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SubjectRe: [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

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