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                   2000-2013 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->status.active && 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 char *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                         char *pubkey = ecdsa_get_base64_public_key(myself->connection->ecdsa);
 128                         send_request(from->nexthop->connection, "%d %s %s %d %s", REQ_KEY, myself->name, from->name, ANS_PUBKEY, pubkey);
 129                         free(pubkey);
 130                         return true;
 131                 }
 132
 133                 case ANS_PUBKEY: {
 134                         if(node_read_ecdsa_public_key(from)) {
 135                                 logger(DEBUG_PROTOCOL, LOG_WARNING, "Got ANS_PUBKEY from %s (%s) even though we already have his pubkey", from->name, from->hostname);
 136                                 return true;
 137                         }
 138
 139                         char pubkey[MAX_STRING_SIZE];
 140                         if(sscanf(request, "%*d %*s %*s %*d " MAX_STRING, pubkey) != 1 || !(from->ecdsa = ecdsa_set_base64_public_key(pubkey))) {
 141                                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "ANS_PUBKEY", from->name, from->hostname, "invalid pubkey");
 142                                 return true;
 143                         }
 144
 145                         logger(DEBUG_PROTOCOL, LOG_INFO, "Learned Ed25519 public key from %s (%s)", from->name, from->hostname);
 146                         append_config_file(from->name, "Ed25519PublicKey", pubkey);
 147                         return true;
 148                 }
 149
 150                 case REQ_KEY: {
 151                         if(!node_read_ecdsa_public_key(from)) {
 152                                 logger(DEBUG_PROTOCOL, LOG_DEBUG, "No Ed25519 key known for %s (%s)", from->name, from->hostname);
 153                                 send_request(from->nexthop->connection, "%d %s %s %d", REQ_KEY, myself->name, from->name, REQ_PUBKEY);
 154                                 return true;
 155                         }
 156
 157                         if(from->sptps.label)
 158                                 logger(DEBUG_ALWAYS, LOG_DEBUG, "Got REQ_KEY from %s while we already started a SPTPS session!", from->name);
 159
 160                         char buf[MAX_STRING_SIZE];
 161                         int len;
 162
 163                         if(sscanf(request, "%*d %*s %*s %*d " MAX_STRING, buf) != 1 || !(len = b64decode(buf, buf, strlen(buf)))) {
 164                                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "REQ_SPTPS_START", from->name, from->hostname, "invalid SPTPS data");
 165                                 return true;
 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_stop(&from->sptps);
 171                         from->status.validkey = false;
 172                         from->status.waitingforkey = true;
 173                         from->last_req_key = now.tv_sec;
 174                         sptps_start(&from->sptps, from, false, true, myself->connection->ecdsa, from->ecdsa, label, sizeof label, send_sptps_data, receive_sptps_record);
 175                         sptps_receive_data(&from->sptps, buf, len);
 176                         return true;
 177                 }
 178
 179                 case REQ_SPTPS: {
 180                         if(!from->status.validkey) {
 181                                 logger(DEBUG_PROTOCOL, LOG_ERR, "Got REQ_SPTPS from %s (%s) but we don't have a valid key yet", from->name, from->hostname);
 182                                 return true;
 183                         }
 184
 185                         char buf[MAX_STRING_SIZE];
 186                         int len;
 187                         if(sscanf(request, "%*d %*s %*s %*d " MAX_STRING, buf) != 1 || !(len = b64decode(buf, buf, strlen(buf)))) {
 188                                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "REQ_SPTPS", from->name, from->hostname, "invalid SPTPS data");
 189                                 return true;
 190                         }
 191                         sptps_receive_data(&from->sptps, buf, len);
 192                         return true;
 193                 }
 194
 195                 default:
 196                         logger(DEBUG_ALWAYS, LOG_ERR, "Unknown extended REQ_KEY request from %s (%s): %s", from->name, from->hostname, request);
 197                         return true;
 198         }
 199 }
 200
 201 bool req_key_h(connection_t *c, const char *request) {
 202         char from_name[MAX_STRING_SIZE];
 203         char to_name[MAX_STRING_SIZE];
 204         node_t *from, *to;
 205         int reqno = 0;
 206
 207         if(sscanf(request, "%*d " MAX_STRING " " MAX_STRING " %d", from_name, to_name, &reqno) < 2) {
 208                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s)", "REQ_KEY", c->name,
 209                            c->hostname);
 210                 return false;
 211         }
 212
 213         if(!check_id(from_name) || !check_id(to_name)) {
 214                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "REQ_KEY", c->name, c->hostname, "invalid name");
 215                 return false;
 216         }
 217
 218         from = lookup_node(from_name);
 219
 220         if(!from) {
 221                 logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) origin %s which does not exist in our connection list",
 222                            "REQ_KEY", c->name, c->hostname, from_name);
 223                 return true;
 224         }
 225
 226         to = lookup_node(to_name);
 227
 228         if(!to) {
 229                 logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) destination %s which does not exist in our connection list",
 230                            "REQ_KEY", c->name, c->hostname, to_name);
 231                 return true;
 232         }
 233
 234         /* Check if this key request is for us */
 235
 236         if(to == myself) {                      /* Yes */
 237                 /* Is this an extended REQ_KEY message? */
 238                 if(experimental && reqno)
 239                         return req_key_ext_h(c, request, from, reqno);
 240
 241                 /* No, just send our key back */
 242                 send_ans_key(from);
 243         } else {
 244                 if(tunnelserver)
 245                         return true;
 246
 247                 if(!to->status.reachable) {
 248                         logger(DEBUG_PROTOCOL, LOG_WARNING, "Got %s from %s (%s) destination %s which is not reachable",
 249                                 "REQ_KEY", c->name, c->hostname, to_name);
 250                         return true;
 251                 }
 252
 253                 send_request(to->nexthop->connection, "%s", request);
 254         }
 255
 256         return true;
 257 }
 258
 259 bool send_ans_key(node_t *to) {
 260         if(to->status.sptps)
 261                 abort();
 262
 263         size_t keylen = myself->incipher ? cipher_keylength(myself->incipher) : 1;
 264         char key[keylen * 2 + 1];
 265
 266         randomize(key, keylen);
 267
 268         cipher_close(to->incipher);
 269         digest_close(to->indigest);
 270
 271         if(myself->incipher) {
 272                 to->incipher = cipher_open_by_nid(cipher_get_nid(myself->incipher));
 273                 if(!to->incipher)
 274                         abort();
 275                 if(!cipher_set_key(to->incipher, key, false))
 276                         abort();
 277         }
 278
 279         if(myself->indigest) {
 280                 to->indigest = digest_open_by_nid(digest_get_nid(myself->indigest), digest_length(myself->indigest));
 281                 if(!to->indigest)
 282                         abort();
 283                 if(!digest_set_key(to->indigest, key, keylen))
 284                         abort();
 285         }
 286
 287         to->incompression = myself->incompression;
 288
 289         bin2hex(key, key, keylen);
 290
 291         // Reset sequence number and late packet window
 292         mykeyused = true;
 293         to->received_seqno = 0;
 294         to->received = 0;
 295         if(replaywin) memset(to->late, 0, replaywin);
 296
 297         return send_request(to->nexthop->connection, "%d %s %s %s %d %d %d %d", ANS_KEY,
 298                                                 myself->name, to->name, key,
 299                                                 cipher_get_nid(to->incipher),
 300                                                 digest_get_nid(to->indigest),
 301                                                 (int)digest_length(to->indigest),
 302                                                 to->incompression);
 303 }
 304
 305 bool ans_key_h(connection_t *c, const char *request) {
 306         char from_name[MAX_STRING_SIZE];
 307         char to_name[MAX_STRING_SIZE];
 308         char key[MAX_STRING_SIZE];
 309         char address[MAX_STRING_SIZE] = "";
 310         char port[MAX_STRING_SIZE] = "";
 311         int cipher, digest, maclength, compression, keylen;
 312         node_t *from, *to;
 313
 314         if(sscanf(request, "%*d "MAX_STRING" "MAX_STRING" "MAX_STRING" %d %d %d %d "MAX_STRING" "MAX_STRING,
 315                 from_name, to_name, key, &cipher, &digest, &maclength,
 316                 &compression, address, port) < 7) {
 317                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s)", "ANS_KEY", c->name,
 318                            c->hostname);
 319                 return false;
 320         }
 321
 322         if(!check_id(from_name) || !check_id(to_name)) {
 323                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "ANS_KEY", c->name, c->hostname, "invalid name");
 324                 return false;
 325         }
 326
 327         from = lookup_node(from_name);
 328
 329         if(!from) {
 330                 logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) origin %s which does not exist in our connection list",
 331                            "ANS_KEY", c->name, c->hostname, from_name);
 332                 return true;
 333         }
 334
 335         to = lookup_node(to_name);
 336
 337         if(!to) {
 338                 logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) destination %s which does not exist in our connection list",
 339                            "ANS_KEY", c->name, c->hostname, to_name);
 340                 return true;
 341         }
 342
 343         /* Forward it if necessary */
 344
 345         if(to != myself) {
 346                 if(tunnelserver)
 347                         return true;
 348
 349                 if(!to->status.reachable) {
 350                         logger(DEBUG_ALWAYS, LOG_WARNING, "Got %s from %s (%s) destination %s which is not reachable",
 351                                    "ANS_KEY", c->name, c->hostname, to_name);
 352                         return true;
 353                 }
 354
 355                 if(!*address && from->address.sa.sa_family != AF_UNSPEC) {
 356                         char *address, *port;
 357                         logger(DEBUG_PROTOCOL, LOG_DEBUG, "Appending reflexive UDP address to ANS_KEY from %s to %s", from->name, to->name);
 358                         sockaddr2str(&from->address, &address, &port);
 359                         send_request(to->nexthop->connection, "%s %s %s", request, address, port);
 360                         free(address);
 361                         free(port);
 362                         return true;
 363                 }
 364
 365                 return send_request(to->nexthop->connection, "%s", request);
 366         }
 367
 368         /* Don't use key material until every check has passed. */
 369         cipher_close(from->outcipher);
 370         digest_close(from->outdigest);
 371         from->status.validkey = false;
 372
 373         if(compression < 0 || compression > 11) {
 374                 logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses bogus compression level!", from->name, from->hostname);
 375                 return true;
 376         }
 377
 378         from->outcompression = compression;
 379
 380         /* SPTPS or old-style key exchange? */
 381
 382         if(from->status.sptps) {
 383                 char buf[strlen(key)];
 384                 int len = b64decode(key, buf, strlen(key));
 385
 386                 if(!len || !sptps_receive_data(&from->sptps, buf, len))
 387                         logger(DEBUG_ALWAYS, LOG_ERR, "Error processing SPTPS data from %s (%s)", from->name, from->hostname);
 388
 389                 if(from->status.validkey) {
 390                         if(*address && *port) {
 391                                 logger(DEBUG_PROTOCOL, LOG_DEBUG, "Using reflexive UDP address from %s: %s port %s", from->name, address, port);
 392                                 sockaddr_t sa = str2sockaddr(address, port);
 393                                 update_node_udp(from, &sa);
 394                         }
 395
 396                         if(from->options & OPTION_PMTU_DISCOVERY && !(from->options & OPTION_TCPONLY))
 397                                 send_mtu_probe(from);
 398                 }
 399
 400                 return true;
 401         }
 402
 403         /* Check and lookup cipher and digest algorithms */
 404
 405         if(cipher) {
 406                 if(!(from->outcipher = cipher_open_by_nid(cipher))) {
 407                         logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses unknown cipher!", from->name, from->hostname);
 408                         return false;
 409                 }
 410         } else {
 411                 from->outcipher = NULL;
 412         }
 413
 414         if(digest) {
 415                 if(!(from->outdigest = digest_open_by_nid(digest, maclength))) {
 416                         logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses unknown digest!", from->name, from->hostname);
 417                         return false;
 418                 }
 419         } else {
 420                 from->outdigest = NULL;
 421         }
 422
 423         if(maclength != digest_length(from->outdigest)) {
 424                 logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses bogus MAC length!", from->name, from->hostname);
 425                 return false;
 426         }
 427
 428         /* Process key */
 429
 430         keylen = hex2bin(key, key, sizeof key);
 431
 432         if(keylen != (from->outcipher ? cipher_keylength(from->outcipher) : 1)) {
 433                 logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses wrong keylength!", from->name, from->hostname);
 434                 return true;
 435         }
 436
 437         /* Update our copy of the origin's packet key */
 438
 439         if(from->outcipher && !cipher_set_key(from->outcipher, key, true))
 440                 return false;
 441         if(from->outdigest && !digest_set_key(from->outdigest, key, keylen))
 442                 return false;
 443
 444         from->status.validkey = true;
 445         from->sent_seqno = 0;
 446
 447         if(*address && *port) {
 448                 logger(DEBUG_PROTOCOL, LOG_DEBUG, "Using reflexive UDP address from %s: %s port %s", from->name, address, port);
 449                 sockaddr_t sa = str2sockaddr(address, port);
 450                 update_node_udp(from, &sa);
 451         }
 452
 453         if(from->options & OPTION_PMTU_DISCOVERY && !(from->options & OPTION_TCPONLY))
 454                 send_mtu_probe(from);
 455
 456         return true;
 457 }