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