On Wed, Mar 29, 2017 at 12:24:49PM +0200, Roberto Sassu wrote:
> TCG mandates that all PCR banks must be extended during the same operation.
> tpm2_pcr_extend() will check whether all digests have been provided.
>
> The check is necessary because tpm2_pcr_extend() will be called by a new
> function, allowing callers to provide a digest for each PCR bank.
>
> Signed-off-by: Roberto Sassu <[email protected]>
When can this happen?
/Jarkko
> ---
> drivers/char/tpm/tpm2-cmd.c | 23 +++++++++++++++++++++++
> 1 file changed, 23 insertions(+)
>
> diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
> index 881aea9..f4d534c 100644
> --- a/drivers/char/tpm/tpm2-cmd.c
> +++ b/drivers/char/tpm/tpm2-cmd.c
> @@ -284,6 +284,26 @@ struct tpm2_null_auth_area {
> __be16 auth_size;
> } __packed;
>
> +static bool tpm2_digests_all_banks(struct tpm_chip *chip, u32 count,
> + struct tpm2_digest *digests)
> +{
> + int i, j;
> +
> + for (i = 0; i < ARRAY_SIZE(chip->active_banks) &&
> + chip->active_banks[i] != TPM2_ALG_ERROR; i++) {
> + for (j = 0; j < count; j++)
> + if (digests[j].alg_id == chip->active_banks[i])
> + break;
> + if (j == count) {
> + pr_err("missing TPM algorithm 0x%x\n",
> + chip->active_banks[i]);
> + return false;
> + }
> + }
> +
> + return true;
> +}
> +
What if 'digests' contains the same 'alg_id' multiple times?
> /**
> * tpm2_pcr_extend() - extend a PCR value
> *
> @@ -306,6 +326,9 @@ int tpm2_pcr_extend(struct tpm_chip *chip, int pcr_idx,
> u32 count,
> if (count > ARRAY_SIZE(chip->active_banks))
> return -EINVAL;
>
> + if (!tpm2_digests_all_banks(chip, count, digests))
> + return -EINVAL;
> +
> rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_PCR_EXTEND);
> if (rc)
> return rc;
> --
> 2.9.3
>
>
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/Jarkko
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