nscd/connections.c

   1 /* Inner loops of cache daemon.
   2    Copyright (C) 1998, 1999, 2000, 2001 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1998.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, write to the Free
  18    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19    02111-1307 USA.  */
  20
  21 #include <assert.h>
  22 #include <error.h>
  23 #include <errno.h>
  24 #include <pthread.h>
  25 #include <stdlib.h>
  26 #include <unistd.h>
  27 #include <libintl.h>
  28 #include <arpa/inet.h>
  29 #include <sys/param.h>
  30 #include <sys/poll.h>
  31 #include <sys/socket.h>
  32 #include <sys/stat.h>
  33 #include <sys/un.h>
  34
  35 #include "nscd.h"
  36 #include "dbg_log.h"
  37
  38
  39 /* Mapping of request type to database.  */
  40 static const dbtype serv2db[LASTDBREQ + 1] =
  41 {
  42   [GETPWBYNAME] = pwddb,
  43   [GETPWBYUID] = pwddb,
  44   [GETGRBYNAME] = grpdb,
  45   [GETGRBYGID] = grpdb,
  46   [GETHOSTBYNAME] = hstdb,
  47   [GETHOSTBYNAMEv6] = hstdb,
  48   [GETHOSTBYADDR] = hstdb,
  49   [GETHOSTBYADDRv6] = hstdb,
  50 };
  51
  52 /* Map request type to a string.  */
  53 const char *serv2str[LASTREQ] =
  54 {
  55   [GETPWBYNAME] = "GETPWBYNAME",
  56   [GETPWBYUID] = "GETPWBYUID",
  57   [GETGRBYNAME] = "GETGRBYNAME",
  58   [GETGRBYGID] = "GETGRBYGID",
  59   [GETHOSTBYNAME] = "GETHOSTBYNAME",
  60   [GETHOSTBYNAMEv6] = "GETHOSTBYNAMEv6",
  61   [GETHOSTBYADDR] = "GETHOSTBYADDR",
  62   [GETHOSTBYADDRv6] = "GETHOSTBYADDRv6",
  63   [SHUTDOWN] = "SHUTDOWN",
  64   [GETSTAT] = "GETSTAT",
  65   [INVALIDATE] = "INVALIDATE"
  66 };
  67
  68 /* The control data structures for the services.  */
  69 static struct database dbs[lastdb] =
  70 {
  71   [pwddb] = {
  72     lock: PTHREAD_RWLOCK_WRITER_NONRECURSIVE_INITIALIZER_NP,
  73     enabled: 0,
  74     check_file: 1,
  75     filename: "/etc/passwd",
  76     module: 211,
  77     disabled_iov: &pwd_iov_disabled,
  78     postimeout: 3600,
  79     negtimeout: 20
  80   },
  81   [grpdb] = {
  82     lock: PTHREAD_RWLOCK_WRITER_NONRECURSIVE_INITIALIZER_NP,
  83     enabled: 0,
  84     check_file: 1,
  85     filename: "/etc/group",
  86     module: 211,
  87     disabled_iov: &grp_iov_disabled,
  88     postimeout: 3600,
  89     negtimeout: 60
  90   },
  91   [hstdb] = {
  92     lock: PTHREAD_RWLOCK_WRITER_NONRECURSIVE_INITIALIZER_NP,
  93     enabled: 0,
  94     check_file: 1,
  95     filename: "/etc/hosts",
  96     module: 211,
  97     disabled_iov: &hst_iov_disabled,
  98     postimeout: 3600,
  99     negtimeout: 20
 100   }
 101 };
 102
 103 /* Number of seconds between two cache pruning runs.  */
 104 #define CACHE_PRUNE_INTERVAL    15
 105
 106 /* Number of threads to use.  */
 107 int nthreads = -1;
 108
 109 /* Socket for incoming connections.  */
 110 static int sock;
 111
 112
 113 /* Initialize database information structures.  */
 114 void
 115 nscd_init (const char *conffile)
 116 {
 117   struct sockaddr_un sock_addr;
 118   size_t cnt;
 119
 120   /* Read the configuration file.  */
 121   if (nscd_parse_file (conffile, dbs) != 0)
 122     {
 123       /* We couldn't read the configuration file.  Disable all services
 124          by shutting down the srever.  */
 125       dbg_log (_("cannot read configuration file; this is fatal"));
 126       exit (1);
 127     }
 128   if (nthreads == -1)
 129     /* No configuration for this value, assume a default.  */
 130     nthreads = 2 * lastdb;
 131
 132   for (cnt = 0; cnt < lastdb; ++cnt)
 133     if (dbs[cnt].enabled)
 134       {
 135         pthread_rwlock_init (&dbs[cnt].lock, NULL);
 136
 137         dbs[cnt].array = (struct hashentry **)
 138           calloc (dbs[cnt].module, sizeof (struct hashentry *));
 139         if (dbs[cnt].array == NULL)
 140           error (EXIT_FAILURE, errno, "while allocating cache");
 141
 142         if (dbs[cnt].check_file)
 143           {
 144             /* We need the modification date of the file.  */
 145             struct stat st;
 146
 147             if (stat (dbs[cnt].filename, &st) < 0)
 148               {
 149                 char buf[128];
 150                 /* We cannot stat() the file, disable file checking.  */
 151                 dbg_log (_("cannot stat() file `%s': %s"),
 152                          dbs[cnt].filename,
 153                          strerror_r (errno, buf, sizeof (buf)));
 154                 dbs[cnt].check_file = 0;
 155               }
 156             else
 157               dbs[cnt].file_mtime = st.st_mtime;
 158           }
 159       }
 160
 161   /* Create the socket.  */
 162   sock = socket (AF_UNIX, SOCK_STREAM, 0);
 163   if (sock < 0)
 164     {
 165       dbg_log (_("cannot open socket: %s"), strerror (errno));
 166       exit (1);
 167     }
 168   /* Bind a name to the socket.  */
 169   sock_addr.sun_family = AF_UNIX;
 170   strcpy (sock_addr.sun_path, _PATH_NSCDSOCKET);
 171   if (bind (sock, (struct sockaddr *) &sock_addr, sizeof (sock_addr)) < 0)
 172     {
 173       dbg_log ("%s: %s", _PATH_NSCDSOCKET, strerror (errno));
 174       exit (1);
 175     }
 176
 177   /* Set permissions for the socket.  */
 178   chmod (_PATH_NSCDSOCKET, 0666);
 179
 180   /* Set the socket up to accept connections.  */
 181   if (listen (sock, SOMAXCONN) < 0)
 182     {
 183       dbg_log (_("cannot enable socket to accept connections: %s"),
 184                strerror (errno));
 185       exit (1);
 186     }
 187 }
 188
 189
 190 /* Close the connections.  */
 191 void
 192 close_sockets (void)
 193 {
 194   close (sock);
 195 }
 196
 197 static void
 198 invalidate_cache (char *key)
 199 {
 200   dbtype number;
 201
 202   if (strcmp (key, "passwd") == 0)
 203     number = pwddb;
 204   else if (strcmp (key, "group") == 0)
 205     number = grpdb;
 206   else if (strcmp (key, "hosts") == 0)
 207     number = hstdb;
 208   else return;
 209
 210   if (dbs[number].enabled)
 211     prune_cache (&dbs[number], LONG_MAX);
 212 }
 213
 214
 215 /* Handle new request.  */
 216 static void
 217 handle_request (int fd, request_header *req, void *key, uid_t uid)
 218 {
 219   if (debug_level > 0)
 220     dbg_log (_("handle_request: request received (Version = %d)"),
 221              req->version);
 222
 223   if (req->version != NSCD_VERSION)
 224     {
 225       dbg_log (_("\
 226 cannot handle old request version %d; current version is %d"),
 227                req->version, NSCD_VERSION);
 228       return;
 229     }
 230
 231   if (req->type >= GETPWBYNAME && req->type <= LASTDBREQ)
 232     {
 233       struct hashentry *cached;
 234       struct database *db = &dbs[serv2db[req->type]];
 235
 236       if (debug_level > 0)
 237         {
 238           if (req->type == GETHOSTBYADDR || req->type == GETHOSTBYADDRv6)
 239             {
 240               char buf[INET6_ADDRSTRLEN];
 241
 242               dbg_log ("\t%s (%s)", serv2str[req->type],
 243                        inet_ntop (req->type == GETHOSTBYADDR
 244                                   ? AF_INET : AF_INET6,
 245                                   key, buf, sizeof (buf)));
 246             }
 247           else
 248             dbg_log ("\t%s (%s)", serv2str[req->type], (char *)key);
 249         }
 250
 251       /* Is this service enabled?  */
 252       if (!db->enabled)
 253         {
 254           /* No, sent the prepared record.  */
 255           if (TEMP_FAILURE_RETRY (write (fd, db->disabled_iov->iov_base,
 256                                          db->disabled_iov->iov_len))
 257               != db->disabled_iov->iov_len)
 258             {
 259               /* We have problems sending the result.  */
 260               char buf[256];
 261               dbg_log (_("cannot write result: %s"),
 262                        strerror_r (errno, buf, sizeof (buf)));
 263             }
 264
 265           return;
 266         }
 267
 268       /* Be sure we can read the data.  */
 269       pthread_rwlock_rdlock (&db->lock);
 270
 271       /* See whether we can handle it from the cache.  */
 272       cached = (struct hashentry *) cache_search (req->type, key, req->key_len,
 273                                                   db, uid);
 274       if (cached != NULL)
 275         {
 276           /* Hurray it's in the cache.  */
 277           if (TEMP_FAILURE_RETRY (write (fd, cached->packet, cached->total))
 278               != cached->total)
 279             {
 280               /* We have problems sending the result.  */
 281               char buf[256];
 282               dbg_log (_("cannot write result: %s"),
 283                        strerror_r (errno, buf, sizeof (buf)));
 284             }
 285
 286           pthread_rwlock_unlock (&db->lock);
 287
 288           return;
 289         }
 290
 291       pthread_rwlock_unlock (&db->lock);
 292     }
 293   else if (debug_level > 0)
 294     {
 295       if (req->type == INVALIDATE)
 296         dbg_log ("\t%s (%s)", serv2str[req->type], (char *)key);
 297       else
 298         dbg_log ("\t%s", serv2str[req->type]);
 299     }
 300
 301   /* Handle the request.  */
 302   switch (req->type)
 303     {
 304     case GETPWBYNAME:
 305       addpwbyname (&dbs[serv2db[req->type]], fd, req, key, uid);
 306       break;
 307
 308     case GETPWBYUID:
 309       addpwbyuid (&dbs[serv2db[req->type]], fd, req, key, uid);
 310       break;
 311
 312     case GETGRBYNAME:
 313       addgrbyname (&dbs[serv2db[req->type]], fd, req, key, uid);
 314       break;
 315
 316     case GETGRBYGID:
 317       addgrbygid (&dbs[serv2db[req->type]], fd, req, key, uid);
 318       break;
 319
 320     case GETHOSTBYNAME:
 321       addhstbyname (&dbs[serv2db[req->type]], fd, req, key, uid);
 322       break;
 323
 324     case GETHOSTBYNAMEv6:
 325       addhstbynamev6 (&dbs[serv2db[req->type]], fd, req, key, uid);
 326       break;
 327
 328     case GETHOSTBYADDR:
 329       addhstbyaddr (&dbs[serv2db[req->type]], fd, req, key, uid);
 330       break;
 331
 332     case GETHOSTBYADDRv6:
 333       addhstbyaddrv6 (&dbs[serv2db[req->type]], fd, req, key, uid);
 334       break;
 335
 336     case GETSTAT:
 337     case SHUTDOWN:
 338     case INVALIDATE:
 339       /* Accept shutdown, getstat and invalidate only from root */
 340       if (secure_in_use && uid == 0)
 341         {
 342           if (req->type == GETSTAT)
 343             send_stats (fd, dbs);
 344           else if (req->type == INVALIDATE)
 345             invalidate_cache (key);
 346           else
 347             termination_handler (0);
 348         }
 349       else
 350         {
 351           struct ucred caller;
 352           socklen_t optlen = sizeof (caller);
 353
 354           /* Some systems have no SO_PEERCRED implementation.  They don't
 355              care about security so we don't as well.  */
 356 #ifdef SO_PEERCRED
 357           if (getsockopt (fd, SOL_SOCKET, SO_PEERCRED, &caller, &optlen) < 0)
 358             {
 359               char buf[256];
 360
 361               dbg_log (_("error getting callers id: %s"),
 362                        strerror_r (errno, buf, sizeof (buf)));
 363             }
 364           else
 365             if (caller.uid == 0)
 366 #endif
 367               {
 368                 if (req->type == GETSTAT)
 369                   send_stats (fd, dbs);
 370                 else if (req->type == INVALIDATE)
 371                   invalidate_cache (key);
 372                 else
 373                   termination_handler (0);
 374               }
 375         }
 376       break;
 377
 378     default:
 379       /* Ignore the command, it's nothing we know.  */
 380       break;
 381     }
 382 }
 383
 384
 385 /* This is the main loop.  It is replicated in different threads but the
 386    `poll' call makes sure only one thread handles an incoming connection.  */
 387 static void *
 388 __attribute__ ((__noreturn__))
 389 nscd_run (void *p)
 390 {
 391   long int my_number = (long int) p;
 392   struct pollfd conn;
 393   int run_prune = my_number < lastdb && dbs[my_number].enabled;
 394   time_t now = time (NULL);
 395   time_t next_prune = now + CACHE_PRUNE_INTERVAL;
 396   int timeout = run_prune ? 1000 * (next_prune - now) : -1;
 397
 398   conn.fd = sock;
 399   conn.events = POLLRDNORM;
 400
 401   while (1)
 402     {
 403       int nr = poll (&conn, 1, timeout);
 404
 405       if (nr == 0)
 406         {
 407           /* The `poll' call timed out.  It's time to clean up the cache.  */
 408           assert (my_number < lastdb);
 409           now = time (NULL);
 410           prune_cache (&dbs[my_number], now);
 411           next_prune = now + CACHE_PRUNE_INTERVAL;
 412           timeout = 1000 * (next_prune - now);
 413           continue;
 414         }
 415
 416       /* We have a new incoming connection.  */
 417       if (conn.revents & (POLLRDNORM|POLLERR|POLLHUP|POLLNVAL))
 418         {
 419           /* Accept the connection.  */
 420           int fd = accept (conn.fd, NULL, NULL);
 421           request_header req;
 422           char buf[256];
 423           uid_t uid = 0;
 424
 425           if (fd < 0)
 426             {
 427               dbg_log (_("while accepting connection: %s"),
 428                        strerror_r (errno, buf, sizeof (buf)));
 429               continue;
 430             }
 431
 432           /* Now read the request.  */
 433           if (TEMP_FAILURE_RETRY (read (fd, &req, sizeof (req)))
 434               != sizeof (req))
 435             {
 436               dbg_log (_("short read while reading request: %s"),
 437                        strerror_r (errno, buf, sizeof (buf)));
 438               close (fd);
 439               continue;
 440             }
 441
 442           /* Some systems have no SO_PEERCRED implementation.  They don't
 443              care about security so we don't as well.  */
 444 #ifdef SO_PEERCRED
 445           if (secure_in_use)
 446             {
 447               struct ucred caller;
 448               socklen_t optlen = sizeof (caller);
 449
 450               if (getsockopt (fd, SOL_SOCKET, SO_PEERCRED,
 451                               &caller, &optlen) < 0)
 452                 {
 453                   dbg_log (_("error getting callers id: %s"),
 454                            strerror_r (errno, buf, sizeof (buf)));
 455                   close (fd);
 456                   continue;
 457                 }
 458
 459               if (req.type < GETPWBYNAME || req.type > LASTDBREQ
 460                   || secure[serv2db[req.type]])
 461                 uid = caller.uid;
 462             }
 463 #endif
 464
 465           /* It should not be possible to crash the nscd with a silly
 466              request (i.e., a terribly large key).  We limit the size
 467              to 1kb.  */
 468           if (req.key_len < 0 || req.key_len > 1024)
 469             {
 470               dbg_log (_("key length in request too long: %d"), req.key_len);
 471               close (fd);
 472               continue;
 473             }
 474           else
 475             {
 476               /* Get the key.  */
 477               char keybuf[req.key_len];
 478
 479               if (TEMP_FAILURE_RETRY (read (fd, keybuf, req.key_len))
 480                   != req.key_len)
 481                 {
 482                   dbg_log (_("short read while reading request key: %s"),
 483                            strerror_r (errno, buf, sizeof (buf)));
 484                   close (fd);
 485                   continue;
 486                 }
 487
 488               /* Phew, we got all the data, now process it.  */
 489               handle_request (fd, &req, keybuf, uid);
 490
 491               /* We are done.  */
 492               close (fd);
 493             }
 494         }
 495
 496       if (run_prune)
 497         {
 498           now = time (NULL);
 499           timeout = now < next_prune ? 1000 * (next_prune - now) : 0;
 500         }
 501     }
 502 }
 503
 504
 505 /* Start all the threads we want.  The initial process is thread no. 1.  */
 506 void
 507 start_threads (void)
 508 {
 509   long int i;
 510   pthread_attr_t attr;
 511   pthread_t th;
 512
 513   pthread_attr_init (&attr);
 514   pthread_attr_setdetachstate (&attr, PTHREAD_CREATE_DETACHED);
 515
 516   /* We allow less than LASTDB threads only for debugging.  */
 517   if (debug_level == 0)
 518     nthreads = MAX (nthreads, lastdb);
 519
 520   for (i = 1; i < nthreads; ++i)
 521     pthread_create (&th, &attr, nscd_run, (void *) i);
 522
 523   pthread_attr_destroy (&attr);
 524
 525   nscd_run ((void *) 0);
 526 }