diff options
Diffstat (limited to 'common/fpsensor.c')
| -rw-r--r-- | common/fpsensor.c | 49 |
1 files changed, 43 insertions, 6 deletions
diff --git a/common/fpsensor.c b/common/fpsensor.c index dec669ec9a..d2f4a6297f 100644 --- a/common/fpsensor.c +++ b/common/fpsensor.c @@ -42,7 +42,7 @@ #define FP_MAX_FINGER_COUNT 0 #endif #define SBP_ENC_KEY_LEN 16 -#define FP_TEMPLATE_FORMAT_VERSION 2 +#define FP_TEMPLATE_FORMAT_VERSION 3 #define FP_ALGORITHM_ENCRYPTED_TEMPLATE_SIZE \ (FP_ALGORITHM_TEMPLATE_SIZE + \ sizeof(struct ec_fp_template_encryption_metadata)) @@ -76,6 +76,10 @@ static uint32_t templ_dirty; static uint32_t user_id[FP_CONTEXT_USERID_WORDS]; /* Ready to encrypt a template. */ static timestamp_t encryption_deadline; +/* Part of the IKM used to derive encryption keys received from the TPM. */ +static uint8_t tpm_seed[FP_CONTEXT_TPM_BYTES]; +/* Flag indicating whether the seed has been initialised or not. */ +static int fp_tpm_seed_is_set; #define CPRINTF(format, args...) cprintf(CC_FP, format, ## args) #define CPRINTS(format, args...) cprints(CC_FP, format, ## args) @@ -348,26 +352,39 @@ static int derive_encryption_key(uint8_t *out_key, uint8_t *salt) int ret; uint8_t key_buf[SHA256_DIGEST_SIZE]; uint8_t prk[SHA256_DIGEST_SIZE]; - uint8_t rb_secret[CONFIG_ROLLBACK_SECRET_SIZE]; uint8_t message[sizeof(user_id) + 1]; + uint8_t ikm[CONFIG_ROLLBACK_SECRET_SIZE + sizeof(tpm_seed)]; BUILD_ASSERT(SBP_ENC_KEY_LEN <= SHA256_DIGEST_SIZE); BUILD_ASSERT(SBP_ENC_KEY_LEN <= CONFIG_ROLLBACK_SECRET_SIZE); BUILD_ASSERT(sizeof(user_id) == SHA256_DIGEST_SIZE); - ret = rollback_get_secret(rb_secret); + if (!fp_tpm_seed_is_set) { + CPRINTS("Seed hasn't been set."); + return EC_RES_ERROR; + } + + /* + * The first CONFIG_ROLLBACK_SECRET_SIZE bytes of IKM are read from the + * anti-rollback blocks. + */ + ret = rollback_get_secret(ikm); if (ret != EC_SUCCESS) { CPRINTS("Failed to read rollback secret: %d", ret); return EC_RES_ERROR; } + /* + * IKM is the concatenation of the rollback secret and the seed from + * the TPM. + */ + memcpy(ikm + CONFIG_ROLLBACK_SECRET_SIZE, tpm_seed, sizeof(tpm_seed)); /* * Derive a key with the "extract" step of HKDF * https://tools.ietf.org/html/rfc5869#section-2.2 */ - hmac_SHA256(prk, salt, FP_CONTEXT_SALT_BYTES, rb_secret, - sizeof(rb_secret)); - memset(rb_secret, 0, sizeof(rb_secret)); + hmac_SHA256(prk, salt, FP_CONTEXT_SALT_BYTES, ikm, sizeof(ikm)); + memset(ikm, 0, sizeof(ikm)); /* * Only 1 "expand" step of HKDF since the size of the "info" context @@ -782,6 +799,26 @@ static int fp_command_context(struct host_cmd_handler_args *args) } DECLARE_HOST_COMMAND(EC_CMD_FP_CONTEXT, fp_command_context, EC_VER_MASK(0)); +static int fp_command_tpm_seed(struct host_cmd_handler_args *args) +{ + const struct ec_params_fp_seed *params = args->params; + + if (params->struct_version != FP_TEMPLATE_FORMAT_VERSION) { + CPRINTS("Invalid seed format %d", params->struct_version); + return EC_RES_INVALID_PARAM; + } + + if (fp_tpm_seed_is_set) { + CPRINTS("Seed has already been set."); + return EC_RES_ACCESS_DENIED; + } + memcpy(tpm_seed, params->seed, sizeof(tpm_seed)); + fp_tpm_seed_is_set = 1; + + return EC_RES_SUCCESS; +} +DECLARE_HOST_COMMAND(EC_CMD_FP_SEED, fp_command_tpm_seed, EC_VER_MASK(0)); + #ifdef CONFIG_CMD_FPSENSOR_DEBUG /* --- Debug console commands --- */ |