Add support for TPM2 GetRandom command
Signed-off-by: Dhananjay Phadke dphadke@linux.microsoft.com --- include/tpm-v2.h | 13 +++++++++++++ lib/tpm-v2.c | 44 ++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 57 insertions(+)
diff --git a/include/tpm-v2.h b/include/tpm-v2.h index ae00803f6d..513697e9a1 100644 --- a/include/tpm-v2.h +++ b/include/tpm-v2.h @@ -70,6 +70,7 @@ enum tpm2_handles { * @TPM2_CC_DAM_RESET: TPM2_DictionaryAttackLockReset(). * @TPM2_CC_DAM_PARAMETERS: TPM2_DictionaryAttackParameters(). * @TPM2_CC_GET_CAPABILITY: TPM2_GetCapibility(). + * @TPM2_CC_GET_RANDOM: TPM2_GetRandom(). * @TPM2_CC_PCR_READ: TPM2_PCR_Read(). * @TPM2_CC_PCR_EXTEND: TPM2_PCR_Extend(). * @TPM2_CC_PCR_SETAUTHVAL: TPM2_PCR_SetAuthValue(). @@ -85,6 +86,7 @@ enum tpm2_command_codes { TPM2_CC_DAM_PARAMETERS = 0x013A, TPM2_CC_NV_READ = 0x014E, TPM2_CC_GET_CAPABILITY = 0x017A, + TPM2_CC_GET_RANDOM = 0x017B, TPM2_CC_PCR_READ = 0x017E, TPM2_CC_PCR_EXTEND = 0x0182, TPM2_CC_PCR_SETAUTHVAL = 0x0183, @@ -308,4 +310,15 @@ u32 tpm2_pcr_setauthvalue(struct udevice *dev, const char *pw, const ssize_t pw_sz, u32 index, const char *key, const ssize_t key_sz);
+/** + * Issue a TPM2_GetRandom command. + * + * @dev TPM device + * @param data output buffer for the random bytes + * @param count size of output buffer + * + * @return return code of the operation + */ +u32 tpm2_get_random(struct udevice *dev, void *data, u32 count); + #endif /* __TPM_V2_H */ diff --git a/lib/tpm-v2.c b/lib/tpm-v2.c index f89592d6e2..9d078877bc 100644 --- a/lib/tpm-v2.c +++ b/lib/tpm-v2.c @@ -421,3 +421,47 @@ u32 tpm2_pcr_setauthvalue(struct udevice *dev, const char *pw,
return tpm_sendrecv_command(dev, command_v2, NULL, NULL); } + +u32 tpm2_get_random(struct udevice *dev, void *data, u32 count) +{ + const u8 command_v2[10] = { + tpm_u16(TPM2_ST_NO_SESSIONS), + tpm_u32(12), + tpm_u32(TPM2_CC_GET_RANDOM), + }; + u8 buf[COMMAND_BUFFER_SIZE], response[COMMAND_BUFFER_SIZE]; + + const size_t data_size_offset = 10; + const size_t data_offset = 12; + size_t response_length = sizeof(response); + u32 data_size; + u8 *out = data; + + while (count > 0) { + u32 this_bytes = min((size_t)count, + sizeof(response) - data_offset); + u32 err; + + if (pack_byte_string(buf, sizeof(buf), "sw", + 0, command_v2, sizeof(command_v2), + sizeof(command_v2), this_bytes)) + return TPM_LIB_ERROR; + err = tpm_sendrecv_command(dev, buf, response, + &response_length); + if (err) + return err; + if (unpack_byte_string(response, response_length, "w", + data_size_offset, &data_size)) + return TPM_LIB_ERROR; + if (data_size > this_bytes) + return TPM_LIB_ERROR; + if (unpack_byte_string(response, response_length, "s", + data_offset, out, data_size)) + return TPM_LIB_ERROR; + + count -= data_size; + out += data_size; + } + + return 0; +}