identd.c revision 1.13
1 /* $NetBSD: identd.c,v 1.13 2002/09/18 20:17:55 mycroft Exp $ */ 2 3 /* 4 ** identd.c A TCP/IP link identification protocol server 5 ** 6 ** This program is in the public domain and may be used freely by anyone 7 ** who wants to. 8 ** 9 ** Last update: 7 Oct 1993 10 ** 11 ** Please send bug fixes/bug reports to: Peter Eriksson <pen (at) lysator.liu.se> 12 */ 13 14 #if defined(IRIX) || defined(SVR4) || defined(NeXT) || (defined(sco) && sco >= 42) || defined(_AIX4) || defined(__NetBSD__) || defined(__FreeBSD__) || defined(ultrix) 15 # define SIGRETURN_TYPE void 16 # define SIGRETURN_TYPE_IS_VOID 17 #else 18 # define SIGRETURN_TYPE int 19 #endif 20 21 #ifdef SVR4 22 # define STRNET 23 #endif 24 25 #ifdef NeXT31 26 # include <libc.h> 27 #endif 28 29 #ifdef sco 30 # define USE_SIGALARM 31 #endif 32 33 #include <stdio.h> 34 #include <ctype.h> 35 #include <errno.h> 36 #include <netdb.h> 37 #include <signal.h> 38 #include <fcntl.h> 39 40 #include <sys/types.h> 41 #include <sys/param.h> 42 #include <sys/ioctl.h> 43 #include <sys/socket.h> 44 #include <sys/poll.h> 45 #ifndef _AUX_SOURCE 46 # include <sys/file.h> 47 #endif 48 #include <sys/time.h> 49 #include <sys/wait.h> 50 51 #include <pwd.h> 52 #include <grp.h> 53 54 #include <netinet/in.h> 55 56 #ifndef HPUX7 57 # include <arpa/inet.h> 58 #endif 59 60 #if defined(MIPS) || defined(BSD43) 61 extern int errno; 62 #endif 63 64 #if defined(SOLARIS) || defined(__NetBSD__) || defined(__FreeBSD__) || defined(__linux__) || defined(_AIX) 65 # include <unistd.h> 66 # include <stdlib.h> 67 # include <string.h> 68 #endif 69 70 #include "identd.h" 71 #include "error.h" 72 #include "paths.h" 73 74 75 /* Antique unixes do not have these things defined... */ 76 #ifndef FD_SETSIZE 77 # define FD_SETSIZE 256 78 #endif 79 80 #ifndef FD_SET 81 # ifndef NFDBITS 82 # define NFDBITS (sizeof(int) * NBBY) /* bits per mask */ 83 # endif 84 # define FD_SET(n, p) ((p)->fds_bits[(n)/NFDBITS] |= (1 << ((n) % NFDBITS))) 85 #endif 86 87 #ifndef FD_ZERO 88 # define FD_ZERO(p) bzero((char *)(p), sizeof(*(p))) 89 #endif 90 91 92 char *path_unix = (char *) NULL; 93 char *path_kmem = (char *) NULL; 94 95 int verbose_flag = 0; 96 int debug_flag = 0; 97 int syslog_flag = 0; 98 int multi_flag = 0; 99 int other_flag = 0; 100 int unknown_flag = 0; 101 int noident_flag = 0; 102 int crypto_flag = 0; 103 int liar_flag = 0; 104 105 int lport = 0; 106 int fport = 0; 107 108 char *charset_name = (char *) NULL; 109 char *indirect_host = (char *) NULL; 110 char *indirect_password = (char *) NULL; 111 char *lie_string = (char *) NULL; 112 113 #ifdef ALLOW_FORMAT 114 int format_flag = 0; 115 char *format = "%u"; 116 #endif 117 118 static int child_pid; 119 120 #ifdef LOG_DAEMON 121 static int syslog_facility = LOG_DAEMON; 122 #endif 123 124 static int comparemem __P((void *, void *, int)); 125 char *clearmem __P((void *, int)); 126 static SIGRETURN_TYPE child_handler __P((int)); 127 int main __P((int, char *[])); 128 129 /* 130 ** The structure passing convention for GCC is incompatible with 131 ** Suns own C compiler, so we define our own inet_ntoa() function. 132 ** (This should only affect GCC version 1 I think, a well, this works 133 ** for version 2 also so why bother.. :-) 134 */ 135 #if defined(__GNUC__) && defined(__sparc__) && !defined(NeXT) 136 137 #ifdef inet_ntoa 138 #undef inet_ntoa 139 #endif 140 141 char *inet_ntoa(ad) 142 struct in_addr ad; 143 { 144 unsigned long int s_ad; 145 int a, b, c, d; 146 static char addr[20]; 147 148 s_ad = ad.s_addr; 149 d = s_ad % 256; 150 s_ad /= 256; 151 c = s_ad % 256; 152 s_ad /= 256; 153 b = s_ad % 256; 154 a = s_ad / 256; 155 sprintf(addr, "%d.%d.%d.%d", a, b, c, d); 156 157 return addr; 158 } 159 #endif 160 161 static int comparemem(vp1, vp2, len) 162 void *vp1; 163 void *vp2; 164 int len; 165 { 166 unsigned char *p1 = (unsigned char *) vp1; 167 unsigned char *p2 = (unsigned char *) vp2; 168 int c; 169 170 while (len-- > 0) 171 if ((c = (int) *p1++ - (int) *p2++) != 0) 172 return c; 173 174 return 0; 175 } 176 177 /* 178 ** Return the name of the connecting host, or the IP number as a string. 179 */ 180 char *gethost(addr) 181 struct in_addr *addr; 182 { 183 int i; 184 struct hostent *hp; 185 186 187 hp = gethostbyaddr((char *) addr, sizeof(struct in_addr), AF_INET); 188 if (hp) 189 { 190 char *hname = strdup(hp->h_name); 191 192 if (! hname) { 193 syslog(LOG_ERR, "strdup(%s): %m", hp->h_name); 194 exit(1); 195 } 196 /* Found a IP -> Name match, now try the reverse for security reasons */ 197 hp = gethostbyname(hname); 198 (void) free(hname); 199 if (hp) 200 #ifdef h_addr 201 for (i = 0; hp->h_addr_list[i]; i++) 202 if (comparemem(hp->h_addr_list[i], 203 (unsigned char *) addr, 204 (int) sizeof(struct in_addr)) == 0) 205 return (char *) hp->h_name; 206 #else 207 if (comparemem(hp->h_addr, addr, sizeof(struct in_addr)) == 0) 208 return hp->h_name; 209 #endif 210 } 211 212 return inet_ntoa(*addr); 213 } 214 215 #ifdef USE_SIGALARM 216 /* 217 ** Exit cleanly after our time's up. 218 */ 219 static SIGRETURN_TYPE 220 alarm_handler(int s) 221 { 222 if (syslog_flag) 223 syslog(LOG_DEBUG, "SIGALRM triggered, exiting"); 224 225 exit(0); 226 } 227 #endif 228 229 230 #if !defined(hpux) && !defined(__hpux) && !defined(SVR4) && \ 231 !defined(_CRAY) && !defined(sco) && !defined(LINUX) 232 /* 233 ** This is used to clean up zombie child processes 234 ** if the -w or -b options are used. 235 */ 236 static SIGRETURN_TYPE 237 child_handler(dummy) 238 int dummy; 239 { 240 #if defined(NeXT) || (defined(__sgi) && defined(__SVR3)) 241 union wait status; 242 #else 243 int status; 244 #endif 245 int saved_errno = errno; 246 247 while (wait3(&status, WNOHANG, NULL) > 0) 248 ; 249 250 errno = saved_errno; 251 252 #ifndef SIGRETURN_TYPE_IS_VOID 253 return 0; 254 #endif 255 } 256 #endif 257 258 259 char *clearmem(vbp, len) 260 void *vbp; 261 int len; 262 { 263 char *bp = (char *) vbp; 264 char *cp; 265 266 cp = bp; 267 while (len-- > 0) 268 *cp++ = 0; 269 270 return bp; 271 } 272 273 274 /* 275 ** Main entry point into this daemon 276 */ 277 int main(argc,argv) 278 int argc; 279 char *argv[]; 280 { 281 int i, len; 282 struct sockaddr_in sin; 283 struct in_addr laddr, faddr; 284 int one = 1; 285 286 int background_flag = 0; 287 int timeout = 0; 288 char *portno = "113"; 289 char *bind_address = (char *) NULL; 290 int set_uid = 0; 291 int set_gid = 0; 292 int inhibit_default_config = 0; 293 int opt_count = 0; /* Count of option flags */ 294 295 #ifdef __convex__ 296 argc--; /* get rid of extra argument passed by inetd */ 297 #endif 298 299 300 if (isatty(0)) 301 background_flag = 1; 302 303 /* 304 ** Prescan the arguments for "-f<config-file>" switches 305 */ 306 inhibit_default_config = 0; 307 for (i = 1; i < argc && argv[i][0] == '-'; i++) 308 if (argv[i][1] == 'f') 309 inhibit_default_config = 1; 310 311 /* 312 ** Parse the default config file - if it exists 313 */ 314 if (!inhibit_default_config) 315 parse_config(NULL, 1); 316 317 /* 318 ** Parse the command line arguments 319 */ 320 for (i = 1; i < argc && argv[i][0] == '-'; i++) { 321 opt_count++; 322 switch (argv[i][1]) 323 { 324 case 'b': /* Start as standalone daemon */ 325 background_flag = 1; 326 break; 327 328 case 'w': /* Start from Inetd, wait mode */ 329 background_flag = 2; 330 break; 331 332 case 'i': /* Start from Inetd, nowait mode */ 333 background_flag = 0; 334 break; 335 336 case 't': 337 timeout = atoi(argv[i]+2); 338 break; 339 340 case 'p': 341 portno = argv[i]+2; 342 break; 343 344 case 'a': 345 bind_address = argv[i]+2; 346 break; 347 348 case 'u': 349 if (isdigit(argv[i][2])) 350 set_uid = atoi(argv[i]+2); 351 else 352 { 353 struct passwd *pwd; 354 355 pwd = getpwnam(argv[i]+2); 356 if (!pwd) 357 ERROR1("no such user (%s) for -u option", argv[i]+2); 358 else 359 { 360 set_uid = pwd->pw_uid; 361 set_gid = pwd->pw_gid; 362 } 363 } 364 break; 365 366 case 'g': 367 if (isdigit(argv[i][2])) 368 set_gid = atoi(argv[i]+2); 369 else 370 { 371 struct group *grp; 372 373 grp = getgrnam(argv[i]+2); 374 if (!grp) 375 ERROR1("no such group (%s) for -g option", argv[i]+2); 376 else 377 set_gid = grp->gr_gid; 378 } 379 break; 380 381 case 'c': 382 charset_name = argv[i]+2; 383 break; 384 385 case 'r': 386 indirect_host = argv[i]+2; 387 break; 388 389 case 'l': /* Use the Syslog daemon for logging */ 390 syslog_flag++; 391 #ifdef LOG_DAEMON 392 openlog("identd", LOG_PID, syslog_facility); 393 #else 394 openlog("identd", LOG_PID); 395 #endif 396 break; 397 398 case 'o': 399 other_flag = 1; 400 break; 401 402 case 'e': 403 unknown_flag = 1; 404 break; 405 406 case 'V': /* Give version of this daemon */ 407 printf("[in.identd, version %s]\r\n", version); 408 exit(0); 409 break; 410 411 case 'v': /* Be verbose */ 412 verbose_flag++; 413 break; 414 415 case 'd': /* Enable debugging */ 416 debug_flag++; 417 break; 418 419 case 'm': /* Enable multiline queries */ 420 multi_flag++; 421 break; 422 423 case 'N': /* Enable users ".noident" files */ 424 noident_flag++; 425 break; 426 427 #ifdef INCLUDE_CRYPT 428 case 'C': /* Enable encryption. */ 429 { 430 FILE *keyfile; 431 432 if (argv[i][2]) 433 keyfile = fopen(argv[i]+2, "r"); 434 else 435 keyfile = fopen(PATH_DESKEY, "r"); 436 437 if (keyfile == NULL) 438 { 439 ERROR("cannot open key file for option -C"); 440 } 441 else 442 { 443 char buf[1024]; 444 445 if (fgets(buf, 1024, keyfile) == NULL) 446 { 447 ERROR("cannot read key file for option -C"); 448 } 449 else 450 { 451 init_encryption(buf); 452 crypto_flag++; 453 } 454 fclose(keyfile); 455 } 456 } 457 break; 458 #endif 459 460 #ifdef ALLOW_FORMAT 461 case 'n': /* Compatibility flag - just send the user number */ 462 format_flag = 1; 463 format = "%U"; 464 break; 465 466 case 'F': /* Output format */ 467 format_flag = 1; 468 format = argv[i]+2; 469 break; 470 #endif 471 472 case 'L': /* lie brazenly */ 473 liar_flag = 1; 474 if (*(argv[i]+2) != '\0') 475 lie_string = argv[i]+2; 476 else 477 #ifdef DEFAULT_LIE_USER 478 lie_string = DEFAULT_LIE_USER; 479 #else 480 ERROR("-L specified with no user name"); 481 #endif 482 break; 483 484 default: 485 ERROR1("Bad option %s", argv[i]); 486 break; 487 } 488 } 489 490 #if defined(_AUX_SOURCE) || defined (SUNOS35) 491 /* A/UX 2.0* & SunOS 3.5 calls us with an argument XXXXXXXX.YYYY 492 ** where XXXXXXXXX is the hexadecimal version of the callers 493 ** IP number, and YYYY is the port/socket or something. 494 ** It seems to be impossible to pass arguments to a daemon started 495 ** by inetd. 496 ** 497 ** Just in case it is started from something else, then we only 498 ** skip the argument if no option flags have been seen. 499 */ 500 if (opt_count == 0) 501 argc--; 502 #endif 503 504 /* 505 ** Path to kernel namelist file specified on command line 506 */ 507 if (i < argc) 508 path_unix = argv[i++]; 509 510 /* 511 ** Path to kernel memory device specified on command line 512 */ 513 if (i < argc) 514 path_kmem = argv[i++]; 515 516 517 if (i < argc) 518 ERROR1("Too many arguments: ignored from %s", argv[i]); 519 520 521 /* 522 ** We used to call k_open here. But then the file descriptor 523 ** kd->fd open on /dev/kmem is shared by all child processes. 524 ** From the fork(2) man page: 525 ** o The child process has its own copy of the parent's descriptors. These 526 ** descriptors reference the same underlying objects. For instance, file 527 ** pointers in file objects are shared between the child and the parent 528 ** so that an lseek(2) on a descriptor in the child process can affect a 529 ** subsequent read(2) or write(2) by the parent. 530 ** Thus with concurrent (simultaneous) identd client processes, 531 ** they step on each other's toes when they use kvm_read. 532 ** 533 ** Calling k_open here was a mistake for another reason too: we 534 ** did not yet honor -u and -g options. Presumably we are 535 ** running as root (unless the in.identd file is setuid), and 536 ** then we can open kmem regardless of -u and -g values. 537 ** 538 ** 539 ** Open the kernel memory device and read the nlist table 540 ** 541 ** if (k_open() < 0) 542 ** ERROR("main: k_open"); 543 */ 544 545 /* 546 ** Do the special handling needed for the "-b" flag 547 */ 548 if (background_flag == 1) 549 { 550 struct sockaddr_in addr; 551 struct servent *sp; 552 int fd; 553 554 555 if (!debug_flag) 556 { 557 if (fork()) 558 exit(0); 559 560 close(0); 561 close(1); 562 close(2); 563 564 if (fork()) 565 exit(0); 566 } 567 568 fd = socket(AF_INET, SOCK_STREAM, 0); 569 if (fd == -1) 570 ERROR("main: socket"); 571 572 if (fd != 0) 573 dup2(fd, 0); 574 575 clearmem((void *) &addr, (int) sizeof(addr)); 576 577 addr.sin_family = AF_INET; 578 if (bind_address == (char *) NULL) 579 addr.sin_addr.s_addr = htonl(INADDR_ANY); 580 else 581 { 582 if (isdigit(bind_address[0])) 583 addr.sin_addr.s_addr = inet_addr(bind_address); 584 else 585 { 586 struct hostent *hp; 587 588 hp = gethostbyname(bind_address); 589 if (!hp) 590 ERROR1("no such address (%s) for -a switch", bind_address); 591 592 /* This is ugly, should use memcpy() or bcopy() but... */ 593 addr.sin_addr.s_addr = * (unsigned long *) (hp->h_addr); 594 } 595 } 596 597 if (isdigit(portno[0])) 598 addr.sin_port = htons(atoi(portno)); 599 else 600 { 601 sp = getservbyname(portno, "tcp"); 602 if (sp == (struct servent *) NULL) 603 ERROR1("main: getservbyname: %s", portno); 604 addr.sin_port = sp->s_port; 605 } 606 607 #ifdef SO_REUSEADDR 608 setsockopt(0, SOL_SOCKET, SO_REUSEADDR, (void *) &one, sizeof(one)); 609 #endif 610 611 if (bind(0, (struct sockaddr *) &addr, sizeof(addr)) < 0) 612 ERROR("main: bind"); 613 } 614 615 if (background_flag) 616 { 617 if (listen(0, 3) < 0) 618 ERROR("main: listen"); 619 } 620 621 if (set_gid) 622 { 623 if (setgid(set_gid) == -1) 624 ERROR("main: setgid"); 625 /* Call me paranoid... PSz */ 626 if (getgid() != set_gid) 627 ERROR2("main: setgid failed: wanted %d, got GID %d", set_gid, getgid()); 628 if (getegid() != set_gid) 629 ERROR2("main: setgid failed: wanted %d, got EGID %d", set_gid, getegid()); 630 } 631 632 if (set_uid) 633 { 634 if (setuid(set_uid) == -1) 635 ERROR("main: setuid"); 636 /* Call me paranoid... PSz */ 637 if (getuid() != set_uid) 638 ERROR2("main: setuid failed: wanted %d, got UID %d", set_uid, getuid()); 639 if (geteuid() != set_uid) 640 ERROR2("main: setuid failed: wanted %d, got EUID %d", set_uid, geteuid()); 641 } 642 643 /* 644 ** Do some special handling if the "-b" or "-w" flags are used 645 */ 646 if (background_flag) 647 { 648 int nfds, fd; 649 struct pollfd set[1]; 650 struct sockaddr sad; 651 int sadlen; 652 653 654 /* 655 ** Set up the SIGCHLD signal child termination handler so 656 ** that we can avoid zombie processes hanging around and 657 ** handle childs terminating before being able to complete the 658 ** handshake. 659 */ 660 #if (defined(SVR4) || defined(hpux) || defined(__hpux) || defined(IRIX) || \ 661 defined(_CRAY) || defined(_AUX_SOURCE) || defined(sco) || \ 662 defined(LINUX)) 663 signal(SIGCHLD, SIG_IGN); 664 #else 665 signal(SIGCHLD, child_handler); 666 #endif 667 668 set[0].fd = 0; 669 set[0].events = POLLIN; 670 671 /* 672 ** Loop and dispatch client handling processes 673 */ 674 do 675 { 676 #ifdef USE_SIGALARM 677 /* 678 ** Terminate if we've been idle for 'timeout' seconds 679 */ 680 if (background_flag == 2 && timeout) 681 { 682 signal(SIGALRM, alarm_handler); 683 alarm(timeout); 684 } 685 #endif 686 687 /* 688 ** Wait for a connection request to occur. 689 ** Ignore EINTR (Interrupted System Call). 690 */ 691 do 692 { 693 #ifndef USE_SIGALARM 694 if (timeout) 695 nfds = poll(set, 1, timeout * 1000); 696 else 697 #endif 698 nfds = poll(set, 1, INFTIM); 699 } while (nfds < 0 && errno == EINTR); 700 701 /* 702 ** An error occurred in select? Just die 703 */ 704 if (nfds < 0) 705 ERROR("main: select"); 706 707 /* 708 ** Timeout limit reached. Exit nicely 709 */ 710 if (nfds == 0) 711 exit(0); 712 713 #ifdef USE_SIGALARM 714 /* 715 ** Disable the alarm timeout 716 */ 717 alarm(0); 718 #endif 719 720 /* 721 ** Accept the new client 722 */ 723 sadlen = sizeof(sad); 724 errno = 0; 725 fd = accept(0, &sad, &sadlen); 726 if (fd == -1) 727 ERROR1("main: accept. errno = %d", errno); 728 729 /* 730 ** And fork, then close the fd if we are the parent. 731 */ 732 child_pid = fork(); 733 } while (child_pid && (close(fd), 1)); 734 735 /* 736 ** We are now in child, the parent has returned to "do" above. 737 */ 738 if (dup2(fd, 0) == -1) 739 ERROR("main: dup2: failed fd 0"); 740 741 if (dup2(fd, 1) == -1) 742 ERROR("main: dup2: failed fd 1"); 743 744 if (dup2(fd, 2) == -1) 745 ERROR("main: dup2: failed fd 2"); 746 } 747 748 /* 749 ** Get foreign internet address 750 */ 751 len = sizeof(sin); 752 if (getpeername(0, (struct sockaddr *) &sin, &len) == -1) 753 { 754 /* 755 ** A user has tried to start us from the command line or 756 ** the network link died, in which case this message won't 757 ** reach to other end anyway, so lets give the poor user some 758 ** errors. 759 */ 760 perror("in.identd: getpeername()"); 761 exit(1); 762 } 763 764 faddr = sin.sin_addr; 765 766 767 #ifdef STRONG_LOG 768 if (syslog_flag) 769 syslog(LOG_INFO, "Connection from %s", gethost(&faddr)); 770 #endif 771 772 773 /* 774 ** Get local internet address 775 */ 776 len = sizeof(sin); 777 #ifdef ATTSVR4 778 if (t_getsockname(0, (struct sockaddr *) &sin, &len) == -1) 779 #else 780 if (getsockname(0, (struct sockaddr *) &sin, &len) == -1) 781 #endif 782 { 783 /* 784 ** We can just die here, because if this fails then the 785 ** network has died and we haven't got anyone to return 786 ** errors to. 787 */ 788 exit(1); 789 } 790 laddr = sin.sin_addr; 791 792 793 /* 794 ** Get the local/foreign port pair from the luser 795 */ 796 parse(stdin, &laddr, &faddr); 797 798 exit(0); 799 } 800
Indexes created Wed Sep 24 05:09:52 GMT 2025