linux-kernel - [PATCH] ima_evm_utils: extended calc_bootaggr to PCRs 8

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Message-Id: <20200618201126.2081-2-maurizio.drocco@ibm.com>
Date:   Thu, 18 Jun 2020 16:11:26 -0400
From:   Maurizio Drocco <maurizio.drocco@....com>
To:     roberto.sassu@...wei.com
Cc:     Silviu.Vlasceanu@...wei.com, dmitry.kasatkin@...il.com,
        jejb@...ux.ibm.com, jmorris@...ei.org,
        linux-integrity@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-security-module@...r.kernel.org, maurizio.drocco@....com,
        serge@...lyn.com, zohar@...ux.ibm.com, mdrocco@...ux.vnet.ibm.com
Subject: [PATCH] ima_evm_utils: extended calc_bootaggr to PCRs 8 - 9

From: Maurizio <maurizio.drocco@....com>

If PCRs 8 - 9 are set (i.e. not all-zeros), cal_bootaggr should include
them into the digest.

Signed-off-by: Maurizio Drocco <maurizio.drocco@....com>
---
 src/evmctl.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/src/evmctl.c b/src/evmctl.c
index 1d065ce..554571e 100644
--- a/src/evmctl.c
+++ b/src/evmctl.c
@@ -1930,6 +1930,18 @@ static void calc_bootaggr(struct tpm_bank_info *bank)
 		}
 	}
 
+	if (strcmp(bank->algo_name, "sha1") != 0) {
+		for (i = 8; i < 10; i++) {
+			if (memcmp(bank->pcr[i], zero, bank->digest_size) != 0) {
+				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");
@@ -1973,7 +1985,9 @@ 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.
+ * PCRs 0 - 9 to validate against the IMA boot_aggregate record. If PCRs
+ * 8 - 9 are not set (i.e. all-zeros) or the digest algorithm is SHA1, only
+ * PCRs 0 - 7 are considered.
  */
 static int cmd_ima_bootaggr(struct command *cmd)
 {
-- 
2.17.1