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                   2000-2012 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 ECDSA 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                 char label[25 + strlen(myself->name) + strlen(to->name)];
 106                 snprintf(label, sizeof label, "tinc UDP key expansion %s %s", myself->name, to->name);
 107                 sptps_stop(&to->sptps);
 108                 to->status.validkey = false;
 109                 to->status.waitingforkey = true;
 110                 to->last_req_key = time(NULL);
 111                 to->incompression = myself->incompression;
 112                 return sptps_start(&to->sptps, to, true, true, myself->connection->ecdsa, to->ecdsa, label, sizeof label, send_initial_sptps_data, receive_sptps_record);
 113         }
 114
 115         return send_request(to->nexthop->connection, "%d %s %s", REQ_KEY, myself->name, to->name);
 116 }
 117
 118 /* REQ_KEY is overloaded to allow arbitrary requests to be routed between two nodes. */
 119
 120 static bool req_key_ext_h(connection_t *c, const char *request, node_t *from, int reqno) {
 121         switch(reqno) {
 122                 case REQ_PUBKEY: {
 123                         char *pubkey = ecdsa_get_base64_public_key(&myself->connection->ecdsa);
 124                         send_request(from->nexthop->connection, "%d %s %s %d %s", REQ_KEY, myself->name, from->name, ANS_PUBKEY, pubkey);
 125                         free(pubkey);
 126                         return true;
 127                 }
 128
 129                 case ANS_PUBKEY: {
 130                         if(node_read_ecdsa_public_key(from)) {
 131                                 logger(DEBUG_PROTOCOL, LOG_WARNING, "Got ANS_PUBKEY from %s (%s) even though we already have his pubkey", from->name, from->hostname);
 132                                 return true;
 133                         }
 134
 135                         char pubkey[MAX_STRING_SIZE];
 136                         if(sscanf(request, "%*d %*s %*s %*d " MAX_STRING, pubkey) != 1 || !ecdsa_set_base64_public_key(&from->ecdsa, pubkey)) {
 137                                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "ANS_PUBKEY", from->name, from->hostname, "invalid pubkey");
 138                                 return true;
 139                         }
 140
 141                         logger(DEBUG_PROTOCOL, LOG_INFO, "Learned ECDSA public key from %s (%s)", from->name, from->hostname);
 142                         append_config_file(from->name, "ECDSAPublicKey", pubkey);
 143                         return true;
 144                 }
 145
 146                 case REQ_KEY: {
 147                         if(!node_read_ecdsa_public_key(from)) {
 148                                 logger(DEBUG_PROTOCOL, LOG_DEBUG, "No ECDSA key known for %s (%s)", from->name, from->hostname);
 149                                 send_request(from->nexthop->connection, "%d %s %s %d", REQ_KEY, myself->name, from->name, REQ_PUBKEY);
 150                                 return true;
 151                         }
 152                 }
 153
 154                 case REQ_SPTPS: {
 155                         char buf[MAX_STRING_SIZE];
 156                         if(sscanf(request, "%*d %*s %*s %*d " MAX_STRING, buf) != 1) {
 157                                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "REQ_KEY", from->name, from->hostname, "invalid SPTPS data");
 158                                 return true;
 159                         }
 160                         int len = b64decode(buf, buf, strlen(buf));
 161
 162
 163                         char label[25 + strlen(from->name) + strlen(myself->name)];
 164                         snprintf(label, sizeof label, "tinc UDP key expansion %s %s", from->name, myself->name);
 165                         sptps_stop(&from->sptps);
 166                         from->status.validkey = false;
 167                         from->status.waitingforkey = true;
 168                         from->last_req_key = time(NULL);
 169                         sptps_start(&from->sptps, from, false, true, myself->connection->ecdsa, from->ecdsa, label, sizeof label, send_sptps_data, receive_sptps_record);
 170                         sptps_receive_data(&from->sptps, buf, len);
 171                         return true;
 172                 }
 173
 174                 case REQ_PACKET: {
 175                         if(!from->status.validkey) {
 176                                 logger(DEBUG_PROTOCOL, LOG_ERR, "Got REQ_PACKET from %s (%s) but we don't have a valid key yet", from->name, from->hostname);
 177                                 return true;
 178                         }
 179
 180                         char buf[MAX_STRING_SIZE];
 181                         if(sscanf(request, "%*d %*s %*s %*d " MAX_STRING, buf) != 1) {
 182                                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "REQ_KEY", from->name, from->hostname, "invalid SPTPS data");
 183                                 return true;
 184                         }
 185                         int len = b64decode(buf, buf, strlen(buf));
 186                         sptps_receive_data(&from->sptps, buf, len);
 187                         return true;
 188                 }
 189
 190                 default:
 191                         logger(DEBUG_ALWAYS, LOG_ERR, "Unknown extended REQ_KEY request from %s (%s): %s", from->name, from->hostname, request);
 192                         return true;
 193         }
 194 }
 195
 196 bool req_key_h(connection_t *c, const char *request) {
 197         char from_name[MAX_STRING_SIZE];
 198         char to_name[MAX_STRING_SIZE];
 199         node_t *from, *to;
 200         int reqno = 0;
 201
 202         if(sscanf(request, "%*d " MAX_STRING " " MAX_STRING " %d", from_name, to_name, &reqno) < 2) {
 203                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s)", "REQ_KEY", c->name,
 204                            c->hostname);
 205                 return false;
 206         }
 207
 208         if(!check_id(from_name) || !check_id(to_name)) {
 209                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "REQ_KEY", c->name, c->hostname, "invalid name");
 210                 return false;
 211         }
 212
 213         from = lookup_node(from_name);
 214
 215         if(!from) {
 216                 logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) origin %s which does not exist in our connection list",
 217                            "REQ_KEY", c->name, c->hostname, from_name);
 218                 return true;
 219         }
 220
 221         to = lookup_node(to_name);
 222
 223         if(!to) {
 224                 logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) destination %s which does not exist in our connection list",
 225                            "REQ_KEY", c->name, c->hostname, to_name);
 226                 return true;
 227         }
 228
 229         /* Check if this key request is for us */
 230
 231         if(to == myself) {                      /* Yes */
 232                 /* Is this an extended REQ_KEY message? */
 233                 if(experimental && reqno)
 234                         return req_key_ext_h(c, request, from, reqno);
 235
 236                 /* No, just send our key back */
 237                 send_ans_key(from);
 238         } else {
 239                 if(tunnelserver)
 240                         return true;
 241
 242                 if(!to->status.reachable) {
 243                         logger(DEBUG_PROTOCOL, LOG_WARNING, "Got %s from %s (%s) destination %s which is not reachable",
 244                                 "REQ_KEY", c->name, c->hostname, to_name);
 245                         return true;
 246                 }
 247
 248                 send_request(to->nexthop->connection, "%s", request);
 249         }
 250
 251         return true;
 252 }
 253
 254 bool send_ans_key(node_t *to) {
 255         if(to->status.sptps)
 256                 abort();
 257
 258         size_t keylen = cipher_keylength(&myself->incipher);
 259         char key[keylen * 2 + 1];
 260
 261         cipher_open_by_nid(&to->incipher, cipher_get_nid(&myself->incipher));
 262         digest_open_by_nid(&to->indigest, digest_get_nid(&myself->indigest), digest_length(&myself->indigest));
 263         to->incompression = myself->incompression;
 264
 265         randomize(key, keylen);
 266         cipher_set_key(&to->incipher, key, false);
 267         digest_set_key(&to->indigest, key, keylen);
 268
 269         bin2hex(key, key, keylen);
 270
 271         // Reset sequence number and late packet window
 272         mykeyused = true;
 273         to->received_seqno = 0;
 274         if(replaywin) memset(to->late, 0, replaywin);
 275
 276         return send_request(to->nexthop->connection, "%d %s %s %s %d %d %d %d", ANS_KEY,
 277                                                 myself->name, to->name, key,
 278                                                 cipher_get_nid(&to->incipher),
 279                                                 digest_get_nid(&to->indigest),
 280                                                 (int)digest_length(&to->indigest),
 281                                                 to->incompression);
 282 }
 283
 284 bool ans_key_h(connection_t *c, const char *request) {
 285         char from_name[MAX_STRING_SIZE];
 286         char to_name[MAX_STRING_SIZE];
 287         char key[MAX_STRING_SIZE];
 288         char address[MAX_STRING_SIZE] = "";
 289         char port[MAX_STRING_SIZE] = "";
 290         int cipher, digest, maclength, compression, keylen;
 291         node_t *from, *to;
 292
 293         if(sscanf(request, "%*d "MAX_STRING" "MAX_STRING" "MAX_STRING" %d %d %d %d "MAX_STRING" "MAX_STRING,
 294                 from_name, to_name, key, &cipher, &digest, &maclength,
 295                 &compression, address, port) < 7) {
 296                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s)", "ANS_KEY", c->name,
 297                            c->hostname);
 298                 return false;
 299         }
 300
 301         if(!check_id(from_name) || !check_id(to_name)) {
 302                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "ANS_KEY", c->name, c->hostname, "invalid name");
 303                 return false;
 304         }
 305
 306         from = lookup_node(from_name);
 307
 308         if(!from) {
 309                 logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) origin %s which does not exist in our connection list",
 310                            "ANS_KEY", c->name, c->hostname, from_name);
 311                 return true;
 312         }
 313
 314         to = lookup_node(to_name);
 315
 316         if(!to) {
 317                 logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) destination %s which does not exist in our connection list",
 318                            "ANS_KEY", c->name, c->hostname, to_name);
 319                 return true;
 320         }
 321
 322         /* Forward it if necessary */
 323
 324         if(to != myself) {
 325                 if(tunnelserver)
 326                         return true;
 327
 328                 if(!to->status.reachable) {
 329                         logger(DEBUG_ALWAYS, LOG_WARNING, "Got %s from %s (%s) destination %s which is not reachable",
 330                                    "ANS_KEY", c->name, c->hostname, to_name);
 331                         return true;
 332                 }
 333
 334                 if(!*address && from->address.sa.sa_family != AF_UNSPEC) {
 335                         char *address, *port;
 336                         logger(DEBUG_PROTOCOL, LOG_DEBUG, "Appending reflexive UDP address to ANS_KEY from %s to %s", from->name, to->name);
 337                         sockaddr2str(&from->address, &address, &port);
 338                         send_request(to->nexthop->connection, "%s %s %s", request, address, port);
 339                         free(address);
 340                         free(port);
 341                         return true;
 342                 }
 343
 344                 return send_request(to->nexthop->connection, "%s", request);
 345         }
 346
 347         /* Don't use key material until every check has passed. */
 348         from->status.validkey = false;
 349
 350         if(compression < 0 || compression > 11) {
 351                 logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses bogus compression level!", from->name, from->hostname);
 352                 return true;
 353         }
 354
 355         from->outcompression = compression;
 356
 357         /* SPTPS or old-style key exchange? */
 358
 359         if(from->status.sptps) {
 360                 char buf[strlen(key)];
 361                 int len = b64decode(key, buf, strlen(key));
 362
 363                 if(!sptps_receive_data(&from->sptps, buf, len))
 364                         logger(DEBUG_ALWAYS, LOG_ERR, "Error processing SPTPS data from %s (%s)", from->name, from->hostname);
 365
 366                 if(from->status.validkey) {
 367                         if(*address && *port) {
 368                                 logger(DEBUG_PROTOCOL, LOG_DEBUG, "Using reflexive UDP address from %s: %s port %s", from->name, address, port);
 369                                 sockaddr_t sa = str2sockaddr(address, port);
 370                                 update_node_udp(from, &sa);
 371                         }
 372
 373                         if(from->options & OPTION_PMTU_DISCOVERY)
 374                                 send_mtu_probe(from);
 375                 }
 376
 377                 return true;
 378         }
 379
 380         /* Check and lookup cipher and digest algorithms */
 381
 382         if(!cipher_open_by_nid(&from->outcipher, cipher)) {
 383                 logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses unknown cipher!", from->name, from->hostname);
 384                 return false;
 385         }
 386
 387         if(!digest_open_by_nid(&from->outdigest, digest, maclength)) {
 388                 logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses unknown digest!", from->name, from->hostname);
 389                 return false;
 390         }
 391
 392         if(maclength != digest_length(&from->outdigest)) {
 393                 logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses bogus MAC length!", from->name, from->hostname);
 394                 return false;
 395         }
 396
 397         /* Process key */
 398
 399         keylen = hex2bin(key, key, sizeof key);
 400
 401         if(keylen != cipher_keylength(&from->outcipher)) {
 402                 logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses wrong keylength!", from->name, from->hostname);
 403                 return true;
 404         }
 405
 406         /* Update our copy of the origin's packet key */
 407
 408         cipher_set_key(&from->outcipher, key, true);
 409         digest_set_key(&from->outdigest, key, keylen);
 410
 411         from->status.validkey = true;
 412         from->sent_seqno = 0;
 413
 414         if(*address && *port) {
 415                 logger(DEBUG_PROTOCOL, LOG_DEBUG, "Using reflexive UDP address from %s: %s port %s", from->name, address, port);
 416                 sockaddr_t sa = str2sockaddr(address, port);
 417                 update_node_udp(from, &sa);
 418         }
 419
 420         if(from->options & OPTION_PMTU_DISCOVERY)
 421                 send_mtu_probe(from);
 422
 423         return true;
 424 }