kern_fileassoc.c revision 1.7 
1/* $NetBSD: kern_fileassoc.c,v 1.7 2006/08/13 06:21:10 xtraeme 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 1.7 2006/08/13 06:21:10 xtraeme Exp $");
35
36#include <sys/param.h>
37#include <sys/mount.h>
38#include <sys/queue.h>
39#include <sys/malloc.h>
40#include <sys/vnode.h>
41#include <sys/namei.h>
42#include <sys/exec.h>
43#include <sys/proc.h>
44#include <sys/inttypes.h>
45#include <sys/errno.h>
46#include <sys/fileassoc.h>
47#include <sys/hash.h>
48
49/*
50 * Hook entry.
51 * Includes the hook name for identification and private hook clear callback.
52 */
53struct fileassoc_hook {
54	const char *hook_name;			/* Hook name. */
55	fileassoc_cleanup_cb_t hook_cleanup_cb;	/* Hook clear callback. */
56};
57
58/* An entry in the per-device hash table. */
59struct fileassoc_hash_entry {
60	ino_t fileid;					/* File id. */
61	void *hooks[FILEASSOC_NHOOKS];			/* Hooks. */
62	LIST_ENTRY(fileassoc_hash_entry) entries;	/* List pointer. */
63};
64
65LIST_HEAD(fileassoc_hashhead, fileassoc_hash_entry);
66
67struct fileassoc_table {
68	struct fileassoc_hashhead *hash_tbl;
69	size_t hash_size;				/* Number of slots. */
70	struct mount *tbl_mntpt;
71	u_long hash_mask;
72	void *tables[FILEASSOC_NHOOKS];
73	LIST_ENTRY(fileassoc_table) hash_list;		/* List pointer. */
74};
75
76struct fileassoc_hook fileassoc_hooks[FILEASSOC_NHOOKS];
77int fileassoc_nhooks;
78
79/* Global list of hash tables, one per device. */
80LIST_HEAD(, fileassoc_table) fileassoc_tables;
81
82/*
83 * Hashing function: Takes a number modulus the mask to give back
84 * an index into the hash table.
85 */
86#define FILEASSOC_HASH(tbl, fileid)	\
87	(hash32_buf(&(fileid), sizeof((fileid)), HASH32_BUF_INIT) \
88	 & ((tbl)->hash_mask))
89
90/*
91 * Initialize the fileassoc subsystem.
92 */
93void
94fileassoc_init(void)
95{
96	memset(fileassoc_hooks, 0, sizeof(fileassoc_hooks));
97	fileassoc_nhooks = 0;
98}
99
100/*
101 * Register a new hook.
102 */
103fileassoc_t
104fileassoc_register(const char *name, fileassoc_cleanup_cb_t cleanup_cb)
105{
106	int i;
107
108	if (fileassoc_nhooks >= FILEASSOC_NHOOKS)
109		return (-1);
110
111	for (i = 0; i < FILEASSOC_NHOOKS; i++)
112		if (fileassoc_hooks[i].hook_name == NULL)
113			break;
114
115	fileassoc_hooks[i].hook_name = name;
116	fileassoc_hooks[i].hook_cleanup_cb = cleanup_cb;
117
118	fileassoc_nhooks++;
119
120	return (i);
121}
122
123/*
124 * Deregister a hook.
125 */
126int
127fileassoc_deregister(fileassoc_t id)
128{
129	if (id < 0 || id >= FILEASSOC_NHOOKS)
130		return (EINVAL);
131
132	fileassoc_hooks[id].hook_name = NULL;
133	fileassoc_hooks[id].hook_cleanup_cb = NULL;
134
135	fileassoc_nhooks--;
136
137	return (0);
138}
139
140/*
141 * Get the hash table for the specified device.
142 */
143static struct fileassoc_table *
144fileassoc_table_lookup(struct mount *mp)
145{
146	struct fileassoc_table *tbl;
147
148	LIST_FOREACH(tbl, &fileassoc_tables, hash_list) {
149		if (tbl->tbl_mntpt == mp)
150			return (tbl);
151	}
152
153	return (NULL);
154}
155
156/*
157 * Perform a lookup on a hash table.
158 */
159static struct fileassoc_hash_entry *
160fileassoc_file_lookup(struct vnode *vp)
161{
162	struct fileassoc_table *tbl;
163	struct fileassoc_hashhead *tble;
164	struct fileassoc_hash_entry *e;
165	struct vattr va;
166	size_t indx;
167	int error;
168
169	error = VOP_GETATTR(vp, &va, curlwp->l_cred, curlwp);
170	if (error)
171		return (NULL);
172
173	tbl = fileassoc_table_lookup(vp->v_mount);
174	if (tbl == NULL)
175		return (NULL);
176
177	/*
178	 * XXX: We should NOT rely on fileid here!
179	 */
180	indx = FILEASSOC_HASH(tbl, va.va_fileid);
181	tble = &(tbl->hash_tbl[indx & ((tbl)->hash_mask)]);
182
183	LIST_FOREACH(e, tble, entries) {
184		if ((e != NULL) && (e->fileid == va.va_fileid))
185			return (e);
186	}
187
188	return (NULL);
189}
190
191/*
192 * Return hook data associated with a vnode.
193 */
194void *
195fileassoc_lookup(struct vnode *vp, fileassoc_t id)
196{
197	struct fileassoc_hash_entry *mhe;
198
199	mhe = fileassoc_file_lookup(vp);
200	if (mhe == NULL)
201		return (NULL);
202
203	return (mhe->hooks[id]);
204}
205
206/*
207 * Create a new fileassoc table.
208 */
209int
210fileassoc_table_add(struct mount *mp, size_t size)
211{
212	struct fileassoc_table *tbl;
213
214	/* Check for existing table for device. */
215	if (fileassoc_table_lookup(mp) != NULL)
216		return (EEXIST);
217
218	/* Allocate and initialize a Veriexec hash table. */
219	tbl = malloc(sizeof(*tbl), M_TEMP, M_WAITOK | M_ZERO);
220	tbl->hash_size = size;
221	tbl->tbl_mntpt = mp;
222	tbl->hash_tbl = hashinit(size, HASH_LIST, M_TEMP,
223				 M_WAITOK | M_ZERO, &tbl->hash_mask);
224
225	LIST_INSERT_HEAD(&fileassoc_tables, tbl, hash_list);
226
227	return (0);
228}
229
230/*
231 * Delete a table.
232 */
233int
234fileassoc_table_delete(struct mount *mp)
235{
236	struct fileassoc_table *tbl;
237	struct fileassoc_hashhead *hh;
238	u_long i;
239	int j;
240
241	tbl = fileassoc_table_lookup(mp);
242	if (tbl == NULL)
243		return (EEXIST);
244
245	/* Remove all entries from the table and lists */
246	hh = tbl->hash_tbl;
247	for (i = 0; i < tbl->hash_size; i++) {
248		struct fileassoc_hash_entry *mhe;
249
250		while (LIST_FIRST(&hh[i]) != NULL) {
251			mhe = LIST_FIRST(&hh[i]);
252			LIST_REMOVE(mhe, entries);
253
254			for (j = 0; j < fileassoc_nhooks; j++)
255				if (fileassoc_hooks[j].hook_cleanup_cb != NULL)
256					(fileassoc_hooks[j].hook_cleanup_cb)
257					    (mhe->hooks[j],
258					    FILEASSOC_CLEANUP_FILE);
259
260			free(mhe, M_TEMP);
261		}
262	}
263
264	for (j = 0; j < fileassoc_nhooks; j++)
265		if (fileassoc_hooks[j].hook_cleanup_cb != NULL)
266			(fileassoc_hooks[j].hook_cleanup_cb)(tbl->tables[j],
267			    FILEASSOC_CLEANUP_TABLE);
268
269	/* Remove hash table and sysctl node */
270	hashdone(tbl->hash_tbl, M_TEMP);
271	LIST_REMOVE(tbl, hash_list);
272
273	return (0);
274}
275
276/*
277 * Run a callback for each hook entry in a table.
278 */
279int
280fileassoc_table_run(struct mount *mp, fileassoc_t id, fileassoc_cb_t cb)
281{
282	struct fileassoc_table *tbl;
283	struct fileassoc_hashhead *hh;
284	u_long i;
285
286	tbl = fileassoc_table_lookup(mp);
287	if (tbl == NULL)
288		return (EEXIST);
289
290	hh = tbl->hash_tbl;
291	for (i = 0; i < tbl->hash_size; i++) {
292		struct fileassoc_hash_entry *mhe;
293
294		LIST_FOREACH(mhe, &hh[i], entries) {
295			if (mhe->hooks[id] != NULL)
296				cb(mhe->hooks[id]);
297		}
298	}
299
300	return (0);
301}
302
303/*
304 * Clear a table for a given hook.
305 */
306int
307fileassoc_table_clear(struct mount *mp, fileassoc_t id)
308{
309	struct fileassoc_table *tbl;
310	struct fileassoc_hashhead *hh;
311	fileassoc_cleanup_cb_t cleanup_cb;
312	u_long i;
313
314	tbl = fileassoc_table_lookup(mp);
315	if (tbl == NULL)
316		return (EEXIST);
317
318	cleanup_cb = fileassoc_hooks[id].hook_cleanup_cb;
319
320	hh = tbl->hash_tbl;
321	for (i = 0; i < tbl->hash_size; i++) {
322		struct fileassoc_hash_entry *mhe;
323
324		LIST_FOREACH(mhe, &hh[i], entries) {
325			if ((mhe->hooks[id] != NULL) && cleanup_cb != NULL)
326				cleanup_cb(mhe->hooks[id],
327				    FILEASSOC_CLEANUP_FILE);
328
329			mhe->hooks[id] = NULL;
330		}
331	}
332
333	if ((tbl->tables[id] != NULL) && cleanup_cb != NULL)
334		cleanup_cb(tbl->tables[id], FILEASSOC_CLEANUP_TABLE);
335
336	tbl->tables[id] = NULL;
337
338	return (0);
339}
340
341/*
342 * Add hook-specific data on a fileassoc table.
343 */
344int
345fileassoc_tabledata_add(struct mount *mp, fileassoc_t id, void *data)
346{
347	struct fileassoc_table *tbl;
348
349	tbl = fileassoc_table_lookup(mp);
350	if (tbl == NULL)
351		return (EFAULT);
352
353	tbl->tables[id] = data;
354
355	return (0);
356}
357
358/*
359 * Clear hook-specific data on a fileassoc table.
360 */
361int
362fileassoc_tabledata_clear(struct mount *mp, fileassoc_t id)
363{
364	struct fileassoc_table *tbl;
365
366	tbl = fileassoc_table_lookup(mp);
367	if (tbl == NULL)
368		return (EFAULT);
369
370	tbl->tables[id] = NULL;
371
372	return (0);
373}
374
375/*
376 * Retrieve hook-specific data from a fileassoc table.
377 */
378void *
379fileassoc_tabledata_lookup(struct mount *mp, fileassoc_t id)
380{
381	struct fileassoc_table *tbl;
382
383	tbl = fileassoc_table_lookup(mp);
384	if (tbl == NULL)
385		return (NULL);
386
387	return (tbl->tables[id]);
388}
389
390/*
391 * Add a file entry to a table.
392 */
393static struct fileassoc_hash_entry *
394fileassoc_file_add(struct vnode *vp)
395{
396	struct fileassoc_table *tbl;
397	struct fileassoc_hashhead *vhh;
398	struct fileassoc_hash_entry *e;
399	struct vattr va;
400	size_t indx;
401	int error;
402
403	error = VOP_GETATTR(vp, &va, curlwp->l_cred, curlwp);
404	if (error)
405		return (NULL);
406
407	e = fileassoc_file_lookup(vp);
408	if (e != NULL)
409		return (e);
410
411	tbl = fileassoc_table_lookup(vp->v_mount);
412	if (tbl == NULL)
413		return (NULL);
414
415	/*
416	 * XXX: We should NOT rely on fileid here!
417	 */
418	indx = FILEASSOC_HASH(tbl, va.va_fileid);
419	vhh = &(tbl->hash_tbl[indx & ((tbl)->hash_mask)]);
420
421	e = malloc(sizeof(*e), M_TEMP, M_WAITOK | M_ZERO);
422	e->fileid = va.va_fileid;
423	LIST_INSERT_HEAD(vhh, e, entries);
424
425	return (e);
426}
427
428/*
429 * Delete a file entry from a table.
430 */
431int
432fileassoc_file_delete(struct vnode *vp)
433{
434	struct fileassoc_hash_entry *mhe;
435	int i;
436
437	mhe = fileassoc_file_lookup(vp);
438	if (mhe == NULL)
439		return (ENOENT);
440
441	LIST_REMOVE(mhe, entries);
442
443	for (i = 0; i < fileassoc_nhooks; i++)
444		if (fileassoc_hooks[i].hook_cleanup_cb != NULL)
445			(fileassoc_hooks[i].hook_cleanup_cb)(mhe->hooks[i],
446			    FILEASSOC_CLEANUP_FILE);
447
448	free(mhe, M_TEMP);
449
450	return (0);
451}
452
453/*
454 * Add a hook to a vnode.
455 */
456int
457fileassoc_add(struct vnode *vp, fileassoc_t id, void *data)
458{
459	struct fileassoc_hash_entry *e;
460
461	e = fileassoc_file_lookup(vp);
462	if (e == NULL) {
463		e = fileassoc_file_add(vp);
464		if (e == NULL)
465			return (ENOTDIR);
466	}
467
468	if (e->hooks[id] != NULL)
469		return (EEXIST);
470
471	e->hooks[id] = data;
472
473	return (0);
474}
475
476/*
477 * Clear a hook from a vnode.
478 */
479int
480fileassoc_clear(struct vnode *vp, fileassoc_t id)
481{
482	struct fileassoc_hash_entry *mhe;
483	fileassoc_cleanup_cb_t cleanup_cb;
484
485	mhe = fileassoc_file_lookup(vp);
486	if (mhe == NULL)
487		return (ENOENT);
488
489	cleanup_cb = fileassoc_hooks[id].hook_cleanup_cb;
490	if ((mhe->hooks[id] != NULL) && cleanup_cb != NULL)
491		cleanup_cb(mhe->hooks[id], FILEASSOC_CLEANUP_FILE);
492
493	mhe->hooks[id] = NULL;
494
495	return (0);
496}
497