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