git.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 "splay_tree.h"
  24 #include "cipher.h"
  25 #include "connection.h"
  26 #include "crypto.h"
  27 #include "logger.h"
  28 #include "net.h"
  29 #include "netutl.h"
  30 #include "node.h"
  31 #include "prf.h"
  32 #include "protocol.h"
  33 #include "sptps.h"
  34 #include "utils.h"
  35 #include "xalloc.h"
  36
  37 static bool mykeyused = false;
  38
  39 void send_key_changed(void) {
  40         splay_node_t *node;
  41         connection_t *c;
  42
  43         send_request(everyone, "%d %x %s", KEY_CHANGED, rand(), myself->name);
  44
  45         /* Immediately send new keys to directly connected nodes to keep UDP mappings alive */
  46
  47         for(node = connection_tree->head; node; node = node->next) {
  48                 c = node->data;
  49                 if(c->status.active && c->node && c->node->status.reachable) {
  50                         if(!c->node->status.sptps)
  51                                 send_ans_key(c->node);
  52                 }
  53         }
  54
  55         /* Force key exchange for connections using SPTPS */
  56
  57         if(experimental) {
  58                 for(node = node_tree->head; node; node = node->next) {
  59                         node_t *n = node->data;
  60                         if(n->status.reachable && n->status.validkey && n->status.sptps)
  61                                 sptps_force_kex(&n->sptps);
  62                 }
  63         }
  64 }
  65
  66 bool key_changed_h(connection_t *c, const char *request) {
  67         char name[MAX_STRING_SIZE];
  68         node_t *n;
  69
  70         if(sscanf(request, "%*d %*x " MAX_STRING, name) != 1) {
  71                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s)", "KEY_CHANGED",
  72                            c->name, c->hostname);
  73                 return false;
  74         }
  75
  76         if(seen_request(request))
  77                 return true;
  78
  79         n = lookup_node(name);
  80
  81         if(!n) {
  82                 logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) origin %s which does not exist",
  83                            "KEY_CHANGED", c->name, c->hostname, name);
  84                 return true;
  85         }
  86
  87         if(!n->status.sptps) {
  88                 n->status.validkey = false;
  89                 n->last_req_key = 0;
  90         }
  91
  92         /* Tell the others */
  93
  94         if(!tunnelserver)
  95                 forward_request(c, request);
  96
  97         return true;
  98 }
  99
 100 static bool send_initial_sptps_data(void *handle, uint8_t type, const char *data, size_t len) {
 101         node_t *to = handle;
 102         to->sptps.send_data = send_sptps_data;
 103         char buf[len * 4 / 3 + 5];
 104         b64encode(data, buf, len);
 105         return send_request(to->nexthop->connection, "%d %s %s %d %s", REQ_KEY, myself->name, to->name, REQ_KEY, buf);
 106 }
 107
 108 bool send_req_key(node_t *to) {
 109         if(to->status.sptps) {
 110                 if(!node_read_ecdsa_public_key(to)) {
 111                         logger(DEBUG_ALWAYS, LOG_DEBUG, "No ECDSA key known for %s (%s)", to->name, to->hostname);
 112                         send_request(to->nexthop->connection, "%d %s %s %d", REQ_KEY, myself->name, to->name, REQ_PUBKEY);
 113                         return true;
 114                 }
 115                 char label[25 + strlen(myself->name) + strlen(to->name)];
 116                 snprintf(label, sizeof label, "tinc UDP key expansion %s %s", myself->name, to->name);
 117                 sptps_stop(&to->sptps);
 118                 to->status.validkey = false;
 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_ALWAYS, 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_ALWAYS, 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_ALWAYS, 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                         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                 default:
 180                         logger(DEBUG_ALWAYS, LOG_ERR, "Unknown extended REQ_KEY request from %s (%s): %s", from->name, from->hostname, request);
 181                         return true;
 182         }
 183 }
 184
 185 bool req_key_h(connection_t *c, const char *request) {
 186         char from_name[MAX_STRING_SIZE];
 187         char to_name[MAX_STRING_SIZE];
 188         node_t *from, *to;
 189         int reqno = 0;
 190
 191         if(sscanf(request, "%*d " MAX_STRING " " MAX_STRING " %d", from_name, to_name, &reqno) < 2) {
 192                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s)", "REQ_KEY", c->name,
 193                            c->hostname);
 194                 return false;
 195         }
 196
 197         if(!check_id(from_name) || !check_id(to_name)) {
 198                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "REQ_KEY", c->name, c->hostname, "invalid name");
 199                 return false;
 200         }
 201
 202         from = lookup_node(from_name);
 203
 204         if(!from) {
 205                 logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) origin %s which does not exist in our connection list",
 206                            "REQ_KEY", c->name, c->hostname, from_name);
 207                 return true;
 208         }
 209
 210         to = lookup_node(to_name);
 211
 212         if(!to) {
 213                 logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) destination %s which does not exist in our connection list",
 214                            "REQ_KEY", c->name, c->hostname, to_name);
 215                 return true;
 216         }
 217
 218         /* Check if this key request is for us */
 219
 220         if(to == myself) {                      /* Yes */
 221                 /* Is this an extended REQ_KEY message? */
 222                 if(experimental && reqno)
 223                         return req_key_ext_h(c, request, from, reqno);
 224
 225                 /* No, just send our key back */
 226                 send_ans_key(from);
 227         } else {
 228                 if(tunnelserver)
 229                         return true;
 230
 231                 if(!to->status.reachable) {
 232                         logger(DEBUG_ALWAYS, LOG_WARNING, "Got %s from %s (%s) destination %s which is not reachable",
 233                                 "REQ_KEY", c->name, c->hostname, to_name);
 234                         return true;
 235                 }
 236
 237                 send_request(to->nexthop->connection, "%s", request);
 238         }
 239
 240         return true;
 241 }
 242
 243 bool send_ans_key(node_t *to) {
 244         if(to->status.sptps)
 245                 abort();
 246
 247         size_t keylen = cipher_keylength(&myself->incipher);
 248         char key[keylen * 2 + 1];
 249
 250         cipher_open_by_nid(&to->incipher, cipher_get_nid(&myself->incipher));
 251         digest_open_by_nid(&to->indigest, digest_get_nid(&myself->indigest), digest_length(&myself->indigest));
 252         to->incompression = myself->incompression;
 253
 254         randomize(key, keylen);
 255         cipher_set_key(&to->incipher, key, false);
 256         digest_set_key(&to->indigest, key, keylen);
 257
 258         bin2hex(key, key, keylen);
 259
 260         // Reset sequence number and late packet window
 261         mykeyused = true;
 262         to->received_seqno = 0;
 263         if(replaywin) memset(to->late, 0, replaywin);
 264
 265         return send_request(to->nexthop->connection, "%d %s %s %s %d %d %d %d", ANS_KEY,
 266                                                 myself->name, to->name, key,
 267                                                 cipher_get_nid(&to->incipher),
 268                                                 digest_get_nid(&to->indigest),
 269                                                 (int)digest_length(&to->indigest),
 270                                                 to->incompression);
 271 }
 272
 273 bool ans_key_h(connection_t *c, const char *request) {
 274         char from_name[MAX_STRING_SIZE];
 275         char to_name[MAX_STRING_SIZE];
 276         char key[MAX_STRING_SIZE];
 277         char address[MAX_STRING_SIZE] = "";
 278         char port[MAX_STRING_SIZE] = "";
 279         int cipher, digest, maclength, compression, keylen;
 280         node_t *from, *to;
 281
 282         if(sscanf(request, "%*d "MAX_STRING" "MAX_STRING" "MAX_STRING" %d %d %d %d "MAX_STRING" "MAX_STRING,
 283                 from_name, to_name, key, &cipher, &digest, &maclength,
 284                 &compression, address, port) < 7) {
 285                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s)", "ANS_KEY", c->name,
 286                            c->hostname);
 287                 return false;
 288         }
 289
 290         if(!check_id(from_name) || !check_id(to_name)) {
 291                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "ANS_KEY", c->name, c->hostname, "invalid name");
 292                 return false;
 293         }
 294
 295         from = lookup_node(from_name);
 296
 297         if(!from) {
 298                 logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) origin %s which does not exist in our connection list",
 299                            "ANS_KEY", c->name, c->hostname, from_name);
 300                 return true;
 301         }
 302
 303         to = lookup_node(to_name);
 304
 305         if(!to) {
 306                 logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) destination %s which does not exist in our connection list",
 307                            "ANS_KEY", c->name, c->hostname, to_name);
 308                 return true;
 309         }
 310
 311         /* Forward it if necessary */
 312
 313         if(to != myself) {
 314                 if(tunnelserver)
 315                         return true;
 316
 317                 if(!to->status.reachable) {
 318                         logger(DEBUG_ALWAYS, LOG_WARNING, "Got %s from %s (%s) destination %s which is not reachable",
 319                                    "ANS_KEY", c->name, c->hostname, to_name);
 320                         return true;
 321                 }
 322
 323                 if(!*address && from->address.sa.sa_family != AF_UNSPEC) {
 324                         char *address, *port;
 325                         logger(DEBUG_PROTOCOL, LOG_DEBUG, "Appending reflexive UDP address to ANS_KEY from %s to %s", from->name, to->name);
 326                         sockaddr2str(&from->address, &address, &port);
 327                         send_request(to->nexthop->connection, "%s %s %s", request, address, port);
 328                         free(address);
 329                         free(port);
 330                         return true;
 331                 }
 332
 333                 return send_request(to->nexthop->connection, "%s", request);
 334         }
 335
 336         /* SPTPS or old-style key exchange? */
 337
 338         if(from->status.sptps) {
 339                 char buf[strlen(key)];
 340                 int len = b64decode(key, buf, strlen(key));
 341
 342                 if(!sptps_receive_data(&from->sptps, buf, len))
 343                         logger(DEBUG_ALWAYS, LOG_ERR, "Error processing SPTPS data from %s (%s)", from->name, from->hostname);
 344
 345                 if(from->status.validkey) {
 346                         if(*address && *port) {
 347                                 logger(DEBUG_PROTOCOL, LOG_DEBUG, "Using reflexive UDP address from %s: %s port %s", from->name, address, port);
 348                                 sockaddr_t sa = str2sockaddr(address, port);
 349                                 update_node_udp(from, &sa);
 350                         }
 351
 352                         if(from->options & OPTION_PMTU_DISCOVERY)
 353                                 send_mtu_probe(from);
 354                 }
 355
 356                 return true;
 357         }
 358
 359         /* Check and lookup cipher and digest algorithms */
 360
 361         if(!cipher_open_by_nid(&from->outcipher, cipher)) {
 362                 logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses unknown cipher!", from->name, from->hostname);
 363                 return false;
 364         }
 365
 366         if(!digest_open_by_nid(&from->outdigest, digest, maclength)) {
 367                 logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses unknown digest!", from->name, from->hostname);
 368                 return false;
 369         }
 370
 371         if(maclength != digest_length(&from->outdigest)) {
 372                 logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses bogus MAC length!", from->name, from->hostname);
 373                 return false;
 374         }
 375
 376         if(compression < 0 || compression > 11) {
 377                 logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses bogus compression level!", from->name, from->hostname);
 378                 return true;
 379         }
 380
 381         from->outcompression = compression;
 382
 383         /* Process key */
 384
 385         keylen = hex2bin(key, key, sizeof key);
 386
 387         if(keylen != cipher_keylength(&from->outcipher)) {
 388                 logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses wrong keylength!", from->name, from->hostname);
 389                 return true;
 390         }
 391
 392         /* Update our copy of the origin's packet key */
 393
 394         cipher_set_key(&from->outcipher, key, true);
 395         digest_set_key(&from->outdigest, key, keylen);
 396
 397         from->status.validkey = true;
 398         from->sent_seqno = 0;
 399
 400         if(*address && *port) {
 401                 logger(DEBUG_PROTOCOL, LOG_DEBUG, "Using reflexive UDP address from %s: %s port %s", from->name, address, port);
 402                 sockaddr_t sa = str2sockaddr(address, port);
 403                 update_node_udp(from, &sa);
 404         }
 405
 406         if(from->options & OPTION_PMTU_DISCOVERY)
 407                 send_mtu_probe(from);
 408
 409         return true;
 410 }