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 1.5 2008/09/14 22:04:36 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(char *name) 143 { 144 FILE *fp; 145 static char slopt[5][16]; 146 static char laddr[16]; 147 static char mask[16]; 148 char slparmsfile[MAXPATHLEN]; 149 char user[16]; 150 char buf[128]; 151 int i, j, n; 152 153 environ = restricted_environ; /* minimal protection for system() */ 154 155 strncpy(loginname, name, sizeof(loginname)-1); 156 loginname[sizeof(loginname)-1] = '\0'; 157 158 if ((fp = fopen(_PATH_ACCESS, "r")) == NULL) { 159 accfile_err: 160 syslog(LOG_ERR, "%s: %m\n", _PATH_ACCESS); 161 exit(1); 162 } 163 while (fgets(loginargs, sizeof(loginargs) - 1, fp)) { 164 if (ferror(fp)) 165 goto accfile_err; 166 if (loginargs[0] == '#' || isspace(loginargs[0])) 167 continue; 168 n = sscanf(loginargs, "%15s%*[ \t]%15s%*[ \t]%15s%*[ \t]%15s%*[ \t]%15s%*[ \t]%15s%*[ \t]%15s%*[ \t]%15s%*[ \t]%15s\n", 169 user, laddr, raddr, mask, slopt[0], slopt[1], 170 slopt[2], slopt[3], slopt[4]); 171 if (n < 4) { 172 syslog(LOG_ERR, "%s: wrong format\n", _PATH_ACCESS); 173 exit(1); 174 } 175 if (strcmp(user, name) != 0) 176 continue; 177 178 fclose(fp); 179 180 slip_mode = 0; 181 for (i = 0; i < n - 4; i++) { 182 for (j = 0; j < sizeof(modes)/sizeof(struct slip_modes); 183 j++) { 184 if (strcmp(modes[j].sm_name, slopt[i]) == 0) { 185 slip_mode |= (modes[j].sm_or_flag); 186 slip_mode &= ~(modes[j].sm_and_flag); 187 break; 188 } 189 } 190 } 191 192 /* 193 * we've found the guy we're looking for -- see if 194 * there's a login file we can use. First check for 195 * one specific to this host. If none found, try for 196 * a generic one. 197 */ 198 snprintf(loginfile, sizeof(loginfile), "%s.%s", _PATH_SLOGIN, name); 199 if (access(loginfile, R_OK|X_OK) != 0) { 200 strncpy(loginfile, _PATH_SLOGIN, sizeof(loginfile)-1); 201 loginfile[sizeof(loginfile)-1] = '\0'; 202 if (access(loginfile, R_OK|X_OK)) { 203 syslog(LOG_ERR, 204 "access denied for %s - no %s\n", 205 name, _PATH_SLOGIN); 206 exit(5); 207 } 208 } 209 snprintf(slparmsfile, sizeof(slparmsfile), "%s.%s", _PATH_SLPARMS, name); 210 if (access(slparmsfile, R_OK|X_OK) != 0) { 211 strncpy(slparmsfile, _PATH_SLPARMS, sizeof(slparmsfile)-1); 212 slparmsfile[sizeof(slparmsfile)-1] = '\0'; 213 if (access(slparmsfile, R_OK|X_OK)) 214 *slparmsfile = '\0'; 215 } 216 keepal = outfill = 0; 217 slunit = -1; 218 if (*slparmsfile) { 219 if ((fp = fopen(slparmsfile, "r")) == NULL) { 220 slfile_err: 221 syslog(LOG_ERR, "%s: %m\n", slparmsfile); 222 exit(1); 223 } 224 n = 0; 225 while (fgets(buf, sizeof(buf) - 1, fp) != NULL) { 226 if (ferror(fp)) 227 goto slfile_err; 228 if (buf[0] == '#' || isspace(buf[0])) 229 continue; 230 n = sscanf(buf, "%d %d %d", &keepal, &outfill, &slunit); 231 if (n < 1) { 232 slwrong_fmt: 233 syslog(LOG_ERR, "%s: wrong format\n", slparmsfile); 234 exit(1); 235 } 236 fclose(fp); 237 break; 238 } 239 if (n == 0) 240 goto slwrong_fmt; 241 } 242 243 return; 244 } 245 syslog(LOG_ERR, "SLIP access denied for %s\n", name); 246 exit(4); 247 /* NOTREACHED */ 248 } 249 250 char * 251 sigstr(int s) 252 { 253 static char buf[32]; 254 255 switch (s) { 256 case SIGHUP: return("HUP"); 257 case SIGINT: return("INT"); 258 case SIGQUIT: return("QUIT"); 259 case SIGILL: return("ILL"); 260 case SIGTRAP: return("TRAP"); 261 case SIGIOT: return("IOT"); 262 case SIGEMT: return("EMT"); 263 case SIGFPE: return("FPE"); 264 case SIGKILL: return("KILL"); 265 case SIGBUS: return("BUS"); 266 case SIGSEGV: return("SEGV"); 267 case SIGSYS: return("SYS"); 268 case SIGPIPE: return("PIPE"); 269 case SIGALRM: return("ALRM"); 270 case SIGTERM: return("TERM"); 271 case SIGURG: return("URG"); 272 case SIGSTOP: return("STOP"); 273 case SIGTSTP: return("TSTP"); 274 case SIGCONT: return("CONT"); 275 case SIGCHLD: return("CHLD"); 276 case SIGTTIN: return("TTIN"); 277 case SIGTTOU: return("TTOU"); 278 case SIGIO: return("IO"); 279 case SIGXCPU: return("XCPU"); 280 case SIGXFSZ: return("XFSZ"); 281 case SIGVTALRM: return("VTALRM"); 282 case SIGPROF: return("PROF"); 283 case SIGWINCH: return("WINCH"); 284 #ifdef SIGLOST 285 case SIGLOST: return("LOST"); 286 #endif 287 case SIGUSR1: return("USR1"); 288 case SIGUSR2: return("USR2"); 289 } 290 snprintf(buf, sizeof(buf), "sig %d", s); 291 return(buf); 292 } 293 294 void 295 hup_handler(int s) 296 { 297 char logoutfile[MAXPATHLEN]; 298 299 close(0); 300 seteuid(0); 301 snprintf(logoutfile, sizeof(logoutfile), "%s.%s", _PATH_SLOGOUT, loginname); 302 if (access(logoutfile, R_OK|X_OK) != 0) { 303 strncpy(logoutfile, _PATH_SLOGOUT, sizeof(logoutfile)-1); 304 logoutfile[sizeof(logoutfile)-1] = '\0'; 305 } 306 if (access(logoutfile, R_OK|X_OK) == 0) { 307 char logincmd[2*MAXPATHLEN+32]; 308 309 snprintf(logincmd, sizeof(logincmd), "%s %d %ld %s", logoutfile, unit, speed, loginargs); 310 system(logincmd); 311 } 312 syslog(LOG_INFO, "closed %s slip unit %d (%s)\n", loginname, unit, 313 sigstr(s)); 314 if (unlink(pidfilename) < 0 && errno != ENOENT) 315 syslog(LOG_WARNING, "unable to delete pid file: %m"); 316 if (unlink(iffilename) < 0 && errno != ENOENT) 317 syslog(LOG_WARNING, "unable to delete if file: %m"); 318 exit(1); 319 /* NOTREACHED */ 320 } 321 322 323 /* Modify the slip line mode and add any compression or no-icmp flags. */ 324 void 325 line_flags(int unit) 326 { 327 struct ifreq ifr; 328 int s; 329 330 /* open a socket as the handle to the interface */ 331 s = socket(AF_INET, SOCK_DGRAM, 0); 332 if (s < 0) { 333 syslog(LOG_ERR, "socket: %m"); 334 exit(1); 335 } 336 sprintf(ifr.ifr_name, "sl%d", unit); 337 338 /* get the flags for the interface */ 339 if (ioctl(s, SIOCGIFFLAGS, (caddr_t)&ifr) < 0) { 340 syslog(LOG_ERR, "ioctl (SIOCGIFFLAGS): %m"); 341 exit(1); 342 } 343 344 /* Assert any compression or no-icmp flags. */ 345 #define SLMASK (~(IFF_LINK0 | IFF_LINK1 | IFF_LINK2)) 346 ifr.ifr_flags &= SLMASK; 347 ifr.ifr_flags |= slip_mode; 348 if (ioctl(s, SIOCSIFFLAGS, (caddr_t)&ifr) < 0) { 349 syslog(LOG_ERR, "ioctl (SIOCSIFFLAGS): %m"); 350 exit(1); 351 } 352 close(s); 353 } 354 355 int 356 main(int argc, char *argv[]) 357 { 358 int fd, s, ldisc; 359 char *name; 360 struct termios tios, otios; 361 char logincmd[2*BUFSIZ+32]; 362 extern uid_t getuid(); 363 364 FILE *pidfile; /* pid file */ 365 FILE *iffile; /* interfaces file */ 366 char *p; 367 int n; 368 char devnam[MAXPATHLEN] = _PATH_TTY; /* Device name */ 369 370 if ((name = strrchr(argv[0], '/')) == NULL) 371 name = argv[0]; 372 s = getdtablesize(); 373 for (fd = 3 ; fd < s ; fd++) 374 close(fd); 375 openlog(name, LOG_PID|LOG_PERROR, LOG_DAEMON); 376 uid = getuid(); 377 if (argc > 1) { 378 findid(argv[1]); 379 380 /* 381 * Disassociate from current controlling terminal, if any, 382 * and ensure that the slip line is our controlling terminal. 383 */ 384 if (daemon(1, 1)) { 385 syslog(LOG_ERR, "daemon(1, 1): %m"); 386 exit(1); 387 } 388 if (argc > 2) { 389 if ((fd = open(argv[2], O_RDWR)) == -1) { 390 syslog(LOG_ERR, "open %s: %m", argv[2]); 391 exit(2); 392 } 393 dup2(fd, 0); 394 if (fd > 2) 395 close(fd); 396 } 397 if (ioctl(0, TIOCSCTTY, 0) == -1) { 398 syslog(LOG_ERR, "ioctl (TIOCSCTTY): %m"); 399 exit(1); 400 } 401 if (tcsetpgrp(0, getpid()) < 0) { 402 syslog(LOG_ERR, "tcsetpgrp failed: %m"); 403 exit(1); 404 } 405 } else { 406 if ((name = getlogin()) == NULL) { 407 syslog(LOG_ERR, "access denied - login name not found\n"); 408 exit(1); 409 } 410 findid(name); 411 } 412 fchmod(0, 0600); 413 fprintf(stderr, "starting slip login for %s\n", loginname); 414 fprintf(stderr, "your address is %s\n\n", make_ipaddr()); 415 416 fflush(stderr); 417 sleep(1); 418 419 /* set up the line parameters */ 420 if (tcgetattr(0, &tios) < 0) { 421 syslog(LOG_ERR, "tcgetattr: %m"); 422 exit(1); 423 } 424 otios = tios; 425 cfmakeraw(&tios); 426 if (tcsetattr(0, TCSAFLUSH, &tios) < 0) { 427 syslog(LOG_ERR, "tcsetattr: %m"); 428 exit(1); 429 } 430 speed = cfgetispeed(&tios); 431 432 ldisc = SLIPDISC; 433 if (ioctl(0, TIOCSETD, &ldisc) < 0) { 434 syslog(LOG_ERR, "ioctl(TIOCSETD): %m"); 435 exit(1); 436 } 437 if (slunit >= 0 && ioctl(0, SLIOCSUNIT, &slunit) < 0) { 438 syslog(LOG_ERR, "ioctl (SLIOCSUNIT): %m"); 439 exit(1); 440 } 441 /* find out what unit number we were assigned */ 442 if (ioctl(0, SLIOCGUNIT, &unit) < 0) { 443 syslog(LOG_ERR, "ioctl (SLIOCGUNIT): %m"); 444 exit(1); 445 } 446 signal(SIGHUP, hup_handler); 447 signal(SIGTERM, hup_handler); 448 449 if (keepal > 0) { 450 signal(SIGURG, hup_handler); 451 if (ioctl(0, SLIOCSKEEPAL, &keepal) < 0) { 452 syslog(LOG_ERR, "ioctl(SLIOCSKEEPAL): %m"); 453 exit(1); 454 } 455 } 456 if (outfill > 0 && ioctl(0, SLIOCSOUTFILL, &outfill) < 0) { 457 syslog(LOG_ERR, "ioctl(SLIOCSOUTFILL): %m"); 458 exit(1); 459 } 460 461 /* write pid to file */ 462 pid = getpid(); 463 sprintf(ifname, "sl%d", unit); 464 sprintf(pidfilename, "%s%s.pid", _PATH_VARRUN, ifname); 465 if ((pidfile = fopen(pidfilename, "w")) != NULL) { 466 fprintf(pidfile, "%d\n", pid); 467 fclose(pidfile); 468 } else { 469 syslog(LOG_ERR, "Failed to create pid file %s: %m", 470 pidfilename); 471 pidfilename[0] = 0; 472 } 473 474 /* write interface unit number to file */ 475 p = ttyname(0); 476 if (p) 477 strcpy(devnam, p); 478 for (n = strlen(devnam); n > 0; n--) 479 if (devnam[n] == '/') { 480 n++; 481 break; 482 } 483 sprintf(iffilename, "%s%s.if", _PATH_VARRUN, &devnam[n]); 484 if ((iffile = fopen(iffilename, "w")) != NULL) { 485 fprintf(iffile, "sl%d\n", unit); 486 fclose(iffile); 487 } else { 488 syslog(LOG_ERR, "Failed to create if file %s: %m", iffilename); 489 iffilename[0] = 0; 490 } 491 492 493 syslog(LOG_INFO, "attaching slip unit %d for %s\n", unit, loginname); 494 snprintf(logincmd, sizeof(logincmd), "%s %d %ld %s", loginfile, unit, speed, 495 loginargs); 496 /* 497 * aim stdout and errout at /dev/null so logincmd output won't 498 * babble into the slip tty line. 499 */ 500 close(1); 501 if ((fd = open(_PATH_DEVNULL, O_WRONLY)) != 1) { 502 if (fd < 0) { 503 syslog(LOG_ERR, "open %s: %m", _PATH_DEVNULL); 504 exit(1); 505 } 506 dup2(fd, 1); 507 close(fd); 508 } 509 dup2(1, 2); 510 511 /* 512 * Run login and logout scripts as root (real and effective); 513 * current route(8) is setuid root, and checks the real uid 514 * to see whether changes are allowed (or just "route get"). 515 */ 516 setuid(0); 517 if (s = system(logincmd)) { 518 syslog(LOG_ERR, "%s login failed: exit status %d from %s", 519 loginname, s, loginfile); 520 exit(6); 521 } 522 523 /* Handle any compression or no-icmp flags. */ 524 line_flags(unit); 525 526 /* reset uid to users' to allow the user to give a signal. */ 527 seteuid(uid); 528 /* twiddle thumbs until we get a signal */ 529 while (1) 530 sigpause(0); 531 532 /* NOTREACHED */ 533 } 534