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tpm: use more than sha256 on pcr_extend

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The current tpm2_pcr_extend is hardcoded using SHA256.
Let's make the actual command to the TPM2 configurable so we can support
a wider range of algorithms and keep the current command line as-is i.e
limited to SHA256 only

Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
This commit is contained in:
Ilias Apalodimas 2020-11-26 23:07:22 +02:00 • committed by Heinrich Schuchardt
parent fc364424ac
commit e926136bb2
3 changed files with 12 additions and 7 deletions
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3
cmd/tpm-v2.c
View file

@ -116,7 +116,8 @@ static int do_tpm2_pcr_extend(struct cmd_tbl *cmdtp, int flag, int argc,
if (index >= priv->pcr_count)
return -EINVAL;
rc = tpm2_pcr_extend(dev, index, digest);
rc = tpm2_pcr_extend(dev, index, TPM2_ALG_SHA256, digest,
TPM2_DIGEST_LEN);
unmap_sysmem(digest);

5
include/tpm-v2.h
View file

@ -309,11 +309,14 @@ u32 tpm2_clear(struct udevice *dev, u32 handle, const char *pw,
*
* @dev TPM device
* @index Index of the PCR
* @algorithm Algorithm used, defined in 'enum tpm2_algorithms'
* @digest Value representing the event to be recorded
* @digest_len len of the hash
*
* @return code of the operation
*/
u32 tpm2_pcr_extend(struct udevice *dev, u32 index, const uint8_t *digest);
u32 tpm2_pcr_extend(struct udevice *dev, u32 index, u32 algorithm,
const u8 *digest, u32 digest_len);
/**
* Issue a TPM2_PCR_Read command.

11
lib/tpm-v2.c
View file

@ -80,11 +80,12 @@ u32 tpm2_clear(struct udevice *dev, u32 handle, const char *pw,
return tpm_sendrecv_command(dev, command_v2, NULL, NULL);
}
u32 tpm2_pcr_extend(struct udevice *dev, u32 index, const uint8_t *digest)
u32 tpm2_pcr_extend(struct udevice *dev, u32 index, u32 algorithm,
const u8 *digest, u32 digest_len)
{
u8 command_v2[COMMAND_BUFFER_SIZE] = {
tpm_u16(TPM2_ST_SESSIONS), /* TAG */
tpm_u32(33 + TPM2_DIGEST_LEN), /* Length */
tpm_u32(33 + digest_len), /* Length */
tpm_u32(TPM2_CC_PCR_EXTEND), /* Command code */
/* HANDLE */
@ -99,7 +100,7 @@ u32 tpm2_pcr_extend(struct udevice *dev, u32 index, const uint8_t *digest)
tpm_u16(0), /* Size of <hmac/password> */
/* <hmac/password> (if any) */
tpm_u32(1), /* Count (number of hashes) */
tpm_u16(TPM2_ALG_SHA256), /* Algorithm of the hash */
tpm_u16(algorithm), /* Algorithm of the hash */
/* STRING(digest) Digest */
};
unsigned int offset = 33;
@ -110,8 +111,8 @@ u32 tpm2_pcr_extend(struct udevice *dev, u32 index, const uint8_t *digest)
* - the digest
*/
ret = pack_byte_string(command_v2, sizeof(command_v2), "s",
offset, digest, TPM2_DIGEST_LEN);
offset += TPM2_DIGEST_LEN;
offset, digest, digest_len);
offset += digest_len;
if (ret)
return TPM_LIB_ERROR;