kern_fileassoc.c revision 1.16 
1/* $NetBSD: kern_fileassoc.c,v 1.16 2006/12/14 09:24:54 yamt Exp $ */
2
3/*-
4 * Copyright (c) 2006 Elad Efrat <elad@NetBSD.org>
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 * 3. All advertising materials mentioning features or use of this software
16 *    must display the following acknowledgement:
17 *      This product includes software developed by Elad Efrat.
18 * 4. The name of the author may not be used to endorse or promote products
19 *    derived from this software without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
22 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
23 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
24 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
25 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
26 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
27 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
28 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
29 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
30 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
31 */
32
33#include <sys/cdefs.h>
34__KERNEL_RCSID(0, "$NetBSD: kern_fileassoc.c,v 1.16 2006/12/14 09:24:54 yamt Exp $");
35
36#include "opt_fileassoc.h"
37
38#include <sys/param.h>
39#include <sys/mount.h>
40#include <sys/queue.h>
41#include <sys/malloc.h>
42#include <sys/vnode.h>
43#include <sys/namei.h>
44#include <sys/exec.h>
45#include <sys/proc.h>
46#include <sys/inttypes.h>
47#include <sys/errno.h>
48#include <sys/fileassoc.h>
49#include <sys/specificdata.h>
50#include <sys/hash.h>
51#include <sys/fstypes.h>
52#include <sys/kmem.h>
53#include <sys/once.h>
54
55static struct fileassoc_hash_entry *
56fileassoc_file_lookup(struct vnode *, fhandle_t *);
57static struct fileassoc_hash_entry *
58fileassoc_file_add(struct vnode *, fhandle_t *);
59
60static specificdata_domain_t fileassoc_domain;
61static specificdata_key_t fileassoc_mountspecific_key;
62
63/*
64 * Hook entry.
65 * Includes the hook name for identification and private hook clear callback.
66 */
67struct fileassoc {
68	LIST_ENTRY(fileassoc) list;
69	const char *name;			/* name. */
70	fileassoc_cleanup_cb_t cleanup_cb;	/* clear callback. */
71	specificdata_key_t key;
72};
73
74static LIST_HEAD(, fileassoc) fileassoc_list;
75
76/* An entry in the per-device hash table. */
77struct fileassoc_hash_entry {
78	fhandle_t *handle;				/* File handle */
79	specificdata_reference data;			/* Hooks. */
80	LIST_ENTRY(fileassoc_hash_entry) entries;	/* List pointer. */
81};
82
83LIST_HEAD(fileassoc_hashhead, fileassoc_hash_entry);
84
85struct fileassoc_table {
86	struct fileassoc_hashhead *hash_tbl;
87	size_t hash_size;				/* Number of slots. */
88	u_long hash_mask;
89	specificdata_reference data;
90};
91
92/*
93 * Hashing function: Takes a number modulus the mask to give back an
94 * index into the hash table.
95 */
96#define FILEASSOC_HASH(tbl, handle)	\
97	(hash32_buf((handle), FHANDLE_SIZE(handle), HASH32_BUF_INIT) \
98	 & ((tbl)->hash_mask))
99
100static void *
101table_getdata(struct fileassoc_table *tbl, const struct fileassoc *assoc)
102{
103
104	return specificdata_getspecific(fileassoc_domain, &tbl->data,
105	    assoc->key);
106}
107
108static void
109table_setdata(struct fileassoc_table *tbl, const struct fileassoc *assoc,
110    void *data)
111{
112
113	specificdata_setspecific(fileassoc_domain, &tbl->data, assoc->key,
114	    data);
115}
116
117static void
118table_cleanup(struct fileassoc_table *tbl, const struct fileassoc *assoc)
119{
120	fileassoc_cleanup_cb_t cb;
121	void *data;
122
123	cb = assoc->cleanup_cb;
124	if (cb == NULL) {
125		return;
126	}
127	data = table_getdata(tbl, assoc);
128	(*cb)(data, FILEASSOC_CLEANUP_TABLE);
129}
130
131static void *
132file_getdata(struct fileassoc_hash_entry *e, const struct fileassoc *assoc)
133{
134
135	return specificdata_getspecific(fileassoc_domain, &e->data,
136	    assoc->key);
137}
138
139static void
140file_setdata(struct fileassoc_hash_entry *e, const struct fileassoc *assoc,
141    void *data)
142{
143
144	specificdata_setspecific(fileassoc_domain, &e->data, assoc->key,
145	    data);
146}
147
148static void
149file_cleanup(struct fileassoc_hash_entry *e, const struct fileassoc *assoc)
150{
151	fileassoc_cleanup_cb_t cb;
152	void *data;
153
154	cb = assoc->cleanup_cb;
155	if (cb == NULL) {
156		return;
157	}
158	data = file_getdata(e, assoc);
159	(*cb)(data, FILEASSOC_CLEANUP_FILE);
160}
161
162static void
163file_free(struct fileassoc_hash_entry *e)
164{
165	struct fileassoc *assoc;
166
167	LIST_REMOVE(e, entries);
168
169	LIST_FOREACH(assoc, &fileassoc_list, list) {
170		file_cleanup(e, assoc);
171	}
172	vfs_composefh_free(e->handle);
173	specificdata_fini(fileassoc_domain, &e->data);
174	kmem_free(e, sizeof(*e));
175}
176
177static void
178table_dtor(void *vp)
179{
180	struct fileassoc_table *tbl = vp;
181	const struct fileassoc *assoc;
182	struct fileassoc_hashhead *hh;
183	u_long i;
184
185	/* Remove all entries from the table and lists */
186	hh = tbl->hash_tbl;
187	for (i = 0; i < tbl->hash_size; i++) {
188		struct fileassoc_hash_entry *mhe;
189
190		while ((mhe = LIST_FIRST(&hh[i])) != NULL) {
191			file_free(mhe);
192		}
193	}
194
195	LIST_FOREACH(assoc, &fileassoc_list, list) {
196		table_cleanup(tbl, assoc);
197	}
198
199	/* Remove hash table and sysctl node */
200	hashdone(tbl->hash_tbl, M_TEMP);
201	specificdata_fini(fileassoc_domain, &tbl->data);
202	kmem_free(tbl, sizeof(*tbl));
203}
204
205/*
206 * Initialize the fileassoc subsystem.
207 */
208static int
209fileassoc_init(void)
210{
211	int error;
212
213	error = mount_specific_key_create(&fileassoc_mountspecific_key,
214	    table_dtor);
215	if (error) {
216		return error;
217	}
218	fileassoc_domain = specificdata_domain_create();
219
220	return 0;
221}
222
223/*
224 * Register a new hook.
225 */
226int
227fileassoc_register(const char *name, fileassoc_cleanup_cb_t cleanup_cb,
228    fileassoc_t *result)
229{
230	int error;
231	specificdata_key_t key;
232	struct fileassoc *assoc;
233	static ONCE_DECL(control);
234
235	error = RUN_ONCE(&control, fileassoc_init);
236	if (error) {
237		return error;
238	}
239	error = specificdata_key_create(fileassoc_domain, &key, NULL);
240	if (error) {
241		return error;
242	}
243	assoc = kmem_alloc(sizeof(*assoc), KM_SLEEP);
244	assoc->name = name;
245	assoc->cleanup_cb = cleanup_cb;
246	assoc->key = key;
247	LIST_INSERT_HEAD(&fileassoc_list, assoc, list);
248	*result = assoc;
249
250	return 0;
251}
252
253/*
254 * Deregister a hook.
255 */
256int
257fileassoc_deregister(fileassoc_t assoc)
258{
259
260	LIST_REMOVE(assoc, list);
261	kmem_free(assoc, sizeof(*assoc));
262
263	return 0;
264}
265
266/*
267 * Get the hash table for the specified device.
268 */
269static struct fileassoc_table *
270fileassoc_table_lookup(struct mount *mp)
271{
272
273	return mount_getspecific(mp, fileassoc_mountspecific_key);
274}
275
276/*
277 * Perform a lookup on a hash table.  If hint is non-zero then use the value
278 * of the hint as the identifier instead of performing a lookup for the
279 * fileid.
280 */
281static struct fileassoc_hash_entry *
282fileassoc_file_lookup(struct vnode *vp, fhandle_t *hint)
283{
284	struct fileassoc_table *tbl;
285	struct fileassoc_hashhead *tble;
286	struct fileassoc_hash_entry *e;
287	size_t indx;
288	fhandle_t *th;
289	int error;
290
291	tbl = fileassoc_table_lookup(vp->v_mount);
292	if (tbl == NULL) {
293		return NULL;
294	}
295
296	if (hint == NULL) {
297		error = vfs_composefh_alloc(vp, &th);
298		if (error)
299			return (NULL);
300	} else {
301		th = hint;
302	}
303
304	indx = FILEASSOC_HASH(tbl, th);
305	tble = &(tbl->hash_tbl[indx]);
306
307	LIST_FOREACH(e, tble, entries) {
308		if (((FHANDLE_FILEID(e->handle)->fid_len ==
309		     FHANDLE_FILEID(th)->fid_len)) &&
310		    (memcmp(FHANDLE_FILEID(e->handle), FHANDLE_FILEID(th),
311			   (FHANDLE_FILEID(th))->fid_len) == 0)) {
312			break;
313		}
314	}
315
316	if (hint == NULL)
317		vfs_composefh_free(th);
318
319	return e;
320}
321
322/*
323 * Return hook data associated with a vnode.
324 */
325void *
326fileassoc_lookup(struct vnode *vp, fileassoc_t assoc)
327{
328        struct fileassoc_hash_entry *mhe;
329
330        mhe = fileassoc_file_lookup(vp, NULL);
331        if (mhe == NULL)
332                return (NULL);
333
334        return file_getdata(mhe, assoc);
335}
336
337/*
338 * Create a new fileassoc table.
339 */
340int
341fileassoc_table_add(struct mount *mp, size_t size)
342{
343	struct fileassoc_table *tbl;
344
345	/* Check for existing table for device. */
346	if (fileassoc_table_lookup(mp) != NULL)
347		return (EEXIST);
348
349	/* Allocate and initialize a Veriexec hash table. */
350	tbl = kmem_zalloc(sizeof(*tbl), KM_SLEEP);
351	tbl->hash_size = size;
352	tbl->hash_tbl = hashinit(size, HASH_LIST, M_TEMP,
353				 M_WAITOK | M_ZERO, &tbl->hash_mask);
354	specificdata_init(fileassoc_domain, &tbl->data);
355
356	mount_setspecific(mp, fileassoc_mountspecific_key, tbl);
357
358	return (0);
359}
360
361/*
362 * Delete a table.
363 */
364int
365fileassoc_table_delete(struct mount *mp)
366{
367	struct fileassoc_table *tbl;
368
369	tbl = fileassoc_table_lookup(mp);
370	if (tbl == NULL)
371		return (EEXIST);
372
373	mount_setspecific(mp, fileassoc_mountspecific_key, NULL);
374	table_dtor(tbl);
375
376	return (0);
377}
378
379/*
380 * Run a callback for each hook entry in a table.
381 */
382int
383fileassoc_table_run(struct mount *mp, fileassoc_t assoc, fileassoc_cb_t cb)
384{
385	struct fileassoc_table *tbl;
386	struct fileassoc_hashhead *hh;
387	u_long i;
388
389	tbl = fileassoc_table_lookup(mp);
390	if (tbl == NULL)
391		return (EEXIST);
392
393	hh = tbl->hash_tbl;
394	for (i = 0; i < tbl->hash_size; i++) {
395		struct fileassoc_hash_entry *mhe;
396
397		LIST_FOREACH(mhe, &hh[i], entries) {
398			void *data;
399
400			data = file_getdata(mhe, assoc);
401			if (data != NULL)
402				cb(data);
403		}
404	}
405
406	return (0);
407}
408
409/*
410 * Clear a table for a given hook.
411 */
412int
413fileassoc_table_clear(struct mount *mp, fileassoc_t assoc)
414{
415	struct fileassoc_table *tbl;
416	struct fileassoc_hashhead *hh;
417	u_long i;
418
419	tbl = fileassoc_table_lookup(mp);
420	if (tbl == NULL)
421		return (EEXIST);
422
423	hh = tbl->hash_tbl;
424	for (i = 0; i < tbl->hash_size; i++) {
425		struct fileassoc_hash_entry *mhe;
426
427		LIST_FOREACH(mhe, &hh[i], entries) {
428			file_cleanup(mhe, assoc);
429			file_setdata(mhe, assoc, NULL);
430		}
431	}
432
433	table_cleanup(tbl, assoc);
434	table_setdata(tbl, assoc, NULL);
435
436	return (0);
437}
438
439/*
440 * Add hook-specific data on a fileassoc table.
441 */
442int
443fileassoc_tabledata_add(struct mount *mp, fileassoc_t assoc, void *data)
444{
445	struct fileassoc_table *tbl;
446
447	tbl = fileassoc_table_lookup(mp);
448	if (tbl == NULL)
449		return (EFAULT);
450
451	table_setdata(tbl, assoc, data);
452
453	return (0);
454}
455
456/*
457 * Clear hook-specific data on a fileassoc table.
458 */
459int
460fileassoc_tabledata_clear(struct mount *mp, fileassoc_t assoc)
461{
462
463	return fileassoc_tabledata_add(mp, assoc, NULL);
464}
465
466/*
467 * Retrieve hook-specific data from a fileassoc table.
468 */
469void *
470fileassoc_tabledata_lookup(struct mount *mp, fileassoc_t assoc)
471{
472	struct fileassoc_table *tbl;
473
474	tbl = fileassoc_table_lookup(mp);
475	if (tbl == NULL)
476		return (NULL);
477
478	return table_getdata(tbl, assoc);
479}
480
481/*
482 * Add a file entry to a table.
483 */
484static struct fileassoc_hash_entry *
485fileassoc_file_add(struct vnode *vp, fhandle_t *hint)
486{
487	struct fileassoc_table *tbl;
488	struct fileassoc_hashhead *vhh;
489	struct fileassoc_hash_entry *e;
490	size_t indx;
491	fhandle_t *th;
492	int error;
493
494	if (hint == NULL) {
495		error = vfs_composefh_alloc(vp, &th);
496		if (error)
497			return (NULL);
498	} else
499		th = hint;
500
501	e = fileassoc_file_lookup(vp, th);
502	if (e != NULL) {
503		if (hint == NULL)
504			vfs_composefh_free(th);
505
506		return (e);
507	}
508
509	tbl = fileassoc_table_lookup(vp->v_mount);
510	if (tbl == NULL) {
511		if (hint == NULL)
512			vfs_composefh_free(th);
513
514		return (NULL);
515	}
516
517	indx = FILEASSOC_HASH(tbl, th);
518	vhh = &(tbl->hash_tbl[indx]);
519
520	e = kmem_zalloc(sizeof(*e), KM_SLEEP);
521	e->handle = th;
522	specificdata_init(fileassoc_domain, &e->data);
523	LIST_INSERT_HEAD(vhh, e, entries);
524
525	return (e);
526}
527
528/*
529 * Delete a file entry from a table.
530 */
531int
532fileassoc_file_delete(struct vnode *vp)
533{
534	struct fileassoc_hash_entry *mhe;
535
536	mhe = fileassoc_file_lookup(vp, NULL);
537	if (mhe == NULL)
538		return (ENOENT);
539
540	file_free(mhe);
541
542	return (0);
543}
544
545/*
546 * Add a hook to a vnode.
547 */
548int
549fileassoc_add(struct vnode *vp, fileassoc_t assoc, void *data)
550{
551	struct fileassoc_hash_entry *e;
552	void *olddata;
553
554	e = fileassoc_file_lookup(vp, NULL);
555	if (e == NULL) {
556		e = fileassoc_file_add(vp, NULL);
557		if (e == NULL)
558			return (ENOTDIR);
559	}
560
561	olddata = file_getdata(e, assoc);
562	if (olddata != NULL)
563		return (EEXIST);
564
565	file_setdata(e, assoc, data);
566
567	return (0);
568}
569
570/*
571 * Clear a hook from a vnode.
572 */
573int
574fileassoc_clear(struct vnode *vp, fileassoc_t assoc)
575{
576	struct fileassoc_hash_entry *mhe;
577
578	mhe = fileassoc_file_lookup(vp, NULL);
579	if (mhe == NULL)
580		return (ENOENT);
581
582	file_cleanup(mhe, assoc);
583	file_setdata(mhe, assoc, NULL);
584
585	return (0);
586}
587