From b2d2d555a704148968cb7e566735a2a1b1a2f189 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Tue, 9 Apr 2024 14:48:01 +0200 Subject: Adding upstream version 4.5. Signed-off-by: Daniel Baumann --- keys.c | 441 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 441 insertions(+) create mode 100644 keys.c (limited to 'keys.c') diff --git a/keys.c b/keys.c new file mode 100644 index 0000000..9225e6c --- /dev/null +++ b/keys.c @@ -0,0 +1,441 @@ +/* + chronyd/chronyc - Programs for keeping computer clocks accurate. + + ********************************************************************** + * Copyright (C) Richard P. Curnow 1997-2003 + * Copyright (C) Miroslav Lichvar 2012-2016, 2019-2020 + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of version 2 of the GNU General Public License as + * published by the Free Software Foundation. + * + * This program 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 + * General Public License for more details. + * + * You should have received a copy of the GNU General Public License along + * with this program; if not, write to the Free Software Foundation, Inc., + * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. + * + ********************************************************************** + + ======================================================================= + + Module for managing keys used for authenticating NTP packets and commands + + */ + +#include "config.h" + +#include "sysincl.h" + +#include "array.h" +#include "keys.h" +#include "cmac.h" +#include "cmdparse.h" +#include "conf.h" +#include "memory.h" +#include "util.h" +#include "local.h" +#include "logging.h" + +/* Consider 80 bits as the absolute minimum for a secure key */ +#define MIN_SECURE_KEY_LENGTH 10 + +typedef enum { + NTP_MAC, + CMAC, +} KeyClass; + +typedef struct { + uint32_t id; + int type; + int length; + KeyClass class; + union { + struct { + unsigned char *value; + int hash_id; + } ntp_mac; + CMC_Instance cmac; + } data; +} Key; + +static ARR_Instance keys; + +static int cache_valid; +static uint32_t cache_key_id; +static int cache_key_pos; + +/* ================================================== */ + +static void +free_keys(void) +{ + unsigned int i; + Key *key; + + for (i = 0; i < ARR_GetSize(keys); i++) { + key = ARR_GetElement(keys, i); + switch (key->class) { + case NTP_MAC: + Free(key->data.ntp_mac.value); + break; + case CMAC: + CMC_DestroyInstance(key->data.cmac); + break; + default: + assert(0); + } + } + + ARR_SetSize(keys, 0); + cache_valid = 0; +} + +/* ================================================== */ + +void +KEY_Initialise(void) +{ + keys = ARR_CreateInstance(sizeof (Key)); + cache_valid = 0; + KEY_Reload(); +} + +/* ================================================== */ + +void +KEY_Finalise(void) +{ + free_keys(); + ARR_DestroyInstance(keys); +} + +/* ================================================== */ + +static Key * +get_key(unsigned int index) +{ + return ((Key *)ARR_GetElements(keys)) + index; +} + +/* ================================================== */ +/* Decode key encoded in ASCII or HEX */ + +static int +decode_key(char *key) +{ + int len = strlen(key); + + if (!strncmp(key, "ASCII:", 6)) { + memmove(key, key + 6, len - 6); + return len - 6; + } else if (!strncmp(key, "HEX:", 4)) { + return UTI_HexToBytes(key + 4, key, len); + } else { + /* assume ASCII */ + return len; + } +} + +/* ================================================== */ + +/* Compare two keys */ + +static int +compare_keys_by_id(const void *a, const void *b) +{ + const Key *c = (const Key *) a; + const Key *d = (const Key *) b; + + if (c->id < d->id) { + return -1; + } else if (c->id > d->id) { + return +1; + } else { + return 0; + } + +} + +/* ================================================== */ + +void +KEY_Reload(void) +{ + unsigned int i, line_number, key_length, cmac_key_length; + FILE *in; + char line[2048], *key_file, *key_value; + const char *key_type; + HSH_Algorithm hash_algorithm; + CMC_Algorithm cmac_algorithm; + int hash_id; + Key key; + + free_keys(); + + key_file = CNF_GetKeysFile(); + line_number = 0; + + if (!key_file) + return; + + if (!UTI_CheckFilePermissions(key_file, 0771)) + ; + + in = UTI_OpenFile(NULL, key_file, NULL, 'r', 0); + if (!in) { + LOG(LOGS_WARN, "Could not open keyfile %s", key_file); + return; + } + + while (fgets(line, sizeof (line), in)) { + line_number++; + + CPS_NormalizeLine(line); + if (!*line) + continue; + + memset(&key, 0, sizeof (key)); + + if (!CPS_ParseKey(line, &key.id, &key_type, &key_value)) { + LOG(LOGS_WARN, "Could not parse key at line %u in file %s", line_number, key_file); + continue; + } + + key_length = decode_key(key_value); + if (key_length == 0) { + LOG(LOGS_WARN, "Could not decode key %"PRIu32, key.id); + continue; + } + + hash_algorithm = UTI_HashNameToAlgorithm(key_type); + cmac_algorithm = UTI_CmacNameToAlgorithm(key_type); + + if (hash_algorithm != 0) { + hash_id = HSH_GetHashId(hash_algorithm); + if (hash_id < 0) { + LOG(LOGS_WARN, "Unsupported %s in key %"PRIu32, "hash function", key.id); + continue; + } + key.class = NTP_MAC; + key.type = hash_algorithm; + key.length = key_length; + key.data.ntp_mac.value = MallocArray(unsigned char, key_length); + memcpy(key.data.ntp_mac.value, key_value, key_length); + key.data.ntp_mac.hash_id = hash_id; + } else if (cmac_algorithm != 0) { + cmac_key_length = CMC_GetKeyLength(cmac_algorithm); + if (cmac_key_length == 0) { + LOG(LOGS_WARN, "Unsupported %s in key %"PRIu32, "cipher", key.id); + continue; + } else if (cmac_key_length != key_length) { + LOG(LOGS_WARN, "Invalid length of %s key %"PRIu32" (expected %u bits)", + key_type, key.id, 8 * cmac_key_length); + continue; + } + + key.class = CMAC; + key.type = cmac_algorithm; + key.length = key_length; + key.data.cmac = CMC_CreateInstance(cmac_algorithm, (unsigned char *)key_value, + key_length); + assert(key.data.cmac); + } else { + LOG(LOGS_WARN, "Invalid type in key %"PRIu32, key.id); + continue; + } + + ARR_AppendElement(keys, &key); + } + + fclose(in); + + /* Sort keys into order. Note, if there's a duplicate, it is + arbitrary which one we use later - the user should have been + more careful! */ + qsort(ARR_GetElements(keys), ARR_GetSize(keys), sizeof (Key), compare_keys_by_id); + + LOG(LOGS_INFO, "Loaded %u symmetric keys", ARR_GetSize(keys)); + + /* Check for duplicates */ + for (i = 1; i < ARR_GetSize(keys); i++) { + if (get_key(i - 1)->id == get_key(i)->id) + LOG(LOGS_WARN, "Detected duplicate key %"PRIu32, get_key(i - 1)->id); + } + + /* Erase any passwords from stack */ + memset(line, 0, sizeof (line)); +} + +/* ================================================== */ + +static int +lookup_key(uint32_t id) +{ + Key specimen, *where, *keys_ptr; + int pos; + + keys_ptr = ARR_GetElements(keys); + specimen.id = id; + where = (Key *)bsearch((void *)&specimen, keys_ptr, ARR_GetSize(keys), + sizeof (Key), compare_keys_by_id); + if (!where) { + return -1; + } else { + pos = where - keys_ptr; + return pos; + } +} + +/* ================================================== */ + +static Key * +get_key_by_id(uint32_t key_id) +{ + int position; + + if (cache_valid && key_id == cache_key_id) + return get_key(cache_key_pos); + + position = lookup_key(key_id); + + if (position >= 0) { + cache_valid = 1; + cache_key_pos = position; + cache_key_id = key_id; + + return get_key(position); + } + + return NULL; +} + +/* ================================================== */ + +int +KEY_KeyKnown(uint32_t key_id) +{ + return get_key_by_id(key_id) != NULL; +} + +/* ================================================== */ + +int +KEY_GetAuthLength(uint32_t key_id) +{ + unsigned char buf[MAX_HASH_LENGTH]; + Key *key; + + key = get_key_by_id(key_id); + + if (!key) + return 0; + + switch (key->class) { + case NTP_MAC: + return HSH_Hash(key->data.ntp_mac.hash_id, buf, 0, buf, 0, buf, sizeof (buf)); + case CMAC: + return CMC_Hash(key->data.cmac, buf, 0, buf, sizeof (buf)); + default: + assert(0); + return 0; + } +} + +/* ================================================== */ + +int +KEY_CheckKeyLength(uint32_t key_id) +{ + Key *key; + + key = get_key_by_id(key_id); + + if (!key) + return 0; + + return key->length >= MIN_SECURE_KEY_LENGTH; +} + +/* ================================================== */ + +int +KEY_GetKeyInfo(uint32_t key_id, int *type, int *bits) +{ + Key *key; + + key = get_key_by_id(key_id); + + if (!key) + return 0; + + *type = key->type; + *bits = 8 * key->length; + + return 1; +} + +/* ================================================== */ + +static int +generate_auth(Key *key, const void *data, int data_len, unsigned char *auth, int auth_len) +{ + switch (key->class) { + case NTP_MAC: + return HSH_Hash(key->data.ntp_mac.hash_id, key->data.ntp_mac.value, + key->length, data, data_len, auth, auth_len); + case CMAC: + return CMC_Hash(key->data.cmac, data, data_len, auth, auth_len); + default: + return 0; + } +} + +/* ================================================== */ + +static int +check_auth(Key *key, const void *data, int data_len, + const unsigned char *auth, int auth_len, int trunc_len) +{ + unsigned char buf[MAX_HASH_LENGTH]; + int hash_len; + + hash_len = generate_auth(key, data, data_len, buf, sizeof (buf)); + + return MIN(hash_len, trunc_len) == auth_len && !memcmp(buf, auth, auth_len); +} + +/* ================================================== */ + +int +KEY_GenerateAuth(uint32_t key_id, const void *data, int data_len, + unsigned char *auth, int auth_len) +{ + Key *key; + + key = get_key_by_id(key_id); + + if (!key) + return 0; + + return generate_auth(key, data, data_len, auth, auth_len); +} + +/* ================================================== */ + +int +KEY_CheckAuth(uint32_t key_id, const void *data, int data_len, + const unsigned char *auth, int auth_len, int trunc_len) +{ + Key *key; + + key = get_key_by_id(key_id); + + if (!key) + return 0; + + return check_auth(key, data, data_len, auth, auth_len, trunc_len); +} -- cgit v1.2.3