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                   2000-2009 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
  17     along with this program; if not, write to the Free Software
  18     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  19
  20     $Id$
  21 */
  22
  23 #include "system.h"
  24
  25 #include <openssl/evp.h>
  26 #include <openssl/err.h>
  27 #include <openssl/rand.h>
  28
  29 #include "avl_tree.h"
  30 #include "connection.h"
  31 #include "logger.h"
  32 #include "net.h"
  33 #include "netutl.h"
  34 #include "node.h"
  35 #include "protocol.h"
  36 #include "utils.h"
  37 #include "xalloc.h"
  38
  39 bool mykeyused = false;
  40
  41 bool send_key_changed()
  42 {
  43         cp();
  44
  45         /* Only send this message if some other daemon requested our key previously.
  46            This reduces unnecessary key_changed broadcasts.
  47          */
  48
  49         if(!mykeyused)
  50                 return true;
  51
  52         return send_request(broadcast, "%d %lx %s", KEY_CHANGED, random(), myself->name);
  53 }
  54
  55 bool key_changed_h(connection_t *c)
  56 {
  57         char name[MAX_STRING_SIZE];
  58         node_t *n;
  59
  60         cp();
  61
  62         if(sscanf(c->buffer, "%*d %*x " MAX_STRING, name) != 1) {
  63                 logger(LOG_ERR, _("Got bad %s from %s (%s)"), "KEY_CHANGED",
  64                            c->name, c->hostname);
  65                 return false;
  66         }
  67
  68         if(seen_request(c->buffer))
  69                 return true;
  70
  71         n = lookup_node(name);
  72
  73         if(!n) {
  74                 logger(LOG_ERR, _("Got %s from %s (%s) origin %s which does not exist"),
  75                            "KEY_CHANGED", c->name, c->hostname, name);
  76                 return false;
  77         }
  78
  79         n->status.validkey = false;
  80         n->status.waitingforkey = false;
  81
  82         /* Tell the others */
  83
  84         if(!tunnelserver)
  85                 forward_request(c);
  86
  87         return true;
  88 }
  89
  90 bool send_req_key(node_t *to)
  91 {
  92         cp();
  93
  94         return send_request(to->nexthop->connection, "%d %s %s", REQ_KEY, myself->name, to->name);
  95 }
  96
  97 bool req_key_h(connection_t *c)
  98 {
  99         char from_name[MAX_STRING_SIZE];
 100         char to_name[MAX_STRING_SIZE];
 101         node_t *from, *to;
 102
 103         cp();
 104
 105         if(sscanf(c->buffer, "%*d " MAX_STRING " " MAX_STRING, from_name, to_name) != 2) {
 106                 logger(LOG_ERR, _("Got bad %s from %s (%s)"), "REQ_KEY", c->name,
 107                            c->hostname);
 108                 return false;
 109         }
 110
 111         from = lookup_node(from_name);
 112
 113         if(!from) {
 114                 logger(LOG_ERR, _("Got %s from %s (%s) origin %s which does not exist in our connection list"),
 115                            "REQ_KEY", c->name, c->hostname, from_name);
 116                 return false;
 117         }
 118
 119         to = lookup_node(to_name);
 120
 121         if(!to) {
 122                 logger(LOG_ERR, _("Got %s from %s (%s) destination %s which does not exist in our connection list"),
 123                            "REQ_KEY", c->name, c->hostname, to_name);
 124                 return false;
 125         }
 126
 127         /* Check if this key request is for us */
 128
 129         if(to == myself) {                      /* Yes, send our own key back */
 130                 mykeyused = true;
 131                 from->received_seqno = 0;
 132                 memset(from->late, 0, sizeof(from->late));
 133                 send_ans_key(from);
 134         } else {
 135                 if(tunnelserver)
 136                         return false;
 137
 138                 if(!to->status.reachable) {
 139                         logger(LOG_WARNING, _("Got %s from %s (%s) destination %s which is not reachable"),
 140                                 "REQ_KEY", c->name, c->hostname, to_name);
 141                         return true;
 142                 }
 143
 144                 send_request(to->nexthop->connection, "%s", c->buffer);
 145         }
 146
 147         return true;
 148 }
 149
 150 bool send_ans_key(node_t *to)
 151 {
 152         char *key;
 153
 154         cp();
 155
 156         if(!to->inkey) {
 157                 to->incipher = myself->incipher;
 158                 to->inkeylength = myself->inkeylength;
 159                 to->indigest = myself->indigest;
 160                 to->incompression = myself->incompression;
 161                 to->inkey = xmalloc(to->inkeylength);
 162
 163                 RAND_pseudo_bytes((unsigned char *)to->inkey, to->inkeylength);
 164                 if(to->incipher)
 165                         EVP_DecryptInit_ex(&packet_ctx, to->incipher, NULL, (unsigned char *)to->inkey, (unsigned char *)to->inkey + to->incipher->key_len);
 166         }
 167
 168         key = alloca(2 * to->inkeylength + 1);
 169         bin2hex(to->inkey, key, to->inkeylength);
 170         key[to->outkeylength * 2] = '\0';
 171
 172         return send_request(to->nexthop->connection, "%d %s %s %s %d %d %d %d", ANS_KEY,
 173                         myself->name, to->name, key,
 174                         to->incipher ? to->incipher->nid : 0,
 175                         to->indigest ? to->indigest->type : 0, to->inmaclength,
 176                         to->incompression);
 177 }
 178
 179 bool ans_key_h(connection_t *c)
 180 {
 181         char from_name[MAX_STRING_SIZE];
 182         char to_name[MAX_STRING_SIZE];
 183         char key[MAX_STRING_SIZE];
 184         int cipher, digest, maclength, compression;
 185         node_t *from, *to;
 186
 187         cp();
 188
 189         if(sscanf(c->buffer, "%*d "MAX_STRING" "MAX_STRING" "MAX_STRING" %d %d %d %d",
 190                 from_name, to_name, key, &cipher, &digest, &maclength,
 191                 &compression) != 7) {
 192                 logger(LOG_ERR, _("Got bad %s from %s (%s)"), "ANS_KEY", c->name,
 193                            c->hostname);
 194                 return false;
 195         }
 196
 197         from = lookup_node(from_name);
 198
 199         if(!from) {
 200                 logger(LOG_ERR, _("Got %s from %s (%s) origin %s which does not exist in our connection list"),
 201                            "ANS_KEY", c->name, c->hostname, from_name);
 202                 return false;
 203         }
 204
 205         to = lookup_node(to_name);
 206
 207         if(!to) {
 208                 logger(LOG_ERR, _("Got %s from %s (%s) destination %s which does not exist in our connection list"),
 209                            "ANS_KEY", c->name, c->hostname, to_name);
 210                 return false;
 211         }
 212
 213         /* Forward it if necessary */
 214
 215         if(to != myself) {
 216                 if(tunnelserver)
 217                         return false;
 218
 219                 if(!to->status.reachable) {
 220                         logger(LOG_WARNING, _("Got %s from %s (%s) destination %s which is not reachable"),
 221                                 "ANS_KEY", c->name, c->hostname, to_name);
 222                         return true;
 223                 }
 224
 225                 return send_request(to->nexthop->connection, "%s", c->buffer);
 226         }
 227
 228         /* Update our copy of the origin's packet key */
 229
 230         if(from->outkey)
 231                 free(from->outkey);
 232
 233         from->outkey = xstrdup(key);
 234         from->outkeylength = strlen(key) / 2;
 235         hex2bin(from->outkey, from->outkey, from->outkeylength);
 236         from->outkey[from->outkeylength] = '\0';
 237
 238         from->status.validkey = true;
 239         from->status.waitingforkey = false;
 240         from->sent_seqno = 0;
 241
 242         /* Check and lookup cipher and digest algorithms */
 243
 244         if(cipher) {
 245                 from->outcipher = EVP_get_cipherbynid(cipher);
 246
 247                 if(!from->outcipher) {
 248                         logger(LOG_ERR, _("Node %s (%s) uses unknown cipher!"), from->name,
 249                                    from->hostname);
 250                         return false;
 251                 }
 252
 253                 if(from->outkeylength != from->outcipher->key_len + from->outcipher->iv_len) {
 254                         logger(LOG_ERR, _("Node %s (%s) uses wrong keylength!"), from->name,
 255                                    from->hostname);
 256                         return false;
 257                 }
 258         } else {
 259                 from->outcipher = NULL;
 260         }
 261
 262         from->outmaclength = maclength;
 263
 264         if(digest) {
 265                 from->outdigest = EVP_get_digestbynid(digest);
 266
 267                 if(!from->outdigest) {
 268                         logger(LOG_ERR, _("Node %s (%s) uses unknown digest!"), from->name,
 269                                    from->hostname);
 270                         return false;
 271                 }
 272
 273                 if(from->outmaclength > from->outdigest->md_size || from->outmaclength < 0) {
 274                         logger(LOG_ERR, _("Node %s (%s) uses bogus MAC length!"),
 275                                    from->name, from->hostname);
 276                         return false;
 277                 }
 278         } else {
 279                 from->outdigest = NULL;
 280         }
 281
 282         if(compression < 0 || compression > 11) {
 283                 logger(LOG_ERR, _("Node %s (%s) uses bogus compression level!"), from->name, from->hostname);
 284                 return false;
 285         }
 286
 287         from->outcompression = compression;
 288
 289         if(from->outcipher)
 290                 if(!EVP_EncryptInit_ex(&from->outctx, from->outcipher, NULL, (unsigned char *)from->outkey, (unsigned char *)from->outkey + from->outcipher->key_len)) {
 291                         logger(LOG_ERR, _("Error during initialisation of key from %s (%s): %s"),
 292                                         from->name, from->hostname, ERR_error_string(ERR_get_error(), NULL));
 293                         return false;
 294                 }
 295
 296         if(from->options & OPTION_PMTU_DISCOVERY && !from->mtuprobes)
 297                 send_mtu_probe(from);
 298
 299         return true;
 300 }