nscd/nscd.c

   1 /* Copyright (c) 1998-2006, 2007 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Thorsten Kukuk <kukuk@suse.de>, 1998.
   4
   5    This program is free software; you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License version 2 as
   7    published by the Free Software Foundation.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program; if not, write to the Free Software Foundation,
  16    Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  17
  18 /* nscd - Name Service Cache Daemon. Caches passwd, group, and hosts.  */
  19
  20 #include <argp.h>
  21 #include <assert.h>
  22 #include <dirent.h>
  23 #include <errno.h>
  24 #include <error.h>
  25 #include <fcntl.h>
  26 #include <libintl.h>
  27 #include <locale.h>
  28 #include <paths.h>
  29 #include <pthread.h>
  30 #include <signal.h>
  31 #include <stdbool.h>
  32 #include <stdio.h>
  33 #include <stdlib.h>
  34 #include <string.h>
  35 #include <syslog.h>
  36 #include <unistd.h>
  37 #include <sys/mman.h>
  38 #include <sys/socket.h>
  39 #include <sys/stat.h>
  40 #include <sys/uio.h>
  41 #include <sys/un.h>
  42
  43 #include "dbg_log.h"
  44 #include "nscd.h"
  45 #include "selinux.h"
  46 #include "../nss/nsswitch.h"
  47 #include <device-nrs.h>
  48
  49 /* Get libc version number.  */
  50 #include <version.h>
  51
  52 #define PACKAGE _libc_intl_domainname
  53
  54 /* Structure used by main() thread to keep track of the number of
  55    active threads.  Used to limit how many threads it will create
  56    and under a shutdown condition to wait till all in-progress
  57    requests have finished before "turning off the lights".  */
  58
  59 typedef struct
  60 {
  61   int             num_active;
  62   pthread_cond_t  thread_exit_cv;
  63   pthread_mutex_t mutex;
  64 } thread_info_t;
  65
  66 thread_info_t thread_info;
  67
  68 int do_shutdown;
  69 int disabled_passwd;
  70 int disabled_group;
  71 int go_background = 1;
  72
  73 static const char *conffile = _PATH_NSCDCONF;
  74
  75 time_t start_time;
  76
  77 uintptr_t pagesize_m1;
  78
  79 int paranoia;
  80 time_t restart_time;
  81 time_t restart_interval = RESTART_INTERVAL;
  82 const char *oldcwd;
  83 uid_t old_uid;
  84 gid_t old_gid;
  85
  86 static int check_pid (const char *file);
  87 static int write_pid (const char *file);
  88
  89 /* Name and version of program.  */
  90 static void print_version (FILE *stream, struct argp_state *state);
  91 void (*argp_program_version_hook) (FILE *, struct argp_state *) = print_version;
  92
  93 /* Definitions of arguments for argp functions.  */
  94 static const struct argp_option options[] =
  95 {
  96   { "config-file", 'f', N_("NAME"), 0,
  97     N_("Read configuration data from NAME") },
  98   { "debug", 'd', NULL, 0,
  99     N_("Do not fork and display messages on the current tty") },
 100   { "nthreads", 't', N_("NUMBER"), 0, N_("Start NUMBER threads") },
 101   { "shutdown", 'K', NULL, 0, N_("Shut the server down") },
 102   { "statistic", 'g', NULL, 0, N_("Print current configuration statistic") },
 103   { "invalidate", 'i', N_("TABLE"), 0,
 104     N_("Invalidate the specified cache") },
 105   { "secure", 'S', N_("TABLE,yes"), OPTION_HIDDEN,
 106     N_("Use separate cache for each user")},
 107   { NULL, 0, NULL, 0, NULL }
 108 };
 109
 110 /* Short description of program.  */
 111 static const char doc[] = N_("Name Service Cache Daemon.");
 112
 113 /* Prototype for option handler.  */
 114 static error_t parse_opt (int key, char *arg, struct argp_state *state);
 115
 116 /* Data structure to communicate with argp functions.  */
 117 static struct argp argp =
 118 {
 119   options, parse_opt, NULL, doc,
 120 };
 121
 122 /* The SIGHUP handler is extern to this file */
 123 extern void sighup_handler(int signum);
 124
 125 /* True if only statistics are requested.  */
 126 static bool get_stats;
 127
 128 int
 129 main (int argc, char **argv)
 130 {
 131   int remaining;
 132
 133   /* Set locale via LC_ALL.  */
 134   setlocale (LC_ALL, "");
 135   /* Set the text message domain.  */
 136   textdomain (PACKAGE);
 137
 138   /* Determine if the kernel has SELinux support.  */
 139   nscd_selinux_enabled (&selinux_enabled);
 140
 141   /* Parse and process arguments.  */
 142   argp_parse (&argp, argc, argv, 0, &remaining, NULL);
 143
 144   if (remaining != argc)
 145     {
 146       error (0, 0, gettext ("wrong number of arguments"));
 147       argp_help (&argp, stdout, ARGP_HELP_SEE, program_invocation_short_name);
 148       exit (1);
 149     }
 150
 151   /* Read the configuration file.  */
 152   if (nscd_parse_file (conffile, dbs) != 0)
 153     /* We couldn't read the configuration file.  We don't start the
 154        server.  */
 155     error (EXIT_FAILURE, 0,
 156            _("failure while reading configuration file; this is fatal"));
 157
 158   /* Do we only get statistics?  */
 159   if (get_stats)
 160     /* Does not return.  */
 161     receive_print_stats ();
 162
 163   /* Check if we are already running. */
 164   if (check_pid (_PATH_NSCDPID))
 165     error (EXIT_FAILURE, 0, _("already running"));
 166
 167   /* Remember when we started.  */
 168   start_time = time (NULL);
 169
 170   /* Determine page size.  */
 171   pagesize_m1 = getpagesize () - 1;
 172
 173   /* Behave like a daemon.  */
 174   if (go_background)
 175     {
 176       int i;
 177
 178       pid_t pid = fork ();
 179       if (pid == -1)
 180         error (EXIT_FAILURE, errno, _("cannot fork"));
 181       if (pid != 0)
 182         exit (0);
 183
 184       int nullfd = open (_PATH_DEVNULL, O_RDWR);
 185       if (nullfd != -1)
 186         {
 187           struct stat64 st;
 188
 189           if (fstat64 (nullfd, &st) == 0 && S_ISCHR (st.st_mode) != 0
 190 #if defined DEV_NULL_MAJOR && defined DEV_NULL_MINOR
 191               && st.st_rdev == makedev (DEV_NULL_MAJOR, DEV_NULL_MINOR)
 192 #endif
 193               )
 194             {
 195               /* It is the /dev/null special device alright.  */
 196               (void) dup2 (nullfd, STDIN_FILENO);
 197               (void) dup2 (nullfd, STDOUT_FILENO);
 198               (void) dup2 (nullfd, STDERR_FILENO);
 199
 200               if (nullfd > 2)
 201                 close (nullfd);
 202             }
 203           else
 204             {
 205               /* Ugh, somebody is trying to play a trick on us.  */
 206               close (nullfd);
 207               nullfd = -1;
 208             }
 209         }
 210       int min_close_fd = nullfd == -1 ? 0 : STDERR_FILENO + 1;
 211
 212       DIR *d = opendir ("/proc/self/fd");
 213       if (d != NULL)
 214         {
 215           struct dirent64 *dirent;
 216           int dfdn = dirfd (d);
 217
 218           while ((dirent = readdir64 (d)) != NULL)
 219             {
 220               char *endp;
 221               long int fdn = strtol (dirent->d_name, &endp, 10);
 222
 223               if (*endp == '\0' && fdn != dfdn && fdn >= min_close_fd)
 224                 close ((int) fdn);
 225             }
 226
 227           closedir (d);
 228         }
 229       else
 230         for (i = min_close_fd; i < getdtablesize (); i++)
 231           close (i);
 232
 233       pid = fork ();
 234       if (pid == -1)
 235         error (EXIT_FAILURE, errno, _("cannot fork"));
 236       if (pid != 0)
 237         exit (0);
 238
 239       setsid ();
 240
 241       if (chdir ("/") != 0)
 242         error (EXIT_FAILURE, errno,
 243                _("cannot change current working directory to \"/\""));
 244
 245       openlog ("nscd", LOG_CONS | LOG_ODELAY, LOG_DAEMON);
 246
 247       if (write_pid (_PATH_NSCDPID) < 0)
 248         dbg_log ("%s: %s", _PATH_NSCDPID, strerror (errno));
 249
 250       if (!init_logfile ())
 251         dbg_log (_("Could not create log file"));
 252
 253       /* Ignore job control signals.  */
 254       signal (SIGTTOU, SIG_IGN);
 255       signal (SIGTTIN, SIG_IGN);
 256       signal (SIGTSTP, SIG_IGN);
 257     }
 258   else
 259     /* In foreground mode we are not paranoid.  */
 260     paranoia = 0;
 261
 262   /* Start the SELinux AVC.  */
 263   if (selinux_enabled)
 264     nscd_avc_init ();
 265
 266   signal (SIGINT, termination_handler);
 267   signal (SIGQUIT, termination_handler);
 268   signal (SIGTERM, termination_handler);
 269   signal (SIGHUP, sighup_handler);
 270   signal (SIGPIPE, SIG_IGN);
 271
 272   /* Cleanup files created by a previous 'bind'.  */
 273   unlink (_PATH_NSCDSOCKET);
 274
 275   /* Make sure we do not get recursive calls.  */
 276   __nss_disable_nscd ();
 277
 278   /* Init databases.  */
 279   nscd_init ();
 280
 281   /* Handle incoming requests */
 282   start_threads ();
 283
 284   return 0;
 285 }
 286
 287
 288 /* Handle program arguments.  */
 289 static error_t
 290 parse_opt (int key, char *arg, struct argp_state *state)
 291 {
 292   switch (key)
 293     {
 294     case 'd':
 295       ++debug_level;
 296       go_background = 0;
 297       break;
 298
 299     case 'f':
 300       conffile = arg;
 301       break;
 302
 303     case 'K':
 304       if (getuid () != 0)
 305         error (4, 0, _("Only root is allowed to use this option!"));
 306       {
 307         int sock = nscd_open_socket ();
 308
 309         if (sock == -1)
 310           exit (EXIT_FAILURE);
 311
 312         request_header req;
 313         req.version = NSCD_VERSION;
 314         req.type = SHUTDOWN;
 315         req.key_len = 0;
 316
 317         ssize_t nbytes = TEMP_FAILURE_RETRY (send (sock, &req,
 318                                                    sizeof (request_header),
 319                                                    MSG_NOSIGNAL));
 320         close (sock);
 321         exit (nbytes != sizeof (request_header) ? EXIT_FAILURE : EXIT_SUCCESS);
 322       }
 323
 324     case 'g':
 325       get_stats = true;
 326       break;
 327
 328     case 'i':
 329       if (getuid () != 0)
 330         error (4, 0, _("Only root is allowed to use this option!"));
 331       else
 332         {
 333           int sock = nscd_open_socket ();
 334
 335           if (sock == -1)
 336             exit (EXIT_FAILURE);
 337
 338           dbtype cnt;
 339           for (cnt = pwddb; cnt < lastdb; ++cnt)
 340             if (strcmp (arg, dbnames[cnt]) == 0)
 341               break;
 342
 343           if (cnt == lastdb)
 344             return ARGP_ERR_UNKNOWN;
 345
 346           size_t arg_len = strlen (arg) + 1;
 347           struct
 348           {
 349             request_header req;
 350             char arg[arg_len];
 351           } reqdata;
 352
 353           reqdata.req.key_len = strlen (arg) + 1;
 354           reqdata.req.version = NSCD_VERSION;
 355           reqdata.req.type = INVALIDATE;
 356           memcpy (reqdata.arg, arg, arg_len);
 357
 358           ssize_t nbytes = TEMP_FAILURE_RETRY (send (sock, &reqdata,
 359                                                      sizeof (request_header)
 360                                                      + arg_len,
 361                                                      MSG_NOSIGNAL));
 362
 363           if (nbytes != sizeof (request_header) + arg_len)
 364             {
 365               int err = errno;
 366               close (sock);
 367               error (EXIT_FAILURE, err, _("write incomplete"));
 368             }
 369
 370           /* Wait for ack.  Older nscd just closed the socket when
 371              prune_cache finished, silently ignore that.  */
 372           int32_t resp = 0;
 373           nbytes = TEMP_FAILURE_RETRY (read (sock, &resp, sizeof (resp)));
 374           if (nbytes != 0 && nbytes != sizeof (resp))
 375             {
 376               int err = errno;
 377               close (sock);
 378               error (EXIT_FAILURE, err, _("cannot read invalidate ACK"));
 379             }
 380
 381           close (sock);
 382
 383           if (resp != 0)
 384             error (EXIT_FAILURE, resp, _("invalidation failed"));
 385
 386           exit (0);
 387         }
 388
 389     case 't':
 390       nthreads = atol (arg);
 391       break;
 392
 393     case 'S':
 394       error (0, 0, _("secure services not implemented anymore"));
 395       break;
 396
 397     default:
 398       return ARGP_ERR_UNKNOWN;
 399     }
 400
 401   return 0;
 402 }
 403
 404 /* Print the version information.  */
 405 static void
 406 print_version (FILE *stream, struct argp_state *state)
 407 {
 408   fprintf (stream, "nscd (GNU %s) %s\n", PACKAGE, VERSION);
 409   fprintf (stream, gettext ("\
 410 Copyright (C) %s Free Software Foundation, Inc.\n\
 411 This is free software; see the source for copying conditions.  There is NO\n\
 412 warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.\n\
 413 "), "2007");
 414   fprintf (stream, gettext ("Written by %s.\n"),
 415            "Thorsten Kukuk and Ulrich Drepper");
 416 }
 417
 418
 419 /* Create a socket connected to a name.  */
 420 int
 421 nscd_open_socket (void)
 422 {
 423   struct sockaddr_un addr;
 424   int sock;
 425
 426   sock = socket (PF_UNIX, SOCK_STREAM, 0);
 427   if (sock < 0)
 428     return -1;
 429
 430   addr.sun_family = AF_UNIX;
 431   assert (sizeof (addr.sun_path) >= sizeof (_PATH_NSCDSOCKET));
 432   strcpy (addr.sun_path, _PATH_NSCDSOCKET);
 433   if (connect (sock, (struct sockaddr *) &addr, sizeof (addr)) < 0)
 434     {
 435       close (sock);
 436       return -1;
 437     }
 438
 439   return sock;
 440 }
 441
 442
 443 /* Cleanup.  */
 444 void
 445 termination_handler (int signum)
 446 {
 447   close_sockets ();
 448
 449   /* Clean up the file created by 'bind'.  */
 450   unlink (_PATH_NSCDSOCKET);
 451
 452   /* Clean up pid file.  */
 453   unlink (_PATH_NSCDPID);
 454
 455   // XXX Terminate threads.
 456
 457   /* Synchronize memory.  */
 458   for (int cnt = 0; cnt < lastdb; ++cnt)
 459     {
 460       if (!dbs[cnt].enabled)
 461         continue;
 462
 463       /* Make sure nobody keeps using the database.  */
 464       dbs[cnt].head->timestamp = 0;
 465
 466       if (dbs[cnt].persistent)
 467         // XXX async OK?
 468         msync (dbs[cnt].head, dbs[cnt].memsize, MS_ASYNC);
 469     }
 470
 471   /* Shutdown the SELinux AVC.  */
 472   if (selinux_enabled)
 473     nscd_avc_destroy ();
 474
 475   _exit (EXIT_SUCCESS);
 476 }
 477
 478 /* Returns 1 if the process in pid file FILE is running, 0 if not.  */
 479 static int
 480 check_pid (const char *file)
 481 {
 482   FILE *fp;
 483
 484   fp = fopen (file, "r");
 485   if (fp)
 486     {
 487       pid_t pid;
 488       int n;
 489
 490       n = fscanf (fp, "%d", &pid);
 491       fclose (fp);
 492
 493       /* If we cannot parse the file default to assuming nscd runs.
 494          If the PID is alive, assume it is running.  That all unless
 495          the PID is the same as the current process' since tha latter
 496          can mean we re-exec.  */
 497       if ((n != 1 || kill (pid, 0) == 0) && pid != getpid ())
 498         return 1;
 499     }
 500
 501   return 0;
 502 }
 503
 504 /* Write the current process id to the file FILE.
 505    Returns 0 if successful, -1 if not.  */
 506 static int
 507 write_pid (const char *file)
 508 {
 509   FILE *fp;
 510
 511   fp = fopen (file, "w");
 512   if (fp == NULL)
 513     return -1;
 514
 515   fprintf (fp, "%d\n", getpid ());
 516
 517   int result = fflush (fp) || ferror (fp) ? -1 : 0;
 518
 519   fclose (fp);
 520
 521   return result;
 522 }