[PATCH v6 2/3] tpm: use more algorithms than sha256 on pcr_read

[Ruchika Gupta]

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 at linaro.org>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas at linaro.org>
---
v6: No change

v5: No change

v4: No change

v3: No change

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