www.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 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
 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 = time(NULL);
 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 || !ecdsa_set_base64_public_key(&from->ecdsa, 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 ECDSA public key from %s (%s)", from->name, from->hostname);
 146                         append_config_file(from->name, "ECDSAPublicKey", 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 ECDSA 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                         if(sscanf(request, "%*d %*s %*s %*d " MAX_STRING, buf) != 1) {
 162                                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "REQ_SPTPS_START", from->name, from->hostname, "invalid SPTPS data");
 163                                 return true;
 164                         }
 165                         int len = b64decode(buf, buf, strlen(buf));
 166
 167                         char label[25 + strlen(from->name) + strlen(myself->name)];
 168                         snprintf(label, sizeof label, "tinc UDP key expansion %s %s", from->name, myself->name);
 169                         sptps_stop(&from->sptps);
 170                         from->status.validkey = false;
 171                         from->status.waitingforkey = true;
 172                         from->last_req_key = time(NULL);
 173                         sptps_start(&from->sptps, from, false, true, myself->connection->ecdsa, from->ecdsa, label, sizeof label, send_sptps_data, receive_sptps_record);
 174                         sptps_receive_data(&from->sptps, buf, len);
 175                         return true;
 176                 }
 177
 178                 case REQ_SPTPS: {
 179                         if(!from->status.validkey) {
 180                                 logger(DEBUG_PROTOCOL, LOG_ERR, "Got REQ_SPTPS from %s (%s) but we don't have a valid key yet", from->name, from->hostname);
 181                                 return true;
 182                         }
 183
 184                         char buf[MAX_STRING_SIZE];
 185                         if(sscanf(request, "%*d %*s %*s %*d " MAX_STRING, buf) != 1) {
 186                                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "REQ_SPTPS", from->name, from->hostname, "invalid SPTPS data");
 187                                 return true;
 188                         }
 189                         int len = b64decode(buf, buf, strlen(buf));
 190                         sptps_receive_data(&from->sptps, buf, len);
 191                         return true;
 192                 }
 193
 194                 default:
 195                         logger(DEBUG_ALWAYS, LOG_ERR, "Unknown extended REQ_KEY request from %s (%s): %s", from->name, from->hostname, request);
 196                         return true;
 197         }
 198 }
 199
 200 bool req_key_h(connection_t *c, const char *request) {
 201         char from_name[MAX_STRING_SIZE];
 202         char to_name[MAX_STRING_SIZE];
 203         node_t *from, *to;
 204         int reqno = 0;
 205
 206         if(sscanf(request, "%*d " MAX_STRING " " MAX_STRING " %d", from_name, to_name, &reqno) < 2) {
 207                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s)", "REQ_KEY", c->name,
 208                            c->hostname);
 209                 return false;
 210         }
 211
 212         if(!check_id(from_name) || !check_id(to_name)) {
 213                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "REQ_KEY", c->name, c->hostname, "invalid name");
 214                 return false;
 215         }
 216
 217         from = lookup_node(from_name);
 218
 219         if(!from) {
 220                 logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) origin %s which does not exist in our connection list",
 221                            "REQ_KEY", c->name, c->hostname, from_name);
 222                 return true;
 223         }
 224
 225         to = lookup_node(to_name);
 226
 227         if(!to) {
 228                 logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) destination %s which does not exist in our connection list",
 229                            "REQ_KEY", c->name, c->hostname, to_name);
 230                 return true;
 231         }
 232
 233         /* Check if this key request is for us */
 234
 235         if(to == myself) {                      /* Yes */
 236                 /* Is this an extended REQ_KEY message? */
 237                 if(experimental && reqno)
 238                         return req_key_ext_h(c, request, from, reqno);
 239
 240                 /* No, just send our key back */
 241                 send_ans_key(from);
 242         } else {
 243                 if(tunnelserver)
 244                         return true;
 245
 246                 if(!to->status.reachable) {
 247                         logger(DEBUG_PROTOCOL, LOG_WARNING, "Got %s from %s (%s) destination %s which is not reachable",
 248                                 "REQ_KEY", c->name, c->hostname, to_name);
 249                         return true;
 250                 }
 251
 252                 send_request(to->nexthop->connection, "%s", request);
 253         }
 254
 255         return true;
 256 }
 257
 258 bool send_ans_key(node_t *to) {
 259         if(to->status.sptps)
 260                 abort();
 261
 262         size_t keylen = cipher_keylength(&myself->incipher);
 263         char key[keylen * 2 + 1];
 264
 265         cipher_close(&to->incipher);
 266         digest_close(&to->indigest);
 267
 268         cipher_open_by_nid(&to->incipher, cipher_get_nid(&myself->incipher));
 269         digest_open_by_nid(&to->indigest, digest_get_nid(&myself->indigest), digest_length(&myself->indigest));
 270         to->incompression = myself->incompression;
 271
 272         randomize(key, keylen);
 273         cipher_set_key(&to->incipher, key, false);
 274         digest_set_key(&to->indigest, key, keylen);
 275
 276         bin2hex(key, key, keylen);
 277
 278         // Reset sequence number and late packet window
 279         mykeyused = true;
 280         to->received_seqno = 0;
 281         to->received = 0;
 282         if(replaywin) memset(to->late, 0, replaywin);
 283
 284         return send_request(to->nexthop->connection, "%d %s %s %s %d %d %d %d", ANS_KEY,
 285                                                 myself->name, to->name, key,
 286                                                 cipher_get_nid(&to->incipher),
 287                                                 digest_get_nid(&to->indigest),
 288                                                 (int)digest_length(&to->indigest),
 289                                                 to->incompression);
 290 }
 291
 292 bool ans_key_h(connection_t *c, const char *request) {
 293         char from_name[MAX_STRING_SIZE];
 294         char to_name[MAX_STRING_SIZE];
 295         char key[MAX_STRING_SIZE];
 296         char address[MAX_STRING_SIZE] = "";
 297         char port[MAX_STRING_SIZE] = "";
 298         int cipher, digest, maclength, compression, keylen;
 299         node_t *from, *to;
 300
 301         if(sscanf(request, "%*d "MAX_STRING" "MAX_STRING" "MAX_STRING" %d %d %d %d "MAX_STRING" "MAX_STRING,
 302                 from_name, to_name, key, &cipher, &digest, &maclength,
 303                 &compression, address, port) < 7) {
 304                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s)", "ANS_KEY", c->name,
 305                            c->hostname);
 306                 return false;
 307         }
 308
 309         if(!check_id(from_name) || !check_id(to_name)) {
 310                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "ANS_KEY", c->name, c->hostname, "invalid name");
 311                 return false;
 312         }
 313
 314         from = lookup_node(from_name);
 315
 316         if(!from) {
 317                 logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) origin %s which does not exist in our connection list",
 318                            "ANS_KEY", c->name, c->hostname, from_name);
 319                 return true;
 320         }
 321
 322         to = lookup_node(to_name);
 323
 324         if(!to) {
 325                 logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) destination %s which does not exist in our connection list",
 326                            "ANS_KEY", c->name, c->hostname, to_name);
 327                 return true;
 328         }
 329
 330         /* Forward it if necessary */
 331
 332         if(to != myself) {
 333                 if(tunnelserver)
 334                         return true;
 335
 336                 if(!to->status.reachable) {
 337                         logger(DEBUG_ALWAYS, LOG_WARNING, "Got %s from %s (%s) destination %s which is not reachable",
 338                                    "ANS_KEY", c->name, c->hostname, to_name);
 339                         return true;
 340                 }
 341
 342                 if(!*address && from->address.sa.sa_family != AF_UNSPEC) {
 343                         char *address, *port;
 344                         logger(DEBUG_PROTOCOL, LOG_DEBUG, "Appending reflexive UDP address to ANS_KEY from %s to %s", from->name, to->name);
 345                         sockaddr2str(&from->address, &address, &port);
 346                         send_request(to->nexthop->connection, "%s %s %s", request, address, port);
 347                         free(address);
 348                         free(port);
 349                         return true;
 350                 }
 351
 352                 return send_request(to->nexthop->connection, "%s", request);
 353         }
 354
 355         /* Don't use key material until every check has passed. */
 356         cipher_close(&from->outcipher);
 357         digest_close(&from->outdigest);
 358         from->status.validkey = false;
 359
 360         if(compression < 0 || compression > 11) {
 361                 logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses bogus compression level!", from->name, from->hostname);
 362                 return true;
 363         }
 364
 365         from->outcompression = compression;
 366
 367         /* SPTPS or old-style key exchange? */
 368
 369         if(from->status.sptps) {
 370                 char buf[strlen(key)];
 371                 int len = b64decode(key, buf, strlen(key));
 372
 373                 if(!sptps_receive_data(&from->sptps, buf, len))
 374                         logger(DEBUG_ALWAYS, LOG_ERR, "Error processing SPTPS data from %s (%s)", from->name, from->hostname);
 375
 376                 if(from->status.validkey) {
 377                         if(*address && *port) {
 378                                 logger(DEBUG_PROTOCOL, LOG_DEBUG, "Using reflexive UDP address from %s: %s port %s", from->name, address, port);
 379                                 sockaddr_t sa = str2sockaddr(address, port);
 380                                 update_node_udp(from, &sa);
 381                         }
 382
 383                         if(from->options & OPTION_PMTU_DISCOVERY)
 384                                 send_mtu_probe(from);
 385                 }
 386
 387                 return true;
 388         }
 389
 390         /* Check and lookup cipher and digest algorithms */
 391
 392         if(!cipher_open_by_nid(&from->outcipher, cipher)) {
 393                 logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses unknown cipher!", from->name, from->hostname);
 394                 return false;
 395         }
 396
 397         if(!digest_open_by_nid(&from->outdigest, digest, maclength)) {
 398                 logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses unknown digest!", from->name, from->hostname);
 399                 return false;
 400         }
 401
 402         if(maclength != digest_length(&from->outdigest)) {
 403                 logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses bogus MAC length!", from->name, from->hostname);
 404                 return false;
 405         }
 406
 407         /* Process key */
 408
 409         keylen = hex2bin(key, key, sizeof key);
 410
 411         if(keylen != cipher_keylength(&from->outcipher)) {
 412                 logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses wrong keylength!", from->name, from->hostname);
 413                 return true;
 414         }
 415
 416         /* Update our copy of the origin's packet key */
 417
 418         cipher_set_key(&from->outcipher, key, true);
 419         digest_set_key(&from->outdigest, key, keylen);
 420
 421         from->status.validkey = true;
 422         from->sent_seqno = 0;
 423
 424         if(*address && *port) {
 425                 logger(DEBUG_PROTOCOL, LOG_DEBUG, "Using reflexive UDP address from %s: %s port %s", from->name, address, port);
 426                 sockaddr_t sa = str2sockaddr(address, port);
 427                 update_node_udp(from, &sa);
 428         }
 429
 430         if(from->options & OPTION_PMTU_DISCOVERY)
 431                 send_mtu_probe(from);
 432
 433         return true;
 434 }