identd.c revision 1.29
1 /* $NetBSD: identd.c,v 1.29 2005/06/14 12:17:13 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/cdefs.h> 11 __RCSID("$NetBSD: identd.c,v 1.29 2005/06/14 12:17:13 peter Exp $"); 12 13 #include <sys/param.h> 14 #include <sys/socket.h> 15 #include <sys/stat.h> 16 #include <sys/sysctl.h> 17 18 #include <netinet/in.h> 19 #include <netinet/ip_var.h> 20 #include <netinet/tcp.h> 21 #include <netinet/tcp_timer.h> 22 #include <netinet/tcp_var.h> 23 24 #include <arpa/inet.h> 25 26 #include <ctype.h> 27 #include <err.h> 28 #include <errno.h> 29 #include <fcntl.h> 30 #include <grp.h> 31 #include <netdb.h> 32 #include <poll.h> 33 #include <pwd.h> 34 #include <signal.h> 35 #include <stdarg.h> 36 #include <stdio.h> 37 #include <stdlib.h> 38 #include <string.h> 39 #include <syslog.h> 40 #include <unistd.h> 41 42 #include "identd.h" 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, 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 socks = NULL; 103 IPv4or6 = AF_UNSPEC; 104 osname = OPSYS_NAME; 105 portno = IDENT_SERVICE; 106 timeout = TIMEOUT; 107 nat_lookup = NULL; 108 proxy_addr = NULL; 109 filter = proxy = NULL; 110 address = charset = fmt = NULL; 111 uid = gid = 0; 112 bflag = eflag = fflag = iflag = Iflag = 0; 113 lflag = Lflag = nflag = Nflag = rflag = 0; 114 115 /* Started from a tty? then run as daemon. */ 116 if (isatty(STDIN_FILENO)) 117 bflag = 1; 118 119 /* Parse command line arguments. */ 120 while ((ch = getopt(argc, argv, 121 "46a:bceF:f:g:IiL:lm:Nno:P:p:rt:u:")) != -1) { 122 switch (ch) { 123 case '4': 124 IPv4or6 = AF_INET; 125 break; 126 case '6': 127 IPv4or6 = AF_INET6; 128 break; 129 case 'a': 130 address = optarg; 131 break; 132 case 'b': 133 bflag = 1; 134 break; 135 case 'c': 136 charset = optarg; 137 break; 138 case 'e': 139 eflag = 1; 140 break; 141 case 'F': 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 /* 312 * Handle a request on the ident port. Returns 0 on success or 1 on 313 * failure. The return values are currently ignored. 314 */ 315 static int 316 idhandle(int fd, const char *charset, const char *fmt, const char *osname, 317 const char *user, struct sockaddr *proxy, int timeout) 318 { 319 struct sockaddr_storage ss[2]; 320 char userbuf[LOGIN_NAME_MAX]; /* actual user name (or numeric uid) */ 321 char idbuf[LOGIN_NAME_MAX]; /* name to be used in response */ 322 char buf[BUFSIZ], *p; 323 struct passwd *pw; 324 int lport, fport; 325 socklen_t len; 326 uid_t uid; 327 ssize_t n; 328 329 lport = fport = 0; 330 331 (void)strlcpy(idbuf, user, sizeof(idbuf)); 332 (void)signal(SIGALRM, timeout_handler); 333 (void)alarm(timeout); 334 335 /* Get foreign internet address. */ 336 len = sizeof(ss[0]); 337 if (getpeername(fd, (struct sockaddr *)&ss[0], &len) < 0) 338 fatal("getpeername"); 339 340 maybe_syslog(LOG_INFO, "Connection from %s", 341 gethost((struct sockaddr *)&ss[0])); 342 343 /* Get local internet address. */ 344 len = sizeof(ss[1]); 345 if (getsockname(fd, (struct sockaddr *)&ss[1], &len) < 0) 346 fatal("getsockname"); 347 348 /* Be sure to have the same address families. */ 349 if (ss[0].ss_family != ss[1].ss_family) { 350 maybe_syslog(LOG_ERR, "Different foreign/local address family"); 351 return 1; 352 } 353 354 /* Receive data from the client. */ 355 if ((n = recv(fd, buf, sizeof(buf) - 1, 0)) < 0) { 356 fatal("recv"); 357 } else if (n == 0) { 358 maybe_syslog(LOG_NOTICE, "recv: EOF"); 359 iderror(fd, 0, 0, "UNKNOWN-ERROR"); 360 return 1; 361 } 362 buf[n] = '\0'; 363 364 /* Get local and remote ports from the received data. */ 365 p = buf; 366 while (*p != '\0' && isspace((unsigned char)*p)) 367 p++; 368 if ((p = strtok(p, " \t,")) != NULL) { 369 lport = atoi(p); 370 if ((p = strtok(NULL, " \t,")) != NULL) 371 fport = atoi(p); 372 } 373 374 /* Are the ports valid? */ 375 if (lport < 1 || lport > 65535 || fport < 1 || fport > 65535) { 376 maybe_syslog(LOG_NOTICE, "Invalid port(s): %d, %d from %s", 377 lport, fport, gethost((struct sockaddr *)&ss[0])); 378 iderror(fd, 0, 0, eflag ? "UNKNOWN-ERROR" : "INVALID-PORT"); 379 return 1; 380 } 381 382 /* If there is a 'lie' user enabled, then handle it now and stop. */ 383 if (Lflag) { 384 maybe_syslog(LOG_NOTICE, "Lying with name %s to %s", 385 idbuf, gethost((struct sockaddr *)&ss[0])); 386 idparse(fd, lport, fport, charset, osname, idbuf); 387 return 0; 388 } 389 390 /* Protocol dependent stuff. */ 391 switch (ss[0].ss_family) { 392 case AF_INET: 393 satosin(&ss[0])->sin_port = htons(fport); 394 satosin(&ss[1])->sin_port = htons(lport); 395 break; 396 case AF_INET6: 397 satosin6(&ss[0])->sin6_port = htons(fport); 398 satosin6(&ss[1])->sin6_port = htons(lport); 399 break; 400 default: 401 maybe_syslog(LOG_ERR, "Unsupported protocol (no. %d)", 402 ss[0].ss_family); 403 return 1; 404 } 405 406 /* Try to get the UID of the connection owner using sysctl. */ 407 if (ident_getuid(ss, sizeof(ss), proxy, &uid) == -1) { 408 /* Lookup failed, try to forward if enabled. */ 409 if (nat_lookup != NULL) { 410 struct sockaddr nat_addr; 411 int nat_lport; 412 413 (void)memset(&nat_addr, 0, sizeof(nat_addr)); 414 415 if ((*nat_lookup)(ss, &nat_addr, &nat_lport) && 416 forward(fd, &nat_addr, nat_lport, fport, lport)) { 417 maybe_syslog(LOG_INFO, 418 "Succesfully forwarded the request to %s", 419 gethost(&nat_addr)); 420 return 0; 421 } 422 } 423 /* Fall back to a default name? */ 424 if (fflag) { 425 maybe_syslog(LOG_NOTICE, "Using fallback name %s to %s", 426 idbuf, gethost((struct sockaddr *)&ss[0])); 427 idparse(fd, lport, fport, charset, osname, idbuf); 428 return 0; 429 } 430 maybe_syslog(LOG_ERR, "Lookup failed, returning error to %s", 431 gethost((struct sockaddr *)&ss[0])); 432 iderror(fd, lport, fport, eflag ? "UNKNOWN-ERROR" : "NO-USER"); 433 return 1; 434 } 435 436 /* Fill in userbuf with user name if possible, else numeric UID. */ 437 if ((pw = getpwuid(uid)) == NULL) { 438 maybe_syslog(LOG_ERR, "Couldn't map uid (%u) to name", uid); 439 (void)snprintf(userbuf, sizeof(userbuf), "%u", uid); 440 } else { 441 maybe_syslog(LOG_INFO, "Successful lookup: %d, %d: %s for %s", 442 lport, fport, pw->pw_name, 443 gethost((struct sockaddr *)&ss[0])); 444 (void)strlcpy(userbuf, pw->pw_name, sizeof(userbuf)); 445 } 446 447 /* No ident enabled? */ 448 if (Nflag && pw && check_noident(pw->pw_dir)) { 449 maybe_syslog(LOG_NOTICE, "Returning HIDDEN-USER for user %s" 450 " to %s", pw->pw_name, gethost((struct sockaddr *)&ss[0])); 451 iderror(fd, lport, fport, "HIDDEN-USER"); 452 return 1; 453 } 454 455 /* User ident enabled? */ 456 if (iflag && pw && check_userident(pw->pw_dir, idbuf, sizeof(idbuf))) { 457 if (!Iflag) { 458 if ((strspn(idbuf, "0123456789") && 459 getpwuid(atoi(idbuf)) != NULL) || 460 (getpwnam(idbuf) != NULL)) { 461 maybe_syslog(LOG_NOTICE, 462 "Ignoring user-specified '%s' for user %s", 463 idbuf, userbuf); 464 (void)strlcpy(idbuf, userbuf, sizeof(idbuf)); 465 } 466 } 467 maybe_syslog(LOG_NOTICE, 468 "Returning user-specified '%s' for user %s to %s", 469 idbuf, userbuf, gethost((struct sockaddr *)&ss[0])); 470 idparse(fd, lport, fport, charset, osname, idbuf); 471 return 0; 472 } 473 474 /* Send a random message? */ 475 if (rflag) { 476 /* Random number or string? */ 477 if (nflag) 478 (void)snprintf(idbuf, sizeof(idbuf), "%u", 479 (unsigned int)(arc4random() % 65535)); 480 else 481 random_string(idbuf, sizeof(idbuf)); 482 483 maybe_syslog(LOG_NOTICE, 484 "Returning random '%s' for user %s to %s", 485 idbuf, userbuf, gethost((struct sockaddr *)&ss[0])); 486 idparse(fd, lport, fport, charset, osname, idbuf); 487 return 0; 488 } 489 490 /* Return numberic user ID? */ 491 if (nflag) 492 (void)snprintf(idbuf, sizeof(idbuf), "%u", uid); 493 else 494 (void)strlcpy(idbuf, userbuf, sizeof(idbuf)); 495 496 /* 497 * Change the output format? Note that 512 is the maximum 498 * size of the result according to RFC 1413. 499 */ 500 if (fmt && change_format(fmt, pw, buf, 512 + 1)) 501 idparse(fd, lport, fport, charset, osname, buf); 502 else 503 idparse(fd, lport, fport, charset, osname, idbuf); 504 505 return 0; 506 } 507 508 /* Send/parse the ident result. */ 509 static void 510 idparse(int fd, int lport, int fport, const char *charset, const char *osname, 511 const char *user) 512 { 513 char *p; 514 515 if (asprintf(&p, "%d,%d:USERID:%s%s%s:%s\r\n", lport, fport, 516 osname, charset ? "," : "", charset ? charset : "", user) < 0) 517 fatal("asprintf"); 518 if (send(fd, p, strlen(p), 0) < 0) { 519 free(p); 520 fatal("send"); 521 } 522 free(p); 523 } 524 525 /* Return a specified ident error. */ 526 static void 527 iderror(int fd, int lport, int fport, const char *error) 528 { 529 char *p; 530 531 if (asprintf(&p, "%d,%d:ERROR:%s\r\n", lport, fport, error) < 0) 532 fatal("asprintf"); 533 if (send(fd, p, strlen(p), 0) < 0) { 534 free(p); 535 fatal("send"); 536 } 537 free(p); 538 } 539 540 /* Return the IP address of the connecting host. */ 541 static const char * 542 gethost(struct sockaddr *sa) 543 { 544 static char host[NI_MAXHOST]; 545 546 if (getnameinfo(sa, sa->sa_len, host, sizeof(host), 547 NULL, 0, NI_NUMERICHOST) == 0) 548 return host; 549 550 return "UNKNOWN"; 551 } 552 553 /* Setup sockets, for daemon mode. */ 554 static int * 555 socketsetup(const char *address, const char *port, int af) 556 { 557 struct addrinfo hints, *res, *res0; 558 int error, maxs, *s, *socks; 559 const char *cause = NULL; 560 socklen_t y = 1; 561 562 (void)memset(&hints, 0, sizeof(hints)); 563 hints.ai_flags = AI_PASSIVE; 564 hints.ai_family = af; 565 hints.ai_socktype = SOCK_STREAM; 566 error = getaddrinfo(address, port, &hints, &res0); 567 if (error) { 568 die("getaddrinfo: %s", gai_strerror(error)); 569 /* NOTREACHED */ 570 } 571 572 /* Count max number of sockets we may open. */ 573 for (maxs = 0, res = res0; res != NULL; res = res->ai_next) 574 maxs++; 575 576 socks = malloc((maxs + 1) * sizeof(int)); 577 if (socks == NULL) { 578 die("malloc: %s", strerror(errno)); 579 /* NOTREACHED */ 580 } 581 582 *socks = 0; 583 s = socks + 1; 584 for (res = res0; res != NULL; res = res->ai_next) { 585 *s = socket(res->ai_family, res->ai_socktype, res->ai_protocol); 586 if (*s < 0) { 587 cause = "socket"; 588 continue; 589 } 590 (void)setsockopt(*s, SOL_SOCKET, SO_REUSEADDR, &y, sizeof(y)); 591 if (bind(*s, res->ai_addr, res->ai_addrlen) < 0) { 592 cause = "bind"; 593 (void)close(*s); 594 continue; 595 } 596 if (listen(*s, 5) < 0) { 597 cause = "listen"; 598 (void)close(*s); 599 continue; 600 } 601 *socks = *socks + 1; 602 s++; 603 } 604 605 if (*socks == 0) { 606 free(socks); 607 die("%s: %s", cause, strerror(errno)); 608 /* NOTREACHED */ 609 } 610 if (res0) 611 freeaddrinfo(res0); 612 613 return socks; 614 } 615 616 /* UID lookup wrapper. */ 617 static int 618 ident_getuid(struct sockaddr_storage *ss, socklen_t len, 619 struct sockaddr *proxy, uid_t *uid) 620 { 621 int rc; 622 623 rc = sysctl_getuid(ss, len, uid); 624 if (rc == -1 && proxy != NULL) 625 rc = sysctl_proxy_getuid(ss, proxy, uid); 626 627 return rc; 628 } 629 630 /* Try to get the UID of the connection owner using sysctl. */ 631 static int 632 sysctl_getuid(struct sockaddr_storage *ss, socklen_t len, uid_t *uid) 633 { 634 int mib[4]; 635 uid_t myuid; 636 size_t uidlen; 637 638 uidlen = sizeof(myuid); 639 640 mib[0] = CTL_NET; 641 mib[1] = ss->ss_family; 642 mib[2] = IPPROTO_TCP; 643 mib[3] = TCPCTL_IDENT; 644 645 if (sysctl(mib, sizeof(mib)/ sizeof(int), &myuid, &uidlen, ss, len) < 0) 646 return -1; 647 *uid = myuid; 648 649 return 0; 650 } 651 652 /* Try to get the UID of the connection owner using sysctl (proxy version). */ 653 static int 654 sysctl_proxy_getuid(struct sockaddr_storage *ss, struct sockaddr *proxy, 655 uid_t *uid) 656 { 657 struct sockaddr_storage new[2]; 658 int i, rc, name[CTL_MAXNAME]; 659 struct kinfo_pcb *kp; 660 size_t sz, len; 661 const char *list; 662 663 rc = -1; 664 sz = CTL_MAXNAME; 665 list = NULL; 666 667 /* Retrieve a list of sockets. */ 668 switch (ss[0].ss_family) { 669 case AF_INET: 670 /* We only accept queries from the proxy. */ 671 if (in_hosteq(satosin(&ss[0])->sin_addr, 672 satosin(proxy)->sin_addr)) 673 list = "net.inet.tcp.pcblist"; 674 break; 675 case AF_INET6: 676 /* We only accept queries from the proxy. */ 677 if (IN6_ARE_ADDR_EQUAL(&satosin6(&ss[0])->sin6_addr, 678 &satosin6(proxy)->sin6_addr)) 679 list = "net.inet6.tcp.pcblist"; 680 break; 681 default: 682 maybe_syslog(LOG_ERR, "Unsupported protocol for proxy (no. %d)", 683 ss[0].ss_family); 684 } 685 if (list != NULL) 686 rc = sysctlnametomib(list, &name[0], &sz); 687 if (rc == -1) 688 return -1; 689 len = sz; 690 691 name[len++] = PCB_ALL; 692 name[len++] = 0; 693 name[len++] = sizeof(struct kinfo_pcb); 694 name[len++] = INT_MAX; 695 696 kp = NULL; 697 sz = 0; 698 do { 699 rc = sysctl(&name[0], len, kp, &sz, NULL, 0); 700 if (rc == -1 && errno != ENOMEM) 701 return -1; 702 if (kp == NULL) { 703 kp = malloc(sz); 704 rc = -1; 705 } 706 if (kp == NULL) 707 return -1; 708 } while (rc == -1); 709 710 rc = -1; 711 /* 712 * Walk through the list of sockets and try to find a match. 713 * We don't know who has sent the query (we only know that the 714 * proxy has forwarded to us) so just try to match the ports and 715 * the local address. 716 */ 717 for (i = 0; i < sz / sizeof(struct kinfo_pcb); i++) { 718 switch (ss[0].ss_family) { 719 case AF_INET: 720 /* Foreign and local ports must match. */ 721 if (satosin(&ss[0])->sin_port != 722 satosin(&kp[i].ki_src)->sin_port) 723 continue; 724 if (satosin(&ss[1])->sin_port != 725 satosin(&kp[i].ki_dst)->sin_port) 726 continue; 727 /* Foreign address may not match proxy address. */ 728 if (in_hosteq(satosin(proxy)->sin_addr, 729 satosin(&kp[i].ki_dst)->sin_addr)) 730 continue; 731 /* Local addresses must match. */ 732 if (!in_hosteq(satosin(&ss[1])->sin_addr, 733 satosin(&kp[i].ki_src)->sin_addr)) 734 continue; 735 break; 736 case AF_INET6: 737 /* Foreign and local ports must match. */ 738 if (satosin6(&ss[0])->sin6_port != 739 satosin6(&kp[i].ki_src)->sin6_port) 740 continue; 741 if (satosin6(&ss[1])->sin6_port != 742 satosin6(&kp[i].ki_dst)->sin6_port) 743 continue; 744 /* Foreign address may not match proxy address. */ 745 if (IN6_ARE_ADDR_EQUAL(&satosin6(proxy)->sin6_addr, 746 &satosin6(&kp[i].ki_dst)->sin6_addr)) 747 continue; 748 /* Local addresses must match. */ 749 if (!IN6_ARE_ADDR_EQUAL(&satosin6(&ss[1])->sin6_addr, 750 &satosin6(&kp[i].ki_src)->sin6_addr)) 751 continue; 752 break; 753 } 754 755 /* 756 * We have found the foreign address, copy it to a new 757 * struct and retrieve the UID of the connection owner. 758 */ 759 (void)memcpy(&new[0], &kp[i].ki_dst, kp[i].ki_dst.sa_len); 760 (void)memcpy(&new[1], &kp[i].ki_src, kp[i].ki_src.sa_len); 761 762 rc = sysctl_getuid(new, sizeof(new), uid); 763 764 /* Done. */ 765 break; 766 } 767 768 free(kp); 769 return rc; 770 } 771 772 /* Forward ident queries. Returns 1 when succesful, or zero if not. */ 773 static int 774 forward(int fd, struct sockaddr *nat_addr, int nat_lport, int fport, int lport) 775 { 776 char buf[BUFSIZ], reply[BUFSIZ], *p; 777 ssize_t n; 778 int sock; 779 780 /* Connect to the NAT host. */ 781 sock = socket(nat_addr->sa_family, SOCK_STREAM, 0); 782 if (sock < 0) { 783 maybe_syslog(LOG_ERR, "socket: %m"); 784 return 0; 785 } 786 if (connect(sock, nat_addr, nat_addr->sa_len) < 0) { 787 maybe_syslog(LOG_ERR, "Can't connect to %s: %m", 788 gethost(nat_addr)); 789 (void)close(sock); 790 return 0; 791 } 792 793 /* 794 * Send the ident query to the NAT host, but use as local port 795 * the port of the NAT host. 796 */ 797 (void)snprintf(buf, sizeof(buf), "%d , %d\r\n", nat_lport, fport); 798 if (send(sock, buf, strlen(buf), 0) < 0) { 799 maybe_syslog(LOG_ERR, "send: %m"); 800 (void)close(sock); 801 return 0; 802 } 803 804 /* Read the reply from the NAT host. */ 805 if ((n = recv(sock, reply, sizeof(reply) - 1, 0)) < 0) { 806 maybe_syslog(LOG_ERR, "recv: %m"); 807 (void)close(sock); 808 return 0; 809 } else if (n == 0) { 810 maybe_syslog(LOG_NOTICE, "recv: EOF"); 811 (void)close(sock); 812 return 0; 813 } 814 reply[n] = '\0'; 815 (void)close(sock); 816 817 /* Extract everything after the port specs from the ident reply. */ 818 for (p = reply; *p != '\0' && *p != ':'; p++) 819 continue; 820 if (*p == '\0' || *++p == '\0') { 821 maybe_syslog(LOG_ERR, "Malformed ident reply from %s", 822 gethost(nat_addr)); 823 return 0; 824 } 825 /* Build reply for the requesting host, use the original local port. */ 826 (void)snprintf(buf, sizeof(buf), "%d,%d:%s", lport, fport, p); 827 828 /* Send the reply from the NAT host back to the requesting host. */ 829 if (send(fd, buf, strlen(buf), 0) < 0) { 830 maybe_syslog(LOG_ERR, "send: %m"); 831 return 0; 832 } 833 834 return 1; 835 } 836 837 /* Check if a .noident file exists in the user home directory. */ 838 static int 839 check_noident(const char *homedir) 840 { 841 struct stat sb; 842 char *path; 843 int ret; 844 845 if (homedir == NULL) 846 return 0; 847 if (asprintf(&path, "%s/.noident", homedir) < 0) 848 return 0; 849 ret = stat(path, &sb); 850 851 free(path); 852 return (ret == 0); 853 } 854 855 /* 856 * Check if a .ident file exists in the user home directory and 857 * return the contents of that file. 858 */ 859 static int 860 check_userident(const char *homedir, char *username, size_t len) 861 { 862 struct stat sb; 863 char *path, *p; 864 ssize_t n; 865 int fd; 866 867 if (len == 0 || homedir == NULL) 868 return 0; 869 if (asprintf(&path, "%s/.ident", homedir) < 0) 870 return 0; 871 if ((fd = open(path, O_RDONLY|O_NONBLOCK|O_NOFOLLOW, 0)) < 0) { 872 free(path); 873 return 0; 874 } 875 if (fstat(fd, &sb) < 0 || !S_ISREG(sb.st_mode)) { 876 (void)close(fd); 877 free(path); 878 return 0; 879 } 880 if ((n = read(fd, username, len - 1)) < 1) { 881 (void)close(fd); 882 free(path); 883 return 0; 884 } 885 username[n] = '\0'; 886 887 if ((p = strpbrk(username, "\r\n")) != NULL) 888 *p = '\0'; 889 890 (void)close(fd); 891 free(path); 892 return 1; 893 } 894 895 /* Generate a random string. */ 896 static void 897 random_string(char *str, size_t len) 898 { 899 static const char chars[] = "abcdefghijklmnopqrstuvwxyz1234567890"; 900 char *p; 901 902 if (len == 0) 903 return; 904 for (p = str; len > 1; len--) 905 *p++ = chars[arc4random() % (sizeof(chars) - 1)]; 906 *p = '\0'; 907 } 908 909 /* Change the output format. */ 910 static int 911 change_format(const char *format, struct passwd *pw, char *dest, size_t len) 912 { 913 struct group *gr; 914 const char *cp; 915 char **gmp; 916 size_t bp; 917 918 if (len == 0 || ((gr = getgrgid(pw->pw_gid)) == NULL)) 919 return 0; 920 921 for (bp = 0, cp = format; *cp != '\0' && bp < len - 1; cp++) { 922 if (*cp != '%') { 923 dest[bp++] = *cp; 924 continue; 925 } 926 if (*++cp == '\0') 927 break; 928 switch (*cp) { 929 case 'u': 930 (void)snprintf(&dest[bp], len - bp, "%s", pw->pw_name); 931 break; 932 case 'U': 933 (void)snprintf(&dest[bp], len - bp, "%d", pw->pw_uid); 934 break; 935 case 'g': 936 (void)snprintf(&dest[bp], len - bp, "%s", gr->gr_name); 937 break; 938 case 'G': 939 (void)snprintf(&dest[bp], len - bp, "%d", gr->gr_gid); 940 break; 941 case 'l': 942 (void)snprintf(&dest[bp], len - bp, "%s", gr->gr_name); 943 bp += strlen(&dest[bp]); 944 if (bp >= len) 945 break; 946 setgrent(); 947 while ((gr = getgrent()) != NULL) { 948 if (gr->gr_gid == pw->pw_gid) 949 continue; 950 for (gmp = gr->gr_mem; *gmp && **gmp; gmp++) { 951 if (strcmp(*gmp, pw->pw_name) == 0) { 952 (void)snprintf(&dest[bp], 953 len - bp, ",%s", 954 gr->gr_name); 955 bp += strlen(&dest[bp]); 956 break; 957 } 958 } 959 if (bp >= len) 960 break; 961 } 962 endgrent(); 963 break; 964 case 'L': 965 (void)snprintf(&dest[bp], len - bp, "%u", gr->gr_gid); 966 bp += strlen(&dest[bp]); 967 if (bp >= len) 968 break; 969 setgrent(); 970 while ((gr = getgrent()) != NULL) { 971 if (gr->gr_gid == pw->pw_gid) 972 continue; 973 for (gmp = gr->gr_mem; *gmp && **gmp; gmp++) { 974 if (strcmp(*gmp, pw->pw_name) == 0) { 975 (void)snprintf(&dest[bp], 976 len - bp, ",%u", 977 gr->gr_gid); 978 bp += strlen(&dest[bp]); 979 break; 980 } 981 } 982 if (bp >= len) 983 break; 984 } 985 endgrent(); 986 break; 987 default: 988 dest[bp] = *cp; 989 dest[bp+1] = '\0'; 990 break; 991 } 992 bp += strlen(&dest[bp]); 993 } 994 dest[bp] = '\0'; 995 996 return 1; 997 } 998 999 /* Just exit when we caught SIGALRM. */ 1000 static void 1001 timeout_handler(int __unused s) 1002 { 1003 maybe_syslog(LOG_INFO, "Timeout for request, closing connection..."); 1004 exit(EXIT_FAILURE); 1005 } 1006 1007 /* Report error message string through syslog and quit. */ 1008 static void 1009 fatal(const char *func) 1010 { 1011 maybe_syslog(LOG_ERR, "%s: %m", func); 1012 exit(EXIT_FAILURE); 1013 } 1014 1015 /* 1016 * Report an error through syslog and/or stderr and quit. Only used when 1017 * running identd in the background and when it isn't a daemon yet. 1018 */ 1019 static void 1020 die(const char *message, ...) 1021 { 1022 va_list ap; 1023 1024 va_start(ap, message); 1025 if (bflag) 1026 vwarnx(message, ap); 1027 if (lflag) 1028 vsyslog(LOG_ERR, message, ap); 1029 va_end(ap); 1030 1031 exit(EXIT_FAILURE); 1032 } 1033 1034 /* Log using syslog, but only if enabled with the -l flag. */ 1035 void 1036 maybe_syslog(int priority, const char *message, ...) 1037 { 1038 va_list ap; 1039 1040 if (lflag) { 1041 va_start(ap, message); 1042 vsyslog(priority, message, ap); 1043 va_end(ap); 1044 } 1045 } 1046
Indexes created Wed Sep 24 05:09:52 GMT 2025