libexec/rshd/rshd.c

   1 /*      $NetBSD: rshd.c,v 1.50 2012/07/14 15:06:26 darrenr Exp $        */
   2
   3 /*
   4  * Copyright (C) 1998 WIDE Project.
   5  * 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. All advertising materials mentioning features or use of this software
  16  *    must display the following acknowledgement:
  17  *    This product includes software developed by WIDE Project and
  18  *    its contributors.
  19  * 4. Neither the name of the project nor the names of its contributors
  20  *    may be used to endorse or promote products derived from this software
  21  *    without specific prior written permission.
  22  *
  23  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
  24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
  27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  33  * SUCH DAMAGE.
  34  */
  35
  36 /*-
  37  * Copyright (c) 1988, 1989, 1992, 1993, 1994
  38  *      The Regents of the University of California.  All rights reserved.
  39  *
  40  * Redistribution and use in source and binary forms, with or without
  41  * modification, are permitted provided that the following conditions
  42  * are met:
  43  * 1. Redistributions of source code must retain the above copyright
  44  *    notice, this list of conditions and the following disclaimer.
  45  * 2. Redistributions in binary form must reproduce the above copyright
  46  *    notice, this list of conditions and the following disclaimer in the
  47  *    documentation and/or other materials provided with the distribution.
  48  * 3. Neither the name of the University nor the names of its contributors
  49  *    may be used to endorse or promote products derived from this software
  50  *    without specific prior written permission.
  51  *
  52  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  53  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  54  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  55  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  56  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  57  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  58  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  59  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  60  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  61  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  62  * SUCH DAMAGE.
  63  */
  64
  65 #include <sys/cdefs.h>
  66 #ifndef lint
  67 __COPYRIGHT("@(#) Copyright (c) 1988, 1989, 1992, 1993, 1994\
  68  The Regents of the University of California.  All rights reserved.");
  69 #if 0
  70 static char sccsid[] = "@(#)rshd.c      8.2 (Berkeley) 4/6/94";
  71 #else
  72 __RCSID("$NetBSD: rshd.c,v 1.50 2012/07/14 15:06:26 darrenr Exp $");
  73 #endif
  74 #endif /* not lint */
  75
  76 /*
  77  * remote shell server:
  78  *      [port]\0
  79  *      remuser\0
  80  *      locuser\0
  81  *      command\0
  82  *      data
  83  */
  84 #include <sys/param.h>
  85 #include <sys/ioctl.h>
  86 #include <sys/time.h>
  87 #include <sys/socket.h>
  88
  89 #include <netinet/in_systm.h>
  90 #include <netinet/in.h>
  91 #include <netinet/ip.h>
  92 #include <netinet/tcp.h>
  93 #include <arpa/inet.h>
  94 #include <netdb.h>
  95
  96 #include <errno.h>
  97 #include <fcntl.h>
  98 #include <paths.h>
  99 #include <pwd.h>
 100 #include <signal.h>
 101 #include <stdio.h>
 102 #include <stdlib.h>
 103 #include <string.h>
 104 #include <syslog.h>
 105 #include <unistd.h>
 106 #include <poll.h>
 107 #ifdef  LOGIN_CAP
 108 #include <login_cap.h>
 109 #endif
 110
 111 #ifdef USE_PAM
 112 #include <security/pam_appl.h>
 113 #include <security/openpam.h>
 114 #include <sys/wait.h>
 115
 116 static struct pam_conv pamc = { openpam_nullconv, NULL };
 117 static pam_handle_t *pamh;
 118 static int pam_err;
 119
 120 #define PAM_END do { \
 121         if ((pam_err = pam_setcred(pamh, PAM_DELETE_CRED)) != PAM_SUCCESS) \
 122                 syslog(LOG_ERR|LOG_AUTH, "pam_setcred(): %s", \
 123                     pam_strerror(pamh, pam_err)); \
 124         if ((pam_err = pam_close_session(pamh,0)) != PAM_SUCCESS) \
 125                 syslog(LOG_ERR|LOG_AUTH, "pam_close_session(): %s", \
 126                     pam_strerror(pamh, pam_err)); \
 127         if ((pam_err = pam_end(pamh, pam_err)) != PAM_SUCCESS) \
 128                 syslog(LOG_ERR|LOG_AUTH, "pam_end(): %s", \
 129                     pam_strerror(pamh, pam_err)); \
 130 } while (/*CONSTCOND*/0)
 131 #else
 132 #define PAM_END
 133 #endif
 134
 135 static int      keepalive = 1;
 136 static int      check_all;
 137 static int      log_success;            /* If TRUE, log all successful accesses */
 138 static int      sent_null;
 139
 140 __dead static void       doit(struct sockaddr *, struct sockaddr *);
 141 __dead static void       rshd_errx(int, const char *, ...) __printflike(2, 3);
 142 static void      getstr(char *, int, const char *);
 143 static int       local_domain(char *);
 144 static char     *topdomain(char *);
 145 __dead static void       usage(void);
 146
 147 #define OPTIONS "aLln"
 148 extern int __check_rhosts_file;
 149 extern char *__rcmd_errstr;     /* syslog hook from libc/net/rcmd.c. */
 150 #if defined(__minix) && defined(USE_PAM)
 151 static const char incorrect[] = "Login incorrect.";
 152 #endif /* defined(__minix) && defined(USE_PAM) */
 153
 154 int
 155 main(int argc, char *argv[])
 156 {
 157         struct linger linger;
 158         int ch, on = 1;
 159         socklen_t fromlen;
 160         socklen_t locallen;
 161         struct sockaddr_storage from;
 162         struct sockaddr_storage local;
 163         struct protoent *proto;
 164
 165         openlog("rshd", LOG_PID, LOG_DAEMON);
 166
 167         opterr = 0;
 168         while ((ch = getopt(argc, argv, OPTIONS)) != -1)
 169                 switch (ch) {
 170                 case 'a':
 171                         check_all = 1;
 172                         break;
 173                 case 'l':
 174                         __check_rhosts_file = 0;
 175                         break;
 176                 case 'n':
 177                         keepalive = 0;
 178                         break;
 179                 case 'L':
 180                         log_success = 1;
 181                         break;
 182                 case '?':
 183                 default:
 184                         usage();
 185                         break;
 186                 }
 187
 188         argc -= optind;
 189         argv += optind;
 190
 191         fromlen = sizeof(from); /* xxx */
 192         locallen = sizeof(local); /* xxx */
 193         if (getpeername(STDIN_FILENO, (struct sockaddr *)&from, &fromlen) < 0) {
 194                 syslog(LOG_ERR, "getpeername: %m");
 195                 return EXIT_FAILURE;
 196         }
 197         if (getsockname(STDIN_FILENO, (struct sockaddr *)&local,
 198             &locallen) < 0) {
 199                 syslog(LOG_ERR, "getsockname: %m");
 200                 return EXIT_FAILURE;
 201         }
 202 #if 0
 203         if (((struct sockaddr *)&from)->sa_family == AF_INET6 &&
 204             IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6 *)&from)->sin6_addr) &&
 205             sizeof(struct sockaddr_in) <= sizeof(from)) {
 206                 struct sockaddr_in sin;
 207                 struct sockaddr_in6 *sin6;
 208                 const int off = sizeof(struct sockaddr_in6) -
 209                     sizeof(struct sockaddr_in);
 210
 211                 sin6 = (struct sockaddr_in6 *)&from;
 212                 (void)memset(&sin, 0, sizeof(sin));
 213                 sin.sin_family = AF_INET;
 214                 sin.sin_len = sizeof(struct sockaddr_in);
 215                 (void)memcpy(&sin.sin_addr, &sin6->sin6_addr.s6_addr[off],
 216                     sizeof(sin.sin_addr));
 217                 (void)memcpy(&from, &sin, sizeof(sin));
 218                 fromlen = sin.sin_len;
 219         }
 220 #else
 221         if (((struct sockaddr *)&from)->sa_family == AF_INET6 &&
 222             IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6 *)&from)->sin6_addr)) {
 223                 char hbuf[NI_MAXHOST];
 224                 if (getnameinfo((struct sockaddr *)&from, fromlen, hbuf,
 225                                 sizeof(hbuf), NULL, 0, NI_NUMERICHOST) != 0) {
 226                         strlcpy(hbuf, "invalid", sizeof(hbuf));
 227                 }
 228                 syslog(LOG_ERR, "malformed \"from\" address (v4 mapped, %s)",
 229                     hbuf);
 230                 return EXIT_FAILURE;
 231         }
 232 #endif
 233         if (keepalive &&
 234             setsockopt(STDIN_FILENO, SOL_SOCKET, SO_KEEPALIVE, (char *)&on,
 235             sizeof(on)) < 0)
 236                 syslog(LOG_WARNING, "setsockopt (SO_KEEPALIVE): %m");
 237         linger.l_onoff = 1;
 238         linger.l_linger = 60;                   /* XXX */
 239         if (setsockopt(STDIN_FILENO, SOL_SOCKET, SO_LINGER, (char *)&linger,
 240             sizeof (linger)) < 0)
 241                 syslog(LOG_WARNING, "setsockopt (SO_LINGER): %m");
 242         proto = getprotobyname("tcp");
 243         (void)setsockopt(STDIN_FILENO, proto->p_proto, TCP_NODELAY, &on,
 244             sizeof(on));
 245         doit((struct sockaddr *)&from, (struct sockaddr *)&local);
 246 }
 247
 248 extern char     **environ;
 249
 250 static void
 251 doit(struct sockaddr *fromp, struct sockaddr *localp)
 252 {
 253         struct passwd *pwd, pwres;
 254         in_port_t port;
 255         struct pollfd set[2];
 256         int cc, pv[2], pid, s = -1;     /* XXX gcc */
 257         int one = 1;
 258         char *hostname, *errorhost = NULL;      /* XXX gcc */
 259         const char *cp;
 260         char sig, buf[BUFSIZ];
 261         char cmdbuf[NCARGS+1], locuser[16], remuser[16];
 262         char remotehost[2 * MAXHOSTNAMELEN + 1];
 263         char hostnamebuf[2 * MAXHOSTNAMELEN + 1];
 264 #ifdef  LOGIN_CAP
 265         login_cap_t *lc;
 266 #endif
 267         char naddr[NI_MAXHOST];
 268         char saddr[NI_MAXHOST];
 269         char raddr[NI_MAXHOST];
 270         char pbuf[NI_MAXSERV];
 271         int af = fromp->sa_family;
 272         u_int16_t *portp;
 273         struct addrinfo hints, *res, *res0;
 274         int gaierror;
 275         const int niflags = NI_NUMERICHOST | NI_NUMERICSERV;
 276         const char *errormsg = NULL, *errorstr = NULL;
 277         char pwbuf[1024];
 278
 279         (void)signal(SIGINT, SIG_DFL);
 280         (void)signal(SIGQUIT, SIG_DFL);
 281         (void)signal(SIGTERM, SIG_DFL);
 282 #ifdef DEBUG
 283         {
 284                 int t = open(_PATH_TTY, O_RDWR);
 285                 if (t >= 0) {
 286                         ioctl(t, TIOCNOTTY, NULL);
 287                         (void)close(t);
 288                 }
 289         }
 290 #endif
 291         switch (af) {
 292         case AF_INET:
 293                 portp = &((struct sockaddr_in *)fromp)->sin_port;
 294                 break;
 295 #ifdef INET6
 296         case AF_INET6:
 297                 portp = &((struct sockaddr_in6 *)fromp)->sin6_port;
 298                 break;
 299 #endif
 300         default:
 301                 syslog(LOG_ERR, "malformed \"from\" address (af %d)", af);
 302                 exit(EXIT_FAILURE);
 303         }
 304         if (getnameinfo(fromp, fromp->sa_len, naddr, sizeof(naddr),
 305                         pbuf, sizeof(pbuf), niflags) != 0) {
 306                 syslog(LOG_ERR, "malformed \"from\" address (af %d)", af);
 307                 exit(EXIT_FAILURE);
 308         }
 309 #ifdef IP_OPTIONS
 310         if (af == AF_INET) {
 311
 312         u_char optbuf[BUFSIZ/3];
 313         socklen_t optsize = sizeof(optbuf);
 314         int ipproto;
 315         unsigned int i;
 316         struct protoent *ip;
 317
 318         if ((ip = getprotobyname("ip")) != NULL)
 319                 ipproto = ip->p_proto;
 320         else
 321                 ipproto = IPPROTO_IP;
 322         if (!getsockopt(0, ipproto, IP_OPTIONS, (char *)optbuf, &optsize) &&
 323             optsize != 0) {
 324                 for (i = 0; i < optsize;) {
 325                         u_char c = optbuf[i];
 326                         if (c == IPOPT_LSRR || c == IPOPT_SSRR) {
 327                                 syslog(LOG_NOTICE,
 328                                     "Connection refused from %s "
 329                                     "with IP option %s",
 330                                     inet_ntoa((
 331                                     (struct sockaddr_in *)fromp)->sin_addr),
 332                                     c == IPOPT_LSRR ? "LSRR" : "SSRR");
 333                                 exit(EXIT_FAILURE);
 334                         }
 335                         if (c == IPOPT_EOL)
 336                                 break;
 337                         i += (c == IPOPT_NOP) ? 1 : optbuf[i + 1];
 338                 }
 339         }
 340         }
 341 #endif
 342         if (ntohs(*portp) >= IPPORT_RESERVED
 343             || ntohs(*portp) < IPPORT_RESERVED / 2) {
 344                 syslog(LOG_NOTICE|LOG_AUTH,
 345                     "Connection from %s on illegal port %u",
 346                     naddr, ntohs(*portp));
 347                 exit(EXIT_FAILURE);
 348         }
 349
 350         (void) alarm(60);
 351         port = 0;
 352         for (;;) {
 353                 char c;
 354
 355                 if ((cc = read(STDIN_FILENO, &c, 1)) != 1) {
 356                         if (cc < 0)
 357                                 syslog(LOG_ERR, "read: %m");
 358                         (void)shutdown(0, SHUT_RDWR);
 359                         exit(EXIT_FAILURE);
 360                 }
 361                 if (c == 0)
 362                         break;
 363                 port = port * 10 + c - '0';
 364         }
 365
 366         (void) alarm(0);
 367         if (port != 0) {
 368                 int lport = IPPORT_RESERVED - 1;
 369                 s = rresvport_af_addr(&lport, af, localp);
 370                 if (s < 0) {
 371                         syslog(LOG_ERR, "can't get stderr port: %m");
 372                         exit(EXIT_FAILURE);
 373                 }
 374                 if (port >= IPPORT_RESERVED) {
 375                         syslog(LOG_ERR, "2nd port not reserved");
 376                         exit(EXIT_FAILURE);
 377                 }
 378                 *portp = htons(port);
 379                 if (connect(s, fromp, fromp->sa_len) < 0) {
 380                         syslog(LOG_ERR, "connect second port %d: %m", port);
 381                         exit(EXIT_FAILURE);
 382                 }
 383         }
 384
 385
 386 #ifdef notdef
 387         /* from inetd, socket is already on 0, 1, 2 */
 388         (void)dup2(f, STDIN_FILENO);
 389         (void)dup2(f, STDOUT_FILENO);
 390         (void)dup2(f, STDERR_FILENO);
 391 #endif
 392         if (getnameinfo(fromp, fromp->sa_len, saddr, sizeof(saddr),
 393                         NULL, 0, NI_NAMEREQD) == 0) {
 394                 /*
 395                  * If name returned by getnameinfo is in our domain,
 396                  * attempt to verify that we haven't been fooled by someone
 397                  * in a remote net; look up the name and check that this
 398                  * address corresponds to the name.
 399                  */
 400                 hostname = saddr;
 401                 res0 = NULL;
 402                 if (check_all || local_domain(saddr)) {
 403                         (void)strlcpy(remotehost, saddr, sizeof(remotehost));
 404                         errorhost = remotehost;
 405                         (void)memset(&hints, 0, sizeof(hints));
 406                         hints.ai_family = fromp->sa_family;
 407                         hints.ai_socktype = SOCK_STREAM;
 408                         hints.ai_flags = AI_CANONNAME;
 409                         gaierror = getaddrinfo(remotehost, pbuf, &hints, &res0);
 410                         if (gaierror) {
 411                                 syslog(LOG_NOTICE,
 412                                     "Couldn't look up address for %s: %s",
 413                                     remotehost, gai_strerror(gaierror));
 414                                 errorstr =
 415                                 "Couldn't look up address for your host (%s)\n";
 416                                 hostname = naddr;
 417                         } else {
 418                                 for (res = res0; res; res = res->ai_next) {
 419                                         if (res->ai_family != fromp->sa_family)
 420                                                 continue;
 421                                         if (res->ai_addrlen != fromp->sa_len)
 422                                                 continue;
 423                                         if (getnameinfo(res->ai_addr,
 424                                                 res->ai_addrlen,
 425                                                 raddr, sizeof(raddr), NULL, 0,
 426                                                 niflags) == 0
 427                                          && strcmp(naddr, raddr) == 0) {
 428                                                 hostname = res->ai_canonname
 429                                                         ? res->ai_canonname
 430                                                         : saddr;
 431                                                 break;
 432                                         }
 433                                 }
 434                                 if (res == NULL) {
 435                                         syslog(LOG_NOTICE,
 436                                           "Host addr %s not listed for host %s",
 437                                             naddr, res0->ai_canonname
 438                                                     ? res0->ai_canonname
 439                                                     : saddr);
 440                                         errorstr =
 441                                             "Host address mismatch for %s\n";
 442                                         hostname = naddr;
 443                                 }
 444                         }
 445                 }
 446                 (void)strlcpy(hostnamebuf, hostname, sizeof(hostnamebuf));
 447                 hostname = hostnamebuf;
 448                 if (res0)
 449                         freeaddrinfo(res0);
 450         } else {
 451                 (void)strlcpy(hostnamebuf, naddr, sizeof(hostnamebuf));
 452                 errorhost = hostname = hostnamebuf;
 453         }
 454
 455         (void)alarm(60);
 456         getstr(remuser, sizeof(remuser), "remuser");
 457         getstr(locuser, sizeof(locuser), "locuser");
 458         getstr(cmdbuf, sizeof(cmdbuf), "command");
 459         (void)alarm(0);
 460
 461 #ifdef USE_PAM
 462         pam_err = pam_start("rsh", locuser, &pamc, &pamh);
 463         if (pam_err != PAM_SUCCESS) {
 464                 syslog(LOG_ERR|LOG_AUTH, "pam_start(): %s",
 465                     pam_strerror(pamh, pam_err));
 466                 rshd_errx(EXIT_FAILURE, incorrect);
 467         }
 468
 469         if ((pam_err = pam_set_item(pamh, PAM_RUSER, remuser)) != PAM_SUCCESS ||
 470             (pam_err = pam_set_item(pamh, PAM_RHOST, hostname)) != PAM_SUCCESS){
 471                 syslog(LOG_ERR|LOG_AUTH, "pam_set_item(): %s",
 472                     pam_strerror(pamh, pam_err));
 473                 rshd_errx(EXIT_FAILURE, incorrect);
 474         }
 475
 476         pam_err = pam_authenticate(pamh, 0);
 477         if (pam_err == PAM_SUCCESS) {
 478                 if ((pam_err = pam_get_user(pamh, &cp, NULL)) == PAM_SUCCESS) {
 479                         (void)strlcpy(locuser, cp, sizeof(locuser));
 480                         /* XXX truncation! */
 481                 }
 482                 pam_err = pam_acct_mgmt(pamh, 0);
 483         }
 484         if (pam_err != PAM_SUCCESS) {
 485                 errorstr = incorrect;
 486                 errormsg = pam_strerror(pamh, pam_err);
 487                 goto badlogin;
 488         }
 489 #endif /* USE_PAM */
 490         setpwent();
 491         if (getpwnam_r(locuser, &pwres, pwbuf, sizeof(pwbuf), &pwd) != 0 ||
 492             pwd == NULL) {
 493                 syslog(LOG_INFO|LOG_AUTH,
 494                     "%s@%s as %s: unknown login. cmd='%.80s'",
 495                     remuser, hostname, locuser, cmdbuf);
 496                 if (errorstr == NULL)
 497                         errorstr = "Permission denied.";
 498                 rshd_errx(EXIT_FAILURE, errorstr, errorhost);
 499         }
 500 #ifdef LOGIN_CAP
 501         lc = login_getclass(pwd ? pwd->pw_class : NULL);
 502 #endif
 503
 504         if (chdir(pwd->pw_dir) < 0) {
 505                 if (chdir("/") < 0
 506 #ifdef LOGIN_CAP
 507                     || login_getcapbool(lc, "requirehome", pwd->pw_uid ? 1 : 0)
 508 #endif
 509                 ) {
 510                         syslog(LOG_INFO|LOG_AUTH,
 511                             "%s@%s as %s: no home directory. cmd='%.80s'",
 512                             remuser, hostname, locuser, cmdbuf);
 513                         rshd_errx(EXIT_SUCCESS, "No remote home directory.");
 514                 }
 515         }
 516
 517 #ifndef USE_PAM
 518         if (errorstr ||
 519             (pwd->pw_passwd != 0 && *pwd->pw_passwd != '\0' &&
 520                 iruserok_sa(fromp, fromp->sa_len, pwd->pw_uid == 0, remuser,
 521                         locuser) < 0)) {
 522                 errormsg = __rcmd_errstr ? __rcmd_errstr : "unknown error";
 523                 if (errorstr == NULL)
 524                         errorstr = "Permission denied.";
 525                 goto badlogin;
 526         }
 527
 528         if (pwd->pw_uid && !access(_PATH_NOLOGIN, F_OK))
 529                 rshd_errx(EXIT_FAILURE, "Logins currently disabled.");
 530 #endif
 531
 532 #ifdef LOGIN_CAP
 533         /*
 534          * PAM modules might add supplementary groups in
 535          * pam_setcred(), so initialize them first.
 536          * But we need to open the session as root.
 537          */
 538         if (setusercontext(lc, pwd, pwd->pw_uid, LOGIN_SETGROUP) != 0) {
 539                 syslog(LOG_ERR, "setusercontext: %m");
 540                 exit(EXIT_FAILURE);
 541         }
 542 #else
 543         initgroups(pwd->pw_name, pwd->pw_gid);
 544 #endif
 545
 546 #ifdef USE_PAM
 547         if ((pam_err = pam_open_session(pamh, 0)) != PAM_SUCCESS) {
 548                 syslog(LOG_ERR, "pam_open_session: %s",
 549                     pam_strerror(pamh, pam_err));
 550         } else if ((pam_err = pam_setcred(pamh, PAM_ESTABLISH_CRED))
 551             != PAM_SUCCESS) {
 552                 syslog(LOG_ERR, "pam_setcred: %s", pam_strerror(pamh, pam_err));
 553         }
 554 #endif
 555
 556         (void)write(STDERR_FILENO, "\0", 1);
 557         sent_null = 1;
 558
 559         if (port) {
 560                 if (pipe(pv) < 0)
 561                         rshd_errx(EXIT_FAILURE, "Can't make pipe. (%s)",
 562                             strerror(errno));
 563                 pid = fork();
 564                 if (pid == -1)
 565                         rshd_errx(EXIT_FAILURE, "Can't fork. (%s)",
 566                             strerror(errno));
 567                 if (pid) {
 568                         (void)close(STDIN_FILENO);
 569                         (void)close(STDOUT_FILENO);
 570                         (void)close(STDERR_FILENO);
 571                         (void)close(pv[1]);
 572
 573                         set[0].fd = s;
 574                         set[0].events = POLLIN;
 575                         set[1].fd = pv[0];
 576                         set[1].events = POLLIN;
 577                         ioctl(pv[0], FIONBIO, (char *)&one);
 578
 579                         /* should set s nbio! */
 580                         do {
 581 #if defined(__minix)
 582                                 if (set[0].events == 0 && set[1].events == 0)
 583                                         break;
 584 #endif /* defined(__minix) */
 585                                 if (poll(set, 2, INFTIM) < 0)
 586                                         break;
 587                                 if (set[0].revents & POLLIN) {
 588                                         int     ret;
 589
 590                                         ret = read(s, &sig, 1);
 591                                         if (ret <= 0)
 592                                                 set[0].events = 0;
 593                                         else
 594                                                 killpg(pid, sig);
 595                                 }
 596                                 if (set[1].revents & POLLIN) {
 597                                         errno = 0;
 598                                         cc = read(pv[0], buf, sizeof(buf));
 599                                         if (cc <= 0) {
 600                                                 shutdown(s, SHUT_RDWR);
 601                                                 set[1].events = 0;
 602                                         } else {
 603                                                 (void)write(s, buf, cc);
 604                                         }
 605                                 }
 606
 607                         } while ((set[0].revents | set[1].revents) & POLLIN);
 608                         PAM_END;
 609                         exit(EXIT_SUCCESS);
 610                 }
 611                 (void)close(s);
 612                 (void)close(pv[0]);
 613                 (void)dup2(pv[1], STDERR_FILENO);
 614                 close(pv[1]);
 615         }
 616 #ifdef USE_PAM
 617         else {
 618                 pid = fork();
 619                 if (pid == -1)
 620                         rshd_errx(EXIT_FAILURE, "Can't fork. (%s)",
 621                             strerror(errno));
 622                 if (pid) {
 623                         pid_t xpid;
 624                         int status;
 625                         if ((xpid = waitpid(pid, &status, 0)) != pid) {
 626                                 pam_err = pam_close_session(pamh, 0);
 627                                 if (pam_err != PAM_SUCCESS) {
 628                                         syslog(LOG_ERR,
 629                                             "pam_close_session: %s",
 630                                             pam_strerror(pamh, pam_err));
 631                                 }
 632                                 PAM_END;
 633                                 if (xpid != -1)
 634                                         syslog(LOG_WARNING,
 635                                             "wrong PID: %d != %d", pid, xpid);
 636                                 else
 637                                         syslog(LOG_WARNING,
 638                                             "wait pid=%d failed %m", pid);
 639                                 exit(EXIT_FAILURE);
 640                         }
 641                         exit(EXIT_SUCCESS);
 642                 }
 643         }
 644 #endif
 645
 646 #ifdef F_CLOSEM
 647         (void)fcntl(STDERR_FILENO + 1, F_CLOSEM, 0);
 648 #else
 649         for (fd = getdtablesize(); fd > STDERR_FILENO; fd--)
 650                 (void)close(fd);
 651 #endif
 652         if (setsid() == -1)
 653                 syslog(LOG_ERR, "setsid() failed: %m");
 654 #ifdef USE_PAM
 655         if (setlogin(pwd->pw_name) < 0)
 656                 syslog(LOG_ERR, "setlogin() failed: %m");
 657
 658         if (*pwd->pw_shell == '\0')
 659                 pwd->pw_shell = __UNCONST(_PATH_BSHELL);
 660
 661         (void)pam_setenv(pamh, "HOME", pwd->pw_dir, 1);
 662         (void)pam_setenv(pamh, "SHELL", pwd->pw_shell, 1);
 663         (void)pam_setenv(pamh, "USER", pwd->pw_name, 1);
 664         (void)pam_setenv(pamh, "PATH", _PATH_DEFPATH, 1);
 665         environ = pam_getenvlist(pamh);
 666         (void)pam_end(pamh, pam_err);
 667 #else
 668 #ifdef LOGIN_CAP
 669         {
 670                 char *sh;
 671                 if ((sh = login_getcapstr(lc, "shell", NULL, NULL))) {
 672                         if(!(sh = strdup(sh))) {
 673                                 syslog(LOG_ERR, "Cannot alloc mem");
 674                                 exit(EXIT_FAILURE);
 675                         }
 676                         pwd->pw_shell = sh;
 677                 }
 678         }
 679 #endif
 680 {
 681         static char *envinit[] = { NULL };
 682         environ = envinit;
 683 }
 684         setenv("PATH", _PATH_DEFPATH, 1);
 685         setenv("HOME", pwd->pw_dir, 1);
 686         setenv("SHELL", pwd->pw_shell, 1);
 687         setenv("USER", pwd->pw_name, 1);
 688 #endif
 689
 690         cp = strrchr(pwd->pw_shell, '/');
 691         if (cp)
 692                 cp++;
 693         else
 694                 cp = pwd->pw_shell;
 695
 696 #ifdef LOGIN_CAP
 697         if (setusercontext(lc, pwd, pwd->pw_uid,
 698                 LOGIN_SETALL & ~LOGIN_SETGROUP) < 0) {
 699                 syslog(LOG_ERR, "setusercontext(): %m");
 700                 exit(EXIT_FAILURE);
 701         }
 702         login_close(lc);
 703 #else
 704         (void)setgid((gid_t)pwd->pw_gid);
 705         (void)setuid((uid_t)pwd->pw_uid);
 706 #endif
 707         endpwent();
 708         if (log_success || pwd->pw_uid == 0) {
 709                 syslog(LOG_INFO|LOG_AUTH, "%s@%s as %s: cmd='%.80s'",
 710                     remuser, hostname, locuser, cmdbuf);
 711         }
 712         (void)execl(pwd->pw_shell, cp, "-c", cmdbuf, NULL);
 713         rshd_errx(EXIT_FAILURE, "%s: %s", pwd->pw_shell, strerror(errno));
 714 badlogin:
 715         syslog(LOG_INFO|LOG_AUTH,
 716             "%s@%s as %s: permission denied (%s). cmd='%.80s'",
 717             remuser, hostname, locuser, errormsg, cmdbuf);
 718         rshd_errx(EXIT_FAILURE, errorstr, errorhost);
 719 }
 720
 721 /*
 722  * Report error to client.  Note: can't be used until second socket has
 723  * connected to client, or older clients will hang waiting for that
 724  * connection first.
 725  */
 726
 727 #include <stdarg.h>
 728
 729 static void
 730 rshd_errx(int error, const char *fmt, ...)
 731 {
 732         va_list ap;
 733         int len, rv;
 734         char *bp, buf[BUFSIZ];
 735         va_start(ap, fmt);
 736         bp = buf;
 737         if (sent_null == 0) {
 738                 *bp++ = 1;
 739                 len = 1;
 740         } else
 741                 len = 0;
 742         rv = vsnprintf(bp, sizeof(buf) - 2, fmt, ap);
 743         bp[rv++] = '\n';
 744         (void)write(STDERR_FILENO, buf, len + rv);
 745         va_end(ap);
 746         exit(error);
 747 }
 748
 749 static void
 750 getstr(char *buf, int cnt, const char *err)
 751 {
 752         char c;
 753
 754         do {
 755                 if (read(STDIN_FILENO, &c, 1) != 1)
 756                         exit(EXIT_FAILURE);
 757                 *buf++ = c;
 758                 if (--cnt == 0)
 759                         rshd_errx(EXIT_FAILURE, "%s too long", err);
 760         } while (c != 0);
 761 }
 762
 763 /*
 764  * Check whether host h is in our local domain,
 765  * defined as sharing the last two components of the domain part,
 766  * or the entire domain part if the local domain has only one component.
 767  * If either name is unqualified (contains no '.'),
 768  * assume that the host is local, as it will be
 769  * interpreted as such.
 770  */
 771 static int
 772 local_domain(char *h)
 773 {
 774         char localhost[MAXHOSTNAMELEN + 1];
 775         char *p1, *p2;
 776
 777         localhost[0] = 0;
 778         (void)gethostname(localhost, sizeof(localhost));
 779         localhost[sizeof(localhost) - 1] = '\0';
 780         p1 = topdomain(localhost);
 781         p2 = topdomain(h);
 782         if (p1 == NULL || p2 == NULL || !strcasecmp(p1, p2))
 783                 return (1);
 784         return (0);
 785 }
 786
 787 static char *
 788 topdomain(char *h)
 789 {
 790         char *p, *maybe = NULL;
 791         int dots = 0;
 792
 793         for (p = h + strlen(h); p >= h; p--) {
 794                 if (*p == '.') {
 795                         if (++dots == 2)
 796                                 return (p);
 797                         maybe = p;
 798                 }
 799         }
 800         return (maybe);
 801 }
 802
 803 static void
 804 usage(void)
 805 {
 806
 807         syslog(LOG_ERR, "Usage: %s [-%s]", getprogname(), OPTIONS);
 808         exit(EXIT_FAILURE);
 809 }