1 /*- 2 * Copyright (c) 1990, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 33 34 #ifndef lint 35 static char copyright[] = 36 "@(#) Copyright (c) 1990, 1993\n\ 37 The Regents of the University of California. All rights reserved.\n"; 38 #endif /* not lint */ 39 40 #ifndef lint 41 static char sccsid[] = "@(#)sliplogin.c 8.2 (Berkeley) 2/1/94"; 42 static char rscid[] = "@(#)$FreeBSD: src/usr.sbin/sliplogin/sliplogin.c,v 1.9.6.2 2001/07/19 05:21:28 kris Exp $"; 43 #endif /* not lint */ 44 45 /* 46 * sliplogin.c 47 * [MUST BE RUN SUID, SLOPEN DOES A SUSER()!] 48 * 49 * This program initializes its own tty port to be an async TCP/IP interface. 50 * It sets the line discipline to slip, invokes a shell script to initialize 51 * the network interface, then pauses forever waiting for hangup. 52 * 53 * It is a remote descendant of several similar programs with incestuous ties: 54 * - Kirk Smith's slipconf, modified by Richard Johnsson @ DEC WRL. 55 * - slattach, probably by Rick Adams but touched by countless hordes. 56 * - the original sliplogin for 4.2bsd, Doug Kingston the mover behind it. 57 * 58 * There are two forms of usage: 59 * 60 * "sliplogin" 61 * Invoked simply as "sliplogin", the program looks up the username 62 * in the file /etc/slip.hosts. 63 * If an entry is found, the line on fd0 is configured for SLIP operation 64 * as specified in the file. 65 * 66 * "sliplogin IPhostlogin </dev/ttyb" 67 * Invoked by root with a username, the name is looked up in the 68 * /etc/slip.hosts file and if found fd0 is configured as in case 1. 69 */ 70 71 #include <sys/param.h> 72 #include <sys/socket.h> 73 #include <sys/file.h> 74 #include <sys/stat.h> 75 #include <syslog.h> 76 #include <netdb.h> 77 78 #include <termios.h> 79 #include <sys/ioctl.h> 80 #include <net/slip.h> 81 #include <net/if.h> 82 83 #include <stdio.h> 84 #include <errno.h> 85 #include <ctype.h> 86 #include <paths.h> 87 #include <string.h> 88 #include <unistd.h> 89 #include <stdlib.h> 90 #include <signal.h> 91 #include "pathnames.h" 92 93 extern char **environ; 94 95 static char *restricted_environ[] = { 96 "PATH=" _PATH_STDPATH, 97 NULL 98 }; 99 100 int unit; 101 int slip_mode; 102 speed_t speed; 103 int uid; 104 int keepal; 105 int outfill; 106 int slunit; 107 char loginargs[BUFSIZ]; 108 char loginfile[MAXPATHLEN]; 109 char loginname[BUFSIZ]; 110 static char raddr[32]; /* remote address */ 111 char ifname[IFNAMSIZ]; /* interface name */ 112 static char pidfilename[MAXPATHLEN]; /* name of pid file */ 113 static char iffilename[MAXPATHLEN]; /* name of if file */ 114 static pid_t pid; /* our pid */ 115 116 char * 117 make_ipaddr(void) 118 { 119 static char address[20] =""; 120 struct hostent *he; 121 unsigned long ipaddr; 122 123 address[0] = '\0'; 124 if ((he = gethostbyname(raddr)) != NULL) { 125 ipaddr = ntohl(*(long *)he->h_addr_list[0]); 126 sprintf(address, "%lu.%lu.%lu.%lu", 127 ipaddr >> 24, 128 (ipaddr & 0x00ff0000) >> 16, 129 (ipaddr & 0x0000ff00) >> 8, 130 (ipaddr & 0x000000ff)); 131 } 132 133 return address; 134 } 135 136 struct slip_modes { 137 char *sm_name; 138 int sm_or_flag; 139 int sm_and_flag; 140 } modes[] = { 141 "normal", 0 , 0 , 142 "compress", IFF_LINK0, IFF_LINK2, 143 "noicmp", IFF_LINK1, 0 , 144 "autocomp", IFF_LINK2, IFF_LINK0, 145 }; 146 147 void 148 findid(name) 149 char *name; 150 { 151 FILE *fp; 152 static char slopt[5][16]; 153 static char laddr[16]; 154 static char mask[16]; 155 char slparmsfile[MAXPATHLEN]; 156 char user[16]; 157 char buf[128]; 158 int i, j, n; 159 160 environ = restricted_environ; /* minimal protection for system() */ 161 162 (void)strncpy(loginname, name, sizeof(loginname)-1); 163 loginname[sizeof(loginname)-1] = '\0'; 164 165 if ((fp = fopen(_PATH_ACCESS, "r")) == NULL) { 166 accfile_err: 167 syslog(LOG_ERR, "%s: %m\n", _PATH_ACCESS); 168 exit(1); 169 } 170 while (fgets(loginargs, sizeof(loginargs) - 1, fp)) { 171 if (ferror(fp)) 172 goto accfile_err; 173 if (loginargs[0] == '#' || isspace(loginargs[0])) 174 continue; 175 n = sscanf(loginargs, "%15s%*[ \t]%15s%*[ \t]%15s%*[ \t]%15s%*[ \t]%15s%*[ \t]%15s%*[ \t]%15s%*[ \t]%15s%*[ \t]%15s\n", 176 user, laddr, raddr, mask, slopt[0], slopt[1], 177 slopt[2], slopt[3], slopt[4]); 178 if (n < 4) { 179 syslog(LOG_ERR, "%s: wrong format\n", _PATH_ACCESS); 180 exit(1); 181 } 182 if (strcmp(user, name) != 0) 183 continue; 184 185 (void) fclose(fp); 186 187 slip_mode = 0; 188 for (i = 0; i < n - 4; i++) { 189 for (j = 0; j < sizeof(modes)/sizeof(struct slip_modes); 190 j++) { 191 if (strcmp(modes[j].sm_name, slopt[i]) == 0) { 192 slip_mode |= (modes[j].sm_or_flag); 193 slip_mode &= ~(modes[j].sm_and_flag); 194 break; 195 } 196 } 197 } 198 199 /* 200 * we've found the guy we're looking for -- see if 201 * there's a login file we can use. First check for 202 * one specific to this host. If none found, try for 203 * a generic one. 204 */ 205 (void)snprintf(loginfile, sizeof(loginfile), "%s.%s", _PATH_LOGIN, name); 206 if (access(loginfile, R_OK|X_OK) != 0) { 207 (void)strncpy(loginfile, _PATH_LOGIN, sizeof(loginfile)-1); 208 loginfile[sizeof(loginfile)-1] = '\0'; 209 if (access(loginfile, R_OK|X_OK)) { 210 syslog(LOG_ERR, 211 "access denied for %s - no %s\n", 212 name, _PATH_LOGIN); 213 exit(5); 214 } 215 } 216 (void)snprintf(slparmsfile, sizeof(slparmsfile), "%s.%s", _PATH_SLPARMS, name); 217 if (access(slparmsfile, R_OK|X_OK) != 0) { 218 (void)strncpy(slparmsfile, _PATH_SLPARMS, sizeof(slparmsfile)-1); 219 slparmsfile[sizeof(slparmsfile)-1] = '\0'; 220 if (access(slparmsfile, R_OK|X_OK)) 221 *slparmsfile = '\0'; 222 } 223 keepal = outfill = 0; 224 slunit = -1; 225 if (*slparmsfile) { 226 if ((fp = fopen(slparmsfile, "r")) == NULL) { 227 slfile_err: 228 syslog(LOG_ERR, "%s: %m\n", slparmsfile); 229 exit(1); 230 } 231 n = 0; 232 while (fgets(buf, sizeof(buf) - 1, fp) != NULL) { 233 if (ferror(fp)) 234 goto slfile_err; 235 if (buf[0] == '#' || isspace(buf[0])) 236 continue; 237 n = sscanf(buf, "%d %d %d", &keepal, &outfill, &slunit); 238 if (n < 1) { 239 slwrong_fmt: 240 syslog(LOG_ERR, "%s: wrong format\n", slparmsfile); 241 exit(1); 242 } 243 (void) fclose(fp); 244 break; 245 } 246 if (n == 0) 247 goto slwrong_fmt; 248 } 249 250 return; 251 } 252 syslog(LOG_ERR, "SLIP access denied for %s\n", name); 253 exit(4); 254 /* NOTREACHED */ 255 } 256 257 char * 258 sigstr(s) 259 int s; 260 { 261 static char buf[32]; 262 263 switch (s) { 264 case SIGHUP: return("HUP"); 265 case SIGINT: return("INT"); 266 case SIGQUIT: return("QUIT"); 267 case SIGILL: return("ILL"); 268 case SIGTRAP: return("TRAP"); 269 case SIGIOT: return("IOT"); 270 case SIGEMT: return("EMT"); 271 case SIGFPE: return("FPE"); 272 case SIGKILL: return("KILL"); 273 case SIGBUS: return("BUS"); 274 case SIGSEGV: return("SEGV"); 275 case SIGSYS: return("SYS"); 276 case SIGPIPE: return("PIPE"); 277 case SIGALRM: return("ALRM"); 278 case SIGTERM: return("TERM"); 279 case SIGURG: return("URG"); 280 case SIGSTOP: return("STOP"); 281 case SIGTSTP: return("TSTP"); 282 case SIGCONT: return("CONT"); 283 case SIGCHLD: return("CHLD"); 284 case SIGTTIN: return("TTIN"); 285 case SIGTTOU: return("TTOU"); 286 case SIGIO: return("IO"); 287 case SIGXCPU: return("XCPU"); 288 case SIGXFSZ: return("XFSZ"); 289 case SIGVTALRM: return("VTALRM"); 290 case SIGPROF: return("PROF"); 291 case SIGWINCH: return("WINCH"); 292 #ifdef SIGLOST 293 case SIGLOST: return("LOST"); 294 #endif 295 case SIGUSR1: return("USR1"); 296 case SIGUSR2: return("USR2"); 297 } 298 (void)snprintf(buf, sizeof(buf), "sig %d", s); 299 return(buf); 300 } 301 302 void 303 hup_handler(s) 304 int s; 305 { 306 char logoutfile[MAXPATHLEN]; 307 308 (void) close(0); 309 seteuid(0); 310 (void)snprintf(logoutfile, sizeof(logoutfile), "%s.%s", _PATH_LOGOUT, loginname); 311 if (access(logoutfile, R_OK|X_OK) != 0) { 312 (void)strncpy(logoutfile, _PATH_LOGOUT, sizeof(logoutfile)-1); 313 logoutfile[sizeof(logoutfile)-1] = '\0'; 314 } 315 if (access(logoutfile, R_OK|X_OK) == 0) { 316 char logincmd[2*MAXPATHLEN+32]; 317 318 (void) snprintf(logincmd, sizeof(logincmd), "%s %d %ld %s", logoutfile, unit, speed, loginargs); 319 (void) system(logincmd); 320 } 321 syslog(LOG_INFO, "closed %s slip unit %d (%s)\n", loginname, unit, 322 sigstr(s)); 323 if (unlink(pidfilename) < 0 && errno != ENOENT) 324 syslog(LOG_WARNING, "unable to delete pid file: %m"); 325 if (unlink(iffilename) < 0 && errno != ENOENT) 326 syslog(LOG_WARNING, "unable to delete if file: %m"); 327 exit(1); 328 /* NOTREACHED */ 329 } 330 331 332 /* Modify the slip line mode and add any compression or no-icmp flags. */ 333 void line_flags(unit) 334 int unit; 335 { 336 struct ifreq ifr; 337 int s; 338 339 /* open a socket as the handle to the interface */ 340 s = socket(AF_INET, SOCK_DGRAM, 0); 341 if (s < 0) { 342 syslog(LOG_ERR, "socket: %m"); 343 exit(1); 344 } 345 sprintf(ifr.ifr_name, "sl%d", unit); 346 347 /* get the flags for the interface */ 348 if (ioctl(s, SIOCGIFFLAGS, (caddr_t)&ifr) < 0) { 349 syslog(LOG_ERR, "ioctl (SIOCGIFFLAGS): %m"); 350 exit(1); 351 } 352 353 /* Assert any compression or no-icmp flags. */ 354 #define SLMASK (~(IFF_LINK0 | IFF_LINK1 | IFF_LINK2)) 355 ifr.ifr_flags &= SLMASK; 356 ifr.ifr_flags |= slip_mode; 357 if (ioctl(s, SIOCSIFFLAGS, (caddr_t)&ifr) < 0) { 358 syslog(LOG_ERR, "ioctl (SIOCSIFFLAGS): %m"); 359 exit(1); 360 } 361 close(s); 362 } 363 364 365 main(argc, argv) 366 int argc; 367 char *argv[]; 368 { 369 int fd, s, ldisc; 370 char *name; 371 struct termios tios, otios; 372 char logincmd[2*BUFSIZ+32]; 373 extern uid_t getuid(); 374 375 FILE *pidfile; /* pid file */ 376 FILE *iffile; /* interfaces file */ 377 char *p; 378 int n; 379 char devnam[MAXPATHLEN] = _PATH_TTY; /* Device name */ 380 381 if ((name = strrchr(argv[0], '/')) == NULL) 382 name = argv[0]; 383 s = getdtablesize(); 384 for (fd = 3 ; fd < s ; fd++) 385 (void) close(fd); 386 openlog(name, LOG_PID|LOG_PERROR, LOG_DAEMON); 387 uid = getuid(); 388 if (argc > 1) { 389 findid(argv[1]); 390 391 /* 392 * Disassociate from current controlling terminal, if any, 393 * and ensure that the slip line is our controlling terminal. 394 */ 395 if (daemon(1, 1)) { 396 syslog(LOG_ERR, "daemon(1, 1): %m"); 397 exit(1); 398 } 399 if (argc > 2) { 400 if ((fd = open(argv[2], O_RDWR)) == -1) { 401 syslog(LOG_ERR, "open %s: %m", argv[2]); 402 exit(2); 403 } 404 (void) dup2(fd, 0); 405 if (fd > 2) 406 close(fd); 407 } 408 if (ioctl(0, TIOCSCTTY, 0) == -1) { 409 syslog(LOG_ERR, "ioctl (TIOCSCTTY): %m"); 410 exit(1); 411 } 412 if (tcsetpgrp(0, getpid()) < 0) { 413 syslog(LOG_ERR, "tcsetpgrp failed: %m"); 414 exit(1); 415 } 416 } else { 417 if ((name = getlogin()) == NULL) { 418 syslog(LOG_ERR, "access denied - login name not found\n"); 419 exit(1); 420 } 421 findid(name); 422 } 423 (void) fchmod(0, 0600); 424 (void) fprintf(stderr, "starting slip login for %s\n", loginname); 425 (void) fprintf(stderr, "your address is %s\n\n", make_ipaddr()); 426 427 (void) fflush(stderr); 428 sleep(1); 429 430 /* set up the line parameters */ 431 if (tcgetattr(0, &tios) < 0) { 432 syslog(LOG_ERR, "tcgetattr: %m"); 433 exit(1); 434 } 435 otios = tios; 436 cfmakeraw(&tios); 437 if (tcsetattr(0, TCSAFLUSH, &tios) < 0) { 438 syslog(LOG_ERR, "tcsetattr: %m"); 439 exit(1); 440 } 441 speed = cfgetispeed(&tios); 442 443 ldisc = SLIPDISC; 444 if (ioctl(0, TIOCSETD, &ldisc) < 0) { 445 syslog(LOG_ERR, "ioctl(TIOCSETD): %m"); 446 exit(1); 447 } 448 if (slunit >= 0 && ioctl(0, SLIOCSUNIT, &slunit) < 0) { 449 syslog(LOG_ERR, "ioctl (SLIOCSUNIT): %m"); 450 exit(1); 451 } 452 /* find out what unit number we were assigned */ 453 if (ioctl(0, SLIOCGUNIT, &unit) < 0) { 454 syslog(LOG_ERR, "ioctl (SLIOCGUNIT): %m"); 455 exit(1); 456 } 457 (void) signal(SIGHUP, hup_handler); 458 (void) signal(SIGTERM, hup_handler); 459 460 if (keepal > 0) { 461 (void) signal(SIGURG, hup_handler); 462 if (ioctl(0, SLIOCSKEEPAL, &keepal) < 0) { 463 syslog(LOG_ERR, "ioctl(SLIOCSKEEPAL): %m"); 464 exit(1); 465 } 466 } 467 if (outfill > 0 && ioctl(0, SLIOCSOUTFILL, &outfill) < 0) { 468 syslog(LOG_ERR, "ioctl(SLIOCSOUTFILL): %m"); 469 exit(1); 470 } 471 472 /* write pid to file */ 473 pid = getpid(); 474 (void) sprintf(ifname, "sl%d", unit); 475 (void) sprintf(pidfilename, "%s%s.pid", _PATH_VARRUN, ifname); 476 if ((pidfile = fopen(pidfilename, "w")) != NULL) { 477 fprintf(pidfile, "%d\n", pid); 478 (void) fclose(pidfile); 479 } else { 480 syslog(LOG_ERR, "Failed to create pid file %s: %m", 481 pidfilename); 482 pidfilename[0] = 0; 483 } 484 485 /* write interface unit number to file */ 486 p = ttyname(0); 487 if (p) 488 strcpy(devnam, p); 489 for (n = strlen(devnam); n > 0; n--) 490 if (devnam[n] == '/') { 491 n++; 492 break; 493 } 494 (void) sprintf(iffilename, "%s%s.if", _PATH_VARRUN, &devnam[n]); 495 if ((iffile = fopen(iffilename, "w")) != NULL) { 496 fprintf(iffile, "sl%d\n", unit); 497 (void) fclose(iffile); 498 } else { 499 syslog(LOG_ERR, "Failed to create if file %s: %m", iffilename); 500 iffilename[0] = 0; 501 } 502 503 504 syslog(LOG_INFO, "attaching slip unit %d for %s\n", unit, loginname); 505 (void)snprintf(logincmd, sizeof(logincmd), "%s %d %ld %s", loginfile, unit, speed, 506 loginargs); 507 /* 508 * aim stdout and errout at /dev/null so logincmd output won't 509 * babble into the slip tty line. 510 */ 511 (void) close(1); 512 if ((fd = open(_PATH_DEVNULL, O_WRONLY)) != 1) { 513 if (fd < 0) { 514 syslog(LOG_ERR, "open %s: %m", _PATH_DEVNULL); 515 exit(1); 516 } 517 (void) dup2(fd, 1); 518 (void) close(fd); 519 } 520 (void) dup2(1, 2); 521 522 /* 523 * Run login and logout scripts as root (real and effective); 524 * current route(8) is setuid root, and checks the real uid 525 * to see whether changes are allowed (or just "route get"). 526 */ 527 (void) setuid(0); 528 if (s = system(logincmd)) { 529 syslog(LOG_ERR, "%s login failed: exit status %d from %s", 530 loginname, s, loginfile); 531 exit(6); 532 } 533 534 /* Handle any compression or no-icmp flags. */ 535 line_flags(unit); 536 537 /* reset uid to users' to allow the user to give a signal. */ 538 seteuid(uid); 539 /* twiddle thumbs until we get a signal */ 540 while (1) 541 sigpause(0); 542 543 /* NOTREACHED */ 544 } 545