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  * $DragonFly: src/libexec/rlogind/rlogind.c,v 1.5 2007/05/18 17:05:12 dillon Exp $
  37  */
  38
  39 /*
  40  * remote login server:
  41  *      \0
  42  *      remuser\0
  43  *      locuser\0
  44  *      terminal_type/speed\0
  45  *      data
  46  */
  47
  48 #define FD_SETSIZE      16              /* don't need many bits for select */
  49 #include <sys/types.h>
  50 #include <sys/param.h>
  51 #include <sys/stat.h>
  52 #include <sys/ioctl.h>
  53 #include <signal.h>
  54 #include <termios.h>
  55
  56 #include <sys/socket.h>
  57 #include <netinet/in.h>
  58 #include <netinet/in_systm.h>
  59 #include <netinet/ip.h>
  60 #include <netinet/tcp.h>
  61 #include <arpa/inet.h>
  62 #include <netdb.h>
  63
  64 #include <errno.h>
  65 #include <libutil.h>
  66 #include <pwd.h>
  67 #include <syslog.h>
  68 #include <stdio.h>
  69 #include <stdlib.h>
  70 #include <string.h>
  71 #include <unistd.h>
  72 #include "pathnames.h"
  73
  74
  75 #ifndef TIOCPKT_WINDOW
  76 #define TIOCPKT_WINDOW 0x80
  77 #endif
  78
  79 #define         ARGSTR                  "Dalnx"
  80
  81 /* wrapper for KAME-special getnameinfo() */
  82 #ifndef NI_WITHSCOPEID
  83 #define NI_WITHSCOPEID  0
  84 #endif
  85
  86 extern int __check_rhosts_file;
  87 extern  char **environ;
  88
  89 char    *env[2];
  90 #define NMAX 30
  91 char    lusername[NMAX+1], rusername[NMAX+1];
  92 static  char term[64] = "TERM=";
  93 #define ENVSIZE (sizeof("TERM=")-1)     /* skip null for concatenation */
  94 int     keepalive = 1;
  95 int     check_all = 0;
  96 int     no_delay;
  97
  98 struct  passwd *pwd;
  99
 100 union sockunion {
 101         struct sockinet {
 102                 u_char si_len;
 103                 u_char si_family;
 104                 u_short si_port;
 105         } su_si;
 106         struct sockaddr_in  su_sin;
 107         struct sockaddr_in6 su_sin6;
 108 };
 109 #define su_len          su_si.si_len
 110 #define su_family       su_si.si_family
 111 #define su_port         su_si.si_port
 112
 113 void    doit(int, union sockunion *);
 114 int     control(int, char *, int);
 115 void    protocol(int, int);
 116 void    cleanup(int);
 117 void    fatal(int, const char *, int);
 118 int     do_rlogin(union sockunion *);
 119 void    getstr(char *, int, const char *);
 120 void    setup_term(int);
 121 int     do_krb_login(struct sockaddr_in *);
 122 void    usage(void);
 123
 124
 125 int
 126 main(int argc, char *argv[])
 127 {
 128         union sockunion from;
 129         socklen_t fromlen;
 130         int ch, on;
 131
 132         openlog("rlogind", LOG_PID | LOG_CONS, LOG_AUTH);
 133
 134         opterr = 0;
 135         while ((ch = getopt(argc, argv, ARGSTR)) != -1)
 136                 switch (ch) {
 137                 case 'D':
 138                         no_delay = 1;
 139                         break;
 140                 case 'a':
 141                         check_all = 1;
 142                         break;
 143                 case 'l':
 144                         __check_rhosts_file = 0;
 145                         break;
 146                 case 'n':
 147                         keepalive = 0;
 148                         break;
 149 #ifdef CRYPT
 150                 case 'x':
 151                         doencrypt = 1;
 152                         break;
 153 #endif
 154                 case '?':
 155                 default:
 156                         usage();
 157                         break;
 158                 }
 159         argc -= optind;
 160         argv += optind;
 161
 162         fromlen = sizeof (from);
 163         if (getpeername(0, (struct sockaddr *)&from, &fromlen) < 0) {
 164                 syslog(LOG_ERR,"Can't get peer name of remote host: %m");
 165                 fatal(STDERR_FILENO, "Can't get peer name of remote host", 1);
 166         }
 167         on = 1;
 168         if (keepalive &&
 169             setsockopt(0, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof (on)) < 0)
 170                 syslog(LOG_WARNING, "setsockopt (SO_KEEPALIVE): %m");
 171         if (no_delay &&
 172             setsockopt(0, IPPROTO_TCP, TCP_NODELAY, &on, sizeof(on)) < 0)
 173                 syslog(LOG_WARNING, "setsockopt (TCP_NODELAY): %m");
 174         if (from.su_family == AF_INET)
 175       {
 176         on = IPTOS_LOWDELAY;
 177         if (setsockopt(0, IPPROTO_IP, IP_TOS, (char *)&on, sizeof(int)) < 0)
 178                 syslog(LOG_WARNING, "setsockopt (IP_TOS): %m");
 179       }
 180
 181         doit(0, &from);
 182         return 0;
 183 }
 184
 185 int     child;
 186 int     netf;
 187 char    line[MAXPATHLEN];
 188 int     confirmed;
 189
 190 struct winsize win = { 0, 0, 0, 0 };
 191
 192
 193 void
 194 doit(int f, union sockunion *fromp)
 195 {
 196         int master, pid, on = 1;
 197         int authenticated = 0;
 198         char hostname[2 * MAXHOSTNAMELEN + 1];
 199         char nameinfo[2 * INET6_ADDRSTRLEN + 1];
 200         u_char c;
 201
 202         alarm(60);
 203         read(f, &c, 1);
 204
 205         if (c != 0)
 206                 exit(1);
 207
 208         alarm(0);
 209
 210         realhostname_sa(hostname, sizeof(hostname) - 1,
 211                             (struct sockaddr *)fromp, fromp->su_len);
 212         /* error check ? */
 213         fromp->su_port = ntohs((u_short)fromp->su_port);
 214         hostname[sizeof(hostname) - 1] = '\0';
 215
 216         {
 217                 if ((fromp->su_family != AF_INET
 218 #ifdef INET6
 219                   && fromp->su_family != AF_INET6
 220 #endif
 221                      ) ||
 222                     fromp->su_port >= IPPORT_RESERVED ||
 223                     fromp->su_port < IPPORT_RESERVED/2) {
 224                         getnameinfo((struct sockaddr *)fromp,
 225                                     fromp->su_len,
 226                                     nameinfo, sizeof(nameinfo), NULL, 0,
 227                                     NI_NUMERICHOST|NI_WITHSCOPEID);
 228                         /* error check ? */
 229                         syslog(LOG_NOTICE, "Connection from %s on illegal port",
 230                                nameinfo);
 231                         fatal(f, "Permission denied", 0);
 232                 }
 233 #ifdef IP_OPTIONS
 234                 if (fromp->su_family == AF_INET)
 235               {
 236                 u_char optbuf[BUFSIZ/3];
 237                 socklen_t optsize = sizeof(optbuf), i;
 238                 int ipproto;
 239                 struct protoent *ip;
 240
 241                 if ((ip = getprotobyname("ip")) != NULL)
 242                         ipproto = ip->p_proto;
 243                 else
 244                         ipproto = IPPROTO_IP;
 245                 if (getsockopt(0, ipproto, IP_OPTIONS, (char *)optbuf,
 246                     &optsize) == 0 && optsize != 0) {
 247                         for (i = 0; i < optsize; ) {
 248                                 c = optbuf[i];
 249                                 if (c == IPOPT_LSRR || c == IPOPT_SSRR) {
 250                                         syslog(LOG_NOTICE,
 251                                                 "Connection refused from %s with IP option %s",
 252                                                 inet_ntoa(fromp->su_sin.sin_addr),
 253                                                 c == IPOPT_LSRR ? "LSRR" : "SSRR");
 254                                         exit(1);
 255                                 }
 256                                 if (c == IPOPT_EOL)
 257                                         break;
 258                                 i += (c == IPOPT_NOP) ? 1 : optbuf[i+1];
 259                         }
 260                 }
 261               }
 262 #endif
 263                 if (do_rlogin(fromp) == 0)
 264                         authenticated++;
 265         }
 266         if (confirmed == 0) {
 267                 write(f, "", 1);
 268                 confirmed = 1;          /* we sent the null! */
 269         }
 270 #ifdef  CRYPT
 271         if (doencrypt) {
 272                 des_enc_write(f, SECURE_MESSAGE, strlen(SECURE_MESSAGE),
 273                     schedule, &kdata->session);
 274         }
 275 #endif
 276         netf = f;
 277
 278         pid = forkpty(&master, line, NULL, &win);
 279         if (pid < 0) {
 280                 if (errno == ENOENT)
 281                         fatal(f, "Out of ptys", 0);
 282                 else
 283                         fatal(f, "Forkpty", 1);
 284         }
 285         if (pid == 0) {
 286                 if (f > 2)      /* f should always be 0, but... */
 287                         close(f);
 288                 setup_term(0);
 289                  if (*lusername=='-') {
 290                         syslog(LOG_ERR, "tried to pass user \"%s\" to login",
 291                                lusername);
 292                         fatal(STDERR_FILENO, "invalid user", 0);
 293                 }
 294                 if (authenticated) {
 295                         execl(_PATH_LOGIN, "login", "-p",
 296                             "-h", hostname, "-f", lusername, NULL);
 297                 } else
 298                         execl(_PATH_LOGIN, "login", "-p",
 299                             "-h", hostname, lusername, NULL);
 300                 fatal(STDERR_FILENO, _PATH_LOGIN, 1);
 301                 /*NOTREACHED*/
 302         }
 303 #ifdef  CRYPT
 304         /*
 305          * If encrypted, don't turn on NBIO or the des read/write
 306          * routines will croak.
 307          */
 308
 309         if (!doencrypt)
 310 #endif
 311                 ioctl(f, FIONBIO, &on);
 312         ioctl(master, FIONBIO, &on);
 313         ioctl(master, TIOCPKT, &on);
 314         signal(SIGCHLD, cleanup);
 315         protocol(f, master);
 316         signal(SIGCHLD, SIG_IGN);
 317         cleanup(0);
 318 }
 319
 320 char    magic[2] = { 0377, 0377 };
 321 char    oobdata[] = {TIOCPKT_WINDOW};
 322
 323 /*
 324  * Handle a "control" request (signaled by magic being present)
 325  * in the data stream.  For now, we are only willing to handle
 326  * window size changes.
 327  */
 328 int
 329 control(int pty, char *cp, int n)
 330 {
 331         struct winsize w;
 332
 333         if (n < 4 + (int)sizeof(w) || cp[2] != 's' || cp[3] != 's')
 334                 return (0);
 335         oobdata[0] &= ~TIOCPKT_WINDOW;  /* we know he heard */
 336         bcopy(cp+4, (char *)&w, sizeof(w));
 337         w.ws_row = ntohs(w.ws_row);
 338         w.ws_col = ntohs(w.ws_col);
 339         w.ws_xpixel = ntohs(w.ws_xpixel);
 340         w.ws_ypixel = ntohs(w.ws_ypixel);
 341         ioctl(pty, TIOCSWINSZ, &w);
 342         return (4+sizeof (w));
 343 }
 344
 345 /*
 346  * rlogin "protocol" machine.
 347  */
 348 void
 349 protocol(int f, int p)
 350 {
 351         char pibuf[1024+1], fibuf[1024], *pbp = NULL, *fbp = NULL;
 352         int pcc = 0, fcc = 0;
 353         int cc, nfd, n;
 354         char cntl;
 355
 356         /*
 357          * Must ignore SIGTTOU, otherwise we'll stop
 358          * when we try and set slave pty's window shape
 359          * (our controlling tty is the master pty).
 360          */
 361         signal(SIGTTOU, SIG_IGN);
 362         send(f, oobdata, 1, MSG_OOB);   /* indicate new rlogin */
 363         if (f > p)
 364                 nfd = f + 1;
 365         else
 366                 nfd = p + 1;
 367         if (nfd > FD_SETSIZE) {
 368                 syslog(LOG_ERR, "select mask too small, increase FD_SETSIZE");
 369                 fatal(f, "internal error (select mask too small)", 0);
 370         }
 371         for (;;) {
 372                 fd_set ibits, obits, ebits, *omask;
 373
 374                 FD_ZERO(&ebits);
 375                 FD_ZERO(&ibits);
 376                 FD_ZERO(&obits);
 377                 omask = NULL;
 378                 if (fcc) {
 379                         FD_SET(p, &obits);
 380                         omask = &obits;
 381                 } else
 382                         FD_SET(f, &ibits);
 383                 if (pcc >= 0) {
 384                         if (pcc) {
 385                                 FD_SET(f, &obits);
 386                                 omask = &obits;
 387                         } else
 388                                 FD_SET(p, &ibits);
 389                 }
 390                 FD_SET(p, &ebits);
 391                 if ((n = select(nfd, &ibits, omask, &ebits, 0)) < 0) {
 392                         if (errno == EINTR)
 393                                 continue;
 394                         fatal(f, "select", 1);
 395                 }
 396                 if (n == 0) {
 397                         /* shouldn't happen... */
 398                         sleep(5);
 399                         continue;
 400                 }
 401 #define pkcontrol(c)    ((c)&(TIOCPKT_FLUSHWRITE|TIOCPKT_NOSTOP|TIOCPKT_DOSTOP))
 402                 if (FD_ISSET(p, &ebits)) {
 403                         cc = read(p, &cntl, 1);
 404                         if (cc == 1 && pkcontrol(cntl)) {
 405                                 cntl |= oobdata[0];
 406                                 send(f, &cntl, 1, MSG_OOB);
 407                                 if (cntl & TIOCPKT_FLUSHWRITE) {
 408                                         pcc = 0;
 409                                         FD_CLR(p, &ibits);
 410                                 }
 411                         }
 412                 }
 413                 if (FD_ISSET(f, &ibits)) {
 414 #ifdef  CRYPT
 415                         if (doencrypt)
 416                                 fcc = des_enc_read(f, fibuf, sizeof(fibuf),
 417                                         schedule, &kdata->session);
 418                         else
 419 #endif
 420                                 fcc = read(f, fibuf, sizeof(fibuf));
 421                         if (fcc < 0 && errno == EWOULDBLOCK)
 422                                 fcc = 0;
 423                         else {
 424                                 register char *cp;
 425                                 int left;
 426
 427                                 if (fcc <= 0)
 428                                         break;
 429                                 fbp = fibuf;
 430
 431                         top:
 432                                 for (cp = fibuf; cp < fibuf+fcc-1; cp++)
 433                                         if (cp[0] == magic[0] &&
 434                                             cp[1] == magic[1]) {
 435                                                 left = fcc - (cp-fibuf);
 436                                                 n = control(p, cp, left);
 437                                                 if (n) {
 438                                                         left -= n;
 439                                                         if (left > 0)
 440                                                                 bcopy(cp+n, cp, left);
 441                                                         fcc -= n;
 442                                                         goto top; /* n^2 */
 443                                                 }
 444                                         }
 445                                 FD_SET(p, &obits);              /* try write */
 446                         }
 447                 }
 448
 449                 if (FD_ISSET(p, &obits) && fcc > 0) {
 450                         cc = write(p, fbp, fcc);
 451                         if (cc > 0) {
 452                                 fcc -= cc;
 453                                 fbp += cc;
 454                         }
 455                 }
 456
 457                 if (FD_ISSET(p, &ibits)) {
 458                         pcc = read(p, pibuf, sizeof (pibuf));
 459                         pbp = pibuf;
 460                         if (pcc < 0 && errno == EWOULDBLOCK)
 461                                 pcc = 0;
 462                         else if (pcc <= 0)
 463                                 break;
 464                         else if (pibuf[0] == 0) {
 465                                 pbp++, pcc--;
 466 #ifdef  CRYPT
 467                                 if (!doencrypt)
 468 #endif
 469                                         FD_SET(f, &obits);      /* try write */
 470                         } else {
 471                                 if (pkcontrol(pibuf[0])) {
 472                                         pibuf[0] |= oobdata[0];
 473                                         send(f, &pibuf[0], 1, MSG_OOB);
 474                                 }
 475                                 pcc = 0;
 476                         }
 477                 }
 478                 if ((FD_ISSET(f, &obits)) && pcc > 0) {
 479 #ifdef  CRYPT
 480                         if (doencrypt)
 481                                 cc = des_enc_write(f, pbp, pcc,
 482                                         schedule, &kdata->session);
 483                         else
 484 #endif
 485                                 cc = write(f, pbp, pcc);
 486                         if (cc < 0 && errno == EWOULDBLOCK) {
 487                                 /*
 488                                  * This happens when we try write after read
 489                                  * from p, but some old kernels balk at large
 490                                  * writes even when select returns true.
 491                                  */
 492                                 if (!FD_ISSET(p, &ibits))
 493                                         sleep(5);
 494                                 continue;
 495                         }
 496                         if (cc > 0) {
 497                                 pcc -= cc;
 498                                 pbp += cc;
 499                         }
 500                 }
 501         }
 502 }
 503
 504 void
 505 cleanup(int signo __unused)
 506 {
 507         char *p;
 508
 509         p = line + sizeof(_PATH_DEV) - 1;
 510         if (logout(p))
 511                 logwtmp(p, "", "");
 512         chflags(line, 0);
 513         chmod(line, 0666);
 514         chown(line, 0, 0);
 515         *p = 'p';
 516         chflags(line, 0);
 517         chmod(line, 0666);
 518         chown(line, 0, 0);
 519         shutdown(netf, SHUT_RDWR);
 520         exit(1);
 521 }
 522
 523 void
 524 fatal(int f, const char *msg, int syserr)
 525 {
 526         int len;
 527         char buf[BUFSIZ], *bp = buf;
 528
 529         /*
 530          * Prepend binary one to message if we haven't sent
 531          * the magic null as confirmation.
 532          */
 533         if (!confirmed)
 534                 *bp++ = '\01';          /* error indicator */
 535         if (syserr)
 536                 len = snprintf(bp, sizeof(buf), "rlogind: %s: %s.\r\n",
 537                     msg, strerror(errno));
 538         else
 539                 len = snprintf(bp, sizeof(buf), "rlogind: %s.\r\n", msg);
 540         write(f, buf, bp + len - buf);
 541         exit(1);
 542 }
 543
 544 int
 545 do_rlogin(union sockunion *dest)
 546 {
 547
 548         getstr(rusername, sizeof(rusername), "remuser too long");
 549         getstr(lusername, sizeof(lusername), "locuser too long");
 550         getstr(term+ENVSIZE, sizeof(term)-ENVSIZE, "Terminal type too long");
 551
 552         pwd = getpwnam(lusername);
 553         if (pwd == NULL)
 554                 return (-1);
 555         /* XXX why don't we syslog() failure? */
 556
 557         return (iruserok_sa(dest, dest->su_len, pwd->pw_uid == 0, rusername,
 558                             lusername));
 559 }
 560
 561 void
 562 getstr(char *buf, int cnt, const char *errmsg)
 563 {
 564         char c;
 565
 566         do {
 567                 if (read(0, &c, 1) != 1)
 568                         exit(1);
 569                 if (--cnt < 0)
 570                         fatal(STDOUT_FILENO, errmsg, 0);
 571                 *buf++ = c;
 572         } while (c != 0);
 573 }
 574
 575 void
 576 setup_term(int fd)
 577 {
 578         register char *cp = index(term+ENVSIZE, '/');
 579         char *speed;
 580         struct termios tt;
 581
 582 #ifndef notyet
 583         tcgetattr(fd, &tt);
 584         if (cp) {
 585                 *cp++ = '\0';
 586                 speed = cp;
 587                 cp = index(speed, '/');
 588                 if (cp)
 589                         *cp++ = '\0';
 590                 cfsetspeed(&tt, atoi(speed));
 591         }
 592
 593         tt.c_iflag = TTYDEF_IFLAG;
 594         tt.c_oflag = TTYDEF_OFLAG;
 595         tt.c_lflag = TTYDEF_LFLAG;
 596         tcsetattr(fd, TCSAFLUSH, &tt);
 597 #else
 598         if (cp) {
 599                 *cp++ = '\0';
 600                 speed = cp;
 601                 cp = index(speed, '/');
 602                 if (cp)
 603                         *cp++ = '\0';
 604                 tcgetattr(fd, &tt);
 605                 cfsetspeed(&tt, atoi(speed));
 606                 tcsetattr(fd, TCSAFLUSH, &tt);
 607         }
 608 #endif
 609
 610         env[0] = term;
 611         env[1] = 0;
 612         environ = env;
 613 }
 614
 615 void
 616 usage(void)
 617 {
 618         syslog(LOG_ERR, "usage: rlogind [-" ARGSTR "]");
 619 }