summaryrefslogtreecommitdiff
path: root/login/programs/utmpd.c
blob: e0648ebb42bd26f2fb5496aa7425a612c54aec2e (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
/* Copyright (C) 1997 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Mark Kettenis <kettenis@phys.uva.nl>, 1997.

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

   The GNU C Library 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
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public
   License along with the GNU C Library; see the file COPYING.LIB.  If not,
   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

#include <errno.h>
#include <fcntl.h>
#include <getopt.h>
#include <libintl.h>
#include <locale.h>
#include <pwd.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <string.h>
#include <sys/select.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/un.h>
#include <syslog.h>
#include <unistd.h>

#include "utmpd.h"
#include "utmpd-private.h"

#ifndef DEFAULT_USER
#define DEFAULT_USER	"daemon"
#endif

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

#define PACKAGE _libc_intl_domainname

/* Long options.  */
static const struct option long_options[] =
{
  { "debug", no_argument, NULL, 'd' },
  { "help", no_argument, NULL, 'h' },
  { "version", no_argument, NULL, 'V' },
  { NULL, 0, NULL, 0}
};

/* The UTMP database.  */
utmp_database *utmp_db;

/* The socket for read only requests.  */
int ro_sock = -1;

/* The socket for read/write requests.  */
int rw_sock = -1;


/* Prototypes for the local functions.  */
static void usage (int status) __attribute__ ((noreturn));
static void drop_priviliges (void);
static int make_socket (const char *name);
static void handle_requests (void) __attribute__ ((noreturn));
static void termination_handler (int signum);
static int check_pid (const char *file);
static int write_pid (const char *file);


int
main (int argc, char *argv[])
{
  mode_t mask;
  int debug;
  int do_help;
  int do_version;
  int opt;

  /* Set locale via LC_ALL.  */
  setlocale (LC_ALL, "");

  /* Set the text message domain.  */
  textdomain (PACKAGE);

  /* Initialize local variables.  */
  debug = 0;
  do_help = 0;
  do_version = 0;

  while ((opt = getopt_long (argc, argv, "dhV", long_options, NULL)) != -1)
    switch (opt)
      {
      case '\0':		/* Long option.  */
	break;
      case 'h':
	do_help = 1;
	break;
      case 'd':
	debug = 1;
	break;
      case 'V':
	do_version = 1;
	break;
      default:
	usage (EXIT_FAILURE);
      }

  /* Version information is reequested.  */
  if (do_version)
    {
      printf ("utmpd (GNU %s) %s\n", PACKAGE, VERSION);
      printf (_("\
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\
"), "1997");
      printf (_("Written by %s.\n"), "Mark Kettenis");

      exit (EXIT_SUCCESS);
    }

  /* Help is requested.  */
  if (do_help)
    usage (EXIT_SUCCESS);

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

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

  /* Cleanup files created by a previous `bind'.  */
  unlink (_PATH_UTMPD_RO);
  unlink (_PATH_UTMPD_RW);
  
  /* Open UTMP database.  */
  utmp_db = open_database (_PATH_UTMP "x", _PATH_UTMP);
  if (utmp_db == NULL)
    exit (EXIT_FAILURE);

  /* Create sockets, with the right permissions.  */
  mask = umask (S_IXUSR | S_IXGRP | S_IXOTH);
  ro_sock = make_socket (_PATH_UTMPD_RO);
  umask (S_IXUSR | S_IRWXG | S_IRWXO);
  rw_sock = make_socket (_PATH_UTMPD_RW);
  umask (mask);

  /* Set the sockets up to accept connections.  */
  if (listen (ro_sock, MAX_CONNECTIONS) < 0
      || listen (rw_sock, MAX_CONNECTIONS) < 0)
    error (EXIT_FAILURE, errno,
	   _("cannot enable socket to accept connections"));

  /* Behave like a daemon.  */
  if (!debug)
    {
      openlog ("utmpd", LOG_CONS | LOG_ODELAY, LOG_DAEMON);

      if (daemon (0, 0) < 0)
	error (EXIT_FAILURE, errno, _("cannot auto-background"));
      forked = 1;

      if (write_pid (_PATH_UTMPDPID) < 0)
	warning (errno, "%s", _PATH_UTMPDPID);

      /* Ignore job control signals.  */
      signal (SIGTTOU, SIG_IGN);
      signal (SIGTTIN, SIG_IGN);
      signal (SIGTSTP, SIG_IGN);
    }

  /* Drop priviliges.  */
  drop_priviliges ();

  /* Handle incoming requests.  */
  handle_requests ();
}


/* Display usage information and exit.  */
static void
usage (int status)
{
  if (status != EXIT_SUCCESS)
    fprintf (stderr, _("Try `%s --help' for more information.\n"),
	     program_invocation_name);
  else
    {
      printf (_("\
Usage: %s [OPTION]...\n\
  -d, --debug           do not fork and display messages on the current tty\n\
  -h, --help	        display this help and exit\n\
  -V, --version         output version information and exit\n"),
	      program_invocation_name);
      fputs (_("\
Report bugs using the `glibcbug' script to <bugs@gnu.ai.mit.edu>.\n"),
	     stdout);
    }

  exit (status);
}


/* Drop priviliges.  */
static void
drop_priviliges (void)
{
  struct passwd *pw;

  pw = getpwnam (DEFAULT_USER);
  if (pw)
    {
      seteuid (pw->pw_uid);
      setegid (pw->pw_gid);
    }
}


/* Make a socket in the file namespace using the filename NAME as the
   socket's address.  */
static int
make_socket (const char *name)
{
  struct sockaddr_un addr;
  size_t size;
  int sock;

  /* Create the socket.  */
  sock = socket (PF_UNIX, SOCK_STREAM, 0);
  if (sock < 0)
    error (EXIT_FAILURE, errno, _("cannot create socket"));

  /* Bind a name to the socket.  */
  addr.sun_family = AF_UNIX;
  strcpy (addr.sun_path, name);

  /* The size of the address is the offset of the start
     of the filename, plus its length, plus one for the
     terminating null byte. */
  size = (offsetof (struct sockaddr_un, sun_path)
	  + strlen (addr.sun_path));

  
  if (bind (sock, (struct sockaddr *) &addr, size) < 0)
    error (EXIT_FAILURE, errno, "%s", name);

  return sock;
}


/* Hanlde incoming requests.  */
static
void handle_requests (void)
{
  client_connection *connection;
  fd_set active_read_fd_set;
  fd_set active_write_fd_set;
  fd_set read_fd_set;
  fd_set write_fd_set;
  int fd;

  /* Initialize the set of active sockets.  */
  FD_ZERO (&active_read_fd_set);
  FD_ZERO (&active_write_fd_set);
  FD_SET (rw_sock, &active_read_fd_set);
  FD_SET (ro_sock, &active_read_fd_set);

  while (1)
    {
      /* Block until input arrives on one or more active sockets.  */
      read_fd_set = active_read_fd_set;
      write_fd_set = active_write_fd_set;
      if (select (FD_SETSIZE, &read_fd_set, &write_fd_set, NULL, NULL) < 0)
	error (EXIT_FAILURE, errno, _("cannot get input on sockets"));

      /* Service all the sockets with input pending.  */
      for (fd = 0; fd < FD_SETSIZE; fd++)
	{
	  if (FD_ISSET (fd, &read_fd_set))
	    {
	      if (fd == ro_sock || fd == rw_sock)
		{
		  int access = ((fd == rw_sock) ? (R_OK | W_OK) : R_OK);

		  connection = accept_connection (fd, access);
		  if (connection == NULL)
		    error (0, errno, _("cannot accept connection"));

		  FD_SET (connection->sock, &active_read_fd_set);
		}
	      else
		{
		  connection = find_connection (fd);
		  if (connection == NULL)
		    error (EXIT_FAILURE, 0, _("cannot find connection"));

		  if (read_data (connection) < 0)
		    {
		      close_connection (connection);
		      FD_CLR (fd, &active_read_fd_set);
		      FD_CLR (fd, &active_write_fd_set);
		    }

		  if (connection->write_ptr > connection->write_base)
		      FD_SET (fd, &active_write_fd_set);
		}
	    }
	  if (FD_ISSET (fd, &write_fd_set) &&
	      fd != rw_sock && fd != ro_sock)
	    {
	      connection = find_connection (fd);
	      if (connection == NULL)
		error (EXIT_FAILURE, 0, _("cannot find connection"));

	      if (write_data (connection) < 0)
		{
		  close_connection (connection);
		  FD_CLR (fd, &active_read_fd_set);
		  FD_CLR (fd, &active_write_fd_set);
		}

	      if (connection->write_ptr == connection->write_base)
		FD_CLR (fd, &active_write_fd_set);
	    }
	}
    }
}


/* Cleanup.  */
static void
termination_handler (int signum)
{
  /* Close sockets.  */
  close (ro_sock);
  close (rw_sock);

  /* Restore user id.  */
  seteuid (getuid ());

  /* Clean up the files created by `bind'.  */
  unlink (_PATH_UTMPD_RO);
  unlink (_PATH_UTMPD_RW);

  if (utmp_db)
    close_database (utmp_db);

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

  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 (_PATH_UTMPDPID, "r");
  if (fp)
    {
      pid_t pid;

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

      if (kill (pid, 0) == 0)
	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 (_PATH_UTMPDPID, "w");
  if (fp == NULL)
    return -1;

  fprintf (fp, "%d\n", getpid ());
  if (ferror (fp))
    return -1;

  fclose (fp);

  return 0;
}