diff options
Diffstat (limited to 'lib/tpm.c')
| -rw-r--r-- | lib/tpm.c | 351 |
1 files changed, 350 insertions, 1 deletions
@@ -1,5 +1,6 @@ /* * Copyright (c) 2013 The Chromium OS Authors. + * Coypright (c) 2013 Guntermann & Drunck GmbH * * See file CREDITS for list of people who contributed to this * project. @@ -22,6 +23,7 @@ #include <common.h> #include <stdarg.h> +#include <sha1.h> #include <tpm.h> #include <asm/unaligned.h> @@ -35,8 +37,31 @@ enum { TPM_REQUEST_HEADER_LENGTH = 10, TPM_RESPONSE_HEADER_LENGTH = 10, PCR_DIGEST_LENGTH = 20, + DIGEST_LENGTH = 20, + TPM_REQUEST_AUTH_LENGTH = 45, + TPM_RESPONSE_AUTH_LENGTH = 41, + /* some max lengths, valid for RSA keys <= 2048 bits */ + TPM_KEY12_MAX_LENGTH = 618, + TPM_PUBKEY_MAX_LENGTH = 288, }; +#ifdef CONFIG_TPM_AUTH_SESSIONS + +#ifndef CONFIG_SHA1 +#error "TPM_AUTH_SESSIONS require SHA1 to be configured, too" +#endif /* !CONFIG_SHA1 */ + +struct session_data { + int valid; + uint32_t handle; + uint8_t nonce_even[DIGEST_LENGTH]; + uint8_t nonce_odd[DIGEST_LENGTH]; +}; + +static struct session_data oiap_session = {0, }; + +#endif /* CONFIG_TPM_AUTH_SESSIONS */ + /** * Pack data into a byte string. The data types are specified in * the format string: 'b' means unsigned byte, 'w' unsigned word, @@ -235,7 +260,7 @@ static uint32_t tpm_sendrecv_command(const void *command, response, &response_length); if (err) return TPM_LIB_ERROR; - if (response) + if (size_ptr) *size_ptr = response_length; return tpm_return_code(response); @@ -579,3 +604,327 @@ uint32_t tpm_get_capability(uint32_t cap_area, uint32_t sub_cap, return 0; } + +#ifdef CONFIG_TPM_AUTH_SESSIONS + +/** + * Fill an authentication block in a request. + * This func can create the first as well as the second auth block (for + * double authorized commands). + * + * @param request pointer to the request (w/ uninitialised auth data) + * @param request_len0 length of the request without auth data + * @param handles_len length of the handles area in request + * @param auth_session pointer to the (valid) auth session to be used + * @param request_auth pointer to the auth block of the request to be filled + * @param auth authentication data (HMAC key) + */ +static uint32_t create_request_auth(const void *request, size_t request_len0, + size_t handles_len, + struct session_data *auth_session, + void *request_auth, const void *auth) +{ + uint8_t hmac_data[DIGEST_LENGTH * 3 + 1]; + sha1_context hash_ctx; + const size_t command_code_offset = 6; + const size_t auth_nonce_odd_offset = 4; + const size_t auth_continue_offset = 24; + const size_t auth_auth_offset = 25; + + if (!auth_session || !auth_session->valid) + return TPM_LIB_ERROR; + + sha1_starts(&hash_ctx); + sha1_update(&hash_ctx, request + command_code_offset, 4); + if (request_len0 > TPM_REQUEST_HEADER_LENGTH + handles_len) + sha1_update(&hash_ctx, + request + TPM_REQUEST_HEADER_LENGTH + handles_len, + request_len0 - TPM_REQUEST_HEADER_LENGTH + - handles_len); + sha1_finish(&hash_ctx, hmac_data); + + sha1_starts(&hash_ctx); + sha1_update(&hash_ctx, auth_session->nonce_odd, DIGEST_LENGTH); + sha1_update(&hash_ctx, hmac_data, sizeof(hmac_data)); + sha1_finish(&hash_ctx, auth_session->nonce_odd); + + if (pack_byte_string(request_auth, TPM_REQUEST_AUTH_LENGTH, "dsb", + 0, auth_session->handle, + auth_nonce_odd_offset, auth_session->nonce_odd, + DIGEST_LENGTH, + auth_continue_offset, 1)) + return TPM_LIB_ERROR; + if (pack_byte_string(hmac_data, sizeof(hmac_data), "ss", + DIGEST_LENGTH, + auth_session->nonce_even, + DIGEST_LENGTH, + 2 * DIGEST_LENGTH, + request_auth + auth_nonce_odd_offset, + DIGEST_LENGTH + 1)) + return TPM_LIB_ERROR; + sha1_hmac(auth, DIGEST_LENGTH, hmac_data, sizeof(hmac_data), + request_auth + auth_auth_offset); + + return TPM_SUCCESS; +} + +/** + * Verify an authentication block in a response. + * Since this func updates the nonce_even in the session data it has to be + * called when receiving a succesfull AUTH response. + * This func can verify the first as well as the second auth block (for + * double authorized commands). + * + * @param command_code command code of the request + * @param response pointer to the request (w/ uninitialised auth data) + * @param handles_len length of the handles area in response + * @param auth_session pointer to the (valid) auth session to be used + * @param response_auth pointer to the auth block of the response to be verified + * @param auth authentication data (HMAC key) + */ +static uint32_t verify_response_auth(uint32_t command_code, + const void *response, size_t response_len0, + size_t handles_len, + struct session_data *auth_session, + const void *response_auth, const void *auth) +{ + uint8_t hmac_data[DIGEST_LENGTH * 3 + 1]; + uint8_t computed_auth[DIGEST_LENGTH]; + sha1_context hash_ctx; + const size_t return_code_offset = 6; + const size_t auth_continue_offset = 20; + const size_t auth_auth_offset = 21; + uint8_t auth_continue; + + if (!auth_session || !auth_session->valid) + return TPM_AUTHFAIL; + if (pack_byte_string(hmac_data, sizeof(hmac_data), "d", + 0, command_code)) + return TPM_LIB_ERROR; + if (response_len0 < TPM_RESPONSE_HEADER_LENGTH) + return TPM_LIB_ERROR; + + sha1_starts(&hash_ctx); + sha1_update(&hash_ctx, response + return_code_offset, 4); + sha1_update(&hash_ctx, hmac_data, 4); + if (response_len0 > TPM_RESPONSE_HEADER_LENGTH + handles_len) + sha1_update(&hash_ctx, + response + TPM_RESPONSE_HEADER_LENGTH + handles_len, + response_len0 - TPM_RESPONSE_HEADER_LENGTH + - handles_len); + sha1_finish(&hash_ctx, hmac_data); + + memcpy(auth_session->nonce_even, response_auth, DIGEST_LENGTH); + auth_continue = ((uint8_t *)response_auth)[auth_continue_offset]; + if (pack_byte_string(hmac_data, sizeof(hmac_data), "ssb", + DIGEST_LENGTH, + response_auth, + DIGEST_LENGTH, + 2 * DIGEST_LENGTH, + auth_session->nonce_odd, + DIGEST_LENGTH, + 3 * DIGEST_LENGTH, + auth_continue)) + return TPM_LIB_ERROR; + + sha1_hmac(auth, DIGEST_LENGTH, hmac_data, sizeof(hmac_data), + computed_auth); + + if (memcmp(computed_auth, response_auth + auth_auth_offset, + DIGEST_LENGTH)) + return TPM_AUTHFAIL; + + return TPM_SUCCESS; +} + + +uint32_t tpm_terminate_auth_session(uint32_t auth_handle) +{ + const uint8_t command[18] = { + 0x00, 0xc1, /* TPM_TAG */ + 0x00, 0x00, 0x00, 0x00, /* parameter size */ + 0x00, 0x00, 0x00, 0xba, /* TPM_COMMAND_CODE */ + 0x00, 0x00, 0x00, 0x00, /* TPM_HANDLE */ + 0x00, 0x00, 0x00, 0x02, /* TPM_RESSOURCE_TYPE */ + }; + const size_t req_handle_offset = TPM_REQUEST_HEADER_LENGTH; + uint8_t request[COMMAND_BUFFER_SIZE]; + + if (pack_byte_string(request, sizeof(request), "sd", + 0, command, sizeof(command), + req_handle_offset, auth_handle)) + return TPM_LIB_ERROR; + if (oiap_session.valid && oiap_session.handle == auth_handle) + oiap_session.valid = 0; + + return tpm_sendrecv_command(request, NULL, NULL); +} + +uint32_t tpm_end_oiap(void) +{ + uint32_t err = TPM_SUCCESS; + if (oiap_session.valid) + err = tpm_terminate_auth_session(oiap_session.handle); + return err; +} + +uint32_t tpm_oiap(uint32_t *auth_handle) +{ + const uint8_t command[10] = { + 0x00, 0xc1, /* TPM_TAG */ + 0x00, 0x00, 0x00, 0x0a, /* parameter size */ + 0x00, 0x00, 0x00, 0x0a, /* TPM_COMMAND_CODE */ + }; + const size_t res_auth_handle_offset = TPM_RESPONSE_HEADER_LENGTH; + const size_t res_nonce_even_offset = TPM_RESPONSE_HEADER_LENGTH + 4; + uint8_t response[COMMAND_BUFFER_SIZE]; + size_t response_length = sizeof(response); + uint32_t err; + + if (oiap_session.valid) + tpm_terminate_auth_session(oiap_session.handle); + + err = tpm_sendrecv_command(command, response, &response_length); + if (err) + return err; + if (unpack_byte_string(response, response_length, "ds", + res_auth_handle_offset, &oiap_session.handle, + res_nonce_even_offset, &oiap_session.nonce_even, + (uint32_t)DIGEST_LENGTH)) + return TPM_LIB_ERROR; + oiap_session.valid = 1; + if (auth_handle) + *auth_handle = oiap_session.handle; + return 0; +} + +uint32_t tpm_load_key2_oiap(uint32_t parent_handle, + const void *key, size_t key_length, + const void *parent_key_usage_auth, + uint32_t *key_handle) +{ + const uint8_t command[14] = { + 0x00, 0xc2, /* TPM_TAG */ + 0x00, 0x00, 0x00, 0x00, /* parameter size */ + 0x00, 0x00, 0x00, 0x41, /* TPM_COMMAND_CODE */ + 0x00, 0x00, 0x00, 0x00, /* parent handle */ + }; + const size_t req_size_offset = 2; + const size_t req_parent_handle_offset = TPM_REQUEST_HEADER_LENGTH; + const size_t req_key_offset = TPM_REQUEST_HEADER_LENGTH + 4; + const size_t res_handle_offset = TPM_RESPONSE_HEADER_LENGTH; + uint8_t request[sizeof(command) + TPM_KEY12_MAX_LENGTH + + TPM_REQUEST_AUTH_LENGTH]; + uint8_t response[COMMAND_BUFFER_SIZE]; + size_t response_length = sizeof(response); + uint32_t err; + + if (!oiap_session.valid) { + err = tpm_oiap(NULL); + if (err) + return err; + } + if (pack_byte_string(request, sizeof(request), "sdds", + 0, command, sizeof(command), + req_size_offset, + sizeof(command) + key_length + + TPM_REQUEST_AUTH_LENGTH, + req_parent_handle_offset, parent_handle, + req_key_offset, key, key_length + )) + return TPM_LIB_ERROR; + + err = create_request_auth(request, sizeof(command) + key_length, 4, + &oiap_session, + request + sizeof(command) + key_length, + parent_key_usage_auth); + if (err) + return err; + err = tpm_sendrecv_command(request, response, &response_length); + if (err) { + if (err == TPM_AUTHFAIL) + oiap_session.valid = 0; + return err; + } + + err = verify_response_auth(0x00000041, response, + response_length - TPM_RESPONSE_AUTH_LENGTH, + 4, &oiap_session, + response + response_length - TPM_RESPONSE_AUTH_LENGTH, + parent_key_usage_auth); + if (err) + return err; + + if (key_handle) { + if (unpack_byte_string(response, response_length, "d", + res_handle_offset, key_handle)) + return TPM_LIB_ERROR; + } + + return 0; +} + +uint32_t tpm_get_pub_key_oiap(uint32_t key_handle, const void *usage_auth, + void *pubkey, size_t *pubkey_len) +{ + const uint8_t command[14] = { + 0x00, 0xc2, /* TPM_TAG */ + 0x00, 0x00, 0x00, 0x00, /* parameter size */ + 0x00, 0x00, 0x00, 0x21, /* TPM_COMMAND_CODE */ + 0x00, 0x00, 0x00, 0x00, /* key handle */ + }; + const size_t req_size_offset = 2; + const size_t req_key_handle_offset = TPM_REQUEST_HEADER_LENGTH; + const size_t res_pubkey_offset = TPM_RESPONSE_HEADER_LENGTH; + uint8_t request[sizeof(command) + TPM_REQUEST_AUTH_LENGTH]; + uint8_t response[TPM_RESPONSE_HEADER_LENGTH + TPM_PUBKEY_MAX_LENGTH + + TPM_RESPONSE_AUTH_LENGTH]; + size_t response_length = sizeof(response); + uint32_t err; + + if (!oiap_session.valid) { + err = tpm_oiap(NULL); + if (err) + return err; + } + if (pack_byte_string(request, sizeof(request), "sdd", + 0, command, sizeof(command), + req_size_offset, + (uint32_t)(sizeof(command) + + TPM_REQUEST_AUTH_LENGTH), + req_key_handle_offset, key_handle + )) + return TPM_LIB_ERROR; + err = create_request_auth(request, sizeof(command), 4, &oiap_session, + request + sizeof(command), usage_auth); + if (err) + return err; + err = tpm_sendrecv_command(request, response, &response_length); + if (err) { + if (err == TPM_AUTHFAIL) + oiap_session.valid = 0; + return err; + } + err = verify_response_auth(0x00000021, response, + response_length - TPM_RESPONSE_AUTH_LENGTH, + 0, &oiap_session, + response + response_length - TPM_RESPONSE_AUTH_LENGTH, + usage_auth); + if (err) + return err; + + if (pubkey) { + if ((response_length - TPM_RESPONSE_HEADER_LENGTH + - TPM_RESPONSE_AUTH_LENGTH) > *pubkey_len) + return TPM_LIB_ERROR; + *pubkey_len = response_length - TPM_RESPONSE_HEADER_LENGTH + - TPM_RESPONSE_AUTH_LENGTH; + memcpy(pubkey, response + res_pubkey_offset, + response_length - TPM_RESPONSE_HEADER_LENGTH + - TPM_RESPONSE_AUTH_LENGTH); + } + + return 0; +} + +#endif /* CONFIG_TPM_AUTH_SESSIONS */ |