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