Re: [PATCH v3] ima_evm_utils: extended calc_bootaggr to PCRs 8 - 9

From: Bruno Meneguele <bmeneg@redhat.com>
To: Maurizio Drocco <maurizio.drocco@ibm.com>
Cc: Silviu.Vlasceanu@huawei.com, dmitry.kasatkin@gmail.com,
	jejb@linux.ibm.com, jmorris@namei.org,
	linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-security-module@vger.kernel.org,
	mdrocco@linux.vnet.ibm.com, roberto.sassu@huawei.com,
	serge@hallyn.com, stefanb@linux.ibm.com, zohar@linux.ibm.com
Subject: Re: [PATCH v3] ima_evm_utils: extended calc_bootaggr to PCRs 8 - 9
Date: Wed, 24 Jun 2020 18:50:11 -0300	[thread overview]
Message-ID: <20200624215011.GC2639@glitch> (raw)
In-Reply-To: <20200624213558.4265-1-maurizio.drocco@ibm.com>

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On Wed, Jun 24, 2020 at 05:35:58PM -0400, Maurizio Drocco wrote:
> From: Maurizio <maurizio.drocco@ibm.com>
> 
> cal_bootaggr should include PCRs 8-9 in non-SHA1 digests.
> 
> Signed-off-by: Maurizio Drocco <maurizio.drocco@ibm.com>
> ---
> Changelog:
> v3:
> - Fixed patch description
> v2:
> - Always include PCRs 8 & 9 to non-sha1 hashes
> v1:
> - Include non-zero PCRs 8 & 9 to boot aggregates
> 
>  src/evmctl.c | 15 +++++++++++++--
>  1 file changed, 13 insertions(+), 2 deletions(-)
> 
> diff --git a/src/evmctl.c b/src/evmctl.c
> index 1d065ce..46b7092 100644
> --- a/src/evmctl.c
> +++ b/src/evmctl.c
> @@ -1930,6 +1930,16 @@ static void calc_bootaggr(struct tpm_bank_info *bank)
>  		}
>  	}
>  
> +	if (strcmp(bank->algo_name, "sha1") != 0) {
> +		for (i = 8; i < 10; i++) {
> +			err = EVP_DigestUpdate(pctx, bank->pcr[i], bank->digest_size);
> +			if (!err) {
> +				log_err("EVP_DigestUpdate() failed\n");
> +				return;
> +			}
> +		}
> +	}
> +
>  	err = EVP_DigestFinal(pctx, bank->digest, &mdlen);
>  	if (!err) {
>  		log_err("EVP_DigestFinal() failed\n");
> @@ -1972,8 +1982,9 @@ static int append_bootaggr(char *bootaggr, struct tpm_bank_info *tpm_banks)
>  /*
>   * The IMA measurement list boot_aggregate is the link between the preboot
>   * event log and the IMA measurement list.  Read and calculate all the
> - * possible per TPM bank boot_aggregate digests based on the existing
> - * PCRs 0 - 7 to validate against the IMA boot_aggregate record.
> + * possible per TPM bank boot_aggregate digests based on the existing PCRs
> + * 0 - 9 to validate against the IMA boot_aggregate record. If the digest
> + * algorithm is SHA1, only PCRs 0 - 7 are considered to avoid ambiguity.
>   */
>  static int cmd_ima_bootaggr(struct command *cmd)
>  {
> -- 
> 2.17.1
> 

Reviewed-by: Bruno Meneguele <bmeneg@redhat.com>

Thanks.

-- 
bmeneg 
PGP Key: http://bmeneg.com/pubkey.txt

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