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Diffstat (limited to 'lib/verify-tofu.c')
-rw-r--r-- | lib/verify-tofu.c | 767 |
1 files changed, 767 insertions, 0 deletions
diff --git a/lib/verify-tofu.c b/lib/verify-tofu.c new file mode 100644 index 0000000..97f4738 --- /dev/null +++ b/lib/verify-tofu.c @@ -0,0 +1,767 @@ +/* + * Copyright (C) 2012 Free Software Foundation, Inc. + * + * Author: Nikos Mavrogiannopoulos + * + * This file is part of GnuTLS. + * + * The GnuTLS is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public License + * as published by the Free Software Foundation; either version 2.1 of + * the License, or (at your option) any later version. + * + * This library is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public License + * along with this program. If not, see <https://www.gnu.org/licenses/> + * + */ + +#include "gnutls_int.h" +#include "errors.h" +#include <libtasn1.h> +#include <global.h> +#include <num.h> /* MAX */ +#include <tls-sig.h> +#include "str.h" +#include <datum.h> +#include "x509_int.h" +#include <nettle/base64.h> +#include <common.h> +#include <gnutls/abstract.h> +#include <system.h> +#include <locks.h> + +GNUTLS_STATIC_MUTEX(file_mutex); + +struct gnutls_tdb_int { + gnutls_tdb_store_func store; + gnutls_tdb_store_commitment_func cstore; + gnutls_tdb_verify_func verify; +}; + +static int raw_pubkey_to_base64(const gnutls_datum_t * raw, + gnutls_datum_t * b64); +static int verify_pubkey(const char *file, const char *host, + const char *service, const gnutls_datum_t * skey); + +static +int store_commitment(const char *db_name, const char *host, + const char *service, time_t expiration, + gnutls_digest_algorithm_t hash_algo, + const gnutls_datum_t * hash); +static +int store_pubkey(const char *db_name, const char *host, + const char *service, time_t expiration, + const gnutls_datum_t * pubkey); + +static int find_config_file(char *file, size_t max_size); + +struct gnutls_tdb_int default_tdb = { + store_pubkey, + store_commitment, + verify_pubkey +}; + + +/** + * gnutls_verify_stored_pubkey: + * @db_name: A file specifying the stored keys (use NULL for the default) + * @tdb: A storage structure or NULL to use the default + * @host: The peer's name + * @service: non-NULL if this key is specific to a service (e.g. http) + * @cert_type: The type of the certificate + * @cert: The raw (der) data of the certificate + * @flags: should be 0. + * + * This function will try to verify a raw public-key or a public-key provided via + * a raw (DER-encoded) certificate using a list of stored public keys. + * The @service field if non-NULL should be a port number. + * + * The @db_name variable if non-null specifies a custom backend for + * the retrieval of entries. If it is NULL then the + * default file backend will be used. In POSIX-like systems the + * file backend uses the $HOME/.gnutls/known_hosts file. + * + * Note that if the custom storage backend is provided the + * retrieval function should return %GNUTLS_E_CERTIFICATE_KEY_MISMATCH + * if the host/service pair is found but key doesn't match, + * %GNUTLS_E_NO_CERTIFICATE_FOUND if no such host/service with + * the given key is found, and 0 if it was found. The storage + * function should return 0 on success. + * + * As of GnuTLS 3.6.6 this function also verifies raw public keys. + * + * Returns: If no associated public key is found + * then %GNUTLS_E_NO_CERTIFICATE_FOUND will be returned. If a key + * is found but does not match %GNUTLS_E_CERTIFICATE_KEY_MISMATCH + * is returned. On success, %GNUTLS_E_SUCCESS (0) is returned, + * or a negative error value on other errors. + * + * Since: 3.0.13 + **/ +int +gnutls_verify_stored_pubkey(const char *db_name, + gnutls_tdb_t tdb, + const char *host, + const char *service, + gnutls_certificate_type_t cert_type, + const gnutls_datum_t * cert, + unsigned int flags) +{ + gnutls_datum_t pubkey = { NULL, 0 }; // Holds the pubkey in subjectPublicKeyInfo format (DER encoded) + int ret; + char local_file[MAX_FILENAME]; + bool need_free; + + + if (db_name == NULL && tdb == NULL) { + ret = find_config_file(local_file, sizeof(local_file)); + if (ret < 0) + return gnutls_assert_val(ret); + db_name = local_file; + } + + if (tdb == NULL) + tdb = &default_tdb; + + /* Import the public key depending on the provided certificate type */ + switch (cert_type) { + case GNUTLS_CRT_X509: + /* Extract the pubkey from the cert. This function does a malloc + * deep down the call chain. We are responsible for freeing. */ + ret = _gnutls_x509_raw_crt_to_raw_pubkey(cert, &pubkey); + + if (ret < 0) { + _gnutls_free_datum(&pubkey); + return gnutls_assert_val(ret); + } + + need_free = true; + break; + case GNUTLS_CRT_RAWPK: + pubkey.data = cert->data; + pubkey.size = cert->size; + need_free = false; + break; + default: + return gnutls_assert_val(GNUTLS_E_UNSUPPORTED_CERTIFICATE_TYPE); + } + + // Verify our pubkey against the database + ret = tdb->verify(db_name, host, service, &pubkey); + if (ret < 0 && ret != GNUTLS_E_CERTIFICATE_KEY_MISMATCH) + ret = gnutls_assert_val(GNUTLS_E_NO_CERTIFICATE_FOUND); + + if (need_free) { + _gnutls_free_datum(&pubkey); + } + + return ret; +} + +static int parse_commitment_line(char *line, + const char *host, size_t host_len, + const char *service, size_t service_len, + time_t now, const gnutls_datum_t * skey) +{ + char *p, *kp; + char *savep = NULL; + size_t kp_len, phash_size; + time_t expiration; + int ret; + const mac_entry_st *hash_algo; + uint8_t phash[MAX_HASH_SIZE]; + uint8_t hphash[MAX_HASH_SIZE * 2 + 1]; + + /* read host */ + p = strtok_r(line, "|", &savep); + if (p == NULL) + return gnutls_assert_val(GNUTLS_E_PARSING_ERROR); + + if (p[0] != '*' && host != NULL && strcmp(p, host) != 0) + return gnutls_assert_val(GNUTLS_E_PARSING_ERROR); + + /* read service */ + p = strtok_r(NULL, "|", &savep); + if (p == NULL) + return gnutls_assert_val(GNUTLS_E_PARSING_ERROR); + + if (p[0] != '*' && service != NULL && strcmp(p, service) != 0) + return gnutls_assert_val(GNUTLS_E_PARSING_ERROR); + + /* read expiration */ + p = strtok_r(NULL, "|", &savep); + if (p == NULL) + return gnutls_assert_val(GNUTLS_E_PARSING_ERROR); + + expiration = (time_t) atol(p); + if (expiration > 0 && now > expiration) + return gnutls_assert_val(GNUTLS_E_EXPIRED); + + /* read hash algorithm */ + p = strtok_r(NULL, "|", &savep); + if (p == NULL) + return gnutls_assert_val(GNUTLS_E_PARSING_ERROR); + + hash_algo = mac_to_entry(atol(p)); + if (_gnutls_digest_get_name(hash_algo) == NULL) + return gnutls_assert_val(GNUTLS_E_PARSING_ERROR); + + /* read hash */ + kp = strtok_r(NULL, "|", &savep); + if (kp == NULL) + return gnutls_assert_val(GNUTLS_E_PARSING_ERROR); + + p = strpbrk(kp, "\n \r\t|"); + if (p != NULL) + *p = 0; + + /* hash and hex encode */ + ret = + _gnutls_hash_fast((gnutls_digest_algorithm_t)hash_algo->id, + skey->data, skey->size, phash); + if (ret < 0) + return gnutls_assert_val(ret); + + phash_size = _gnutls_hash_get_algo_len(hash_algo); + + p = _gnutls_bin2hex(phash, phash_size, (void *) hphash, + sizeof(hphash), NULL); + if (p == NULL) + return gnutls_assert_val(GNUTLS_E_INTERNAL_ERROR); + + kp_len = strlen(kp); + if (kp_len != phash_size * 2) + return + gnutls_assert_val(GNUTLS_E_CERTIFICATE_KEY_MISMATCH); + + if (memcmp(kp, hphash, kp_len) != 0) + return + gnutls_assert_val(GNUTLS_E_CERTIFICATE_KEY_MISMATCH); + + /* key found and matches */ + return 0; +} + + +static int parse_line(char *line, + const char *host, size_t host_len, + const char *service, size_t service_len, + time_t now, + const gnutls_datum_t * rawkey, + const gnutls_datum_t * b64key) +{ + char *p, *kp; + char *savep = NULL; + size_t kp_len; + time_t expiration; + + /* read version */ + p = strtok_r(line, "|", &savep); + if (p == NULL) + return gnutls_assert_val(GNUTLS_E_PARSING_ERROR); + + if (strncmp(p, "c0", 2) == 0) + return parse_commitment_line(p + 3, host, host_len, + service, service_len, now, + rawkey); + + if (strncmp(p, "g0", 2) != 0) + return gnutls_assert_val(GNUTLS_E_PARSING_ERROR); + + /* read host */ + p = strtok_r(NULL, "|", &savep); + if (p == NULL) + return gnutls_assert_val(GNUTLS_E_PARSING_ERROR); + + if (p[0] != '*' && host != NULL && strcmp(p, host) != 0) + return gnutls_assert_val(GNUTLS_E_PARSING_ERROR); + + /* read service */ + p = strtok_r(NULL, "|", &savep); + if (p == NULL) + return gnutls_assert_val(GNUTLS_E_PARSING_ERROR); + + if (p[0] != '*' && service != NULL && strcmp(p, service) != 0) + return gnutls_assert_val(GNUTLS_E_PARSING_ERROR); + + /* read expiration */ + p = strtok_r(NULL, "|", &savep); + if (p == NULL) + return gnutls_assert_val(GNUTLS_E_PARSING_ERROR); + + expiration = (time_t) atol(p); + if (expiration > 0 && now > expiration) + return gnutls_assert_val(GNUTLS_E_EXPIRED); + + /* read key */ + kp = strtok_r(NULL, "|", &savep); + if (kp == NULL) + return gnutls_assert_val(GNUTLS_E_PARSING_ERROR); + + p = strpbrk(kp, "\n \r\t|"); + if (p != NULL) + *p = 0; + + kp_len = strlen(kp); + if (kp_len != b64key->size) + return + gnutls_assert_val(GNUTLS_E_CERTIFICATE_KEY_MISMATCH); + + if (memcmp(kp, b64key->data, b64key->size) != 0) + return + gnutls_assert_val(GNUTLS_E_CERTIFICATE_KEY_MISMATCH); + + /* key found and matches */ + return 0; +} + +/* Returns the base64 key if found + */ +static int verify_pubkey(const char *file, + const char *host, const char *service, + const gnutls_datum_t * pubkey) +{ + FILE *fp; + char *line = NULL; + size_t line_size = 0; + int ret, l2, mismatch = 0; + size_t host_len = 0, service_len = 0; + time_t now = gnutls_time(0); + gnutls_datum_t b64key = { NULL, 0 }; + + ret = raw_pubkey_to_base64(pubkey, &b64key); + if (ret < 0) + return gnutls_assert_val(ret); + + if (host != NULL) + host_len = strlen(host); + if (service != NULL) + service_len = strlen(service); + + fp = fopen(file, "rbe"); + if (fp == NULL) { + ret = gnutls_assert_val(GNUTLS_E_FILE_ERROR); + goto cleanup; + } + + do { + l2 = getline(&line, &line_size, fp); + if (l2 > 0) { + ret = + parse_line(line, host, host_len, service, + service_len, now, pubkey, &b64key); + if (ret == 0) { /* found */ + goto cleanup; + } else if (ret == + GNUTLS_E_CERTIFICATE_KEY_MISMATCH) + mismatch = 1; + } + } + while (l2 >= 0); + + if (mismatch) + ret = GNUTLS_E_CERTIFICATE_KEY_MISMATCH; + else + ret = GNUTLS_E_NO_CERTIFICATE_FOUND; + + cleanup: + free(line); + if (fp != NULL) + fclose(fp); + gnutls_free(b64key.data); + + return ret; +} + +static int raw_pubkey_to_base64(const gnutls_datum_t * raw, + gnutls_datum_t * b64) +{ + size_t size; + + size = BASE64_ENCODE_RAW_LENGTH(raw->size); + + b64->data = gnutls_malloc(size); + if (b64->data == NULL) + return gnutls_assert_val(GNUTLS_E_MEMORY_ERROR); + + base64_encode_raw((void*)b64->data, raw->size, raw->data); + b64->size = size; + + return 0; +} + +static +int store_pubkey(const char *db_name, const char *host, + const char *service, time_t expiration, + const gnutls_datum_t * pubkey) +{ + FILE *fp = NULL; + gnutls_datum_t b64key = { NULL, 0 }; + int ret; + + ret = gnutls_static_mutex_lock(&file_mutex); + if (ret != 0) + return gnutls_assert_val(GNUTLS_E_LOCKING_ERROR); + + ret = raw_pubkey_to_base64(pubkey, &b64key); + if (ret < 0) { + gnutls_assert(); + goto cleanup; + } + + fp = fopen(db_name, "abe+"); + if (fp == NULL) { + ret = gnutls_assert_val(GNUTLS_E_FILE_ERROR); + goto cleanup; + } + + if (service == NULL) + service = "*"; + if (host == NULL) + host = "*"; + + fprintf(fp, "|g0|%s|%s|%lu|%.*s\n", host, service, + (unsigned long) expiration, b64key.size, b64key.data); + + ret = 0; + + cleanup: + if (fp != NULL) + fclose(fp); + + (void)gnutls_static_mutex_unlock(&file_mutex); + gnutls_free(b64key.data); + + return ret; +} + +static +int store_commitment(const char *db_name, const char *host, + const char *service, time_t expiration, + gnutls_digest_algorithm_t hash_algo, + const gnutls_datum_t * hash) +{ + FILE *fp; + char buffer[MAX_HASH_SIZE * 2 + 1]; + + fp = fopen(db_name, "abe+"); + if (fp == NULL) + return gnutls_assert_val(GNUTLS_E_FILE_ERROR); + + if (service == NULL) + service = "*"; + if (host == NULL) + host = "*"; + + fprintf(fp, "|c0|%s|%s|%lu|%u|%s\n", host, service, + (unsigned long) expiration, (unsigned) hash_algo, + _gnutls_bin2hex(hash->data, hash->size, buffer, + sizeof(buffer), NULL)); + + fclose(fp); + + return 0; +} + +/** + * gnutls_store_pubkey: + * @db_name: A file specifying the stored keys (use NULL for the default) + * @tdb: A storage structure or NULL to use the default + * @host: The peer's name + * @service: non-NULL if this key is specific to a service (e.g. http) + * @cert_type: The type of the certificate + * @cert: The data of the certificate + * @expiration: The expiration time (use 0 to disable expiration) + * @flags: should be 0. + * + * This function will store a raw public-key or a public-key provided via + * a raw (DER-encoded) certificate to the list of stored public keys. The key + * will be considered valid until the provided expiration time. + * + * The @tdb variable if non-null specifies a custom backend for + * the storage of entries. If it is NULL then the + * default file backend will be used. + * + * Unless an alternative @tdb is provided, the storage format is a textual format + * consisting of a line for each host with fields separated by '|'. The contents of + * the fields are a format-identifier which is set to 'g0', the hostname that the + * rest of the data applies to, the numeric port or host name, the expiration + * time in seconds since the epoch (0 for no expiration), and a base64 + * encoding of the raw (DER) public key information (SPKI) of the peer. + * + * As of GnuTLS 3.6.6 this function also accepts raw public keys. + * + * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a + * negative error value. + * + * Since: 3.0.13 + **/ +int +gnutls_store_pubkey(const char *db_name, + gnutls_tdb_t tdb, + const char *host, + const char *service, + gnutls_certificate_type_t cert_type, + const gnutls_datum_t * cert, + time_t expiration, unsigned int flags) +{ + gnutls_datum_t pubkey = { NULL, 0 }; // Holds the pubkey in subjectPublicKeyInfo format (DER encoded) + int ret; + char local_file[MAX_FILENAME]; + bool need_free; + + + if (db_name == NULL && tdb == NULL) { + ret = + _gnutls_find_config_path(local_file, + sizeof(local_file)); + if (ret < 0) + return gnutls_assert_val(ret); + + _gnutls_debug_log("Configuration path: %s\n", local_file); + mkdir(local_file, 0700); + + ret = find_config_file(local_file, sizeof(local_file)); + if (ret < 0) + return gnutls_assert_val(ret); + db_name = local_file; + } + + if (tdb == NULL) + tdb = &default_tdb; + + /* Import the public key depending on the provided certificate type */ + switch (cert_type) { + case GNUTLS_CRT_X509: + /* Extract the pubkey from the cert. This function does a malloc + * deep down the call chain. We are responsible for freeing. */ + ret = _gnutls_x509_raw_crt_to_raw_pubkey(cert, &pubkey); + + if (ret < 0) { + _gnutls_free_datum(&pubkey); + return gnutls_assert_val(ret); + } + + need_free = true; + break; + case GNUTLS_CRT_RAWPK: + pubkey.data = cert->data; + pubkey.size = cert->size; + need_free = false; + break; + default: + return gnutls_assert_val(GNUTLS_E_UNSUPPORTED_CERTIFICATE_TYPE); + } + + _gnutls_debug_log("Configuration file: %s\n", db_name); + + ret = tdb->store(db_name, host, service, expiration, &pubkey); + + if (need_free) { + _gnutls_free_datum(&pubkey); + } + + if (ret < 0) { + return gnutls_assert_val(GNUTLS_E_DB_ERROR); + } + + return GNUTLS_E_SUCCESS; +} + +/** + * gnutls_store_commitment: + * @db_name: A file specifying the stored keys (use NULL for the default) + * @tdb: A storage structure or NULL to use the default + * @host: The peer's name + * @service: non-NULL if this key is specific to a service (e.g. http) + * @hash_algo: The hash algorithm type + * @hash: The raw hash + * @expiration: The expiration time (use 0 to disable expiration) + * @flags: should be 0 or %GNUTLS_SCOMMIT_FLAG_ALLOW_BROKEN. + * + * This function will store the provided hash commitment to + * the list of stored public keys. The key with the given + * hash will be considered valid until the provided expiration time. + * + * The @tdb variable if non-null specifies a custom backend for + * the storage of entries. If it is NULL then the + * default file backend will be used. + * + * Note that this function is not thread safe with the default backend. + * + * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a + * negative error value. + * + * Since: 3.0 + **/ +int +gnutls_store_commitment(const char *db_name, + gnutls_tdb_t tdb, + const char *host, + const char *service, + gnutls_digest_algorithm_t hash_algo, + const gnutls_datum_t * hash, + time_t expiration, unsigned int flags) +{ + int ret; + char local_file[MAX_FILENAME]; + const mac_entry_st *me = hash_to_entry(hash_algo); + + if (me == NULL) + return gnutls_assert_val(GNUTLS_E_ILLEGAL_PARAMETER); + + if (!(flags & GNUTLS_SCOMMIT_FLAG_ALLOW_BROKEN) && _gnutls_digest_is_secure(me) == 0) + return gnutls_assert_val(GNUTLS_E_INSUFFICIENT_SECURITY); + + if (_gnutls_hash_get_algo_len(me) != hash->size) + return gnutls_assert_val(GNUTLS_E_INVALID_REQUEST); + + if (db_name == NULL && tdb == NULL) { + ret = + _gnutls_find_config_path(local_file, + sizeof(local_file)); + if (ret < 0) + return gnutls_assert_val(ret); + + _gnutls_debug_log("Configuration path: %s\n", local_file); + mkdir(local_file, 0700); + + ret = find_config_file(local_file, sizeof(local_file)); + if (ret < 0) + return gnutls_assert_val(ret); + db_name = local_file; + } + + if (tdb == NULL) + tdb = &default_tdb; + + _gnutls_debug_log("Configuration file: %s\n", db_name); + + ret = tdb->cstore(db_name, host, service, expiration, + (gnutls_digest_algorithm_t)me->id, hash); + if (ret < 0) { + return gnutls_assert_val(GNUTLS_E_DB_ERROR); + } + + return 0; +} + +#define CONFIG_FILE "known_hosts" + +static int find_config_file(char *file, size_t max_size) +{ + char path[MAX_FILENAME]; + int ret; + + ret = _gnutls_find_config_path(path, sizeof(path)); + if (ret < 0) + return gnutls_assert_val(ret); + + if (path[0] == 0) + snprintf(file, max_size, "%s", CONFIG_FILE); + else + snprintf(file, max_size, "%s/%s", path, CONFIG_FILE); + + return 0; +} + +/** + * gnutls_tdb_init: + * @tdb: A pointer to the type to be initialized + * + * This function will initialize a public key trust storage structure. + * + * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a + * negative error value. + **/ +int gnutls_tdb_init(gnutls_tdb_t * tdb) +{ + *tdb = gnutls_calloc(1, sizeof(struct gnutls_tdb_int)); + + if (!*tdb) + return GNUTLS_E_MEMORY_ERROR; + + return 0; +} + +/** + * gnutls_set_store_func: + * @tdb: The trust storage + * @store: The storage function + * + * This function will associate a storage function with the + * trust storage structure. The function is of the following form. + * + * int gnutls_tdb_store_func(const char* db_name, const char* host, + * const char* service, time_t expiration, + * const gnutls_datum_t* pubkey); + * + * The @db_name should be used to pass any private data to this function. + * + **/ +void gnutls_tdb_set_store_func(gnutls_tdb_t tdb, + gnutls_tdb_store_func store) +{ + tdb->store = store; +} + +/** + * gnutls_set_store_commitment_func: + * @tdb: The trust storage + * @cstore: The commitment storage function + * + * This function will associate a commitment (hash) storage function with the + * trust storage structure. The function is of the following form. + * + * int gnutls_tdb_store_commitment_func(const char* db_name, const char* host, + * const char* service, time_t expiration, + * gnutls_digest_algorithm_t, const gnutls_datum_t* hash); + * + * The @db_name should be used to pass any private data to this function. + * + **/ +void gnutls_tdb_set_store_commitment_func(gnutls_tdb_t tdb, + gnutls_tdb_store_commitment_func + cstore) +{ + tdb->cstore = cstore; +} + +/** + * gnutls_set_verify_func: + * @tdb: The trust storage + * @verify: The verification function + * + * This function will associate a retrieval function with the + * trust storage structure. The function is of the following form. + * + * int gnutls_tdb_verify_func(const char* db_name, const char* host, + * const char* service, const gnutls_datum_t* pubkey); + * + * The verify function should return zero on a match, %GNUTLS_E_CERTIFICATE_KEY_MISMATCH + * if there is a mismatch and any other negative error code otherwise. + * + * The @db_name should be used to pass any private data to this function. + * + **/ +void gnutls_tdb_set_verify_func(gnutls_tdb_t tdb, + gnutls_tdb_verify_func verify) +{ + tdb->verify = verify; +} + +/** + * gnutls_tdb_deinit: + * @tdb: The structure to be deinitialized + * + * This function will deinitialize a public key trust storage structure. + **/ +void gnutls_tdb_deinit(gnutls_tdb_t tdb) +{ + gnutls_free(tdb); +} |