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 * @(#) Copyright (c) 1990, 1993 The Regents of the University of California. All rights reserved. 34 * @(#)sliplogin.c 8.2 (Berkeley) 2/1/94 35 * $FreeBSD: src/usr.sbin/sliplogin/sliplogin.c,v 1.9.6.2 2001/07/19 05:21:28 kris Exp $ 36 * $DragonFly: src/usr.sbin/sliplogin/sliplogin.c,v 1.3 2004/12/18 22:48:14 swildner Exp $ 37 */ 38 39 /* 40 * sliplogin.c 41 * [MUST BE RUN SUID, SLOPEN DOES A SUSER()!] 42 * 43 * This program initializes its own tty port to be an async TCP/IP interface. 44 * It sets the line discipline to slip, invokes a shell script to initialize 45 * the network interface, then pauses forever waiting for hangup. 46 * 47 * It is a remote descendant of several similar programs with incestuous ties: 48 * - Kirk Smith's slipconf, modified by Richard Johnsson @ DEC WRL. 49 * - slattach, probably by Rick Adams but touched by countless hordes. 50 * - the original sliplogin for 4.2bsd, Doug Kingston the mover behind it. 51 * 52 * There are two forms of usage: 53 * 54 * "sliplogin" 55 * Invoked simply as "sliplogin", the program looks up the username 56 * in the file /etc/slip.hosts. 57 * If an entry is found, the line on fd0 is configured for SLIP operation 58 * as specified in the file. 59 * 60 * "sliplogin IPhostlogin </dev/ttyb" 61 * Invoked by root with a username, the name is looked up in the 62 * /etc/slip.hosts file and if found fd0 is configured as in case 1. 63 */ 64 65 #include <sys/param.h> 66 #include <sys/socket.h> 67 #include <sys/file.h> 68 #include <sys/stat.h> 69 #include <syslog.h> 70 #include <netdb.h> 71 72 #include <termios.h> 73 #include <sys/ioctl.h> 74 #include <net/slip.h> 75 #include <net/if.h> 76 77 #include <stdio.h> 78 #include <errno.h> 79 #include <ctype.h> 80 #include <paths.h> 81 #include <string.h> 82 #include <unistd.h> 83 #include <stdlib.h> 84 #include <signal.h> 85 #include "pathnames.h" 86 87 extern char **environ; 88 89 static char *restricted_environ[] = { 90 "PATH=" _PATH_STDPATH, 91 NULL 92 }; 93 94 int unit; 95 int slip_mode; 96 speed_t speed; 97 int uid; 98 int keepal; 99 int outfill; 100 int slunit; 101 char loginargs[BUFSIZ]; 102 char loginfile[MAXPATHLEN]; 103 char loginname[BUFSIZ]; 104 static char raddr[32]; /* remote address */ 105 char ifname[IFNAMSIZ]; /* interface name */ 106 static char pidfilename[MAXPATHLEN]; /* name of pid file */ 107 static char iffilename[MAXPATHLEN]; /* name of if file */ 108 static pid_t pid; /* our pid */ 109 110 char * 111 make_ipaddr(void) 112 { 113 static char address[20] =""; 114 struct hostent *he; 115 unsigned long ipaddr; 116 117 address[0] = '\0'; 118 if ((he = gethostbyname(raddr)) != NULL) { 119 ipaddr = ntohl(*(long *)he->h_addr_list[0]); 120 sprintf(address, "%lu.%lu.%lu.%lu", 121 ipaddr >> 24, 122 (ipaddr & 0x00ff0000) >> 16, 123 (ipaddr & 0x0000ff00) >> 8, 124 (ipaddr & 0x000000ff)); 125 } 126 127 return address; 128 } 129 130 struct slip_modes { 131 char *sm_name; 132 int sm_or_flag; 133 int sm_and_flag; 134 } modes[] = { 135 "normal", 0 , 0 , 136 "compress", IFF_LINK0, IFF_LINK2, 137 "noicmp", IFF_LINK1, 0 , 138 "autocomp", IFF_LINK2, IFF_LINK0, 139 }; 140 141 void 142 findid(name) 143 char *name; 144 { 145 FILE *fp; 146 static char slopt[5][16]; 147 static char laddr[16]; 148 static char mask[16]; 149 char slparmsfile[MAXPATHLEN]; 150 char user[16]; 151 char buf[128]; 152 int i, j, n; 153 154 environ = restricted_environ; /* minimal protection for system() */ 155 156 strncpy(loginname, name, sizeof(loginname)-1); 157 loginname[sizeof(loginname)-1] = '\0'; 158 159 if ((fp = fopen(_PATH_ACCESS, "r")) == NULL) { 160 accfile_err: 161 syslog(LOG_ERR, "%s: %m\n", _PATH_ACCESS); 162 exit(1); 163 } 164 while (fgets(loginargs, sizeof(loginargs) - 1, fp)) { 165 if (ferror(fp)) 166 goto accfile_err; 167 if (loginargs[0] == '#' || isspace(loginargs[0])) 168 continue; 169 n = sscanf(loginargs, "%15s%*[ \t]%15s%*[ \t]%15s%*[ \t]%15s%*[ \t]%15s%*[ \t]%15s%*[ \t]%15s%*[ \t]%15s%*[ \t]%15s\n", 170 user, laddr, raddr, mask, slopt[0], slopt[1], 171 slopt[2], slopt[3], slopt[4]); 172 if (n < 4) { 173 syslog(LOG_ERR, "%s: wrong format\n", _PATH_ACCESS); 174 exit(1); 175 } 176 if (strcmp(user, name) != 0) 177 continue; 178 179 fclose(fp); 180 181 slip_mode = 0; 182 for (i = 0; i < n - 4; i++) { 183 for (j = 0; j < sizeof(modes)/sizeof(struct slip_modes); 184 j++) { 185 if (strcmp(modes[j].sm_name, slopt[i]) == 0) { 186 slip_mode |= (modes[j].sm_or_flag); 187 slip_mode &= ~(modes[j].sm_and_flag); 188 break; 189 } 190 } 191 } 192 193 /* 194 * we've found the guy we're looking for -- see if 195 * there's a login file we can use. First check for 196 * one specific to this host. If none found, try for 197 * a generic one. 198 */ 199 snprintf(loginfile, sizeof(loginfile), "%s.%s", _PATH_LOGIN, name); 200 if (access(loginfile, R_OK|X_OK) != 0) { 201 strncpy(loginfile, _PATH_LOGIN, sizeof(loginfile)-1); 202 loginfile[sizeof(loginfile)-1] = '\0'; 203 if (access(loginfile, R_OK|X_OK)) { 204 syslog(LOG_ERR, 205 "access denied for %s - no %s\n", 206 name, _PATH_LOGIN); 207 exit(5); 208 } 209 } 210 snprintf(slparmsfile, sizeof(slparmsfile), "%s.%s", _PATH_SLPARMS, name); 211 if (access(slparmsfile, R_OK|X_OK) != 0) { 212 strncpy(slparmsfile, _PATH_SLPARMS, sizeof(slparmsfile)-1); 213 slparmsfile[sizeof(slparmsfile)-1] = '\0'; 214 if (access(slparmsfile, R_OK|X_OK)) 215 *slparmsfile = '\0'; 216 } 217 keepal = outfill = 0; 218 slunit = -1; 219 if (*slparmsfile) { 220 if ((fp = fopen(slparmsfile, "r")) == NULL) { 221 slfile_err: 222 syslog(LOG_ERR, "%s: %m\n", slparmsfile); 223 exit(1); 224 } 225 n = 0; 226 while (fgets(buf, sizeof(buf) - 1, fp) != NULL) { 227 if (ferror(fp)) 228 goto slfile_err; 229 if (buf[0] == '#' || isspace(buf[0])) 230 continue; 231 n = sscanf(buf, "%d %d %d", &keepal, &outfill, &slunit); 232 if (n < 1) { 233 slwrong_fmt: 234 syslog(LOG_ERR, "%s: wrong format\n", slparmsfile); 235 exit(1); 236 } 237 fclose(fp); 238 break; 239 } 240 if (n == 0) 241 goto slwrong_fmt; 242 } 243 244 return; 245 } 246 syslog(LOG_ERR, "SLIP access denied for %s\n", name); 247 exit(4); 248 /* NOTREACHED */ 249 } 250 251 char * 252 sigstr(s) 253 int s; 254 { 255 static char buf[32]; 256 257 switch (s) { 258 case SIGHUP: return("HUP"); 259 case SIGINT: return("INT"); 260 case SIGQUIT: return("QUIT"); 261 case SIGILL: return("ILL"); 262 case SIGTRAP: return("TRAP"); 263 case SIGIOT: return("IOT"); 264 case SIGEMT: return("EMT"); 265 case SIGFPE: return("FPE"); 266 case SIGKILL: return("KILL"); 267 case SIGBUS: return("BUS"); 268 case SIGSEGV: return("SEGV"); 269 case SIGSYS: return("SYS"); 270 case SIGPIPE: return("PIPE"); 271 case SIGALRM: return("ALRM"); 272 case SIGTERM: return("TERM"); 273 case SIGURG: return("URG"); 274 case SIGSTOP: return("STOP"); 275 case SIGTSTP: return("TSTP"); 276 case SIGCONT: return("CONT"); 277 case SIGCHLD: return("CHLD"); 278 case SIGTTIN: return("TTIN"); 279 case SIGTTOU: return("TTOU"); 280 case SIGIO: return("IO"); 281 case SIGXCPU: return("XCPU"); 282 case SIGXFSZ: return("XFSZ"); 283 case SIGVTALRM: return("VTALRM"); 284 case SIGPROF: return("PROF"); 285 case SIGWINCH: return("WINCH"); 286 #ifdef SIGLOST 287 case SIGLOST: return("LOST"); 288 #endif 289 case SIGUSR1: return("USR1"); 290 case SIGUSR2: return("USR2"); 291 } 292 snprintf(buf, sizeof(buf), "sig %d", s); 293 return(buf); 294 } 295 296 void 297 hup_handler(s) 298 int s; 299 { 300 char logoutfile[MAXPATHLEN]; 301 302 close(0); 303 seteuid(0); 304 snprintf(logoutfile, sizeof(logoutfile), "%s.%s", _PATH_LOGOUT, loginname); 305 if (access(logoutfile, R_OK|X_OK) != 0) { 306 strncpy(logoutfile, _PATH_LOGOUT, sizeof(logoutfile)-1); 307 logoutfile[sizeof(logoutfile)-1] = '\0'; 308 } 309 if (access(logoutfile, R_OK|X_OK) == 0) { 310 char logincmd[2*MAXPATHLEN+32]; 311 312 snprintf(logincmd, sizeof(logincmd), "%s %d %ld %s", logoutfile, unit, speed, loginargs); 313 system(logincmd); 314 } 315 syslog(LOG_INFO, "closed %s slip unit %d (%s)\n", loginname, unit, 316 sigstr(s)); 317 if (unlink(pidfilename) < 0 && errno != ENOENT) 318 syslog(LOG_WARNING, "unable to delete pid file: %m"); 319 if (unlink(iffilename) < 0 && errno != ENOENT) 320 syslog(LOG_WARNING, "unable to delete if file: %m"); 321 exit(1); 322 /* NOTREACHED */ 323 } 324 325 326 /* Modify the slip line mode and add any compression or no-icmp flags. */ 327 void line_flags(unit) 328 int unit; 329 { 330 struct ifreq ifr; 331 int s; 332 333 /* open a socket as the handle to the interface */ 334 s = socket(AF_INET, SOCK_DGRAM, 0); 335 if (s < 0) { 336 syslog(LOG_ERR, "socket: %m"); 337 exit(1); 338 } 339 sprintf(ifr.ifr_name, "sl%d", unit); 340 341 /* get the flags for the interface */ 342 if (ioctl(s, SIOCGIFFLAGS, (caddr_t)&ifr) < 0) { 343 syslog(LOG_ERR, "ioctl (SIOCGIFFLAGS): %m"); 344 exit(1); 345 } 346 347 /* Assert any compression or no-icmp flags. */ 348 #define SLMASK (~(IFF_LINK0 | IFF_LINK1 | IFF_LINK2)) 349 ifr.ifr_flags &= SLMASK; 350 ifr.ifr_flags |= slip_mode; 351 if (ioctl(s, SIOCSIFFLAGS, (caddr_t)&ifr) < 0) { 352 syslog(LOG_ERR, "ioctl (SIOCSIFFLAGS): %m"); 353 exit(1); 354 } 355 close(s); 356 } 357 358 359 main(argc, argv) 360 int argc; 361 char *argv[]; 362 { 363 int fd, s, ldisc; 364 char *name; 365 struct termios tios, otios; 366 char logincmd[2*BUFSIZ+32]; 367 extern uid_t getuid(); 368 369 FILE *pidfile; /* pid file */ 370 FILE *iffile; /* interfaces file */ 371 char *p; 372 int n; 373 char devnam[MAXPATHLEN] = _PATH_TTY; /* Device name */ 374 375 if ((name = strrchr(argv[0], '/')) == NULL) 376 name = argv[0]; 377 s = getdtablesize(); 378 for (fd = 3 ; fd < s ; fd++) 379 close(fd); 380 openlog(name, LOG_PID|LOG_PERROR, LOG_DAEMON); 381 uid = getuid(); 382 if (argc > 1) { 383 findid(argv[1]); 384 385 /* 386 * Disassociate from current controlling terminal, if any, 387 * and ensure that the slip line is our controlling terminal. 388 */ 389 if (daemon(1, 1)) { 390 syslog(LOG_ERR, "daemon(1, 1): %m"); 391 exit(1); 392 } 393 if (argc > 2) { 394 if ((fd = open(argv[2], O_RDWR)) == -1) { 395 syslog(LOG_ERR, "open %s: %m", argv[2]); 396 exit(2); 397 } 398 dup2(fd, 0); 399 if (fd > 2) 400 close(fd); 401 } 402 if (ioctl(0, TIOCSCTTY, 0) == -1) { 403 syslog(LOG_ERR, "ioctl (TIOCSCTTY): %m"); 404 exit(1); 405 } 406 if (tcsetpgrp(0, getpid()) < 0) { 407 syslog(LOG_ERR, "tcsetpgrp failed: %m"); 408 exit(1); 409 } 410 } else { 411 if ((name = getlogin()) == NULL) { 412 syslog(LOG_ERR, "access denied - login name not found\n"); 413 exit(1); 414 } 415 findid(name); 416 } 417 fchmod(0, 0600); 418 fprintf(stderr, "starting slip login for %s\n", loginname); 419 fprintf(stderr, "your address is %s\n\n", make_ipaddr()); 420 421 fflush(stderr); 422 sleep(1); 423 424 /* set up the line parameters */ 425 if (tcgetattr(0, &tios) < 0) { 426 syslog(LOG_ERR, "tcgetattr: %m"); 427 exit(1); 428 } 429 otios = tios; 430 cfmakeraw(&tios); 431 if (tcsetattr(0, TCSAFLUSH, &tios) < 0) { 432 syslog(LOG_ERR, "tcsetattr: %m"); 433 exit(1); 434 } 435 speed = cfgetispeed(&tios); 436 437 ldisc = SLIPDISC; 438 if (ioctl(0, TIOCSETD, &ldisc) < 0) { 439 syslog(LOG_ERR, "ioctl(TIOCSETD): %m"); 440 exit(1); 441 } 442 if (slunit >= 0 && ioctl(0, SLIOCSUNIT, &slunit) < 0) { 443 syslog(LOG_ERR, "ioctl (SLIOCSUNIT): %m"); 444 exit(1); 445 } 446 /* find out what unit number we were assigned */ 447 if (ioctl(0, SLIOCGUNIT, &unit) < 0) { 448 syslog(LOG_ERR, "ioctl (SLIOCGUNIT): %m"); 449 exit(1); 450 } 451 signal(SIGHUP, hup_handler); 452 signal(SIGTERM, hup_handler); 453 454 if (keepal > 0) { 455 signal(SIGURG, hup_handler); 456 if (ioctl(0, SLIOCSKEEPAL, &keepal) < 0) { 457 syslog(LOG_ERR, "ioctl(SLIOCSKEEPAL): %m"); 458 exit(1); 459 } 460 } 461 if (outfill > 0 && ioctl(0, SLIOCSOUTFILL, &outfill) < 0) { 462 syslog(LOG_ERR, "ioctl(SLIOCSOUTFILL): %m"); 463 exit(1); 464 } 465 466 /* write pid to file */ 467 pid = getpid(); 468 sprintf(ifname, "sl%d", unit); 469 sprintf(pidfilename, "%s%s.pid", _PATH_VARRUN, ifname); 470 if ((pidfile = fopen(pidfilename, "w")) != NULL) { 471 fprintf(pidfile, "%d\n", pid); 472 fclose(pidfile); 473 } else { 474 syslog(LOG_ERR, "Failed to create pid file %s: %m", 475 pidfilename); 476 pidfilename[0] = 0; 477 } 478 479 /* write interface unit number to file */ 480 p = ttyname(0); 481 if (p) 482 strcpy(devnam, p); 483 for (n = strlen(devnam); n > 0; n--) 484 if (devnam[n] == '/') { 485 n++; 486 break; 487 } 488 sprintf(iffilename, "%s%s.if", _PATH_VARRUN, &devnam[n]); 489 if ((iffile = fopen(iffilename, "w")) != NULL) { 490 fprintf(iffile, "sl%d\n", unit); 491 fclose(iffile); 492 } else { 493 syslog(LOG_ERR, "Failed to create if file %s: %m", iffilename); 494 iffilename[0] = 0; 495 } 496 497 498 syslog(LOG_INFO, "attaching slip unit %d for %s\n", unit, loginname); 499 snprintf(logincmd, sizeof(logincmd), "%s %d %ld %s", loginfile, unit, speed, 500 loginargs); 501 /* 502 * aim stdout and errout at /dev/null so logincmd output won't 503 * babble into the slip tty line. 504 */ 505 close(1); 506 if ((fd = open(_PATH_DEVNULL, O_WRONLY)) != 1) { 507 if (fd < 0) { 508 syslog(LOG_ERR, "open %s: %m", _PATH_DEVNULL); 509 exit(1); 510 } 511 dup2(fd, 1); 512 close(fd); 513 } 514 dup2(1, 2); 515 516 /* 517 * Run login and logout scripts as root (real and effective); 518 * current route(8) is setuid root, and checks the real uid 519 * to see whether changes are allowed (or just "route get"). 520 */ 521 setuid(0); 522 if (s = system(logincmd)) { 523 syslog(LOG_ERR, "%s login failed: exit status %d from %s", 524 loginname, s, loginfile); 525 exit(6); 526 } 527 528 /* Handle any compression or no-icmp flags. */ 529 line_flags(unit); 530 531 /* reset uid to users' to allow the user to give a signal. */ 532 seteuid(uid); 533 /* twiddle thumbs until we get a signal */ 534 while (1) 535 sigpause(0); 536 537 /* NOTREACHED */ 538 } 539