tinc-vpn.org Git - tinc/blob - src/protocol_key.c

   1 /*
   2     protocol_key.c -- handle the meta-protocol, key exchange
   3     Copyright (C) 1999-2005 Ivo Timmermans,
   4                   2000-2012 Guus Sliepen <guus@tinc-vpn.org>
   5
   6     This program is free software; you can redistribute it and/or modify
   7     it under the terms of the GNU General Public License as published by
   8     the Free Software Foundation; either version 2 of the License, or
   9     (at your option) any later version.
  10
  11     This program is distributed in the hope that it will be useful,
  12     but WITHOUT ANY WARRANTY; without even the implied warranty of
  13     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14     GNU General Public License for more details.
  15
  16     You should have received a copy of the GNU General Public License along
  17     with this program; if not, write to the Free Software Foundation, Inc.,
  18     51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  19 */
  20
  21 #include "system.h"
  22
  23 #include "splay_tree.h"
  24 #include "cipher.h"
  25 #include "connection.h"
  26 #include "crypto.h"
  27 #include "logger.h"
  28 #include "net.h"
  29 #include "netutl.h"
  30 #include "node.h"
  31 #include "prf.h"
  32 #include "protocol.h"
  33 #include "sptps.h"
  34 #include "utils.h"
  35 #include "xalloc.h"
  36
  37 static bool mykeyused = false;
  38
  39 void send_key_changed(void) {
  40         splay_node_t *node;
  41         connection_t *c;
  42
  43         send_request(everyone, "%d %x %s", KEY_CHANGED, rand(), myself->name);
  44
  45         /* Immediately send new keys to directly connected nodes to keep UDP mappings alive */
  46
  47         for(node = connection_tree->head; node; node = node->next) {
  48                 c = node->data;
  49                 if(c->status.active && c->node && c->node->status.reachable) {
  50                         if(!experimental || OPTION_VERSION(c->node->options) < 2)
  51                                 send_ans_key(c->node);
  52                 }
  53         }
  54
  55         /* Force key exchange for connections using SPTPS */
  56
  57         if(experimental) {
  58                 for(node = node_tree->head; node; node = node->next) {
  59                         node_t *n = node->data;
  60                         if(n->status.reachable && n->status.validkey && OPTION_VERSION(n->options) >= 2)
  61                                 sptps_force_kex(&n->sptps);
  62                 }
  63         }
  64 }
  65
  66 bool key_changed_h(connection_t *c, const char *request) {
  67         char name[MAX_STRING_SIZE];
  68         node_t *n;
  69
  70         if(sscanf(request, "%*d %*x " MAX_STRING, name) != 1) {
  71                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s)", "KEY_CHANGED",
  72                            c->name, c->hostname);
  73                 return false;
  74         }
  75
  76         if(seen_request(request))
  77                 return true;
  78
  79         n = lookup_node(name);
  80
  81         if(!n) {
  82                 logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) origin %s which does not exist",
  83                            "KEY_CHANGED", c->name, c->hostname, name);
  84                 return true;
  85         }
  86
  87         if(OPTION_VERSION(n->options) < 2) {
  88                 n->status.validkey = false;
  89                 n->last_req_key = 0;
  90         }
  91
  92         /* Tell the others */
  93
  94         if(!tunnelserver)
  95                 forward_request(c, request);
  96
  97         return true;
  98 }
  99
 100 static bool send_initial_sptps_data(void *handle, uint8_t type, const char *data, size_t len) {
 101         node_t *to = handle;
 102         to->sptps.send_data = send_sptps_data;
 103         char buf[len * 4 / 3 + 5];
 104         b64encode(data, buf, len);
 105         return send_request(to->nexthop->connection, "%d %s %s %d %s", REQ_KEY, myself->name, to->name, REQ_KEY, buf);
 106 }
 107
 108 bool send_req_key(node_t *to) {
 109         if(experimental && OPTION_VERSION(to->options) >= 2) {
 110                 if(!node_read_ecdsa_public_key(to)) {
 111                         logger(DEBUG_ALWAYS, LOG_DEBUG, "No ECDSA key known for %s (%s)", to->name, to->hostname);
 112                         send_request(to->nexthop->connection, "%d %s %s %d", REQ_KEY, myself->name, to->name, REQ_PUBKEY);
 113                         return true;
 114                 }
 115                 char label[25 + strlen(myself->name) + strlen(to->name)];
 116                 snprintf(label, sizeof label, "tinc UDP key expansion %s %s", myself->name, to->name);
 117                 return sptps_start(&to->sptps, to, true, true, myself->connection->ecdsa, to->ecdsa, label, sizeof label, send_initial_sptps_data, receive_sptps_record);
 118         }
 119
 120         return send_request(to->nexthop->connection, "%d %s %s", REQ_KEY, myself->name, to->name);
 121 }
 122
 123 /* REQ_KEY is overloaded to allow arbitrary requests to be routed between two nodes. */
 124
 125 static bool req_key_ext_h(connection_t *c, const char *request, node_t *from, int reqno) {
 126         switch(reqno) {
 127                 case REQ_PUBKEY: {
 128                         char *pubkey = ecdsa_get_base64_public_key(&myself->connection->ecdsa);
 129                         send_request(from->nexthop->connection, "%d %s %s %d %s", REQ_KEY, myself->name, from->name, ANS_PUBKEY, pubkey);
 130                         free(pubkey);
 131                         return true;
 132                 }
 133
 134                 case ANS_PUBKEY: {
 135                         if(node_read_ecdsa_public_key(from)) {
 136                                 logger(DEBUG_ALWAYS, LOG_WARNING, "Got ANS_PUBKEY from %s (%s) even though we already have his pubkey", from->name, from->hostname);
 137                                 return true;
 138                         }
 139
 140                         char pubkey[MAX_STRING_SIZE];
 141                         if(sscanf(request, "%*d %*s %*s %*d " MAX_STRING, pubkey) != 1 || !ecdsa_set_base64_public_key(&from->ecdsa, pubkey)) {
 142                                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "ANS_PUBKEY", from->name, from->hostname, "invalid pubkey");
 143                                 return true;
 144                         }
 145
 146                         logger(DEBUG_ALWAYS, LOG_INFO, "Learned ECDSA public key from %s (%s)", from->name, from->hostname);
 147                         append_config_file(from->name, "ECDSAPublicKey", pubkey);
 148                         return true;
 149                 }
 150
 151                 case REQ_KEY: {
 152                         if(!node_read_ecdsa_public_key(from)) {
 153                                 logger(DEBUG_ALWAYS, LOG_DEBUG, "No ECDSA key known for %s (%s)", from->name, from->hostname);
 154                                 send_request(from->nexthop->connection, "%d %s %s %d", REQ_KEY, myself->name, from->name, REQ_PUBKEY);
 155                                 return true;
 156                         }
 157                 }
 158
 159                 case REQ_SPTPS: {
 160                         char buf[MAX_STRING_SIZE];
 161                         if(sscanf(request, "%*d %*s %*s %*d " MAX_STRING, buf) != 1) {
 162                                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "REQ_KEY", from->name, from->hostname, "invalid SPTPS data");
 163                                 return true;
 164                         }
 165                         int len = b64decode(buf, buf, strlen(buf));
 166
 167
 168                         char label[25 + strlen(from->name) + strlen(myself->name)];
 169                         snprintf(label, sizeof label, "tinc UDP key expansion %s %s", from->name, myself->name);
 170                         sptps_start(&from->sptps, from, false, true, myself->connection->ecdsa, from->ecdsa, label, sizeof label, send_sptps_data, receive_sptps_record);
 171                         sptps_receive_data(&from->sptps, buf, len);
 172                         return true;
 173                 }
 174
 175                 default:
 176                         logger(DEBUG_ALWAYS, LOG_ERR, "Unknown extended REQ_KEY request from %s (%s): %s", from->name, from->hostname, request);
 177                         return true;
 178         }
 179 }
 180
 181 bool req_key_h(connection_t *c, const char *request) {
 182         char from_name[MAX_STRING_SIZE];
 183         char to_name[MAX_STRING_SIZE];
 184         node_t *from, *to;
 185         int reqno = 0;
 186
 187         if(sscanf(request, "%*d " MAX_STRING " " MAX_STRING " %d", from_name, to_name, &reqno) < 2) {
 188                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s)", "REQ_KEY", c->name,
 189                            c->hostname);
 190                 return false;
 191         }
 192
 193         if(!check_id(from_name) || !check_id(to_name)) {
 194                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "REQ_KEY", c->name, c->hostname, "invalid name");
 195                 return false;
 196         }
 197
 198         from = lookup_node(from_name);
 199
 200         if(!from) {
 201                 logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) origin %s which does not exist in our connection list",
 202                            "REQ_KEY", c->name, c->hostname, from_name);
 203                 return true;
 204         }
 205
 206         to = lookup_node(to_name);
 207
 208         if(!to) {
 209                 logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) destination %s which does not exist in our connection list",
 210                            "REQ_KEY", c->name, c->hostname, to_name);
 211                 return true;
 212         }
 213
 214         /* Check if this key request is for us */
 215
 216         if(to == myself) {                      /* Yes, send our own key back */
 217                 if(experimental && reqno)
 218                         return req_key_ext_h(c, request, from, reqno);
 219
 220                 send_ans_key(from);
 221         } else {
 222                 if(tunnelserver)
 223                         return true;
 224
 225                 if(!to->status.reachable) {
 226                         logger(DEBUG_ALWAYS, LOG_WARNING, "Got %s from %s (%s) destination %s which is not reachable",
 227                                 "REQ_KEY", c->name, c->hostname, to_name);
 228                         return true;
 229                 }
 230
 231                 send_request(to->nexthop->connection, "%s", request);
 232         }
 233
 234         return true;
 235 }
 236
 237 bool send_ans_key(node_t *to) {
 238         if(experimental && OPTION_VERSION(to->options) >= 2)
 239                 abort();
 240
 241         size_t keylen = cipher_keylength(&myself->incipher);
 242         char key[keylen * 2 + 1];
 243
 244         cipher_open_by_nid(&to->incipher, cipher_get_nid(&myself->incipher));
 245         digest_open_by_nid(&to->indigest, digest_get_nid(&myself->indigest), digest_length(&myself->indigest));
 246         to->incompression = myself->incompression;
 247
 248         randomize(key, keylen);
 249         cipher_set_key(&to->incipher, key, false);
 250         digest_set_key(&to->indigest, key, keylen);
 251
 252         bin2hex(key, key, keylen);
 253
 254         // Reset sequence number and late packet window
 255         mykeyused = true;
 256         to->received_seqno = 0;
 257         if(replaywin) memset(to->late, 0, replaywin);
 258
 259         return send_request(to->nexthop->connection, "%d %s %s %s %d %d %d %d", ANS_KEY,
 260                                                 myself->name, to->name, key,
 261                                                 cipher_get_nid(&to->incipher),
 262                                                 digest_get_nid(&to->indigest),
 263                                                 (int)digest_length(&to->indigest),
 264                                                 to->incompression);
 265 }
 266
 267 bool ans_key_h(connection_t *c, const char *request) {
 268         char from_name[MAX_STRING_SIZE];
 269         char to_name[MAX_STRING_SIZE];
 270         char key[MAX_STRING_SIZE];
 271         char address[MAX_STRING_SIZE] = "";
 272         char port[MAX_STRING_SIZE] = "";
 273         int cipher, digest, maclength, compression, keylen;
 274         node_t *from, *to;
 275
 276         if(sscanf(request, "%*d "MAX_STRING" "MAX_STRING" "MAX_STRING" %d %d %d %d "MAX_STRING" "MAX_STRING,
 277                 from_name, to_name, key, &cipher, &digest, &maclength,
 278                 &compression, address, port) < 7) {
 279                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s)", "ANS_KEY", c->name,
 280                            c->hostname);
 281                 return false;
 282         }
 283
 284         if(!check_id(from_name) || !check_id(to_name)) {
 285                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "ANS_KEY", c->name, c->hostname, "invalid name");
 286                 return false;
 287         }
 288
 289         from = lookup_node(from_name);
 290
 291         if(!from) {
 292                 logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) origin %s which does not exist in our connection list",
 293                            "ANS_KEY", c->name, c->hostname, from_name);
 294                 return true;
 295         }
 296
 297         to = lookup_node(to_name);
 298
 299         if(!to) {
 300                 logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) destination %s which does not exist in our connection list",
 301                            "ANS_KEY", c->name, c->hostname, to_name);
 302                 return true;
 303         }
 304
 305         /* Forward it if necessary */
 306
 307         if(to != myself) {
 308                 if(tunnelserver)
 309                         return true;
 310
 311                 if(!to->status.reachable) {
 312                         logger(DEBUG_ALWAYS, LOG_WARNING, "Got %s from %s (%s) destination %s which is not reachable",
 313                                    "ANS_KEY", c->name, c->hostname, to_name);
 314                         return true;
 315                 }
 316
 317                 if(!*address && from->address.sa.sa_family != AF_UNSPEC) {
 318                         char *address, *port;
 319                         logger(DEBUG_PROTOCOL, LOG_DEBUG, "Appending reflexive UDP address to ANS_KEY from %s to %s", from->name, to->name);
 320                         sockaddr2str(&from->address, &address, &port);
 321                         send_request(to->nexthop->connection, "%s %s %s", request, address, port);
 322                         free(address);
 323                         free(port);
 324                         return true;
 325                 }
 326
 327                 return send_request(to->nexthop->connection, "%s", request);
 328         }
 329
 330         /* SPTPS or old-style key exchange? */
 331
 332         if(experimental && OPTION_VERSION(from->options) >= 2) {
 333                 char buf[strlen(key)];
 334                 int len = b64decode(key, buf, strlen(key));
 335
 336                 if(!sptps_receive_data(&from->sptps, buf, len))
 337                         logger(DEBUG_ALWAYS, LOG_ERR, "Error processing SPTPS data from %s (%s)", from->name, from->hostname);
 338
 339                 if(from->status.validkey) {
 340                         if(*address && *port) {
 341                                 logger(DEBUG_PROTOCOL, LOG_DEBUG, "Using reflexive UDP address from %s: %s port %s", from->name, address, port);
 342                                 sockaddr_t sa = str2sockaddr(address, port);
 343                                 update_node_udp(from, &sa);
 344                         }
 345
 346                         if(from->options & OPTION_PMTU_DISCOVERY)
 347                                 send_mtu_probe(from);
 348                 }
 349
 350                 return true;
 351         }
 352
 353         /* Check and lookup cipher and digest algorithms */
 354
 355         if(!cipher_open_by_nid(&from->outcipher, cipher)) {
 356                 logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses unknown cipher!", from->name, from->hostname);
 357                 return false;
 358         }
 359
 360         if(!digest_open_by_nid(&from->outdigest, digest, maclength)) {
 361                 logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses unknown digest!", from->name, from->hostname);
 362                 return false;
 363         }
 364
 365         if(maclength != digest_length(&from->outdigest)) {
 366                 logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses bogus MAC length!", from->name, from->hostname);
 367                 return false;
 368         }
 369
 370         if(compression < 0 || compression > 11) {
 371                 logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses bogus compression level!", from->name, from->hostname);
 372                 return true;
 373         }
 374
 375         from->outcompression = compression;
 376
 377         /* Process key */
 378
 379         keylen = hex2bin(key, key, sizeof key);
 380
 381         if(keylen != cipher_keylength(&from->outcipher)) {
 382                 logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses wrong keylength!", from->name, from->hostname);
 383                 return true;
 384         }
 385
 386         /* Update our copy of the origin's packet key */
 387
 388         cipher_set_key(&from->outcipher, key, true);
 389         digest_set_key(&from->outdigest, key, keylen);
 390
 391         from->status.validkey = true;
 392         from->sent_seqno = 0;
 393
 394         if(*address && *port) {
 395                 logger(DEBUG_PROTOCOL, LOG_DEBUG, "Using reflexive UDP address from %s: %s port %s", from->name, address, port);
 396                 sockaddr_t sa = str2sockaddr(address, port);
 397                 update_node_udp(from, &sa);
 398         }
 399
 400         if(from->options & OPTION_PMTU_DISCOVERY)
 401                 send_mtu_probe(from);
 402
 403         return true;
 404 }