Hi Maurizio,
When re-posting patches, please include the version number (e.g.
[PATCH v4] ima: ... ).
On Mon, 2020-06-22 at 00:50 -0400, Maurizio Drocco wrote:
> IMA is not considering TPM registers 8-9 when calculating the boot
> aggregate.
This line is unnecessary with the following change.
> When registers 8-9 are used to store measurements of the
> kernel and its command line (e.g., grub2 bootloader with tpm module
> enabled), IMA should include them in the boot aggregate.
The "When" clause makes this sound like PCRs 8 & 9 are not always
included. I would split this into two sentences.
> Registers
> 8-9 are only included in non-SHA1 boot_aggregate digests to avoid
> ambiguity.
>
> Signed-off-by: Maurizio Drocco <maurizio.dro...@ibm.com>
> ---
Missing "Changelog:".
Changelog:
v2:
- Limit including PCRs 8 & 9 to non-sha1 hashes
v1:
- Include non zero PCRs 8 & 9 in the boot_aggregate
> security/integrity/ima/ima.h | 2 +-
> security/integrity/ima/ima_crypto.c | 15 ++++++++++++++-
> 2 files changed, 15 insertions(+), 2 deletions(-)
>
> diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
> index df93ac258e01..9d94080bdad8 100644
> --- a/security/integrity/ima/ima.h
> +++ b/security/integrity/ima/ima.h
> @@ -30,7 +30,7 @@
>
> enum ima_show_type { IMA_SHOW_BINARY, IMA_SHOW_BINARY_NO_FIELD_LEN,
> IMA_SHOW_BINARY_OLD_STRING_FMT, IMA_SHOW_ASCII };
> -enum tpm_pcrs { TPM_PCR0 = 0, TPM_PCR8 = 8 };
> +enum tpm_pcrs { TPM_PCR0 = 0, TPM_PCR8 = 8, TPM_PCR10 = 10 };
>
> /* digest size for IMA, fits SHA1 or MD5 */
> #define IMA_DIGEST_SIZE SHA1_DIGEST_SIZE
> diff --git a/security/integrity/ima/ima_crypto.c
> b/security/integrity/ima/ima_crypto.c
> index 220b14920c37..d02917d85033 100644
> --- a/security/integrity/ima/ima_crypto.c
> +++ b/security/integrity/ima/ima_crypto.c
> @@ -823,13 +823,26 @@ static int ima_calc_boot_aggregate_tfm(char *digest,
> u16 alg_id,
> if (rc != 0)
> return rc;
>
> - /* cumulative sha1 over tpm registers 0-7 */
> + /* cumulative digest over tpm registers 0-7 */
Please uppercase "tpm" here and below.
> for (i = TPM_PCR0; i < TPM_PCR8; i++) {
> ima_pcrread(i, &d);
> /* now accumulate with current aggregate */
> rc = crypto_shash_update(shash, d.digest,
> crypto_shash_digestsize(tfm));
> }
> + /*
> + * extend cumulative digest over tpm registers 8-9, which contain
> + * measurement for the kernel command line (reg. 8) and image (reg. 9)
> + * in a typical PCR allocation. Registers 8-9 are only included in
> + * non-SHA1 boot_aggregate digests to avoid ambiguity.
> + */
Comments that are full sentences should start with an uppercase letter
and end with a period (e.g. Extend).
thanks,
Mimi
> + if (alg_id != TPM_ALG_SHA1) {
> + for (i = TPM_PCR8; i < TPM_PCR10; i++) {
> + ima_pcrread(i, &d);
> + rc = crypto_shash_update(shash, d.digest,
> + crypto_shash_digestsize(tfm));
> + }
> + }
> if (!rc)
> crypto_shash_final(shash, digest);
> return rc;
