On 6/23/20 2:13 PM, Bruno Meneguele wrote:

On Tue, Jun 23, 2020 at 02:01:22PM -0400, Maurizio Drocco wrote:

quoted

From: Maurizio <redacted>

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

Wouldn't you have to check for not all-zeros in your code?


    Stefan

quoted

Signed-off-by: Maurizio Drocco <redacted>
---
Changelog:
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 <redacted>