appl/rsh/rshd.c

   1 /*
   2  * Copyright (c) 1997-2007 Kungliga Tekniska Högskolan
   3  * (Royal Institute of Technology, Stockholm, Sweden).
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  *
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  *
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  *
  17  * 3. Neither the name of the Institute 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 INSTITUTE 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 INSTITUTE 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
  34 #include "rsh_locl.h"
  35 #include "login_locl.h"
  36 RCSID("$Id$");
  37
  38 int
  39 login_access( struct passwd *user, char *from);
  40 int
  41 read_limits_conf(const char *file, const struct passwd *pwd);
  42
  43 #ifdef NEED_IRUSEROK_PROTO
  44 int iruserok(uint32_t, int, const char *, const char *);
  45 #endif
  46
  47 enum auth_method auth_method;
  48
  49 #ifdef KRB5
  50 krb5_context context;
  51 krb5_keyblock *keyblock;
  52 krb5_crypto crypto;
  53 #endif
  54
  55 #ifdef KRB5
  56 krb5_ccache ccache, ccache2;
  57 int kerberos_status = 0;
  58 #endif
  59
  60 int do_encrypt = 0;
  61
  62 static int do_unique_tkfile           = 0;
  63 static char tkfile[MAXPATHLEN] = "";
  64
  65 static int do_inetd = 1;
  66 static char *port_str;
  67 static int do_rhosts = 1;
  68 static int do_kerberos = 0;
  69 #define DO_KRB5 4
  70 static int do_vacuous = 0;
  71 static int do_log = 1;
  72 static int do_newpag = 1;
  73 static int do_addr_verify = 0;
  74 static int do_keepalive = 1;
  75 static int do_version;
  76 static int do_help = 0;
  77
  78 static void
  79 syslog_and_die (const char *m, ...)
  80     __attribute__ ((format (printf, 1, 2)));
  81
  82 static void
  83 syslog_and_die (const char *m, ...)
  84 {
  85     va_list args;
  86
  87     va_start(args, m);
  88     vsyslog (LOG_ERR, m, args);
  89     va_end(args);
  90     exit (1);
  91 }
  92
  93 static void
  94 fatal (int, const char*, const char *, ...)
  95     __attribute__ ((noreturn, format (printf, 3, 4)));
  96
  97 static void
  98 fatal (int sock, const char *what, const char *m, ...)
  99 {
 100     va_list args;
 101     char buf[BUFSIZ];
 102     size_t len;
 103
 104     *buf = 1;
 105     va_start(args, m);
 106     len = vsnprintf (buf + 1, sizeof(buf) - 1, m, args);
 107     len = min(len, sizeof(buf) - 1);
 108     va_end(args);
 109     if(what != NULL)
 110         syslog (LOG_ERR, "%s: %s: %s", what, strerror(errno), buf + 1);
 111     else
 112         syslog (LOG_ERR, "%s", buf + 1);
 113     net_write (sock, buf, len + 1);
 114     exit (1);
 115 }
 116
 117 static char *
 118 read_str (int s, size_t sz, char *expl)
 119 {
 120     char *str = malloc(sz);
 121     char *p = str;
 122     if(str == NULL)
 123         fatal(s, NULL, "%s too long", expl);
 124     while(p < str + sz) {
 125         if(net_read(s, p, 1) != 1)
 126             syslog_and_die("read: %s", strerror(errno));
 127         if(*p == '\0')
 128             return str;
 129         p++;
 130     }
 131     fatal(s, NULL, "%s too long", expl);
 132 }
 133
 134 static int
 135 recv_bsd_auth (int s, u_char *buf,
 136                struct sockaddr_in *thisaddr,
 137                struct sockaddr_in *thataddr,
 138                char **client_username,
 139                char **server_username,
 140                char **cmd)
 141 {
 142     struct passwd *pwd;
 143
 144     *client_username = read_str (s, USERNAME_SZ, "local username");
 145     *server_username = read_str (s, USERNAME_SZ, "remote username");
 146     *cmd = read_str (s, ARG_MAX + 1, "command");
 147     pwd = getpwnam(*server_username);
 148     if (pwd == NULL)
 149         fatal(s, NULL, "Login incorrect.");
 150     if (iruserok(thataddr->sin_addr.s_addr, pwd->pw_uid == 0,
 151                  *client_username, *server_username))
 152         fatal(s, NULL, "Login incorrect.");
 153     return 0;
 154 }
 155
 156 #ifdef KRB5
 157 static int
 158 save_krb5_creds (int s,
 159                  krb5_auth_context auth_context,
 160                  krb5_principal client)
 161
 162 {
 163     int ret;
 164     krb5_data remote_cred;
 165
 166     krb5_data_zero (&remote_cred);
 167     ret= krb5_read_message (context, (void *)&s, &remote_cred);
 168     if (ret) {
 169         krb5_data_free(&remote_cred);
 170         return 0;
 171     }
 172     if (remote_cred.length == 0)
 173         return 0;
 174
 175     ret = krb5_cc_new_unique(context, krb5_cc_type_memory, NULL, &ccache);
 176     if (ret) {
 177         krb5_data_free(&remote_cred);
 178         return 0;
 179     }
 180
 181     krb5_cc_initialize(context,ccache,client);
 182     ret = krb5_rd_cred2(context, auth_context, ccache, &remote_cred);
 183     if(ret != 0)
 184         syslog(LOG_INFO|LOG_AUTH,
 185                "reading creds: %s", krb5_get_err_text(context, ret));
 186     krb5_data_free (&remote_cred);
 187     if (ret)
 188         return 0;
 189     return 1;
 190 }
 191
 192 static void
 193 krb5_start_session (void)
 194 {
 195     krb5_error_code ret;
 196     char *estr;
 197
 198     ret = krb5_cc_resolve (context, tkfile, &ccache2);
 199     if (ret) {
 200         estr = krb5_get_error_string(context);
 201         syslog(LOG_WARNING, "resolve cred cache %s: %s",
 202                tkfile,
 203                estr ? estr : krb5_get_err_text(context, ret));
 204         free(estr);
 205         krb5_cc_destroy(context, ccache);
 206         return;
 207     }
 208
 209     ret = krb5_cc_copy_cache (context, ccache, ccache2);
 210     if (ret) {
 211         estr = krb5_get_error_string(context);
 212         syslog(LOG_WARNING, "storing credentials: %s",
 213                estr ? estr : krb5_get_err_text(context, ret));
 214         free(estr);
 215         krb5_cc_destroy(context, ccache);
 216         return ;
 217     }
 218
 219     krb5_cc_close(context, ccache2);
 220     krb5_cc_destroy(context, ccache);
 221     return;
 222 }
 223
 224 static int protocol_version;
 225
 226 static krb5_boolean
 227 match_kcmd_version(const void *data, const char *version)
 228 {
 229     if(strcmp(version, KCMD_NEW_VERSION) == 0) {
 230         protocol_version = 2;
 231         return TRUE;
 232     }
 233     if(strcmp(version, KCMD_OLD_VERSION) == 0) {
 234         protocol_version = 1;
 235         key_usage = KRB5_KU_OTHER_ENCRYPTED;
 236         return TRUE;
 237     }
 238     return FALSE;
 239 }
 240
 241
 242 static int
 243 recv_krb5_auth (int s, u_char *buf,
 244                 struct sockaddr *thisaddr,
 245                 struct sockaddr *thataddr,
 246                 char **client_username,
 247                 char **server_username,
 248                 char **cmd)
 249 {
 250     uint32_t len;
 251     krb5_auth_context auth_context = NULL;
 252     krb5_ticket *ticket;
 253     krb5_error_code status;
 254     krb5_data cksum_data;
 255     krb5_principal server;
 256     char *str;
 257
 258     if (memcmp (buf, "\x00\x00\x00\x13", 4) != 0)
 259         return -1;
 260     len = (buf[0] << 24) | (buf[1] << 16) | (buf[2] << 8) | (buf[3]);
 261
 262     if (net_read(s, buf, len) != len)
 263         syslog_and_die ("reading auth info: %s", strerror(errno));
 264     if (len != sizeof(KRB5_SENDAUTH_VERSION)
 265         || memcmp (buf, KRB5_SENDAUTH_VERSION, len) != 0)
 266         syslog_and_die ("bad sendauth version: %.8s", buf);
 267
 268     status = krb5_sock_to_principal (context,
 269                                      s,
 270                                      "host",
 271                                      KRB5_NT_SRV_HST,
 272                                      &server);
 273     if (status)
 274         syslog_and_die ("krb5_sock_to_principal: %s",
 275                         krb5_get_err_text(context, status));
 276
 277     status = krb5_recvauth_match_version(context,
 278                                          &auth_context,
 279                                          &s,
 280                                          match_kcmd_version,
 281                                          NULL,
 282                                          server,
 283                                          KRB5_RECVAUTH_IGNORE_VERSION,
 284                                          NULL,
 285                                          &ticket);
 286     krb5_free_principal (context, server);
 287     if (status)
 288         syslog_and_die ("krb5_recvauth: %s",
 289                         krb5_get_err_text(context, status));
 290
 291     *server_username = read_str (s, USERNAME_SZ, "remote username");
 292     *cmd = read_str (s, ARG_MAX + 1, "command");
 293     *client_username = read_str (s, ARG_MAX + 1, "local username");
 294
 295     if(protocol_version == 2) {
 296         status = krb5_auth_con_getremotesubkey(context, auth_context,
 297                                                &keyblock);
 298         if(status != 0 || keyblock == NULL)
 299             syslog_and_die("failed to get remote subkey");
 300     } else if(protocol_version == 1) {
 301         status = krb5_auth_con_getkey (context, auth_context, &keyblock);
 302         if(status != 0 || keyblock == NULL)
 303             syslog_and_die("failed to get key");
 304     }
 305     if (status != 0 || keyblock == NULL)
 306        syslog_and_die ("krb5_auth_con_getkey: %s",
 307                        krb5_get_err_text(context, status));
 308
 309     status = krb5_crypto_init(context, keyblock, 0, &crypto);
 310     if(status)
 311         syslog_and_die("krb5_crypto_init: %s",
 312                        krb5_get_err_text(context, status));
 313
 314
 315     cksum_data.length = asprintf (&str,
 316                                   "%u:%s%s",
 317                                   ntohs(socket_get_port (thisaddr)),
 318                                   *cmd,
 319                                   *server_username);
 320     if (str == NULL)
 321         syslog_and_die ("asprintf: out of memory");
 322     cksum_data.data = str;
 323
 324     status = krb5_verify_authenticator_checksum(context,
 325                                                 auth_context,
 326                                                 cksum_data.data,
 327                                                 cksum_data.length);
 328
 329     if (status)
 330         syslog_and_die ("krb5_verify_authenticator_checksum: %s",
 331                         krb5_get_err_text(context, status));
 332
 333     free (cksum_data.data);
 334
 335     if (strncmp (*client_username, "-u ", 3) == 0) {
 336         do_unique_tkfile = 1;
 337         memmove (*client_username, *client_username + 3,
 338                  strlen(*client_username) - 2);
 339     }
 340
 341     if (strncmp (*client_username, "-U ", 3) == 0) {
 342         char *end, *temp_tkfile;
 343
 344         do_unique_tkfile = 1;
 345         if (strncmp (*client_username + 3, "FILE:", 5) == 0) {
 346             temp_tkfile = tkfile;
 347         } else {
 348             strlcpy (tkfile, "FILE:", sizeof(tkfile));
 349             temp_tkfile = tkfile + 5;
 350         }
 351         end = strchr(*client_username + 3,' ');
 352         if (end == NULL)
 353             syslog_and_die("missing argument after -U");
 354         snprintf(temp_tkfile, sizeof(tkfile) - (temp_tkfile - tkfile),
 355                  "%.*s",
 356                  (int)(end - *client_username - 3),
 357                  *client_username + 3);
 358         memmove (*client_username, end + 1, strlen(end+1)+1);
 359     }
 360
 361     kerberos_status = save_krb5_creds (s, auth_context, ticket->client);
 362
 363     if(!krb5_kuserok (context,
 364                       ticket->client,
 365                       *server_username))
 366         fatal (s, NULL, "Permission denied.");
 367
 368     if (strncmp (*cmd, "-x ", 3) == 0) {
 369         do_encrypt = 1;
 370         memmove (*cmd, *cmd + 3, strlen(*cmd) - 2);
 371     } else {
 372         if(do_encrypt)
 373             fatal (s, NULL, "Encryption is required.");
 374         do_encrypt = 0;
 375     }
 376
 377     {
 378         char *name;
 379
 380         if (krb5_unparse_name (context, ticket->client, &name) == 0) {
 381             char addr_str[256];
 382
 383             if (inet_ntop (thataddr->sa_family,
 384                            socket_get_address (thataddr),
 385                            addr_str, sizeof(addr_str)) == NULL)
 386                 strlcpy (addr_str, "unknown address",
 387                                  sizeof(addr_str));
 388
 389             syslog(LOG_INFO|LOG_AUTH,
 390                    "kerberos v5 shell from %s on %s as %s, cmd '%.80s'",
 391                    name,
 392                    addr_str,
 393                    *server_username,
 394                    *cmd);
 395             free (name);
 396         }
 397     }
 398
 399     krb5_auth_con_free(context, auth_context);
 400
 401     return 0;
 402 }
 403 #endif /* KRB5 */
 404
 405 static void
 406 rshd_loop (int from0, int to0,
 407            int to1,   int from1,
 408            int to2,   int from2,
 409            int have_errsock)
 410 {
 411     fd_set real_readset;
 412     int max_fd;
 413     int count = 2;
 414     char *buf;
 415
 416     if(from0 >= FD_SETSIZE || from1 >= FD_SETSIZE || from2 >= FD_SETSIZE)
 417         errx (1, "fd too large");
 418
 419 #ifdef KRB5
 420     if(auth_method == AUTH_KRB5 && protocol_version == 2)
 421         init_ivecs(0, have_errsock);
 422 #endif
 423
 424     FD_ZERO(&real_readset);
 425     FD_SET(from0, &real_readset);
 426     FD_SET(from1, &real_readset);
 427     FD_SET(from2, &real_readset);
 428     max_fd = max(from0, max(from1, from2)) + 1;
 429
 430     buf = malloc(max(RSHD_BUFSIZ, RSH_BUFSIZ));
 431     if (buf == NULL)
 432         syslog_and_die("out of memory");
 433
 434     for (;;) {
 435         int ret;
 436         fd_set readset = real_readset;
 437
 438         ret = select (max_fd, &readset, NULL, NULL, NULL);
 439         if (ret < 0) {
 440             if (errno == EINTR)
 441                 continue;
 442             else
 443                 syslog_and_die ("select: %s", strerror(errno));
 444         }
 445         if (FD_ISSET(from0, &readset)) {
 446             ret = do_read (from0, buf, RSHD_BUFSIZ, ivec_in[0]);
 447             if (ret < 0)
 448                 syslog_and_die ("read: %s", strerror(errno));
 449             else if (ret == 0) {
 450                 close (from0);
 451                 close (to0);
 452                 FD_CLR(from0, &real_readset);
 453             } else
 454                 net_write (to0, buf, ret);
 455         }
 456         if (FD_ISSET(from1, &readset)) {
 457             ret = read (from1, buf, RSH_BUFSIZ);
 458             if (ret < 0)
 459                 syslog_and_die ("read: %s", strerror(errno));
 460             else if (ret == 0) {
 461                 close (from1);
 462                 close (to1);
 463                 FD_CLR(from1, &real_readset);
 464                 if (--count == 0)
 465                     exit (0);
 466             } else
 467                 do_write (to1, buf, ret, ivec_out[0]);
 468         }
 469         if (FD_ISSET(from2, &readset)) {
 470             ret = read (from2, buf, RSH_BUFSIZ);
 471             if (ret < 0)
 472                 syslog_and_die ("read: %s", strerror(errno));
 473             else if (ret == 0) {
 474                 close (from2);
 475                 close (to2);
 476                 FD_CLR(from2, &real_readset);
 477                 if (--count == 0)
 478                     exit (0);
 479             } else
 480                 do_write (to2, buf, ret, ivec_out[1]);
 481         }
 482    }
 483 }
 484
 485 /*
 486  * Used by `setup_copier' to create some pipe-like means of
 487  * communcation.  Real pipes would probably be the best thing, but
 488  * then the shell doesn't understand it's talking to rshd.  If
 489  * socketpair doesn't work everywhere, some autoconf magic would have
 490  * to be added here.
 491  *
 492  * If it fails creating the `pipe', it aborts by calling fatal.
 493  */
 494
 495 static void
 496 pipe_a_like (int fd[2])
 497 {
 498     if (socketpair (AF_UNIX, SOCK_STREAM, 0, fd) < 0)
 499         fatal (STDOUT_FILENO, "socketpair", "Pipe creation failed.");
 500 }
 501
 502 /*
 503  * Start a child process and leave the parent copying data to and from it.  */
 504
 505 static void
 506 setup_copier (int have_errsock)
 507 {
 508     int p0[2], p1[2], p2[2];
 509     pid_t pid;
 510
 511     pipe_a_like(p0);
 512     pipe_a_like(p1);
 513     pipe_a_like(p2);
 514     pid = fork ();
 515     if (pid < 0)
 516         fatal (STDOUT_FILENO, "fork", "Could not create child process.");
 517     if (pid == 0) { /* child */
 518         close (p0[1]);
 519         close (p1[0]);
 520         close (p2[0]);
 521         dup2 (p0[0], STDIN_FILENO);
 522         dup2 (p1[1], STDOUT_FILENO);
 523         dup2 (p2[1], STDERR_FILENO);
 524         close (p0[0]);
 525         close (p1[1]);
 526         close (p2[1]);
 527     } else { /* parent */
 528         close (p0[0]);
 529         close (p1[1]);
 530         close (p2[1]);
 531
 532         if (net_write (STDOUT_FILENO, "", 1) != 1)
 533             fatal (STDOUT_FILENO, "net_write", "Write failure.");
 534
 535         rshd_loop (STDIN_FILENO, p0[1],
 536               STDOUT_FILENO, p1[0],
 537               STDERR_FILENO, p2[0],
 538               have_errsock);
 539     }
 540 }
 541
 542 /*
 543  * Is `port' a ``reserverd'' port?
 544  */
 545
 546 static int
 547 is_reserved(u_short port)
 548 {
 549     return ntohs(port) < IPPORT_RESERVED;
 550 }
 551
 552 /*
 553  * Set the necessary part of the environment in `env'.
 554  */
 555
 556 static void
 557 setup_environment (char ***env, const struct passwd *pwd)
 558 {
 559     int i, j, path;
 560     char **e;
 561
 562     i = 0;
 563     path = 0;
 564     *env = NULL;
 565
 566     i = read_environment(_PATH_ETC_ENVIRONMENT, env);
 567     e = *env;
 568     for (j = 0; j < i; j++) {
 569         if (!strncmp(e[j], "PATH=", 5)) {
 570             path = 1;
 571         }
 572     }
 573
 574     e = *env;
 575     e = realloc(e, (i + 7) * sizeof(char *));
 576
 577     if (asprintf (&e[i++], "USER=%s",  pwd->pw_name) == -1)
 578         syslog_and_die ("asprintf: out of memory");
 579     if (asprintf (&e[i++], "HOME=%s",  pwd->pw_dir) == -1)
 580         syslog_and_die ("asprintf: out of memory");
 581     if (asprintf (&e[i++], "SHELL=%s", pwd->pw_shell) == -1)
 582         syslog_and_die ("asprintf: out of memory");
 583     if (! path) {
 584         if (asprintf (&e[i++], "PATH=%s",  _PATH_DEFPATH) == -1)
 585             syslog_and_die ("asprintf: out of memory");
 586     }
 587     asprintf (&e[i++], "SSH_CLIENT=only_to_make_bash_happy");
 588     if (do_unique_tkfile)
 589         if (asprintf (&e[i++], "KRB5CCNAME=%s", tkfile) == -1)
 590             syslog_and_die ("asprintf: out of memory");
 591     e[i++] = NULL;
 592     *env = e;
 593 }
 594
 595 static void
 596 doit (void)
 597 {
 598     u_char buf[BUFSIZ];
 599     u_char *p;
 600     struct sockaddr_storage thisaddr_ss;
 601     struct sockaddr *thisaddr = (struct sockaddr *)&thisaddr_ss;
 602     struct sockaddr_storage thataddr_ss;
 603     struct sockaddr *thataddr = (struct sockaddr *)&thataddr_ss;
 604     struct sockaddr_storage erraddr_ss;
 605     struct sockaddr *erraddr = (struct sockaddr *)&erraddr_ss;
 606     socklen_t thisaddr_len, thataddr_len;
 607     int port;
 608     int errsock = -1;
 609     char *client_user = NULL, *server_user = NULL, *cmd = NULL;
 610     struct passwd *pwd;
 611     int s = STDIN_FILENO;
 612     char **env;
 613     int ret;
 614     char that_host[NI_MAXHOST];
 615
 616     thisaddr_len = sizeof(thisaddr_ss);
 617     if (getsockname (s, thisaddr, &thisaddr_len) < 0)
 618         syslog_and_die("getsockname: %s", strerror(errno));
 619     thataddr_len = sizeof(thataddr_ss);
 620     if (getpeername (s, thataddr, &thataddr_len) < 0)
 621         syslog_and_die ("getpeername: %s", strerror(errno));
 622
 623     /* check for V4MAPPED addresses? */
 624
 625     if (do_kerberos == 0 && !is_reserved(socket_get_port(thataddr)))
 626         fatal(s, NULL, "Permission denied.");
 627
 628     p = buf;
 629     port = 0;
 630     for(;;) {
 631         if (net_read (s, p, 1) != 1)
 632             syslog_and_die ("reading port number: %s", strerror(errno));
 633         if (*p == '\0')
 634             break;
 635         else if (isdigit(*p))
 636             port = port * 10 + *p - '0';
 637         else
 638             syslog_and_die ("non-digit in port number: %c", *p);
 639     }
 640
 641     if (do_kerberos  == 0 && !is_reserved(htons(port)))
 642         fatal(s, NULL, "Permission denied.");
 643
 644     if (port) {
 645         int priv_port = IPPORT_RESERVED - 1;
 646
 647         /*
 648          * There's no reason to require a ``privileged'' port number
 649          * here, but for some reason the brain dead rsh clients
 650          * do... :-(
 651          */
 652
 653         erraddr->sa_family = thataddr->sa_family;
 654         socket_set_address_and_port (erraddr,
 655                                      socket_get_address (thataddr),
 656                                      htons(port));
 657
 658         /*
 659          * we only do reserved port for IPv4
 660          */
 661
 662         if (erraddr->sa_family == AF_INET)
 663             errsock = rresvport (&priv_port);
 664         else
 665             errsock = socket (erraddr->sa_family, SOCK_STREAM, 0);
 666         if (errsock < 0)
 667             syslog_and_die ("socket: %s", strerror(errno));
 668         if (connect (errsock,
 669                      erraddr,
 670                      socket_sockaddr_size (erraddr)) < 0) {
 671             syslog (LOG_WARNING, "connect: %s", strerror(errno));
 672             close (errsock);
 673         }
 674     }
 675
 676     if(do_kerberos) {
 677         if (net_read (s, buf, 4) != 4)
 678             syslog_and_die ("reading auth info: %s", strerror(errno));
 679
 680 #ifdef KRB5
 681             if((do_kerberos & DO_KRB5) &&
 682                recv_krb5_auth (s, buf, thisaddr, thataddr,
 683                                &client_user,
 684                                &server_user,
 685                                &cmd) == 0)
 686                 auth_method = AUTH_KRB5;
 687             else
 688 #endif /* KRB5 */
 689                 syslog_and_die ("unrecognized auth protocol: %x %x %x %x",
 690                                 buf[0], buf[1], buf[2], buf[3]);
 691     } else {
 692         if(recv_bsd_auth (s, buf,
 693                           (struct sockaddr_in *)thisaddr,
 694                           (struct sockaddr_in *)thataddr,
 695                           &client_user,
 696                           &server_user,
 697                           &cmd) == 0) {
 698             auth_method = AUTH_BROKEN;
 699             if(do_vacuous) {
 700                 printf("Remote host requires Kerberos authentication\n");
 701                 exit(0);
 702             }
 703         } else
 704             syslog_and_die("recv_bsd_auth failed");
 705     }
 706
 707     if (client_user == NULL || server_user == NULL || cmd == NULL)
 708         syslog_and_die("mising client/server/cmd");
 709
 710     pwd = getpwnam (server_user);
 711     if (pwd == NULL)
 712         fatal (s, NULL, "Login incorrect.");
 713
 714     if (*pwd->pw_shell == '\0')
 715         pwd->pw_shell = _PATH_BSHELL;
 716
 717     if (pwd->pw_uid != 0 && access (_PATH_NOLOGIN, F_OK) == 0)
 718         fatal (s, NULL, "Login disabled.");
 719
 720
 721     ret = getnameinfo_verified (thataddr, thataddr_len,
 722                                 that_host, sizeof(that_host),
 723                                 NULL, 0, 0);
 724     if (ret)
 725         fatal (s, NULL, "getnameinfo: %s", gai_strerror(ret));
 726
 727     if (login_access(pwd, that_host) == 0) {
 728         syslog(LOG_NOTICE, "Kerberos rsh denied to %s from %s",
 729                server_user, that_host);
 730         fatal(s, NULL, "Permission denied.");
 731     }
 732
 733 #ifdef HAVE_GETSPNAM
 734     {
 735         struct spwd *sp;
 736         long    today;
 737
 738         sp = getspnam(server_user);
 739         if (sp != NULL) {
 740             today = time(0)/(24L * 60 * 60);
 741             if (sp->sp_expire > 0)
 742                 if (today > sp->sp_expire)
 743                     fatal(s, NULL, "Account has expired.");
 744         }
 745     }
 746 #endif
 747
 748
 749 #ifdef HAVE_SETLOGIN
 750     if (setlogin(pwd->pw_name) < 0)
 751         syslog(LOG_ERR, "setlogin() failed: %s", strerror(errno));
 752 #endif
 753
 754 #ifdef HAVE_SETPCRED
 755     if (setpcred (pwd->pw_name, NULL) == -1)
 756         syslog(LOG_ERR, "setpcred() failure: %s", strerror(errno));
 757 #endif /* HAVE_SETPCRED */
 758
 759     /* Apply limits if not root */
 760     if(pwd->pw_uid != 0) {
 761          const char *file = _PATH_LIMITS_CONF;
 762          read_limits_conf(file, pwd);
 763     }
 764
 765     if (initgroups (pwd->pw_name, pwd->pw_gid) < 0)
 766         fatal (s, "initgroups", "Login incorrect.");
 767
 768     if (setgid(pwd->pw_gid) < 0)
 769         fatal (s, "setgid", "Login incorrect.");
 770
 771     if (setuid (pwd->pw_uid) < 0)
 772         fatal (s, "setuid", "Login incorrect.");
 773
 774     if (chdir (pwd->pw_dir) < 0)
 775         fatal (s, "chdir", "Remote directory.");
 776
 777     if (errsock >= 0) {
 778         if (dup2 (errsock, STDERR_FILENO) < 0)
 779             fatal (s, "dup2", "Cannot dup stderr.");
 780         close (errsock);
 781     } else {
 782         if (dup2 (STDOUT_FILENO, STDERR_FILENO) < 0)
 783             fatal (s, "dup2", "Cannot dup stderr.");
 784     }
 785
 786 #ifdef KRB5
 787     {
 788         int fd;
 789
 790         if (!do_unique_tkfile)
 791             snprintf(tkfile,sizeof(tkfile),"FILE:/tmp/krb5cc_%lu",
 792                      (unsigned long)pwd->pw_uid);
 793         else if (*tkfile=='\0') {
 794             snprintf(tkfile,sizeof(tkfile),"FILE:/tmp/krb5cc_XXXXXX");
 795             fd = mkstemp(tkfile+5);
 796             close(fd);
 797             unlink(tkfile+5);
 798         }
 799
 800         if (kerberos_status)
 801             krb5_start_session();
 802     }
 803 #endif
 804
 805     setup_environment (&env, pwd);
 806
 807     if (do_encrypt) {
 808         setup_copier (errsock >= 0);
 809     } else {
 810         if (net_write (s, "", 1) != 1)
 811             fatal (s, "net_write", "write failed");
 812     }
 813
 814 #if defined(KRB5)
 815     if(k_hasafs()) {
 816         char cell[64];
 817
 818         if(do_newpag)
 819             k_setpag();
 820
 821         /* XXX */
 822        if (kerberos_status) {
 823            krb5_ccache ccache;
 824            krb5_error_code status;
 825
 826            status = krb5_cc_resolve (context, tkfile, &ccache);
 827            if (!status) {
 828                if (k_afs_cell_of_file (pwd->pw_dir, cell, sizeof(cell)) == 0)
 829                    krb5_afslog_uid_home(context, ccache, cell, NULL,
 830                                         pwd->pw_uid, pwd->pw_dir);
 831                krb5_afslog_uid_home(context, ccache, NULL, NULL,
 832                                     pwd->pw_uid, pwd->pw_dir);
 833                krb5_cc_close (context, ccache);
 834            }
 835        }
 836     }
 837 #endif /* KRB5 */
 838     execle (pwd->pw_shell, pwd->pw_shell, "-c", cmd, NULL, env);
 839     err(1, "exec %s", pwd->pw_shell);
 840 }
 841
 842 struct getargs args[] = {
 843     { NULL,             'a',    arg_flag,       &do_addr_verify },
 844     { "keepalive",      'n',    arg_negative_flag,      &do_keepalive },
 845     { "inetd",          'i',    arg_negative_flag,      &do_inetd,
 846       "Not started from inetd" },
 847 #if defined(KRB5)
 848     { "kerberos",       'k',    arg_flag,       &do_kerberos,
 849       "Implement kerberised services" },
 850     { "encrypt",        'x',    arg_flag,               &do_encrypt,
 851       "Implement encrypted service" },
 852 #endif
 853     { "rhosts",         'l',    arg_negative_flag, &do_rhosts,
 854       "Don't check users .rhosts" },
 855     { "port",           'p',    arg_string,     &port_str,      "Use this port",
 856       "port" },
 857     { "vacuous",        'v',    arg_flag, &do_vacuous,
 858       "Don't accept non-kerberised connections" },
 859 #if defined(KRB5)
 860     { NULL,             'P',    arg_negative_flag, &do_newpag,
 861       "Don't put process in new PAG" },
 862 #endif
 863     /* compatibility flag: */
 864     { NULL,             'L',    arg_flag, &do_log },
 865     { "version",        0,      arg_flag,               &do_version },
 866     { "help",           0,      arg_flag,               &do_help }
 867 };
 868
 869 static void
 870 usage (int ret)
 871 {
 872     if(isatty(STDIN_FILENO))
 873         arg_printusage (args,
 874                         sizeof(args) / sizeof(args[0]),
 875                         NULL,
 876                         "");
 877     else
 878         syslog (LOG_ERR, "Usage: %s [-ikxlvPL] [-p port]", getprogname());
 879     exit (ret);
 880 }
 881
 882
 883 int
 884 main(int argc, char **argv)
 885 {
 886     int optind = 0;
 887     int on = 1;
 888
 889     setprogname (argv[0]);
 890     roken_openlog ("rshd", LOG_ODELAY | LOG_PID, LOG_AUTH);
 891
 892     if (getarg(args, sizeof(args) / sizeof(args[0]), argc, argv,
 893                &optind))
 894         usage(1);
 895
 896     if(do_help)
 897         usage (0);
 898
 899     if (do_version) {
 900         print_version(NULL);
 901         exit(0);
 902     }
 903
 904 #if defined(KRB5)
 905     if (do_encrypt)
 906         do_kerberos = 1;
 907
 908     if(do_kerberos)
 909         do_kerberos = DO_KRB5;
 910 #endif
 911
 912 #ifdef KRB5
 913     if((do_kerberos & DO_KRB5) && krb5_init_context (&context) != 0)
 914         do_kerberos &= ~DO_KRB5;
 915 #endif
 916
 917     if (!do_inetd) {
 918         int error;
 919         struct addrinfo *ai = NULL, hints;
 920         char portstr[NI_MAXSERV];
 921
 922         memset (&hints, 0, sizeof(hints));
 923         hints.ai_flags    = AI_PASSIVE;
 924         hints.ai_socktype = SOCK_STREAM;
 925         hints.ai_family   = PF_UNSPEC;
 926
 927         if(port_str != NULL) {
 928             error = getaddrinfo (NULL, port_str, &hints, &ai);
 929             if (error)
 930                 errx (1, "getaddrinfo: %s", gai_strerror (error));
 931         }
 932         if (ai == NULL) {
 933 #if defined(KRB5)
 934             if (do_kerberos) {
 935                 if (do_encrypt) {
 936                     error = getaddrinfo(NULL, "ekshell", &hints, &ai);
 937                     if(error == EAI_NONAME) {
 938                         snprintf(portstr, sizeof(portstr), "%d", 545);
 939                         error = getaddrinfo(NULL, portstr, &hints, &ai);
 940                     }
 941                     if(error)
 942                         errx (1, "getaddrinfo: %s", gai_strerror (error));
 943                 } else {
 944                     error = getaddrinfo(NULL, "kshell", &hints, &ai);
 945                     if(error == EAI_NONAME) {
 946                         snprintf(portstr, sizeof(portstr), "%d", 544);
 947                         error = getaddrinfo(NULL, portstr, &hints, &ai);
 948                     }
 949                     if(error)
 950                         errx (1, "getaddrinfo: %s", gai_strerror (error));
 951                 }
 952             } else
 953 #endif
 954                 {
 955                     error = getaddrinfo(NULL, "shell", &hints, &ai);
 956                     if(error == EAI_NONAME) {
 957                         snprintf(portstr, sizeof(portstr), "%d", 514);
 958                         error = getaddrinfo(NULL, portstr, &hints, &ai);
 959                     }
 960                     if(error)
 961                         errx (1, "getaddrinfo: %s", gai_strerror (error));
 962                 }
 963         }
 964         mini_inetd_addrinfo (ai);
 965         freeaddrinfo(ai);
 966     }
 967
 968     if (do_keepalive &&
 969         setsockopt(0, SOL_SOCKET, SO_KEEPALIVE, (char *)&on,
 970                    sizeof(on)) < 0)
 971         syslog(LOG_WARNING, "setsockopt (SO_KEEPALIVE): %s", strerror(errno));
 972
 973     /* set SO_LINGER? */
 974
 975     signal (SIGPIPE, SIG_IGN);
 976
 977     doit ();
 978     return 0;
 979 }