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From:   Maurizio Drocco <maurizio.drocco@ibm.com>
To:     stefanb@linux.ibm.com
Cc:     Silviu.Vlasceanu@huawei.com, bmeneg@redhat.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, maurizio.drocco@ibm.com,
        mdrocco@linux.vnet.ibm.com, roberto.sassu@huawei.com,
        serge@hallyn.com, zohar@linux.ibm.com
Subject: [PATCH] ima_evm_utils: extended calc_bootaggr to PCRs 8 - 9
Date:   Wed, 24 Jun 2020 17:33:37 -0400
Message-Id: <20200624213337.4214-1-maurizio.drocco@ibm.com>
In-Reply-To: <92a0d170-8157-476b-8083-ae567b11f364@linux.ibm.com>
References: <92a0d170-8157-476b-8083-ae567b11f364@linux.ibm.com>
Sender: linux-kernel-owner@vger.kernel.org
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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