summaryrefslogtreecommitdiff
path: root/source3/locking/share_mode_lock.c
blob: 1fea748e724f3a0358b641ae6a8c836036c99a66 (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
/*
   Unix SMB/CIFS implementation.
   Locking functions
   Copyright (C) Andrew Tridgell 1992-2000
   Copyright (C) Jeremy Allison 1992-2006
   Copyright (C) Volker Lendecke 2005

   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; either version 3 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/>.

   Revision History:

   12 aug 96: Erik.Devriendt@te6.siemens.be
   added support for shared memory implementation of share mode locking

   May 1997. Jeremy Allison (jallison@whistle.com). Modified share mode
   locking to deal with multiple share modes per open file.

   September 1997. Jeremy Allison (jallison@whistle.com). Added oplock
   support.

   rewritten completely to use new tdb code. Tridge, Dec '99

   Added POSIX locking support. Jeremy Allison (jeremy@valinux.com), Apr. 2000.
   Added Unix Extensions POSIX locking support. Jeremy Allison Mar 2006.
*/

#include "includes.h"
#include "system/filesys.h"
#include "locking/proto.h"
#include "smbd/globals.h"
#include "dbwrap/dbwrap.h"
#include "dbwrap/dbwrap_open.h"
#include "../libcli/security/security.h"
#include "serverid.h"
#include "messages.h"
#include "util_tdb.h"
#include "../librpc/gen_ndr/ndr_open_files.h"

#undef DBGC_CLASS
#define DBGC_CLASS DBGC_LOCKING

#define NO_LOCKING_COUNT (-1)

/* the locking database handle */
static struct db_context *lock_db;

static bool locking_init_internal(bool read_only)
{
	brl_init(read_only);

	if (lock_db)
		return True;

	lock_db = db_open(NULL, lock_path("locking.tdb"),
			  lp_open_files_db_hash_size(),
			  TDB_DEFAULT|TDB_VOLATILE|TDB_CLEAR_IF_FIRST|TDB_INCOMPATIBLE_HASH,
			  read_only?O_RDONLY:O_RDWR|O_CREAT, 0644,
			  DBWRAP_LOCK_ORDER_1);

	if (!lock_db) {
		DEBUG(0,("ERROR: Failed to initialise locking database\n"));
		return False;
	}

	if (!posix_locking_init(read_only))
		return False;

	return True;
}

bool locking_init(void)
{
	return locking_init_internal(false);
}

bool locking_init_readonly(void)
{
	return locking_init_internal(true);
}

/*******************************************************************
 Deinitialize the share_mode management.
******************************************************************/

bool locking_end(void)
{
	brl_shutdown();
	TALLOC_FREE(lock_db);
	return true;
}

/*******************************************************************
 Form a static locking key for a dev/inode pair.
******************************************************************/

static TDB_DATA locking_key(const struct file_id *id, struct file_id *tmp)
{
	*tmp = *id;
	return make_tdb_data((const uint8_t *)tmp, sizeof(*tmp));
}

/*******************************************************************
 Get all share mode entries for a dev/inode pair.
********************************************************************/

static struct share_mode_data *parse_share_modes(TALLOC_CTX *mem_ctx,
						 const TDB_DATA dbuf)
{
	struct share_mode_data *d;
	enum ndr_err_code ndr_err;
	DATA_BLOB blob;

	d = talloc(mem_ctx, struct share_mode_data);
	if (d == NULL) {
		DEBUG(0, ("talloc failed\n"));
		goto fail;
	}

	blob.data = dbuf.dptr;
	blob.length = dbuf.dsize;

	ndr_err = ndr_pull_struct_blob(
		&blob, d, d, (ndr_pull_flags_fn_t)ndr_pull_share_mode_data);
	if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
		DEBUG(1, ("ndr_pull_share_mode_lock failed\n"));
		goto fail;
	}

	d->modified = false;
	d->fresh = false;

	if (DEBUGLEVEL >= 10) {
		DEBUG(10, ("parse_share_modes:\n"));
		NDR_PRINT_DEBUG(share_mode_data, d);
	}

	return d;
fail:
	TALLOC_FREE(d);
	return NULL;
}

/*******************************************************************
 Create a storable data blob from a modified share_mode_data struct.
********************************************************************/

static TDB_DATA unparse_share_modes(struct share_mode_data *d)
{
	DATA_BLOB blob;
	enum ndr_err_code ndr_err;

	if (DEBUGLEVEL >= 10) {
		DEBUG(10, ("unparse_share_modes:\n"));
		NDR_PRINT_DEBUG(share_mode_data, d);
	}

	if (d->num_share_modes == 0) {
		DEBUG(10, ("No used share mode found\n"));
		return make_tdb_data(NULL, 0);
	}

	ndr_err = ndr_push_struct_blob(
		&blob, d, d, (ndr_push_flags_fn_t)ndr_push_share_mode_data);
	if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
		smb_panic("ndr_push_share_mode_lock failed");
	}

	return make_tdb_data(blob.data, blob.length);
}

/*******************************************************************
 If modified, store the share_mode_data back into the database.
********************************************************************/

static int share_mode_data_destructor(struct share_mode_data *d)
{
	NTSTATUS status;
	TDB_DATA data;

	if (!d->modified) {
		return 0;
	}

	data = unparse_share_modes(d);

	if (data.dptr == NULL) {
		if (!d->fresh) {
			/* There has been an entry before, delete it */

			status = dbwrap_record_delete(d->record);
			if (!NT_STATUS_IS_OK(status)) {
				char *errmsg;

				DEBUG(0, ("delete_rec returned %s\n",
					  nt_errstr(status)));

				if (asprintf(&errmsg, "could not delete share "
					     "entry: %s\n",
					     nt_errstr(status)) == -1) {
					smb_panic("could not delete share"
						  "entry");
				}
				smb_panic(errmsg);
			}
		}
		goto done;
	}

	status = dbwrap_record_store(d->record, data, TDB_REPLACE);
	if (!NT_STATUS_IS_OK(status)) {
		char *errmsg;

		DEBUG(0, ("store returned %s\n", nt_errstr(status)));

		if (asprintf(&errmsg, "could not store share mode entry: %s",
			     nt_errstr(status)) == -1) {
			smb_panic("could not store share mode entry");
		}
		smb_panic(errmsg);
	}

 done:

	return 0;
}

/*******************************************************************
 Allocate a new share_mode_data struct, mark it unmodified.
 fresh is set to note that currently there is no database entry.
********************************************************************/

static struct share_mode_data *fresh_share_mode_lock(
	TALLOC_CTX *mem_ctx, const char *servicepath,
	const struct smb_filename *smb_fname,
	const struct timespec *old_write_time)
{
	struct share_mode_data *d;

	if ((servicepath == NULL) || (smb_fname == NULL) ||
	    (old_write_time == NULL)) {
		return NULL;
	}

	d = talloc_zero(mem_ctx, struct share_mode_data);
	if (d == NULL) {
		goto fail;
	}
	d->base_name = talloc_strdup(d, smb_fname->base_name);
	if (d->base_name == NULL) {
		goto fail;
	}
	if (smb_fname->stream_name != NULL) {
		d->stream_name = talloc_strdup(d, smb_fname->stream_name);
		if (d->stream_name == NULL) {
			goto fail;
		}
	}
	d->servicepath = talloc_strdup(d, servicepath);
	if (d->servicepath == NULL) {
		goto fail;
	}
	d->old_write_time = *old_write_time;
	d->modified = false;
	d->fresh = true;
	return d;
fail:
	DEBUG(0, ("talloc failed\n"));
	TALLOC_FREE(d);
	return NULL;
}

/*******************************************************************
 Either fetch a share mode from the database, or allocate a fresh
 one if the record doesn't exist.
********************************************************************/

static struct share_mode_lock *get_share_mode_lock_internal(
	TALLOC_CTX *mem_ctx, const struct file_id id,
	const char *servicepath, const struct smb_filename *smb_fname,
	const struct timespec *old_write_time)
{
	struct share_mode_lock *lck;
	struct share_mode_data *d;
	struct file_id tmp;
	struct db_record *rec;
	TDB_DATA key = locking_key(&id, &tmp);
	TDB_DATA value;

	rec = dbwrap_fetch_locked(lock_db, mem_ctx, key);
	if (rec == NULL) {
		DEBUG(3, ("Could not lock share entry\n"));
		return NULL;
	}

	value = dbwrap_record_get_value(rec);

	if (value.dptr == NULL) {
		d = fresh_share_mode_lock(mem_ctx, servicepath, smb_fname,
					  old_write_time);
	} else {
		d = parse_share_modes(mem_ctx, value);
	}

	if (d == NULL) {
		DEBUG(1, ("Could not get share mode lock\n"));
		TALLOC_FREE(rec);
		return NULL;
	}
	d->id = id;
	d->record = talloc_move(d, &rec);
	talloc_set_destructor(d, share_mode_data_destructor);

	lck = talloc(mem_ctx, struct share_mode_lock);
	if (lck == NULL) {
		DEBUG(1, ("talloc failed\n"));
		TALLOC_FREE(d);
		return NULL;
	}
	lck->data = talloc_move(lck, &d);
	return lck;
}

/*
 * We can only ever have one share mode locked. Users of
 * get_share_mode_lock never see this, it will be refcounted by
 * talloc_reference.
 */
static struct share_mode_lock *the_lock;

static int the_lock_destructor(struct share_mode_lock *l)
{
	the_lock = NULL;
	return 0;
}

/*******************************************************************
 Get a share_mode_lock, Reference counted to allow nexted calls.
********************************************************************/

struct share_mode_lock *get_share_mode_lock(
	TALLOC_CTX *mem_ctx,
	const struct file_id id,
	const char *servicepath,
	const struct smb_filename *smb_fname,
	const struct timespec *old_write_time)
{
	TALLOC_CTX *frame = talloc_stackframe();

	struct share_mode_lock *lck;

	if (the_lock == NULL) {
		the_lock = get_share_mode_lock_internal(
			frame, id, servicepath, smb_fname, old_write_time);
		if (the_lock == NULL) {
			goto fail;
		}
		talloc_set_destructor(the_lock, the_lock_destructor);
	}
	if (!file_id_equal(&the_lock->data->id, &id)) {
		DEBUG(1, ("Can not lock two share modes simultaneously\n"));
		goto fail;
	}
	lck = talloc(mem_ctx, struct share_mode_lock);
	if (lck == NULL) {
		DEBUG(1, ("talloc failed\n"));
		goto fail;
	}
	if (talloc_reference(lck, the_lock) == NULL) {
		DEBUG(1, ("talloc_reference failed\n"));
		goto fail;
	}
	lck->data = the_lock->data;
	TALLOC_FREE(frame);
	return lck;
fail:
	TALLOC_FREE(frame);
	return NULL;
}

/*******************************************************************
 Get a share_mode_lock without locking the database or reference
 counting. Used by smbstatus to display existing share modes.
********************************************************************/

struct share_mode_lock *fetch_share_mode_unlocked(TALLOC_CTX *mem_ctx,
						  const struct file_id id)
{
	struct share_mode_lock *lck;
	struct file_id tmp;
	TDB_DATA key = locking_key(&id, &tmp);
	TDB_DATA data;
	NTSTATUS status;

	status = dbwrap_fetch(lock_db, talloc_tos(), key, &data);
	if (!NT_STATUS_IS_OK(status)) {
		DEBUG(3, ("Could not fetch share entry\n"));
		return NULL;
	}
	if (data.dptr == NULL) {
		return NULL;
	}
	lck = talloc(mem_ctx, struct share_mode_lock);
	if (lck == NULL) {
		TALLOC_FREE(data.dptr);
		return NULL;
	}
	lck->data = parse_share_modes(lck, data);
	TALLOC_FREE(data.dptr);
	if (lck->data == NULL) {
		TALLOC_FREE(lck);
		return NULL;
	}
	return lck;
}

struct forall_state {
	void (*fn)(const struct share_mode_entry *entry,
		   const char *sharepath,
		   const char *fname,
		   void *private_data);
	void *private_data;
};

static int traverse_fn(struct db_record *rec, void *_state)
{
	struct forall_state *state = (struct forall_state *)_state;
	uint32_t i;
	TDB_DATA key;
	TDB_DATA value;
	DATA_BLOB blob;
	enum ndr_err_code ndr_err;
	struct share_mode_data *d;

	key = dbwrap_record_get_key(rec);
	value = dbwrap_record_get_value(rec);

	/* Ensure this is a locking_key record. */
	if (key.dsize != sizeof(struct file_id))
		return 0;

	d = talloc(talloc_tos(), struct share_mode_data);
	if (d == NULL) {
		return 0;
	}

	blob.data = value.dptr;
	blob.length = value.dsize;

	ndr_err = ndr_pull_struct_blob(
		&blob, d, d, (ndr_pull_flags_fn_t)ndr_pull_share_mode_data);
	if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
		DEBUG(1, ("ndr_pull_share_mode_lock failed\n"));
		return 0;
	}
	for (i=0; i<d->num_share_modes; i++) {
		state->fn(&d->share_modes[i],
			  d->servicepath, d->base_name,
			  state->private_data);
	}
	TALLOC_FREE(d);

	return 0;
}

/*******************************************************************
 Call the specified function on each entry under management by the
 share mode system.
********************************************************************/

int share_mode_forall(void (*fn)(const struct share_mode_entry *, const char *,
				 const char *, void *),
		      void *private_data)
{
	struct forall_state state;
	NTSTATUS status;
	int count;

	if (lock_db == NULL)
		return 0;

	state.fn = fn;
	state.private_data = private_data;

	status = dbwrap_traverse_read(lock_db, traverse_fn, (void *)&state,
				      &count);

	if (!NT_STATUS_IS_OK(status)) {
		return -1;
	} else {
		return count;
	}
}