usr.sbin/sliplogin/sliplogin.c

   1 /*      $NetBSD: sliplogin.c,v 1.21 2004/10/30 15:44:04 dsl Exp $       */
   2
   3 /*-
   4  * Copyright (c) 1990, 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  * 3. Neither the name of the University nor the names of its contributors
  16  *    may be used to endorse or promote products derived from this software
  17  *    without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  29  * SUCH DAMAGE.
  30  */
  31
  32 #include <sys/cdefs.h>
  33 #ifndef lint
  34 __COPYRIGHT("@(#) Copyright (c) 1990, 1993\
  35  The Regents of the University of California.  All rights reserved.");
  36 #endif /* not lint */
  37
  38 #ifndef lint
  39 #if 0
  40 static char sccsid[] = "@(#)sliplogin.c 8.2 (Berkeley) 2/1/94";
  41 #else
  42 __RCSID("$NetBSD: sliplogin.c,v 1.21 2004/10/30 15:44:04 dsl Exp $");
  43 #endif
  44 #endif /* not lint */
  45
  46 /*
  47  * sliplogin.c
  48  * [MUST BE RUN SUID, SLOPEN DOES A SUSER()!]
  49  *
  50  * This program initializes its own tty port to be an async TCP/IP interface.
  51  * It sets the line discipline to slip, invokes a shell script to initialize
  52  * the network interface, then pauses forever waiting for hangup.
  53  *
  54  * It is a remote descendant of several similar programs with incestuous ties:
  55  * - Kirk Smith's slipconf, modified by Richard Johnsson @ DEC WRL.
  56  * - slattach, probably by Rick Adams but touched by countless hordes.
  57  * - the original sliplogin for 4.2bsd, Doug Kingston the mover behind it.
  58  *
  59  * There are two forms of usage:
  60  *
  61  * "sliplogin"
  62  * Invoked simply as "sliplogin", the program looks up the username
  63  * in the file /etc/slip.hosts.
  64  * If an entry is found, the line on fd0 is configured for SLIP operation
  65  * as specified in the file.
  66  *
  67  * "sliplogin IPhostlogin </dev/ttyb"
  68  * Invoked by root with a username, the name is looked up in the
  69  * /etc/slip.hosts file and if found fd0 is configured as in case 1.
  70  */
  71
  72 #include <sys/types.h>
  73 #include <sys/file.h>
  74 #include <sys/param.h>
  75 #include <sys/socket.h>
  76 #include <sys/stat.h>
  77 #include <sys/syslog.h>
  78
  79 #if BSD >= 199006
  80 #define POSIX
  81 #endif
  82 #ifdef POSIX
  83 #include <termios.h>
  84 #include <sys/ioctl.h>
  85 #include <ttyent.h>
  86 #else
  87 #include <sgtty.h>
  88 #endif
  89 #include <net/slip.h>
  90
  91 #include <ctype.h>
  92 #include <err.h>
  93 #include <errno.h>
  94 #include <netdb.h>
  95 #include <signal.h>
  96 #include <stdio.h>
  97 #include <stdlib.h>
  98 #include <string.h>
  99 #include <unistd.h>
 100
 101 #include "pathnames.h"
 102
 103 int     unit;
 104 int     speed;
 105 int     uid;
 106 char    loginargs[BUFSIZ];
 107 char    loginfile[MAXPATHLEN];
 108 char    loginname[BUFSIZ];
 109
 110 void     findid __P((char *));
 111 void    hup_handler __P((int));
 112 int     main __P((int, char **));
 113 const char *sigstr __P((int));
 114
 115 void
 116 findid(name)
 117         char *name;
 118 {
 119         FILE *fp;
 120         static char slopt[5][16];
 121         static char laddr[16];
 122         static char raddr[16];
 123         static char mask[16];
 124         char user[16];
 125         int n;
 126
 127         (void)strlcpy(loginname, name, sizeof(loginname));
 128         if ((fp = fopen(_PATH_ACCESS, "r")) == NULL) {
 129                 syslog(LOG_ERR, "%s: %m\n", _PATH_ACCESS);
 130                 err(1, "%s", _PATH_ACCESS);
 131         }
 132         while (fgets(loginargs, sizeof(loginargs) - 1, fp)) {
 133                 if (ferror(fp))
 134                         break;
 135                 n = sscanf(loginargs, "%15s%*[ \t]%15s%*[ \t]%15s%*[ \t]%15s%*[ \t]%15s%*[ \t]%15s%*[ \t]%15s%*[ \t]%15s%*[ \t]%15s\n",
 136                         user, laddr, raddr, mask, slopt[0], slopt[1],
 137                         slopt[2], slopt[3], slopt[4]);
 138                 if (user[0] == '#' || isspace((unsigned char)user[0]))
 139                         continue;
 140                 if (strcmp(user, name) != 0)
 141                         continue;
 142
 143                 /*
 144                  * we've found the guy we're looking for -- see if
 145                  * there's a login file we can use.  First check for
 146                  * one specific to this host.  If none found, try for
 147                  * a generic one.
 148                  */
 149                 (void)snprintf(loginfile, sizeof loginfile, "%s.%s",
 150                     _PATH_LOGIN, name);
 151                 if (access(loginfile, R_OK|X_OK) != 0) {
 152                         (void)strlcpy(loginfile, _PATH_LOGIN, sizeof(loginfile));
 153                         if (access(loginfile, R_OK|X_OK)) {
 154                                 fputs("access denied - no login file\n",
 155                                       stderr);
 156                                 syslog(LOG_ERR,
 157                                        "access denied for %s - no %s\n",
 158                                        name, _PATH_LOGIN);
 159                                 exit(5);
 160                         }
 161                 }
 162
 163                 (void)fclose(fp);
 164                 return;
 165         }
 166         syslog(LOG_ERR, "SLIP access denied for %s\n", name);
 167         errx(1, "SLIP access denied for %s", name);
 168         /* NOTREACHED */
 169 }
 170
 171 const char *
 172 sigstr(s)
 173         int s;
 174 {
 175
 176         if (s > 0 && s < NSIG)
 177                 return (sys_signame[s]);
 178         else {
 179                 static char buf[32];
 180
 181                 (void)snprintf(buf, sizeof buf, "sig %d", s);
 182                 return (buf);
 183         }
 184 }
 185
 186 void
 187 hup_handler(s)
 188         int s;
 189 {
 190         char logoutfile[MAXPATHLEN];
 191
 192         (void)snprintf(logoutfile, sizeof logoutfile, "%s.%s", _PATH_LOGOUT,
 193             loginname);
 194         if (access(logoutfile, R_OK|X_OK) != 0)
 195                 (void)strlcpy(logoutfile, _PATH_LOGOUT, sizeof(logoutfile));
 196         if (access(logoutfile, R_OK|X_OK) == 0) {
 197                 char logincmd[2*MAXPATHLEN+32];
 198
 199                 (void)snprintf(logincmd, sizeof logincmd, "%s %d %d %s",
 200                     logoutfile, unit, speed, loginargs);
 201                 (void)system(logincmd);
 202         }
 203         (void)close(0);
 204         syslog(LOG_INFO, "closed %s slip unit %d (%s)\n", loginname, unit,
 205                sigstr(s));
 206         exit(1);
 207         /* NOTREACHED */
 208 }
 209
 210 int
 211 main(argc, argv)
 212         int argc;
 213         char *argv[];
 214 {
 215         int fd, s, ldisc, odisc;
 216         char *name;
 217 #ifdef POSIX
 218         struct termios tios, otios;
 219 #else
 220         struct sgttyb tty, otty;
 221 #endif
 222         char logincmd[2*BUFSIZ+32];
 223
 224         if (strlen(argv[0]) > MAXLOGNAME)
 225                 errx(1, "login %s too long", argv[0]);
 226         if ((name = strrchr(argv[0], '/')) == NULL)
 227                 name = argv[0];
 228         else
 229                 name++;
 230         s = getdtablesize();
 231         for (fd = 3 ; fd < s ; fd++)
 232                 (void)close(fd);
 233         openlog(name, LOG_PID, LOG_DAEMON);
 234         uid = getuid();
 235         if (argc > 1) {
 236                 findid(argv[1]);
 237
 238                 /*
 239                  * Disassociate from current controlling terminal, if any,
 240                  * and ensure that the slip line is our controlling terminal.
 241                  */
 242 #ifdef POSIX
 243                 switch (fork()) {
 244                 case -1:
 245                         perror("fork");
 246                         syslog(LOG_ERR, "could not fork: %m");
 247                         exit(1);
 248                 case 0:
 249                         break;
 250                 default:
 251                         exit(0);
 252                 }
 253                 if (setsid() < 0)
 254                         perror("setsid");
 255 #else
 256                 if ((fd = open("/dev/tty", O_RDONLY, 0)) >= 0) {
 257                         extern char *ttyname();
 258
 259                         (void)ioctl(fd, TIOCNOTTY, (caddr_t)0);
 260                         (void)close(fd);
 261                         /* open slip tty again to acquire as controlling tty? */
 262                         fd = open(ttyname(0), O_RDWR, 0);
 263                         if (fd >= 0)
 264                                 (void)close(fd);
 265                 }
 266                 (void)setpgrp(0, getpid());
 267 #endif
 268                 if (argc > 2) {
 269                         if ((fd = open(argv[2], O_RDWR)) == -1) {
 270                                 perror(argv[2]);
 271                                 exit(2);
 272                         }
 273                         (void)dup2(fd, 0);
 274                         if (fd > 2)
 275                                 close(fd);
 276                 }
 277 #ifdef TIOCSCTTY
 278                 if (ioctl(STDIN_FILENO, TIOCSCTTY, (caddr_t)0) != 0)
 279                         perror("ioctl (TIOCSCTTY)");
 280 #endif
 281         } else {
 282                 if ((name = getlogin()) == NULL) {
 283                         syslog(LOG_ERR,
 284                             "access denied - getlogin returned 0\n");
 285                         errx(1, "access denied - no username");
 286                 }
 287                 findid(name);
 288         }
 289         if (!isatty(STDIN_FILENO)) {
 290                 syslog(LOG_ERR, "stdin not a tty");
 291                 errx(1, "stdin not a tty");
 292         }
 293         (void)fchmod(STDIN_FILENO, 0600);
 294         warnx("starting slip login for %s", loginname);
 295 #ifdef POSIX
 296         /* set up the line parameters */
 297         if (tcgetattr(STDIN_FILENO, &tios) < 0) {
 298                 syslog(LOG_ERR, "tcgetattr: %m");
 299                 exit(1);
 300         }
 301         otios = tios;
 302         cfmakeraw(&tios);
 303         tios.c_iflag &= ~IMAXBEL;
 304         if (tcsetattr(STDIN_FILENO, TCSAFLUSH, &tios) < 0) {
 305                 syslog(LOG_ERR, "tcsetattr: %m");
 306                 exit(1);
 307         }
 308         speed = cfgetispeed(&tios);
 309 #else
 310         /* set up the line parameters */
 311         if (ioctl(STDIN_FILENO, TIOCGETP, (caddr_t)&tty) < 0) {
 312                 syslog(LOG_ERR, "ioctl (TIOCGETP): %m");
 313                 exit(1);
 314         }
 315         otty = tty;
 316         speed = tty.sg_ispeed;
 317         tty.sg_flags = RAW | ANYP;
 318         if (ioctl(STDIN_FILENO, TIOCSETP, (caddr_t)&tty) < 0) {
 319                 syslog(LOG_ERR, "ioctl (TIOCSETP): %m");
 320                 exit(1);
 321         }
 322 #endif
 323         /* find out what ldisc we started with */
 324         if (ioctl(STDIN_FILENO, TIOCGETD, (caddr_t)&odisc) < 0) {
 325                 syslog(LOG_ERR, "ioctl(TIOCGETD) (1): %m");
 326                 exit(1);
 327         }
 328         ldisc = SLIPDISC;
 329         if (ioctl(STDIN_FILENO, TIOCSETD, (caddr_t)&ldisc) < 0) {
 330                 syslog(LOG_ERR, "ioctl(TIOCSETD): %m");
 331                 exit(1);
 332         }
 333         /* find out what unit number we were assigned */
 334         if (ioctl(STDIN_FILENO, SLIOCGUNIT, (caddr_t)&unit) < 0) {
 335                 syslog(LOG_ERR, "ioctl (SLIOCGUNIT): %m");
 336                 exit(1);
 337         }
 338         (void)signal(SIGHUP, hup_handler);
 339         (void)signal(SIGTERM, hup_handler);
 340
 341         syslog(LOG_INFO, "attaching slip unit %d for %s\n", unit, loginname);
 342         (void)snprintf(logincmd, sizeof logincmd, "%s %d %d %s", loginfile,
 343             unit, speed, loginargs);
 344         /*
 345          * aim stdout and errout at /dev/null so logincmd output won't
 346          * babble into the slip tty line.
 347          */
 348         (void)close(1);
 349         if ((fd = open(_PATH_DEVNULL, O_WRONLY)) != 1) {
 350                 if (fd < 0) {
 351                         syslog(LOG_ERR, "open /dev/null: %m");
 352                         exit(1);
 353                 }
 354                 (void)dup2(fd, 1);
 355                 (void)close(fd);
 356         }
 357         (void)dup2(1, 2);
 358
 359         /*
 360          * Run login and logout scripts as root (real and effective);
 361          * current route(8) is setuid root, and checks the real uid
 362          * to see whether changes are allowed (or just "route get").
 363          */
 364         (void)setuid(0);
 365         if ((s = system(logincmd)) != 0) {
 366                 syslog(LOG_ERR, "%s login failed: exit status %d from %s",
 367                        loginname, s, loginfile);
 368                 (void)ioctl(STDIN_FILENO, TIOCSETD, (caddr_t)&odisc);
 369 #ifdef POSIX
 370                 (void)tcsetattr(STDIN_FILENO, TCSAFLUSH, &otios);
 371 #else
 372                 (void)ioctl(STDIN_FILENO, TIOCSETP, (caddr_t)&otty);
 373 #endif
 374                 exit(6);
 375         }
 376
 377         /* twiddle thumbs until we get a signal */
 378         while (1)
 379                 sigpause(0);
 380
 381         /* NOTREACHED */
 382 }