sliplogin.c revision 1.3
1 /*- 2 * Copyright (c) 1990 The Regents of the University of California. 3 * 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 char copyright[] = 36 "@(#) Copyright (c) 1990 The Regents of the University of California.\n\ 37 All rights reserved.\n"; 38 #endif /* not lint */ 39 40 #ifndef lint 41 /*static char sccsid[] = "from: @(#)sliplogin.c 5.6 (Berkeley) 3/2/91";*/ 42 static char rcsid[] = "$Id: sliplogin.c,v 1.3 1993/08/01 17:55:46 mycroft 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/signal.h> 74 #include <sys/file.h> 75 #include <sys/syslog.h> 76 #include <netdb.h> 77 78 #if BSD >= 199006 79 #define POSIX 80 #endif 81 #ifdef POSIX 82 #include <sys/termios.h> 83 #include <sys/ioctl.h> 84 #include <ttyent.h> 85 #else 86 #include <sgtty.h> 87 #endif 88 #include <netinet/in.h> 89 #include <net/if.h> 90 #include <net/if_slvar.h> 91 92 #include <stdio.h> 93 #include <errno.h> 94 #include <ctype.h> 95 #include <string.h> 96 #include "pathnames.h" 97 98 int unit; 99 int slip_mode; 100 int speed; 101 int uid; 102 char loginargs[BUFSIZ]; 103 char loginfile[MAXPATHLEN]; 104 char loginname[BUFSIZ]; 105 106 struct slip_modes { 107 char *sm_name; 108 int sm_value; 109 } modes[] = { 110 "normal", 0, 111 "compress", SC_COMPRESS, 112 "noicmp", SC_NOICMP, 113 "autocomp", SC_AUTOCOMP 114 }; 115 116 void 117 findid(name) 118 char *name; 119 { 120 FILE *fp; 121 static char slopt[5][16]; 122 static char laddr[16]; 123 static char raddr[16]; 124 static char mask[16]; 125 char user[16]; 126 int i, j, n; 127 128 (void)strcpy(loginname, name); 129 if ((fp = fopen(_PATH_ACCESS, "r")) == NULL) { 130 (void)fprintf(stderr, "sliplogin: %s: %s\n", 131 _PATH_ACCESS, strerror(errno)); 132 syslog(LOG_ERR, "%s: %m\n", _PATH_ACCESS); 133 exit(1); 134 } 135 while (fgets(loginargs, sizeof(loginargs) - 1, fp)) { 136 if (ferror(fp)) 137 break; 138 n = sscanf(loginargs, "%15s%*[ \t]%15s%*[ \t]%15s%*[ \t]%15s%*[ \t]%15s%*[ \t]%15s%*[ \t]%15s%*[ \t]%15s%*[ \t]%15s\n", 139 user, laddr, raddr, mask, slopt[0], slopt[1], 140 slopt[2], slopt[3], slopt[4]); 141 if (user[0] == '#' || isspace(user[0])) 142 continue; 143 if (strcmp(user, name) != 0) 144 continue; 145 146 slip_mode = 0; 147 for (i = 0; i < n - 4; i++) { 148 for (j = 0; j < sizeof(modes)/sizeof(struct slip_modes); 149 j++) { 150 if (strcmp(modes[j].sm_name, slopt[i]) == 0) { 151 slip_mode |= modes[j].sm_value; 152 break; 153 } 154 } 155 } 156 157 /* 158 * we've found the guy we're looking for -- see if 159 * there's a login file we can use. First check for 160 * one specific to this host. If none found, try for 161 * a generic one. 162 */ 163 (void)sprintf(loginfile, "%s.%s", _PATH_LOGIN, name); 164 if (access(loginfile, R_OK|X_OK) != 0) { 165 (void)strcpy(loginfile, _PATH_LOGIN); 166 if (access(loginfile, R_OK|X_OK)) { 167 fputs("access denied - no login file\n", 168 stderr); 169 syslog(LOG_ERR, 170 "access denied for %s - no %s\n", 171 name, _PATH_LOGIN); 172 exit(5); 173 } 174 } 175 176 (void) fclose(fp); 177 return; 178 } 179 (void)fprintf(stderr, "SLIP access denied for %s\n", name); 180 syslog(LOG_ERR, "SLIP access denied for %s\n", name); 181 exit(4); 182 /* NOTREACHED */ 183 } 184 185 char * 186 sigstr(s) 187 int s; 188 { 189 static char buf[32]; 190 191 switch (s) { 192 case SIGHUP: return("HUP"); 193 case SIGINT: return("INT"); 194 case SIGQUIT: return("QUIT"); 195 case SIGILL: return("ILL"); 196 case SIGTRAP: return("TRAP"); 197 case SIGIOT: return("IOT"); 198 case SIGEMT: return("EMT"); 199 case SIGFPE: return("FPE"); 200 case SIGKILL: return("KILL"); 201 case SIGBUS: return("BUS"); 202 case SIGSEGV: return("SEGV"); 203 case SIGSYS: return("SYS"); 204 case SIGPIPE: return("PIPE"); 205 case SIGALRM: return("ALRM"); 206 case SIGTERM: return("TERM"); 207 case SIGURG: return("URG"); 208 case SIGSTOP: return("STOP"); 209 case SIGTSTP: return("TSTP"); 210 case SIGCONT: return("CONT"); 211 case SIGCHLD: return("CHLD"); 212 case SIGTTIN: return("TTIN"); 213 case SIGTTOU: return("TTOU"); 214 case SIGIO: return("IO"); 215 case SIGXCPU: return("XCPU"); 216 case SIGXFSZ: return("XFSZ"); 217 case SIGVTALRM: return("VTALRM"); 218 case SIGPROF: return("PROF"); 219 case SIGWINCH: return("WINCH"); 220 #ifdef SIGLOST 221 case SIGLOST: return("LOST"); 222 #endif 223 case SIGUSR1: return("USR1"); 224 case SIGUSR2: return("USR2"); 225 } 226 (void)sprintf(buf, "sig %d", s); 227 return(buf); 228 } 229 230 void 231 hup_handler(s) 232 int s; 233 { 234 char logoutfile[MAXPATHLEN]; 235 236 (void)sprintf(logoutfile, "%s.%s", _PATH_LOGOUT, loginname); 237 if (access(logoutfile, R_OK|X_OK) != 0) 238 (void)strcpy(logoutfile, _PATH_LOGOUT); 239 if (access(logoutfile, R_OK|X_OK) == 0) { 240 char logincmd[2*MAXPATHLEN+32]; 241 242 (void) sprintf(logincmd, "%s %d %d %s", logoutfile, unit, speed, 243 loginargs); 244 (void) system(logincmd); 245 } 246 (void) close(0); 247 syslog(LOG_INFO, "closed %s slip unit %d (%s)\n", loginname, unit, 248 sigstr(s)); 249 exit(1); 250 /* NOTREACHED */ 251 } 252 253 main(argc, argv) 254 int argc; 255 char *argv[]; 256 { 257 int fd, s, ldisc, odisc; 258 char *name; 259 #ifdef POSIX 260 struct termios tios, otios; 261 #else 262 struct sgttyb tty, otty; 263 #endif 264 char logincmd[2*BUFSIZ+32]; 265 extern uid_t getuid(); 266 267 if ((name = strrchr(argv[0], '/')) == NULL) 268 name = argv[0]; 269 s = getdtablesize(); 270 for (fd = 3 ; fd < s ; fd++) 271 (void) close(fd); 272 openlog(name, LOG_PID, LOG_DAEMON); 273 uid = getuid(); 274 if (argc > 1) { 275 findid(argv[1]); 276 277 /* 278 * Disassociate from current controlling terminal, if any, 279 * and ensure that the slip line is our controlling terminal. 280 */ 281 #ifdef POSIX 282 if (fork() > 0) 283 exit(0); 284 if (setsid() < 0) 285 perror("setsid"); 286 #else 287 if ((fd = open("/dev/tty", O_RDONLY, 0)) >= 0) { 288 extern char *ttyname(); 289 290 (void) ioctl(fd, TIOCNOTTY, (caddr_t)0); 291 (void) close(fd); 292 /* open slip tty again to acquire as controlling tty? */ 293 fd = open(ttyname(0), O_RDWR, 0); 294 if (fd >= 0) 295 (void) close(fd); 296 } 297 (void) setpgrp(0, getpid()); 298 #endif 299 if (argc > 2) { 300 if ((fd = open(argv[2], O_RDWR)) == -1) { 301 perror(argv[2]); 302 exit(2); 303 } 304 (void) dup2(fd, 0); 305 if (fd > 2) 306 close(fd); 307 } 308 #ifdef TIOCSCTTY 309 if (ioctl(0, TIOCSCTTY, (caddr_t)0) != 0) 310 perror("ioctl (TIOCSCTTY)"); 311 #endif 312 } else { 313 extern char *getlogin(); 314 315 if ((name = getlogin()) == NULL) { 316 (void) fprintf(stderr, "access denied - no username\n"); 317 syslog(LOG_ERR, "access denied - getlogin returned 0\n"); 318 exit(1); 319 } 320 findid(name); 321 } 322 (void) fchmod(0, 0600); 323 (void) fprintf(stderr, "starting slip login for %s\n", loginname); 324 #ifdef POSIX 325 /* set up the line parameters */ 326 if (tcgetattr(0, &tios) < 0) { 327 syslog(LOG_ERR, "tcgetattr: %m"); 328 exit(1); 329 } 330 otios = tios; 331 cfmakeraw(&tios); 332 tios.c_iflag &= ~IMAXBEL; 333 if (tcsetattr(0, TCSAFLUSH, &tios) < 0) { 334 syslog(LOG_ERR, "tcsetattr: %m"); 335 exit(1); 336 } 337 speed = cfgetispeed(&tios); 338 #else 339 /* set up the line parameters */ 340 if (ioctl(0, TIOCGETP, (caddr_t)&tty) < 0) { 341 syslog(LOG_ERR, "ioctl (TIOCGETP): %m"); 342 exit(1); 343 } 344 otty = tty; 345 speed = tty.sg_ispeed; 346 tty.sg_flags = RAW | ANYP; 347 if (ioctl(0, TIOCSETP, (caddr_t)&tty) < 0) { 348 syslog(LOG_ERR, "ioctl (TIOCSETP): %m"); 349 exit(1); 350 } 351 #endif 352 /* find out what ldisc we started with */ 353 if (ioctl(0, TIOCGETD, (caddr_t)&odisc) < 0) { 354 syslog(LOG_ERR, "ioctl(TIOCGETD) (1): %m"); 355 exit(1); 356 } 357 ldisc = SLIPDISC; 358 if (ioctl(0, TIOCSETD, (caddr_t)&ldisc) < 0) { 359 syslog(LOG_ERR, "ioctl(TIOCSETD): %m"); 360 exit(1); 361 } 362 /* find out what unit number we were assigned */ 363 if (ioctl(0, SLIOCGUNIT, (caddr_t)&unit) < 0) { 364 syslog(LOG_ERR, "ioctl (SLIOCGUNIT): %m"); 365 exit(1); 366 } 367 (void) signal(SIGHUP, hup_handler); 368 (void) signal(SIGTERM, hup_handler); 369 370 syslog(LOG_INFO, "attaching slip unit %d for %s\n", unit, loginname); 371 (void)sprintf(logincmd, "%s %d %d %s", loginfile, unit, speed, 372 loginargs); 373 /* 374 * aim stdout and errout at /dev/null so logincmd output won't 375 * babble into the slip tty line. 376 */ 377 (void) close(1); 378 if ((fd = open(_PATH_DEVNULL, O_WRONLY)) != 1) { 379 if (fd < 0) { 380 syslog(LOG_ERR, "open /dev/null: %m"); 381 exit(1); 382 } 383 (void) dup2(fd, 1); 384 (void) close(fd); 385 } 386 (void) dup2(1, 2); 387 388 /* 389 * Run login and logout scripts as root (real and effective); 390 * current route(8) is setuid root, and checks the real uid 391 * to see whether changes are allowed (or just "route get"). 392 */ 393 (void) setuid(0); 394 if (s = system(logincmd)) { 395 syslog(LOG_ERR, "%s login failed: exit status %d from %s", 396 loginname, s, loginfile); 397 (void) ioctl(0, TIOCSETD, (caddr_t)&odisc); 398 exit(6); 399 } 400 if (ioctl(0, SLIOCSFLAGS, (caddr_t)&slip_mode) < 0) { 401 syslog(LOG_ERR, "ioctl (SLIOCSFLAGS): %m"); 402 exit(1); 403 } 404 405 /* twiddle thumbs until we get a signal */ 406 while (1) 407 sigpause(0); 408 409 /* NOTREACHED */ 410 } 411
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