support for stronger hash algorithms is available.
> 
> This patch first tries to find a PCR bank with the IMA default hash
> algorithm. If it does not find it, it selects the SHA256 PCR bank for
> TPM 2.0 and SHA1 for TPM 1.2. Ultimately, it selects SHA1 also for TPM 2.0
> if the SHA256 PCR bank is not found.
> 
> If none of the PCR banks above can be found, boot_aggregate file digest is
> filled with zeros, as for TPM bypass, making it impossible to perform a
> remote attestation of the system.
> 
> Cc: stable@...r.kernel.org # 5.1.x
> Fixes: 879b589210a9 ("tpm: retrieve digest size of unknown algorithms with PCR read")
> Reported-by: Jerry Snitselaar <jsnitsel@...hat.com>
> Suggested-by: James Bottomley <James.Bottomley@...senPartnership.com>
> Signed-off-by: Roberto Sassu <roberto.sassu@...wei.com>

Thank you!  This patch set is now queued in next-integrity-testing
during the open window.  Jerry, I assume this works for you.  Could we
get your tag?

thanks!

Mimi