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-rw-r--r--keys.c413
1 files changed, 413 insertions, 0 deletions
diff --git a/keys.c b/keys.c
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+/*
+ chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow 1997-2003
+ * Copyright (C) Miroslav Lichvar 2012-2016
+ *
+ * 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 "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 struct {
+ uint32_t id;
+ char *val;
+ int len;
+ int hash_id;
+ int auth_delay;
+} 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;
+
+ for (i = 0; i < ARR_GetSize(keys); i++)
+ Free(((Key *)ARR_GetElement(keys, i))->val);
+
+ 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;
+}
+
+/* ================================================== */
+
+static int
+determine_hash_delay(uint32_t key_id)
+{
+ NTP_Packet pkt;
+ struct timespec before, after;
+ double diff, min_diff;
+ int i, nsecs;
+
+ memset(&pkt, 0, sizeof (pkt));
+
+ for (i = 0; i < 10; i++) {
+ LCL_ReadRawTime(&before);
+ KEY_GenerateAuth(key_id, (unsigned char *)&pkt, NTP_NORMAL_PACKET_LENGTH,
+ (unsigned char *)&pkt.auth_data, sizeof (pkt.auth_data));
+ LCL_ReadRawTime(&after);
+
+ diff = UTI_DiffTimespecsToDouble(&after, &before);
+
+ if (i == 0 || min_diff > diff)
+ min_diff = diff;
+ }
+
+ /* Add on a bit extra to allow for copying, conversions etc */
+ nsecs = 1.0625e9 * min_diff;
+
+ DEBUG_LOG("authentication delay for key %"PRIu32": %d nsecs", key_id, nsecs);
+
+ return nsecs;
+}
+
+/* ================================================== */
+/* Decode password encoded in ASCII or HEX */
+
+static int
+decode_password(char *key)
+{
+ int i, j, len = strlen(key);
+ char buf[3], *p;
+
+ if (!strncmp(key, "ASCII:", 6)) {
+ memmove(key, key + 6, len - 6);
+ return len - 6;
+ } else if (!strncmp(key, "HEX:", 4)) {
+ if ((len - 4) % 2)
+ return 0;
+
+ for (i = 0, j = 4; j + 1 < len; i++, j += 2) {
+ buf[0] = key[j], buf[1] = key[j + 1], buf[2] = '\0';
+ key[i] = strtol(buf, &p, 16);
+
+ if (p != buf + 2)
+ return 0;
+ }
+
+ return i;
+ } 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;
+ FILE *in;
+ uint32_t key_id;
+ char line[2048], *keyval, *key_file;
+ const char *hashname;
+ Key key;
+
+ free_keys();
+
+ key_file = CNF_GetKeysFile();
+ line_number = 0;
+
+ if (!key_file)
+ return;
+
+ in = fopen(key_file, "r");
+ 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;
+
+ if (!CPS_ParseKey(line, &key_id, &hashname, &keyval)) {
+ LOG(LOGS_WARN, "Could not parse key at line %u in file %s", line_number, key_file);
+ continue;
+ }
+
+ key.hash_id = HSH_GetHashId(hashname);
+ if (key.hash_id < 0) {
+ LOG(LOGS_WARN, "Unknown hash function in key %"PRIu32, key_id);
+ continue;
+ }
+
+ key.len = decode_password(keyval);
+ if (!key.len) {
+ LOG(LOGS_WARN, "Could not decode password in key %"PRIu32, key_id);
+ continue;
+ }
+
+ key.id = key_id;
+ key.val = MallocArray(char, key.len);
+ memcpy(key.val, keyval, key.len);
+ 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);
+
+ /* 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));
+
+ for (i = 0; i < ARR_GetSize(keys); i++)
+ get_key(i)->auth_delay = determine_hash_delay(get_key(i)->id);
+}
+
+/* ================================================== */
+
+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_GetAuthDelay(uint32_t key_id)
+{
+ Key *key;
+
+ key = get_key_by_id(key_id);
+
+ if (!key)
+ return 0;
+
+ return key->auth_delay;
+}
+
+/* ================================================== */
+
+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;
+
+ return HSH_Hash(key->hash_id, buf, 0, buf, 0, buf, sizeof (buf));
+}
+
+/* ================================================== */
+
+int
+KEY_CheckKeyLength(uint32_t key_id)
+{
+ Key *key;
+
+ key = get_key_by_id(key_id);
+
+ if (!key)
+ return 0;
+
+ return key->len >= MIN_SECURE_KEY_LENGTH;
+}
+
+/* ================================================== */
+
+static int
+generate_ntp_auth(int hash_id, const unsigned char *key, int key_len,
+ const unsigned char *data, int data_len,
+ unsigned char *auth, int auth_len)
+{
+ return HSH_Hash(hash_id, key, key_len, data, data_len, auth, auth_len);
+}
+
+/* ================================================== */
+
+static int
+check_ntp_auth(int hash_id, const unsigned char *key, int key_len,
+ const unsigned char *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_ntp_auth(hash_id, key, key_len, 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 unsigned char *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_ntp_auth(key->hash_id, (unsigned char *)key->val, key->len,
+ data, data_len, auth, auth_len);
+}
+
+/* ================================================== */
+
+int
+KEY_CheckAuth(uint32_t key_id, const unsigned char *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_ntp_auth(key->hash_id, (unsigned char *)key->val, key->len,
+ data, data_len, auth, auth_len, trunc_len);
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-23 07:13:43 +0000