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 /* True if only statistics are requested.  */
 123 static bool get_stats;
 124
 125 int
 126 main (int argc, char **argv)
 127 {
 128   int remaining;
 129
 130   /* Set locale via LC_ALL.  */
 131   setlocale (LC_ALL, "");
 132   /* Set the text message domain.  */
 133   textdomain (PACKAGE);
 134
 135   /* Determine if the kernel has SELinux support.  */
 136   nscd_selinux_enabled (&selinux_enabled);
 137
 138   /* Parse and process arguments.  */
 139   argp_parse (&argp, argc, argv, 0, &remaining, NULL);
 140
 141   if (remaining != argc)
 142     {
 143       error (0, 0, gettext ("wrong number of arguments"));
 144       argp_help (&argp, stdout, ARGP_HELP_SEE, program_invocation_short_name);
 145       exit (1);
 146     }
 147
 148   /* Read the configuration file.  */
 149   if (nscd_parse_file (conffile, dbs) != 0)
 150     /* We couldn't read the configuration file.  We don't start the
 151        server.  */
 152     error (EXIT_FAILURE, 0,
 153            _("failure while reading configuration file; this is fatal"));
 154
 155   /* Do we only get statistics?  */
 156   if (get_stats)
 157     /* Does not return.  */
 158     receive_print_stats ();
 159
 160   /* Check if we are already running. */
 161   if (check_pid (_PATH_NSCDPID))
 162     error (EXIT_FAILURE, 0, _("already running"));
 163
 164   /* Remember when we started.  */
 165   start_time = time (NULL);
 166
 167   /* Determine page size.  */
 168   pagesize_m1 = getpagesize () - 1;
 169
 170   /* Behave like a daemon.  */
 171   if (go_background)
 172     {
 173       int i;
 174
 175       pid_t pid = fork ();
 176       if (pid == -1)
 177         error (EXIT_FAILURE, errno, _("cannot fork"));
 178       if (pid != 0)
 179         exit (0);
 180
 181       int nullfd = open (_PATH_DEVNULL, O_RDWR);
 182       if (nullfd != -1)
 183         {
 184           struct stat64 st;
 185
 186           if (fstat64 (nullfd, &st) == 0 && S_ISCHR (st.st_mode) != 0
 187 #if defined DEV_NULL_MAJOR && defined DEV_NULL_MINOR
 188               && st.st_rdev == makedev (DEV_NULL_MAJOR, DEV_NULL_MINOR)
 189 #endif
 190               )
 191             {
 192               /* It is the /dev/null special device alright.  */
 193               (void) dup2 (nullfd, STDIN_FILENO);
 194               (void) dup2 (nullfd, STDOUT_FILENO);
 195               (void) dup2 (nullfd, STDERR_FILENO);
 196
 197               if (nullfd > 2)
 198                 close (nullfd);
 199             }
 200           else
 201             {
 202               /* Ugh, somebody is trying to play a trick on us.  */
 203               close (nullfd);
 204               nullfd = -1;
 205             }
 206         }
 207       int min_close_fd = nullfd == -1 ? 0 : STDERR_FILENO + 1;
 208
 209       DIR *d = opendir ("/proc/self/fd");
 210       if (d != NULL)
 211         {
 212           struct dirent64 *dirent;
 213           int dfdn = dirfd (d);
 214
 215           while ((dirent = readdir64 (d)) != NULL)
 216             {
 217               char *endp;
 218               long int fdn = strtol (dirent->d_name, &endp, 10);
 219
 220               if (*endp == '\0' && fdn != dfdn && fdn >= min_close_fd)
 221                 close ((int) fdn);
 222             }
 223
 224           closedir (d);
 225         }
 226       else
 227         for (i = min_close_fd; i < getdtablesize (); i++)
 228           close (i);
 229
 230       pid = fork ();
 231       if (pid == -1)
 232         error (EXIT_FAILURE, errno, _("cannot fork"));
 233       if (pid != 0)
 234         exit (0);
 235
 236       setsid ();
 237
 238       if (chdir ("/") != 0)
 239         error (EXIT_FAILURE, errno,
 240                _("cannot change current working directory to \"/\""));
 241
 242       openlog ("nscd", LOG_CONS | LOG_ODELAY, LOG_DAEMON);
 243
 244       if (write_pid (_PATH_NSCDPID) < 0)
 245         dbg_log ("%s: %s", _PATH_NSCDPID, strerror (errno));
 246
 247       if (!init_logfile ())
 248         dbg_log (_("Could not create log file"));
 249
 250       /* Ignore job control signals.  */
 251       signal (SIGTTOU, SIG_IGN);
 252       signal (SIGTTIN, SIG_IGN);
 253       signal (SIGTSTP, SIG_IGN);
 254     }
 255   else
 256     /* In foreground mode we are not paranoid.  */
 257     paranoia = 0;
 258
 259   /* Start the SELinux AVC.  */
 260   if (selinux_enabled)
 261     nscd_avc_init ();
 262
 263   signal (SIGINT, termination_handler);
 264   signal (SIGQUIT, termination_handler);
 265   signal (SIGTERM, termination_handler);
 266   signal (SIGPIPE, SIG_IGN);
 267
 268   /* Cleanup files created by a previous 'bind'.  */
 269   unlink (_PATH_NSCDSOCKET);
 270
 271   /* Make sure we do not get recursive calls.  */
 272   __nss_disable_nscd ();
 273
 274   /* Init databases.  */
 275   nscd_init ();
 276
 277   /* Handle incoming requests */
 278   start_threads ();
 279
 280   return 0;
 281 }
 282
 283
 284 /* Handle program arguments.  */
 285 static error_t
 286 parse_opt (int key, char *arg, struct argp_state *state)
 287 {
 288   switch (key)
 289     {
 290     case 'd':
 291       ++debug_level;
 292       go_background = 0;
 293       break;
 294
 295     case 'f':
 296       conffile = arg;
 297       break;
 298
 299     case 'K':
 300       if (getuid () != 0)
 301         error (4, 0, _("Only root is allowed to use this option!"));
 302       {
 303         int sock = nscd_open_socket ();
 304
 305         if (sock == -1)
 306           exit (EXIT_FAILURE);
 307
 308         request_header req;
 309         req.version = NSCD_VERSION;
 310         req.type = SHUTDOWN;
 311         req.key_len = 0;
 312
 313         ssize_t nbytes = TEMP_FAILURE_RETRY (send (sock, &req,
 314                                                    sizeof (request_header),
 315                                                    MSG_NOSIGNAL));
 316         close (sock);
 317         exit (nbytes != sizeof (request_header) ? EXIT_FAILURE : EXIT_SUCCESS);
 318       }
 319
 320     case 'g':
 321       get_stats = true;
 322       break;
 323
 324     case 'i':
 325       if (getuid () != 0)
 326         error (4, 0, _("Only root is allowed to use this option!"));
 327       else
 328         {
 329           int sock = nscd_open_socket ();
 330
 331           if (sock == -1)
 332             exit (EXIT_FAILURE);
 333
 334           dbtype cnt;
 335           for (cnt = pwddb; cnt < lastdb; ++cnt)
 336             if (strcmp (arg, dbnames[cnt]) == 0)
 337               break;
 338
 339           if (cnt == lastdb)
 340             return ARGP_ERR_UNKNOWN;
 341
 342           size_t arg_len = strlen (arg) + 1;
 343           struct
 344           {
 345             request_header req;
 346             char arg[arg_len];
 347           } reqdata;
 348
 349           reqdata.req.key_len = strlen (arg) + 1;
 350           reqdata.req.version = NSCD_VERSION;
 351           reqdata.req.type = INVALIDATE;
 352           memcpy (reqdata.arg, arg, arg_len);
 353
 354           ssize_t nbytes = TEMP_FAILURE_RETRY (send (sock, &reqdata,
 355                                                      sizeof (request_header)
 356                                                      + arg_len,
 357                                                      MSG_NOSIGNAL));
 358
 359           if (nbytes != sizeof (request_header) + arg_len)
 360             {
 361               int err = errno;
 362               close (sock);
 363               error (EXIT_FAILURE, err, _("write incomplete"));
 364             }
 365
 366           /* Wait for ack.  Older nscd just closed the socket when
 367              prune_cache finished, silently ignore that.  */
 368           int32_t resp = 0;
 369           nbytes = TEMP_FAILURE_RETRY (read (sock, &resp, sizeof (resp)));
 370           if (nbytes != 0 && nbytes != sizeof (resp))
 371             {
 372               int err = errno;
 373               close (sock);
 374               error (EXIT_FAILURE, err, _("cannot read invalidate ACK"));
 375             }
 376
 377           close (sock);
 378
 379           if (resp != 0)
 380             error (EXIT_FAILURE, resp, _("invalidation failed"));
 381
 382           exit (0);
 383         }
 384
 385     case 't':
 386       nthreads = atol (arg);
 387       break;
 388
 389     case 'S':
 390       error (0, 0, _("secure services not implemented anymore"));
 391       break;
 392
 393     default:
 394       return ARGP_ERR_UNKNOWN;
 395     }
 396
 397   return 0;
 398 }
 399
 400 /* Print the version information.  */
 401 static void
 402 print_version (FILE *stream, struct argp_state *state)
 403 {
 404   fprintf (stream, "nscd (GNU %s) %s\n", PACKAGE, VERSION);
 405   fprintf (stream, gettext ("\
 406 Copyright (C) %s Free Software Foundation, Inc.\n\
 407 This is free software; see the source for copying conditions.  There is NO\n\
 408 warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.\n\
 409 "), "2007");
 410   fprintf (stream, gettext ("Written by %s.\n"),
 411            "Thorsten Kukuk and Ulrich Drepper");
 412 }
 413
 414
 415 /* Create a socket connected to a name.  */
 416 int
 417 nscd_open_socket (void)
 418 {
 419   struct sockaddr_un addr;
 420   int sock;
 421
 422   sock = socket (PF_UNIX, SOCK_STREAM, 0);
 423   if (sock < 0)
 424     return -1;
 425
 426   addr.sun_family = AF_UNIX;
 427   assert (sizeof (addr.sun_path) >= sizeof (_PATH_NSCDSOCKET));
 428   strcpy (addr.sun_path, _PATH_NSCDSOCKET);
 429   if (connect (sock, (struct sockaddr *) &addr, sizeof (addr)) < 0)
 430     {
 431       close (sock);
 432       return -1;
 433     }
 434
 435   return sock;
 436 }
 437
 438
 439 /* Cleanup.  */
 440 void
 441 termination_handler (int signum)
 442 {
 443   close_sockets ();
 444
 445   /* Clean up the file created by 'bind'.  */
 446   unlink (_PATH_NSCDSOCKET);
 447
 448   /* Clean up pid file.  */
 449   unlink (_PATH_NSCDPID);
 450
 451   // XXX Terminate threads.
 452
 453   /* Synchronize memory.  */
 454   for (int cnt = 0; cnt < lastdb; ++cnt)
 455     {
 456       if (!dbs[cnt].enabled)
 457         continue;
 458
 459       /* Make sure nobody keeps using the database.  */
 460       dbs[cnt].head->timestamp = 0;
 461
 462       if (dbs[cnt].persistent)
 463         // XXX async OK?
 464         msync (dbs[cnt].head, dbs[cnt].memsize, MS_ASYNC);
 465     }
 466
 467   /* Shutdown the SELinux AVC.  */
 468   if (selinux_enabled)
 469     nscd_avc_destroy ();
 470
 471   _exit (EXIT_SUCCESS);
 472 }
 473
 474 /* Returns 1 if the process in pid file FILE is running, 0 if not.  */
 475 static int
 476 check_pid (const char *file)
 477 {
 478   FILE *fp;
 479
 480   fp = fopen (file, "r");
 481   if (fp)
 482     {
 483       pid_t pid;
 484       int n;
 485
 486       n = fscanf (fp, "%d", &pid);
 487       fclose (fp);
 488
 489       /* If we cannot parse the file default to assuming nscd runs.
 490          If the PID is alive, assume it is running.  That all unless
 491          the PID is the same as the current process' since tha latter
 492          can mean we re-exec.  */
 493       if ((n != 1 || kill (pid, 0) == 0) && pid != getpid ())
 494         return 1;
 495     }
 496
 497   return 0;
 498 }
 499
 500 /* Write the current process id to the file FILE.
 501    Returns 0 if successful, -1 if not.  */
 502 static int
 503 write_pid (const char *file)
 504 {
 505   FILE *fp;
 506
 507   fp = fopen (file, "w");
 508   if (fp == NULL)
 509     return -1;
 510
 511   fprintf (fp, "%d\n", getpid ());
 512
 513   int result = fflush (fp) || ferror (fp) ? -1 : 0;
 514
 515   fclose (fp);
 516
 517   return result;
 518 }