Re: [v2] [PATCH 2/3] tpm: use more algorithms than sha256 on pcr_read

On Tue, Nov 23, 2021 at 05:23:34PM +0530, Ruchika Gupta wrote:

The current tpm2_pcr_read is hardcoded using SHA256. Make the actual command to TPM configurable to use wider range of algorithms. The current command line is kept as is i.e limited to SHA-256 only.

Signed-off-by: Ruchika Gupta ruchika.gupta@linaro.org

v2: Change algorithm from u32 to u16 Add parameter description in function declaration

cmd/tpm-v2.c | 3 ++- include/tpm-v2.h | 5 ++++- lib/tpm-v2.c | 12 ++++++++---- 3 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/cmd/tpm-v2.c b/cmd/tpm-v2.c index daae91100a..4ea5f9f094 100644 --- a/cmd/tpm-v2.c +++ b/cmd/tpm-v2.c @@ -151,7 +151,8 @@ static int do_tpm_pcr_read(struct cmd_tbl *cmdtp, int flag, int argc,

data = map_sysmem(simple_strtoul(argv[2], NULL, 0), 0);

• rc = tpm2_pcr_read(dev, index, priv->pcr_select_min, data, &updates);

• rc = tpm2_pcr_read(dev, index, priv->pcr_select_min, TPM2_ALG_SHA256,

• 	   data, TPM2_DIGEST_LEN, &updates);
  

  if (!rc) { printf("PCR #%u content (%u known updates):\n", index, updates); print_byte_string(data, TPM2_DIGEST_LEN);

diff --git a/include/tpm-v2.h b/include/tpm-v2.h index ceff7d245e..4e9dd52cb6 100644 --- a/include/tpm-v2.h +++ b/include/tpm-v2.h @@ -512,13 +512,16 @@ u32 tpm2_nv_write_value(struct udevice *dev, u32 index, const void *data,

• @dev TPM device
• @idx Index of the PCR
• @idx_min_sz Minimum size in bytes of the pcrSelect array

• • @algorithm Algorithm used, defined in 'enum tpm2_algorithms'
  • @data Output buffer for contents of the named PCR
• • @digest_len len of the data
  • @updates Optional out parameter: number of updates for this PCR
  • @return code of the operation
  */

u32 tpm2_pcr_read(struct udevice *dev, u32 idx, unsigned int idx_min_sz,

•   void *data, unsigned int *updates);
  

•   u16 algorithm, void *data, u32 digest_len,
  

•   unsigned int *updates);
  
  

/**

• Issue a TPM2_GetCapability command. This implementation is limited

diff --git a/lib/tpm-v2.c b/lib/tpm-v2.c index 2e7b27bd6b..1bf627853a 100644 --- a/lib/tpm-v2.c +++ b/lib/tpm-v2.c @@ -254,7 +254,8 @@ u32 tpm2_nv_write_value(struct udevice *dev, u32 index, const void *data, }

u32 tpm2_pcr_read(struct udevice *dev, u32 idx, unsigned int idx_min_sz,

•   void *data, unsigned int *updates)
  

•   u16 algorithm, void *data, u32 digest_len,
  

•   unsigned int *updates)
  

{ u8 idx_array_sz = max(idx_min_sz, DIV_ROUND_UP(idx, 8)); u8 command_v2[COMMAND_BUFFER_SIZE] = { @@ -264,7 +265,7 @@ u32 tpm2_pcr_read(struct udevice *dev, u32 idx, unsigned int idx_min_sz,

/* TPML_PCR_SELECTION */
tpm_u32(1),			/* Number of selections */

• tpm_u16(TPM2_ALG_SHA256),	/* Algorithm of the hash */
  

• tpm_u16(algorithm),		/* Algorithm of the hash */
  

  idx_array_sz, /* Array size for selection */ /* bitmap(idx) Selected PCR bitmap */ };

@@ -283,10 +284,13 @@ u32 tpm2_pcr_read(struct udevice *dev, u32 idx, unsigned int idx_min_sz, if (ret) return ret;

• if (digest_len > response_len)

• return TPM_LIB_ERROR;
  

• if (unpack_byte_string(response, response_len, "ds", 10, &counter,

• 	       response_len - TPM2_DIGEST_LEN, data,
  

• 	       TPM2_DIGEST_LEN))
  

• 	       response_len - digest_len, data,
  

• 	       digest_len))
  

  return TPM_LIB_ERROR;

  if (updates)

-- 2.25.1

Reviewed-by: Ilias Apalodimas ilias.apalodimas@linaro.org