clientserver.c

   1 /*
   2  * The socket based protocol for setting up a connection with rsyncd.
   3  *
   4  * Copyright (C) 1998-2001 Andrew Tridgell <tridge@samba.org>
   5  * Copyright (C) 2001-2002 Martin Pool <mbp@samba.org>
   6  * Copyright (C) 2002-2007 Wayne Davison
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 3 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License along
  19  * with this program; if not, visit the http://fsf.org website.
  20  */
  21
  22 #include "rsync.h"
  23 #include "ifuncs.h"
  24
  25 extern int verbose;
  26 extern int dry_run;
  27 extern int output_motd;
  28 extern int list_only;
  29 extern int am_sender;
  30 extern int am_server;
  31 extern int am_daemon;
  32 extern int am_root;
  33 extern int rsync_port;
  34 extern int ignore_errors;
  35 extern int kluge_around_eof;
  36 extern int daemon_over_rsh;
  37 extern int sanitize_paths;
  38 extern int filesfrom_fd;
  39 extern int remote_protocol;
  40 extern int protocol_version;
  41 extern int io_timeout;
  42 extern int no_detach;
  43 extern int write_batch;
  44 extern int default_af_hint;
  45 extern int logfile_format_has_i;
  46 extern int logfile_format_has_o_or_i;
  47 extern mode_t orig_umask;
  48 extern char *bind_address;
  49 extern char *sockopts;
  50 extern char *config_file;
  51 extern char *logfile_format;
  52 extern char *files_from;
  53 extern char *tmpdir;
  54 extern struct chmod_mode_struct *chmod_modes;
  55 extern struct filter_list_struct server_filter_list;
  56 extern char curr_dir[];
  57
  58 char *auth_user;
  59 int read_only = 0;
  60 int module_id = -1;
  61 int munge_symlinks = 0;
  62 struct chmod_mode_struct *daemon_chmod_modes;
  63
  64 /* module_dirlen is the length of the module_dir string when in daemon
  65  * mode, not chrooted, and the path is not "/"; otherwise 0. */
  66 char *module_dir = NULL;
  67 unsigned int module_dirlen = 0;
  68
  69 static int rl_nulls = 0;
  70
  71 #ifdef HAVE_SIGACTION
  72 static struct sigaction sigact;
  73 #endif
  74
  75 /**
  76  * Run a client connected to an rsyncd.  The alternative to this
  77  * function for remote-shell connections is do_cmd().
  78  *
  79  * After negotiating which module to use and reading the server's
  80  * motd, this hands over to client_run().  Telling the server the
  81  * module will cause it to chroot/setuid/etc.
  82  *
  83  * Instead of doing a transfer, the client may at this stage instead
  84  * get a listing of remote modules and exit.
  85  *
  86  * @return -1 for error in startup, or the result of client_run().
  87  * Either way, it eventually gets passed to exit_cleanup().
  88  **/
  89 int start_socket_client(char *host, int remote_argc, char *remote_argv[],
  90                         int argc, char *argv[])
  91 {
  92         int fd, ret;
  93         char *p, *user = NULL;
  94
  95         /* This is redundant with code in start_inband_exchange(), but this
  96          * short-circuits a problem in the client before we open a socket,
  97          * and the extra check won't hurt. */
  98         if (**remote_argv == '/') {
  99                 rprintf(FERROR,
 100                         "ERROR: The remote path must start with a module name not a /\n");
 101                 return -1;
 102         }
 103
 104         if ((p = strrchr(host, '@')) != NULL) {
 105                 user = host;
 106                 host = p+1;
 107                 *p = '\0';
 108         }
 109
 110         fd = open_socket_out_wrapped(host, rsync_port, bind_address,
 111                                      default_af_hint);
 112         if (fd == -1)
 113                 exit_cleanup(RERR_SOCKETIO);
 114
 115         set_socket_options(fd, sockopts);
 116
 117         ret = start_inband_exchange(fd, fd, user, remote_argc, remote_argv);
 118
 119         return ret ? ret : client_run(fd, fd, -1, argc, argv);
 120 }
 121
 122 static int exchange_protocols(int f_in, int f_out, char *buf, size_t bufsiz, int am_client)
 123 {
 124         int remote_sub = -1;
 125 #if SUBPROTOCOL_VERSION != 0
 126         int our_sub = protocol_version < PROTOCOL_VERSION ? 0 : SUBPROTOCOL_VERSION;
 127 #else
 128         int our_sub = 0;
 129 #endif
 130         char *motd;
 131
 132         io_printf(f_out, "@RSYNCD: %d.%d\n", protocol_version, our_sub);
 133
 134         if (!am_client) {
 135                 motd = lp_motd_file();
 136                 if (motd && *motd) {
 137                         FILE *f = fopen(motd,"r");
 138                         while (f && !feof(f)) {
 139                                 int len = fread(buf, 1, bufsiz - 1, f);
 140                                 if (len > 0)
 141                                         write_buf(f_out, buf, len);
 142                         }
 143                         if (f)
 144                                 fclose(f);
 145                         write_sbuf(f_out, "\n");
 146                 }
 147         }
 148
 149         /* This strips the \n. */
 150         if (!read_line_old(f_in, buf, bufsiz)) {
 151                 if (am_client)
 152                         rprintf(FERROR, "rsync: did not see server greeting\n");
 153                 return -1;
 154         }
 155
 156         if (sscanf(buf, "@RSYNCD: %d.%d", &remote_protocol, &remote_sub) < 1) {
 157                 if (am_client)
 158                         rprintf(FERROR, "rsync: server sent \"%s\" rather than greeting\n", buf);
 159                 else
 160                         io_printf(f_out, "@ERROR: protocol startup error\n");
 161                 return -1;
 162         }
 163
 164         if (remote_sub < 0) {
 165                 if (remote_protocol == 30) {
 166                         if (am_client)
 167                                 rprintf(FERROR, "rsync: server is speaking an incompatible beta of protocol 30\n");
 168                         else
 169                                 io_printf(f_out, "@ERROR: your client is speaking an incompatible beta of protocol 30\n");
 170                         return -1;
 171                 }
 172                 remote_sub = 0;
 173         }
 174
 175         if (protocol_version > remote_protocol) {
 176                 protocol_version = remote_protocol;
 177                 if (remote_sub)
 178                         protocol_version--;
 179         } else if (protocol_version == remote_protocol) {
 180                 if (remote_sub != our_sub)
 181                         protocol_version--;
 182         }
 183 #if SUBPROTOCOL_VERSION != 0
 184         else if (protocol_version < remote_protocol) {
 185                 if (our_sub)
 186                         protocol_version--;
 187         }
 188 #endif
 189
 190         if (protocol_version >= 30)
 191                 rl_nulls = 1;
 192
 193         return 0;
 194 }
 195
 196 int start_inband_exchange(int f_in, int f_out, const char *user, int argc, char *argv[])
 197 {
 198         int i, modlen;
 199         char line[BIGPATHBUFLEN];
 200         char *sargs[MAX_ARGS];
 201         int sargc = 0;
 202         char *p, *modname;
 203
 204         assert(argc > 0);
 205
 206         if (**argv == '/') {
 207                 rprintf(FERROR,
 208                         "ERROR: The remote path must start with a module name\n");
 209                 return -1;
 210         }
 211
 212         if (!(p = strchr(*argv, '/')))
 213                 modlen = strlen(*argv);
 214         else
 215                 modlen = p - *argv;
 216
 217         if (!(modname = new_array(char, modlen+1+1))) /* room for '/' & '\0' */
 218                 out_of_memory("start_inband_exchange");
 219         strlcpy(modname, *argv, modlen + 1);
 220         modname[modlen] = '/';
 221         modname[modlen+1] = '\0';
 222
 223         if (!user)
 224                 user = getenv("USER");
 225         if (!user)
 226                 user = getenv("LOGNAME");
 227
 228         if (exchange_protocols(f_in, f_out, line, sizeof line, 1) < 0)
 229                 return -1;
 230
 231         /* set daemon_over_rsh to false since we need to build the
 232          * true set of args passed through the rsh/ssh connection;
 233          * this is a no-op for direct-socket-connection mode */
 234         daemon_over_rsh = 0;
 235         server_options(sargs, &sargc);
 236
 237         if (sargc >= MAX_ARGS - 2)
 238                 goto arg_overflow;
 239
 240         sargs[sargc++] = ".";
 241
 242         while (argc > 0) {
 243                 if (sargc >= MAX_ARGS - 1) {
 244                   arg_overflow:
 245                         rprintf(FERROR, "internal: args[] overflowed in do_cmd()\n");
 246                         exit_cleanup(RERR_SYNTAX);
 247                 }
 248                 if (list_only && strncmp(*argv, modname, modlen) == 0
 249                  && argv[0][modlen] == '\0')
 250                         sargs[sargc++] = modname; /* we send "modname/" */
 251                 else
 252                         sargs[sargc++] = *argv;
 253                 argv++;
 254                 argc--;
 255         }
 256
 257         sargs[sargc] = NULL;
 258
 259         if (verbose > 1)
 260                 print_child_argv("sending daemon args:", sargs);
 261
 262         io_printf(f_out, "%.*s\n", modlen, modname);
 263
 264         /* Old servers may just drop the connection here,
 265          rather than sending a proper EXIT command.  Yuck. */
 266         kluge_around_eof = list_only && protocol_version < 25 ? 1 : 0;
 267
 268         while (1) {
 269                 if (!read_line_old(f_in, line, sizeof line)) {
 270                         rprintf(FERROR, "rsync: didn't get server startup line\n");
 271                         return -1;
 272                 }
 273
 274                 if (strncmp(line,"@RSYNCD: AUTHREQD ",18) == 0) {
 275                         auth_client(f_out, user, line+18);
 276                         continue;
 277                 }
 278
 279                 if (strcmp(line,"@RSYNCD: OK") == 0)
 280                         break;
 281
 282                 if (strcmp(line,"@RSYNCD: EXIT") == 0) {
 283                         /* This is sent by recent versions of the
 284                          * server to terminate the listing of modules.
 285                          * We don't want to go on and transfer
 286                          * anything; just exit. */
 287                         exit(0);
 288                 }
 289
 290                 if (strncmp(line, "@ERROR", 6) == 0) {
 291                         rprintf(FERROR, "%s\n", line);
 292                         /* This is always fatal; the server will now
 293                          * close the socket. */
 294                         return -1;
 295                 }
 296
 297                 /* This might be a MOTD line or a module listing, but there is
 298                  * no way to differentiate it.  The manpage mentions this. */
 299                 if (output_motd)
 300                         rprintf(FINFO, "%s\n", line);
 301         }
 302         kluge_around_eof = 0;
 303
 304         if (rl_nulls) {
 305                 for (i = 0; i < sargc; i++) {
 306                         write_sbuf(f_out, sargs[i]);
 307                         write_byte(f_out, 0);
 308                 }
 309                 write_byte(f_out, 0);
 310         } else {
 311                 for (i = 0; i < sargc; i++)
 312                         io_printf(f_out, "%s\n", sargs[i]);
 313                 write_sbuf(f_out, "\n");
 314         }
 315
 316         if (protocol_version < 23) {
 317                 if (protocol_version == 22 || !am_sender)
 318                         io_start_multiplex_in();
 319         }
 320
 321         free(modname);
 322
 323         return 0;
 324 }
 325
 326 static char *finish_pre_exec(pid_t pid, int fd, char *request,
 327                              int argc, char *argv[])
 328 {
 329         int j, status = -1;
 330
 331         if (!request)
 332                 request = "(NONE)";
 333
 334         write_buf(fd, request, strlen(request)+1);
 335         for (j = 0; j < argc; j++)
 336                 write_buf(fd, argv[j], strlen(argv[j])+1);
 337         write_byte(fd, 0);
 338
 339         close(fd);
 340
 341         if (wait_process(pid, &status, 0) < 0
 342          || !WIFEXITED(status) || WEXITSTATUS(status) != 0) {
 343                 char *e;
 344                 if (asprintf(&e, "pre-xfer exec returned failure (%d)%s%s\n",
 345                              status, status < 0 ? ": " : "",
 346                              status < 0 ? strerror(errno) : "") < 0)
 347                         out_of_memory("finish_pre_exec");
 348                 return e;
 349         }
 350         return NULL;
 351 }
 352
 353 static int read_arg_from_pipe(int fd, char *buf, int limit)
 354 {
 355         char *bp = buf, *eob = buf + limit - 1;
 356
 357         while (1) {
 358             if (read(fd, bp, 1) != 1)
 359                 return -1;
 360             if (*bp == '\0')
 361                 break;
 362             if (bp < eob)
 363                 bp++;
 364         }
 365         *bp = '\0';
 366
 367         return bp - buf;
 368 }
 369
 370 static int rsync_module(int f_in, int f_out, int i, char *addr, char *host)
 371 {
 372         int argc, opt_cnt;
 373         char **argv;
 374         char line[BIGPATHBUFLEN];
 375         uid_t uid = (uid_t)-2;  /* canonically "nobody" */
 376         gid_t gid = (gid_t)-2;
 377         char *p, *err_msg = NULL;
 378         char *name = lp_name(i);
 379         int use_chroot = lp_use_chroot(i);
 380         int ret, pre_exec_fd = -1;
 381         pid_t pre_exec_pid = 0;
 382         char *request = NULL;
 383
 384         if (!allow_access(addr, host, lp_hosts_allow(i), lp_hosts_deny(i))) {
 385                 rprintf(FLOG, "rsync denied on module %s from %s (%s)\n",
 386                         name, host, addr);
 387                 if (!lp_list(i))
 388                         io_printf(f_out, "@ERROR: Unknown module '%s'\n", name);
 389                 else {
 390                         io_printf(f_out,
 391                                   "@ERROR: access denied to %s from %s (%s)\n",
 392                                   name, host, addr);
 393                 }
 394                 return -1;
 395         }
 396
 397         if (am_daemon && am_server) {
 398                 rprintf(FLOG, "rsync allowed access on module %s from %s (%s)\n",
 399                         name, host, addr);
 400         }
 401
 402         if (!claim_connection(lp_lock_file(i), lp_max_connections(i))) {
 403                 if (errno) {
 404                         rsyserr(FLOG, errno, "failed to open lock file %s",
 405                                 lp_lock_file(i));
 406                         io_printf(f_out, "@ERROR: failed to open lock file\n");
 407                 } else {
 408                         rprintf(FLOG, "max connections (%d) reached\n",
 409                                 lp_max_connections(i));
 410                         io_printf(f_out, "@ERROR: max connections (%d) reached -- try again later\n",
 411                                 lp_max_connections(i));
 412                 }
 413                 return -1;
 414         }
 415
 416         auth_user = auth_server(f_in, f_out, i, host, addr, "@RSYNCD: AUTHREQD ");
 417
 418         if (!auth_user) {
 419                 io_printf(f_out, "@ERROR: auth failed on module %s\n", name);
 420                 return -1;
 421         }
 422
 423         module_id = i;
 424
 425         if (lp_read_only(i))
 426                 read_only = 1;
 427
 428         if (lp_transfer_logging(i) && !logfile_format)
 429                 logfile_format = lp_log_format(i);
 430         if (log_format_has(logfile_format, 'i'))
 431                 logfile_format_has_i = 1;
 432         if (logfile_format_has_i || log_format_has(logfile_format, 'o'))
 433                 logfile_format_has_o_or_i = 1;
 434
 435         am_root = (MY_UID() == 0);
 436
 437         if (am_root) {
 438                 p = lp_uid(i);
 439                 if (!name_to_uid(p, &uid)) {
 440                         if (!isDigit(p)) {
 441                                 rprintf(FLOG, "Invalid uid %s\n", p);
 442                                 io_printf(f_out, "@ERROR: invalid uid %s\n", p);
 443                                 return -1;
 444                         }
 445                         uid = atoi(p);
 446                 }
 447
 448                 p = lp_gid(i);
 449                 if (!name_to_gid(p, &gid)) {
 450                         if (!isDigit(p)) {
 451                                 rprintf(FLOG, "Invalid gid %s\n", p);
 452                                 io_printf(f_out, "@ERROR: invalid gid %s\n", p);
 453                                 return -1;
 454                         }
 455                         gid = atoi(p);
 456                 }
 457         }
 458
 459         /* TODO: If we're not root, but the configuration requests
 460          * that we change to some uid other than the current one, then
 461          * log a warning. */
 462
 463         /* TODO: Perhaps take a list of gids, and make them into the
 464          * supplementary groups. */
 465
 466         /* We do a push_dir() without actually calling chdir() in order
 467          * to make sure that the module's path is absolute.  After this
 468          * check, module_dir will be set to an absolute path. */
 469         module_dir = lp_path(i);
 470         strlcpy(line, curr_dir, sizeof line);
 471         if (!push_dir(module_dir, 1))
 472                 goto chdir_failed;
 473         if (strcmp(curr_dir, module_dir) != 0)
 474                 module_dir = strdup(curr_dir);
 475         push_dir(line, 1); /* Restore curr_dir. */
 476
 477         if (use_chroot || (module_dirlen = strlen(module_dir)) == 1) {
 478                 module_dirlen = 0;
 479                 set_filter_dir("/", 1);
 480         } else
 481                 set_filter_dir(module_dir, module_dirlen);
 482
 483         p = lp_filter(i);
 484         parse_rule(&server_filter_list, p, MATCHFLG_WORD_SPLIT,
 485                    XFLG_ABS_IF_SLASH);
 486
 487         p = lp_include_from(i);
 488         parse_filter_file(&server_filter_list, p, MATCHFLG_INCLUDE,
 489             XFLG_ABS_IF_SLASH | XFLG_OLD_PREFIXES | XFLG_FATAL_ERRORS);
 490
 491         p = lp_include(i);
 492         parse_rule(&server_filter_list, p,
 493                    MATCHFLG_INCLUDE | MATCHFLG_WORD_SPLIT,
 494                    XFLG_ABS_IF_SLASH | XFLG_OLD_PREFIXES);
 495
 496         p = lp_exclude_from(i);
 497         parse_filter_file(&server_filter_list, p, 0,
 498             XFLG_ABS_IF_SLASH | XFLG_OLD_PREFIXES | XFLG_FATAL_ERRORS);
 499
 500         p = lp_exclude(i);
 501         parse_rule(&server_filter_list, p, MATCHFLG_WORD_SPLIT,
 502                    XFLG_ABS_IF_SLASH | XFLG_OLD_PREFIXES);
 503
 504         log_init(1);
 505
 506 #ifdef HAVE_PUTENV
 507         if (*lp_prexfer_exec(i) || *lp_postxfer_exec(i)) {
 508                 char *modname, *modpath, *hostaddr, *hostname, *username;
 509                 int status;
 510                 if (asprintf(&modname, "RSYNC_MODULE_NAME=%s", name) < 0
 511                  || asprintf(&modpath, "RSYNC_MODULE_PATH=%s", module_dir) < 0
 512                  || asprintf(&hostaddr, "RSYNC_HOST_ADDR=%s", addr) < 0
 513                  || asprintf(&hostname, "RSYNC_HOST_NAME=%s", host) < 0
 514                  || asprintf(&username, "RSYNC_USER_NAME=%s", auth_user) < 0)
 515                         out_of_memory("rsync_module");
 516                 putenv(modname);
 517                 putenv(modpath);
 518                 putenv(hostaddr);
 519                 putenv(hostname);
 520                 putenv(username);
 521                 umask(orig_umask);
 522                 /* For post-xfer exec, fork a new process to run the rsync
 523                  * daemon while this process waits for the exit status and
 524                  * runs the indicated command at that point. */
 525                 if (*lp_postxfer_exec(i)) {
 526                         pid_t pid = fork();
 527                         if (pid < 0) {
 528                                 rsyserr(FLOG, errno, "fork failed");
 529                                 io_printf(f_out, "@ERROR: fork failed\n");
 530                                 return -1;
 531                         }
 532                         if (pid) {
 533                                 if (asprintf(&p, "RSYNC_PID=%ld", (long)pid) > 0)
 534                                         putenv(p);
 535                                 if (wait_process(pid, &status, 0) < 0)
 536                                         status = -1;
 537                                 if (asprintf(&p, "RSYNC_RAW_STATUS=%d", status) > 0)
 538                                         putenv(p);
 539                                 if (WIFEXITED(status))
 540                                         status = WEXITSTATUS(status);
 541                                 else
 542                                         status = -1;
 543                                 if (asprintf(&p, "RSYNC_EXIT_STATUS=%d", status) > 0)
 544                                         putenv(p);
 545                                 system(lp_postxfer_exec(i));
 546                                 _exit(status);
 547                         }
 548                 }
 549                 /* For pre-xfer exec, fork a child process to run the indicated
 550                  * command, though it first waits for the parent process to
 551                  * send us the user's request via a pipe. */
 552                 if (*lp_prexfer_exec(i)) {
 553                         int fds[2];
 554                         if (asprintf(&p, "RSYNC_PID=%ld", (long)getpid()) > 0)
 555                                 putenv(p);
 556                         if (pipe(fds) < 0 || (pre_exec_pid = fork()) < 0) {
 557                                 rsyserr(FLOG, errno, "pre-xfer exec preparation failed");
 558                                 io_printf(f_out, "@ERROR: pre-xfer exec preparation failed\n");
 559                                 return -1;
 560                         }
 561                         if (pre_exec_pid == 0) {
 562                                 char buf[BIGPATHBUFLEN];
 563                                 int j, len;
 564                                 close(fds[1]);
 565                                 set_blocking(fds[0]);
 566                                 len = read_arg_from_pipe(fds[0], buf, BIGPATHBUFLEN);
 567                                 if (len <= 0)
 568                                         _exit(1);
 569                                 if (asprintf(&p, "RSYNC_REQUEST=%s", buf) > 0)
 570                                         putenv(p);
 571                                 for (j = 0; ; j++) {
 572                                         len = read_arg_from_pipe(fds[0], buf,
 573                                                                  BIGPATHBUFLEN);
 574                                         if (len <= 0) {
 575                                                 if (!len)
 576                                                         break;
 577                                                 _exit(1);
 578                                         }
 579                                         if (asprintf(&p, "RSYNC_ARG%d=%s", j, buf) > 0)
 580                                                 putenv(p);
 581                                 }
 582                                 close(fds[0]);
 583                                 close(STDIN_FILENO);
 584                                 close(STDOUT_FILENO);
 585                                 status = system(lp_prexfer_exec(i));
 586                                 if (!WIFEXITED(status))
 587                                         _exit(1);
 588                                 _exit(WEXITSTATUS(status));
 589                         }
 590                         close(fds[0]);
 591                         set_blocking(fds[1]);
 592                         pre_exec_fd = fds[1];
 593                 }
 594                 umask(0);
 595         }
 596 #endif
 597
 598         if (use_chroot) {
 599                 /*
 600                  * XXX: The 'use chroot' flag is a fairly reliable
 601                  * source of confusion, because it fails under two
 602                  * important circumstances: running as non-root,
 603                  * running on Win32 (or possibly others).  On the
 604                  * other hand, if you are running as root, then it
 605                  * might be better to always use chroot.
 606                  *
 607                  * So, perhaps if we can't chroot we should just issue
 608                  * a warning, unless a "require chroot" flag is set,
 609                  * in which case we fail.
 610                  */
 611                 if (chroot(module_dir)) {
 612                         rsyserr(FLOG, errno, "chroot %s failed", module_dir);
 613                         io_printf(f_out, "@ERROR: chroot failed\n");
 614                         return -1;
 615                 }
 616                 if (!push_dir("/", 0))
 617                         goto chdir_failed;
 618         } else {
 619                 if (!push_dir(module_dir, 0)) {
 620                   chdir_failed:
 621                         rsyserr(FLOG, errno, "chdir %s failed\n", module_dir);
 622                         io_printf(f_out, "@ERROR: chdir failed\n");
 623                         return -1;
 624                 }
 625                 sanitize_paths = 1;
 626         }
 627
 628         if ((munge_symlinks = lp_munge_symlinks(i)) < 0)
 629                 munge_symlinks = !use_chroot;
 630         if (munge_symlinks) {
 631                 STRUCT_STAT st;
 632                 if (stat(SYMLINK_PREFIX, &st) == 0 && S_ISDIR(st.st_mode)) {
 633                         rprintf(FLOG, "Symlink munging is unsupported when a %s directory exists.\n",
 634                                 SYMLINK_PREFIX);
 635                         io_printf(f_out, "@ERROR: daemon security issue -- contact admin\n", name);
 636                         exit_cleanup(RERR_UNSUPPORTED);
 637                 }
 638         }
 639
 640         if (am_root) {
 641                 /* XXXX: You could argue that if the daemon is started
 642                  * by a non-root user and they explicitly specify a
 643                  * gid, then we should try to change to that gid --
 644                  * this could be possible if it's already in their
 645                  * supplementary groups. */
 646
 647                 /* TODO: Perhaps we need to document that if rsyncd is
 648                  * started by somebody other than root it will inherit
 649                  * all their supplementary groups. */
 650
 651                 if (setgid(gid)) {
 652                         rsyserr(FLOG, errno, "setgid %d failed", (int)gid);
 653                         io_printf(f_out, "@ERROR: setgid failed\n");
 654                         return -1;
 655                 }
 656 #ifdef HAVE_SETGROUPS
 657                 /* Get rid of any supplementary groups this process
 658                  * might have inheristed. */
 659                 if (setgroups(1, &gid)) {
 660                         rsyserr(FLOG, errno, "setgroups failed");
 661                         io_printf(f_out, "@ERROR: setgroups failed\n");
 662                         return -1;
 663                 }
 664 #endif
 665
 666                 if (setuid(uid)) {
 667                         rsyserr(FLOG, errno, "setuid %d failed", (int)uid);
 668                         io_printf(f_out, "@ERROR: setuid failed\n");
 669                         return -1;
 670                 }
 671
 672                 am_root = (MY_UID() == 0);
 673         }
 674
 675         if (lp_temp_dir(i) && *lp_temp_dir(i)) {
 676                 tmpdir = lp_temp_dir(i);
 677                 if (strlen(tmpdir) >= MAXPATHLEN - 10) {
 678                         rprintf(FLOG,
 679                                 "the 'temp dir' value for %s is WAY too long -- ignoring.\n",
 680                                 name);
 681                         tmpdir = NULL;
 682                 }
 683         }
 684
 685         io_printf(f_out, "@RSYNCD: OK\n");
 686
 687         opt_cnt = read_args(f_in, name, line, sizeof line, rl_nulls, &argv, &argc, &request);
 688
 689         if (pre_exec_pid) {
 690                 err_msg = finish_pre_exec(pre_exec_pid, pre_exec_fd, request,
 691                                           opt_cnt, argv);
 692         }
 693
 694         verbose = 0; /* future verbosity is controlled by client options */
 695         ret = parse_arguments(&argc, (const char ***) &argv, 0);
 696         am_server = 1; /* Don't let someone try to be tricky. */
 697         if (lp_ignore_errors(module_id))
 698                 ignore_errors = 1;
 699         if (write_batch < 0)
 700                 dry_run = 1;
 701
 702         if (lp_fake_super(i))
 703                 am_root = -1;
 704         else if (am_root < 0) /* Treat --fake-super from client as --super. */
 705                 am_root = 2;
 706
 707         if (filesfrom_fd == 0)
 708                 filesfrom_fd = f_in;
 709
 710         if (request) {
 711                 if (*auth_user) {
 712                         rprintf(FLOG, "rsync %s %s from %s@%s (%s)\n",
 713                                 am_sender ? "on" : "to",
 714                                 request, auth_user, host, addr);
 715                 } else {
 716                         rprintf(FLOG, "rsync %s %s from %s (%s)\n",
 717                                 am_sender ? "on" : "to",
 718                                 request, host, addr);
 719                 }
 720                 free(request);
 721         }
 722
 723 #ifndef DEBUG
 724         /* don't allow the logs to be flooded too fast */
 725         if (verbose > lp_max_verbosity(i))
 726                 verbose = lp_max_verbosity(i);
 727 #endif
 728
 729         if (protocol_version < 23
 730             && (protocol_version == 22 || am_sender))
 731                 io_start_multiplex_out();
 732         else if (!ret || err_msg) {
 733                 /* We have to get I/O multiplexing started so that we can
 734                  * get the error back to the client.  This means getting
 735                  * the protocol setup finished first in later versions. */
 736                 setup_protocol(f_out, f_in);
 737                 if (!am_sender) {
 738                         /* Since we failed in our option parsing, we may not
 739                          * have finished parsing that the client sent us a
 740                          * --files-from option, so look for it manually.
 741                          * Without this, the socket would be in the wrong
 742                          * state for the upcoming error message. */
 743                         if (!files_from) {
 744                                 int i;
 745                                 for (i = 0; i < argc; i++) {
 746                                         if (strncmp(argv[i], "--files-from", 12) == 0) {
 747                                                 files_from = "";
 748                                                 break;
 749                                         }
 750                                 }
 751                         }
 752                         if (files_from)
 753                                 write_byte(f_out, 0);
 754                 }
 755                 io_start_multiplex_out();
 756         }
 757
 758         if (!ret || err_msg) {
 759                 if (err_msg)
 760                         rwrite(FERROR, err_msg, strlen(err_msg), 0);
 761                 else
 762                         option_error();
 763                 msleep(400);
 764                 exit_cleanup(RERR_UNSUPPORTED);
 765         }
 766
 767         if (lp_timeout(i) && lp_timeout(i) > io_timeout)
 768                 set_io_timeout(lp_timeout(i));
 769
 770         /* If we have some incoming/outgoing chmod changes, append them to
 771          * any user-specified changes (making our changes have priority).
 772          * We also get a pointer to just our changes so that a receiver
 773          * process can use them separately if --perms wasn't specified. */
 774         if (am_sender)
 775                 p = lp_outgoing_chmod(i);
 776         else
 777                 p = lp_incoming_chmod(i);
 778         if (*p && !(daemon_chmod_modes = parse_chmod(p, &chmod_modes))) {
 779                 rprintf(FLOG, "Invalid \"%sing chmod\" directive: %s\n",
 780                         am_sender ? "outgo" : "incom", p);
 781         }
 782
 783         start_server(f_in, f_out, argc, argv);
 784
 785         return 0;
 786 }
 787
 788 /* send a list of available modules to the client. Don't list those
 789    with "list = False". */
 790 static void send_listing(int fd)
 791 {
 792         int n = lp_numservices();
 793         int i;
 794
 795         for (i = 0; i < n; i++) {
 796                 if (lp_list(i))
 797                         io_printf(fd, "%-15s\t%s\n", lp_name(i), lp_comment(i));
 798         }
 799
 800         if (protocol_version >= 25)
 801                 io_printf(fd,"@RSYNCD: EXIT\n");
 802 }
 803
 804 /* this is called when a connection is established to a client
 805    and we want to start talking. The setup of the system is done from
 806    here */
 807 int start_daemon(int f_in, int f_out)
 808 {
 809         char line[1024];
 810         char *addr, *host;
 811         int i;
 812
 813         io_set_sock_fds(f_in, f_out);
 814
 815         /* We must load the config file before calling any function that
 816          * might cause log-file output to occur.  This ensures that the
 817          * "log file" param gets honored for the 2 non-forked use-cases
 818          * (when rsync is run by init and run by a remote shell). */
 819         if (!lp_load(config_file, 0))
 820                 exit_cleanup(RERR_SYNTAX);
 821
 822         addr = client_addr(f_in);
 823         host = client_name(f_in);
 824         rprintf(FLOG, "connect from %s (%s)\n", host, addr);
 825
 826         if (!am_server) {
 827                 set_socket_options(f_in, "SO_KEEPALIVE");
 828                 if (sockopts)
 829                         set_socket_options(f_in, sockopts);
 830                 else
 831                         set_socket_options(f_in, lp_socket_options());
 832                 set_nonblocking(f_in);
 833         }
 834
 835         if (exchange_protocols(f_in, f_out, line, sizeof line, 0) < 0)
 836                 return -1;
 837
 838         line[0] = 0;
 839         if (!read_line_old(f_in, line, sizeof line))
 840                 return -1;
 841
 842         if (!*line || strcmp(line, "#list") == 0) {
 843                 rprintf(FLOG, "module-list request from %s (%s)\n",
 844                         host, addr);
 845                 send_listing(f_out);
 846                 return -1;
 847         }
 848
 849         if (*line == '#') {
 850                 /* it's some sort of command that I don't understand */
 851                 io_printf(f_out, "@ERROR: Unknown command '%s'\n", line);
 852                 return -1;
 853         }
 854
 855         if ((i = lp_number(line)) < 0) {
 856                 rprintf(FLOG, "unknown module '%s' tried from %s (%s)\n",
 857                         line, host, addr);
 858                 io_printf(f_out, "@ERROR: Unknown module '%s'\n", line);
 859                 return -1;
 860         }
 861
 862 #ifdef HAVE_SIGACTION
 863         sigact.sa_flags = SA_NOCLDSTOP;
 864 #endif
 865         SIGACTION(SIGCHLD, remember_children);
 866
 867         return rsync_module(f_in, f_out, i, addr, host);
 868 }
 869
 870 static void create_pid_file(void)
 871 {
 872         char *pid_file = lp_pid_file();
 873         char pidbuf[16];
 874         pid_t pid = getpid();
 875         int fd;
 876
 877         if (!pid_file || !*pid_file)
 878                 return;
 879
 880         cleanup_set_pid(pid);
 881         if ((fd = do_open(pid_file, O_WRONLY|O_CREAT|O_EXCL, 0666 & ~orig_umask)) == -1) {
 882                 cleanup_set_pid(0);
 883                 fprintf(stderr, "failed to create pid file %s: %s\n", pid_file, strerror(errno));
 884                 rsyserr(FLOG, errno, "failed to create pid file %s", pid_file);
 885                 exit_cleanup(RERR_FILEIO);
 886         }
 887         snprintf(pidbuf, sizeof pidbuf, "%ld\n", (long)pid);
 888         write(fd, pidbuf, strlen(pidbuf));
 889         close(fd);
 890 }
 891
 892 /* Become a daemon, discarding the controlling terminal. */
 893 static void become_daemon(void)
 894 {
 895         int i;
 896         pid_t pid = fork();
 897
 898         if (pid) {
 899                 if (pid < 0) {
 900                         fprintf(stderr, "failed to fork: %s\n", strerror(errno));
 901                         exit_cleanup(RERR_FILEIO);
 902                 }
 903                 _exit(0);
 904         }
 905
 906         create_pid_file();
 907
 908         /* detach from the terminal */
 909 #ifdef HAVE_SETSID
 910         setsid();
 911 #elif defined TIOCNOTTY
 912         i = open("/dev/tty", O_RDWR);
 913         if (i >= 0) {
 914                 ioctl(i, (int)TIOCNOTTY, (char *)0);
 915                 close(i);
 916         }
 917 #endif
 918         /* make sure that stdin, stdout an stderr don't stuff things
 919          * up (library functions, for example) */
 920         for (i = 0; i < 3; i++) {
 921                 close(i);
 922                 open("/dev/null", O_RDWR);
 923         }
 924 }
 925
 926 int daemon_main(void)
 927 {
 928         if (!config_file) {
 929                 if (am_server && am_root <= 0)
 930                         config_file = RSYNCD_USERCONF;
 931                 else
 932                         config_file = RSYNCD_SYSCONF;
 933         }
 934
 935         if (is_a_socket(STDIN_FILENO)) {
 936                 int i;
 937
 938                 /* we are running via inetd - close off stdout and
 939                  * stderr so that library functions (and getopt) don't
 940                  * try to use them. Redirect them to /dev/null */
 941                 for (i = 1; i < 3; i++) {
 942                         close(i);
 943                         open("/dev/null", O_RDWR);
 944                 }
 945
 946                 return start_daemon(STDIN_FILENO, STDIN_FILENO);
 947         }
 948
 949         if (!lp_load(config_file, 1)) {
 950                 fprintf(stderr, "Failed to parse config file: %s\n", config_file);
 951                 exit_cleanup(RERR_SYNTAX);
 952         }
 953
 954         if (no_detach)
 955                 create_pid_file();
 956         else
 957                 become_daemon();
 958
 959         if (rsync_port == 0 && (rsync_port = lp_rsync_port()) == 0)
 960                 rsync_port = RSYNC_PORT;
 961         if (bind_address == NULL && *lp_bind_address())
 962                 bind_address = lp_bind_address();
 963
 964         log_init(0);
 965
 966         rprintf(FLOG, "rsyncd version %s starting, listening on port %d\n",
 967                 RSYNC_VERSION, rsync_port);
 968         /* TODO: If listening on a particular address, then show that
 969          * address too.  In fact, why not just do inet_ntop on the
 970          * local address??? */
 971
 972         start_accept_loop(rsync_port, start_daemon);
 973         return -1;
 974 }