[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 = kmemdup(acl, size, flags);
		if (clone)
			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);
52978be6 AD	61	clone = kmemdup(acl, size, flags);
52978be6 AD	62	if (clone)
1da177e4	63	atomic_set(&clone->a_refcount, 1);
1da177e4 LT	64	}
	65	return clone;
	66	}
	67
	68	/*
	69	* Check if an acl is valid. Returns 0 if it is, or -E... otherwise.
	70	*/
	71	int
	72	posix_acl_valid(const struct posix_acl *acl)
	73	{
	74	const struct posix_acl_entry pa, pe;
	75	int state = ACL_USER_OBJ;
	76	unsigned int id = 0; /* keep gcc happy */
	77	int needs_mask = 0;
	78
	79	FOREACH_ACL_ENTRY(pa, acl, pe) {
	80	if (pa->e_perm & ~(ACL_READ\|ACL_WRITE\|ACL_EXECUTE))
	81	return -EINVAL;
	82	switch (pa->e_tag) {
	83	case ACL_USER_OBJ:
	84	if (state == ACL_USER_OBJ) {
	85	id = 0;
	86	state = ACL_USER;
	87	break;
	88	}
	89	return -EINVAL;
	90
	91	case ACL_USER:
	92	if (state != ACL_USER)
	93	return -EINVAL;
	94	if (pa->e_id == ACL_UNDEFINED_ID \|\|
	95	pa->e_id < id)
	96	return -EINVAL;
	97	id = pa->e_id + 1;
	98	needs_mask = 1;
	99	break;
	100
	101	case ACL_GROUP_OBJ:
	102	if (state == ACL_USER) {
	103	id = 0;
	104	state = ACL_GROUP;
	105	break;
	106	}
	107	return -EINVAL;
	108
	109	case ACL_GROUP:
	110	if (state != ACL_GROUP)
	111	return -EINVAL;
	112	if (pa->e_id == ACL_UNDEFINED_ID \|\|
	113	pa->e_id < id)
	114	return -EINVAL;
	115	id = pa->e_id + 1;
	116	needs_mask = 1;
	117	break;
	118
	119	case ACL_MASK:
	120	if (state != ACL_GROUP)
	121	return -EINVAL;
	122	state = ACL_OTHER;
	123	break;
	124
	125	case ACL_OTHER:
	126	if (state == ACL_OTHER \|\|
	127	(state == ACL_GROUP && !needs_mask)) {
128	state = 0;
129	break;
130	}
131	return -EINVAL;
132
133	default:
134	return -EINVAL;
135	}
136	}
137	if (state == 0)
138	return 0;
139	return -EINVAL;
140	}
141
142	/*
143	* Returns 0 if the acl can be exactly represented in the traditional
144	* file mode permission bits, or else 1. Returns -E... on error.
145	*/
146	int
147	posix_acl_equiv_mode(const struct posix_acl acl, mode_t mode_p)
148	{
149	const struct posix_acl_entry pa, pe;
150	mode_t mode = 0;
151	int not_equiv = 0;
152
153	FOREACH_ACL_ENTRY(pa, acl, pe) {
154	switch (pa->e_tag) {
155	case ACL_USER_OBJ:
156	mode \|= (pa->e_perm & S_IRWXO) << 6;
157	break;
158	case ACL_GROUP_OBJ:
159	mode \|= (pa->e_perm & S_IRWXO) << 3;
160	break;
161	case ACL_OTHER:
162	mode \|= pa->e_perm & S_IRWXO;
163	break;
164	case ACL_MASK:
165	mode = (mode & ~S_IRWXG) \|
166	((pa->e_perm & S_IRWXO) << 3);
167	not_equiv = 1;
168	break;
169	case ACL_USER:
170	case ACL_GROUP:
171	not_equiv = 1;
172	break;
173	default:
174	return -EINVAL;
175	}
176	}
177	if (mode_p)
178	mode_p = (mode_p & ~S_IRWXUGO) \| mode;
179	return not_equiv;
180	}
181
182	/*
183	* Create an ACL representing the file mode permission bits of an inode.
184	*/
185	struct posix_acl *
dd0fc66f	186	posix_acl_from_mode(mode_t mode, gfp_t flags)
1da177e4 LT	187	{
	188	struct posix_acl *acl = posix_acl_alloc(3, flags);
	189	if (!acl)
	190	return ERR_PTR(-ENOMEM);
	191
	192	acl->a_entries[0].e_tag = ACL_USER_OBJ;
	193	acl->a_entries[0].e_id = ACL_UNDEFINED_ID;
	194	acl->a_entries[0].e_perm = (mode & S_IRWXU) >> 6;
	195
	196	acl->a_entries[1].e_tag = ACL_GROUP_OBJ;
	197	acl->a_entries[1].e_id = ACL_UNDEFINED_ID;
	198	acl->a_entries[1].e_perm = (mode & S_IRWXG) >> 3;
	199
	200	acl->a_entries[2].e_tag = ACL_OTHER;
	201	acl->a_entries[2].e_id = ACL_UNDEFINED_ID;
	202	acl->a_entries[2].e_perm = (mode & S_IRWXO);
	203	return acl;
	204	}
	205
	206	/*
	207	* Return 0 if current is granted want access to the inode
	208	* by the acl. Returns -E... otherwise.
	209	*/
	210	int
	211	posix_acl_permission(struct inode inode, const struct posix_acl acl, int want)
	212	{
	213	const struct posix_acl_entry pa, pe, *mask_obj;
	214	int found = 0;
	215
	216	FOREACH_ACL_ENTRY(pa, acl, pe) {
	217	switch(pa->e_tag) {
	218	case ACL_USER_OBJ:
	219	/* (May have been checked already) */
da9592ed	220	if (inode->i_uid == current_fsuid())
1da177e4 LT	221	goto check_perm;
	222	break;
	223	case ACL_USER:
da9592ed	224	if (pa->e_id == current_fsuid())
1da177e4 LT	225	goto mask;
	226	break;
	227	case ACL_GROUP_OBJ:
	228	if (in_group_p(inode->i_gid)) {
	229	found = 1;
	230	if ((pa->e_perm & want) == want)
	231	goto mask;
	232	}
	233	break;
	234	case ACL_GROUP:
	235	if (in_group_p(pa->e_id)) {
	236	found = 1;
	237	if ((pa->e_perm & want) == want)
	238	goto mask;
	239	}
	240	break;
	241	case ACL_MASK:
	242	break;
	243	case ACL_OTHER:
	244	if (found)
	245	return -EACCES;
	246	else
	247	goto check_perm;
	248	default:
	249	return -EIO;
	250	}
	251	}
	252	return -EIO;
	253
	254	mask:
	255	for (mask_obj = pa+1; mask_obj != pe; mask_obj++) {
	256	if (mask_obj->e_tag == ACL_MASK) {
	257	if ((pa->e_perm & mask_obj->e_perm & want) == want)
	258	return 0;
	259	return -EACCES;
	260	}
	261	}
	262
	263	check_perm:
	264	if ((pa->e_perm & want) == want)
	265	return 0;
	266	return -EACCES;
	267	}
	268
	269	/*
	270	* Modify acl when creating a new inode. The caller must ensure the acl is
	271	* only referenced once.
	272	*
	273	* mode_p initially must contain the mode parameter to the open() / creat()
	274	* system calls. All permissions that are not granted by the acl are removed.
	275	* The permissions in the acl are changed to reflect the mode_p parameter.
	276	*/
	277	int
	278	posix_acl_create_masq(struct posix_acl acl, mode_t mode_p)
	279	{
	280	struct posix_acl_entry pa, pe;
	281	struct posix_acl_entry group_obj = NULL, mask_obj = NULL;
	282	mode_t mode = *mode_p;
	283	int not_equiv = 0;
	284
	285	/* assert(atomic_read(acl->a_refcount) == 1); */
	286
	287	FOREACH_ACL_ENTRY(pa, acl, pe) {
	288	switch(pa->e_tag) {
289	case ACL_USER_OBJ:
290	pa->e_perm &= (mode >> 6) \| ~S_IRWXO;
291	mode &= (pa->e_perm << 6) \| ~S_IRWXU;
292	break;
293
294	case ACL_USER:
295	case ACL_GROUP:
296	not_equiv = 1;
297	break;
298
299	case ACL_GROUP_OBJ:
300	group_obj = pa;
301	break;
302
303	case ACL_OTHER:
304	pa->e_perm &= mode \| ~S_IRWXO;
305	mode &= pa->e_perm \| ~S_IRWXO;
306	break;
307
308	case ACL_MASK:
309	mask_obj = pa;
310	not_equiv = 1;
311	break;
312
313	default:
314	return -EIO;
315	}
316	}
317
318	if (mask_obj) {
319	mask_obj->e_perm &= (mode >> 3) \| ~S_IRWXO;
320	mode &= (mask_obj->e_perm << 3) \| ~S_IRWXG;
321	} else {
322	if (!group_obj)
323	return -EIO;
324	group_obj->e_perm &= (mode >> 3) \| ~S_IRWXO;
325	mode &= (group_obj->e_perm << 3) \| ~S_IRWXG;
326	}
327
328	mode_p = (mode_p & ~S_IRWXUGO) \| mode;
329	return not_equiv;
330	}
331
332	/*
333	* Modify the ACL for the chmod syscall.
334	*/
335	int
336	posix_acl_chmod_masq(struct posix_acl *acl, mode_t mode)
337	{
338	struct posix_acl_entry group_obj = NULL, mask_obj = NULL;
339	struct posix_acl_entry pa, pe;
340
341	/* assert(atomic_read(acl->a_refcount) == 1); */
342
343	FOREACH_ACL_ENTRY(pa, acl, pe) {
344	switch(pa->e_tag) {
345	case ACL_USER_OBJ:
346	pa->e_perm = (mode & S_IRWXU) >> 6;
347	break;
348
349	case ACL_USER:
350	case ACL_GROUP:
351	break;
352
353	case ACL_GROUP_OBJ:
354	group_obj = pa;
355	break;
356
357	case ACL_MASK:
358	mask_obj = pa;
359	break;
360
361	case ACL_OTHER:
362	pa->e_perm = (mode & S_IRWXO);
363	break;
364
365	default:
366	return -EIO;
367	}
368	}
369
370	if (mask_obj) {
371	mask_obj->e_perm = (mode & S_IRWXG) >> 3;
372	} else {
373	if (!group_obj)
374	return -EIO;
375	group_obj->e_perm = (mode & S_IRWXG) >> 3;
376	}
377
378	return 0;
379	}