source3/locking/share_mode_lock.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    Locking functions
   4    Copyright (C) Andrew Tridgell 1992-2000
   5    Copyright (C) Jeremy Allison 1992-2006
   6    Copyright (C) Volker Lendecke 2005
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  20
  21    Revision History:
  22
  23    12 aug 96: Erik.Devriendt@te6.siemens.be
  24    added support for shared memory implementation of share mode locking
  25
  26    May 1997. Jeremy Allison (jallison@whistle.com). Modified share mode
  27    locking to deal with multiple share modes per open file.
  28
  29    September 1997. Jeremy Allison (jallison@whistle.com). Added oplock
  30    support.
  31
  32    rewritten completely to use new tdb code. Tridge, Dec '99
  33
  34    Added POSIX locking support. Jeremy Allison (jeremy@valinux.com), Apr. 2000.
  35    Added Unix Extensions POSIX locking support. Jeremy Allison Mar 2006.
  36 */
  37
  38 #include "includes.h"
  39 #include "system/filesys.h"
  40 #include "locking/proto.h"
  41 #include "smbd/globals.h"
  42 #include "dbwrap/dbwrap.h"
  43 #include "dbwrap/dbwrap_open.h"
  44 #include "../libcli/security/security.h"
  45 #include "serverid.h"
  46 #include "messages.h"
  47 #include "util_tdb.h"
  48 #include "../librpc/gen_ndr/ndr_open_files.h"
  49
  50 #undef DBGC_CLASS
  51 #define DBGC_CLASS DBGC_LOCKING
  52
  53 #define NO_LOCKING_COUNT (-1)
  54
  55 /* the locking database handle */
  56 static struct db_context *lock_db;
  57
  58 static bool locking_init_internal(bool read_only)
  59 {
  60         brl_init(read_only);
  61
  62         if (lock_db)
  63                 return True;
  64
  65         lock_db = db_open(NULL, lock_path("locking.tdb"),
  66                           lp_open_files_db_hash_size(),
  67                           TDB_DEFAULT|TDB_VOLATILE|TDB_CLEAR_IF_FIRST|TDB_INCOMPATIBLE_HASH,
  68                           read_only?O_RDONLY:O_RDWR|O_CREAT, 0644,
  69                           DBWRAP_LOCK_ORDER_1);
  70
  71         if (!lock_db) {
  72                 DEBUG(0,("ERROR: Failed to initialise locking database\n"));
  73                 return False;
  74         }
  75
  76         if (!posix_locking_init(read_only))
  77                 return False;
  78
  79         return True;
  80 }
  81
  82 bool locking_init(void)
  83 {
  84         return locking_init_internal(false);
  85 }
  86
  87 bool locking_init_readonly(void)
  88 {
  89         return locking_init_internal(true);
  90 }
  91
  92 /*******************************************************************
  93  Deinitialize the share_mode management.
  94 ******************************************************************/
  95
  96 bool locking_end(void)
  97 {
  98         brl_shutdown();
  99         TALLOC_FREE(lock_db);
 100         return true;
 101 }
 102
 103 /*******************************************************************
 104  Form a static locking key for a dev/inode pair.
 105 ******************************************************************/
 106
 107 static TDB_DATA locking_key(const struct file_id *id, struct file_id *tmp)
 108 {
 109         *tmp = *id;
 110         return make_tdb_data((const uint8_t *)tmp, sizeof(*tmp));
 111 }
 112
 113 /*******************************************************************
 114  Get all share mode entries for a dev/inode pair.
 115 ********************************************************************/
 116
 117 static struct share_mode_data *parse_share_modes(TALLOC_CTX *mem_ctx,
 118                                                  const TDB_DATA dbuf)
 119 {
 120         struct share_mode_data *d;
 121         enum ndr_err_code ndr_err;
 122         DATA_BLOB blob;
 123
 124         d = talloc(mem_ctx, struct share_mode_data);
 125         if (d == NULL) {
 126                 DEBUG(0, ("talloc failed\n"));
 127                 goto fail;
 128         }
 129
 130         blob.data = dbuf.dptr;
 131         blob.length = dbuf.dsize;
 132
 133         ndr_err = ndr_pull_struct_blob(
 134                 &blob, d, d, (ndr_pull_flags_fn_t)ndr_pull_share_mode_data);
 135         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 136                 DEBUG(1, ("ndr_pull_share_mode_lock failed\n"));
 137                 goto fail;
 138         }
 139
 140         d->modified = false;
 141         d->fresh = false;
 142
 143         if (DEBUGLEVEL >= 10) {
 144                 DEBUG(10, ("parse_share_modes:\n"));
 145                 NDR_PRINT_DEBUG(share_mode_data, d);
 146         }
 147
 148         return d;
 149 fail:
 150         TALLOC_FREE(d);
 151         return NULL;
 152 }
 153
 154 /*******************************************************************
 155  Create a storable data blob from a modified share_mode_data struct.
 156 ********************************************************************/
 157
 158 static TDB_DATA unparse_share_modes(struct share_mode_data *d)
 159 {
 160         DATA_BLOB blob;
 161         enum ndr_err_code ndr_err;
 162
 163         if (DEBUGLEVEL >= 10) {
 164                 DEBUG(10, ("unparse_share_modes:\n"));
 165                 NDR_PRINT_DEBUG(share_mode_data, d);
 166         }
 167
 168         if (d->num_share_modes == 0) {
 169                 DEBUG(10, ("No used share mode found\n"));
 170                 return make_tdb_data(NULL, 0);
 171         }
 172
 173         ndr_err = ndr_push_struct_blob(
 174                 &blob, d, d, (ndr_push_flags_fn_t)ndr_push_share_mode_data);
 175         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 176                 smb_panic("ndr_push_share_mode_lock failed");
 177         }
 178
 179         return make_tdb_data(blob.data, blob.length);
 180 }
 181
 182 /*******************************************************************
 183  If modified, store the share_mode_data back into the database.
 184 ********************************************************************/
 185
 186 static int share_mode_data_destructor(struct share_mode_data *d)
 187 {
 188         NTSTATUS status;
 189         TDB_DATA data;
 190
 191         if (!d->modified) {
 192                 return 0;
 193         }
 194
 195         data = unparse_share_modes(d);
 196
 197         if (data.dptr == NULL) {
 198                 if (!d->fresh) {
 199                         /* There has been an entry before, delete it */
 200
 201                         status = dbwrap_record_delete(d->record);
 202                         if (!NT_STATUS_IS_OK(status)) {
 203                                 char *errmsg;
 204
 205                                 DEBUG(0, ("delete_rec returned %s\n",
 206                                           nt_errstr(status)));
 207
 208                                 if (asprintf(&errmsg, "could not delete share "
 209                                              "entry: %s\n",
 210                                              nt_errstr(status)) == -1) {
 211                                         smb_panic("could not delete share"
 212                                                   "entry");
 213                                 }
 214                                 smb_panic(errmsg);
 215                         }
 216                 }
 217                 goto done;
 218         }
 219
 220         status = dbwrap_record_store(d->record, data, TDB_REPLACE);
 221         if (!NT_STATUS_IS_OK(status)) {
 222                 char *errmsg;
 223
 224                 DEBUG(0, ("store returned %s\n", nt_errstr(status)));
 225
 226                 if (asprintf(&errmsg, "could not store share mode entry: %s",
 227                              nt_errstr(status)) == -1) {
 228                         smb_panic("could not store share mode entry");
 229                 }
 230                 smb_panic(errmsg);
 231         }
 232
 233  done:
 234
 235         return 0;
 236 }
 237
 238 /*******************************************************************
 239  Allocate a new share_mode_data struct, mark it unmodified.
 240  fresh is set to note that currently there is no database entry.
 241 ********************************************************************/
 242
 243 static struct share_mode_data *fresh_share_mode_lock(
 244         TALLOC_CTX *mem_ctx, const char *servicepath,
 245         const struct smb_filename *smb_fname,
 246         const struct timespec *old_write_time)
 247 {
 248         struct share_mode_data *d;
 249
 250         if ((servicepath == NULL) || (smb_fname == NULL) ||
 251             (old_write_time == NULL)) {
 252                 return NULL;
 253         }
 254
 255         d = talloc_zero(mem_ctx, struct share_mode_data);
 256         if (d == NULL) {
 257                 goto fail;
 258         }
 259         d->base_name = talloc_strdup(d, smb_fname->base_name);
 260         if (d->base_name == NULL) {
 261                 goto fail;
 262         }
 263         if (smb_fname->stream_name != NULL) {
 264                 d->stream_name = talloc_strdup(d, smb_fname->stream_name);
 265                 if (d->stream_name == NULL) {
 266                         goto fail;
 267                 }
 268         }
 269         d->servicepath = talloc_strdup(d, servicepath);
 270         if (d->servicepath == NULL) {
 271                 goto fail;
 272         }
 273         d->old_write_time = *old_write_time;
 274         d->modified = false;
 275         d->fresh = true;
 276         return d;
 277 fail:
 278         DEBUG(0, ("talloc failed\n"));
 279         TALLOC_FREE(d);
 280         return NULL;
 281 }
 282
 283 /*******************************************************************
 284  Either fetch a share mode from the database, or allocate a fresh
 285  one if the record doesn't exist.
 286 ********************************************************************/
 287
 288 static struct share_mode_lock *get_share_mode_lock_internal(
 289         TALLOC_CTX *mem_ctx, const struct file_id id,
 290         const char *servicepath, const struct smb_filename *smb_fname,
 291         const struct timespec *old_write_time)
 292 {
 293         struct share_mode_lock *lck;
 294         struct share_mode_data *d;
 295         struct file_id tmp;
 296         struct db_record *rec;
 297         TDB_DATA key = locking_key(&id, &tmp);
 298         TDB_DATA value;
 299
 300         rec = dbwrap_fetch_locked(lock_db, mem_ctx, key);
 301         if (rec == NULL) {
 302                 DEBUG(3, ("Could not lock share entry\n"));
 303                 return NULL;
 304         }
 305
 306         value = dbwrap_record_get_value(rec);
 307
 308         if (value.dptr == NULL) {
 309                 d = fresh_share_mode_lock(mem_ctx, servicepath, smb_fname,
 310                                           old_write_time);
 311         } else {
 312                 d = parse_share_modes(mem_ctx, value);
 313         }
 314
 315         if (d == NULL) {
 316                 DEBUG(5, ("get_share_mode_lock_internal: "
 317                         "Could not get share mode lock\n"));
 318                 TALLOC_FREE(rec);
 319                 return NULL;
 320         }
 321         d->id = id;
 322         d->record = talloc_move(d, &rec);
 323         talloc_set_destructor(d, share_mode_data_destructor);
 324
 325         lck = talloc(mem_ctx, struct share_mode_lock);
 326         if (lck == NULL) {
 327                 DEBUG(1, ("talloc failed\n"));
 328                 TALLOC_FREE(d);
 329                 return NULL;
 330         }
 331         lck->data = talloc_move(lck, &d);
 332         return lck;
 333 }
 334
 335 /*
 336  * We can only ever have one share mode locked. Users of
 337  * get_share_mode_lock never see this, it will be refcounted by
 338  * talloc_reference.
 339  */
 340 static struct share_mode_lock *the_lock;
 341
 342 static int the_lock_destructor(struct share_mode_lock *l)
 343 {
 344         the_lock = NULL;
 345         return 0;
 346 }
 347
 348 /*******************************************************************
 349  Get a share_mode_lock, Reference counted to allow nested calls.
 350 ********************************************************************/
 351
 352 struct share_mode_lock *get_share_mode_lock(
 353         TALLOC_CTX *mem_ctx,
 354         const struct file_id id,
 355         const char *servicepath,
 356         const struct smb_filename *smb_fname,
 357         const struct timespec *old_write_time)
 358 {
 359         TALLOC_CTX *frame = talloc_stackframe();
 360
 361         struct share_mode_lock *lck;
 362
 363         if (the_lock == NULL) {
 364                 the_lock = get_share_mode_lock_internal(
 365                         frame, id, servicepath, smb_fname, old_write_time);
 366                 if (the_lock == NULL) {
 367                         goto fail;
 368                 }
 369                 talloc_set_destructor(the_lock, the_lock_destructor);
 370         }
 371         if (!file_id_equal(&the_lock->data->id, &id)) {
 372                 DEBUG(1, ("Can not lock two share modes simultaneously\n"));
 373                 goto fail;
 374         }
 375         lck = talloc(mem_ctx, struct share_mode_lock);
 376         if (lck == NULL) {
 377                 DEBUG(1, ("talloc failed\n"));
 378                 goto fail;
 379         }
 380         if (talloc_reference(lck, the_lock) == NULL) {
 381                 DEBUG(1, ("talloc_reference failed\n"));
 382                 goto fail;
 383         }
 384         lck->data = the_lock->data;
 385         TALLOC_FREE(frame);
 386         return lck;
 387 fail:
 388         TALLOC_FREE(frame);
 389         return NULL;
 390 }
 391
 392 static void fetch_share_mode_unlocked_parser(
 393         TDB_DATA key, TDB_DATA data, void *private_data)
 394 {
 395         struct share_mode_lock *lck = talloc_get_type_abort(
 396                 private_data, struct share_mode_lock);
 397
 398         lck->data = parse_share_modes(lck, data);
 399 }
 400
 401 /*******************************************************************
 402  Get a share_mode_lock without locking the database or reference
 403  counting. Used by smbstatus to display existing share modes.
 404 ********************************************************************/
 405
 406 struct share_mode_lock *fetch_share_mode_unlocked(TALLOC_CTX *mem_ctx,
 407                                                   const struct file_id id)
 408 {
 409         struct share_mode_lock *lck;
 410         struct file_id tmp;
 411         TDB_DATA key = locking_key(&id, &tmp);
 412         NTSTATUS status;
 413
 414         lck = talloc(mem_ctx, struct share_mode_lock);
 415         if (lck == NULL) {
 416                 DEBUG(0, ("talloc failed\n"));
 417                 return NULL;
 418         }
 419         status = dbwrap_parse_record(
 420                 lock_db, key, fetch_share_mode_unlocked_parser, lck);
 421         if (!NT_STATUS_IS_OK(status) ||
 422             (lck->data == NULL)) {
 423                 TALLOC_FREE(lck);
 424                 return NULL;
 425         }
 426         return lck;
 427 }
 428
 429 struct forall_state {
 430         void (*fn)(const struct share_mode_entry *entry,
 431                    const char *sharepath,
 432                    const char *fname,
 433                    void *private_data);
 434         void *private_data;
 435 };
 436
 437 static int traverse_fn(struct db_record *rec, void *_state)
 438 {
 439         struct forall_state *state = (struct forall_state *)_state;
 440         uint32_t i;
 441         TDB_DATA key;
 442         TDB_DATA value;
 443         DATA_BLOB blob;
 444         enum ndr_err_code ndr_err;
 445         struct share_mode_data *d;
 446
 447         key = dbwrap_record_get_key(rec);
 448         value = dbwrap_record_get_value(rec);
 449
 450         /* Ensure this is a locking_key record. */
 451         if (key.dsize != sizeof(struct file_id))
 452                 return 0;
 453
 454         d = talloc(talloc_tos(), struct share_mode_data);
 455         if (d == NULL) {
 456                 return 0;
 457         }
 458
 459         blob.data = value.dptr;
 460         blob.length = value.dsize;
 461
 462         ndr_err = ndr_pull_struct_blob(
 463                 &blob, d, d, (ndr_pull_flags_fn_t)ndr_pull_share_mode_data);
 464         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 465                 DEBUG(1, ("ndr_pull_share_mode_lock failed\n"));
 466                 return 0;
 467         }
 468         for (i=0; i<d->num_share_modes; i++) {
 469                 state->fn(&d->share_modes[i],
 470                           d->servicepath, d->base_name,
 471                           state->private_data);
 472         }
 473         TALLOC_FREE(d);
 474
 475         return 0;
 476 }
 477
 478 /*******************************************************************
 479  Call the specified function on each entry under management by the
 480  share mode system.
 481 ********************************************************************/
 482
 483 int share_mode_forall(void (*fn)(const struct share_mode_entry *, const char *,
 484                                  const char *, void *),
 485                       void *private_data)
 486 {
 487         struct forall_state state;
 488         NTSTATUS status;
 489         int count;
 490
 491         if (lock_db == NULL)
 492                 return 0;
 493
 494         state.fn = fn;
 495         state.private_data = private_data;
 496
 497         status = dbwrap_traverse_read(lock_db, traverse_fn, (void *)&state,
 498                                       &count);
 499
 500         if (!NT_STATUS_IS_OK(status)) {
 501                 return -1;
 502         } else {
 503                 return count;
 504         }
 505 }