git.meshlink.io Git - meshlink/blob - src/protocol_key.c

   1 /*
   2     protocol_key.c -- handle the meta-protocol, key exchange
   3     Copyright (C) 2014 Guus Sliepen <guus@meshlink.io>
   4
   5     This program is free software; you can redistribute it and/or modify
   6     it under the terms of the GNU General Public License as published by
   7     the Free Software Foundation; either version 2 of the License, or
   8     (at your option) any later version.
   9
  10     This program is distributed in the hope that it will be useful,
  11     but WITHOUT ANY WARRANTY; without even the implied warranty of
  12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13     GNU General Public License for more details.
  14
  15     You should have received a copy of the GNU General Public License along
  16     with this program; if not, write to the Free Software Foundation, Inc.,
  17     51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  18 */
  19
  20 #include "system.h"
  21
  22 #include "cipher.h"
  23 #include "connection.h"
  24 #include "crypto.h"
  25 #include "logger.h"
  26 #include "net.h"
  27 #include "netutl.h"
  28 #include "node.h"
  29 #include "prf.h"
  30 #include "protocol.h"
  31 #include "sptps.h"
  32 #include "utils.h"
  33 #include "xalloc.h"
  34
  35 static bool mykeyused = false;
  36
  37 void send_key_changed(void) {
  38         send_request(everyone, "%d %x %s", KEY_CHANGED, rand(), myself->name);
  39
  40         /* Immediately send new keys to directly connected nodes to keep UDP mappings alive */
  41
  42         for list_each(connection_t, c, connection_list)
  43                 if(c->status.active && c->node && c->node->status.reachable && !c->node->status.sptps)
  44                         send_ans_key(c->node);
  45
  46         /* Force key exchange for connections using SPTPS */
  47
  48         if(experimental) {
  49                 for splay_each(node_t, n, node_tree)
  50                         if(n->status.reachable && n->status.validkey && n->status.sptps)
  51                                 sptps_force_kex(&n->sptps);
  52         }
  53 }
  54
  55 bool key_changed_h(connection_t *c, const char *request) {
  56         char name[MAX_STRING_SIZE];
  57         node_t *n;
  58
  59         if(sscanf(request, "%*d %*x " MAX_STRING, name) != 1) {
  60                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s)", "KEY_CHANGED",
  61                            c->name, c->hostname);
  62                 return false;
  63         }
  64
  65         if(seen_request(request))
  66                 return true;
  67
  68         n = lookup_node(name);
  69
  70         if(!n) {
  71                 logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) origin %s which does not exist",
  72                            "KEY_CHANGED", c->name, c->hostname, name);
  73                 return true;
  74         }
  75
  76         if(!n->status.sptps) {
  77                 n->status.validkey = false;
  78                 n->last_req_key = 0;
  79         }
  80
  81         /* Tell the others */
  82
  83         forward_request(c, request);
  84
  85         return true;
  86 }
  87
  88 static bool send_initial_sptps_data(void *handle, uint8_t type, const char *data, size_t len) {
  89         node_t *to = handle;
  90         to->sptps.send_data = send_sptps_data;
  91         char buf[len * 4 / 3 + 5];
  92         b64encode(data, buf, len);
  93         return send_request(to->nexthop->connection, "%d %s %s %d %s", REQ_KEY, myself->name, to->name, REQ_KEY, buf);
  94 }
  95
  96 bool send_req_key(node_t *to) {
  97         if(to->status.sptps) {
  98                 if(!node_read_ecdsa_public_key(to)) {
  99                         logger(DEBUG_PROTOCOL, LOG_DEBUG, "No ECDSA key known for %s (%s)", to->name, to->hostname);
 100                         send_request(to->nexthop->connection, "%d %s %s %d", REQ_KEY, myself->name, to->name, REQ_PUBKEY);
 101                         return true;
 102                 }
 103
 104                 if(to->sptps.label)
 105                         logger(DEBUG_ALWAYS, LOG_DEBUG, "send_req_key(%s) called while sptps->label != NULL!", to->name);
 106
 107                 char label[25 + strlen(myself->name) + strlen(to->name)];
 108                 snprintf(label, sizeof label, "tinc UDP key expansion %s %s", myself->name, to->name);
 109                 sptps_stop(&to->sptps);
 110                 to->status.validkey = false;
 111                 to->status.waitingforkey = true;
 112                 to->last_req_key = now.tv_sec;
 113                 to->incompression = myself->incompression;
 114                 return sptps_start(&to->sptps, to, true, true, myself->connection->ecdsa, to->ecdsa, label, sizeof label, send_initial_sptps_data, receive_sptps_record);
 115         }
 116
 117         return send_request(to->nexthop->connection, "%d %s %s", REQ_KEY, myself->name, to->name);
 118 }
 119
 120 /* REQ_KEY is overloaded to allow arbitrary requests to be routed between two nodes. */
 121
 122 static bool req_key_ext_h(connection_t *c, const char *request, node_t *from, int reqno) {
 123         switch(reqno) {
 124                 case REQ_PUBKEY: {
 125                         char *pubkey = ecdsa_get_base64_public_key(myself->connection->ecdsa);
 126                         send_request(from->nexthop->connection, "%d %s %s %d %s", REQ_KEY, myself->name, from->name, ANS_PUBKEY, pubkey);
 127                         free(pubkey);
 128                         return true;
 129                 }
 130
 131                 case ANS_PUBKEY: {
 132                         if(node_read_ecdsa_public_key(from)) {
 133                                 logger(DEBUG_PROTOCOL, LOG_WARNING, "Got ANS_PUBKEY from %s (%s) even though we already have his pubkey", from->name, from->hostname);
 134                                 return true;
 135                         }
 136
 137                         char pubkey[MAX_STRING_SIZE];
 138                         if(sscanf(request, "%*d %*s %*s %*d " MAX_STRING, pubkey) != 1 || !(from->ecdsa = ecdsa_set_base64_public_key(pubkey))) {
 139                                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "ANS_PUBKEY", from->name, from->hostname, "invalid pubkey");
 140                                 return true;
 141                         }
 142
 143                         logger(DEBUG_PROTOCOL, LOG_INFO, "Learned ECDSA public key from %s (%s)", from->name, from->hostname);
 144                         append_config_file(from->name, "ECDSAPublicKey", pubkey);
 145                         return true;
 146                 }
 147
 148                 case REQ_KEY: {
 149                         if(!node_read_ecdsa_public_key(from)) {
 150                                 logger(DEBUG_PROTOCOL, LOG_DEBUG, "No ECDSA key known for %s (%s)", from->name, from->hostname);
 151                                 send_request(from->nexthop->connection, "%d %s %s %d", REQ_KEY, myself->name, from->name, REQ_PUBKEY);
 152                                 return true;
 153                         }
 154
 155                         if(from->sptps.label)
 156                                 logger(DEBUG_ALWAYS, LOG_DEBUG, "Got REQ_KEY from %s while we already started a SPTPS session!", from->name);
 157
 158                         char buf[MAX_STRING_SIZE];
 159                         int len;
 160
 161                         if(sscanf(request, "%*d %*s %*s %*d " MAX_STRING, buf) != 1 || !(len = b64decode(buf, buf, strlen(buf)))) {
 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
 166                         char label[25 + strlen(from->name) + strlen(myself->name)];
 167                         snprintf(label, sizeof label, "tinc UDP key expansion %s %s", from->name, myself->name);
 168                         sptps_stop(&from->sptps);
 169                         from->status.validkey = false;
 170                         from->status.waitingforkey = true;
 171                         from->last_req_key = now.tv_sec;
 172                         sptps_start(&from->sptps, from, false, true, myself->connection->ecdsa, from->ecdsa, label, sizeof label, send_sptps_data, receive_sptps_record);
 173                         sptps_receive_data(&from->sptps, buf, len);
 174                         return true;
 175                 }
 176
 177                 case REQ_SPTPS: {
 178                         if(!from->status.validkey) {
 179                                 logger(DEBUG_PROTOCOL, LOG_ERR, "Got REQ_SPTPS from %s (%s) but we don't have a valid key yet", from->name, from->hostname);
 180                                 return true;
 181                         }
 182
 183                         char buf[MAX_STRING_SIZE];
 184                         int len;
 185                         if(sscanf(request, "%*d %*s %*s %*d " MAX_STRING, buf) != 1 || !(len = b64decode(buf, buf, strlen(buf)))) {
 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                         sptps_receive_data(&from->sptps, buf, len);
 190                         return true;
 191                 }
 192
 193                 default:
 194                         logger(DEBUG_ALWAYS, LOG_ERR, "Unknown extended REQ_KEY request from %s (%s): %s", from->name, from->hostname, request);
 195                         return true;
 196         }
 197 }
 198
 199 bool req_key_h(connection_t *c, const char *request) {
 200         char from_name[MAX_STRING_SIZE];
 201         char to_name[MAX_STRING_SIZE];
 202         node_t *from, *to;
 203         int reqno = 0;
 204
 205         if(sscanf(request, "%*d " MAX_STRING " " MAX_STRING " %d", from_name, to_name, &reqno) < 2) {
 206                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s)", "REQ_KEY", c->name,
 207                            c->hostname);
 208                 return false;
 209         }
 210
 211         if(!check_id(from_name) || !check_id(to_name)) {
 212                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "REQ_KEY", c->name, c->hostname, "invalid name");
 213                 return false;
 214         }
 215
 216         from = lookup_node(from_name);
 217
 218         if(!from) {
 219                 logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) origin %s which does not exist in our connection list",
 220                            "REQ_KEY", c->name, c->hostname, from_name);
 221                 return true;
 222         }
 223
 224         to = lookup_node(to_name);
 225
 226         if(!to) {
 227                 logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) destination %s which does not exist in our connection list",
 228                            "REQ_KEY", c->name, c->hostname, to_name);
 229                 return true;
 230         }
 231
 232         /* Check if this key request is for us */
 233
 234         if(to == myself) {                      /* Yes */
 235                 /* Is this an extended REQ_KEY message? */
 236                 if(experimental && reqno)
 237                         return req_key_ext_h(c, request, from, reqno);
 238
 239                 /* No, just send our key back */
 240                 send_ans_key(from);
 241         } else {
 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_close(to->incipher);
 262         digest_close(to->indigest);
 263
 264         to->incipher = cipher_open_by_nid(cipher_get_nid(myself->incipher));
 265         to->indigest = digest_open_by_nid(digest_get_nid(myself->indigest), digest_length(myself->indigest));
 266         to->incompression = myself->incompression;
 267
 268         if(!to->incipher || !to->indigest)
 269                 abort();
 270
 271         randomize(key, keylen);
 272         if(!cipher_set_key(to->incipher, key, false))
 273                 abort();
 274         if(!digest_set_key(to->indigest, key, keylen))
 275                 abort();
 276
 277         bin2hex(key, key, keylen);
 278
 279         // Reset sequence number and late packet window
 280         mykeyused = true;
 281         to->received_seqno = 0;
 282         to->received = 0;
 283         if(replaywin) memset(to->late, 0, replaywin);
 284
 285         return send_request(to->nexthop->connection, "%d %s %s %s %d %d %d %d", ANS_KEY,
 286                                                 myself->name, to->name, key,
 287                                                 cipher_get_nid(to->incipher),
 288                                                 digest_get_nid(to->indigest),
 289                                                 (int)digest_length(to->indigest),
 290                                                 to->incompression);
 291 }
 292
 293 bool ans_key_h(connection_t *c, const char *request) {
 294         char from_name[MAX_STRING_SIZE];
 295         char to_name[MAX_STRING_SIZE];
 296         char key[MAX_STRING_SIZE];
 297         char address[MAX_STRING_SIZE] = "";
 298         char port[MAX_STRING_SIZE] = "";
 299         int cipher, digest, maclength, compression, keylen;
 300         node_t *from, *to;
 301
 302         if(sscanf(request, "%*d "MAX_STRING" "MAX_STRING" "MAX_STRING" %d %d %d %d "MAX_STRING" "MAX_STRING,
 303                 from_name, to_name, key, &cipher, &digest, &maclength,
 304                 &compression, address, port) < 7) {
 305                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s)", "ANS_KEY", c->name,
 306                            c->hostname);
 307                 return false;
 308         }
 309
 310         if(!check_id(from_name) || !check_id(to_name)) {
 311                 logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "ANS_KEY", c->name, c->hostname, "invalid name");
 312                 return false;
 313         }
 314
 315         from = lookup_node(from_name);
 316
 317         if(!from) {
 318                 logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) origin %s which does not exist in our connection list",
 319                            "ANS_KEY", c->name, c->hostname, from_name);
 320                 return true;
 321         }
 322
 323         to = lookup_node(to_name);
 324
 325         if(!to) {
 326                 logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) destination %s which does not exist in our connection list",
 327                            "ANS_KEY", c->name, c->hostname, to_name);
 328                 return true;
 329         }
 330
 331         /* Forward it if necessary */
 332
 333         if(to != myself) {
 334                 if(!to->status.reachable) {
 335                         logger(DEBUG_ALWAYS, LOG_WARNING, "Got %s from %s (%s) destination %s which is not reachable",
 336                                    "ANS_KEY", c->name, c->hostname, to_name);
 337                         return true;
 338                 }
 339
 340                 if(!*address && from->address.sa.sa_family != AF_UNSPEC) {
 341                         char *address, *port;
 342                         logger(DEBUG_PROTOCOL, LOG_DEBUG, "Appending reflexive UDP address to ANS_KEY from %s to %s", from->name, to->name);
 343                         sockaddr2str(&from->address, &address, &port);
 344                         send_request(to->nexthop->connection, "%s %s %s", request, address, port);
 345                         free(address);
 346                         free(port);
 347                         return true;
 348                 }
 349
 350                 return send_request(to->nexthop->connection, "%s", request);
 351         }
 352
 353         /* Don't use key material until every check has passed. */
 354         cipher_close(from->outcipher);
 355         digest_close(from->outdigest);
 356         from->status.validkey = false;
 357
 358         if(compression < 0 || compression > 11) {
 359                 logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses bogus compression level!", from->name, from->hostname);
 360                 return true;
 361         }
 362
 363         from->outcompression = compression;
 364
 365         /* SPTPS or old-style key exchange? */
 366
 367         if(from->status.sptps) {
 368                 char buf[strlen(key)];
 369                 int len = b64decode(key, buf, strlen(key));
 370
 371                 if(!len || !sptps_receive_data(&from->sptps, buf, len))
 372                         logger(DEBUG_ALWAYS, LOG_ERR, "Error processing SPTPS data from %s (%s)", from->name, from->hostname);
 373
 374                 if(from->status.validkey) {
 375                         if(*address && *port) {
 376                                 logger(DEBUG_PROTOCOL, LOG_DEBUG, "Using reflexive UDP address from %s: %s port %s", from->name, address, port);
 377                                 sockaddr_t sa = str2sockaddr(address, port);
 378                                 update_node_udp(from, &sa);
 379                         }
 380
 381                         if(from->options & OPTION_PMTU_DISCOVERY && !(from->options & OPTION_TCPONLY))
 382                                 send_mtu_probe(from);
 383                 }
 384
 385                 return true;
 386         }
 387
 388         /* Check and lookup cipher and digest algorithms */
 389
 390         if(cipher) {
 391                 if(!(from->outcipher = cipher_open_by_nid(cipher))) {
 392                         logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses unknown cipher!", from->name, from->hostname);
 393                         return false;
 394                 }
 395         } else {
 396                 from->outcipher = NULL;
 397         }
 398
 399         if(digest) {
 400                 if(!(from->outdigest = digest_open_by_nid(digest, maclength))) {
 401                         logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses unknown digest!", from->name, from->hostname);
 402                         return false;
 403                 }
 404         } else {
 405                 from->outdigest = NULL;
 406         }
 407
 408         if(maclength != digest_length(from->outdigest)) {
 409                 logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses bogus MAC length!", from->name, from->hostname);
 410                 return false;
 411         }
 412
 413         /* Process key */
 414
 415         keylen = hex2bin(key, key, sizeof key);
 416
 417         if(keylen != cipher_keylength(from->outcipher)) {
 418                 logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses wrong keylength!", from->name, from->hostname);
 419                 return true;
 420         }
 421
 422         /* Update our copy of the origin's packet key */
 423
 424         if(!cipher_set_key(from->outcipher, key, true))
 425                 return false;
 426         if(!digest_set_key(from->outdigest, key, keylen))
 427                 return false;
 428
 429         from->status.validkey = true;
 430         from->sent_seqno = 0;
 431
 432         if(*address && *port) {
 433                 logger(DEBUG_PROTOCOL, LOG_DEBUG, "Using reflexive UDP address from %s: %s port %s", from->name, address, port);
 434                 sockaddr_t sa = str2sockaddr(address, port);
 435                 update_node_udp(from, &sa);
 436         }
 437
 438         if(from->options & OPTION_PMTU_DISCOVERY && !(from->options & OPTION_TCPONLY))
 439                 send_mtu_probe(from);
 440
 441         return true;
 442 }