trusts/trusts_policy.c

   1 #include <stdio.h>
   2 #include <stdlib.h>
   3 #include <stdarg.h>
   4 #include <unistd.h>
   5 #include <sys/types.h>
   6 #include <sys/socket.h>
   7 #include <netinet/in.h>
   8
   9 #ifndef __USE_MISC
  10 #define __USE_MISC /* inet_aton */
  11 #endif
  12
  13 #include <arpa/inet.h>
  14 #include <sys/un.h>
  15 #include <sys/poll.h>
  16 #include <errno.h>
  17 #include <fcntl.h>
  18
  19 #include "../lib/hmac.h"
  20 #include "../core/events.h"
  21 #include "../core/schedule.h"
  22 #include "../core/nsmalloc.h"
  23 #include "../core/hooks.h"
  24 #include "../core/config.h"
  25 #include "../control/control.h"
  26 #include "../lib/irc_string.h"
  27 #include "../irc/irc.h"
  28 #include "../glines/glines.h"
  29 #include "trusts.h"
  30
  31 static int countext, enforcepolicy;
  32
  33 #define TRUSTBUFSIZE 8192
  34 #define TRUSTPASSLEN 128
  35 #define NONCELEN 16
  36
  37 #define STATE_UNAUTHED 0
  38 #define STATE_AUTHED 1
  39
  40 typedef struct trustsocket {
  41   int fd;
  42   int state;
  43   char buf[TRUSTBUFSIZE];
  44   unsigned char nonce[NONCELEN];
  45   int size;
  46   time_t timeout;
  47
  48   struct trustsocket *next;
  49 } trustsocket;
  50
  51 static trustsocket *tslist;
  52 static int listenerfd;
  53 static FILE *urandom;
  54
  55 typedef struct trustaccount {
  56   int used;
  57   char server[SERVERLEN+1];
  58   char password[TRUSTPASSLEN+1];
  59 } trustaccount;
  60
  61 trustaccount trustaccounts[MAXSERVERS];
  62
  63 static int checkconnectionth(const char *username, struct irc_in_addr *ip, trusthost *th, int hooknum, int usercountadjustment, char *message, size_t messagelen) {
  64   trustgroup *tg;
  65
  66   if(messagelen>0)
  67     message[0] = '\0';
  68
  69   if(!th)
  70     return POLICY_SUCCESS;
  71
  72   tg = th->group;
  73
  74   /*
  75    * the purpose of this logic is to avoid spam like this:
  76    * WARNING: tgX exceeded limit: 11 connected vs 10 max
  77    * (goes back down to 10)
  78    * WARNING: tgX exceeded limit: 11 connected vs 10 max
  79    */
  80
  81   if(hooknum == HOOK_TRUSTS_NEWNICK) {
  82     patricia_node_t *head, *node;
  83     int nodecount = 0;
  84
  85     head = refnode(iptree, ip, th->nodebits);
  86     PATRICIA_WALK(head, node)
  87     {
  88       nodecount += node->usercount;
  89     }
  90     PATRICIA_WALK_END;
  91     derefnode(iptree, head);
  92
  93     if(th->maxpernode && nodecount + usercountadjustment > th->maxpernode) {
  94       controlwall(NO_OPER, NL_TRUSTS, "Hard connection limit exceeded on subnet: %s (group: %s) %d connected, %d max - %senforced.", trusts_cidr2str(ip, th->nodebits), tg->name->content, nodecount, th->maxpernode, enforcepolicy?"":"not ");
  95       snprintf(message, messagelen, "Too many connections from your host (%s) - see http://www.quakenet.org/help/trusts/connection-limit for details.", IPtostr(*ip));
  96       return POLICY_FAILURE_NODECOUNT;
  97     }
  98
  99     if(tg->trustedfor && tg->count + usercountadjustment > tg->trustedfor) {
 100       if(tg->count > (long)tg->exts[countext]) {
 101         tg->exts[countext] = (void *)(long)tg->count;
 102
 103         controlwall(NO_OPER, NL_TRUSTS, "Hard connection limit exceeded: '%s', %d connected, %d max.", tg->name->content, tg->count, tg->trustedfor);
 104         snprintf(message, messagelen, "Too many connections from your trust (%s) - see http://www.quakenet.org/help/trusts/connection-limit for details.", IPtostr(*ip));
 105         return POLICY_FAILURE_GROUPCOUNT;
 106       }
 107
 108       snprintf(message, messagelen, "Trust has %d out of %d allowed connections.", tg->count + usercountadjustment, tg->trustedfor);
 109     }
 110
 111     if((tg->flags & TRUST_ENFORCE_IDENT) && (username[0] == '~')) {
 112       controlwall(NO_OPER, NL_TRUSTS, "Ident required: %s@%s (group: %s) - %senforced.", username, IPtostr(*ip), tg->name->content, enforcepolicy?"":"not ");
 113       snprintf(message, messagelen, "IDENTD required from your host (%s) - see http://www.quakenet.org/help/trusts/connection-limit for details.", IPtostr(*ip));
 114       return POLICY_FAILURE_IDENTD;
 115     }
 116
 117     if(tg->maxperident > 0) {
 118       int identcount = 0;
 119       trusthost *th2;
 120       nick *tnp;
 121
 122       for(th2=tg->hosts;th2;th2=th2->next) {
 123         for(tnp=th2->users;tnp;tnp=nextbytrust(tnp)) {
 124           if(!ircd_strcmp(tnp->ident, username))
 125             identcount++;
 126         }
 127       }
 128
 129       if(identcount + usercountadjustment > tg->maxperident) {
 130         controlwall(NO_OPER, NL_TRUSTS, "Hard ident limit exceeded: %s@%s (group: %s), %d connected, %d max - %senforced.", username, IPtostr(*ip), tg->name->content, identcount, tg->maxperident, enforcepolicy?"":"not ");
 131         snprintf(message, messagelen, "Too many connections from your username (%s@%s) - see http://www.quakenet.org/help/trusts/connection-limit for details.", username, IPtostr(*ip));
 132         return POLICY_FAILURE_IDENTCOUNT;
 133       }
 134     }
 135   } else {
 136     if(tg->count < tg->maxusage)
 137       tg->exts[countext] = (void *)(long)tg->count;
 138   }
 139
 140   return POLICY_SUCCESS;
 141 }
 142
 143 static int checkconnection(const char *username, struct irc_in_addr *ip, int hooknum, int cloneadjustment, char *message, size_t messagelen) {
 144   struct irc_in_addr ip_canonicalized;
 145   ip_canonicalize_tunnel(&ip_canonicalized, ip);
 146
 147   return checkconnectionth(username, &ip_canonicalized, th_getbyhost(ip), hooknum, cloneadjustment, message, messagelen);
 148 }
 149
 150 static int trustdowrite(trustsocket *sock, char *format, ...) {
 151   char buf[1024];
 152   va_list va;
 153   int r;
 154
 155   va_start(va, format);
 156   r = vsnprintf(buf, sizeof(buf), format, va);
 157   va_end(va);
 158
 159   if(r >= sizeof(buf))
 160     r = sizeof(buf) - 1;
 161
 162   buf[r] = '\n';
 163
 164   if(write(sock->fd, buf, r + 1) != r + 1)
 165     return 0;
 166   return 1;
 167 }
 168
 169 static int policycheck_auth(trustsocket *sock, const char *sequence_id, const char *username, const char *host) {
 170   char message[512];
 171   int verdict;
 172   struct irc_in_addr ip;
 173   unsigned char bits;
 174
 175   if(!ipmask_parse(host, &ip, &bits))
 176     return trustdowrite(sock, "PASS %s", sequence_id);
 177
 178   verdict = checkconnection(username, &ip, HOOK_TRUSTS_NEWNICK, 1, message, sizeof(message));
 179
 180   if (verdict == POLICY_SUCCESS) {
 181     if(message[0])
 182       return trustdowrite(sock, "PASS %s %s", sequence_id, message);
 183     else
 184       return trustdowrite(sock, "PASS %s", sequence_id);
 185   } else {
 186     return trustdowrite(sock, "KILL %s %s", sequence_id, message);
 187   }
 188 }
 189
 190 static int trustkillconnection(trustsocket *sock, char *reason) {
 191   trustdowrite(sock, "QUIT %s", reason);
 192   return 0;
 193 }
 194
 195 static void trustfreeconnection(trustsocket *sock) {
 196   trustsocket **pnext = &tslist;
 197
 198   for(trustsocket *ts=tslist;ts;ts=ts->next) {
 199     if(ts == sock) {
 200       deregisterhandler(sock->fd, 1);
 201       *pnext = sock->next;
 202       nsfree(POOL_TRUSTS, sock);
 203       break;
 204     }
 205
 206     pnext = &(sock->next);
 207   }
 208 }
 209
 210 static int handletrustauth(trustsocket *sock, char *server_name, char *mac) {
 211   int i;
 212   char *password = NULL;
 213   unsigned char digest[16];
 214   char noncehexbuf[NONCELEN * 2 + 1];
 215   char hexbuf[sizeof(digest) * 2 + 1];
 216
 217   for(i=0;i<MAXSERVERS;i++) {
 218     if(trustaccounts[i].used && strcmp(trustaccounts[i].server, server_name) == 0) {
 219       password = trustaccounts[i].password;
 220       break;
 221     }
 222   }
 223
 224   if (!password)
 225     return trustkillconnection(sock, "Invalid servername.");
 226
 227   hmacmd5 h;
 228   hmacmd5_init(&h, (unsigned char *)password, strlen(password));
 229   hmacmd5_update(&h, (unsigned char *)hmac_printhex(sock->nonce, noncehexbuf, NONCELEN), NONCELEN * 2);
 230   hmacmd5_final(&h, digest);
 231   if(hmac_strcmp(mac, hmac_printhex(digest, hexbuf, sizeof(digest))))
 232     return trustkillconnection(sock, "Bad MAC.");
 233
 234   sock->state = STATE_AUTHED;
 235   return trustdowrite(sock, "AUTHOK");
 236 }
 237
 238 #define MAXTOKENS 10
 239 static int handletrustline(trustsocket *sock, char *line) {
 240   char *command, *p, *lastpos;
 241   char *tokens[MAXTOKENS];
 242   int tokensfound = -1;
 243
 244   for(command=lastpos=p=line;*p;p++) {
 245     if(*p == ' ') {
 246       *p = '\0';
 247       if(tokensfound == MAXTOKENS)
 248         return trustkillconnection(sock, "too many tokens");
 249
 250       if(tokensfound >= 0) {
 251         tokens[tokensfound++] = lastpos;
 252       } else {
 253         tokensfound++;
 254       }
 255       lastpos = p + 1;
 256     }
 257   }
 258   if(lastpos != p) {
 259     if(tokensfound == MAXTOKENS)
 260       return trustkillconnection(sock, "too many tokens");
 261     tokens[tokensfound++] = lastpos;
 262   }
 263
 264   if(sock->state == STATE_UNAUTHED && !strcmp("AUTH", command)) {
 265     if(tokensfound != 2)
 266       return trustkillconnection(sock, "incorrect arg count for command.");
 267
 268     return handletrustauth(sock, tokens[0], tokens[1]);
 269   } else if(sock->state == STATE_AUTHED && !strcmp("CHECK", command)) {
 270     if(tokensfound != 3)
 271       return trustkillconnection(sock, "incorrect arg count for command.");
 272
 273     policycheck_auth(sock, tokens[0], tokens[1], tokens[2]);
 274     return 1;
 275   } else {
 276     Error("trusts_policy", ERR_WARNING, "Bad command: %s", command);
 277     return 0;
 278   }
 279 }
 280
 281 static trustsocket *findtrustsocketbyfd(int fd) {
 282   for(trustsocket *ts=tslist;ts;ts=ts->next)
 283     if(ts->fd==fd)
 284       return ts;
 285
 286   return NULL;
 287 }
 288
 289 static int handletrustclient(trustsocket *sock) {
 290   int r, remaining = TRUSTBUFSIZE - sock->size, i;
 291   char *lastpos, *c;
 292
 293   if(!remaining) {
 294     trustkillconnection(sock, "Buffer overflow.");
 295     return 0;
 296   }
 297
 298   r = read(sock->fd, sock->buf + sock->size, remaining);
 299   if(r <= 0)
 300     return 0;
 301
 302   sock->size+=r;
 303   lastpos = sock->buf;
 304
 305   for(c=sock->buf,i=0;i<sock->size;i++,c++) {
 306     if(*c != '\n')
 307       continue;
 308     *c = '\0';
 309     if(!handletrustline(sock, lastpos))
 310       return 0;
 311
 312     lastpos = c + 1; /* is this ok? */
 313   }
 314   sock->size-=lastpos - sock->buf;
 315   memmove(sock->buf, lastpos, sock->size);
 316
 317   return 1;
 318 }
 319
 320 static void processtrustclient(int fd, short events) {
 321   trustsocket *sock = findtrustsocketbyfd(fd);
 322
 323   if(!sock)
 324     return;
 325
 326   if(events & POLLIN)
 327     if(!handletrustclient(sock))
 328       trustfreeconnection(sock);
 329 }
 330
 331 static void trustdotimeout(void *arg) {
 332   time_t t = time(NULL);
 333   trustsocket **pnext, *next;
 334
 335   pnext = &tslist;
 336
 337   for(trustsocket *sock=tslist;sock;) {
 338     next = sock->next;
 339
 340     if(sock->state == STATE_UNAUTHED && t >= sock->timeout) {
 341       trustkillconnection(sock, "Auth timeout.");
 342       deregisterhandler(sock->fd, 1);
 343       *pnext = sock->next;
 344       nsfree(POOL_TRUSTS, sock);
 345     } else {
 346       pnext = &(sock->next);
 347     }
 348
 349     sock=next;
 350   }
 351 }
 352
 353 static void processtrustlistener(int fd, short events) {
 354   if(events & POLLIN) {
 355     trustsocket *sock;
 356     char buf[NONCELEN * 2 + 1];
 357
 358     int newfd = accept(fd, NULL, NULL), flags;
 359     if(newfd == -1)
 360       return;
 361
 362     flags = fcntl(newfd, F_GETFL, 0);
 363     if(flags < 0) {
 364       Error("trusts_policy", ERR_WARNING, "Unable to set socket non-blocking.");
 365       close(newfd);
 366       return;
 367     }
 368
 369     if(fcntl(fd, F_SETFL, flags|O_NONBLOCK) < 0) {
 370       Error("trusts_policy", ERR_WARNING, "Unable to set socket non-blocking.");
 371       close(newfd);
 372       return;
 373     }
 374
 375     registerhandler(newfd, POLLIN|POLLERR|POLLHUP, processtrustclient);
 376
 377     sock = nsmalloc(POOL_TRUSTS, sizeof(trustsocket));
 378     if(!sock) {
 379       deregisterhandler(newfd, 1);
 380       return;
 381     }
 382
 383     sock->fd = newfd;
 384     sock->next = tslist;
 385     tslist = sock;
 386
 387     if(fread((char *)sock->nonce, 1, NONCELEN, urandom) != NONCELEN) {
 388       Error("trusts_policy", ERR_WARNING, "Error getting random bytes.");
 389       deregisterhandler(newfd, 1);
 390       tslist = sock->next;
 391       nsfree(POOL_TRUSTS, sock);
 392     } else {
 393       sock->state = STATE_UNAUTHED;
 394       sock->size = 0;
 395       sock->timeout = time(NULL) + 30;
 396       if(!trustdowrite(sock, "AUTH %s", hmac_printhex(sock->nonce, buf, NONCELEN))) {
 397         Error("trusts_policy", ERR_WARNING, "Error writing auth to fd %d.", newfd);
 398         deregisterhandler(newfd, 1);
 399         tslist = sock->next;
 400         nsfree(POOL_TRUSTS, sock);
 401         return;
 402       }
 403     }
 404   }
 405 }
 406
 407 static int createlistenersock(int port) {
 408   struct sockaddr_in s;
 409   int fd;
 410   int optval;
 411
 412   memset(&s, 0, sizeof(struct sockaddr_in));
 413   s.sin_family = AF_INET;
 414   s.sin_addr.s_addr = INADDR_ANY;
 415   s.sin_port = htons(port);
 416
 417   fd = socket(PF_INET, SOCK_STREAM, 0);
 418   if(fd < 0) {
 419     Error("trusts_policy", ERR_WARNING, "Unable to get socket for trustfd.");
 420     return -1;
 421   }
 422
 423   optval = 1;
 424   setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &optval, sizeof(optval));
 425
 426   if(bind(fd, (struct sockaddr *)&s, sizeof(struct sockaddr_in)) < 0) {
 427     Error("trusts_policy", ERR_WARNING, "Unable to bind trustfd.");
 428     close(fd);
 429     return -1;
 430   }
 431
 432   if(listen(fd, 5) < 0) {
 433     Error("trusts_policy", ERR_WARNING, "Unable to listen on trustfd.");
 434     close(fd);
 435     return -1;
 436   }
 437
 438   registerhandler(fd, POLLIN, processtrustlistener);
 439
 440   return fd;
 441 }
 442
 443 static void policycheck_irc(int hooknum, void *arg) {
 444   void **args = arg;
 445   nick *np = args[0];
 446   long moving = (long)args[1];
 447   char message[512];
 448   int verdict;
 449
 450   if(moving)
 451     return;
 452
 453   verdict = checkconnectionth(np->ident, &np->p_nodeaddr, gettrusthost(np), hooknum, 0, message, sizeof(message));
 454
 455   if(!enforcepolicy)
 456     return;
 457
 458   switch (verdict) {
 459     case POLICY_FAILURE_NODECOUNT:
 460       glinebynick(np, POLICY_GLINE_DURATION, message, GLINE_IGNORE_TRUST);
 461       break;
 462     case POLICY_FAILURE_IDENTD:
 463       glinebyip("~*", &np->p_ipaddr, 128, POLICY_GLINE_DURATION, message, GLINE_ALWAYS_USER|GLINE_IGNORE_TRUST);
 464       break;
 465     case POLICY_FAILURE_IDENTCOUNT:
 466       glinebynick(np, POLICY_GLINE_DURATION, message, GLINE_ALWAYS_USER|GLINE_IGNORE_TRUST);
 467       break;
 468   }
 469 }
 470
 471 static int trusts_cmdtrustpolicy(void *source, int cargc, char **cargv) {
 472   nick *sender = source;
 473
 474   if(cargc < 1) {
 475     controlreply(sender, "Trust policy enforcement is currently %s.", enforcepolicy?"enabled":"disabled");
 476     return CMD_OK;
 477   }
 478
 479   enforcepolicy = atoi(cargv[0]);
 480   controlwall(NO_OPER, NL_TRUSTS, "%s %s trust policy enforcement.", controlid(sender), enforcepolicy?"enabled":"disabled");
 481   controlreply(sender, "Trust policy enforcement is now %s.", enforcepolicy?"enabled":"disabled");
 482
 483   return CMD_OK;
 484 }
 485
 486 void _init(void) {
 487   sstring *m;
 488   array *accts;
 489   int trustport;
 490
 491   countext = registertgext("count");
 492   if(countext == -1)
 493     return;
 494
 495   m = getconfigitem("trusts_policy", "enforcepolicy");
 496   if(m)
 497     enforcepolicy = atoi(m->content);
 498
 499   m = getconfigitem("trusts_policy", "trustport");
 500   if(m)
 501     trustport = atoi(m->content);
 502   else
 503     trustport = DEFAULT_TRUSTPORT;
 504
 505   if(trustport)
 506     listenerfd = createlistenersock(trustport);
 507
 508   accts = getconfigitems("trusts_policy", "server");
 509   if(!accts) {
 510     Error("trusts_policy", ERR_INFO, "No servers added.");
 511   } else {
 512     sstring **servers = (sstring **)(accts->content);
 513     int i;
 514     for(i=0;i<accts->cursi;i++) {
 515       char server[512];
 516       char *pos;
 517
 518       if(i>=MAXSERVERS) {
 519         Error("trusts_policy", ERR_INFO, "Too many servers specified.");
 520         break;
 521       }
 522
 523       strncpy(server, servers[i]->content, sizeof(server));
 524
 525       pos = strchr(server, ',');
 526
 527       if(!pos) {
 528         Error("trusts_policy", ERR_INFO, "Server line is missing password: %s", server);
 529         continue;
 530       }
 531
 532       *pos = '\0';
 533
 534       trustaccounts[i].used = 1;
 535       strncpy(trustaccounts[i].server, server, SERVERLEN);
 536       strncpy(trustaccounts[i].password, pos+1, TRUSTPASSLEN);
 537     }
 538   }
 539
 540   registerhook(HOOK_TRUSTS_NEWNICK, policycheck_irc);
 541   registerhook(HOOK_TRUSTS_LOSTNICK, policycheck_irc);
 542
 543   registercontrolhelpcmd("trustpolicy", NO_DEVELOPER, 1, trusts_cmdtrustpolicy, "Usage: trustpolicy ?1|0?\nEnables or disables policy enforcement. Shows current status when no parameter is specified.");
 544
 545   schedulerecurring(time(NULL)+1, 0, 5, trustdotimeout, NULL);
 546
 547   urandom = fopen("/dev/urandom", "rb");
 548   if(!urandom)
 549     Error("trusts_policy", ERR_ERROR, "Couldn't open /dev/urandom.");
 550 }
 551
 552 void _fini(void) {
 553   if(countext == -1)
 554     return;
 555
 556   releasetgext(countext);
 557
 558   deregisterhook(HOOK_TRUSTS_NEWNICK, policycheck_irc);
 559   deregisterhook(HOOK_TRUSTS_LOSTNICK, policycheck_irc);
 560
 561   deregistercontrolcmd("trustpolicy", trusts_cmdtrustpolicy);
 562
 563   deleteallschedules(trustdotimeout);
 564
 565   if (urandom)
 566     fclose(urandom);
 567 }