[linux.git] / fs / posix_acl.c

/*
 * linux/fs/posix_acl.c
 *
 *  Copyright (C) 2002 by Andreas Gruenbacher <[email protected]>
 *
 *  Fixes from William Schumacher incorporated on 15 March 2001.
 *     (Reported by Charles Bertsch, <[email protected]>).
 */

/*
 *  This file contains generic functions for manipulating
 *  POSIX 1003.1e draft standard 17 ACLs.
 */

#include <linux/kernel.h>
#include <linux/slab.h>
#include <asm/atomic.h>
#include <linux/fs.h>
#include <linux/sched.h>
#include <linux/posix_acl.h>
#include <linux/module.h>

#include <linux/errno.h>

EXPORT_SYMBOL(posix_acl_alloc);
EXPORT_SYMBOL(posix_acl_clone);
EXPORT_SYMBOL(posix_acl_valid);
EXPORT_SYMBOL(posix_acl_equiv_mode);
EXPORT_SYMBOL(posix_acl_from_mode);
EXPORT_SYMBOL(posix_acl_create_masq);
EXPORT_SYMBOL(posix_acl_chmod_masq);
EXPORT_SYMBOL(posix_acl_permission);

/*
 * Allocate a new ACL with the specified number of entries.
 */
struct posix_acl *
posix_acl_alloc(int count, gfp_t flags)
{
	const size_t size = sizeof(struct posix_acl) +
	                    count * sizeof(struct posix_acl_entry);
	struct posix_acl *acl = kmalloc(size, flags);
	if (acl) {
		atomic_set(&acl->a_refcount, 1);
		acl->a_count = count;
	}
	return acl;
}

/*
 * Clone an ACL.
 */
struct posix_acl *
posix_acl_clone(const struct posix_acl *acl, gfp_t flags)
{
	struct posix_acl *clone = NULL;

	if (acl) {
		int size = sizeof(struct posix_acl) + acl->a_count *
		           sizeof(struct posix_acl_entry);
		clone = kmalloc(size, flags);
		if (clone) {
			memcpy(clone, acl, size);
			atomic_set(&clone->a_refcount, 1);
		}
	}
	return clone;
}

/*
 * Check if an acl is valid. Returns 0 if it is, or -E... otherwise.
 */
int
posix_acl_valid(const struct posix_acl *acl)
{
	const struct posix_acl_entry *pa, *pe;
	int state = ACL_USER_OBJ;
	unsigned int id = 0;  /* keep gcc happy */
	int needs_mask = 0;

	FOREACH_ACL_ENTRY(pa, acl, pe) {
		if (pa->e_perm & ~(ACL_READ|ACL_WRITE|ACL_EXECUTE))
			return -EINVAL;
		switch (pa->e_tag) {
			case ACL_USER_OBJ:
				if (state == ACL_USER_OBJ) {
					id = 0;
					state = ACL_USER;
					break;
				}
				return -EINVAL;

			case ACL_USER:
				if (state != ACL_USER)
					return -EINVAL;
				if (pa->e_id == ACL_UNDEFINED_ID ||
				    pa->e_id < id)
					return -EINVAL;
				id = pa->e_id + 1;
				needs_mask = 1;
				break;

			case ACL_GROUP_OBJ:
				if (state == ACL_USER) {
					id = 0;
					state = ACL_GROUP;
					break;
				}
				return -EINVAL;

			case ACL_GROUP:
				if (state != ACL_GROUP)
					return -EINVAL;
				if (pa->e_id == ACL_UNDEFINED_ID ||
				    pa->e_id < id)
					return -EINVAL;
				id = pa->e_id + 1;
				needs_mask = 1;
				break;

			case ACL_MASK:
				if (state != ACL_GROUP)
					return -EINVAL;
				state = ACL_OTHER;
				break;

			case ACL_OTHER:
				if (state == ACL_OTHER ||
				    (state == ACL_GROUP && !needs_mask)) {
					state = 0;
					break;
				}
				return -EINVAL;

			default:
				return -EINVAL;
		}
	}
	if (state == 0)
		return 0;
	return -EINVAL;
}

/*
 * Returns 0 if the acl can be exactly represented in the traditional
 * file mode permission bits, or else 1. Returns -E... on error.
 */
int
posix_acl_equiv_mode(const struct posix_acl *acl, mode_t *mode_p)
{
	const struct posix_acl_entry *pa, *pe;
	mode_t mode = 0;
	int not_equiv = 0;

	FOREACH_ACL_ENTRY(pa, acl, pe) {
		switch (pa->e_tag) {
			case ACL_USER_OBJ:
				mode |= (pa->e_perm & S_IRWXO) << 6;
				break;
			case ACL_GROUP_OBJ:
				mode |= (pa->e_perm & S_IRWXO) << 3;
				break;
			case ACL_OTHER:
				mode |= pa->e_perm & S_IRWXO;
				break;
			case ACL_MASK:
				mode = (mode & ~S_IRWXG) |
				       ((pa->e_perm & S_IRWXO) << 3);
				not_equiv = 1;
				break;
			case ACL_USER:
			case ACL_GROUP:
				not_equiv = 1;
				break;
			default:
				return -EINVAL;
		}
	}
        if (mode_p)
                *mode_p = (*mode_p & ~S_IRWXUGO) | mode;
        return not_equiv;
}

/*
 * Create an ACL representing the file mode permission bits of an inode.
 */
struct posix_acl *
posix_acl_from_mode(mode_t mode, gfp_t flags)
{
	struct posix_acl *acl = posix_acl_alloc(3, flags);
	if (!acl)
		return ERR_PTR(-ENOMEM);

	acl->a_entries[0].e_tag  = ACL_USER_OBJ;
	acl->a_entries[0].e_id   = ACL_UNDEFINED_ID;
	acl->a_entries[0].e_perm = (mode & S_IRWXU) >> 6;

	acl->a_entries[1].e_tag  = ACL_GROUP_OBJ;
	acl->a_entries[1].e_id   = ACL_UNDEFINED_ID;
	acl->a_entries[1].e_perm = (mode & S_IRWXG) >> 3;

	acl->a_entries[2].e_tag  = ACL_OTHER;
	acl->a_entries[2].e_id   = ACL_UNDEFINED_ID;
	acl->a_entries[2].e_perm = (mode & S_IRWXO);
	return acl;
}

/*
 * Return 0 if current is granted want access to the inode
 * by the acl. Returns -E... otherwise.
 */
int
posix_acl_permission(struct inode *inode, const struct posix_acl *acl, int want)
{
	const struct posix_acl_entry *pa, *pe, *mask_obj;
	int found = 0;

	FOREACH_ACL_ENTRY(pa, acl, pe) {
                switch(pa->e_tag) {
                        case ACL_USER_OBJ:
				/* (May have been checked already) */
                                if (inode->i_uid == current->fsuid)
                                        goto check_perm;
                                break;
                        case ACL_USER:
                                if (pa->e_id == current->fsuid)
                                        goto mask;
				break;
                        case ACL_GROUP_OBJ:
                                if (in_group_p(inode->i_gid)) {
					found = 1;
					if ((pa->e_perm & want) == want)
						goto mask;
                                }
				break;
                        case ACL_GROUP:
                                if (in_group_p(pa->e_id)) {
					found = 1;
					if ((pa->e_perm & want) == want)
						goto mask;
                                }
                                break;
                        case ACL_MASK:
                                break;
                        case ACL_OTHER:
				if (found)
					return -EACCES;
				else
					goto check_perm;
			default:
				return -EIO;
                }
        }
	return -EIO;

mask:
	for (mask_obj = pa+1; mask_obj != pe; mask_obj++) {
		if (mask_obj->e_tag == ACL_MASK) {
			if ((pa->e_perm & mask_obj->e_perm & want) == want)
				return 0;
			return -EACCES;
		}
	}

check_perm:
	if ((pa->e_perm & want) == want)
		return 0;
	return -EACCES;
}

/*
 * Modify acl when creating a new inode. The caller must ensure the acl is
 * only referenced once.
 *
 * mode_p initially must contain the mode parameter to the open() / creat()
 * system calls. All permissions that are not granted by the acl are removed.
 * The permissions in the acl are changed to reflect the mode_p parameter.
 */
int
posix_acl_create_masq(struct posix_acl *acl, mode_t *mode_p)
{
	struct posix_acl_entry *pa, *pe;
	struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL;
	mode_t mode = *mode_p;
	int not_equiv = 0;

	/* assert(atomic_read(acl->a_refcount) == 1); */

	FOREACH_ACL_ENTRY(pa, acl, pe) {
                switch(pa->e_tag) {
                        case ACL_USER_OBJ:
				pa->e_perm &= (mode >> 6) | ~S_IRWXO;
				mode &= (pa->e_perm << 6) | ~S_IRWXU;
				break;

			case ACL_USER:
			case ACL_GROUP:
				not_equiv = 1;
				break;

                        case ACL_GROUP_OBJ:
				group_obj = pa;
                                break;

                        case ACL_OTHER:
				pa->e_perm &= mode | ~S_IRWXO;
				mode &= pa->e_perm | ~S_IRWXO;
                                break;

                        case ACL_MASK:
				mask_obj = pa;
				not_equiv = 1;
                                break;

			default:
				return -EIO;
                }
        }

	if (mask_obj) {
		mask_obj->e_perm &= (mode >> 3) | ~S_IRWXO;
		mode &= (mask_obj->e_perm << 3) | ~S_IRWXG;
	} else {
		if (!group_obj)
			return -EIO;
		group_obj->e_perm &= (mode >> 3) | ~S_IRWXO;
		mode &= (group_obj->e_perm << 3) | ~S_IRWXG;
	}

	*mode_p = (*mode_p & ~S_IRWXUGO) | mode;
        return not_equiv;
}

/*
 * Modify the ACL for the chmod syscall.
 */
int
posix_acl_chmod_masq(struct posix_acl *acl, mode_t mode)
{
	struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL;
	struct posix_acl_entry *pa, *pe;

	/* assert(atomic_read(acl->a_refcount) == 1); */

	FOREACH_ACL_ENTRY(pa, acl, pe) {
		switch(pa->e_tag) {
			case ACL_USER_OBJ:
				pa->e_perm = (mode & S_IRWXU) >> 6;
				break;

			case ACL_USER:
			case ACL_GROUP:
				break;

			case ACL_GROUP_OBJ:
				group_obj = pa;
				break;

			case ACL_MASK:
				mask_obj = pa;
				break;

			case ACL_OTHER:
				pa->e_perm = (mode & S_IRWXO);
				break;

			default:
				return -EIO;
		}
	}

	if (mask_obj) {
		mask_obj->e_perm = (mode & S_IRWXG) >> 3;
	} else {
		if (!group_obj)
			return -EIO;
		group_obj->e_perm = (mode & S_IRWXG) >> 3;
	}

	return 0;
}
Commit	Line	Data
1da177e4 LT	1	/*
	2	* linux/fs/posix_acl.c
	3	*
	4	* Copyright (C) 2002 by Andreas Gruenbacher <[email protected]>
	5	*
	6	* Fixes from William Schumacher incorporated on 15 March 2001.
	7	* (Reported by Charles Bertsch, <[email protected]>).
	8	*/
	9
	10	/*
	11	* This file contains generic functions for manipulating
	12	* POSIX 1003.1e draft standard 17 ACLs.
	13	*/
	14
	15	#include <linux/kernel.h>
	16	#include <linux/slab.h>
	17	#include <asm/atomic.h>
	18	#include <linux/fs.h>
	19	#include <linux/sched.h>
	20	#include <linux/posix_acl.h>
	21	#include <linux/module.h>
	22
	23	#include <linux/errno.h>
	24
	25	EXPORT_SYMBOL(posix_acl_alloc);
	26	EXPORT_SYMBOL(posix_acl_clone);
	27	EXPORT_SYMBOL(posix_acl_valid);
	28	EXPORT_SYMBOL(posix_acl_equiv_mode);
	29	EXPORT_SYMBOL(posix_acl_from_mode);
	30	EXPORT_SYMBOL(posix_acl_create_masq);
	31	EXPORT_SYMBOL(posix_acl_chmod_masq);
	32	EXPORT_SYMBOL(posix_acl_permission);
	33
	34	/*
	35	* Allocate a new ACL with the specified number of entries.
	36	*/
	37	struct posix_acl *
dd0fc66f	38	posix_acl_alloc(int count, gfp_t flags)
1da177e4 LT	39	{
	40	const size_t size = sizeof(struct posix_acl) +
	41	count * sizeof(struct posix_acl_entry);
	42	struct posix_acl *acl = kmalloc(size, flags);
	43	if (acl) {
	44	atomic_set(&acl->a_refcount, 1);
	45	acl->a_count = count;
	46	}
	47	return acl;
	48	}
	49
	50	/*
	51	* Clone an ACL.
	52	*/
	53	struct posix_acl *
dd0fc66f	54	posix_acl_clone(const struct posix_acl *acl, gfp_t flags)
1da177e4 LT	55	{
	56	struct posix_acl *clone = NULL;
	57
	58	if (acl) {
	59	int size = sizeof(struct posix_acl) + acl->a_count *
	60	sizeof(struct posix_acl_entry);
	61	clone = kmalloc(size, flags);
	62	if (clone) {
	63	memcpy(clone, acl, size);
	64	atomic_set(&clone->a_refcount, 1);
	65	}
	66	}
	67	return clone;
	68	}
	69
	70	/*
	71	* Check if an acl is valid. Returns 0 if it is, or -E... otherwise.
	72	*/
	73	int
	74	posix_acl_valid(const struct posix_acl *acl)
	75	{
	76	const struct posix_acl_entry pa, pe;
	77	int state = ACL_USER_OBJ;
	78	unsigned int id = 0; /* keep gcc happy */
	79	int needs_mask = 0;
	80
	81	FOREACH_ACL_ENTRY(pa, acl, pe) {
	82	if (pa->e_perm & ~(ACL_READ\|ACL_WRITE\|ACL_EXECUTE))
	83	return -EINVAL;
	84	switch (pa->e_tag) {
	85	case ACL_USER_OBJ:
	86	if (state == ACL_USER_OBJ) {
	87	id = 0;
	88	state = ACL_USER;
	89	break;
	90	}
	91	return -EINVAL;
	92
	93	case ACL_USER:
	94	if (state != ACL_USER)
	95	return -EINVAL;
	96	if (pa->e_id == ACL_UNDEFINED_ID \|\|
	97	pa->e_id < id)
	98	return -EINVAL;
	99	id = pa->e_id + 1;
	100	needs_mask = 1;
	101	break;
	102
	103	case ACL_GROUP_OBJ:
	104	if (state == ACL_USER) {
	105	id = 0;
	106	state = ACL_GROUP;
	107	break;
	108	}
	109	return -EINVAL;
	110
	111	case ACL_GROUP:
	112	if (state != ACL_GROUP)
	113	return -EINVAL;
	114	if (pa->e_id == ACL_UNDEFINED_ID \|\|
	115	pa->e_id < id)
	116	return -EINVAL;
	117	id = pa->e_id + 1;
	118	needs_mask = 1;
119	break;
120
121	case ACL_MASK:
122	if (state != ACL_GROUP)
123	return -EINVAL;
124	state = ACL_OTHER;
125	break;
126
127	case ACL_OTHER:
128	if (state == ACL_OTHER \|\|
129	(state == ACL_GROUP && !needs_mask)) {
130	state = 0;
131	break;
132	}
133	return -EINVAL;
134
135	default:
136	return -EINVAL;
137	}
138	}
139	if (state == 0)
140	return 0;
141	return -EINVAL;
142	}
143
144	/*
145	* Returns 0 if the acl can be exactly represented in the traditional
146	* file mode permission bits, or else 1. Returns -E... on error.
147	*/
148	int
149	posix_acl_equiv_mode(const struct posix_acl acl, mode_t mode_p)
150	{
151	const struct posix_acl_entry pa, pe;
152	mode_t mode = 0;
153	int not_equiv = 0;
154
155	FOREACH_ACL_ENTRY(pa, acl, pe) {
156	switch (pa->e_tag) {
157	case ACL_USER_OBJ:
158	mode \|= (pa->e_perm & S_IRWXO) << 6;
159	break;
160	case ACL_GROUP_OBJ:
161	mode \|= (pa->e_perm & S_IRWXO) << 3;
162	break;
163	case ACL_OTHER:
164	mode \|= pa->e_perm & S_IRWXO;
165	break;
166	case ACL_MASK:
167	mode = (mode & ~S_IRWXG) \|
168	((pa->e_perm & S_IRWXO) << 3);
169	not_equiv = 1;
170	break;
171	case ACL_USER:
172	case ACL_GROUP:
173	not_equiv = 1;
174	break;
175	default:
176	return -EINVAL;
177	}
178	}
179	if (mode_p)
180	mode_p = (mode_p & ~S_IRWXUGO) \| mode;
181	return not_equiv;
182	}
183
184	/*
185	* Create an ACL representing the file mode permission bits of an inode.
186	*/
187	struct posix_acl *
dd0fc66f	188	posix_acl_from_mode(mode_t mode, gfp_t flags)
1da177e4 LT	189	{
	190	struct posix_acl *acl = posix_acl_alloc(3, flags);
	191	if (!acl)
	192	return ERR_PTR(-ENOMEM);
	193
	194	acl->a_entries[0].e_tag = ACL_USER_OBJ;
	195	acl->a_entries[0].e_id = ACL_UNDEFINED_ID;
	196	acl->a_entries[0].e_perm = (mode & S_IRWXU) >> 6;
	197
	198	acl->a_entries[1].e_tag = ACL_GROUP_OBJ;
	199	acl->a_entries[1].e_id = ACL_UNDEFINED_ID;
	200	acl->a_entries[1].e_perm = (mode & S_IRWXG) >> 3;
	201
	202	acl->a_entries[2].e_tag = ACL_OTHER;
	203	acl->a_entries[2].e_id = ACL_UNDEFINED_ID;
	204	acl->a_entries[2].e_perm = (mode & S_IRWXO);
	205	return acl;
	206	}
	207
	208	/*
	209	* Return 0 if current is granted want access to the inode
	210	* by the acl. Returns -E... otherwise.
	211	*/
	212	int
	213	posix_acl_permission(struct inode inode, const struct posix_acl acl, int want)
	214	{
	215	const struct posix_acl_entry pa, pe, *mask_obj;
	216	int found = 0;
	217
	218	FOREACH_ACL_ENTRY(pa, acl, pe) {
	219	switch(pa->e_tag) {
	220	case ACL_USER_OBJ:
	221	/* (May have been checked already) */
	222	if (inode->i_uid == current->fsuid)
	223	goto check_perm;
	224	break;
	225	case ACL_USER:
	226	if (pa->e_id == current->fsuid)
	227	goto mask;
	228	break;
	229	case ACL_GROUP_OBJ:
	230	if (in_group_p(inode->i_gid)) {
	231	found = 1;
	232	if ((pa->e_perm & want) == want)
	233	goto mask;
	234	}
	235	break;
	236	case ACL_GROUP:
	237	if (in_group_p(pa->e_id)) {
	238	found = 1;
	239	if ((pa->e_perm & want) == want)
	240	goto mask;
	241	}
	242	break;
	243	case ACL_MASK:
	244	break;
	245	case ACL_OTHER:
	246	if (found)
	247	return -EACCES;
	248	else
	249	goto check_perm;
	250	default:
	251	return -EIO;
	252	}
253	}
254	return -EIO;
255
256	mask:
257	for (mask_obj = pa+1; mask_obj != pe; mask_obj++) {
258	if (mask_obj->e_tag == ACL_MASK) {
259	if ((pa->e_perm & mask_obj->e_perm & want) == want)
260	return 0;
261	return -EACCES;
262	}
263	}
264
265	check_perm:
266	if ((pa->e_perm & want) == want)
267	return 0;
268	return -EACCES;
269	}
270
271	/*
272	* Modify acl when creating a new inode. The caller must ensure the acl is
273	* only referenced once.
274	*
275	* mode_p initially must contain the mode parameter to the open() / creat()
276	* system calls. All permissions that are not granted by the acl are removed.
277	* The permissions in the acl are changed to reflect the mode_p parameter.
278	*/
279	int
280	posix_acl_create_masq(struct posix_acl acl, mode_t mode_p)
281	{
282	struct posix_acl_entry pa, pe;
283	struct posix_acl_entry group_obj = NULL, mask_obj = NULL;
284	mode_t mode = *mode_p;
285	int not_equiv = 0;
286
287	/* assert(atomic_read(acl->a_refcount) == 1); */
288
289	FOREACH_ACL_ENTRY(pa, acl, pe) {
290	switch(pa->e_tag) {
291	case ACL_USER_OBJ:
292	pa->e_perm &= (mode >> 6) \| ~S_IRWXO;
293	mode &= (pa->e_perm << 6) \| ~S_IRWXU;
294	break;
295
296	case ACL_USER:
297	case ACL_GROUP:
298	not_equiv = 1;
299	break;
300
301	case ACL_GROUP_OBJ:
302	group_obj = pa;
303	break;
304
305	case ACL_OTHER:
306	pa->e_perm &= mode \| ~S_IRWXO;
307	mode &= pa->e_perm \| ~S_IRWXO;
308	break;
309
310	case ACL_MASK:
311	mask_obj = pa;
312	not_equiv = 1;
313	break;
314
315	default:
316	return -EIO;
317	}
318	}
319
320	if (mask_obj) {
321	mask_obj->e_perm &= (mode >> 3) \| ~S_IRWXO;
322	mode &= (mask_obj->e_perm << 3) \| ~S_IRWXG;
323	} else {
324	if (!group_obj)
325	return -EIO;
326	group_obj->e_perm &= (mode >> 3) \| ~S_IRWXO;
327	mode &= (group_obj->e_perm << 3) \| ~S_IRWXG;
328	}
329
330	mode_p = (mode_p & ~S_IRWXUGO) \| mode;
331	return not_equiv;
332	}
333
334	/*
335	* Modify the ACL for the chmod syscall.
336	*/
337	int
338	posix_acl_chmod_masq(struct posix_acl *acl, mode_t mode)
339	{
340	struct posix_acl_entry group_obj = NULL, mask_obj = NULL;
341	struct posix_acl_entry pa, pe;
342
343	/* assert(atomic_read(acl->a_refcount) == 1); */
344
345	FOREACH_ACL_ENTRY(pa, acl, pe) {
346	switch(pa->e_tag) {
347	case ACL_USER_OBJ:
348	pa->e_perm = (mode & S_IRWXU) >> 6;
349	break;
350
351	case ACL_USER:
352	case ACL_GROUP:
353	break;
354
355	case ACL_GROUP_OBJ:
356	group_obj = pa;
357	break;
358
359	case ACL_MASK:
360	mask_obj = pa;
361	break;
362
363	case ACL_OTHER:
364	pa->e_perm = (mode & S_IRWXO);
365	break;
366
367	default:
368	return -EIO;
369	}
370	}
371
372	if (mask_obj) {
373	mask_obj->e_perm = (mode & S_IRWXG) >> 3;
374	} else {
375	if (!group_obj)
376	return -EIO;
377	group_obj->e_perm = (mode & S_IRWXG) >> 3;
378	}
379
380	return 0;
381	}