Messages in this thread | | | Date | Mon, 27 Jan 2020 13:49:41 -0700 | From | Jerry Snitselaar <> | Subject | Re: [PATCH 1/2] ima: use the IMA configured hash algo to calculate the boot aggregate |
| |
On Mon Jan 27 20, Mimi Zohar wrote: >The boot aggregate is a cumulative SHA1 hash over TPM registers 0 - 7. >NIST has depreciated the usage of SHA1 in most instances. Instead of >continuing to use SHA1 to calculate the boot_aggregate, use the >configured IMA default hash algorithm. > >Although the IMA measurement list boot_aggregate template data contains >the hash algorithm followed by the digest, allowing verifiers (e.g. >attesttaion servers) to calculate and verify the boot_aggregate, the >verifiers might not have the knowledge of what constitutes a good value >based on a different hash algorithm. > >Signed-off-by: Mimi Zohar <zohar@linux.ibm.com> >--- > security/integrity/ima/ima_init.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > >diff --git a/security/integrity/ima/ima_init.c b/security/integrity/ima/ima_init.c >index 195cb4079b2b..b1b334fe0db5 100644 >--- a/security/integrity/ima/ima_init.c >+++ b/security/integrity/ima/ima_init.c >@@ -27,7 +27,7 @@ struct tpm_chip *ima_tpm_chip; > /* Add the boot aggregate to the IMA measurement list and extend > * the PCR register. > * >- * Calculate the boot aggregate, a SHA1 over tpm registers 0-7, >+ * Calculate the boot aggregate, a hash over tpm registers 0-7, > * assuming a TPM chip exists, and zeroes if the TPM chip does not > * exist. Add the boot aggregate measurement to the measurement > * list and extend the PCR register. >@@ -51,14 +51,14 @@ static int __init ima_add_boot_aggregate(void) > int violation = 0; > struct { > struct ima_digest_data hdr; >- char digest[TPM_DIGEST_SIZE]; >+ char digest[TPM_MAX_DIGEST_SIZE]; > } hash; > > memset(iint, 0, sizeof(*iint)); > memset(&hash, 0, sizeof(hash)); > iint->ima_hash = &hash.hdr; >- iint->ima_hash->algo = HASH_ALGO_SHA1; >- iint->ima_hash->length = SHA1_DIGEST_SIZE; >+ iint->ima_hash->algo = ima_hash_algo; >+ iint->ima_hash->length = hash_digest_size[ima_hash_algo]; > > if (ima_tpm_chip) { > result = ima_calc_boot_aggregate(&hash.hdr); >-- >2.7.5 >
Tested the patches on the Dell and no longer spits out the error messages on boot. /sys/kernel/security/ima/ascii_runtime_measurements shows the boot aggregate.
Is there something else I should look at to verify it is functioning properly?
Regards, Jerry
| |