On Mon, Jul 05, 2021 at 09:48:49AM -0600, Simon Glass wrote:
> It is fairly easy to handle this case and it makes the emulator more
> useful, since PCRs are commonly extended several times.
>
> Add support for this, using U-Boot's sha256 support.
>
> Signed-off-by: Simon Glass <s...@chromium.org>
> ---
>
> drivers/tpm/tpm2_tis_sandbox.c | 19 ++++++++++++-------
> 1 file changed, 12 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/tpm/tpm2_tis_sandbox.c b/drivers/tpm/tpm2_tis_sandbox.c
> index ed9c9a0bc9f..e84bcc7c4c8 100644
> --- a/drivers/tpm/tpm2_tis_sandbox.c
> +++ b/drivers/tpm/tpm2_tis_sandbox.c
> @@ -11,6 +11,7 @@
> #include <asm/unaligned.h>
> #include <linux/bitops.h>
> #include <u-boot/crc.h>
> +#include <u-boot/sha256.h>
> #include "sandbox_common.h"
>
> /* Hierarchies */
> @@ -407,15 +408,19 @@ static int sandbox_tpm2_extend(struct udevice *dev, int
> pcr_index,
> const u8 *extension)
> {
> struct sandbox_tpm2 *tpm = dev_get_priv(dev);
> - int i;
>
> - /* Only simulate the first extensions from all '0' with only '0' */
> - for (i = 0; i < TPM2_DIGEST_LEN; i++)
> - if (tpm->pcr[pcr_index][i] || extension[i])
> - return TPM2_RC_FAILURE;
> + if (!pcr_index) {
> + memcpy(tpm->pcr[pcr_index], sandbox_extended_once_pcr,
> + TPM2_DIGEST_LEN);
Why do we have to treat pcr 0 specially?
Can't we just get rid of sandbox_extended_once_pcr and just extend all the
PCRs with the value wee get?
> + } else {
> + sha256_context ctx;
> +
> + sha256_starts(&ctx);
> + sha256_update(&ctx, tpm->pcr[pcr_index], TPM2_DIGEST_LEN);
> + sha256_update(&ctx, extension, TPM2_DIGEST_LEN);
> + sha256_finish(&ctx, tpm->pcr[pcr_index]);
> + }
>
> - memcpy(tpm->pcr[pcr_index], sandbox_extended_once_pcr,
> - TPM2_DIGEST_LEN);
> tpm->pcr_extensions[pcr_index]++;
>
> return 0;
> --
> 2.32.0.93.g670b81a890-goog
>
