nscd/nscd.c

   1 /* Copyright (c) 1998-2006, 2007, 2008 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 as published
   7    by the Free Software Foundation; version 2 of the License, or
   8    (at your option) any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program; if not, write to the Free Software Foundation,
  17    Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  18
  19 /* nscd - Name Service Cache Daemon. Caches passwd, group, and hosts.  */
  20
  21 #include <argp.h>
  22 #include <assert.h>
  23 #include <dirent.h>
  24 #include <errno.h>
  25 #include <error.h>
  26 #include <fcntl.h>
  27 #include <libintl.h>
  28 #include <locale.h>
  29 #include <paths.h>
  30 #include <pthread.h>
  31 #include <signal.h>
  32 #include <stdbool.h>
  33 #include <stdio.h>
  34 #include <stdlib.h>
  35 #include <string.h>
  36 #include <syslog.h>
  37 #include <unistd.h>
  38 #include <sys/mman.h>
  39 #include <sys/socket.h>
  40 #include <sys/stat.h>
  41 #include <sys/uio.h>
  42 #include <sys/un.h>
  43
  44 #include "dbg_log.h"
  45 #include "nscd.h"
  46 #include "selinux.h"
  47 #include "../nss/nsswitch.h"
  48 #include <device-nrs.h>
  49
  50 /* Get libc version number.  */
  51 #include <version.h>
  52
  53 #define PACKAGE _libc_intl_domainname
  54
  55 /* Structure used by main() thread to keep track of the number of
  56    active threads.  Used to limit how many threads it will create
  57    and under a shutdown condition to wait till all in-progress
  58    requests have finished before "turning off the lights".  */
  59
  60 typedef struct
  61 {
  62   int             num_active;
  63   pthread_cond_t  thread_exit_cv;
  64   pthread_mutex_t mutex;
  65 } thread_info_t;
  66
  67 thread_info_t thread_info;
  68
  69 int do_shutdown;
  70 int disabled_passwd;
  71 int disabled_group;
  72 int go_background = 1;
  73
  74 static const char *conffile = _PATH_NSCDCONF;
  75
  76 time_t start_time;
  77
  78 uintptr_t pagesize_m1;
  79
  80 int paranoia;
  81 time_t restart_time;
  82 time_t restart_interval = RESTART_INTERVAL;
  83 const char *oldcwd;
  84 uid_t old_uid;
  85 gid_t old_gid;
  86
  87 static int check_pid (const char *file);
  88 static int write_pid (const char *file);
  89
  90 /* Name and version of program.  */
  91 static void print_version (FILE *stream, struct argp_state *state);
  92 void (*argp_program_version_hook) (FILE *, struct argp_state *) = print_version;
  93
  94 /* Definitions of arguments for argp functions.  */
  95 static const struct argp_option options[] =
  96 {
  97   { "config-file", 'f', N_("NAME"), 0,
  98     N_("Read configuration data from NAME") },
  99   { "debug", 'd', NULL, 0,
 100     N_("Do not fork and display messages on the current tty") },
 101   { "nthreads", 't', N_("NUMBER"), 0, N_("Start NUMBER threads") },
 102   { "shutdown", 'K', NULL, 0, N_("Shut the server down") },
 103   { "statistic", 'g', NULL, 0, N_("Print current configuration statistic") },
 104   { "invalidate", 'i', N_("TABLE"), 0,
 105     N_("Invalidate the specified cache") },
 106   { "secure", 'S', N_("TABLE,yes"), OPTION_HIDDEN,
 107     N_("Use separate cache for each user")},
 108   { NULL, 0, NULL, 0, NULL }
 109 };
 110
 111 /* Short description of program.  */
 112 static const char doc[] = N_("Name Service Cache Daemon.");
 113
 114 /* Prototype for option handler.  */
 115 static error_t parse_opt (int key, char *arg, struct argp_state *state);
 116
 117 /* Data structure to communicate with argp functions.  */
 118 static struct argp argp =
 119 {
 120   options, parse_opt, NULL, doc,
 121 };
 122
 123 /* True if only statistics are requested.  */
 124 static bool get_stats;
 125
 126 int
 127 main (int argc, char **argv)
 128 {
 129   int remaining;
 130
 131   /* Set locale via LC_ALL.  */
 132   setlocale (LC_ALL, "");
 133   /* Set the text message domain.  */
 134   textdomain (PACKAGE);
 135
 136   /* Determine if the kernel has SELinux support.  */
 137   nscd_selinux_enabled (&selinux_enabled);
 138
 139   /* Parse and process arguments.  */
 140   argp_parse (&argp, argc, argv, 0, &remaining, NULL);
 141
 142   if (remaining != argc)
 143     {
 144       error (0, 0, gettext ("wrong number of arguments"));
 145       argp_help (&argp, stdout, ARGP_HELP_SEE, program_invocation_short_name);
 146       exit (1);
 147     }
 148
 149   /* Read the configuration file.  */
 150   if (nscd_parse_file (conffile, dbs) != 0)
 151     /* We couldn't read the configuration file.  We don't start the
 152        server.  */
 153     error (EXIT_FAILURE, 0,
 154            _("failure while reading configuration file; this is fatal"));
 155
 156   /* Do we only get statistics?  */
 157   if (get_stats)
 158     /* Does not return.  */
 159     receive_print_stats ();
 160
 161   /* Check if we are already running. */
 162   if (check_pid (_PATH_NSCDPID))
 163     error (EXIT_FAILURE, 0, _("already running"));
 164
 165   /* Remember when we started.  */
 166   start_time = time (NULL);
 167
 168   /* Determine page size.  */
 169   pagesize_m1 = getpagesize () - 1;
 170
 171   /* Behave like a daemon.  */
 172   if (go_background)
 173     {
 174       int i;
 175
 176       pid_t pid = fork ();
 177       if (pid == -1)
 178         error (EXIT_FAILURE, errno, _("cannot fork"));
 179       if (pid != 0)
 180         exit (0);
 181
 182       int nullfd = open (_PATH_DEVNULL, O_RDWR);
 183       if (nullfd != -1)
 184         {
 185           struct stat64 st;
 186
 187           if (fstat64 (nullfd, &st) == 0 && S_ISCHR (st.st_mode) != 0
 188 #if defined DEV_NULL_MAJOR && defined DEV_NULL_MINOR
 189               && st.st_rdev == makedev (DEV_NULL_MAJOR, DEV_NULL_MINOR)
 190 #endif
 191               )
 192             {
 193               /* It is the /dev/null special device alright.  */
 194               (void) dup2 (nullfd, STDIN_FILENO);
 195               (void) dup2 (nullfd, STDOUT_FILENO);
 196               (void) dup2 (nullfd, STDERR_FILENO);
 197
 198               if (nullfd > 2)
 199                 close (nullfd);
 200             }
 201           else
 202             {
 203               /* Ugh, somebody is trying to play a trick on us.  */
 204               close (nullfd);
 205               nullfd = -1;
 206             }
 207         }
 208       int min_close_fd = nullfd == -1 ? 0 : STDERR_FILENO + 1;
 209
 210       DIR *d = opendir ("/proc/self/fd");
 211       if (d != NULL)
 212         {
 213           struct dirent64 *dirent;
 214           int dfdn = dirfd (d);
 215
 216           while ((dirent = readdir64 (d)) != NULL)
 217             {
 218               char *endp;
 219               long int fdn = strtol (dirent->d_name, &endp, 10);
 220
 221               if (*endp == '\0' && fdn != dfdn && fdn >= min_close_fd)
 222                 close ((int) fdn);
 223             }
 224
 225           closedir (d);
 226         }
 227       else
 228         for (i = min_close_fd; i < getdtablesize (); i++)
 229           close (i);
 230
 231       pid = fork ();
 232       if (pid == -1)
 233         error (EXIT_FAILURE, errno, _("cannot fork"));
 234       if (pid != 0)
 235         exit (0);
 236
 237       setsid ();
 238
 239       if (chdir ("/") != 0)
 240         error (EXIT_FAILURE, errno,
 241                _("cannot change current working directory to \"/\""));
 242
 243       openlog ("nscd", LOG_CONS | LOG_ODELAY, LOG_DAEMON);
 244
 245       if (write_pid (_PATH_NSCDPID) < 0)
 246         dbg_log ("%s: %s", _PATH_NSCDPID, strerror (errno));
 247
 248       if (!init_logfile ())
 249         dbg_log (_("Could not create log file"));
 250
 251       /* Ignore job control signals.  */
 252       signal (SIGTTOU, SIG_IGN);
 253       signal (SIGTTIN, SIG_IGN);
 254       signal (SIGTSTP, SIG_IGN);
 255     }
 256   else
 257     /* In foreground mode we are not paranoid.  */
 258     paranoia = 0;
 259
 260   /* Start the SELinux AVC.  */
 261   if (selinux_enabled)
 262     nscd_avc_init ();
 263
 264   signal (SIGINT, termination_handler);
 265   signal (SIGQUIT, termination_handler);
 266   signal (SIGTERM, termination_handler);
 267   signal (SIGPIPE, SIG_IGN);
 268
 269   /* Cleanup files created by a previous 'bind'.  */
 270   unlink (_PATH_NSCDSOCKET);
 271
 272   /* Make sure we do not get recursive calls.  */
 273   __nss_disable_nscd ();
 274
 275   /* Init databases.  */
 276   nscd_init ();
 277
 278   /* Handle incoming requests */
 279   start_threads ();
 280
 281   return 0;
 282 }
 283
 284
 285 /* Handle program arguments.  */
 286 static error_t
 287 parse_opt (int key, char *arg, struct argp_state *state)
 288 {
 289   switch (key)
 290     {
 291     case 'd':
 292       ++debug_level;
 293       go_background = 0;
 294       break;
 295
 296     case 'f':
 297       conffile = arg;
 298       break;
 299
 300     case 'K':
 301       if (getuid () != 0)
 302         error (4, 0, _("Only root is allowed to use this option!"));
 303       {
 304         int sock = nscd_open_socket ();
 305
 306         if (sock == -1)
 307           exit (EXIT_FAILURE);
 308
 309         request_header req;
 310         req.version = NSCD_VERSION;
 311         req.type = SHUTDOWN;
 312         req.key_len = 0;
 313
 314         ssize_t nbytes = TEMP_FAILURE_RETRY (send (sock, &req,
 315                                                    sizeof (request_header),
 316                                                    MSG_NOSIGNAL));
 317         close (sock);
 318         exit (nbytes != sizeof (request_header) ? EXIT_FAILURE : EXIT_SUCCESS);
 319       }
 320
 321     case 'g':
 322       get_stats = true;
 323       break;
 324
 325     case 'i':
 326       if (getuid () != 0)
 327         error (4, 0, _("Only root is allowed to use this option!"));
 328       else
 329         {
 330           int sock = nscd_open_socket ();
 331
 332           if (sock == -1)
 333             exit (EXIT_FAILURE);
 334
 335           dbtype cnt;
 336           for (cnt = pwddb; cnt < lastdb; ++cnt)
 337             if (strcmp (arg, dbnames[cnt]) == 0)
 338               break;
 339
 340           if (cnt == lastdb)
 341             return ARGP_ERR_UNKNOWN;
 342
 343           size_t arg_len = strlen (arg) + 1;
 344           struct
 345           {
 346             request_header req;
 347             char arg[arg_len];
 348           } reqdata;
 349
 350           reqdata.req.key_len = strlen (arg) + 1;
 351           reqdata.req.version = NSCD_VERSION;
 352           reqdata.req.type = INVALIDATE;
 353           memcpy (reqdata.arg, arg, arg_len);
 354
 355           ssize_t nbytes = TEMP_FAILURE_RETRY (send (sock, &reqdata,
 356                                                      sizeof (request_header)
 357                                                      + arg_len,
 358                                                      MSG_NOSIGNAL));
 359
 360           if (nbytes != sizeof (request_header) + arg_len)
 361             {
 362               int err = errno;
 363               close (sock);
 364               error (EXIT_FAILURE, err, _("write incomplete"));
 365             }
 366
 367           /* Wait for ack.  Older nscd just closed the socket when
 368              prune_cache finished, silently ignore that.  */
 369           int32_t resp = 0;
 370           nbytes = TEMP_FAILURE_RETRY (read (sock, &resp, sizeof (resp)));
 371           if (nbytes != 0 && nbytes != sizeof (resp))
 372             {
 373               int err = errno;
 374               close (sock);
 375               error (EXIT_FAILURE, err, _("cannot read invalidate ACK"));
 376             }
 377
 378           close (sock);
 379
 380           if (resp != 0)
 381             error (EXIT_FAILURE, resp, _("invalidation failed"));
 382
 383           exit (0);
 384         }
 385
 386     case 't':
 387       nthreads = atol (arg);
 388       break;
 389
 390     case 'S':
 391       error (0, 0, _("secure services not implemented anymore"));
 392       break;
 393
 394     default:
 395       return ARGP_ERR_UNKNOWN;
 396     }
 397
 398   return 0;
 399 }
 400
 401 /* Print the version information.  */
 402 static void
 403 print_version (FILE *stream, struct argp_state *state)
 404 {
 405   fprintf (stream, "nscd (GNU %s) %s\n", PACKAGE, VERSION);
 406   fprintf (stream, gettext ("\
 407 Copyright (C) %s Free Software Foundation, Inc.\n\
 408 This is free software; see the source for copying conditions.  There is NO\n\
 409 warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.\n\
 410 "), "2008");
 411   fprintf (stream, gettext ("Written by %s.\n"),
 412            "Thorsten Kukuk and Ulrich Drepper");
 413 }
 414
 415
 416 /* Create a socket connected to a name.  */
 417 int
 418 nscd_open_socket (void)
 419 {
 420   struct sockaddr_un addr;
 421   int sock;
 422
 423   sock = socket (PF_UNIX, SOCK_STREAM, 0);
 424   if (sock < 0)
 425     return -1;
 426
 427   addr.sun_family = AF_UNIX;
 428   assert (sizeof (addr.sun_path) >= sizeof (_PATH_NSCDSOCKET));
 429   strcpy (addr.sun_path, _PATH_NSCDSOCKET);
 430   if (connect (sock, (struct sockaddr *) &addr, sizeof (addr)) < 0)
 431     {
 432       close (sock);
 433       return -1;
 434     }
 435
 436   return sock;
 437 }
 438
 439
 440 /* Cleanup.  */
 441 void
 442 termination_handler (int signum)
 443 {
 444   close_sockets ();
 445
 446   /* Clean up the file created by 'bind'.  */
 447   unlink (_PATH_NSCDSOCKET);
 448
 449   /* Clean up pid file.  */
 450   unlink (_PATH_NSCDPID);
 451
 452   // XXX Terminate threads.
 453
 454   /* Synchronize memory.  */
 455   for (int cnt = 0; cnt < lastdb; ++cnt)
 456     {
 457       if (!dbs[cnt].enabled)
 458         continue;
 459
 460       /* Make sure nobody keeps using the database.  */
 461       dbs[cnt].head->timestamp = 0;
 462
 463       if (dbs[cnt].persistent)
 464         // XXX async OK?
 465         msync (dbs[cnt].head, dbs[cnt].memsize, MS_ASYNC);
 466     }
 467
 468   /* Shutdown the SELinux AVC.  */
 469   if (selinux_enabled)
 470     nscd_avc_destroy ();
 471
 472   _exit (EXIT_SUCCESS);
 473 }
 474
 475 /* Returns 1 if the process in pid file FILE is running, 0 if not.  */
 476 static int
 477 check_pid (const char *file)
 478 {
 479   FILE *fp;
 480
 481   fp = fopen (file, "r");
 482   if (fp)
 483     {
 484       pid_t pid;
 485       int n;
 486
 487       n = fscanf (fp, "%d", &pid);
 488       fclose (fp);
 489
 490       /* If we cannot parse the file default to assuming nscd runs.
 491          If the PID is alive, assume it is running.  That all unless
 492          the PID is the same as the current process' since tha latter
 493          can mean we re-exec.  */
 494       if ((n != 1 || kill (pid, 0) == 0) && pid != getpid ())
 495         return 1;
 496     }
 497
 498   return 0;
 499 }
 500
 501 /* Write the current process id to the file FILE.
 502    Returns 0 if successful, -1 if not.  */
 503 static int
 504 write_pid (const char *file)
 505 {
 506   FILE *fp;
 507
 508   fp = fopen (file, "w");
 509   if (fp == NULL)
 510     return -1;
 511
 512   fprintf (fp, "%d\n", getpid ());
 513
 514   int result = fflush (fp) || ferror (fp) ? -1 : 0;
 515
 516   fclose (fp);
 517
 518   return result;
 519 }