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                   2000-2014 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 "cipher.h"
  24 #include "connection.h"
  25 #include "crypto.h"
  26 #include "logger.h"
  27 #include "net.h"
  28 #include "netutl.h"
  29 #include "node.h"
  30 #include "prf.h"
  31 #include "protocol.h"
  32 #include "sptps.h"
  33 #include "utils.h"
  34 #include "xalloc.h"
  35
  36 static bool mykeyused = false;
  37
  38 void send_key_changed(void) {
  39 #ifndef DISABLE_LEGACY
  40         send_request(everyone, "%d %x %s", KEY_CHANGED, rand(), myself->name);
  41
  42         /* Immediately send new keys to directly connected nodes to keep UDP mappings alive */
  43
  44         for list_each(connection_t, c, connection_list)
  45                 if(c->edge && c->node && c->node->status.reachable && !c->node->status.sptps)
  46                         send_ans_key(c->node);
  47 #endif
  48
  49         /* Force key exchange for connections using SPTPS */
  50
  51         if(experimental) {
  52                 for splay_each(node_t, n, node_tree)
  53                         if(n->status.reachable && n->status.validkey && n->status.sptps)
  54                                 sptps_force_kex(&n->sptps);
  55         }
  56 }
  57
  58 bool key_changed_h(connection_t *c, const char *request) {
  59         char name[MAX_STRING_SIZE];
  60         node_t *n;
  61
  62         if(sscanf(request, "%*d %*x " MAX_STRING, name) != 1) {
  63                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s)", "KEY_CHANGED",
  64                            c->name, c->hostname);
  65                 return false;
  66         }
  67
  68         if(seen_request(request))
  69                 return true;
  70
  71         n = lookup_node(name);
  72
  73         if(!n) {
  74                 logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) origin %s which does not exist",
  75                            "KEY_CHANGED", c->name, c->hostname, name);
  76                 return true;
  77         }
  78
  79         if(!n->status.sptps) {
  80                 n->status.validkey = false;
  81                 n->last_req_key = 0;
  82         }
  83
  84         /* Tell the others */
  85
  86         if(!tunnelserver)
  87                 forward_request(c, request);
  88
  89         return true;
  90 }
  91
  92 static bool send_sptps_data_myself(void *handle, uint8_t type, const void *data, size_t len) {
  93         return send_sptps_data(handle, myself, type, data, len);
  94 }
  95
  96 static bool send_initial_sptps_data(void *handle, uint8_t type, const void *data, size_t len) {
  97         node_t *to = handle;
  98         to->sptps.send_data = send_sptps_data_myself;
  99         char buf[len * 4 / 3 + 5];
 100         b64encode(data, buf, len);
 101         return send_request(to->nexthop->connection, "%d %s %s %d %s", REQ_KEY, myself->name, to->name, REQ_KEY, buf);
 102 }
 103
 104 bool send_req_key(node_t *to) {
 105         if(to->status.sptps) {
 106                 if(!node_read_ecdsa_public_key(to)) {
 107                         logger(DEBUG_PROTOCOL, LOG_DEBUG, "No Ed25519 key known for %s (%s)", to->name, to->hostname);
 108                         send_request(to->nexthop->connection, "%d %s %s %d", REQ_KEY, myself->name, to->name, REQ_PUBKEY);
 109                         return true;
 110                 }
 111
 112                 if(to->sptps.label)
 113                         logger(DEBUG_ALWAYS, LOG_DEBUG, "send_req_key(%s) called while sptps->label != NULL!", to->name);
 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                 sptps_stop(&to->sptps);
 118                 to->status.validkey = false;
 119                 to->status.waitingforkey = true;
 120                 to->last_req_key = now.tv_sec;
 121                 to->incompression = myself->incompression;
 122                 return sptps_start(&to->sptps, to, true, true, myself->connection->ecdsa, to->ecdsa, label, sizeof label, send_initial_sptps_data, receive_sptps_record);
 123         }
 124
 125         return send_request(to->nexthop->connection, "%d %s %s", REQ_KEY, myself->name, to->name);
 126 }
 127
 128 /* REQ_KEY is overloaded to allow arbitrary requests to be routed between two nodes. */
 129
 130 static bool req_key_ext_h(connection_t *c, const char *request, node_t *from, node_t *to, int reqno) {
 131         /* If this is a SPTPS packet, see if sending UDP info helps.
 132            Note that we only do this if we're the destination or the static relay;
 133            otherwise every hop would initiate its own UDP info message, resulting in elevated chatter. */
 134         if((reqno == REQ_KEY || reqno == SPTPS_PACKET) && to->via == myself)
 135                 send_udp_info(myself, from);
 136
 137         if(reqno == SPTPS_PACKET) {
 138                 /* This is a SPTPS data packet. */
 139
 140                 char buf[MAX_STRING_SIZE];
 141                 int len;
 142                 if(sscanf(request, "%*d %*s %*s %*d " MAX_STRING, buf) != 1 || !(len = b64decode(buf, buf, strlen(buf)))) {
 143                         logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s) to %s (%s): %s", "SPTPS_PACKET", from->name, from->hostname, to->name, to->hostname, "invalid SPTPS data");
 144                         return true;
 145                 }
 146
 147                 if(to != myself) {
 148                         /* We don't just forward the request, because we want to use UDP if it's available. */
 149                         send_sptps_data(to, from, 0, buf, len);
 150                         try_tx(to, true);
 151                 } else {
 152                         /* The packet is for us */
 153                         if(!from->status.validkey) {
 154                                 logger(DEBUG_PROTOCOL, LOG_ERR, "Got SPTPS_PACKET from %s (%s) but we don't have a valid key yet", from->name, from->hostname);
 155                                 return true;
 156                         }
 157                         sptps_receive_data(&from->sptps, buf, len);
 158                         send_mtu_info(myself, from, MTU);
 159                 }
 160
 161                 return true;
 162         }
 163
 164         /* Requests that are not SPTPS data packets are forwarded as-is. */
 165
 166         if (to != myself)
 167                 return send_request(to->nexthop->connection, "%s", request);
 168
 169         /* The request is for us */
 170
 171         switch(reqno) {
 172                 case REQ_PUBKEY: {
 173                         if(!node_read_ecdsa_public_key(from)) {
 174                                 /* Request their key *before* we send our key back. Otherwise the first SPTPS packet from them will get dropped. */
 175                                 logger(DEBUG_PROTOCOL, LOG_DEBUG, "Preemptively requesting Ed25519 key for %s (%s)", from->name, from->hostname);
 176                                 send_request(from->nexthop->connection, "%d %s %s %d", REQ_KEY, myself->name, from->name, REQ_PUBKEY);
 177                         }
 178                         char *pubkey = ecdsa_get_base64_public_key(myself->connection->ecdsa);
 179                         send_request(from->nexthop->connection, "%d %s %s %d %s", REQ_KEY, myself->name, from->name, ANS_PUBKEY, pubkey);
 180                         free(pubkey);
 181                         return true;
 182                 }
 183
 184                 case ANS_PUBKEY: {
 185                         if(node_read_ecdsa_public_key(from)) {
 186                                 logger(DEBUG_PROTOCOL, LOG_WARNING, "Got ANS_PUBKEY from %s (%s) even though we already have his pubkey", from->name, from->hostname);
 187                                 return true;
 188                         }
 189
 190                         char pubkey[MAX_STRING_SIZE];
 191                         if(sscanf(request, "%*d %*s %*s %*d " MAX_STRING, pubkey) != 1 || !(from->ecdsa = ecdsa_set_base64_public_key(pubkey))) {
 192                                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "ANS_PUBKEY", from->name, from->hostname, "invalid pubkey");
 193                                 return true;
 194                         }
 195
 196                         logger(DEBUG_PROTOCOL, LOG_INFO, "Learned Ed25519 public key from %s (%s)", from->name, from->hostname);
 197                         append_config_file(from->name, "Ed25519PublicKey", pubkey);
 198                         return true;
 199                 }
 200
 201                 case REQ_KEY: {
 202                         if(!node_read_ecdsa_public_key(from)) {
 203                                 logger(DEBUG_PROTOCOL, LOG_DEBUG, "No Ed25519 key known for %s (%s)", from->name, from->hostname);
 204                                 send_request(from->nexthop->connection, "%d %s %s %d", REQ_KEY, myself->name, from->name, REQ_PUBKEY);
 205                                 return true;
 206                         }
 207
 208                         if(from->sptps.label)
 209                                 logger(DEBUG_ALWAYS, LOG_DEBUG, "Got REQ_KEY from %s while we already started a SPTPS session!", from->name);
 210
 211                         char buf[MAX_STRING_SIZE];
 212                         int len;
 213
 214                         if(sscanf(request, "%*d %*s %*s %*d " MAX_STRING, buf) != 1 || !(len = b64decode(buf, buf, strlen(buf)))) {
 215                                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "REQ_SPTPS_START", from->name, from->hostname, "invalid SPTPS data");
 216                                 return true;
 217                         }
 218
 219                         char label[25 + strlen(from->name) + strlen(myself->name)];
 220                         snprintf(label, sizeof label, "tinc UDP key expansion %s %s", from->name, myself->name);
 221                         sptps_stop(&from->sptps);
 222                         from->status.validkey = false;
 223                         from->status.waitingforkey = true;
 224                         from->last_req_key = now.tv_sec;
 225                         sptps_start(&from->sptps, from, false, true, myself->connection->ecdsa, from->ecdsa, label, sizeof label, send_sptps_data_myself, receive_sptps_record);
 226                         sptps_receive_data(&from->sptps, buf, len);
 227                         send_mtu_info(myself, from, MTU);
 228                         return true;
 229                 }
 230
 231                 default:
 232                         logger(DEBUG_ALWAYS, LOG_ERR, "Unknown extended REQ_KEY request from %s (%s): %s", from->name, from->hostname, request);
 233                         return true;
 234         }
 235 }
 236
 237 bool req_key_h(connection_t *c, const char *request) {
 238         char from_name[MAX_STRING_SIZE];
 239         char to_name[MAX_STRING_SIZE];
 240         node_t *from, *to;
 241         int reqno = 0;
 242
 243         if(sscanf(request, "%*d " MAX_STRING " " MAX_STRING " %d", from_name, to_name, &reqno) < 2) {
 244                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s)", "REQ_KEY", c->name,
 245                            c->hostname);
 246                 return false;
 247         }
 248
 249         if(!check_id(from_name) || !check_id(to_name)) {
 250                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "REQ_KEY", c->name, c->hostname, "invalid name");
 251                 return false;
 252         }
 253
 254         from = lookup_node(from_name);
 255
 256         if(!from) {
 257                 logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) origin %s which does not exist in our connection list",
 258                            "REQ_KEY", c->name, c->hostname, from_name);
 259                 return true;
 260         }
 261
 262         to = lookup_node(to_name);
 263
 264         if(!to) {
 265                 logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) destination %s which does not exist in our connection list",
 266                            "REQ_KEY", c->name, c->hostname, to_name);
 267                 return true;
 268         }
 269
 270         /* Check if this key request is for us */
 271
 272         if(to == myself) {                      /* Yes */
 273                 /* Is this an extended REQ_KEY message? */
 274                 if(experimental && reqno)
 275                         return req_key_ext_h(c, request, from, to, reqno);
 276
 277                 /* No, just send our key back */
 278                 send_ans_key(from);
 279         } else {
 280                 if(tunnelserver)
 281                         return true;
 282
 283                 if(!to->status.reachable) {
 284                         logger(DEBUG_PROTOCOL, LOG_WARNING, "Got %s from %s (%s) destination %s which is not reachable",
 285                                 "REQ_KEY", c->name, c->hostname, to_name);
 286                         return true;
 287                 }
 288
 289                 /* Is this an extended REQ_KEY message? */
 290                 if(experimental && reqno)
 291                         return req_key_ext_h(c, request, from, to, reqno);
 292
 293                 send_request(to->nexthop->connection, "%s", request);
 294         }
 295
 296         return true;
 297 }
 298
 299 bool send_ans_key(node_t *to) {
 300         if(to->status.sptps)
 301                 abort();
 302
 303 #ifdef DISABLE_LEGACY
 304         return false;
 305 #else
 306         size_t keylen = myself->incipher ? cipher_keylength(myself->incipher) : 1;
 307         char key[keylen * 2 + 1];
 308
 309         randomize(key, keylen);
 310
 311         cipher_close(to->incipher);
 312         digest_close(to->indigest);
 313
 314         if(myself->incipher) {
 315                 to->incipher = cipher_open_by_nid(cipher_get_nid(myself->incipher));
 316                 if(!to->incipher)
 317                         abort();
 318                 if(!cipher_set_key(to->incipher, key, false))
 319                         abort();
 320         }
 321
 322         if(myself->indigest) {
 323                 to->indigest = digest_open_by_nid(digest_get_nid(myself->indigest), digest_length(myself->indigest));
 324                 if(!to->indigest)
 325                         abort();
 326                 if(!digest_set_key(to->indigest, key, keylen))
 327                         abort();
 328         }
 329
 330         to->incompression = myself->incompression;
 331
 332         bin2hex(key, key, keylen);
 333
 334         // Reset sequence number and late packet window
 335         mykeyused = true;
 336         to->received_seqno = 0;
 337         to->received = 0;
 338         if(replaywin) memset(to->late, 0, replaywin);
 339
 340         to->status.validkey_in = true;
 341
 342         return send_request(to->nexthop->connection, "%d %s %s %s %d %d %d %d", ANS_KEY,
 343                                                 myself->name, to->name, key,
 344                                                 cipher_get_nid(to->incipher),
 345                                                 digest_get_nid(to->indigest),
 346                                                 (int)digest_length(to->indigest),
 347                                                 to->incompression);
 348 #endif
 349 }
 350
 351 bool ans_key_h(connection_t *c, const char *request) {
 352         char from_name[MAX_STRING_SIZE];
 353         char to_name[MAX_STRING_SIZE];
 354         char key[MAX_STRING_SIZE];
 355         char address[MAX_STRING_SIZE] = "";
 356         char port[MAX_STRING_SIZE] = "";
 357         int cipher, digest, maclength, compression, keylen;
 358         node_t *from, *to;
 359
 360         if(sscanf(request, "%*d "MAX_STRING" "MAX_STRING" "MAX_STRING" %d %d %d %d "MAX_STRING" "MAX_STRING,
 361                 from_name, to_name, key, &cipher, &digest, &maclength,
 362                 &compression, address, port) < 7) {
 363                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s)", "ANS_KEY", c->name,
 364                            c->hostname);
 365                 return false;
 366         }
 367
 368         if(!check_id(from_name) || !check_id(to_name)) {
 369                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "ANS_KEY", c->name, c->hostname, "invalid name");
 370                 return false;
 371         }
 372
 373         from = lookup_node(from_name);
 374
 375         if(!from) {
 376                 logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) origin %s which does not exist in our connection list",
 377                            "ANS_KEY", c->name, c->hostname, from_name);
 378                 return true;
 379         }
 380
 381         to = lookup_node(to_name);
 382
 383         if(!to) {
 384                 logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) destination %s which does not exist in our connection list",
 385                            "ANS_KEY", c->name, c->hostname, to_name);
 386                 return true;
 387         }
 388
 389         /* Forward it if necessary */
 390
 391         if(to != myself) {
 392                 if(tunnelserver)
 393                         return true;
 394
 395                 if(!to->status.reachable) {
 396                         logger(DEBUG_ALWAYS, LOG_WARNING, "Got %s from %s (%s) destination %s which is not reachable",
 397                                    "ANS_KEY", c->name, c->hostname, to_name);
 398                         return true;
 399                 }
 400
 401                 if(!*address && from->address.sa.sa_family != AF_UNSPEC) {
 402                         char *address, *port;
 403                         logger(DEBUG_PROTOCOL, LOG_DEBUG, "Appending reflexive UDP address to ANS_KEY from %s to %s", from->name, to->name);
 404                         sockaddr2str(&from->address, &address, &port);
 405                         send_request(to->nexthop->connection, "%s %s %s", request, address, port);
 406                         free(address);
 407                         free(port);
 408                         return true;
 409                 }
 410
 411                 return send_request(to->nexthop->connection, "%s", request);
 412         }
 413
 414 #ifndef DISABLE_LEGACY
 415         /* Don't use key material until every check has passed. */
 416         cipher_close(from->outcipher);
 417         digest_close(from->outdigest);
 418 #endif
 419         from->status.validkey = false;
 420
 421         if(compression < 0 || compression > 11) {
 422                 logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses bogus compression level!", from->name, from->hostname);
 423                 return true;
 424         }
 425
 426         from->outcompression = compression;
 427
 428         /* SPTPS or old-style key exchange? */
 429
 430         if(from->status.sptps) {
 431                 char buf[strlen(key)];
 432                 int len = b64decode(key, buf, strlen(key));
 433
 434                 if(!len || !sptps_receive_data(&from->sptps, buf, len))
 435                         logger(DEBUG_ALWAYS, LOG_ERR, "Error processing SPTPS data from %s (%s)", from->name, from->hostname);
 436
 437                 if(from->status.validkey) {
 438                         if(*address && *port) {
 439                                 logger(DEBUG_PROTOCOL, LOG_DEBUG, "Using reflexive UDP address from %s: %s port %s", from->name, address, port);
 440                                 sockaddr_t sa = str2sockaddr(address, port);
 441                                 update_node_udp(from, &sa);
 442                         }
 443                 }
 444
 445                 send_mtu_info(myself, from, MTU);
 446
 447                 return true;
 448         }
 449
 450 #ifdef DISABLE_LEGACY
 451         logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses legacy protocol!", from->name, from->hostname);
 452         return false;
 453 #else
 454         /* Check and lookup cipher and digest algorithms */
 455
 456         if(cipher) {
 457                 if(!(from->outcipher = cipher_open_by_nid(cipher))) {
 458                         logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses unknown cipher!", from->name, from->hostname);
 459                         return false;
 460                 }
 461         } else {
 462                 from->outcipher = NULL;
 463         }
 464
 465         if(digest) {
 466                 if(!(from->outdigest = digest_open_by_nid(digest, maclength))) {
 467                         logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses unknown digest!", from->name, from->hostname);
 468                         return false;
 469                 }
 470         } else {
 471                 from->outdigest = NULL;
 472         }
 473
 474         if(maclength != digest_length(from->outdigest)) {
 475                 logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses bogus MAC length!", from->name, from->hostname);
 476                 return false;
 477         }
 478
 479         /* Process key */
 480
 481         keylen = hex2bin(key, key, sizeof key);
 482
 483         if(keylen != (from->outcipher ? cipher_keylength(from->outcipher) : 1)) {
 484                 logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses wrong keylength!", from->name, from->hostname);
 485                 return true;
 486         }
 487
 488         /* Update our copy of the origin's packet key */
 489
 490         if(from->outcipher && !cipher_set_key(from->outcipher, key, true))
 491                 return false;
 492         if(from->outdigest && !digest_set_key(from->outdigest, key, keylen))
 493                 return false;
 494
 495         from->status.validkey = true;
 496         from->sent_seqno = 0;
 497
 498         if(*address && *port) {
 499                 logger(DEBUG_PROTOCOL, LOG_DEBUG, "Using reflexive UDP address from %s: %s port %s", from->name, address, port);
 500                 sockaddr_t sa = str2sockaddr(address, port);
 501                 update_node_udp(from, &sa);
 502         }
 503
 504         return true;
 505 #endif
 506 }