libexec/rlogind/rlogind.c

   1 /*-
   2  * Copyright (c) 1983, 1988, 1989, 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) 1983, 1988, 1989, 1993 The Regents of the University of California.  All rights reserved.
  30  * @(#)rlogind.c        8.1 (Berkeley) 6/4/93
  31  * $FreeBSD: src/libexec/rlogind/rlogind.c,v 1.29.2.5 2000/12/07 15:02:31 ru Exp $
  32  */
  33
  34 /*
  35  * remote login server:
  36  *      \0
  37  *      remuser\0
  38  *      locuser\0
  39  *      terminal_type/speed\0
  40  *      data
  41  */
  42
  43 #define FD_SETSIZE      16              /* don't need many bits for select */
  44 #include <sys/types.h>
  45 #include <sys/param.h>
  46 #include <sys/stat.h>
  47 #include <sys/ioctl.h>
  48 #include <signal.h>
  49 #include <termios.h>
  50
  51 #include <sys/socket.h>
  52 #include <netinet/in.h>
  53 #include <netinet/in_systm.h>
  54 #include <netinet/ip.h>
  55 #include <netinet/tcp.h>
  56 #include <arpa/inet.h>
  57 #include <netdb.h>
  58
  59 #include <errno.h>
  60 #include <libutil.h>
  61 #include <pwd.h>
  62 #include <syslog.h>
  63 #include <stdio.h>
  64 #include <stdlib.h>
  65 #include <string.h>
  66 #include <unistd.h>
  67 #include "pathnames.h"
  68
  69
  70 #ifndef TIOCPKT_WINDOW
  71 #define TIOCPKT_WINDOW 0x80
  72 #endif
  73
  74 #define         ARGSTR                  "Dalnx"
  75
  76 /* wrapper for KAME-special getnameinfo() */
  77 #ifndef NI_WITHSCOPEID
  78 #define NI_WITHSCOPEID  0
  79 #endif
  80
  81 extern int __check_rhosts_file;
  82 extern  char **environ;
  83
  84 char    *env[2];
  85 #define NMAX 30
  86 char    lusername[NMAX+1], rusername[NMAX+1];
  87 static  char term[64] = "TERM=";
  88 #define ENVSIZE (sizeof("TERM=")-1)     /* skip null for concatenation */
  89 int     keepalive = 1;
  90 int     check_all = 0;
  91 int     no_delay;
  92
  93 struct  passwd *pwd;
  94
  95 union sockunion {
  96         struct sockinet {
  97                 u_char si_len;
  98                 u_char si_family;
  99                 u_short si_port;
 100         } su_si;
 101         struct sockaddr_in  su_sin;
 102         struct sockaddr_in6 su_sin6;
 103 };
 104 #define su_len          su_si.si_len
 105 #define su_family       su_si.si_family
 106 #define su_port         su_si.si_port
 107
 108 void    doit(int, union sockunion *);
 109 int     control(int, char *, int);
 110 void    protocol(int, int);
 111 void    cleanup(int);
 112 void    fatal(int, const char *, int);
 113 int     do_rlogin(union sockunion *);
 114 void    getstr(char *, int, const char *);
 115 void    setup_term(int);
 116 int     do_krb_login(struct sockaddr_in *);
 117 void    usage(void);
 118
 119
 120 int
 121 main(int argc, char *argv[])
 122 {
 123         union sockunion from;
 124         socklen_t fromlen;
 125         int ch, on;
 126
 127         openlog("rlogind", LOG_PID | LOG_CONS, LOG_AUTH);
 128
 129         opterr = 0;
 130         while ((ch = getopt(argc, argv, ARGSTR)) != -1)
 131                 switch (ch) {
 132                 case 'D':
 133                         no_delay = 1;
 134                         break;
 135                 case 'a':
 136                         check_all = 1;
 137                         break;
 138                 case 'l':
 139                         __check_rhosts_file = 0;
 140                         break;
 141                 case 'n':
 142                         keepalive = 0;
 143                         break;
 144 #ifdef CRYPT
 145                 case 'x':
 146                         doencrypt = 1;
 147                         break;
 148 #endif
 149                 case '?':
 150                 default:
 151                         usage();
 152                         break;
 153                 }
 154         argc -= optind;
 155         argv += optind;
 156
 157         fromlen = sizeof (from);
 158         if (getpeername(0, (struct sockaddr *)&from, &fromlen) < 0) {
 159                 syslog(LOG_ERR,"Can't get peer name of remote host: %m");
 160                 fatal(STDERR_FILENO, "Can't get peer name of remote host", 1);
 161         }
 162         on = 1;
 163         if (keepalive &&
 164             setsockopt(0, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof (on)) < 0)
 165                 syslog(LOG_WARNING, "setsockopt (SO_KEEPALIVE): %m");
 166         if (no_delay &&
 167             setsockopt(0, IPPROTO_TCP, TCP_NODELAY, &on, sizeof(on)) < 0)
 168                 syslog(LOG_WARNING, "setsockopt (TCP_NODELAY): %m");
 169         if (from.su_family == AF_INET)
 170       {
 171         on = IPTOS_LOWDELAY;
 172         if (setsockopt(0, IPPROTO_IP, IP_TOS, (char *)&on, sizeof(int)) < 0)
 173                 syslog(LOG_WARNING, "setsockopt (IP_TOS): %m");
 174       }
 175
 176         doit(0, &from);
 177         return 0;
 178 }
 179
 180 int     child;
 181 int     netf;
 182 char    line[MAXPATHLEN];
 183 int     confirmed;
 184
 185 struct winsize win = { 0, 0, 0, 0 };
 186
 187
 188 void
 189 doit(int f, union sockunion *fromp)
 190 {
 191         int master, pid, on = 1;
 192         int authenticated = 0;
 193         char hostname[2 * MAXHOSTNAMELEN + 1];
 194         char nameinfo[2 * INET6_ADDRSTRLEN + 1];
 195         u_char c;
 196
 197         alarm(60);
 198         read(f, &c, 1);
 199
 200         if (c != 0)
 201                 exit(1);
 202
 203         alarm(0);
 204
 205         realhostname_sa(hostname, sizeof(hostname) - 1,
 206                             (struct sockaddr *)fromp, fromp->su_len);
 207         /* error check ? */
 208         fromp->su_port = ntohs((u_short)fromp->su_port);
 209         hostname[sizeof(hostname) - 1] = '\0';
 210
 211         {
 212                 if ((fromp->su_family != AF_INET
 213 #ifdef INET6
 214                   && fromp->su_family != AF_INET6
 215 #endif
 216                      ) ||
 217                     fromp->su_port >= IPPORT_RESERVED ||
 218                     fromp->su_port < IPPORT_RESERVED/2) {
 219                         getnameinfo((struct sockaddr *)fromp,
 220                                     fromp->su_len,
 221                                     nameinfo, sizeof(nameinfo), NULL, 0,
 222                                     NI_NUMERICHOST|NI_WITHSCOPEID);
 223                         /* error check ? */
 224                         syslog(LOG_NOTICE, "Connection from %s on illegal port",
 225                                nameinfo);
 226                         fatal(f, "Permission denied", 0);
 227                 }
 228 #ifdef IP_OPTIONS
 229                 if (fromp->su_family == AF_INET)
 230               {
 231                 u_char optbuf[BUFSIZ/3];
 232                 socklen_t optsize = sizeof(optbuf), i;
 233                 int ipproto;
 234                 struct protoent *ip;
 235
 236                 if ((ip = getprotobyname("ip")) != NULL)
 237                         ipproto = ip->p_proto;
 238                 else
 239                         ipproto = IPPROTO_IP;
 240                 if (getsockopt(0, ipproto, IP_OPTIONS, (char *)optbuf,
 241                     &optsize) == 0 && optsize != 0) {
 242                         for (i = 0; i < optsize; ) {
 243                                 c = optbuf[i];
 244                                 if (c == IPOPT_LSRR || c == IPOPT_SSRR) {
 245                                         syslog(LOG_NOTICE,
 246                                                 "Connection refused from %s with IP option %s",
 247                                                 inet_ntoa(fromp->su_sin.sin_addr),
 248                                                 c == IPOPT_LSRR ? "LSRR" : "SSRR");
 249                                         exit(1);
 250                                 }
 251                                 if (c == IPOPT_EOL)
 252                                         break;
 253                                 i += (c == IPOPT_NOP) ? 1 : optbuf[i+1];
 254                         }
 255                 }
 256               }
 257 #endif
 258                 if (do_rlogin(fromp) == 0)
 259                         authenticated++;
 260         }
 261         if (confirmed == 0) {
 262                 write(f, "", 1);
 263                 confirmed = 1;          /* we sent the null! */
 264         }
 265 #ifdef  CRYPT
 266         if (doencrypt) {
 267                 des_enc_write(f, SECURE_MESSAGE, strlen(SECURE_MESSAGE),
 268                     schedule, &kdata->session);
 269         }
 270 #endif
 271         netf = f;
 272
 273         pid = forkpty(&master, line, NULL, &win);
 274         if (pid < 0) {
 275                 if (errno == ENOENT)
 276                         fatal(f, "Out of ptys", 0);
 277                 else
 278                         fatal(f, "Forkpty", 1);
 279         }
 280         if (pid == 0) {
 281                 if (f > 2)      /* f should always be 0, but... */
 282                         close(f);
 283                 setup_term(0);
 284                  if (*lusername=='-') {
 285                         syslog(LOG_ERR, "tried to pass user \"%s\" to login",
 286                                lusername);
 287                         fatal(STDERR_FILENO, "invalid user", 0);
 288                 }
 289                 if (authenticated) {
 290                         execl(_PATH_LOGIN, "login", "-p",
 291                             "-h", hostname, "-f", lusername, NULL);
 292                 } else
 293                         execl(_PATH_LOGIN, "login", "-p",
 294                             "-h", hostname, lusername, NULL);
 295                 fatal(STDERR_FILENO, _PATH_LOGIN, 1);
 296                 /*NOTREACHED*/
 297         }
 298 #ifdef  CRYPT
 299         /*
 300          * If encrypted, don't turn on NBIO or the des read/write
 301          * routines will croak.
 302          */
 303
 304         if (!doencrypt)
 305 #endif
 306                 ioctl(f, FIONBIO, &on);
 307         ioctl(master, FIONBIO, &on);
 308         ioctl(master, TIOCPKT, &on);
 309         signal(SIGCHLD, cleanup);
 310         protocol(f, master);
 311         signal(SIGCHLD, SIG_IGN);
 312         cleanup(0);
 313 }
 314
 315 char    magic[2] = { 0377, 0377 };
 316 char    oobdata[] = {TIOCPKT_WINDOW};
 317
 318 /*
 319  * Handle a "control" request (signaled by magic being present)
 320  * in the data stream.  For now, we are only willing to handle
 321  * window size changes.
 322  */
 323 int
 324 control(int pty, char *cp, int n)
 325 {
 326         struct winsize w;
 327
 328         if (n < 4 + (int)sizeof(w) || cp[2] != 's' || cp[3] != 's')
 329                 return (0);
 330         oobdata[0] &= ~TIOCPKT_WINDOW;  /* we know he heard */
 331         bcopy(cp+4, (char *)&w, sizeof(w));
 332         w.ws_row = ntohs(w.ws_row);
 333         w.ws_col = ntohs(w.ws_col);
 334         w.ws_xpixel = ntohs(w.ws_xpixel);
 335         w.ws_ypixel = ntohs(w.ws_ypixel);
 336         ioctl(pty, TIOCSWINSZ, &w);
 337         return (4+sizeof (w));
 338 }
 339
 340 /*
 341  * rlogin "protocol" machine.
 342  */
 343 void
 344 protocol(int f, int p)
 345 {
 346         char pibuf[1024+1], fibuf[1024], *pbp = NULL, *fbp = NULL;
 347         int pcc = 0, fcc = 0;
 348         int cc, nfd, n;
 349         char cntl;
 350
 351         /*
 352          * Must ignore SIGTTOU, otherwise we'll stop
 353          * when we try and set slave pty's window shape
 354          * (our controlling tty is the master pty).
 355          */
 356         signal(SIGTTOU, SIG_IGN);
 357         send(f, oobdata, 1, MSG_OOB);   /* indicate new rlogin */
 358         if (f > p)
 359                 nfd = f + 1;
 360         else
 361                 nfd = p + 1;
 362         if (nfd > FD_SETSIZE) {
 363                 syslog(LOG_ERR, "select mask too small, increase FD_SETSIZE");
 364                 fatal(f, "internal error (select mask too small)", 0);
 365         }
 366         for (;;) {
 367                 fd_set ibits, obits, ebits, *omask;
 368
 369                 FD_ZERO(&ebits);
 370                 FD_ZERO(&ibits);
 371                 FD_ZERO(&obits);
 372                 omask = NULL;
 373                 if (fcc) {
 374                         FD_SET(p, &obits);
 375                         omask = &obits;
 376                 } else
 377                         FD_SET(f, &ibits);
 378                 if (pcc >= 0) {
 379                         if (pcc) {
 380                                 FD_SET(f, &obits);
 381                                 omask = &obits;
 382                         } else
 383                                 FD_SET(p, &ibits);
 384                 }
 385                 FD_SET(p, &ebits);
 386                 if ((n = select(nfd, &ibits, omask, &ebits, 0)) < 0) {
 387                         if (errno == EINTR)
 388                                 continue;
 389                         fatal(f, "select", 1);
 390                 }
 391                 if (n == 0) {
 392                         /* shouldn't happen... */
 393                         sleep(5);
 394                         continue;
 395                 }
 396 #define pkcontrol(c)    ((c)&(TIOCPKT_FLUSHWRITE|TIOCPKT_NOSTOP|TIOCPKT_DOSTOP))
 397                 if (FD_ISSET(p, &ebits)) {
 398                         cc = read(p, &cntl, 1);
 399                         if (cc == 1 && pkcontrol(cntl)) {
 400                                 cntl |= oobdata[0];
 401                                 send(f, &cntl, 1, MSG_OOB);
 402                                 if (cntl & TIOCPKT_FLUSHWRITE) {
 403                                         pcc = 0;
 404                                         FD_CLR(p, &ibits);
 405                                 }
 406                         }
 407                 }
 408                 if (FD_ISSET(f, &ibits)) {
 409 #ifdef  CRYPT
 410                         if (doencrypt)
 411                                 fcc = des_enc_read(f, fibuf, sizeof(fibuf),
 412                                         schedule, &kdata->session);
 413                         else
 414 #endif
 415                                 fcc = read(f, fibuf, sizeof(fibuf));
 416                         if (fcc < 0 && errno == EWOULDBLOCK)
 417                                 fcc = 0;
 418                         else {
 419                                 register char *cp;
 420                                 int left;
 421
 422                                 if (fcc <= 0)
 423                                         break;
 424                                 fbp = fibuf;
 425
 426                         top:
 427                                 for (cp = fibuf; cp < fibuf+fcc-1; cp++)
 428                                         if (cp[0] == magic[0] &&
 429                                             cp[1] == magic[1]) {
 430                                                 left = fcc - (cp-fibuf);
 431                                                 n = control(p, cp, left);
 432                                                 if (n) {
 433                                                         left -= n;
 434                                                         if (left > 0)
 435                                                                 bcopy(cp+n, cp, left);
 436                                                         fcc -= n;
 437                                                         goto top; /* n^2 */
 438                                                 }
 439                                         }
 440                                 FD_SET(p, &obits);              /* try write */
 441                         }
 442                 }
 443
 444                 if (FD_ISSET(p, &obits) && fcc > 0) {
 445                         cc = write(p, fbp, fcc);
 446                         if (cc > 0) {
 447                                 fcc -= cc;
 448                                 fbp += cc;
 449                         }
 450                 }
 451
 452                 if (FD_ISSET(p, &ibits)) {
 453                         pcc = read(p, pibuf, sizeof (pibuf));
 454                         pbp = pibuf;
 455                         if (pcc < 0 && errno == EWOULDBLOCK)
 456                                 pcc = 0;
 457                         else if (pcc <= 0)
 458                                 break;
 459                         else if (pibuf[0] == 0) {
 460                                 pbp++, pcc--;
 461 #ifdef  CRYPT
 462                                 if (!doencrypt)
 463 #endif
 464                                         FD_SET(f, &obits);      /* try write */
 465                         } else {
 466                                 if (pkcontrol(pibuf[0])) {
 467                                         pibuf[0] |= oobdata[0];
 468                                         send(f, &pibuf[0], 1, MSG_OOB);
 469                                 }
 470                                 pcc = 0;
 471                         }
 472                 }
 473                 if ((FD_ISSET(f, &obits)) && pcc > 0) {
 474 #ifdef  CRYPT
 475                         if (doencrypt)
 476                                 cc = des_enc_write(f, pbp, pcc,
 477                                         schedule, &kdata->session);
 478                         else
 479 #endif
 480                                 cc = write(f, pbp, pcc);
 481                         if (cc < 0 && errno == EWOULDBLOCK) {
 482                                 /*
 483                                  * This happens when we try write after read
 484                                  * from p, but some old kernels balk at large
 485                                  * writes even when select returns true.
 486                                  */
 487                                 if (!FD_ISSET(p, &ibits))
 488                                         sleep(5);
 489                                 continue;
 490                         }
 491                         if (cc > 0) {
 492                                 pcc -= cc;
 493                                 pbp += cc;
 494                         }
 495                 }
 496         }
 497 }
 498
 499 void
 500 cleanup(int signo __unused)
 501 {
 502         char *p;
 503
 504         p = line + sizeof(_PATH_DEV) - 1;
 505         if (logout(p))
 506                 logwtmp(p, "", "");
 507         chflags(line, 0);
 508         chmod(line, 0666);
 509         chown(line, 0, 0);
 510         *p = 'p';
 511         chflags(line, 0);
 512         chmod(line, 0666);
 513         chown(line, 0, 0);
 514         shutdown(netf, SHUT_RDWR);
 515         exit(1);
 516 }
 517
 518 void
 519 fatal(int f, const char *msg, int syserr)
 520 {
 521         int len;
 522         char buf[BUFSIZ], *bp = buf;
 523
 524         /*
 525          * Prepend binary one to message if we haven't sent
 526          * the magic null as confirmation.
 527          */
 528         if (!confirmed)
 529                 *bp++ = '\01';          /* error indicator */
 530         if (syserr)
 531                 len = snprintf(bp, sizeof(buf), "rlogind: %s: %s.\r\n",
 532                     msg, strerror(errno));
 533         else
 534                 len = snprintf(bp, sizeof(buf), "rlogind: %s.\r\n", msg);
 535         write(f, buf, bp + len - buf);
 536         exit(1);
 537 }
 538
 539 int
 540 do_rlogin(union sockunion *dest)
 541 {
 542
 543         getstr(rusername, sizeof(rusername), "remuser too long");
 544         getstr(lusername, sizeof(lusername), "locuser too long");
 545         getstr(term+ENVSIZE, sizeof(term)-ENVSIZE, "Terminal type too long");
 546
 547         pwd = getpwnam(lusername);
 548         if (pwd == NULL)
 549                 return (-1);
 550         /* XXX why don't we syslog() failure? */
 551
 552         return (iruserok_sa(dest, dest->su_len, pwd->pw_uid == 0, rusername,
 553                             lusername));
 554 }
 555
 556 void
 557 getstr(char *buf, int cnt, const char *errmsg)
 558 {
 559         char c;
 560
 561         do {
 562                 if (read(0, &c, 1) != 1)
 563                         exit(1);
 564                 if (--cnt < 0)
 565                         fatal(STDOUT_FILENO, errmsg, 0);
 566                 *buf++ = c;
 567         } while (c != 0);
 568 }
 569
 570 void
 571 setup_term(int fd)
 572 {
 573         register char *cp = index(term+ENVSIZE, '/');
 574         char *speed;
 575         struct termios tt;
 576
 577 #ifndef notyet
 578         tcgetattr(fd, &tt);
 579         if (cp) {
 580                 *cp++ = '\0';
 581                 speed = cp;
 582                 cp = index(speed, '/');
 583                 if (cp)
 584                         *cp++ = '\0';
 585                 cfsetspeed(&tt, atoi(speed));
 586         }
 587
 588         tt.c_iflag = TTYDEF_IFLAG;
 589         tt.c_oflag = TTYDEF_OFLAG;
 590         tt.c_lflag = TTYDEF_LFLAG;
 591         tcsetattr(fd, TCSAFLUSH, &tt);
 592 #else
 593         if (cp) {
 594                 *cp++ = '\0';
 595                 speed = cp;
 596                 cp = index(speed, '/');
 597                 if (cp)
 598                         *cp++ = '\0';
 599                 tcgetattr(fd, &tt);
 600                 cfsetspeed(&tt, atoi(speed));
 601                 tcsetattr(fd, TCSAFLUSH, &tt);
 602         }
 603 #endif
 604
 605         env[0] = term;
 606         env[1] = NULL;
 607         environ = env;
 608 }
 609
 610 void
 611 usage(void)
 612 {
 613         syslog(LOG_ERR, "usage: rlogind [-" ARGSTR "]");
 614 }