summaryrefslogtreecommitdiff
path: root/nscd/nscd.c
blob: 86033a79b6ebf8541dd27611dc737bd442c324e3 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
/* Copyright (c) 1998-2017 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Thorsten Kukuk <kukuk@suse.de>, 1998.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published
   by the Free Software Foundation; version 2 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, see <http://www.gnu.org/licenses/>.  */

/* nscd - Name Service Cache Daemon. Caches passwd, group, and hosts.  */

#include <argp.h>
#include <assert.h>
#include <dirent.h>
#include <errno.h>
#include <error.h>
#include <fcntl.h>
#include <libintl.h>
#include <locale.h>
#include <paths.h>
#include <pthread.h>
#include <signal.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>
#include <sys/mman.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/uio.h>
#include <sys/un.h>
#include <sys/wait.h>
#include <stdarg.h>

#include "dbg_log.h"
#include "nscd.h"
#include "selinux.h"
#include "../nss/nsswitch.h"
#include <device-nrs.h>
#ifdef HAVE_INOTIFY
# include <sys/inotify.h>
#endif
#include <kernel-features.h>

/* Get libc version number.  */
#include <version.h>

#define PACKAGE _libc_intl_domainname

int do_shutdown;
int disabled_passwd;
int disabled_group;

typedef enum
{
  /* Running in background as daemon.  */
  RUN_DAEMONIZE,
  /* Running in foreground but otherwise behave like a daemon,
     i.e., detach from terminal and use syslog.  This allows
     better integration with services like systemd.  */
  RUN_FOREGROUND,
  /* Run in foreground in debug mode.  */
  RUN_DEBUG
} run_modes;

static run_modes run_mode = RUN_DAEMONIZE;

static const char *conffile = _PATH_NSCDCONF;

time_t start_time;

uintptr_t pagesize_m1;

int paranoia;
time_t restart_time;
time_t restart_interval = RESTART_INTERVAL;
const char *oldcwd;
uid_t old_uid;
gid_t old_gid;

static int check_pid (const char *file);
static int write_pid (const char *file);
static int monitor_child (int fd);

/* Name and version of program.  */
static void print_version (FILE *stream, struct argp_state *state);
void (*argp_program_version_hook) (FILE *, struct argp_state *) = print_version;

/* Function to print some extra text in the help message.  */
static char *more_help (int key, const char *text, void *input);

/* Definitions of arguments for argp functions.  */
static const struct argp_option options[] =
{
  { "config-file", 'f', N_("NAME"), 0,
    N_("Read configuration data from NAME") },
  { "debug", 'd', NULL, 0,
    N_("Do not fork and display messages on the current tty") },
  { "foreground", 'F', NULL, 0,
    N_("Do not fork, but otherwise behave like a daemon") },
  { "nthreads", 't', N_("NUMBER"), 0, N_("Start NUMBER threads") },
  { "shutdown", 'K', NULL, 0, N_("Shut the server down") },
  { "statistics", 'g', NULL, 0, N_("Print current configuration statistics") },
  { "invalidate", 'i', N_("TABLE"), 0,
    N_("Invalidate the specified cache") },
  { "secure", 'S', N_("TABLE,yes"), OPTION_HIDDEN,
    N_("Use separate cache for each user")},
  { NULL, 0, NULL, 0, NULL }
};

/* Short description of program.  */
static const char doc[] = N_("Name Service Cache Daemon.");

/* Prototype for option handler.  */
static error_t parse_opt (int key, char *arg, struct argp_state *state);

/* Data structure to communicate with argp functions.  */
static struct argp argp =
{
  options, parse_opt, NULL, doc, NULL, more_help
};

/* True if only statistics are requested.  */
static bool get_stats;
static int parent_fd = -1;

int
main (int argc, char **argv)
{
  int remaining;

  /* Set locale via LC_ALL.  */
  setlocale (LC_ALL, "");
  /* Set the text message domain.  */
  textdomain (PACKAGE);

  /* Determine if the kernel has SELinux support.  */
  nscd_selinux_enabled (&selinux_enabled);

  /* Parse and process arguments.  */
  argp_parse (&argp, argc, argv, 0, &remaining, NULL);

  if (remaining != argc)
    {
      error (0, 0, gettext ("wrong number of arguments"));
      argp_help (&argp, stdout, ARGP_HELP_SEE, program_invocation_short_name);
      exit (1);
    }

  /* Read the configuration file.  */
  if (nscd_parse_file (conffile, dbs) != 0)
    /* We couldn't read the configuration file.  We don't start the
       server.  */
    error (EXIT_FAILURE, 0,
	   _("failure while reading configuration file; this is fatal"));

  /* Do we only get statistics?  */
  if (get_stats)
    /* Does not return.  */
    receive_print_stats ();

  /* Check if we are already running. */
  if (check_pid (_PATH_NSCDPID))
    error (EXIT_FAILURE, 0, _("already running"));

  /* Remember when we started.  */
  start_time = time (NULL);

  /* Determine page size.  */
  pagesize_m1 = getpagesize () - 1;

  if (run_mode == RUN_DAEMONIZE || run_mode == RUN_FOREGROUND)
    {
      int i;
      pid_t pid;

      /* Behave like a daemon.  */
      if (run_mode == RUN_DAEMONIZE)
	{
	  int fd[2];

	  if (pipe (fd) != 0)
	    error (EXIT_FAILURE, errno,
		   _("cannot create a pipe to talk to the child"));

	  pid = fork ();
	  if (pid == -1)
	    error (EXIT_FAILURE, errno, _("cannot fork"));
	  if (pid != 0)
	    {
	      /* The parent only reads from the child.  */
	      close (fd[1]);
	      exit (monitor_child (fd[0]));
	    }
	  else
	    {
	      /* The child only writes to the parent.  */
	      close (fd[0]);
	      parent_fd = fd[1];
	    }
	}

      int nullfd = open (_PATH_DEVNULL, O_RDWR);
      if (nullfd != -1)
	{
	  struct stat64 st;

	  if (fstat64 (nullfd, &st) == 0 && S_ISCHR (st.st_mode) != 0
#if defined DEV_NULL_MAJOR && defined DEV_NULL_MINOR
	      && st.st_rdev == makedev (DEV_NULL_MAJOR, DEV_NULL_MINOR)
#endif
	      )
	    {
	      /* It is the /dev/null special device alright.  */
	      (void) dup2 (nullfd, STDIN_FILENO);
	      (void) dup2 (nullfd, STDOUT_FILENO);
	      (void) dup2 (nullfd, STDERR_FILENO);

	      if (nullfd > 2)
		close (nullfd);
	    }
	  else
	    {
	      /* Ugh, somebody is trying to play a trick on us.  */
	      close (nullfd);
	      nullfd = -1;
	    }
	}
      int min_close_fd = nullfd == -1 ? 0 : STDERR_FILENO + 1;

      DIR *d = opendir ("/proc/self/fd");
      if (d != NULL)
	{
	  struct dirent64 *dirent;
	  int dfdn = dirfd (d);

	  while ((dirent = readdir64 (d)) != NULL)
	    {
	      char *endp;
	      long int fdn = strtol (dirent->d_name, &endp, 10);

	      if (*endp == '\0' && fdn != dfdn && fdn >= min_close_fd
		  && fdn != parent_fd)
		close ((int) fdn);
	    }

	  closedir (d);
	}
      else
	for (i = min_close_fd; i < getdtablesize (); i++)
	  if (i != parent_fd)
	    close (i);

      setsid ();

      if (chdir ("/") != 0)
	do_exit (EXIT_FAILURE, errno,
		 _("cannot change current working directory to \"/\""));

      openlog ("nscd", LOG_CONS | LOG_ODELAY, LOG_DAEMON);

      if (write_pid (_PATH_NSCDPID) < 0)
	dbg_log ("%s: %s", _PATH_NSCDPID, strerror (errno));

      if (!init_logfile ())
	dbg_log (_("Could not create log file"));

      /* Ignore job control signals.  */
      signal (SIGTTOU, SIG_IGN);
      signal (SIGTTIN, SIG_IGN);
      signal (SIGTSTP, SIG_IGN);
    }
  else
    /* In debug mode we are not paranoid.  */
    paranoia = 0;

  signal (SIGINT, termination_handler);
  signal (SIGQUIT, termination_handler);
  signal (SIGTERM, termination_handler);
  signal (SIGPIPE, SIG_IGN);

  /* Cleanup files created by a previous 'bind'.  */
  unlink (_PATH_NSCDSOCKET);

#ifdef HAVE_INOTIFY
  /* Use inotify to recognize changed files.  */
  inotify_fd = inotify_init1 (IN_NONBLOCK);
# ifndef __ASSUME_IN_NONBLOCK
  if (inotify_fd == -1 && errno == ENOSYS)
    {
      inotify_fd = inotify_init ();
      if (inotify_fd != -1)
	fcntl (inotify_fd, F_SETFL, O_RDONLY | O_NONBLOCK);
    }
# endif
#endif

#ifdef USE_NSCD
  /* Make sure we do not get recursive calls.  */
  __nss_disable_nscd (register_traced_file);
#endif

  /* Init databases.  */
  nscd_init ();

  /* Start the SELinux AVC.  */
  if (selinux_enabled)
    nscd_avc_init ();

  /* Handle incoming requests */
  start_threads ();

  return 0;
}


static void __attribute__ ((noreturn))
invalidate_db (const char *dbname)
{
  int sock = nscd_open_socket ();

  if (sock == -1)
    exit (EXIT_FAILURE);

  size_t dbname_len = strlen (dbname) + 1;
  size_t reqlen = sizeof (request_header) + dbname_len;
  struct
  {
    request_header req;
    char dbname[];
  } *reqdata = alloca (reqlen);

  reqdata->req.key_len = dbname_len;
  reqdata->req.version = NSCD_VERSION;
  reqdata->req.type = INVALIDATE;
  memcpy (reqdata->dbname, dbname, dbname_len);

  ssize_t nbytes = TEMP_FAILURE_RETRY (send (sock, reqdata, reqlen,
					     MSG_NOSIGNAL));

  if (nbytes != reqlen)
    {
      int err = errno;
      close (sock);
      error (EXIT_FAILURE, err, _("write incomplete"));
    }

  /* Wait for ack.  Older nscd just closed the socket when
     prune_cache finished, silently ignore that.  */
  int32_t resp = 0;
  nbytes = TEMP_FAILURE_RETRY (read (sock, &resp, sizeof (resp)));
  if (nbytes != 0 && nbytes != sizeof (resp))
    {
      int err = errno;
      close (sock);
      error (EXIT_FAILURE, err, _("cannot read invalidate ACK"));
    }

  close (sock);

  if (resp != 0)
    error (EXIT_FAILURE, resp, _("invalidation failed"));

  exit (0);
}

static void __attribute__ ((noreturn))
send_shutdown (void)
{
  int sock = nscd_open_socket ();

  if (sock == -1)
    exit (EXIT_FAILURE);

  request_header req;
  req.version = NSCD_VERSION;
  req.type = SHUTDOWN;
  req.key_len = 0;

  ssize_t nbytes = TEMP_FAILURE_RETRY (send (sock, &req, sizeof req,
                                             MSG_NOSIGNAL));
  close (sock);
  exit (nbytes != sizeof (request_header) ? EXIT_FAILURE : EXIT_SUCCESS);
}

/* Handle program arguments.  */
static error_t
parse_opt (int key, char *arg, struct argp_state *state)
{
  switch (key)
    {
    case 'd':
      ++debug_level;
      run_mode = RUN_DEBUG;
      break;

    case 'F':
      run_mode = RUN_FOREGROUND;
      break;

    case 'f':
      conffile = arg;
      break;

    case 'K':
      if (getuid () != 0)
	error (4, 0, _("Only root is allowed to use this option!"));
      else
        send_shutdown ();
      break;

    case 'g':
      get_stats = true;
      break;

    case 'i':
      {
        /* Validate the database name.  */

        dbtype cnt;
        for (cnt = pwddb; cnt < lastdb; ++cnt)
          if (strcmp (arg, dbnames[cnt]) == 0)
            break;

        if (cnt == lastdb)
          {
            argp_error (state, _("'%s' is not a known database"), arg);
            return EINVAL;
          }
      }
      if (getuid () != 0)
	error (4, 0, _("Only root is allowed to use this option!"));
      else
        invalidate_db (arg);
      break;

    case 't':
      nthreads = atol (arg);
      break;

    case 'S':
      error (0, 0, _("secure services not implemented anymore"));
      break;

    default:
      return ARGP_ERR_UNKNOWN;
    }

  return 0;
}

/* Print bug-reporting information in the help message.  */
static char *
more_help (int key, const char *text, void *input)
{
  switch (key)
    {
    case ARGP_KEY_HELP_EXTRA:
      {
	/* We print some extra information.  */

	char *tables = xstrdup (dbnames[0]);
	for (dbtype i = 1; i < lastdb; ++i)
	  {
	    char *more_tables;
	    if (asprintf (&more_tables, "%s %s", tables, dbnames[i]) < 0)
	      more_tables = NULL;
	    free (tables);
	    if (more_tables == NULL)
	      return NULL;
	    tables = more_tables;
	  }

	char *tp;
	if (asprintf (&tp, gettext ("\
Supported tables:\n\
%s\n\
\n\
For bug reporting instructions, please see:\n\
%s.\n\
"), tables, REPORT_BUGS_TO) < 0)
	  tp = NULL;
	free (tables);
	return tp;
      }

    default:
      break;
    }

  return (char *) text;
}

/* Print the version information.  */
static void
print_version (FILE *stream, struct argp_state *state)
{
  fprintf (stream, "nscd %s%s\n", PKGVERSION, VERSION);
  fprintf (stream, gettext ("\
Copyright (C) %s Free Software Foundation, Inc.\n\
This is free software; see the source for copying conditions.  There is NO\n\
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.\n\
"), "2016");
  fprintf (stream, gettext ("Written by %s.\n"),
	   "Thorsten Kukuk and Ulrich Drepper");
}


/* Create a socket connected to a name.  */
int
nscd_open_socket (void)
{
  struct sockaddr_un addr;
  int sock;

  sock = socket (PF_UNIX, SOCK_STREAM, 0);
  if (sock < 0)
    return -1;

  addr.sun_family = AF_UNIX;
  assert (sizeof (addr.sun_path) >= sizeof (_PATH_NSCDSOCKET));
  strcpy (addr.sun_path, _PATH_NSCDSOCKET);
  if (connect (sock, (struct sockaddr *) &addr, sizeof (addr)) < 0)
    {
      close (sock);
      return -1;
    }

  return sock;
}


/* Cleanup.  */
void
termination_handler (int signum)
{
  close_sockets ();

  /* Clean up the file created by 'bind'.  */
  unlink (_PATH_NSCDSOCKET);

  /* Clean up pid file.  */
  unlink (_PATH_NSCDPID);

  // XXX Terminate threads.

  /* Synchronize memory.  */
  for (int cnt = 0; cnt < lastdb; ++cnt)
    {
      if (!dbs[cnt].enabled || dbs[cnt].head == NULL)
	continue;

      /* Make sure nobody keeps using the database.  */
      dbs[cnt].head->timestamp = 0;

      if (dbs[cnt].persistent)
	// XXX async OK?
	msync (dbs[cnt].head, dbs[cnt].memsize, MS_ASYNC);
    }

  _exit (EXIT_SUCCESS);
}

/* Returns 1 if the process in pid file FILE is running, 0 if not.  */
static int
check_pid (const char *file)
{
  FILE *fp;

  fp = fopen (file, "r");
  if (fp)
    {
      pid_t pid;
      int n;

      n = fscanf (fp, "%d", &pid);
      fclose (fp);

      /* If we cannot parse the file default to assuming nscd runs.
	 If the PID is alive, assume it is running.  That all unless
	 the PID is the same as the current process' since tha latter
	 can mean we re-exec.  */
      if ((n != 1 || kill (pid, 0) == 0) && pid != getpid ())
	return 1;
    }

  return 0;
}

/* Write the current process id to the file FILE.
   Returns 0 if successful, -1 if not.  */
static int
write_pid (const char *file)
{
  FILE *fp;

  fp = fopen (file, "w");
  if (fp == NULL)
    return -1;

  fprintf (fp, "%d\n", getpid ());

  int result = fflush (fp) || ferror (fp) ? -1 : 0;

  fclose (fp);

  return result;
}

static int
monitor_child (int fd)
{
  int child_ret = 0;
  int ret = read (fd, &child_ret, sizeof (child_ret));

  /* The child terminated with an error, either via exit or some other abnormal
     method, like a segfault.  */
  if (ret <= 0 || child_ret != 0)
    {
      int status;
      int err = wait (&status);

      if (err < 0)
	{
	  fprintf (stderr, _("'wait' failed\n"));
	  return 1;
	}

      if (WIFEXITED (status))
	{
	  child_ret = WEXITSTATUS (status);
	  fprintf (stderr, _("child exited with status %d\n"), child_ret);
	}
      if (WIFSIGNALED (status))
	{
	  child_ret = WTERMSIG (status);
	  fprintf (stderr, _("child terminated by signal %d\n"), child_ret);
	}
    }

  /* We have the child status, so exit with that code.  */
  close (fd);

  return child_ret;
}

void
do_exit (int child_ret, int errnum, const char *format, ...)
{
  if (parent_fd != -1)
    {
      int ret __attribute__ ((unused));
      ret = write (parent_fd, &child_ret, sizeof (child_ret));
      assert (ret == sizeof (child_ret));
      close (parent_fd);
    }

  if (format != NULL)
    {
      /* Emulate error() since we don't have a va_list variant for it.  */
      va_list argp;

      fflush (stdout);

      fprintf (stderr, "%s: ", program_invocation_name);

      va_start (argp, format);
      vfprintf (stderr, format, argp);
      va_end (argp);

      fprintf (stderr, ": %s\n", strerror (errnum));
      fflush (stderr);
    }

  /* Finally, exit.  */
  exit (child_ret);
}

void
notify_parent (int child_ret)
{
  if (parent_fd == -1)
    return;

  int ret __attribute__ ((unused));
  ret = write (parent_fd, &child_ret, sizeof (child_ret));
  assert (ret == sizeof (child_ret));
  close (parent_fd);
  parent_fd = -1;
}