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, int reqno) {
 129         switch(reqno) {
 130                 case REQ_PUBKEY: {
 131                         if(!node_read_ecdsa_public_key(from)) {
 132                                 /* Request their key *before* we send our key back. Otherwise the first SPTPS packet from them will get dropped. */
 133                                 logger(DEBUG_PROTOCOL, LOG_DEBUG, "Preemptively requesting Ed25519 key for %s (%s)", from->name, from->hostname);
 134                                 send_request(from->nexthop->connection, "%d %s %s %d", REQ_KEY, myself->name, from->name, REQ_PUBKEY);
 135                         }
 136                         char *pubkey = ecdsa_get_base64_public_key(myself->connection->ecdsa);
 137                         send_request(from->nexthop->connection, "%d %s %s %d %s", REQ_KEY, myself->name, from->name, ANS_PUBKEY, pubkey);
 138                         free(pubkey);
 139                         return true;
 140                 }
 141
 142                 case ANS_PUBKEY: {
 143                         if(node_read_ecdsa_public_key(from)) {
 144                                 logger(DEBUG_PROTOCOL, LOG_WARNING, "Got ANS_PUBKEY from %s (%s) even though we already have his pubkey", from->name, from->hostname);
 145                                 return true;
 146                         }
 147
 148                         char pubkey[MAX_STRING_SIZE];
 149                         if(sscanf(request, "%*d %*s %*s %*d " MAX_STRING, pubkey) != 1 || !(from->ecdsa = ecdsa_set_base64_public_key(pubkey))) {
 150                                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "ANS_PUBKEY", from->name, from->hostname, "invalid pubkey");
 151                                 return true;
 152                         }
 153
 154                         logger(DEBUG_PROTOCOL, LOG_INFO, "Learned Ed25519 public key from %s (%s)", from->name, from->hostname);
 155                         append_config_file(from->name, "Ed25519PublicKey", pubkey);
 156                         return true;
 157                 }
 158
 159                 case REQ_KEY: {
 160                         if(!node_read_ecdsa_public_key(from)) {
 161                                 logger(DEBUG_PROTOCOL, LOG_DEBUG, "No Ed25519 key known for %s (%s)", from->name, from->hostname);
 162                                 send_request(from->nexthop->connection, "%d %s %s %d", REQ_KEY, myself->name, from->name, REQ_PUBKEY);
 163                                 return true;
 164                         }
 165
 166                         if(from->sptps.label)
 167                                 logger(DEBUG_ALWAYS, LOG_DEBUG, "Got REQ_KEY from %s while we already started a SPTPS session!", from->name);
 168
 169                         char buf[MAX_STRING_SIZE];
 170                         int len;
 171
 172                         if(sscanf(request, "%*d %*s %*s %*d " MAX_STRING, buf) != 1 || !(len = b64decode(buf, buf, strlen(buf)))) {
 173                                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "REQ_SPTPS_START", from->name, from->hostname, "invalid SPTPS data");
 174                                 return true;
 175                         }
 176
 177                         char label[25 + strlen(from->name) + strlen(myself->name)];
 178                         snprintf(label, sizeof label, "tinc UDP key expansion %s %s", from->name, myself->name);
 179                         sptps_stop(&from->sptps);
 180                         from->status.validkey = false;
 181                         from->status.waitingforkey = true;
 182                         from->last_req_key = now.tv_sec;
 183                         sptps_start(&from->sptps, from, false, true, myself->connection->ecdsa, from->ecdsa, label, sizeof label, send_sptps_data_myself, receive_sptps_record);
 184                         sptps_receive_data(&from->sptps, buf, len);
 185                         send_mtu_info(myself, from, MTU);
 186                         return true;
 187                 }
 188
 189                 case REQ_SPTPS: {
 190                         if(!from->status.validkey) {
 191                                 logger(DEBUG_PROTOCOL, LOG_ERR, "Got REQ_SPTPS from %s (%s) but we don't have a valid key yet", from->name, from->hostname);
 192                                 return true;
 193                         }
 194
 195                         char buf[MAX_STRING_SIZE];
 196                         int len;
 197                         if(sscanf(request, "%*d %*s %*s %*d " MAX_STRING, buf) != 1 || !(len = b64decode(buf, buf, strlen(buf)))) {
 198                                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "REQ_SPTPS", from->name, from->hostname, "invalid SPTPS data");
 199                                 return true;
 200                         }
 201                         sptps_receive_data(&from->sptps, buf, len);
 202                         send_mtu_info(myself, from, MTU);
 203                         return true;
 204                 }
 205
 206                 default:
 207                         logger(DEBUG_ALWAYS, LOG_ERR, "Unknown extended REQ_KEY request from %s (%s): %s", from->name, from->hostname, request);
 208                         return true;
 209         }
 210 }
 211
 212 bool req_key_h(connection_t *c, const char *request) {
 213         char from_name[MAX_STRING_SIZE];
 214         char to_name[MAX_STRING_SIZE];
 215         node_t *from, *to;
 216         int reqno = 0;
 217
 218         if(sscanf(request, "%*d " MAX_STRING " " MAX_STRING " %d", from_name, to_name, &reqno) < 2) {
 219                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s)", "REQ_KEY", c->name,
 220                            c->hostname);
 221                 return false;
 222         }
 223
 224         if(!check_id(from_name) || !check_id(to_name)) {
 225                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "REQ_KEY", c->name, c->hostname, "invalid name");
 226                 return false;
 227         }
 228
 229         from = lookup_node(from_name);
 230
 231         if(!from) {
 232                 logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) origin %s which does not exist in our connection list",
 233                            "REQ_KEY", c->name, c->hostname, from_name);
 234                 return true;
 235         }
 236
 237         to = lookup_node(to_name);
 238
 239         if(!to) {
 240                 logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) destination %s which does not exist in our connection list",
 241                            "REQ_KEY", c->name, c->hostname, to_name);
 242                 return true;
 243         }
 244
 245         /* If this is a SPTPS packet, see if sending UDP info helps.
 246            Note that we only do this if we're the destination or the static relay;
 247            otherwise every hop would initiate its own UDP info message, resulting in elevated chatter. */
 248
 249         if(experimental && (reqno == REQ_KEY || reqno == REQ_SPTPS) && to->via == myself)
 250                 send_udp_info(myself, from);
 251
 252         /* Check if this key request is for us */
 253
 254         if(to == myself) {                      /* Yes */
 255                 /* Is this an extended REQ_KEY message? */
 256                 if(experimental && reqno)
 257                         return req_key_ext_h(c, request, from, reqno);
 258
 259                 /* No, just send our key back */
 260                 send_ans_key(from);
 261         } else {
 262                 if(tunnelserver)
 263                         return true;
 264
 265                 if(!to->status.reachable) {
 266                         logger(DEBUG_PROTOCOL, LOG_WARNING, "Got %s from %s (%s) destination %s which is not reachable",
 267                                 "REQ_KEY", c->name, c->hostname, to_name);
 268                         return true;
 269                 }
 270
 271                 /* TODO: forwarding SPTPS packets in this way is inefficient because we send them over TCP without checking for UDP connectivity */
 272                 send_request(to->nexthop->connection, "%s", request);
 273         }
 274
 275         return true;
 276 }
 277
 278 bool send_ans_key(node_t *to) {
 279         if(to->status.sptps)
 280                 abort();
 281
 282 #ifdef DISABLE_LEGACY
 283         return false;
 284 #else
 285         size_t keylen = myself->incipher ? cipher_keylength(myself->incipher) : 1;
 286         char key[keylen * 2 + 1];
 287
 288         randomize(key, keylen);
 289
 290         cipher_close(to->incipher);
 291         digest_close(to->indigest);
 292
 293         if(myself->incipher) {
 294                 to->incipher = cipher_open_by_nid(cipher_get_nid(myself->incipher));
 295                 if(!to->incipher)
 296                         abort();
 297                 if(!cipher_set_key(to->incipher, key, false))
 298                         abort();
 299         }
 300
 301         if(myself->indigest) {
 302                 to->indigest = digest_open_by_nid(digest_get_nid(myself->indigest), digest_length(myself->indigest));
 303                 if(!to->indigest)
 304                         abort();
 305                 if(!digest_set_key(to->indigest, key, keylen))
 306                         abort();
 307         }
 308
 309         to->incompression = myself->incompression;
 310
 311         bin2hex(key, key, keylen);
 312
 313         // Reset sequence number and late packet window
 314         mykeyused = true;
 315         to->received_seqno = 0;
 316         to->received = 0;
 317         if(replaywin) memset(to->late, 0, replaywin);
 318
 319         to->status.validkey_in = true;
 320
 321         return send_request(to->nexthop->connection, "%d %s %s %s %d %d %d %d", ANS_KEY,
 322                                                 myself->name, to->name, key,
 323                                                 cipher_get_nid(to->incipher),
 324                                                 digest_get_nid(to->indigest),
 325                                                 (int)digest_length(to->indigest),
 326                                                 to->incompression);
 327 #endif
 328 }
 329
 330 bool ans_key_h(connection_t *c, const char *request) {
 331         char from_name[MAX_STRING_SIZE];
 332         char to_name[MAX_STRING_SIZE];
 333         char key[MAX_STRING_SIZE];
 334         char address[MAX_STRING_SIZE] = "";
 335         char port[MAX_STRING_SIZE] = "";
 336         int cipher, digest, maclength, compression, keylen;
 337         node_t *from, *to;
 338
 339         if(sscanf(request, "%*d "MAX_STRING" "MAX_STRING" "MAX_STRING" %d %d %d %d "MAX_STRING" "MAX_STRING,
 340                 from_name, to_name, key, &cipher, &digest, &maclength,
 341                 &compression, address, port) < 7) {
 342                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s)", "ANS_KEY", c->name,
 343                            c->hostname);
 344                 return false;
 345         }
 346
 347         if(!check_id(from_name) || !check_id(to_name)) {
 348                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "ANS_KEY", c->name, c->hostname, "invalid name");
 349                 return false;
 350         }
 351
 352         from = lookup_node(from_name);
 353
 354         if(!from) {
 355                 logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) origin %s which does not exist in our connection list",
 356                            "ANS_KEY", c->name, c->hostname, from_name);
 357                 return true;
 358         }
 359
 360         to = lookup_node(to_name);
 361
 362         if(!to) {
 363                 logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) destination %s which does not exist in our connection list",
 364                            "ANS_KEY", c->name, c->hostname, to_name);
 365                 return true;
 366         }
 367
 368         /* Forward it if necessary */
 369
 370         if(to != myself) {
 371                 if(tunnelserver)
 372                         return true;
 373
 374                 if(!to->status.reachable) {
 375                         logger(DEBUG_ALWAYS, LOG_WARNING, "Got %s from %s (%s) destination %s which is not reachable",
 376                                    "ANS_KEY", c->name, c->hostname, to_name);
 377                         return true;
 378                 }
 379
 380                 if(!*address && from->address.sa.sa_family != AF_UNSPEC) {
 381                         char *address, *port;
 382                         logger(DEBUG_PROTOCOL, LOG_DEBUG, "Appending reflexive UDP address to ANS_KEY from %s to %s", from->name, to->name);
 383                         sockaddr2str(&from->address, &address, &port);
 384                         send_request(to->nexthop->connection, "%s %s %s", request, address, port);
 385                         free(address);
 386                         free(port);
 387                         return true;
 388                 }
 389
 390                 return send_request(to->nexthop->connection, "%s", request);
 391         }
 392
 393 #ifndef DISABLE_LEGACY
 394         /* Don't use key material until every check has passed. */
 395         cipher_close(from->outcipher);
 396         digest_close(from->outdigest);
 397 #endif
 398         from->status.validkey = false;
 399
 400         if(compression < 0 || compression > 11) {
 401                 logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses bogus compression level!", from->name, from->hostname);
 402                 return true;
 403         }
 404
 405         from->outcompression = compression;
 406
 407         /* SPTPS or old-style key exchange? */
 408
 409         if(from->status.sptps) {
 410                 char buf[strlen(key)];
 411                 int len = b64decode(key, buf, strlen(key));
 412
 413                 if(!len || !sptps_receive_data(&from->sptps, buf, len))
 414                         logger(DEBUG_ALWAYS, LOG_ERR, "Error processing SPTPS data from %s (%s)", from->name, from->hostname);
 415
 416                 if(from->status.validkey) {
 417                         if(*address && *port) {
 418                                 logger(DEBUG_PROTOCOL, LOG_DEBUG, "Using reflexive UDP address from %s: %s port %s", from->name, address, port);
 419                                 sockaddr_t sa = str2sockaddr(address, port);
 420                                 update_node_udp(from, &sa);
 421                         }
 422                 }
 423
 424                 send_mtu_info(myself, from, MTU);
 425
 426                 return true;
 427         }
 428
 429 #ifdef DISABLE_LEGACY
 430         logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses legacy protocol!", from->name, from->hostname);
 431         return false;
 432 #else
 433         /* Check and lookup cipher and digest algorithms */
 434
 435         if(cipher) {
 436                 if(!(from->outcipher = cipher_open_by_nid(cipher))) {
 437                         logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses unknown cipher!", from->name, from->hostname);
 438                         return false;
 439                 }
 440         } else {
 441                 from->outcipher = NULL;
 442         }
 443
 444         if(digest) {
 445                 if(!(from->outdigest = digest_open_by_nid(digest, maclength))) {
 446                         logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses unknown digest!", from->name, from->hostname);
 447                         return false;
 448                 }
 449         } else {
 450                 from->outdigest = NULL;
 451         }
 452
 453         if(maclength != digest_length(from->outdigest)) {
 454                 logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses bogus MAC length!", from->name, from->hostname);
 455                 return false;
 456         }
 457
 458         /* Process key */
 459
 460         keylen = hex2bin(key, key, sizeof key);
 461
 462         if(keylen != (from->outcipher ? cipher_keylength(from->outcipher) : 1)) {
 463                 logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses wrong keylength!", from->name, from->hostname);
 464                 return true;
 465         }
 466
 467         /* Update our copy of the origin's packet key */
 468
 469         if(from->outcipher && !cipher_set_key(from->outcipher, key, true))
 470                 return false;
 471         if(from->outdigest && !digest_set_key(from->outdigest, key, keylen))
 472                 return false;
 473
 474         from->status.validkey = true;
 475         from->sent_seqno = 0;
 476
 477         if(*address && *port) {
 478                 logger(DEBUG_PROTOCOL, LOG_DEBUG, "Using reflexive UDP address from %s: %s port %s", from->name, address, port);
 479                 sockaddr_t sa = str2sockaddr(address, port);
 480                 update_node_udp(from, &sa);
 481         }
 482
 483         return true;
 484 #endif
 485 }