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. Neither the name of the University nor the names of its contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 * 29 * @(#) Copyright (c) 1990, 1993 The Regents of the University of California. All rights reserved. 30 * @(#)sliplogin.c 8.2 (Berkeley) 2/1/94 31 * $FreeBSD: src/usr.sbin/sliplogin/sliplogin.c,v 1.9.6.2 2001/07/19 05:21:28 kris Exp $ 32 * $DragonFly: src/usr.sbin/sliplogin/sliplogin.c,v 1.5 2008/09/14 22:04:36 swildner Exp $ 33 */ 34 35 /* 36 * sliplogin.c 37 * [MUST BE RUN SUID, SLOPEN DOES A SUSER()!] 38 * 39 * This program initializes its own tty port to be an async TCP/IP interface. 40 * It sets the line discipline to slip, invokes a shell script to initialize 41 * the network interface, then pauses forever waiting for hangup. 42 * 43 * It is a remote descendant of several similar programs with incestuous ties: 44 * - Kirk Smith's slipconf, modified by Richard Johnsson @ DEC WRL. 45 * - slattach, probably by Rick Adams but touched by countless hordes. 46 * - the original sliplogin for 4.2bsd, Doug Kingston the mover behind it. 47 * 48 * There are two forms of usage: 49 * 50 * "sliplogin" 51 * Invoked simply as "sliplogin", the program looks up the username 52 * in the file /etc/slip.hosts. 53 * If an entry is found, the line on fd0 is configured for SLIP operation 54 * as specified in the file. 55 * 56 * "sliplogin IPhostlogin </dev/ttyb" 57 * Invoked by root with a username, the name is looked up in the 58 * /etc/slip.hosts file and if found fd0 is configured as in case 1. 59 */ 60 61 #include <sys/param.h> 62 #include <sys/socket.h> 63 #include <sys/file.h> 64 #include <sys/stat.h> 65 #include <syslog.h> 66 #include <netdb.h> 67 68 #include <termios.h> 69 #include <sys/ioctl.h> 70 #include <net/slip.h> 71 #include <net/if.h> 72 73 #include <stdio.h> 74 #include <errno.h> 75 #include <ctype.h> 76 #include <paths.h> 77 #include <string.h> 78 #include <unistd.h> 79 #include <stdlib.h> 80 #include <signal.h> 81 #include "pathnames.h" 82 83 extern char **environ; 84 85 static char *restricted_environ[] = { 86 "PATH=" _PATH_STDPATH, 87 NULL 88 }; 89 90 int unit; 91 int slip_mode; 92 speed_t speed; 93 int uid; 94 int keepal; 95 int outfill; 96 int slunit; 97 char loginargs[BUFSIZ]; 98 char loginfile[MAXPATHLEN]; 99 char loginname[BUFSIZ]; 100 static char raddr[32]; /* remote address */ 101 char ifname[IFNAMSIZ]; /* interface name */ 102 static char pidfilename[MAXPATHLEN]; /* name of pid file */ 103 static char iffilename[MAXPATHLEN]; /* name of if file */ 104 static pid_t pid; /* our pid */ 105 106 char * 107 make_ipaddr(void) 108 { 109 static char address[20] =""; 110 struct hostent *he; 111 unsigned long ipaddr; 112 113 address[0] = '\0'; 114 if ((he = gethostbyname(raddr)) != NULL) { 115 ipaddr = ntohl(*(long *)he->h_addr_list[0]); 116 sprintf(address, "%lu.%lu.%lu.%lu", 117 ipaddr >> 24, 118 (ipaddr & 0x00ff0000) >> 16, 119 (ipaddr & 0x0000ff00) >> 8, 120 (ipaddr & 0x000000ff)); 121 } 122 123 return address; 124 } 125 126 struct slip_modes { 127 char *sm_name; 128 int sm_or_flag; 129 int sm_and_flag; 130 } modes[] = { 131 "normal", 0 , 0 , 132 "compress", IFF_LINK0, IFF_LINK2, 133 "noicmp", IFF_LINK1, 0 , 134 "autocomp", IFF_LINK2, IFF_LINK0, 135 }; 136 137 void 138 findid(char *name) 139 { 140 FILE *fp; 141 static char slopt[5][16]; 142 static char laddr[16]; 143 static char mask[16]; 144 char slparmsfile[MAXPATHLEN]; 145 char user[16]; 146 char buf[128]; 147 int i, j, n; 148 149 environ = restricted_environ; /* minimal protection for system() */ 150 151 strncpy(loginname, name, sizeof(loginname)-1); 152 loginname[sizeof(loginname)-1] = '\0'; 153 154 if ((fp = fopen(_PATH_ACCESS, "r")) == NULL) { 155 accfile_err: 156 syslog(LOG_ERR, "%s: %m\n", _PATH_ACCESS); 157 exit(1); 158 } 159 while (fgets(loginargs, sizeof(loginargs) - 1, fp)) { 160 if (ferror(fp)) 161 goto accfile_err; 162 if (loginargs[0] == '#' || isspace(loginargs[0])) 163 continue; 164 n = sscanf(loginargs, "%15s%*[ \t]%15s%*[ \t]%15s%*[ \t]%15s%*[ \t]%15s%*[ \t]%15s%*[ \t]%15s%*[ \t]%15s%*[ \t]%15s\n", 165 user, laddr, raddr, mask, slopt[0], slopt[1], 166 slopt[2], slopt[3], slopt[4]); 167 if (n < 4) { 168 syslog(LOG_ERR, "%s: wrong format\n", _PATH_ACCESS); 169 exit(1); 170 } 171 if (strcmp(user, name) != 0) 172 continue; 173 174 fclose(fp); 175 176 slip_mode = 0; 177 for (i = 0; i < n - 4; i++) { 178 for (j = 0; j < sizeof(modes)/sizeof(struct slip_modes); 179 j++) { 180 if (strcmp(modes[j].sm_name, slopt[i]) == 0) { 181 slip_mode |= (modes[j].sm_or_flag); 182 slip_mode &= ~(modes[j].sm_and_flag); 183 break; 184 } 185 } 186 } 187 188 /* 189 * we've found the guy we're looking for -- see if 190 * there's a login file we can use. First check for 191 * one specific to this host. If none found, try for 192 * a generic one. 193 */ 194 snprintf(loginfile, sizeof(loginfile), "%s.%s", _PATH_SLOGIN, name); 195 if (access(loginfile, R_OK|X_OK) != 0) { 196 strncpy(loginfile, _PATH_SLOGIN, sizeof(loginfile)-1); 197 loginfile[sizeof(loginfile)-1] = '\0'; 198 if (access(loginfile, R_OK|X_OK)) { 199 syslog(LOG_ERR, 200 "access denied for %s - no %s\n", 201 name, _PATH_SLOGIN); 202 exit(5); 203 } 204 } 205 snprintf(slparmsfile, sizeof(slparmsfile), "%s.%s", _PATH_SLPARMS, name); 206 if (access(slparmsfile, R_OK|X_OK) != 0) { 207 strncpy(slparmsfile, _PATH_SLPARMS, sizeof(slparmsfile)-1); 208 slparmsfile[sizeof(slparmsfile)-1] = '\0'; 209 if (access(slparmsfile, R_OK|X_OK)) 210 *slparmsfile = '\0'; 211 } 212 keepal = outfill = 0; 213 slunit = -1; 214 if (*slparmsfile) { 215 if ((fp = fopen(slparmsfile, "r")) == NULL) { 216 slfile_err: 217 syslog(LOG_ERR, "%s: %m\n", slparmsfile); 218 exit(1); 219 } 220 n = 0; 221 while (fgets(buf, sizeof(buf) - 1, fp) != NULL) { 222 if (ferror(fp)) 223 goto slfile_err; 224 if (buf[0] == '#' || isspace(buf[0])) 225 continue; 226 n = sscanf(buf, "%d %d %d", &keepal, &outfill, &slunit); 227 if (n < 1) { 228 slwrong_fmt: 229 syslog(LOG_ERR, "%s: wrong format\n", slparmsfile); 230 exit(1); 231 } 232 fclose(fp); 233 break; 234 } 235 if (n == 0) 236 goto slwrong_fmt; 237 } 238 239 return; 240 } 241 syslog(LOG_ERR, "SLIP access denied for %s\n", name); 242 exit(4); 243 /* NOTREACHED */ 244 } 245 246 char * 247 sigstr(int s) 248 { 249 static char buf[32]; 250 251 switch (s) { 252 case SIGHUP: return("HUP"); 253 case SIGINT: return("INT"); 254 case SIGQUIT: return("QUIT"); 255 case SIGILL: return("ILL"); 256 case SIGTRAP: return("TRAP"); 257 case SIGIOT: return("IOT"); 258 case SIGEMT: return("EMT"); 259 case SIGFPE: return("FPE"); 260 case SIGKILL: return("KILL"); 261 case SIGBUS: return("BUS"); 262 case SIGSEGV: return("SEGV"); 263 case SIGSYS: return("SYS"); 264 case SIGPIPE: return("PIPE"); 265 case SIGALRM: return("ALRM"); 266 case SIGTERM: return("TERM"); 267 case SIGURG: return("URG"); 268 case SIGSTOP: return("STOP"); 269 case SIGTSTP: return("TSTP"); 270 case SIGCONT: return("CONT"); 271 case SIGCHLD: return("CHLD"); 272 case SIGTTIN: return("TTIN"); 273 case SIGTTOU: return("TTOU"); 274 case SIGIO: return("IO"); 275 case SIGXCPU: return("XCPU"); 276 case SIGXFSZ: return("XFSZ"); 277 case SIGVTALRM: return("VTALRM"); 278 case SIGPROF: return("PROF"); 279 case SIGWINCH: return("WINCH"); 280 #ifdef SIGLOST 281 case SIGLOST: return("LOST"); 282 #endif 283 case SIGUSR1: return("USR1"); 284 case SIGUSR2: return("USR2"); 285 } 286 snprintf(buf, sizeof(buf), "sig %d", s); 287 return(buf); 288 } 289 290 void 291 hup_handler(int s) 292 { 293 char logoutfile[MAXPATHLEN]; 294 295 close(0); 296 seteuid(0); 297 snprintf(logoutfile, sizeof(logoutfile), "%s.%s", _PATH_SLOGOUT, loginname); 298 if (access(logoutfile, R_OK|X_OK) != 0) { 299 strncpy(logoutfile, _PATH_SLOGOUT, sizeof(logoutfile)-1); 300 logoutfile[sizeof(logoutfile)-1] = '\0'; 301 } 302 if (access(logoutfile, R_OK|X_OK) == 0) { 303 char logincmd[2*MAXPATHLEN+32]; 304 305 snprintf(logincmd, sizeof(logincmd), "%s %d %ld %s", logoutfile, unit, speed, loginargs); 306 system(logincmd); 307 } 308 syslog(LOG_INFO, "closed %s slip unit %d (%s)\n", loginname, unit, 309 sigstr(s)); 310 if (unlink(pidfilename) < 0 && errno != ENOENT) 311 syslog(LOG_WARNING, "unable to delete pid file: %m"); 312 if (unlink(iffilename) < 0 && errno != ENOENT) 313 syslog(LOG_WARNING, "unable to delete if file: %m"); 314 exit(1); 315 /* NOTREACHED */ 316 } 317 318 319 /* Modify the slip line mode and add any compression or no-icmp flags. */ 320 void 321 line_flags(int unit) 322 { 323 struct ifreq ifr; 324 int s; 325 326 /* open a socket as the handle to the interface */ 327 s = socket(AF_INET, SOCK_DGRAM, 0); 328 if (s < 0) { 329 syslog(LOG_ERR, "socket: %m"); 330 exit(1); 331 } 332 sprintf(ifr.ifr_name, "sl%d", unit); 333 334 /* get the flags for the interface */ 335 if (ioctl(s, SIOCGIFFLAGS, (caddr_t)&ifr) < 0) { 336 syslog(LOG_ERR, "ioctl (SIOCGIFFLAGS): %m"); 337 exit(1); 338 } 339 340 /* Assert any compression or no-icmp flags. */ 341 #define SLMASK (~(IFF_LINK0 | IFF_LINK1 | IFF_LINK2)) 342 ifr.ifr_flags &= SLMASK; 343 ifr.ifr_flags |= slip_mode; 344 if (ioctl(s, SIOCSIFFLAGS, (caddr_t)&ifr) < 0) { 345 syslog(LOG_ERR, "ioctl (SIOCSIFFLAGS): %m"); 346 exit(1); 347 } 348 close(s); 349 } 350 351 int 352 main(int argc, char *argv[]) 353 { 354 int fd, s, ldisc; 355 char *name; 356 struct termios tios, otios; 357 char logincmd[2*BUFSIZ+32]; 358 extern uid_t getuid(); 359 360 FILE *pidfile; /* pid file */ 361 FILE *iffile; /* interfaces file */ 362 char *p; 363 int n; 364 char devnam[MAXPATHLEN] = _PATH_TTY; /* Device name */ 365 366 if ((name = strrchr(argv[0], '/')) == NULL) 367 name = argv[0]; 368 s = getdtablesize(); 369 for (fd = 3 ; fd < s ; fd++) 370 close(fd); 371 openlog(name, LOG_PID|LOG_PERROR, LOG_DAEMON); 372 uid = getuid(); 373 if (argc > 1) { 374 findid(argv[1]); 375 376 /* 377 * Disassociate from current controlling terminal, if any, 378 * and ensure that the slip line is our controlling terminal. 379 */ 380 if (daemon(1, 1)) { 381 syslog(LOG_ERR, "daemon(1, 1): %m"); 382 exit(1); 383 } 384 if (argc > 2) { 385 if ((fd = open(argv[2], O_RDWR)) == -1) { 386 syslog(LOG_ERR, "open %s: %m", argv[2]); 387 exit(2); 388 } 389 dup2(fd, 0); 390 if (fd > 2) 391 close(fd); 392 } 393 if (ioctl(0, TIOCSCTTY, 0) == -1) { 394 syslog(LOG_ERR, "ioctl (TIOCSCTTY): %m"); 395 exit(1); 396 } 397 if (tcsetpgrp(0, getpid()) < 0) { 398 syslog(LOG_ERR, "tcsetpgrp failed: %m"); 399 exit(1); 400 } 401 } else { 402 if ((name = getlogin()) == NULL) { 403 syslog(LOG_ERR, "access denied - login name not found\n"); 404 exit(1); 405 } 406 findid(name); 407 } 408 fchmod(0, 0600); 409 fprintf(stderr, "starting slip login for %s\n", loginname); 410 fprintf(stderr, "your address is %s\n\n", make_ipaddr()); 411 412 fflush(stderr); 413 sleep(1); 414 415 /* set up the line parameters */ 416 if (tcgetattr(0, &tios) < 0) { 417 syslog(LOG_ERR, "tcgetattr: %m"); 418 exit(1); 419 } 420 otios = tios; 421 cfmakeraw(&tios); 422 if (tcsetattr(0, TCSAFLUSH, &tios) < 0) { 423 syslog(LOG_ERR, "tcsetattr: %m"); 424 exit(1); 425 } 426 speed = cfgetispeed(&tios); 427 428 ldisc = SLIPDISC; 429 if (ioctl(0, TIOCSETD, &ldisc) < 0) { 430 syslog(LOG_ERR, "ioctl(TIOCSETD): %m"); 431 exit(1); 432 } 433 if (slunit >= 0 && ioctl(0, SLIOCSUNIT, &slunit) < 0) { 434 syslog(LOG_ERR, "ioctl (SLIOCSUNIT): %m"); 435 exit(1); 436 } 437 /* find out what unit number we were assigned */ 438 if (ioctl(0, SLIOCGUNIT, &unit) < 0) { 439 syslog(LOG_ERR, "ioctl (SLIOCGUNIT): %m"); 440 exit(1); 441 } 442 signal(SIGHUP, hup_handler); 443 signal(SIGTERM, hup_handler); 444 445 if (keepal > 0) { 446 signal(SIGURG, hup_handler); 447 if (ioctl(0, SLIOCSKEEPAL, &keepal) < 0) { 448 syslog(LOG_ERR, "ioctl(SLIOCSKEEPAL): %m"); 449 exit(1); 450 } 451 } 452 if (outfill > 0 && ioctl(0, SLIOCSOUTFILL, &outfill) < 0) { 453 syslog(LOG_ERR, "ioctl(SLIOCSOUTFILL): %m"); 454 exit(1); 455 } 456 457 /* write pid to file */ 458 pid = getpid(); 459 sprintf(ifname, "sl%d", unit); 460 sprintf(pidfilename, "%s%s.pid", _PATH_VARRUN, ifname); 461 if ((pidfile = fopen(pidfilename, "w")) != NULL) { 462 fprintf(pidfile, "%d\n", pid); 463 fclose(pidfile); 464 } else { 465 syslog(LOG_ERR, "Failed to create pid file %s: %m", 466 pidfilename); 467 pidfilename[0] = 0; 468 } 469 470 /* write interface unit number to file */ 471 p = ttyname(0); 472 if (p) 473 strcpy(devnam, p); 474 for (n = strlen(devnam); n > 0; n--) 475 if (devnam[n] == '/') { 476 n++; 477 break; 478 } 479 sprintf(iffilename, "%s%s.if", _PATH_VARRUN, &devnam[n]); 480 if ((iffile = fopen(iffilename, "w")) != NULL) { 481 fprintf(iffile, "sl%d\n", unit); 482 fclose(iffile); 483 } else { 484 syslog(LOG_ERR, "Failed to create if file %s: %m", iffilename); 485 iffilename[0] = 0; 486 } 487 488 489 syslog(LOG_INFO, "attaching slip unit %d for %s\n", unit, loginname); 490 snprintf(logincmd, sizeof(logincmd), "%s %d %ld %s", loginfile, unit, speed, 491 loginargs); 492 /* 493 * aim stdout and errout at /dev/null so logincmd output won't 494 * babble into the slip tty line. 495 */ 496 close(1); 497 if ((fd = open(_PATH_DEVNULL, O_WRONLY)) != 1) { 498 if (fd < 0) { 499 syslog(LOG_ERR, "open %s: %m", _PATH_DEVNULL); 500 exit(1); 501 } 502 dup2(fd, 1); 503 close(fd); 504 } 505 dup2(1, 2); 506 507 /* 508 * Run login and logout scripts as root (real and effective); 509 * current route(8) is setuid root, and checks the real uid 510 * to see whether changes are allowed (or just "route get"). 511 */ 512 setuid(0); 513 if (s = system(logincmd)) { 514 syslog(LOG_ERR, "%s login failed: exit status %d from %s", 515 loginname, s, loginfile); 516 exit(6); 517 } 518 519 /* Handle any compression or no-icmp flags. */ 520 line_flags(unit); 521 522 /* reset uid to users' to allow the user to give a signal. */ 523 seteuid(uid); 524 /* twiddle thumbs until we get a signal */ 525 while (1) 526 sigpause(0); 527 528 /* NOTREACHED */ 529 } 530