identd.c revision 1.27
1 /* $NetBSD: identd.c,v 1.27 2005/05/18 00:31:32 peter Exp $ */ 2 3 /* 4 * identd.c - TCP/IP Ident protocol server. 5 * 6 * This software is in the public domain. 7 * Written by Peter Postma <peter (at) NetBSD.org> 8 */ 9 10 #include <sys/types.h> 11 #include <sys/socket.h> 12 #include <sys/stat.h> 13 #include <sys/param.h> 14 #include <sys/sysctl.h> 15 16 #include <netinet/in.h> 17 #include <netinet/ip_var.h> 18 #include <netinet/tcp.h> 19 #include <netinet/tcp_timer.h> 20 #include <netinet/tcp_var.h> 21 22 #include <arpa/inet.h> 23 24 #include <ctype.h> 25 #include <err.h> 26 #include <errno.h> 27 #include <fcntl.h> 28 #include <grp.h> 29 #include <netdb.h> 30 #include <poll.h> 31 #include <pwd.h> 32 #include <signal.h> 33 #include <stdarg.h> 34 #include <stdio.h> 35 #include <stdlib.h> 36 #include <string.h> 37 #include <syslog.h> 38 #include <unistd.h> 39 40 #include "identd.h" 41 42 __RCSID("$NetBSD: identd.c,v 1.27 2005/05/18 00:31:32 peter Exp $"); 43 44 #define OPSYS_NAME "UNIX" 45 #define IDENT_SERVICE "auth" 46 #define TIMEOUT 30 /* seconds */ 47 48 static int idhandle(int, const char *, const char *, const char *, 49 const char *, struct sockaddr *, int); 50 static void idparse(int, int, int, const char *, const char *, const char *); 51 static void iderror(int, int, int, const char *); 52 static const char *gethost(struct sockaddr *); 53 static int *socketsetup(const char *, const char *, int); 54 static int ident_getuid(struct sockaddr_storage *, socklen_t, 55 struct sockaddr *, uid_t *); 56 static int sysctl_getuid(struct sockaddr_storage *, socklen_t, uid_t *); 57 static int sysctl_proxy_getuid(struct sockaddr_storage *, 58 struct sockaddr *, uid_t *); 59 static int forward(int, struct sockaddr *, int, int, int); 60 static int check_noident(const char *); 61 static int check_userident(const char *, char *, size_t); 62 static void random_string(char *, size_t); 63 static int change_format(const char *, struct passwd *, char *, size_t); 64 static void timeout_handler(int); 65 static void fatal(const char *); 66 static void die(const char *, ...); 67 68 static int bflag, eflag, fflag, Fflag, iflag, Iflag; 69 static int lflag, Lflag, nflag, Nflag, rflag; 70 71 /* NAT lookup function pointer. */ 72 static int (*nat_lookup)(struct sockaddr_storage *, struct sockaddr *, int *); 73 74 /* Packet filters. */ 75 static const struct { 76 const char *name; 77 int (*fn)(struct sockaddr_storage *, struct sockaddr *, int *); 78 } filters[] = { 79 #ifdef WITH_PF 80 { "pf", pf_natlookup }, 81 #endif 82 #ifdef WITH_IPF 83 { "ipfilter", ipf_natlookup }, 84 #endif 85 { NULL, NULL } 86 }; 87 88 int 89 main(int argc, char *argv[]) 90 { 91 int IPv4or6, ch, error, i, *socks, timeout; 92 const char *filter, *osname, *portno, *proxy; 93 char *address, *charset, *fmt, *p; 94 char user[LOGIN_NAME_MAX]; 95 struct addrinfo *ai, hints; 96 struct sockaddr *proxy_addr; 97 struct group *grp; 98 struct passwd *pw; 99 gid_t gid; 100 uid_t uid; 101 102 IPv4or6 = AF_UNSPEC; 103 osname = OPSYS_NAME; 104 portno = IDENT_SERVICE; 105 timeout = TIMEOUT; 106 nat_lookup = NULL; 107 proxy_addr = NULL; 108 filter = proxy = NULL; 109 address = charset = fmt = NULL; 110 uid = gid = 0; 111 bflag = eflag = fflag = Fflag = iflag = Iflag = 0; 112 lflag = Lflag = nflag = Nflag = rflag = 0; 113 114 /* Started from a tty? then run as daemon. */ 115 if (isatty(0)) 116 bflag = 1; 117 118 /* Parse command line arguments. */ 119 while ((ch = getopt(argc, argv, 120 "46a:bceF:f:g:IiL:lm:Nno:P:p:rt:u:")) != -1) { 121 switch (ch) { 122 case '4': 123 IPv4or6 = AF_INET; 124 break; 125 case '6': 126 IPv4or6 = AF_INET6; 127 break; 128 case 'a': 129 address = optarg; 130 break; 131 case 'b': 132 bflag = 1; 133 break; 134 case 'c': 135 charset = optarg; 136 break; 137 case 'e': 138 eflag = 1; 139 break; 140 case 'F': 141 Fflag = 1; 142 fmt = optarg; 143 break; 144 case 'f': 145 fflag = 1; 146 (void)strlcpy(user, optarg, sizeof(user)); 147 break; 148 case 'g': 149 gid = (gid_t)strtol(optarg, &p, 0); 150 if (*p != '\0') { 151 if ((grp = getgrnam(optarg)) != NULL) 152 gid = grp->gr_gid; 153 else 154 die("No such group `%s'", optarg); 155 } 156 break; 157 case 'I': 158 Iflag = 1; 159 /* FALLTHROUGH */ 160 case 'i': 161 iflag = 1; 162 break; 163 case 'L': 164 Lflag = 1; 165 (void)strlcpy(user, optarg, sizeof(user)); 166 break; 167 case 'l': 168 if (!lflag) 169 openlog("identd", LOG_PID, LOG_DAEMON); 170 lflag = 1; 171 break; 172 case 'm': 173 filter = optarg; 174 break; 175 case 'N': 176 Nflag = 1; 177 break; 178 case 'n': 179 nflag = 1; 180 break; 181 case 'o': 182 osname = optarg; 183 break; 184 case 'P': 185 proxy = optarg; 186 break; 187 case 'p': 188 portno = optarg; 189 break; 190 case 'r': 191 rflag = 1; 192 break; 193 case 't': 194 timeout = (int)strtol(optarg, &p, 0); 195 if (*p != '\0' || timeout < 1) 196 die("Invalid timeout value `%s'", optarg); 197 break; 198 case 'u': 199 uid = (uid_t)strtol(optarg, &p, 0); 200 if (*p != '\0') { 201 if ((pw = getpwnam(optarg)) != NULL) { 202 uid = pw->pw_uid; 203 gid = pw->pw_gid; 204 } else 205 die("No such user `%s'", optarg); 206 } 207 break; 208 default: 209 exit(EXIT_FAILURE); 210 } 211 } 212 213 /* Verify proxy address, if enabled. */ 214 if (proxy != NULL) { 215 (void)memset(&hints, 0, sizeof(hints)); 216 hints.ai_family = IPv4or6; 217 hints.ai_socktype = SOCK_STREAM; 218 error = getaddrinfo(proxy, NULL, &hints, &ai); 219 if (error != 0) 220 die("Bad proxy `%s': %s", proxy, gai_strerror(error)); 221 if (ai->ai_next != NULL) 222 die("Bad proxy `%s': resolves to multiple addresses", 223 proxy); 224 proxy_addr = ai->ai_addr; 225 } 226 227 /* Verify filter, if enabled. */ 228 if (filter != NULL) { 229 for (i = 0; filters[i].name != NULL; i++) { 230 if (strcasecmp(filter, filters[i].name) == 0) { 231 nat_lookup = filters[i].fn; 232 break; 233 } 234 } 235 if (nat_lookup == NULL) 236 die("Packet filter `%s' is not supported", filter); 237 } 238 239 /* Setup sockets when running in the background. */ 240 if (bflag) 241 socks = socketsetup(address, portno, IPv4or6); 242 243 /* Switch to another uid/gid? */ 244 if (gid && setgid(gid) == -1) 245 die("Failed to set GID to `%d': %s", gid, strerror(errno)); 246 if (uid && setuid(uid) == -1) 247 die("Failed to set UID to `%d': %s", uid, strerror(errno)); 248 249 /* 250 * When running as daemon: daemonize, setup pollfds and go into 251 * the mainloop. Otherwise, just read the input from stdin and 252 * let inetd handle the sockets. 253 */ 254 if (bflag) { 255 int fd, nfds, rv; 256 struct pollfd *rfds; 257 258 if (daemon(0, 0) < 0) 259 die("daemon: %s", strerror(errno)); 260 261 rfds = malloc(*socks * sizeof(struct pollfd)); 262 if (rfds == NULL) 263 fatal("malloc"); 264 nfds = *socks; 265 for (i = 0; i < nfds; i++) { 266 rfds[i].fd = socks[i+1]; 267 rfds[i].events = POLLIN; 268 rfds[i].revents = 0; 269 } 270 /* Mainloop for daemon. */ 271 for (;;) { 272 rv = poll(rfds, nfds, INFTIM); 273 if (rv < 0) { 274 if (errno == EINTR) 275 continue; 276 fatal("poll"); 277 } 278 for (i = 0; i < nfds; i++) { 279 if (rfds[i].revents & POLLIN) { 280 fd = accept(rfds[i].fd, NULL, NULL); 281 if (fd < 0) { 282 maybe_syslog(LOG_ERR, 283 "accept: %m"); 284 continue; 285 } 286 switch (fork()) { 287 case -1: /* error */ 288 maybe_syslog(LOG_ERR, 289 "fork: %m"); 290 (void)sleep(1); 291 break; 292 case 0: /* child */ 293 (void)idhandle(fd, charset, 294 fmt, osname, user, 295 proxy_addr, timeout); 296 _exit(EXIT_SUCCESS); 297 default: /* parent */ 298 (void)signal(SIGCHLD, SIG_IGN); 299 (void)close(fd); 300 } 301 } 302 } 303 } 304 } else 305 (void)idhandle(STDIN_FILENO, charset, fmt, osname, user, 306 proxy_addr, timeout); 307 308 return 0; 309 } 310 311 static int 312 idhandle(int fd, const char *charset, const char *fmt, const char *osname, 313 const char *user, struct sockaddr *proxy, int timeout) 314 { 315 struct sockaddr_storage ss[2]; 316 char userbuf[LOGIN_NAME_MAX]; /* actual user name (or numeric uid) */ 317 char idbuf[LOGIN_NAME_MAX]; /* name to be used in response */ 318 char buf[BUFSIZ], *p; 319 int n, lport, fport; 320 struct passwd *pw; 321 socklen_t len; 322 uid_t uid; 323 324 lport = fport = 0; 325 326 (void)strlcpy(idbuf, user, sizeof(idbuf)); 327 (void)signal(SIGALRM, timeout_handler); 328 (void)alarm(timeout); 329 330 /* Get foreign internet address. */ 331 len = sizeof(ss[0]); 332 if (getpeername(fd, (struct sockaddr *)&ss[0], &len) < 0) 333 fatal("getpeername"); 334 335 maybe_syslog(LOG_INFO, "Connection from %s", 336 gethost((struct sockaddr *)&ss[0])); 337 338 /* Get local internet address. */ 339 len = sizeof(ss[1]); 340 if (getsockname(fd, (struct sockaddr *)&ss[1], &len) < 0) 341 fatal("getsockname"); 342 343 /* Be sure to have the same address families. */ 344 if (ss[0].ss_family != ss[1].ss_family) { 345 maybe_syslog(LOG_ERR, "Different foreign/local address family"); 346 return 1; 347 } 348 349 /* Receive data from the client. */ 350 if ((n = recv(fd, buf, sizeof(buf) - 1, 0)) < 0) { 351 fatal("recv"); 352 } else if (n == 0) { 353 maybe_syslog(LOG_NOTICE, "recv: EOF"); 354 iderror(fd, 0, 0, "UNKNOWN-ERROR"); 355 return 1; 356 } 357 buf[n] = '\0'; 358 359 /* Get local and remote ports from the received data. */ 360 p = buf; 361 while (*p != '\0' && isspace((unsigned char)*p)) 362 p++; 363 if ((p = strtok(p, " \t,")) != NULL) { 364 lport = atoi(p); 365 if ((p = strtok(NULL, " \t,")) != NULL) 366 fport = atoi(p); 367 } 368 369 /* Are the ports valid? */ 370 if (lport < 1 || lport > 65535 || fport < 1 || fport > 65535) { 371 maybe_syslog(LOG_NOTICE, "Invalid port(s): %d, %d from %s", 372 lport, fport, gethost((struct sockaddr *)&ss[0])); 373 iderror(fd, 0, 0, eflag ? "UNKNOWN-ERROR" : "INVALID-PORT"); 374 return 1; 375 } 376 377 /* If there is a 'lie' user enabled, then handle it now and stop. */ 378 if (Lflag) { 379 maybe_syslog(LOG_NOTICE, "Lying with name %s to %s", 380 idbuf, gethost((struct sockaddr *)&ss[0])); 381 idparse(fd, lport, fport, charset, osname, idbuf); 382 return 0; 383 } 384 385 /* Protocol dependent stuff. */ 386 switch (ss[0].ss_family) { 387 case AF_INET: 388 satosin(&ss[0])->sin_port = htons(fport); 389 satosin(&ss[1])->sin_port = htons(lport); 390 break; 391 case AF_INET6: 392 satosin6(&ss[0])->sin6_port = htons(fport); 393 satosin6(&ss[1])->sin6_port = htons(lport); 394 break; 395 default: 396 maybe_syslog(LOG_ERR, "Unsupported protocol (no. %d)", 397 ss[0].ss_family); 398 return 1; 399 } 400 401 /* Try to get the UID of the connection owner using sysctl. */ 402 if (ident_getuid(ss, sizeof(ss), proxy, &uid) == -1) { 403 /* Lookup failed, try to forward if enabled. */ 404 if (nat_lookup != NULL) { 405 struct sockaddr nat_addr; 406 int nat_lport; 407 408 (void)memset(&nat_addr, 0, sizeof(nat_addr)); 409 410 if ((*nat_lookup)(ss, &nat_addr, &nat_lport) && 411 forward(fd, &nat_addr, nat_lport, fport, lport)) { 412 maybe_syslog(LOG_INFO, 413 "Succesfully forwarded the request to %s", 414 gethost(&nat_addr)); 415 return 0; 416 } 417 } 418 /* Fall back to a default name? */ 419 if (fflag) { 420 maybe_syslog(LOG_NOTICE, "Using fallback name %s to %s", 421 idbuf, gethost((struct sockaddr *)&ss[0])); 422 idparse(fd, lport, fport, charset, osname, idbuf); 423 return 0; 424 } 425 maybe_syslog(LOG_ERR, "Lookup failed, returning error to %s", 426 gethost((struct sockaddr *)&ss[0])); 427 iderror(fd, lport, fport, eflag ? "UNKNOWN-ERROR" : "NO-USER"); 428 return 1; 429 } 430 431 /* Fill in userbuf with user name if possible, else numeric UID. */ 432 if ((pw = getpwuid(uid)) == NULL) { 433 maybe_syslog(LOG_ERR, "Couldn't map uid (%u) to name", uid); 434 (void)snprintf(userbuf, sizeof(userbuf), "%u", uid); 435 } else { 436 maybe_syslog(LOG_INFO, "Successful lookup: %d, %d: %s for %s", 437 lport, fport, pw->pw_name, 438 gethost((struct sockaddr *)&ss[0])); 439 (void)strlcpy(userbuf, pw->pw_name, sizeof(userbuf)); 440 } 441 442 /* No ident enabled? */ 443 if (Nflag && pw && check_noident(pw->pw_dir)) { 444 maybe_syslog(LOG_NOTICE, "Returning HIDDEN-USER for user %s" 445 " to %s", pw->pw_name, gethost((struct sockaddr *)&ss[0])); 446 iderror(fd, lport, fport, "HIDDEN-USER"); 447 return 1; 448 } 449 450 /* User ident enabled? */ 451 if (iflag && pw && check_userident(pw->pw_dir, idbuf, sizeof(idbuf))) { 452 if (!Iflag) { 453 if ((strspn(idbuf, "0123456789") && 454 getpwuid(atoi(idbuf)) != NULL) || 455 (getpwnam(idbuf) != NULL)) { 456 maybe_syslog(LOG_NOTICE, 457 "Ignoring user-specified '%s' for user %s", 458 idbuf, userbuf); 459 (void)strlcpy(idbuf, userbuf, sizeof(idbuf)); 460 } 461 } 462 maybe_syslog(LOG_NOTICE, 463 "Returning user-specified '%s' for user %s to %s", 464 idbuf, userbuf, gethost((struct sockaddr *)&ss[0])); 465 idparse(fd, lport, fport, charset, osname, idbuf); 466 return 0; 467 } 468 469 /* Send a random message? */ 470 if (rflag) { 471 /* Random number or string? */ 472 if (nflag) 473 (void)snprintf(idbuf, sizeof(idbuf), "%u", 474 (unsigned int)(arc4random() % 65535)); 475 else 476 random_string(idbuf, sizeof(idbuf)); 477 478 maybe_syslog(LOG_NOTICE, 479 "Returning random '%s' for user %s to %s", 480 idbuf, userbuf, gethost((struct sockaddr *)&ss[0])); 481 idparse(fd, lport, fport, charset, osname, idbuf); 482 return 0; 483 } 484 485 /* Return numberic user ID? */ 486 if (nflag) 487 (void)snprintf(idbuf, sizeof(idbuf), "%u", uid); 488 else 489 (void)strlcpy(idbuf, userbuf, sizeof(idbuf)); 490 491 /* 492 * Change the output format? Note that 512 is the maximum 493 * size of the result according to RFC 1413. 494 */ 495 if (Fflag && change_format(fmt, pw, buf, 512)) 496 idparse(fd, lport, fport, charset, osname, buf); 497 else 498 idparse(fd, lport, fport, charset, osname, idbuf); 499 500 return 0; 501 } 502 503 /* Send/parse the ident result. */ 504 static void 505 idparse(int fd, int lport, int fport, const char *charset, const char *osname, 506 const char *user) 507 { 508 char *p; 509 510 if (asprintf(&p, "%d,%d:USERID:%s%s%s:%s\r\n", lport, fport, 511 osname, charset ? "," : "", charset ? charset : "", user) < 0) 512 fatal("asprintf"); 513 if (send(fd, p, strlen(p), 0) < 0) { 514 free(p); 515 fatal("send"); 516 } 517 free(p); 518 } 519 520 /* Return a specified ident error. */ 521 static void 522 iderror(int fd, int lport, int fport, const char *error) 523 { 524 char *p; 525 526 if (asprintf(&p, "%d,%d:ERROR:%s\r\n", lport, fport, error) < 0) 527 fatal("asprintf"); 528 if (send(fd, p, strlen(p), 0) < 0) { 529 free(p); 530 fatal("send"); 531 } 532 free(p); 533 } 534 535 /* Return the IP address of the connecting host. */ 536 static const char * 537 gethost(struct sockaddr *sa) 538 { 539 static char host[NI_MAXHOST]; 540 541 if (getnameinfo(sa, sa->sa_len, host, sizeof(host), 542 NULL, 0, NI_NUMERICHOST) == 0) 543 return host; 544 545 return "UNKNOWN"; 546 } 547 548 /* Setup sockets, for daemon mode. */ 549 static int * 550 socketsetup(const char *address, const char *port, int af) 551 { 552 struct addrinfo hints, *res, *res0; 553 int error, maxs, *s, *socks, y = 1; 554 const char *cause = NULL; 555 556 (void)memset(&hints, 0, sizeof(hints)); 557 hints.ai_flags = AI_PASSIVE; 558 hints.ai_family = af; 559 hints.ai_socktype = SOCK_STREAM; 560 error = getaddrinfo(address, port, &hints, &res0); 561 if (error) { 562 die("getaddrinfo: %s", gai_strerror(error)); 563 /* NOTREACHED */ 564 } 565 566 /* Count max number of sockets we may open. */ 567 for (maxs = 0, res = res0; res != NULL; res = res->ai_next) 568 maxs++; 569 570 socks = malloc((maxs + 1) * sizeof(int)); 571 if (socks == NULL) { 572 die("malloc: %s", strerror(errno)); 573 /* NOTREACHED */ 574 } 575 576 *socks = 0; 577 s = socks + 1; 578 for (res = res0; res != NULL; res = res->ai_next) { 579 *s = socket(res->ai_family, res->ai_socktype, res->ai_protocol); 580 if (*s < 0) { 581 cause = "socket"; 582 continue; 583 } 584 (void)setsockopt(*s, SOL_SOCKET, SO_REUSEADDR, &y, sizeof(y)); 585 if (bind(*s, res->ai_addr, res->ai_addrlen) < 0) { 586 cause = "bind"; 587 (void)close(*s); 588 continue; 589 } 590 if (listen(*s, 5) < 0) { 591 cause = "listen"; 592 (void)close(*s); 593 continue; 594 } 595 *socks = *socks + 1; 596 s++; 597 } 598 599 if (*socks == 0) { 600 free(socks); 601 die("%s: %s", cause, strerror(errno)); 602 /* NOTREACHED */ 603 } 604 if (res0) 605 freeaddrinfo(res0); 606 607 return socks; 608 } 609 610 /* UID lookup wrapper. */ 611 static int 612 ident_getuid(struct sockaddr_storage *ss, socklen_t len, 613 struct sockaddr *proxy, uid_t *uid) 614 { 615 int rc; 616 617 rc = sysctl_getuid(ss, len, uid); 618 if (rc == -1 && proxy != NULL) 619 rc = sysctl_proxy_getuid(ss, proxy, uid); 620 621 return rc; 622 } 623 624 /* Try to get the UID of the connection owner using sysctl. */ 625 static int 626 sysctl_getuid(struct sockaddr_storage *ss, socklen_t len, uid_t *uid) 627 { 628 int mib[4]; 629 uid_t myuid; 630 size_t uidlen; 631 632 uidlen = sizeof(myuid); 633 634 mib[0] = CTL_NET; 635 mib[1] = ss->ss_family; 636 mib[2] = IPPROTO_TCP; 637 mib[3] = TCPCTL_IDENT; 638 639 if (sysctl(mib, sizeof(mib)/ sizeof(int), &myuid, &uidlen, ss, len) < 0) 640 return -1; 641 *uid = myuid; 642 643 return 0; 644 } 645 646 /* Try to get the UID of the connection owner using sysctl (proxy version). */ 647 static int 648 sysctl_proxy_getuid(struct sockaddr_storage *ss, struct sockaddr *proxy, 649 uid_t *uid) 650 { 651 struct sockaddr_storage new[2]; 652 int i, rc, name[CTL_MAXNAME]; 653 struct kinfo_pcb *kp; 654 size_t sz, len; 655 const char *list; 656 657 rc = -1; 658 sz = CTL_MAXNAME; 659 list = NULL; 660 661 /* Retrieve a list of sockets. */ 662 switch (ss[0].ss_family) { 663 case AF_INET: 664 /* We only accept queries from the proxy. */ 665 if (in_hosteq(satosin(&ss[0])->sin_addr, 666 satosin(proxy)->sin_addr)) 667 list = "net.inet.tcp.pcblist"; 668 break; 669 case AF_INET6: 670 /* We only accept queries from the proxy. */ 671 if (IN6_ARE_ADDR_EQUAL(&satosin6(&ss[0])->sin6_addr, 672 &satosin6(proxy)->sin6_addr)) 673 list = "net.inet6.tcp.pcblist"; 674 break; 675 default: 676 maybe_syslog(LOG_ERR, "Unsupported protocol for proxy (no. %d)", 677 ss[0].ss_family); 678 } 679 if (list != NULL) 680 rc = sysctlnametomib(list, &name[0], &sz); 681 if (rc == -1) 682 return -1; 683 len = sz; 684 685 name[len++] = PCB_ALL; 686 name[len++] = 0; 687 name[len++] = sizeof(struct kinfo_pcb); 688 name[len++] = INT_MAX; 689 690 kp = NULL; 691 sz = 0; 692 do { 693 rc = sysctl(&name[0], len, kp, &sz, NULL, 0); 694 if (rc == -1 && errno != ENOMEM) 695 return -1; 696 if (kp == NULL) { 697 kp = malloc(sz); 698 rc = -1; 699 } 700 if (kp == NULL) 701 return -1; 702 } while (rc == -1); 703 704 rc = -1; 705 /* 706 * Walk through the list of sockets and try to find a match. 707 * We don't know who has sent the query (we only know that the 708 * proxy has forwarded to us) so just try to match the ports and 709 * the local address. 710 */ 711 for (i = 0; i < sz / sizeof(struct kinfo_pcb); i++) { 712 switch (ss[0].ss_family) { 713 case AF_INET: 714 /* Foreign and local ports must match. */ 715 if (satosin(&ss[0])->sin_port != 716 satosin(&kp[i].ki_src)->sin_port) 717 continue; 718 if (satosin(&ss[1])->sin_port != 719 satosin(&kp[i].ki_dst)->sin_port) 720 continue; 721 /* Foreign address may not match proxy address. */ 722 if (in_hosteq(satosin(proxy)->sin_addr, 723 satosin(&kp[i].ki_dst)->sin_addr)) 724 continue; 725 /* Local addresses must match. */ 726 if (!in_hosteq(satosin(&ss[1])->sin_addr, 727 satosin(&kp[i].ki_src)->sin_addr)) 728 continue; 729 break; 730 case AF_INET6: 731 /* Foreign and local ports must match. */ 732 if (satosin6(&ss[0])->sin6_port != 733 satosin6(&kp[i].ki_src)->sin6_port) 734 continue; 735 if (satosin6(&ss[1])->sin6_port != 736 satosin6(&kp[i].ki_dst)->sin6_port) 737 continue; 738 /* Foreign address may not match proxy address. */ 739 if (IN6_ARE_ADDR_EQUAL(&satosin6(proxy)->sin6_addr, 740 &satosin6(&kp[i].ki_dst)->sin6_addr)) 741 continue; 742 /* Local addresses must match. */ 743 if (!IN6_ARE_ADDR_EQUAL(&satosin6(&ss[1])->sin6_addr, 744 &satosin6(&kp[i].ki_src)->sin6_addr)) 745 continue; 746 break; 747 } 748 749 /* 750 * We have found the foreign address, copy it to a new 751 * struct and retrieve the UID of the connection owner. 752 */ 753 (void)memcpy(&new[0], &kp[i].ki_dst, kp[i].ki_dst.sa_len); 754 (void)memcpy(&new[1], &kp[i].ki_src, kp[i].ki_src.sa_len); 755 756 rc = sysctl_getuid(new, sizeof(new), uid); 757 758 /* Done. */ 759 break; 760 } 761 762 free(kp); 763 return rc; 764 } 765 766 /* Forward ident queries. Returns 1 when succesful, or zero if not. */ 767 static int 768 forward(int fd, struct sockaddr *nat_addr, int nat_lport, int fport, int lport) 769 { 770 char buf[BUFSIZ], reply[BUFSIZ], *p; 771 int sock, n; 772 773 /* Connect to the NAT host. */ 774 sock = socket(nat_addr->sa_family, SOCK_STREAM, 0); 775 if (sock < 0) { 776 maybe_syslog(LOG_ERR, "socket: %m"); 777 return 0; 778 } 779 if (connect(sock, nat_addr, nat_addr->sa_len) < 0) { 780 maybe_syslog(LOG_ERR, "Can't connect to %s: %m", 781 gethost(nat_addr)); 782 (void)close(sock); 783 return 0; 784 } 785 786 /* 787 * Send the ident query to the NAT host, but use as local port 788 * the port of the NAT host. 789 */ 790 (void)snprintf(buf, sizeof(buf), "%d , %d\r\n", nat_lport, fport); 791 if (send(sock, buf, strlen(buf), 0) < 0) { 792 maybe_syslog(LOG_ERR, "send: %m"); 793 (void)close(sock); 794 return 0; 795 } 796 797 /* Read the reply from the NAT host. */ 798 if ((n = recv(sock, reply, sizeof(reply) - 1, 0)) < 0) { 799 maybe_syslog(LOG_ERR, "recv: %m"); 800 (void)close(sock); 801 return 0; 802 } else if (n == 0) { 803 maybe_syslog(LOG_NOTICE, "recv: EOF"); 804 (void)close(sock); 805 return 0; 806 } 807 reply[n] = '\0'; 808 (void)close(sock); 809 810 /* Extract everything after the port specs from the ident reply. */ 811 for (p = reply; *p != '\0' && *p != ':'; p++) 812 continue; 813 if (*p == '\0' || *++p == '\0') { 814 maybe_syslog(LOG_ERR, "Malformed ident reply from %s", 815 gethost(nat_addr)); 816 return 0; 817 } 818 /* Build reply for the requesting host, use the original local port. */ 819 (void)snprintf(buf, sizeof(buf), "%d,%d:%s", lport, fport, p); 820 821 /* Send the reply from the NAT host back to the requesting host. */ 822 if (send(fd, buf, strlen(buf), 0) < 0) { 823 maybe_syslog(LOG_ERR, "send: %m"); 824 return 0; 825 } 826 827 return 1; 828 } 829 830 /* Check if a .noident file exists in the user home directory. */ 831 static int 832 check_noident(const char *homedir) 833 { 834 struct stat sb; 835 char *path; 836 int ret; 837 838 if (homedir == NULL) 839 return 0; 840 if (asprintf(&path, "%s/.noident", homedir) < 0) 841 return 0; 842 ret = stat(path, &sb); 843 844 free(path); 845 return (ret == 0); 846 } 847 848 /* 849 * Check if a .ident file exists in the user home directory and 850 * return the contents of that file. 851 */ 852 static int 853 check_userident(const char *homedir, char *username, size_t len) 854 { 855 struct stat sb; 856 char *path, *p; 857 int fd, n; 858 859 if (len == 0 || homedir == NULL) 860 return 0; 861 if (asprintf(&path, "%s/.ident", homedir) < 0) 862 return 0; 863 if ((fd = open(path, O_RDONLY|O_NONBLOCK|O_NOFOLLOW, 0)) < 0) { 864 free(path); 865 return 0; 866 } 867 if (fstat(fd, &sb) < 0 || !S_ISREG(sb.st_mode)) { 868 (void)close(fd); 869 free(path); 870 return 0; 871 } 872 if ((n = read(fd, username, len - 1)) < 1) { 873 (void)close(fd); 874 free(path); 875 return 0; 876 } 877 username[n] = '\0'; 878 879 if ((p = strpbrk(username, "\r\n")) != NULL) 880 *p = '\0'; 881 882 (void)close(fd); 883 free(path); 884 return 1; 885 } 886 887 /* Generate a random string. */ 888 static void 889 random_string(char *str, size_t len) 890 { 891 static const char chars[] = "abcdefghijklmnopqrstuvwxyz1234567890"; 892 char *p; 893 894 if (len == 0) 895 return; 896 for (p = str; len > 1; len--) 897 *p++ = chars[arc4random() % (sizeof(chars) - 1)]; 898 *p = '\0'; 899 } 900 901 /* Change the output format. */ 902 static int 903 change_format(const char *format, struct passwd *pw, char *dest, size_t len) 904 { 905 struct group *gr; 906 const char *cp; 907 char **gmp; 908 int bp; 909 910 if (len == 0 || ((gr = getgrgid(pw->pw_gid)) == NULL)) 911 return 0; 912 913 for (bp = 0, cp = format; *cp != '\0' && bp < 490; cp++) { 914 if (*cp != '%') { 915 dest[bp++] = *cp; 916 continue; 917 } 918 if (*++cp == '\0') 919 break; 920 switch (*cp) { 921 case 'u': 922 (void)snprintf(&dest[bp], len - bp, "%.*s", 490 - bp, 923 pw->pw_name); 924 break; 925 case 'U': 926 (void)snprintf(&dest[bp], len - bp, "%d", pw->pw_uid); 927 break; 928 case 'g': 929 (void)snprintf(&dest[bp], len - bp, "%.*s", 490 - bp, 930 gr->gr_name); 931 break; 932 case 'G': 933 (void)snprintf(&dest[bp], len - bp, "%d", gr->gr_gid); 934 break; 935 case 'l': 936 (void)snprintf(&dest[bp], len - bp, "%.*s", 490 - bp, 937 gr->gr_name); 938 bp += strlen(&dest[bp]); 939 if (bp >= 490) 940 break; 941 setgrent(); 942 while ((gr = getgrent()) != NULL) { 943 if (gr->gr_gid == pw->pw_gid) 944 continue; 945 for (gmp = gr->gr_mem; *gmp && **gmp; gmp++) { 946 if (strcmp(*gmp, pw->pw_name) == 0) { 947 (void)snprintf(&dest[bp], 948 len - bp, ",%.*s", 949 490 - bp, gr->gr_name); 950 bp += strlen(&dest[bp]); 951 break; 952 } 953 } 954 if (bp >= 490) 955 break; 956 } 957 endgrent(); 958 break; 959 case 'L': 960 (void)snprintf(&dest[bp], len - bp, "%u", gr->gr_gid); 961 bp += strlen(&dest[bp]); 962 if (bp >= 490) 963 break; 964 setgrent(); 965 while ((gr = getgrent()) != NULL) { 966 if (gr->gr_gid == pw->pw_gid) 967 continue; 968 for (gmp = gr->gr_mem; *gmp && **gmp; gmp++) { 969 if (strcmp(*gmp, pw->pw_name) == 0) { 970 (void)snprintf(&dest[bp], 971 len - bp, ",%u", 972 gr->gr_gid); 973 bp += strlen(&dest[bp]); 974 break; 975 } 976 } 977 if (bp >= 490) 978 break; 979 } 980 endgrent(); 981 break; 982 default: 983 dest[bp] = *cp; 984 dest[bp+1] = '\0'; 985 break; 986 } 987 bp += strlen(&dest[bp]); 988 } 989 if (bp >= 490) { 990 (void)snprintf(&dest[490], len - 490, "..."); 991 bp = 493; 992 } 993 dest[bp] = '\0'; 994 995 return 1; 996 } 997 998 /* Just exit when we caught SIGALRM. */ 999 static void 1000 timeout_handler(int s) 1001 { 1002 maybe_syslog(LOG_DEBUG, "SIGALRM triggered, exiting..."); 1003 exit(EXIT_FAILURE); 1004 } 1005 1006 /* Report error message string through syslog and quit. */ 1007 static void 1008 fatal(const char *func) 1009 { 1010 maybe_syslog(LOG_ERR, "%s: %m", func); 1011 exit(EXIT_FAILURE); 1012 } 1013 1014 /* 1015 * Report an error through syslog and/or stderr and quit. Only used when 1016 * running identd in the background and when it isn't a daemon yet. 1017 */ 1018 static void 1019 die(const char *message, ...) 1020 { 1021 va_list ap; 1022 1023 va_start(ap, message); 1024 if (bflag) 1025 vwarnx(message, ap); 1026 if (lflag) 1027 vsyslog(LOG_ERR, message, ap); 1028 va_end(ap); 1029 1030 exit(EXIT_FAILURE); 1031 } 1032 1033 /* Log using syslog, but only if enabled with the -l flag. */ 1034 void 1035 maybe_syslog(int priority, const char *message, ...) 1036 { 1037 va_list ap; 1038 1039 if (lflag) { 1040 va_start(ap, message); 1041 vsyslog(priority, message, ap); 1042 va_end(ap); 1043 } 1044 } 1045
Indexes created Tue Sep 23 02:09:52 GMT 2025