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clientserver.c

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00001 /* -*- c-file-style: "linux"; -*-
00002  * 
00003  * Copyright (C) 1998-2001 by Andrew Tridgell <tridge@samba.org>
00004  * Copyright (C) 2001-2002 by Martin Pool <mbp@samba.org>
00005  * 
00006  * This program is free software; you can redistribute it and/or modify
00007  * it under the terms of the GNU General Public License as published by
00008  * the Free Software Foundation; either version 2 of the License, or
00009  * (at your option) any later version.
00010  * 
00011  * This program is distributed in the hope that it will be useful,
00012  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00013  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00014  * GNU General Public License for more details.
00015  * 
00016  * You should have received a copy of the GNU General Public License
00017  * along with this program; if not, write to the Free Software
00018  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
00019  */
00020 
00021 /**
00022  * @file
00023  *
00024  * The socket based protocol for setting up a connection with
00025  * rsyncd.
00026  **/
00027 
00028 #include "rsync.h"
00029 
00030 extern int module_id;
00031 extern int read_only;
00032 extern int verbose;
00033 extern int rsync_port;
00034 char *auth_user;
00035 extern int sanitize_paths;
00036 
00037 /**
00038  * Run a client connected to an rsyncd.  The alternative to this
00039  * function for remote-shell connections is do_cmd().
00040  *
00041  * After negotiating which module to use and reading the server's
00042  * motd, this hands over to client_run().  Telling the server the
00043  * module will cause it to chroot/setuid/etc.
00044  *
00045  * Instead of doing a transfer, the client may at this stage instead
00046  * get a listing of remote modules and exit.
00047  *
00048  * @return -1 for error in startup, or the result of client_run().
00049  * Either way, it eventually gets passed to exit_cleanup().
00050  **/
00051 int start_socket_client(char *host, char *path, int argc, char *argv[])
00052 {
00053         int fd, i;
00054         char *sargs[MAX_ARGS];
00055         int sargc=0;
00056         char line[MAXPATHLEN];
00057         char *p, *user=NULL;
00058         extern int remote_version;
00059         extern int am_sender;
00060         extern char *shell_cmd;
00061         extern int list_only;
00062         extern int kludge_around_eof;
00063         extern char *bind_address;
00064         extern int default_af_hint;
00065        
00066         if (argc == 0 && !am_sender) {
00067                 extern int list_only;
00068                 list_only = 1;
00069         }
00070 
00071         /* This is just a friendliness enhancement: if the connection
00072          * is to an rsyncd then there is no point specifying the -e option.
00073          * Note that this is only set if the -e was explicitly specified,
00074          * not if the environment variable just happens to be set.
00075          * See http://lists.samba.org/pipermail/rsync/2000-September/002744.html
00076          */
00077         if (shell_cmd) {
00078                 rprintf(FINFO, "WARNING: --rsh or -e option ignored when "
00079                         "connecting to rsync daemon\n");
00080                 /* continue */
00081         }
00082         
00083         if (*path == '/') {
00084                 rprintf(FERROR,"ERROR: The remote path must start with a module name not a /\n");
00085                 return -1;
00086         }
00087 
00088         p = strchr(host, '@');
00089         if (p) {
00090                 user = host;
00091                 host = p+1;
00092                 *p = 0;
00093         }
00094 
00095         if (!user) user = getenv("USER");
00096         if (!user) user = getenv("LOGNAME");
00097 
00098         if (verbose >= 2) {
00099                 /* FIXME: If we're going to use a socket program for
00100                  * testing, then this message is wrong.  We need to
00101                  * say something like "(except really using %s)" */
00102                 rprintf(FINFO, "opening tcp connection to %s port %d\n",
00103                         host, rsync_port);
00104         }
00105         fd = open_socket_out_wrapped (host, rsync_port, bind_address,
00106                                       default_af_hint);
00107         if (fd == -1) {
00108                 exit_cleanup(RERR_SOCKETIO);
00109         }
00110         
00111         server_options(sargs,&sargc);
00112 
00113         sargs[sargc++] = ".";
00114 
00115         if (path && *path) 
00116                 sargs[sargc++] = path;
00117 
00118         sargs[sargc] = NULL;
00119 
00120         io_printf(fd,"@RSYNCD: %d\n", PROTOCOL_VERSION);
00121 
00122         if (!read_line(fd, line, sizeof(line)-1)) {
00123                 rprintf(FERROR, "rsync: did not see server greeting\n");
00124                 return -1;
00125         }
00126 
00127         if (sscanf(line,"@RSYNCD: %d", &remote_version) != 1) {
00128                 /* note that read_line strips of \n or \r */
00129                 rprintf(FERROR, "rsync: server sent \"%s\" rather than greeting\n",
00130                         line);
00131                 return -1;
00132         }
00133 
00134         p = strchr(path,'/');
00135         if (p) *p = 0;
00136         io_printf(fd,"%s\n",path);
00137         if (p) *p = '/';
00138 
00139         /* Old servers may just drop the connection here,
00140          rather than sending a proper EXIT command.  Yuck. */
00141         kludge_around_eof = list_only && (remote_version < 25);
00142 
00143         while (1) {
00144                 if (!read_line(fd, line, sizeof(line)-1)) {
00145                         rprintf(FERROR, "rsync: didn't get server startup line\n");
00146                         return -1;
00147                 }
00148 
00149                 if (strncmp(line,"@RSYNCD: AUTHREQD ",18) == 0) {
00150                         auth_client(fd, user, line+18);
00151                         continue;
00152                 }
00153 
00154                 if (strcmp(line,"@RSYNCD: OK") == 0) break;
00155 
00156                 if (strcmp(line,"@RSYNCD: EXIT") == 0) {
00157                         /* This is sent by recent versions of the
00158                          * server to terminate the listing of modules.
00159                          * We don't want to go on and transfer
00160                          * anything; just exit. */
00161                         exit(0);
00162                 }
00163 
00164                 if (strncmp(line, "@ERROR", 6) == 0) {
00165                         rprintf(FERROR,"%s\n", line);
00166                         /* This is always fatal; the server will now
00167                          * close the socket. */
00168                         return RERR_STARTCLIENT;
00169                 } else {
00170                         rprintf(FINFO,"%s\n", line);
00171                 }
00172         }
00173         kludge_around_eof = False;
00174 
00175         for (i=0;i<sargc;i++) {
00176                 io_printf(fd,"%s\n", sargs[i]);
00177         }
00178         io_printf(fd,"\n");
00179 
00180         if (remote_version < 23) {
00181                 if (remote_version == 22 || (remote_version > 17 && !am_sender))
00182                         io_start_multiplex_in(fd);
00183         }
00184 
00185         return client_run(fd, fd, -1, argc, argv);
00186 }
00187 
00188 
00189 
00190 static int rsync_module(int fd, int i)
00191 {
00192         int argc=0;
00193         char *argv[MAX_ARGS];
00194         char **argp;
00195         char line[MAXPATHLEN];
00196         uid_t uid = (uid_t)-2;  /* canonically "nobody" */
00197         gid_t gid = (gid_t)-2;
00198         char *p;
00199         char *addr = client_addr(fd);
00200         char *host = client_name(fd);
00201         char *name = lp_name(i);
00202         int use_chroot = lp_use_chroot(i);
00203         int start_glob=0;
00204         int ret;
00205         char *request=NULL;
00206         extern int am_sender;
00207         extern int remote_version;
00208         extern int am_root;
00209 
00210         if (!allow_access(addr, host, lp_hosts_allow(i), lp_hosts_deny(i))) {
00211                 rprintf(FERROR,"rsync denied on module %s from %s (%s)\n",
00212                         name, host, addr);
00213                 io_printf(fd,"@ERROR: access denied to %s from %s (%s)\n",
00214                           name, host, addr);
00215                 return -1;
00216         }
00217 
00218         if (!claim_connection(lp_lock_file(i), lp_max_connections(i))) {
00219                 if (errno) {
00220                         rprintf(FERROR,"failed to open lock file %s : %s\n",
00221                                 lp_lock_file(i), strerror(errno));
00222                         io_printf(fd,"@ERROR: failed to open lock file %s : %s\n",
00223                                   lp_lock_file(i), strerror(errno));
00224                 } else {
00225                         rprintf(FERROR,"max connections (%d) reached\n",
00226                                 lp_max_connections(i));
00227                         io_printf(fd,"@ERROR: max connections (%d) reached - try again later\n", lp_max_connections(i));
00228                 }
00229                 return -1;
00230         }
00231 
00232         
00233         auth_user = auth_server(fd, i, addr, "@RSYNCD: AUTHREQD ");
00234 
00235         if (!auth_user) {
00236                 rprintf(FERROR,"auth failed on module %s from %s (%s)\n",
00237                         name, client_name(fd), client_addr(fd));
00238                 io_printf(fd,"@ERROR: auth failed on module %s\n",name);
00239                 return -1;              
00240         }
00241 
00242         module_id = i;
00243 
00244         am_root = (getuid() == 0);
00245 
00246         if (am_root) {
00247                 p = lp_uid(i);
00248                 if (!name_to_uid(p, &uid)) {
00249                         if (!isdigit(* (unsigned char *) p)) {
00250                                 rprintf(FERROR,"Invalid uid %s\n", p);
00251                                 io_printf(fd,"@ERROR: invalid uid %s\n", p);
00252                                 return -1;
00253                         } 
00254                         uid = atoi(p);
00255                 }
00256 
00257                 p = lp_gid(i);
00258                 if (!name_to_gid(p, &gid)) {
00259                         if (!isdigit(* (unsigned char *) p)) {
00260                                 rprintf(FERROR,"Invalid gid %s\n", p);
00261                                 io_printf(fd,"@ERROR: invalid gid %s\n", p);
00262                                 return -1;
00263                         } 
00264                         gid = atoi(p);
00265                 }
00266         }
00267         
00268         /* TODO: If we're not root, but the configuration requests
00269          * that we change to some uid other than the current one, then
00270          * log a warning. */
00271 
00272         /* TODO: Perhaps take a list of gids, and make them into the
00273          * supplementary groups. */
00274 
00275         p = lp_include_from(i);
00276         add_exclude_file(p, 1, 1);
00277 
00278         p = lp_include(i);
00279         add_include_line(p);
00280 
00281         p = lp_exclude_from(i);
00282         add_exclude_file(p, 1, 0);
00283 
00284         p = lp_exclude(i);
00285         add_exclude_line(p);
00286 
00287         log_init();
00288 
00289         if (use_chroot) {
00290                 /*
00291                  * XXX: The 'use chroot' flag is a fairly reliable
00292                  * source of confusion, because it fails under two
00293                  * important circumstances: running as non-root,
00294                  * running on Win32 (or possibly others).  On the
00295                  * other hand, if you are running as root, then it
00296                  * might be better to always use chroot.
00297                  *
00298                  * So, perhaps if we can't chroot we should just issue
00299                  * a warning, unless a "require chroot" flag is set,
00300                  * in which case we fail.
00301                  */
00302                 if (chroot(lp_path(i))) {
00303                         rsyserr(FERROR, errno, "chroot %s failed", lp_path(i));
00304                         io_printf(fd,"@ERROR: chroot failed\n");
00305                         return -1;
00306                 }
00307 
00308                 if (!push_dir("/", 0)) {
00309                         rsyserr(FERROR, errno, "chdir %s failed\n", lp_path(i));
00310                         io_printf(fd,"@ERROR: chdir failed\n");
00311                         return -1;
00312                 }
00313 
00314         } else {
00315                 if (!push_dir(lp_path(i), 0)) {
00316                         rsyserr(FERROR, errno, "chdir %s failed\n", lp_path(i));
00317                         io_printf(fd,"@ERROR: chdir failed\n");
00318                         return -1;
00319                 }
00320                 sanitize_paths = 1;
00321         }
00322 
00323         if (am_root) {
00324 #ifdef HAVE_SETGROUPS
00325                 /* Get rid of any supplementary groups this process
00326                  * might have inheristed. */
00327                 if (setgroups(0, NULL)) {
00328                         rsyserr(FERROR, errno, "setgroups failed");
00329                         io_printf(fd, "@ERROR: setgroups failed\n");
00330                         return -1;
00331                 }
00332 #endif
00333 
00334                 /* XXXX: You could argue that if the daemon is started
00335                  * by a non-root user and they explicitly specify a
00336                  * gid, then we should try to change to that gid --
00337                  * this could be possible if it's already in their
00338                  * supplementary groups. */
00339 
00340                 /* TODO: Perhaps we need to document that if rsyncd is
00341                  * started by somebody other than root it will inherit
00342                  * all their supplementary groups. */
00343 
00344                 if (setgid(gid)) {
00345                         rsyserr(FERROR, errno, "setgid %d failed", (int) gid);
00346                         io_printf(fd,"@ERROR: setgid failed\n");
00347                         return -1;
00348                 }
00349 
00350                 if (setuid(uid)) {
00351                         rsyserr(FERROR, errno, "setuid %d failed", (int) uid);
00352                         io_printf(fd,"@ERROR: setuid failed\n");
00353                         return -1;
00354                 }
00355 
00356                 am_root = (getuid() == 0);
00357         }
00358 
00359         io_printf(fd,"@RSYNCD: OK\n");
00360 
00361         argv[argc++] = "rsyncd";
00362 
00363         while (1) {
00364                 if (!read_line(fd, line, sizeof(line)-1)) {
00365                         return -1;
00366                 }
00367 
00368                 if (!*line) break;
00369 
00370                 p = line;
00371 
00372                 argv[argc] = strdup(p);
00373                 if (!argv[argc]) {
00374                         return -1;
00375                 }
00376 
00377                 if (start_glob) {
00378                         if (start_glob == 1) {
00379                                 request = strdup(p);
00380                                 start_glob++;
00381                         }
00382                         glob_expand(name, argv, &argc, MAX_ARGS);
00383                 } else {
00384                         argc++;
00385                 }
00386 
00387                 if (strcmp(line,".") == 0) {
00388                         start_glob = 1;
00389                 }
00390 
00391                 if (argc == MAX_ARGS) {
00392                         return -1;
00393                 }
00394         }
00395 
00396         if (sanitize_paths) {
00397                 /*
00398                  * Note that this is applied to all parameters, whether or not
00399                  *    they are filenames, but no other legal parameters contain
00400                  *    the forms that need to be sanitized so it doesn't hurt;
00401                  *    it is not known at this point which parameters are files
00402                  *    and which aren't.
00403                  */
00404                 for (i = 1; i < argc; i++) {
00405                         sanitize_path(argv[i], NULL);
00406                 }
00407         }
00408 
00409         argp = argv;
00410         ret = parse_arguments(&argc, (const char ***) &argp, 0);
00411 
00412         if (request) {
00413                 if (*auth_user) {
00414                         rprintf(FINFO,"rsync %s %s from %s@%s (%s)\n",
00415                                 am_sender?"on":"to",
00416                                 request, auth_user, host, addr);
00417                 } else {
00418                         rprintf(FINFO,"rsync %s %s from %s (%s)\n",
00419                                 am_sender?"on":"to",
00420                                 request, host, addr);
00421                 }
00422                 free(request);
00423         }
00424 
00425 #ifndef DEBUG
00426         /* don't allow the logs to be flooded too fast */
00427         if (verbose > 1) verbose = 1;
00428 #endif
00429 
00430         if (remote_version < 23) {
00431                 if (remote_version == 22 || (remote_version > 17 && am_sender))
00432                         io_start_multiplex_out(fd);
00433         }
00434         
00435         /* For later protocol versions, we don't start multiplexing
00436          * until we've configured nonblocking in start_server.  That
00437          * means we're in a sticky situation now: there's no way to
00438          * convey errors to the client. */
00439 
00440         /* FIXME: Hold off on reporting option processing errors until
00441          * we've set up nonblocking and multiplexed IO and can get the
00442          * message back to them. */
00443         if (!ret) {
00444                 option_error();
00445                 exit_cleanup(RERR_UNSUPPORTED);
00446         }
00447 
00448         if (lp_timeout(i)) {
00449                 extern int io_timeout;
00450                 io_timeout = lp_timeout(i);
00451         }
00452 
00453         start_server(fd, fd, argc, argp);
00454 
00455         return 0;
00456 }
00457 
00458 /* send a list of available modules to the client. Don't list those
00459    with "list = False". */
00460 static void send_listing(int fd)
00461 {
00462         int n = lp_numservices();
00463         int i;
00464         extern int remote_version;
00465 
00466         for (i=0;i<n;i++)
00467                 if (lp_list(i))
00468                     io_printf(fd, "%-15s\t%s\n", lp_name(i), lp_comment(i));
00469 
00470         if (remote_version >= 25)
00471                 io_printf(fd,"@RSYNCD: EXIT\n");
00472 }
00473 
00474 /* this is called when a socket connection is established to a client
00475    and we want to start talking. The setup of the system is done from
00476    here */
00477 static int start_daemon(int fd)
00478 {
00479         char line[200];
00480         char *motd;
00481         int i = -1;
00482         extern char *config_file;
00483         extern int remote_version;
00484 
00485         if (!lp_load(config_file, 0)) {
00486                 exit_cleanup(RERR_SYNTAX);
00487         }
00488 
00489         set_socket_options(fd,"SO_KEEPALIVE");
00490         set_socket_options(fd,lp_socket_options());
00491         set_nonblocking(fd);
00492 
00493         io_printf(fd,"@RSYNCD: %d\n", PROTOCOL_VERSION);
00494 
00495         motd = lp_motd_file();
00496         if (motd && *motd) {
00497                 FILE *f = fopen(motd,"r");
00498                 while (f && !feof(f)) {
00499                         int len = fread(line, 1, sizeof(line)-1, f);
00500                         if (len > 0) {
00501                                 line[len] = 0;
00502                                 io_printf(fd,"%s", line);
00503                         }
00504                 }
00505                 if (f) fclose(f);
00506                 io_printf(fd,"\n");
00507         }
00508 
00509         if (!read_line(fd, line, sizeof(line)-1)) {
00510                 return -1;
00511         }
00512 
00513         if (sscanf(line,"@RSYNCD: %d", &remote_version) != 1) {
00514                 io_printf(fd,"@ERROR: protocol startup error\n");
00515                 return -1;
00516         }       
00517 
00518         while (i == -1) {
00519                 line[0] = 0;
00520                 if (!read_line(fd, line, sizeof(line)-1)) {
00521                         return -1;
00522                 }
00523 
00524                 if (!*line || strcmp(line,"#list")==0) {
00525                         send_listing(fd);
00526                         return -1;
00527                 } 
00528 
00529                 if (*line == '#') {
00530                         /* it's some sort of command that I don't understand */
00531                         io_printf(fd,"@ERROR: Unknown command '%s'\n", line);
00532                         return -1;
00533                 }
00534 
00535                 i = lp_number(line);
00536                 if (i == -1) {
00537                         io_printf(fd,"@ERROR: Unknown module '%s'\n", line);
00538                         return -1;
00539                 }
00540         }
00541 
00542         return rsync_module(fd, i);
00543 }
00544 
00545 
00546 int daemon_main(void)
00547 {
00548         extern char *config_file;
00549         extern int orig_umask;
00550         char *pid_file;
00551         extern int no_detach;
00552 
00553         if (is_a_socket(STDIN_FILENO)) {
00554                 int i;
00555 
00556                 /* we are running via inetd - close off stdout and
00557                    stderr so that library functions (and getopt) don't
00558                    try to use them. Redirect them to /dev/null */
00559                 for (i=1;i<3;i++) {
00560                         close(i); 
00561                         open("/dev/null", O_RDWR);
00562                 }
00563 
00564                 return start_daemon(STDIN_FILENO);
00565         }
00566 
00567         if (!no_detach)
00568             become_daemon();
00569 
00570         if (!lp_load(config_file, 1)) {
00571                 exit_cleanup(RERR_SYNTAX);
00572         }
00573 
00574         log_init();
00575 
00576         rprintf(FINFO, "rsyncd version %s starting, listening on port %d\n",
00577                 RSYNC_VERSION,
00578                 rsync_port);
00579         /* TODO: If listening on a particular address, then show that
00580          * address too.  In fact, why not just do inet_ntop on the
00581          * local address??? */
00582 
00583         if (((pid_file = lp_pid_file()) != NULL) && (*pid_file != '\0')) {
00584                 char pidbuf[16];
00585                 int fd;
00586                 int pid = (int) getpid();
00587                 cleanup_set_pid(pid);
00588                 if ((fd = do_open(lp_pid_file(), O_WRONLY|O_CREAT|O_TRUNC,
00589                                         0666 & ~orig_umask)) == -1) {
00590                     cleanup_set_pid(0);
00591                     rsyserr(FLOG, errno, "failed to create pid file %s", pid_file);
00592                     exit_cleanup(RERR_FILEIO);
00593                 }
00594                 snprintf(pidbuf, sizeof(pidbuf), "%d\n", pid);
00595                 write(fd, pidbuf, strlen(pidbuf));
00596                 close(fd);
00597         }
00598 
00599         start_accept_loop(rsync_port, start_daemon);
00600         return -1;
00601 }
00602 

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