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_node_t *node = connection_list->head, *next; node; node = next) {
  44                 next = node->next;
  45                 connection_t *c = node->data;
  46                 if(c->status.active && c->node && c->node->status.reachable) {
  47                         if(!c->node->status.sptps)
  48                                 send_ans_key(c->node);
  49                 }
  50         }
  51
  52         /* Force key exchange for connections using SPTPS */
  53
  54         if(experimental) {
  55                 for(splay_node_t *node = node_tree->head; node; node = node->next) {
  56                         node_t *n = node->data;
  57                         if(n->status.reachable && n->status.validkey && n->status.sptps)
  58                                 sptps_force_kex(&n->sptps);
  59                 }
  60         }
  61 }
  62
  63 bool key_changed_h(connection_t *c, const char *request) {
  64         char name[MAX_STRING_SIZE];
  65         node_t *n;
  66
  67         if(sscanf(request, "%*d %*x " MAX_STRING, name) != 1) {
  68                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s)", "KEY_CHANGED",
  69                            c->name, c->hostname);
  70                 return false;
  71         }
  72
  73         if(seen_request(request))
  74                 return true;
  75
  76         n = lookup_node(name);
  77
  78         if(!n) {
  79                 logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) origin %s which does not exist",
  80                            "KEY_CHANGED", c->name, c->hostname, name);
  81                 return true;
  82         }
  83
  84         if(!n->status.sptps) {
  85                 n->status.validkey = false;
  86                 n->last_req_key = 0;
  87         }
  88
  89         /* Tell the others */
  90
  91         if(!tunnelserver)
  92                 forward_request(c, request);
  93
  94         return true;
  95 }
  96
  97 static bool send_initial_sptps_data(void *handle, uint8_t type, const char *data, size_t len) {
  98         node_t *to = handle;
  99         to->sptps.send_data = send_sptps_data;
 100         char buf[len * 4 / 3 + 5];
 101         b64encode(data, buf, len);
 102         return send_request(to->nexthop->connection, "%d %s %s %d %s", REQ_KEY, myself->name, to->name, REQ_KEY, buf);
 103 }
 104
 105 bool send_req_key(node_t *to) {
 106         if(to->status.sptps) {
 107                 if(!node_read_ecdsa_public_key(to)) {
 108                         logger(DEBUG_PROTOCOL, LOG_DEBUG, "No ECDSA key known for %s (%s)", to->name, to->hostname);
 109                         send_request(to->nexthop->connection, "%d %s %s %d", REQ_KEY, myself->name, to->name, REQ_PUBKEY);
 110                         return true;
 111                 }
 112                 char label[25 + strlen(myself->name) + strlen(to->name)];
 113                 snprintf(label, sizeof label, "tinc UDP key expansion %s %s", myself->name, to->name);
 114                 sptps_stop(&to->sptps);
 115                 to->status.validkey = false;
 116                 to->status.waitingforkey = true;
 117                 to->last_req_key = time(NULL);
 118                 to->incompression = myself->incompression;
 119                 return sptps_start(&to->sptps, to, true, true, myself->connection->ecdsa, to->ecdsa, label, sizeof label, send_initial_sptps_data, receive_sptps_record);
 120         }
 121
 122         return send_request(to->nexthop->connection, "%d %s %s", REQ_KEY, myself->name, to->name);
 123 }
 124
 125 /* REQ_KEY is overloaded to allow arbitrary requests to be routed between two nodes. */
 126
 127 static bool req_key_ext_h(connection_t *c, const char *request, node_t *from, int reqno) {
 128         switch(reqno) {
 129                 case REQ_PUBKEY: {
 130                         char *pubkey = ecdsa_get_base64_public_key(&myself->connection->ecdsa);
 131                         send_request(from->nexthop->connection, "%d %s %s %d %s", REQ_KEY, myself->name, from->name, ANS_PUBKEY, pubkey);
 132                         free(pubkey);
 133                         return true;
 134                 }
 135
 136                 case ANS_PUBKEY: {
 137                         if(node_read_ecdsa_public_key(from)) {
 138                                 logger(DEBUG_PROTOCOL, LOG_WARNING, "Got ANS_PUBKEY from %s (%s) even though we already have his pubkey", from->name, from->hostname);
 139                                 return true;
 140                         }
 141
 142                         char pubkey[MAX_STRING_SIZE];
 143                         if(sscanf(request, "%*d %*s %*s %*d " MAX_STRING, pubkey) != 1 || !ecdsa_set_base64_public_key(&from->ecdsa, pubkey)) {
 144                                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "ANS_PUBKEY", from->name, from->hostname, "invalid pubkey");
 145                                 return true;
 146                         }
 147
 148                         logger(DEBUG_PROTOCOL, LOG_INFO, "Learned ECDSA public key from %s (%s)", from->name, from->hostname);
 149                         append_config_file(from->name, "ECDSAPublicKey", pubkey);
 150                         return true;
 151                 }
 152
 153                 case REQ_KEY: {
 154                         if(!node_read_ecdsa_public_key(from)) {
 155                                 logger(DEBUG_PROTOCOL, LOG_DEBUG, "No ECDSA key known for %s (%s)", from->name, from->hostname);
 156                                 send_request(from->nexthop->connection, "%d %s %s %d", REQ_KEY, myself->name, from->name, REQ_PUBKEY);
 157                                 return true;
 158                         }
 159                 }
 160
 161                 case REQ_SPTPS: {
 162                         char buf[MAX_STRING_SIZE];
 163                         if(sscanf(request, "%*d %*s %*s %*d " MAX_STRING, buf) != 1) {
 164                                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "REQ_KEY", from->name, from->hostname, "invalid SPTPS data");
 165                                 return true;
 166                         }
 167                         int len = b64decode(buf, buf, strlen(buf));
 168
 169
 170                         char label[25 + strlen(from->name) + strlen(myself->name)];
 171                         snprintf(label, sizeof label, "tinc UDP key expansion %s %s", from->name, myself->name);
 172                         sptps_stop(&from->sptps);
 173                         from->status.validkey = false;
 174                         from->status.waitingforkey = true;
 175                         from->last_req_key = time(NULL);
 176                         sptps_start(&from->sptps, from, false, true, myself->connection->ecdsa, from->ecdsa, label, sizeof label, send_sptps_data, receive_sptps_record);
 177                         sptps_receive_data(&from->sptps, buf, len);
 178                         return true;
 179                 }
 180
 181                 case REQ_PACKET: {
 182                         if(!from->status.validkey) {
 183                                 logger(DEBUG_PROTOCOL, LOG_ERR, "Got REQ_PACKET from %s (%s) but we don't have a valid key yet", from->name, from->hostname);
 184                                 return true;
 185                         }
 186
 187                         char buf[MAX_STRING_SIZE];
 188                         if(sscanf(request, "%*d %*s %*s %*d " MAX_STRING, buf) != 1) {
 189                                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "REQ_KEY", from->name, from->hostname, "invalid SPTPS data");
 190                                 return true;
 191                         }
 192                         int len = b64decode(buf, buf, strlen(buf));
 193                         sptps_receive_data(&from->sptps, buf, len);
 194                         return true;
 195                 }
 196
 197                 default:
 198                         logger(DEBUG_ALWAYS, LOG_ERR, "Unknown extended REQ_KEY request from %s (%s): %s", from->name, from->hostname, request);
 199                         return true;
 200         }
 201 }
 202
 203 bool req_key_h(connection_t *c, const char *request) {
 204         char from_name[MAX_STRING_SIZE];
 205         char to_name[MAX_STRING_SIZE];
 206         node_t *from, *to;
 207         int reqno = 0;
 208
 209         if(sscanf(request, "%*d " MAX_STRING " " MAX_STRING " %d", from_name, to_name, &reqno) < 2) {
 210                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s)", "REQ_KEY", c->name,
 211                            c->hostname);
 212                 return false;
 213         }
 214
 215         if(!check_id(from_name) || !check_id(to_name)) {
 216                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "REQ_KEY", c->name, c->hostname, "invalid name");
 217                 return false;
 218         }
 219
 220         from = lookup_node(from_name);
 221
 222         if(!from) {
 223                 logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) origin %s which does not exist in our connection list",
 224                            "REQ_KEY", c->name, c->hostname, from_name);
 225                 return true;
 226         }
 227
 228         to = lookup_node(to_name);
 229
 230         if(!to) {
 231                 logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) destination %s which does not exist in our connection list",
 232                            "REQ_KEY", c->name, c->hostname, to_name);
 233                 return true;
 234         }
 235
 236         /* Check if this key request is for us */
 237
 238         if(to == myself) {                      /* Yes */
 239                 /* Is this an extended REQ_KEY message? */
 240                 if(experimental && reqno)
 241                         return req_key_ext_h(c, request, from, reqno);
 242
 243                 /* No, just send our key back */
 244                 send_ans_key(from);
 245         } else {
 246                 if(tunnelserver)
 247                         return true;
 248
 249                 if(!to->status.reachable) {
 250                         logger(DEBUG_PROTOCOL, LOG_WARNING, "Got %s from %s (%s) destination %s which is not reachable",
 251                                 "REQ_KEY", c->name, c->hostname, to_name);
 252                         return true;
 253                 }
 254
 255                 send_request(to->nexthop->connection, "%s", request);
 256         }
 257
 258         return true;
 259 }
 260
 261 bool send_ans_key(node_t *to) {
 262         if(to->status.sptps)
 263                 abort();
 264
 265         size_t keylen = cipher_keylength(&myself->incipher);
 266         char key[keylen * 2 + 1];
 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         if(replaywin) memset(to->late, 0, replaywin);
 282
 283         return send_request(to->nexthop->connection, "%d %s %s %s %d %d %d %d", ANS_KEY,
 284                                                 myself->name, to->name, key,
 285                                                 cipher_get_nid(&to->incipher),
 286                                                 digest_get_nid(&to->indigest),
 287                                                 (int)digest_length(&to->indigest),
 288                                                 to->incompression);
 289 }
 290
 291 bool ans_key_h(connection_t *c, const char *request) {
 292         char from_name[MAX_STRING_SIZE];
 293         char to_name[MAX_STRING_SIZE];
 294         char key[MAX_STRING_SIZE];
 295         char address[MAX_STRING_SIZE] = "";
 296         char port[MAX_STRING_SIZE] = "";
 297         int cipher, digest, maclength, compression, keylen;
 298         node_t *from, *to;
 299
 300         if(sscanf(request, "%*d "MAX_STRING" "MAX_STRING" "MAX_STRING" %d %d %d %d "MAX_STRING" "MAX_STRING,
 301                 from_name, to_name, key, &cipher, &digest, &maclength,
 302                 &compression, address, port) < 7) {
 303                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s)", "ANS_KEY", c->name,
 304                            c->hostname);
 305                 return false;
 306         }
 307
 308         if(!check_id(from_name) || !check_id(to_name)) {
 309                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "ANS_KEY", c->name, c->hostname, "invalid name");
 310                 return false;
 311         }
 312
 313         from = lookup_node(from_name);
 314
 315         if(!from) {
 316                 logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) origin %s which does not exist in our connection list",
 317                            "ANS_KEY", c->name, c->hostname, from_name);
 318                 return true;
 319         }
 320
 321         to = lookup_node(to_name);
 322
 323         if(!to) {
 324                 logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) destination %s which does not exist in our connection list",
 325                            "ANS_KEY", c->name, c->hostname, to_name);
 326                 return true;
 327         }
 328
 329         /* Forward it if necessary */
 330
 331         if(to != myself) {
 332                 if(tunnelserver)
 333                         return true;
 334
 335                 if(!to->status.reachable) {
 336                         logger(DEBUG_ALWAYS, LOG_WARNING, "Got %s from %s (%s) destination %s which is not reachable",
 337                                    "ANS_KEY", c->name, c->hostname, to_name);
 338                         return true;
 339                 }
 340
 341                 if(!*address && from->address.sa.sa_family != AF_UNSPEC) {
 342                         char *address, *port;
 343                         logger(DEBUG_PROTOCOL, LOG_DEBUG, "Appending reflexive UDP address to ANS_KEY from %s to %s", from->name, to->name);
 344                         sockaddr2str(&from->address, &address, &port);
 345                         send_request(to->nexthop->connection, "%s %s %s", request, address, port);
 346                         free(address);
 347                         free(port);
 348                         return true;
 349                 }
 350
 351                 return send_request(to->nexthop->connection, "%s", request);
 352         }
 353
 354         /* Don't use key material until every check has passed. */
 355         from->status.validkey = false;
 356
 357         if(compression < 0 || compression > 11) {
 358                 logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses bogus compression level!", from->name, from->hostname);
 359                 return true;
 360         }
 361
 362         from->outcompression = compression;
 363
 364         /* SPTPS or old-style key exchange? */
 365
 366         if(from->status.sptps) {
 367                 char buf[strlen(key)];
 368                 int len = b64decode(key, buf, strlen(key));
 369
 370                 if(!sptps_receive_data(&from->sptps, buf, len))
 371                         logger(DEBUG_ALWAYS, LOG_ERR, "Error processing SPTPS data from %s (%s)", from->name, from->hostname);
 372
 373                 if(from->status.validkey) {
 374                         if(*address && *port) {
 375                                 logger(DEBUG_PROTOCOL, LOG_DEBUG, "Using reflexive UDP address from %s: %s port %s", from->name, address, port);
 376                                 sockaddr_t sa = str2sockaddr(address, port);
 377                                 update_node_udp(from, &sa);
 378                         }
 379
 380                         if(from->options & OPTION_PMTU_DISCOVERY)
 381                                 send_mtu_probe(from);
 382                 }
 383
 384                 return true;
 385         }
 386
 387         /* Check and lookup cipher and digest algorithms */
 388
 389         if(!cipher_open_by_nid(&from->outcipher, cipher)) {
 390                 logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses unknown cipher!", from->name, from->hostname);
 391                 return false;
 392         }
 393
 394         if(!digest_open_by_nid(&from->outdigest, digest, maclength)) {
 395                 logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses unknown digest!", from->name, from->hostname);
 396                 return false;
 397         }
 398
 399         if(maclength != digest_length(&from->outdigest)) {
 400                 logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses bogus MAC length!", from->name, from->hostname);
 401                 return false;
 402         }
 403
 404         /* Process key */
 405
 406         keylen = hex2bin(key, key, sizeof key);
 407
 408         if(keylen != cipher_keylength(&from->outcipher)) {
 409                 logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses wrong keylength!", from->name, from->hostname);
 410                 return true;
 411         }
 412
 413         /* Update our copy of the origin's packet key */
 414
 415         cipher_set_key(&from->outcipher, key, true);
 416         digest_set_key(&from->outdigest, key, keylen);
 417
 418         from->status.validkey = true;
 419         from->sent_seqno = 0;
 420
 421         if(*address && *port) {
 422                 logger(DEBUG_PROTOCOL, LOG_DEBUG, "Using reflexive UDP address from %s: %s port %s", from->name, address, port);
 423                 sockaddr_t sa = str2sockaddr(address, port);
 424                 update_node_udp(from, &sa);
 425         }
 426
 427         if(from->options & OPTION_PMTU_DISCOVERY)
 428                 send_mtu_probe(from);
 429
 430         return true;
 431 }