identd.c revision 1.30
1 /* $NetBSD: identd.c,v 1.30 2006/09/29 15:49:29 christos 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 1.30 2006/09/29 15:49:29 christos 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 ssize_t qlen; 329 330 lport = fport = 0; 331 332 (void)strlcpy(idbuf, user, sizeof(idbuf)); 333 (void)signal(SIGALRM, timeout_handler); 334 (void)alarm(timeout); 335 336 /* Get foreign internet address. */ 337 len = sizeof(ss[0]); 338 if (getpeername(fd, (struct sockaddr *)&ss[0], &len) < 0) 339 fatal("getpeername"); 340 341 maybe_syslog(LOG_INFO, "Connection from %s", 342 gethost((struct sockaddr *)&ss[0])); 343 344 /* Get local internet address. */ 345 len = sizeof(ss[1]); 346 if (getsockname(fd, (struct sockaddr *)&ss[1], &len) < 0) 347 fatal("getsockname"); 348 349 /* Be sure to have the same address families. */ 350 if (ss[0].ss_family != ss[1].ss_family) { 351 maybe_syslog(LOG_ERR, "Different foreign/local address family"); 352 return 1; 353 } 354 355 /* Receive data from the client. */ 356 qlen = 0; 357 for (;;) { 358 if ((n = recv(fd, &buf[qlen], sizeof(buf) - qlen, 0)) < 0) { 359 fatal("recv"); 360 } else if (n == 0) { 361 maybe_syslog(LOG_NOTICE, "recv: EOF"); 362 iderror(fd, 0, 0, "UNKNOWN-ERROR"); 363 return 1; 364 } 365 /* 366 * 1413 is not clear on what to do if data follows the first 367 * CRLF before we respond. We do not consider the query 368 * complete until we get a CRLF _at the end of the buffer_. 369 */ 370 qlen += n; 371 if ((qlen >= 2) && (buf[qlen - 2] == '\r') && 372 (buf[qlen - 1] == '\n')) 373 break; 374 } 375 buf[qlen - 2] = '\0'; 376 377 /* Get local and remote ports from the received data. */ 378 p = buf; 379 while (*p != '\0' && isspace((unsigned char)*p)) 380 p++; 381 if ((p = strtok(p, " \t,")) != NULL) { 382 lport = atoi(p); 383 if ((p = strtok(NULL, " \t,")) != NULL) 384 fport = atoi(p); 385 } 386 387 /* Are the ports valid? */ 388 if (lport < 1 || lport > 65535 || fport < 1 || fport > 65535) { 389 maybe_syslog(LOG_NOTICE, "Invalid port(s): %d, %d from %s", 390 lport, fport, gethost((struct sockaddr *)&ss[0])); 391 iderror(fd, 0, 0, eflag ? "UNKNOWN-ERROR" : "INVALID-PORT"); 392 return 1; 393 } 394 395 /* If there is a 'lie' user enabled, then handle it now and stop. */ 396 if (Lflag) { 397 maybe_syslog(LOG_NOTICE, "Lying with name %s to %s", 398 idbuf, gethost((struct sockaddr *)&ss[0])); 399 idparse(fd, lport, fport, charset, osname, idbuf); 400 return 0; 401 } 402 403 /* Protocol dependent stuff. */ 404 switch (ss[0].ss_family) { 405 case AF_INET: 406 satosin(&ss[0])->sin_port = htons(fport); 407 satosin(&ss[1])->sin_port = htons(lport); 408 break; 409 case AF_INET6: 410 satosin6(&ss[0])->sin6_port = htons(fport); 411 satosin6(&ss[1])->sin6_port = htons(lport); 412 break; 413 default: 414 maybe_syslog(LOG_ERR, "Unsupported protocol (no. %d)", 415 ss[0].ss_family); 416 return 1; 417 } 418 419 /* Try to get the UID of the connection owner using sysctl. */ 420 if (ident_getuid(ss, sizeof(ss), proxy, &uid) == -1) { 421 /* Lookup failed, try to forward if enabled. */ 422 if (nat_lookup != NULL) { 423 struct sockaddr nat_addr; 424 int nat_lport; 425 426 (void)memset(&nat_addr, 0, sizeof(nat_addr)); 427 428 if ((*nat_lookup)(ss, &nat_addr, &nat_lport) && 429 forward(fd, &nat_addr, nat_lport, fport, lport)) { 430 maybe_syslog(LOG_INFO, 431 "Succesfully forwarded the request to %s", 432 gethost(&nat_addr)); 433 return 0; 434 } 435 } 436 /* Fall back to a default name? */ 437 if (fflag) { 438 maybe_syslog(LOG_NOTICE, "Using fallback name %s to %s", 439 idbuf, gethost((struct sockaddr *)&ss[0])); 440 idparse(fd, lport, fport, charset, osname, idbuf); 441 return 0; 442 } 443 maybe_syslog(LOG_ERR, "Lookup failed, returning error to %s", 444 gethost((struct sockaddr *)&ss[0])); 445 iderror(fd, lport, fport, eflag ? "UNKNOWN-ERROR" : "NO-USER"); 446 return 1; 447 } 448 449 /* Fill in userbuf with user name if possible, else numeric UID. */ 450 if ((pw = getpwuid(uid)) == NULL) { 451 maybe_syslog(LOG_ERR, "Couldn't map uid (%u) to name", uid); 452 (void)snprintf(userbuf, sizeof(userbuf), "%u", uid); 453 } else { 454 maybe_syslog(LOG_INFO, "Successful lookup: %d, %d: %s for %s", 455 lport, fport, pw->pw_name, 456 gethost((struct sockaddr *)&ss[0])); 457 (void)strlcpy(userbuf, pw->pw_name, sizeof(userbuf)); 458 } 459 460 /* No ident enabled? */ 461 if (Nflag && pw && check_noident(pw->pw_dir)) { 462 maybe_syslog(LOG_NOTICE, "Returning HIDDEN-USER for user %s" 463 " to %s", pw->pw_name, gethost((struct sockaddr *)&ss[0])); 464 iderror(fd, lport, fport, "HIDDEN-USER"); 465 return 1; 466 } 467 468 /* User ident enabled? */ 469 if (iflag && pw && check_userident(pw->pw_dir, idbuf, sizeof(idbuf))) { 470 if (!Iflag) { 471 if ((strspn(idbuf, "0123456789") && 472 getpwuid(atoi(idbuf)) != NULL) || 473 (getpwnam(idbuf) != NULL)) { 474 maybe_syslog(LOG_NOTICE, 475 "Ignoring user-specified '%s' for user %s", 476 idbuf, userbuf); 477 (void)strlcpy(idbuf, userbuf, sizeof(idbuf)); 478 } 479 } 480 maybe_syslog(LOG_NOTICE, 481 "Returning user-specified '%s' for user %s to %s", 482 idbuf, userbuf, gethost((struct sockaddr *)&ss[0])); 483 idparse(fd, lport, fport, charset, osname, idbuf); 484 return 0; 485 } 486 487 /* Send a random message? */ 488 if (rflag) { 489 /* Random number or string? */ 490 if (nflag) 491 (void)snprintf(idbuf, sizeof(idbuf), "%u", 492 (unsigned int)(arc4random() % 65535)); 493 else 494 random_string(idbuf, sizeof(idbuf)); 495 496 maybe_syslog(LOG_NOTICE, 497 "Returning random '%s' for user %s to %s", 498 idbuf, userbuf, gethost((struct sockaddr *)&ss[0])); 499 idparse(fd, lport, fport, charset, osname, idbuf); 500 return 0; 501 } 502 503 /* Return numberic user ID? */ 504 if (nflag) 505 (void)snprintf(idbuf, sizeof(idbuf), "%u", uid); 506 else 507 (void)strlcpy(idbuf, userbuf, sizeof(idbuf)); 508 509 /* 510 * Change the output format? Note that 512 is the maximum 511 * size of the result according to RFC 1413. 512 */ 513 if (fmt && change_format(fmt, pw, buf, 512 + 1)) 514 idparse(fd, lport, fport, charset, osname, buf); 515 else 516 idparse(fd, lport, fport, charset, osname, idbuf); 517 518 return 0; 519 } 520 521 /* Send/parse the ident result. */ 522 static void 523 idparse(int fd, int lport, int fport, const char *charset, const char *osname, 524 const char *user) 525 { 526 char *p; 527 528 if (asprintf(&p, "%d,%d:USERID:%s%s%s:%s\r\n", lport, fport, 529 osname, charset ? "," : "", charset ? charset : "", user) < 0) 530 fatal("asprintf"); 531 if (send(fd, p, strlen(p), 0) < 0) { 532 free(p); 533 fatal("send"); 534 } 535 free(p); 536 } 537 538 /* Return a specified ident error. */ 539 static void 540 iderror(int fd, int lport, int fport, const char *error) 541 { 542 char *p; 543 544 if (asprintf(&p, "%d,%d:ERROR:%s\r\n", lport, fport, error) < 0) 545 fatal("asprintf"); 546 if (send(fd, p, strlen(p), 0) < 0) { 547 free(p); 548 fatal("send"); 549 } 550 free(p); 551 } 552 553 /* Return the IP address of the connecting host. */ 554 static const char * 555 gethost(struct sockaddr *sa) 556 { 557 static char host[NI_MAXHOST]; 558 559 if (getnameinfo(sa, sa->sa_len, host, sizeof(host), 560 NULL, 0, NI_NUMERICHOST) == 0) 561 return host; 562 563 return "UNKNOWN"; 564 } 565 566 /* Setup sockets, for daemon mode. */ 567 static int * 568 socketsetup(const char *address, const char *port, int af) 569 { 570 struct addrinfo hints, *res, *res0; 571 int error, maxs, *s, *socks; 572 const char *cause = NULL; 573 socklen_t y = 1; 574 575 (void)memset(&hints, 0, sizeof(hints)); 576 hints.ai_flags = AI_PASSIVE; 577 hints.ai_family = af; 578 hints.ai_socktype = SOCK_STREAM; 579 error = getaddrinfo(address, port, &hints, &res0); 580 if (error) { 581 die("getaddrinfo: %s", gai_strerror(error)); 582 /* NOTREACHED */ 583 } 584 585 /* Count max number of sockets we may open. */ 586 for (maxs = 0, res = res0; res != NULL; res = res->ai_next) 587 maxs++; 588 589 socks = malloc((maxs + 1) * sizeof(int)); 590 if (socks == NULL) { 591 die("malloc: %s", strerror(errno)); 592 /* NOTREACHED */ 593 } 594 595 *socks = 0; 596 s = socks + 1; 597 for (res = res0; res != NULL; res = res->ai_next) { 598 *s = socket(res->ai_family, res->ai_socktype, res->ai_protocol); 599 if (*s < 0) { 600 cause = "socket"; 601 continue; 602 } 603 (void)setsockopt(*s, SOL_SOCKET, SO_REUSEADDR, &y, sizeof(y)); 604 if (bind(*s, res->ai_addr, res->ai_addrlen) < 0) { 605 cause = "bind"; 606 (void)close(*s); 607 continue; 608 } 609 if (listen(*s, 5) < 0) { 610 cause = "listen"; 611 (void)close(*s); 612 continue; 613 } 614 *socks = *socks + 1; 615 s++; 616 } 617 618 if (*socks == 0) { 619 free(socks); 620 die("%s: %s", cause, strerror(errno)); 621 /* NOTREACHED */ 622 } 623 if (res0) 624 freeaddrinfo(res0); 625 626 return socks; 627 } 628 629 /* UID lookup wrapper. */ 630 static int 631 ident_getuid(struct sockaddr_storage *ss, socklen_t len, 632 struct sockaddr *proxy, uid_t *uid) 633 { 634 int rc; 635 636 rc = sysctl_getuid(ss, len, uid); 637 if (rc == -1 && proxy != NULL) 638 rc = sysctl_proxy_getuid(ss, proxy, uid); 639 640 return rc; 641 } 642 643 /* Try to get the UID of the connection owner using sysctl. */ 644 static int 645 sysctl_getuid(struct sockaddr_storage *ss, socklen_t len, uid_t *uid) 646 { 647 int mib[4]; 648 uid_t myuid; 649 size_t uidlen; 650 651 uidlen = sizeof(myuid); 652 653 mib[0] = CTL_NET; 654 mib[1] = ss->ss_family; 655 mib[2] = IPPROTO_TCP; 656 mib[3] = TCPCTL_IDENT; 657 658 if (sysctl(mib, sizeof(mib)/ sizeof(int), &myuid, &uidlen, ss, len) < 0) 659 return -1; 660 *uid = myuid; 661 662 return 0; 663 } 664 665 /* Try to get the UID of the connection owner using sysctl (proxy version). */ 666 static int 667 sysctl_proxy_getuid(struct sockaddr_storage *ss, struct sockaddr *proxy, 668 uid_t *uid) 669 { 670 struct sockaddr_storage new[2]; 671 int i, rc, name[CTL_MAXNAME]; 672 struct kinfo_pcb *kp; 673 size_t sz, len; 674 const char *list; 675 676 rc = -1; 677 sz = CTL_MAXNAME; 678 list = NULL; 679 680 /* Retrieve a list of sockets. */ 681 switch (ss[0].ss_family) { 682 case AF_INET: 683 /* We only accept queries from the proxy. */ 684 if (in_hosteq(satosin(&ss[0])->sin_addr, 685 satosin(proxy)->sin_addr)) 686 list = "net.inet.tcp.pcblist"; 687 break; 688 case AF_INET6: 689 /* We only accept queries from the proxy. */ 690 if (IN6_ARE_ADDR_EQUAL(&satosin6(&ss[0])->sin6_addr, 691 &satosin6(proxy)->sin6_addr)) 692 list = "net.inet6.tcp.pcblist"; 693 break; 694 default: 695 maybe_syslog(LOG_ERR, "Unsupported protocol for proxy (no. %d)", 696 ss[0].ss_family); 697 } 698 if (list != NULL) 699 rc = sysctlnametomib(list, &name[0], &sz); 700 if (rc == -1) 701 return -1; 702 len = sz; 703 704 name[len++] = PCB_ALL; 705 name[len++] = 0; 706 name[len++] = sizeof(struct kinfo_pcb); 707 name[len++] = INT_MAX; 708 709 kp = NULL; 710 sz = 0; 711 do { 712 rc = sysctl(&name[0], len, kp, &sz, NULL, 0); 713 if (rc == -1 && errno != ENOMEM) 714 return -1; 715 if (kp == NULL) { 716 kp = malloc(sz); 717 rc = -1; 718 } 719 if (kp == NULL) 720 return -1; 721 } while (rc == -1); 722 723 rc = -1; 724 /* 725 * Walk through the list of sockets and try to find a match. 726 * We don't know who has sent the query (we only know that the 727 * proxy has forwarded to us) so just try to match the ports and 728 * the local address. 729 */ 730 for (i = 0; i < sz / sizeof(struct kinfo_pcb); i++) { 731 switch (ss[0].ss_family) { 732 case AF_INET: 733 /* Foreign and local ports must match. */ 734 if (satosin(&ss[0])->sin_port != 735 satosin(&kp[i].ki_src)->sin_port) 736 continue; 737 if (satosin(&ss[1])->sin_port != 738 satosin(&kp[i].ki_dst)->sin_port) 739 continue; 740 /* Foreign address may not match proxy address. */ 741 if (in_hosteq(satosin(proxy)->sin_addr, 742 satosin(&kp[i].ki_dst)->sin_addr)) 743 continue; 744 /* Local addresses must match. */ 745 if (!in_hosteq(satosin(&ss[1])->sin_addr, 746 satosin(&kp[i].ki_src)->sin_addr)) 747 continue; 748 break; 749 case AF_INET6: 750 /* Foreign and local ports must match. */ 751 if (satosin6(&ss[0])->sin6_port != 752 satosin6(&kp[i].ki_src)->sin6_port) 753 continue; 754 if (satosin6(&ss[1])->sin6_port != 755 satosin6(&kp[i].ki_dst)->sin6_port) 756 continue; 757 /* Foreign address may not match proxy address. */ 758 if (IN6_ARE_ADDR_EQUAL(&satosin6(proxy)->sin6_addr, 759 &satosin6(&kp[i].ki_dst)->sin6_addr)) 760 continue; 761 /* Local addresses must match. */ 762 if (!IN6_ARE_ADDR_EQUAL(&satosin6(&ss[1])->sin6_addr, 763 &satosin6(&kp[i].ki_src)->sin6_addr)) 764 continue; 765 break; 766 } 767 768 /* 769 * We have found the foreign address, copy it to a new 770 * struct and retrieve the UID of the connection owner. 771 */ 772 (void)memcpy(&new[0], &kp[i].ki_dst, kp[i].ki_dst.sa_len); 773 (void)memcpy(&new[1], &kp[i].ki_src, kp[i].ki_src.sa_len); 774 775 rc = sysctl_getuid(new, sizeof(new), uid); 776 777 /* Done. */ 778 break; 779 } 780 781 free(kp); 782 return rc; 783 } 784 785 /* Forward ident queries. Returns 1 when succesful, or zero if not. */ 786 static int 787 forward(int fd, struct sockaddr *nat_addr, int nat_lport, int fport, int lport) 788 { 789 char buf[BUFSIZ], reply[BUFSIZ], *p; 790 ssize_t n; 791 int sock; 792 793 /* Connect to the NAT host. */ 794 sock = socket(nat_addr->sa_family, SOCK_STREAM, 0); 795 if (sock < 0) { 796 maybe_syslog(LOG_ERR, "socket: %m"); 797 return 0; 798 } 799 if (connect(sock, nat_addr, nat_addr->sa_len) < 0) { 800 maybe_syslog(LOG_ERR, "Can't connect to %s: %m", 801 gethost(nat_addr)); 802 (void)close(sock); 803 return 0; 804 } 805 806 /* 807 * Send the ident query to the NAT host, but use as local port 808 * the port of the NAT host. 809 */ 810 (void)snprintf(buf, sizeof(buf), "%d , %d\r\n", nat_lport, fport); 811 if (send(sock, buf, strlen(buf), 0) < 0) { 812 maybe_syslog(LOG_ERR, "send: %m"); 813 (void)close(sock); 814 return 0; 815 } 816 817 /* Read the reply from the NAT host. */ 818 if ((n = recv(sock, reply, sizeof(reply) - 1, 0)) < 0) { 819 maybe_syslog(LOG_ERR, "recv: %m"); 820 (void)close(sock); 821 return 0; 822 } else if (n == 0) { 823 maybe_syslog(LOG_NOTICE, "recv: EOF"); 824 (void)close(sock); 825 return 0; 826 } 827 reply[n] = '\0'; 828 (void)close(sock); 829 830 /* Extract everything after the port specs from the ident reply. */ 831 for (p = reply; *p != '\0' && *p != ':'; p++) 832 continue; 833 if (*p == '\0' || *++p == '\0') { 834 maybe_syslog(LOG_ERR, "Malformed ident reply from %s", 835 gethost(nat_addr)); 836 return 0; 837 } 838 /* Build reply for the requesting host, use the original local port. */ 839 (void)snprintf(buf, sizeof(buf), "%d,%d:%s", lport, fport, p); 840 841 /* Send the reply from the NAT host back to the requesting host. */ 842 if (send(fd, buf, strlen(buf), 0) < 0) { 843 maybe_syslog(LOG_ERR, "send: %m"); 844 return 0; 845 } 846 847 return 1; 848 } 849 850 /* Check if a .noident file exists in the user home directory. */ 851 static int 852 check_noident(const char *homedir) 853 { 854 struct stat sb; 855 char *path; 856 int ret; 857 858 if (homedir == NULL) 859 return 0; 860 if (asprintf(&path, "%s/.noident", homedir) < 0) 861 return 0; 862 ret = stat(path, &sb); 863 864 free(path); 865 return (ret == 0); 866 } 867 868 /* 869 * Check if a .ident file exists in the user home directory and 870 * return the contents of that file. 871 */ 872 static int 873 check_userident(const char *homedir, char *username, size_t len) 874 { 875 struct stat sb; 876 char *path, *p; 877 ssize_t n; 878 int fd; 879 880 if (len == 0 || homedir == NULL) 881 return 0; 882 if (asprintf(&path, "%s/.ident", homedir) < 0) 883 return 0; 884 if ((fd = open(path, O_RDONLY|O_NONBLOCK|O_NOFOLLOW, 0)) < 0) { 885 free(path); 886 return 0; 887 } 888 if (fstat(fd, &sb) < 0 || !S_ISREG(sb.st_mode)) { 889 (void)close(fd); 890 free(path); 891 return 0; 892 } 893 if ((n = read(fd, username, len - 1)) < 1) { 894 (void)close(fd); 895 free(path); 896 return 0; 897 } 898 username[n] = '\0'; 899 900 if ((p = strpbrk(username, "\r\n")) != NULL) 901 *p = '\0'; 902 903 (void)close(fd); 904 free(path); 905 return 1; 906 } 907 908 /* Generate a random string. */ 909 static void 910 random_string(char *str, size_t len) 911 { 912 static const char chars[] = "abcdefghijklmnopqrstuvwxyz1234567890"; 913 char *p; 914 915 if (len == 0) 916 return; 917 for (p = str; len > 1; len--) 918 *p++ = chars[arc4random() % (sizeof(chars) - 1)]; 919 *p = '\0'; 920 } 921 922 /* Change the output format. */ 923 static int 924 change_format(const char *format, struct passwd *pw, char *dest, size_t len) 925 { 926 struct group *gr; 927 const char *cp; 928 char **gmp; 929 size_t bp; 930 931 if (len == 0 || ((gr = getgrgid(pw->pw_gid)) == NULL)) 932 return 0; 933 934 for (bp = 0, cp = format; *cp != '\0' && bp < len - 1; cp++) { 935 if (*cp != '%') { 936 dest[bp++] = *cp; 937 continue; 938 } 939 if (*++cp == '\0') 940 break; 941 switch (*cp) { 942 case 'u': 943 (void)snprintf(&dest[bp], len - bp, "%s", pw->pw_name); 944 break; 945 case 'U': 946 (void)snprintf(&dest[bp], len - bp, "%d", pw->pw_uid); 947 break; 948 case 'g': 949 (void)snprintf(&dest[bp], len - bp, "%s", gr->gr_name); 950 break; 951 case 'G': 952 (void)snprintf(&dest[bp], len - bp, "%d", gr->gr_gid); 953 break; 954 case 'l': 955 (void)snprintf(&dest[bp], len - bp, "%s", gr->gr_name); 956 bp += strlen(&dest[bp]); 957 if (bp >= len) 958 break; 959 setgrent(); 960 while ((gr = getgrent()) != NULL) { 961 if (gr->gr_gid == pw->pw_gid) 962 continue; 963 for (gmp = gr->gr_mem; *gmp && **gmp; gmp++) { 964 if (strcmp(*gmp, pw->pw_name) == 0) { 965 (void)snprintf(&dest[bp], 966 len - bp, ",%s", 967 gr->gr_name); 968 bp += strlen(&dest[bp]); 969 break; 970 } 971 } 972 if (bp >= len) 973 break; 974 } 975 endgrent(); 976 break; 977 case 'L': 978 (void)snprintf(&dest[bp], len - bp, "%u", gr->gr_gid); 979 bp += strlen(&dest[bp]); 980 if (bp >= len) 981 break; 982 setgrent(); 983 while ((gr = getgrent()) != NULL) { 984 if (gr->gr_gid == pw->pw_gid) 985 continue; 986 for (gmp = gr->gr_mem; *gmp && **gmp; gmp++) { 987 if (strcmp(*gmp, pw->pw_name) == 0) { 988 (void)snprintf(&dest[bp], 989 len - bp, ",%u", 990 gr->gr_gid); 991 bp += strlen(&dest[bp]); 992 break; 993 } 994 } 995 if (bp >= len) 996 break; 997 } 998 endgrent(); 999 break; 1000 default: 1001 dest[bp] = *cp; 1002 dest[bp+1] = '\0'; 1003 break; 1004 } 1005 bp += strlen(&dest[bp]); 1006 } 1007 dest[bp] = '\0'; 1008 1009 return 1; 1010 } 1011 1012 /* Just exit when we caught SIGALRM. */ 1013 static void 1014 timeout_handler(int __unused s) 1015 { 1016 maybe_syslog(LOG_INFO, "Timeout for request, closing connection..."); 1017 exit(EXIT_FAILURE); 1018 } 1019 1020 /* Report error message string through syslog and quit. */ 1021 static void 1022 fatal(const char *func) 1023 { 1024 maybe_syslog(LOG_ERR, "%s: %m", func); 1025 exit(EXIT_FAILURE); 1026 } 1027 1028 /* 1029 * Report an error through syslog and/or stderr and quit. Only used when 1030 * running identd in the background and when it isn't a daemon yet. 1031 */ 1032 static void 1033 die(const char *message, ...) 1034 { 1035 va_list ap; 1036 1037 va_start(ap, message); 1038 if (bflag) 1039 vwarnx(message, ap); 1040 if (lflag) 1041 vsyslog(LOG_ERR, message, ap); 1042 va_end(ap); 1043 1044 exit(EXIT_FAILURE); 1045 } 1046 1047 /* Log using syslog, but only if enabled with the -l flag. */ 1048 void 1049 maybe_syslog(int priority, const char *message, ...) 1050 { 1051 va_list ap; 1052 1053 if (lflag) { 1054 va_start(ap, message); 1055 vsyslog(priority, message, ap); 1056 va_end(ap); 1057 } 1058 } 1059
Indexes created Wed Sep 24 14:09:57 GMT 2025