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. 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) 1983, 1988, 1989, 1993 The Regents of the University of California.  All rights reserved.
  34  * @(#)rlogind.c        8.1 (Berkeley) 6/4/93
  35  * $FreeBSD: src/libexec/rlogind/rlogind.c,v 1.29.2.5 2000/12/07 15:02:31 ru Exp $
  36  */
  37
  38 /*
  39  * remote login server:
  40  *      \0
  41  *      remuser\0
  42  *      locuser\0
  43  *      terminal_type/speed\0
  44  *      data
  45  */
  46
  47 #define FD_SETSIZE      16              /* don't need many bits for select */
  48 #include <sys/types.h>
  49 #include <sys/param.h>
  50 #include <sys/stat.h>
  51 #include <sys/ioctl.h>
  52 #include <signal.h>
  53 #include <termios.h>
  54
  55 #include <sys/socket.h>
  56 #include <netinet/in.h>
  57 #include <netinet/in_systm.h>
  58 #include <netinet/ip.h>
  59 #include <netinet/tcp.h>
  60 #include <arpa/inet.h>
  61 #include <netdb.h>
  62
  63 #include <errno.h>
  64 #include <libutil.h>
  65 #include <pwd.h>
  66 #include <syslog.h>
  67 #include <stdio.h>
  68 #include <stdlib.h>
  69 #include <string.h>
  70 #include <unistd.h>
  71 #include "pathnames.h"
  72
  73
  74 #ifndef TIOCPKT_WINDOW
  75 #define TIOCPKT_WINDOW 0x80
  76 #endif
  77
  78 #define         ARGSTR                  "Dalnx"
  79
  80 /* wrapper for KAME-special getnameinfo() */
  81 #ifndef NI_WITHSCOPEID
  82 #define NI_WITHSCOPEID  0
  83 #endif
  84
  85 extern int __check_rhosts_file;
  86 extern  char **environ;
  87
  88 char    *env[2];
  89 #define NMAX 30
  90 char    lusername[NMAX+1], rusername[NMAX+1];
  91 static  char term[64] = "TERM=";
  92 #define ENVSIZE (sizeof("TERM=")-1)     /* skip null for concatenation */
  93 int     keepalive = 1;
  94 int     check_all = 0;
  95 int     no_delay;
  96
  97 struct  passwd *pwd;
  98
  99 union sockunion {
 100         struct sockinet {
 101                 u_char si_len;
 102                 u_char si_family;
 103                 u_short si_port;
 104         } su_si;
 105         struct sockaddr_in  su_sin;
 106         struct sockaddr_in6 su_sin6;
 107 };
 108 #define su_len          su_si.si_len
 109 #define su_family       su_si.si_family
 110 #define su_port         su_si.si_port
 111
 112 void    doit(int, union sockunion *);
 113 int     control(int, char *, int);
 114 void    protocol(int, int);
 115 void    cleanup(int);
 116 void    fatal(int, const char *, int);
 117 int     do_rlogin(union sockunion *);
 118 void    getstr(char *, int, const char *);
 119 void    setup_term(int);
 120 int     do_krb_login(struct sockaddr_in *);
 121 void    usage(void);
 122
 123
 124 int
 125 main(int argc, char *argv[])
 126 {
 127         union sockunion from;
 128         socklen_t fromlen;
 129         int ch, on;
 130
 131         openlog("rlogind", LOG_PID | LOG_CONS, LOG_AUTH);
 132
 133         opterr = 0;
 134         while ((ch = getopt(argc, argv, ARGSTR)) != -1)
 135                 switch (ch) {
 136                 case 'D':
 137                         no_delay = 1;
 138                         break;
 139                 case 'a':
 140                         check_all = 1;
 141                         break;
 142                 case 'l':
 143                         __check_rhosts_file = 0;
 144                         break;
 145                 case 'n':
 146                         keepalive = 0;
 147                         break;
 148 #ifdef CRYPT
 149                 case 'x':
 150                         doencrypt = 1;
 151                         break;
 152 #endif
 153                 case '?':
 154                 default:
 155                         usage();
 156                         break;
 157                 }
 158         argc -= optind;
 159         argv += optind;
 160
 161         fromlen = sizeof (from);
 162         if (getpeername(0, (struct sockaddr *)&from, &fromlen) < 0) {
 163                 syslog(LOG_ERR,"Can't get peer name of remote host: %m");
 164                 fatal(STDERR_FILENO, "Can't get peer name of remote host", 1);
 165         }
 166         on = 1;
 167         if (keepalive &&
 168             setsockopt(0, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof (on)) < 0)
 169                 syslog(LOG_WARNING, "setsockopt (SO_KEEPALIVE): %m");
 170         if (no_delay &&
 171             setsockopt(0, IPPROTO_TCP, TCP_NODELAY, &on, sizeof(on)) < 0)
 172                 syslog(LOG_WARNING, "setsockopt (TCP_NODELAY): %m");
 173         if (from.su_family == AF_INET)
 174       {
 175         on = IPTOS_LOWDELAY;
 176         if (setsockopt(0, IPPROTO_IP, IP_TOS, (char *)&on, sizeof(int)) < 0)
 177                 syslog(LOG_WARNING, "setsockopt (IP_TOS): %m");
 178       }
 179
 180         doit(0, &from);
 181         return 0;
 182 }
 183
 184 int     child;
 185 int     netf;
 186 char    line[MAXPATHLEN];
 187 int     confirmed;
 188
 189 struct winsize win = { 0, 0, 0, 0 };
 190
 191
 192 void
 193 doit(int f, union sockunion *fromp)
 194 {
 195         int master, pid, on = 1;
 196         int authenticated = 0;
 197         char hostname[2 * MAXHOSTNAMELEN + 1];
 198         char nameinfo[2 * INET6_ADDRSTRLEN + 1];
 199         u_char c;
 200
 201         alarm(60);
 202         read(f, &c, 1);
 203
 204         if (c != 0)
 205                 exit(1);
 206
 207         alarm(0);
 208
 209         realhostname_sa(hostname, sizeof(hostname) - 1,
 210                             (struct sockaddr *)fromp, fromp->su_len);
 211         /* error check ? */
 212         fromp->su_port = ntohs((u_short)fromp->su_port);
 213         hostname[sizeof(hostname) - 1] = '\0';
 214
 215         {
 216                 if ((fromp->su_family != AF_INET
 217 #ifdef INET6
 218                   && fromp->su_family != AF_INET6
 219 #endif
 220                      ) ||
 221                     fromp->su_port >= IPPORT_RESERVED ||
 222                     fromp->su_port < IPPORT_RESERVED/2) {
 223                         getnameinfo((struct sockaddr *)fromp,
 224                                     fromp->su_len,
 225                                     nameinfo, sizeof(nameinfo), NULL, 0,
 226                                     NI_NUMERICHOST|NI_WITHSCOPEID);
 227                         /* error check ? */
 228                         syslog(LOG_NOTICE, "Connection from %s on illegal port",
 229                                nameinfo);
 230                         fatal(f, "Permission denied", 0);
 231                 }
 232 #ifdef IP_OPTIONS
 233                 if (fromp->su_family == AF_INET)
 234               {
 235                 u_char optbuf[BUFSIZ/3];
 236                 socklen_t optsize = sizeof(optbuf), i;
 237                 int ipproto;
 238                 struct protoent *ip;
 239
 240                 if ((ip = getprotobyname("ip")) != NULL)
 241                         ipproto = ip->p_proto;
 242                 else
 243                         ipproto = IPPROTO_IP;
 244                 if (getsockopt(0, ipproto, IP_OPTIONS, (char *)optbuf,
 245                     &optsize) == 0 && optsize != 0) {
 246                         for (i = 0; i < optsize; ) {
 247                                 c = optbuf[i];
 248                                 if (c == IPOPT_LSRR || c == IPOPT_SSRR) {
 249                                         syslog(LOG_NOTICE,
 250                                                 "Connection refused from %s with IP option %s",
 251                                                 inet_ntoa(fromp->su_sin.sin_addr),
 252                                                 c == IPOPT_LSRR ? "LSRR" : "SSRR");
 253                                         exit(1);
 254                                 }
 255                                 if (c == IPOPT_EOL)
 256                                         break;
 257                                 i += (c == IPOPT_NOP) ? 1 : optbuf[i+1];
 258                         }
 259                 }
 260               }
 261 #endif
 262                 if (do_rlogin(fromp) == 0)
 263                         authenticated++;
 264         }
 265         if (confirmed == 0) {
 266                 write(f, "", 1);
 267                 confirmed = 1;          /* we sent the null! */
 268         }
 269 #ifdef  CRYPT
 270         if (doencrypt) {
 271                 des_enc_write(f, SECURE_MESSAGE, strlen(SECURE_MESSAGE),
 272                     schedule, &kdata->session);
 273         }
 274 #endif
 275         netf = f;
 276
 277         pid = forkpty(&master, line, NULL, &win);
 278         if (pid < 0) {
 279                 if (errno == ENOENT)
 280                         fatal(f, "Out of ptys", 0);
 281                 else
 282                         fatal(f, "Forkpty", 1);
 283         }
 284         if (pid == 0) {
 285                 if (f > 2)      /* f should always be 0, but... */
 286                         close(f);
 287                 setup_term(0);
 288                  if (*lusername=='-') {
 289                         syslog(LOG_ERR, "tried to pass user \"%s\" to login",
 290                                lusername);
 291                         fatal(STDERR_FILENO, "invalid user", 0);
 292                 }
 293                 if (authenticated) {
 294                         execl(_PATH_LOGIN, "login", "-p",
 295                             "-h", hostname, "-f", lusername, NULL);
 296                 } else
 297                         execl(_PATH_LOGIN, "login", "-p",
 298                             "-h", hostname, lusername, NULL);
 299                 fatal(STDERR_FILENO, _PATH_LOGIN, 1);
 300                 /*NOTREACHED*/
 301         }
 302 #ifdef  CRYPT
 303         /*
 304          * If encrypted, don't turn on NBIO or the des read/write
 305          * routines will croak.
 306          */
 307
 308         if (!doencrypt)
 309 #endif
 310                 ioctl(f, FIONBIO, &on);
 311         ioctl(master, FIONBIO, &on);
 312         ioctl(master, TIOCPKT, &on);
 313         signal(SIGCHLD, cleanup);
 314         protocol(f, master);
 315         signal(SIGCHLD, SIG_IGN);
 316         cleanup(0);
 317 }
 318
 319 char    magic[2] = { 0377, 0377 };
 320 char    oobdata[] = {TIOCPKT_WINDOW};
 321
 322 /*
 323  * Handle a "control" request (signaled by magic being present)
 324  * in the data stream.  For now, we are only willing to handle
 325  * window size changes.
 326  */
 327 int
 328 control(int pty, char *cp, int n)
 329 {
 330         struct winsize w;
 331
 332         if (n < 4 + (int)sizeof(w) || cp[2] != 's' || cp[3] != 's')
 333                 return (0);
 334         oobdata[0] &= ~TIOCPKT_WINDOW;  /* we know he heard */
 335         bcopy(cp+4, (char *)&w, sizeof(w));
 336         w.ws_row = ntohs(w.ws_row);
 337         w.ws_col = ntohs(w.ws_col);
 338         w.ws_xpixel = ntohs(w.ws_xpixel);
 339         w.ws_ypixel = ntohs(w.ws_ypixel);
 340         ioctl(pty, TIOCSWINSZ, &w);
 341         return (4+sizeof (w));
 342 }
 343
 344 /*
 345  * rlogin "protocol" machine.
 346  */
 347 void
 348 protocol(int f, int p)
 349 {
 350         char pibuf[1024+1], fibuf[1024], *pbp = NULL, *fbp = NULL;
 351         int pcc = 0, fcc = 0;
 352         int cc, nfd, n;
 353         char cntl;
 354
 355         /*
 356          * Must ignore SIGTTOU, otherwise we'll stop
 357          * when we try and set slave pty's window shape
 358          * (our controlling tty is the master pty).
 359          */
 360         signal(SIGTTOU, SIG_IGN);
 361         send(f, oobdata, 1, MSG_OOB);   /* indicate new rlogin */
 362         if (f > p)
 363                 nfd = f + 1;
 364         else
 365                 nfd = p + 1;
 366         if (nfd > FD_SETSIZE) {
 367                 syslog(LOG_ERR, "select mask too small, increase FD_SETSIZE");
 368                 fatal(f, "internal error (select mask too small)", 0);
 369         }
 370         for (;;) {
 371                 fd_set ibits, obits, ebits, *omask;
 372
 373                 FD_ZERO(&ebits);
 374                 FD_ZERO(&ibits);
 375                 FD_ZERO(&obits);
 376                 omask = NULL;
 377                 if (fcc) {
 378                         FD_SET(p, &obits);
 379                         omask = &obits;
 380                 } else
 381                         FD_SET(f, &ibits);
 382                 if (pcc >= 0) {
 383                         if (pcc) {
 384                                 FD_SET(f, &obits);
 385                                 omask = &obits;
 386                         } else
 387                                 FD_SET(p, &ibits);
 388                 }
 389                 FD_SET(p, &ebits);
 390                 if ((n = select(nfd, &ibits, omask, &ebits, 0)) < 0) {
 391                         if (errno == EINTR)
 392                                 continue;
 393                         fatal(f, "select", 1);
 394                 }
 395                 if (n == 0) {
 396                         /* shouldn't happen... */
 397                         sleep(5);
 398                         continue;
 399                 }
 400 #define pkcontrol(c)    ((c)&(TIOCPKT_FLUSHWRITE|TIOCPKT_NOSTOP|TIOCPKT_DOSTOP))
 401                 if (FD_ISSET(p, &ebits)) {
 402                         cc = read(p, &cntl, 1);
 403                         if (cc == 1 && pkcontrol(cntl)) {
 404                                 cntl |= oobdata[0];
 405                                 send(f, &cntl, 1, MSG_OOB);
 406                                 if (cntl & TIOCPKT_FLUSHWRITE) {
 407                                         pcc = 0;
 408                                         FD_CLR(p, &ibits);
 409                                 }
 410                         }
 411                 }
 412                 if (FD_ISSET(f, &ibits)) {
 413 #ifdef  CRYPT
 414                         if (doencrypt)
 415                                 fcc = des_enc_read(f, fibuf, sizeof(fibuf),
 416                                         schedule, &kdata->session);
 417                         else
 418 #endif
 419                                 fcc = read(f, fibuf, sizeof(fibuf));
 420                         if (fcc < 0 && errno == EWOULDBLOCK)
 421                                 fcc = 0;
 422                         else {
 423                                 register char *cp;
 424                                 int left;
 425
 426                                 if (fcc <= 0)
 427                                         break;
 428                                 fbp = fibuf;
 429
 430                         top:
 431                                 for (cp = fibuf; cp < fibuf+fcc-1; cp++)
 432                                         if (cp[0] == magic[0] &&
 433                                             cp[1] == magic[1]) {
 434                                                 left = fcc - (cp-fibuf);
 435                                                 n = control(p, cp, left);
 436                                                 if (n) {
 437                                                         left -= n;
 438                                                         if (left > 0)
 439                                                                 bcopy(cp+n, cp, left);
 440                                                         fcc -= n;
 441                                                         goto top; /* n^2 */
 442                                                 }
 443                                         }
 444                                 FD_SET(p, &obits);              /* try write */
 445                         }
 446                 }
 447
 448                 if (FD_ISSET(p, &obits) && fcc > 0) {
 449                         cc = write(p, fbp, fcc);
 450                         if (cc > 0) {
 451                                 fcc -= cc;
 452                                 fbp += cc;
 453                         }
 454                 }
 455
 456                 if (FD_ISSET(p, &ibits)) {
 457                         pcc = read(p, pibuf, sizeof (pibuf));
 458                         pbp = pibuf;
 459                         if (pcc < 0 && errno == EWOULDBLOCK)
 460                                 pcc = 0;
 461                         else if (pcc <= 0)
 462                                 break;
 463                         else if (pibuf[0] == 0) {
 464                                 pbp++, pcc--;
 465 #ifdef  CRYPT
 466                                 if (!doencrypt)
 467 #endif
 468                                         FD_SET(f, &obits);      /* try write */
 469                         } else {
 470                                 if (pkcontrol(pibuf[0])) {
 471                                         pibuf[0] |= oobdata[0];
 472                                         send(f, &pibuf[0], 1, MSG_OOB);
 473                                 }
 474                                 pcc = 0;
 475                         }
 476                 }
 477                 if ((FD_ISSET(f, &obits)) && pcc > 0) {
 478 #ifdef  CRYPT
 479                         if (doencrypt)
 480                                 cc = des_enc_write(f, pbp, pcc,
 481                                         schedule, &kdata->session);
 482                         else
 483 #endif
 484                                 cc = write(f, pbp, pcc);
 485                         if (cc < 0 && errno == EWOULDBLOCK) {
 486                                 /*
 487                                  * This happens when we try write after read
 488                                  * from p, but some old kernels balk at large
 489                                  * writes even when select returns true.
 490                                  */
 491                                 if (!FD_ISSET(p, &ibits))
 492                                         sleep(5);
 493                                 continue;
 494                         }
 495                         if (cc > 0) {
 496                                 pcc -= cc;
 497                                 pbp += cc;
 498                         }
 499                 }
 500         }
 501 }
 502
 503 void
 504 cleanup(int signo __unused)
 505 {
 506         char *p;
 507
 508         p = line + sizeof(_PATH_DEV) - 1;
 509         if (logout(p))
 510                 logwtmp(p, "", "");
 511         chflags(line, 0);
 512         chmod(line, 0666);
 513         chown(line, 0, 0);
 514         *p = 'p';
 515         chflags(line, 0);
 516         chmod(line, 0666);
 517         chown(line, 0, 0);
 518         shutdown(netf, SHUT_RDWR);
 519         exit(1);
 520 }
 521
 522 void
 523 fatal(int f, const char *msg, int syserr)
 524 {
 525         int len;
 526         char buf[BUFSIZ], *bp = buf;
 527
 528         /*
 529          * Prepend binary one to message if we haven't sent
 530          * the magic null as confirmation.
 531          */
 532         if (!confirmed)
 533                 *bp++ = '\01';          /* error indicator */
 534         if (syserr)
 535                 len = snprintf(bp, sizeof(buf), "rlogind: %s: %s.\r\n",
 536                     msg, strerror(errno));
 537         else
 538                 len = snprintf(bp, sizeof(buf), "rlogind: %s.\r\n", msg);
 539         write(f, buf, bp + len - buf);
 540         exit(1);
 541 }
 542
 543 int
 544 do_rlogin(union sockunion *dest)
 545 {
 546
 547         getstr(rusername, sizeof(rusername), "remuser too long");
 548         getstr(lusername, sizeof(lusername), "locuser too long");
 549         getstr(term+ENVSIZE, sizeof(term)-ENVSIZE, "Terminal type too long");
 550
 551         pwd = getpwnam(lusername);
 552         if (pwd == NULL)
 553                 return (-1);
 554         /* XXX why don't we syslog() failure? */
 555
 556         return (iruserok_sa(dest, dest->su_len, pwd->pw_uid == 0, rusername,
 557                             lusername));
 558 }
 559
 560 void
 561 getstr(char *buf, int cnt, const char *errmsg)
 562 {
 563         char c;
 564
 565         do {
 566                 if (read(0, &c, 1) != 1)
 567                         exit(1);
 568                 if (--cnt < 0)
 569                         fatal(STDOUT_FILENO, errmsg, 0);
 570                 *buf++ = c;
 571         } while (c != 0);
 572 }
 573
 574 void
 575 setup_term(int fd)
 576 {
 577         register char *cp = index(term+ENVSIZE, '/');
 578         char *speed;
 579         struct termios tt;
 580
 581 #ifndef notyet
 582         tcgetattr(fd, &tt);
 583         if (cp) {
 584                 *cp++ = '\0';
 585                 speed = cp;
 586                 cp = index(speed, '/');
 587                 if (cp)
 588                         *cp++ = '\0';
 589                 cfsetspeed(&tt, atoi(speed));
 590         }
 591
 592         tt.c_iflag = TTYDEF_IFLAG;
 593         tt.c_oflag = TTYDEF_OFLAG;
 594         tt.c_lflag = TTYDEF_LFLAG;
 595         tcsetattr(fd, TCSAFLUSH, &tt);
 596 #else
 597         if (cp) {
 598                 *cp++ = '\0';
 599                 speed = cp;
 600                 cp = index(speed, '/');
 601                 if (cp)
 602                         *cp++ = '\0';
 603                 tcgetattr(fd, &tt);
 604                 cfsetspeed(&tt, atoi(speed));
 605                 tcsetattr(fd, TCSAFLUSH, &tt);
 606         }
 607 #endif
 608
 609         env[0] = term;
 610         env[1] = NULL;
 611         environ = env;
 612 }
 613
 614 void
 615 usage(void)
 616 {
 617         syslog(LOG_ERR, "usage: rlogind [-" ARGSTR "]");
 618 }