[GitHub/mt8127/android_kernel_alcatel_ttab.git] / fs / posix_acl.c

/*
 * linux/fs/posix_acl.c
 *
 *  Copyright (C) 2002 by Andreas Gruenbacher <a.gruenbacher@computer.org>
 *
 *  Fixes from William Schumacher incorporated on 15 March 2001.
 *     (Reported by Charles Bertsch, <CBertsch@microtest.com>).
 */

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

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

#include <linux/errno.h>

EXPORT_SYMBOL(posix_acl_init);
EXPORT_SYMBOL(posix_acl_alloc);
EXPORT_SYMBOL(posix_acl_valid);
EXPORT_SYMBOL(posix_acl_equiv_mode);
EXPORT_SYMBOL(posix_acl_from_mode);

/*
 * Init a fresh posix_acl
 */
void
posix_acl_init(struct posix_acl *acl, int count)
{
	atomic_set(&acl->a_refcount, 1);
	acl->a_count = count;
}

/*
 * 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)
		posix_acl_init(acl, count);
	return acl;
}

/*
 * Clone an ACL.
 */
static 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;
	kuid_t prev_uid = INVALID_UID;
	kgid_t prev_gid = INVALID_GID;
	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) {
					state = ACL_USER;
					break;
				}
				return -EINVAL;

			case ACL_USER:
				if (state != ACL_USER)
					return -EINVAL;
				if (!uid_valid(pa->e_uid))
					return -EINVAL;
				if (uid_valid(prev_uid) &&
				    uid_lte(pa->e_uid, prev_uid))
					return -EINVAL;
				prev_uid = pa->e_uid;
				needs_mask = 1;
				break;

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

			case ACL_GROUP:
				if (state != ACL_GROUP)
					return -EINVAL;
				if (!gid_valid(pa->e_gid))
					return -EINVAL;
				if (gid_valid(prev_gid) &&
				    gid_lte(pa->e_gid, prev_gid))
					return -EINVAL;
				prev_gid = pa->e_gid;
				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, umode_t *mode_p)
{
	const struct posix_acl_entry *pa, *pe;
	umode_t mode = 0;
	int not_equiv = 0;

	/*
	 * A null ACL can always be presented as mode bits.
	 */
	if (!acl)
		return 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(umode_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_perm = (mode & S_IRWXU) >> 6;

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

	acl->a_entries[2].e_tag  = ACL_OTHER;
	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;

	want &= MAY_READ | MAY_WRITE | MAY_EXEC | MAY_NOT_BLOCK;

	FOREACH_ACL_ENTRY(pa, acl, pe) {
                switch(pa->e_tag) {
                        case ACL_USER_OBJ:
				/* (May have been checked already) */
				if (uid_eq(inode->i_uid, current_fsuid()))
                                        goto check_perm;
                                break;
                        case ACL_USER:
				if (uid_eq(pa->e_uid, 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_gid)) {
					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.
 */
static int posix_acl_create_masq(struct posix_acl *acl, umode_t *mode_p)
{
	struct posix_acl_entry *pa, *pe;
	struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL;
	umode_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;
}

/**
 * posix_acl_update_mode  -  update mode in set_acl
 *
 * Update the file mode when setting an ACL: compute the new file permission
 * bits based on the ACL.  In addition, if the ACL is equivalent to the new
 * file mode, set *acl to NULL to indicate that no ACL should be set.
 *
 * As with chmod, clear the setgit bit if the caller is not in the owning group
 * or capable of CAP_FSETID (see inode_change_ok).
 *
 * Called from set_acl inode operations.
 */
int posix_acl_update_mode(struct inode *inode, umode_t *mode_p,
			  struct posix_acl **acl)
{
	umode_t mode = inode->i_mode;
	int error;

	error = posix_acl_equiv_mode(*acl, &mode);
	if (error < 0)
		return error;
	if (error == 0)
		*acl = NULL;
	if (!in_group_p(inode->i_gid) &&
	    !capable_wrt_inode_uidgid(inode, CAP_FSETID))
		mode &= ~S_ISGID;
	*mode_p = mode;
	return 0;
}
EXPORT_SYMBOL(posix_acl_update_mode);

/*
 * Modify the ACL for the chmod syscall.
 */
static int posix_acl_chmod_masq(struct posix_acl *acl, umode_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;
}

int
posix_acl_create(struct posix_acl **acl, gfp_t gfp, umode_t *mode_p)
{
	struct posix_acl *clone = posix_acl_clone(*acl, gfp);
	int err = -ENOMEM;
	if (clone) {
		err = posix_acl_create_masq(clone, mode_p);
		if (err < 0) {
			posix_acl_release(clone);
			clone = NULL;
		}
	}
	posix_acl_release(*acl);
	*acl = clone;
	return err;
}
EXPORT_SYMBOL(posix_acl_create);

int
posix_acl_chmod(struct posix_acl **acl, gfp_t gfp, umode_t mode)
{
	struct posix_acl *clone = posix_acl_clone(*acl, gfp);
	int err = -ENOMEM;
	if (clone) {
		err = posix_acl_chmod_masq(clone, mode);
		if (err) {
			posix_acl_release(clone);
			clone = NULL;
		}
	}
	posix_acl_release(*acl);
	*acl = clone;
	return err;
}
EXPORT_SYMBOL(posix_acl_chmod);
Commit	Line	Data
1da177e4 LT	1	/*
	2	* linux/fs/posix_acl.c
	3	*
	4	* Copyright (C) 2002 by Andreas Gruenbacher <a.gruenbacher@computer.org>
	5	*
	6	* Fixes from William Schumacher incorporated on 15 March 2001.
	7	* (Reported by Charles Bertsch, <CBertsch@microtest.com>).
	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>
60063497	17	#include <linux/atomic.h>
1da177e4 LT	18	#include <linux/fs.h>
	19	#include <linux/sched.h>
	20	#include <linux/posix_acl.h>
630d9c47	21	#include <linux/export.h>
1da177e4 LT	22
	23	#include <linux/errno.h>
	24
f61f6da0	25	EXPORT_SYMBOL(posix_acl_init);
1da177e4	26	EXPORT_SYMBOL(posix_acl_alloc);
1da177e4 LT	27	EXPORT_SYMBOL(posix_acl_valid);
	28	EXPORT_SYMBOL(posix_acl_equiv_mode);
	29	EXPORT_SYMBOL(posix_acl_from_mode);
1da177e4	30
f61f6da0 CL	31	/*
	32	* Init a fresh posix_acl
	33	*/
	34	void
	35	posix_acl_init(struct posix_acl *acl, int count)
	36	{
	37	atomic_set(&acl->a_refcount, 1);
	38	acl->a_count = count;
	39	}
	40
1da177e4 LT	41	/*
	42	* Allocate a new ACL with the specified number of entries.
	43	*/
	44	struct posix_acl *
dd0fc66f	45	posix_acl_alloc(int count, gfp_t flags)
1da177e4 LT	46	{
	47	const size_t size = sizeof(struct posix_acl) +
	48	count * sizeof(struct posix_acl_entry);
	49	struct posix_acl *acl = kmalloc(size, flags);
f61f6da0 CL	50	if (acl)
f61f6da0 CL	51	posix_acl_init(acl, count);
1da177e4 LT	52	return acl;
	53	}
	54
	55	/*
	56	* Clone an ACL.
	57	*/
edde854e	58	static struct posix_acl *
dd0fc66f	59	posix_acl_clone(const struct posix_acl *acl, gfp_t flags)
1da177e4 LT	60	{
	61	struct posix_acl *clone = NULL;
	62
	63	if (acl) {
	64	int size = sizeof(struct posix_acl) + acl->a_count *
	65	sizeof(struct posix_acl_entry);
52978be6 AD	66	clone = kmemdup(acl, size, flags);
52978be6 AD	67	if (clone)
1da177e4	68	atomic_set(&clone->a_refcount, 1);
1da177e4 LT	69	}
	70	return clone;
	71	}
	72
	73	/*
	74	* Check if an acl is valid. Returns 0 if it is, or -E... otherwise.
	75	*/
	76	int
	77	posix_acl_valid(const struct posix_acl *acl)
	78	{
	79	const struct posix_acl_entry pa, pe;
	80	int state = ACL_USER_OBJ;
2f6f0654 EB	81	kuid_t prev_uid = INVALID_UID;
2f6f0654 EB	82	kgid_t prev_gid = INVALID_GID;
1da177e4 LT	83	int needs_mask = 0;
	84
	85	FOREACH_ACL_ENTRY(pa, acl, pe) {
	86	if (pa->e_perm & ~(ACL_READ\|ACL_WRITE\|ACL_EXECUTE))
	87	return -EINVAL;
	88	switch (pa->e_tag) {
	89	case ACL_USER_OBJ:
	90	if (state == ACL_USER_OBJ) {
1da177e4 LT	91	state = ACL_USER;
	92	break;
	93	}
	94	return -EINVAL;
	95
	96	case ACL_USER:
	97	if (state != ACL_USER)
	98	return -EINVAL;
2f6f0654	99	if (!uid_valid(pa->e_uid))
1da177e4	100	return -EINVAL;
2f6f0654 EB	101	if (uid_valid(prev_uid) &&
	102	uid_lte(pa->e_uid, prev_uid))
	103	return -EINVAL;
	104	prev_uid = pa->e_uid;
1da177e4 LT	105	needs_mask = 1;
	106	break;
	107
	108	case ACL_GROUP_OBJ:
	109	if (state == ACL_USER) {
1da177e4 LT	110	state = ACL_GROUP;
	111	break;
	112	}
	113	return -EINVAL;
	114
	115	case ACL_GROUP:
	116	if (state != ACL_GROUP)
	117	return -EINVAL;
2f6f0654 EB	118	if (!gid_valid(pa->e_gid))
	119	return -EINVAL;
	120	if (gid_valid(prev_gid) &&
	121	gid_lte(pa->e_gid, prev_gid))
1da177e4	122	return -EINVAL;
2f6f0654	123	prev_gid = pa->e_gid;
1da177e4 LT	124	needs_mask = 1;
	125	break;
	126
	127	case ACL_MASK:
	128	if (state != ACL_GROUP)
	129	return -EINVAL;
	130	state = ACL_OTHER;
	131	break;
	132
	133	case ACL_OTHER:
	134	if (state == ACL_OTHER \|\|
	135	(state == ACL_GROUP && !needs_mask)) {
	136	state = 0;
	137	break;
	138	}
	139	return -EINVAL;
	140
	141	default:
	142	return -EINVAL;
	143	}
	144	}
	145	if (state == 0)
	146	return 0;
	147	return -EINVAL;
	148	}
	149
	150	/*
	151	* Returns 0 if the acl can be exactly represented in the traditional
	152	* file mode permission bits, or else 1. Returns -E... on error.
	153	*/
	154	int
d6952123	155	posix_acl_equiv_mode(const struct posix_acl acl, umode_t mode_p)
1da177e4 LT	156	{
1da177e4 LT	157	const struct posix_acl_entry pa, pe;
d6952123	158	umode_t mode = 0;
1da177e4 LT	159	int not_equiv = 0;
1da177e4 LT	160
3d3da408 CH	161	/*
	162	* A null ACL can always be presented as mode bits.
	163	*/
	164	if (!acl)
	165	return 0;
	166
1da177e4 LT	167	FOREACH_ACL_ENTRY(pa, acl, pe) {
	168	switch (pa->e_tag) {
	169	case ACL_USER_OBJ:
	170	mode \|= (pa->e_perm & S_IRWXO) << 6;
	171	break;
	172	case ACL_GROUP_OBJ:
	173	mode \|= (pa->e_perm & S_IRWXO) << 3;
	174	break;
	175	case ACL_OTHER:
	176	mode \|= pa->e_perm & S_IRWXO;
	177	break;
	178	case ACL_MASK:
	179	mode = (mode & ~S_IRWXG) \|
	180	((pa->e_perm & S_IRWXO) << 3);
	181	not_equiv = 1;
	182	break;
	183	case ACL_USER:
	184	case ACL_GROUP:
	185	not_equiv = 1;
	186	break;
	187	default:
	188	return -EINVAL;
	189	}
	190	}
	191	if (mode_p)
	192	mode_p = (mode_p & ~S_IRWXUGO) \| mode;
	193	return not_equiv;
	194	}
	195
	196	/*
	197	* Create an ACL representing the file mode permission bits of an inode.
	198	*/
	199	struct posix_acl *
3a5fba19	200	posix_acl_from_mode(umode_t mode, gfp_t flags)
1da177e4 LT	201	{
	202	struct posix_acl *acl = posix_acl_alloc(3, flags);
	203	if (!acl)
	204	return ERR_PTR(-ENOMEM);
	205
	206	acl->a_entries[0].e_tag = ACL_USER_OBJ;
1da177e4 LT	207	acl->a_entries[0].e_perm = (mode & S_IRWXU) >> 6;
	208
	209	acl->a_entries[1].e_tag = ACL_GROUP_OBJ;
1da177e4 LT	210	acl->a_entries[1].e_perm = (mode & S_IRWXG) >> 3;
	211
	212	acl->a_entries[2].e_tag = ACL_OTHER;
1da177e4 LT	213	acl->a_entries[2].e_perm = (mode & S_IRWXO);
	214	return acl;
	215	}
	216
	217	/*
	218	* Return 0 if current is granted want access to the inode
	219	* by the acl. Returns -E... otherwise.
	220	*/
	221	int
	222	posix_acl_permission(struct inode inode, const struct posix_acl acl, int want)
	223	{
	224	const struct posix_acl_entry pa, pe, *mask_obj;
	225	int found = 0;
	226
d124b60a AG	227	want &= MAY_READ \| MAY_WRITE \| MAY_EXEC \| MAY_NOT_BLOCK;
d124b60a AG	228
1da177e4 LT	229	FOREACH_ACL_ENTRY(pa, acl, pe) {
	230	switch(pa->e_tag) {
	231	case ACL_USER_OBJ:
	232	/* (May have been checked already) */
2f6f0654	233	if (uid_eq(inode->i_uid, current_fsuid()))
1da177e4 LT	234	goto check_perm;
	235	break;
	236	case ACL_USER:
2f6f0654	237	if (uid_eq(pa->e_uid, current_fsuid()))
1da177e4 LT	238	goto mask;
	239	break;
	240	case ACL_GROUP_OBJ:
	241	if (in_group_p(inode->i_gid)) {
	242	found = 1;
	243	if ((pa->e_perm & want) == want)
	244	goto mask;
	245	}
	246	break;
	247	case ACL_GROUP:
2f6f0654	248	if (in_group_p(pa->e_gid)) {
1da177e4 LT	249	found = 1;
	250	if ((pa->e_perm & want) == want)
	251	goto mask;
	252	}
	253	break;
	254	case ACL_MASK:
	255	break;
	256	case ACL_OTHER:
	257	if (found)
	258	return -EACCES;
	259	else
	260	goto check_perm;
	261	default:
	262	return -EIO;
	263	}
	264	}
	265	return -EIO;
	266
	267	mask:
	268	for (mask_obj = pa+1; mask_obj != pe; mask_obj++) {
	269	if (mask_obj->e_tag == ACL_MASK) {
	270	if ((pa->e_perm & mask_obj->e_perm & want) == want)
	271	return 0;
	272	return -EACCES;
	273	}
	274	}
	275
	276	check_perm:
	277	if ((pa->e_perm & want) == want)
	278	return 0;
	279	return -EACCES;
	280	}
	281
	282	/*
	283	* Modify acl when creating a new inode. The caller must ensure the acl is
	284	* only referenced once.
	285	*
	286	* mode_p initially must contain the mode parameter to the open() / creat()
	287	* system calls. All permissions that are not granted by the acl are removed.
	288	* The permissions in the acl are changed to reflect the mode_p parameter.
	289	*/
d3fb6120	290	static int posix_acl_create_masq(struct posix_acl acl, umode_t mode_p)
1da177e4 LT	291	{
	292	struct posix_acl_entry pa, pe;
	293	struct posix_acl_entry group_obj = NULL, mask_obj = NULL;
d3fb6120	294	umode_t mode = *mode_p;
1da177e4 LT	295	int not_equiv = 0;
	296
	297	/* assert(atomic_read(acl->a_refcount) == 1); */
	298
	299	FOREACH_ACL_ENTRY(pa, acl, pe) {
	300	switch(pa->e_tag) {
	301	case ACL_USER_OBJ:
	302	pa->e_perm &= (mode >> 6) \| ~S_IRWXO;
	303	mode &= (pa->e_perm << 6) \| ~S_IRWXU;
	304	break;
	305
	306	case ACL_USER:
	307	case ACL_GROUP:
	308	not_equiv = 1;
	309	break;
	310
	311	case ACL_GROUP_OBJ:
	312	group_obj = pa;
	313	break;
	314
	315	case ACL_OTHER:
	316	pa->e_perm &= mode \| ~S_IRWXO;
	317	mode &= pa->e_perm \| ~S_IRWXO;
	318	break;
	319
	320	case ACL_MASK:
	321	mask_obj = pa;
	322	not_equiv = 1;
	323	break;
	324
	325	default:
	326	return -EIO;
	327	}
	328	}
	329
	330	if (mask_obj) {
	331	mask_obj->e_perm &= (mode >> 3) \| ~S_IRWXO;
	332	mode &= (mask_obj->e_perm << 3) \| ~S_IRWXG;
	333	} else {
	334	if (!group_obj)
	335	return -EIO;
	336	group_obj->e_perm &= (mode >> 3) \| ~S_IRWXO;
	337	mode &= (group_obj->e_perm << 3) \| ~S_IRWXG;
	338	}
	339
	340	mode_p = (mode_p & ~S_IRWXUGO) \| mode;
	341	return not_equiv;
	342	}
	343
4b9e9796 S	344	/**
	345	* posix_acl_update_mode - update mode in set_acl
	346	*
	347	* Update the file mode when setting an ACL: compute the new file permission
	348	* bits based on the ACL. In addition, if the ACL is equivalent to the new
	349	* file mode, set *acl to NULL to indicate that no ACL should be set.
	350	*
	351	* As with chmod, clear the setgit bit if the caller is not in the owning group
	352	* or capable of CAP_FSETID (see inode_change_ok).
	353	*
	354	* Called from set_acl inode operations.
	355	*/
	356	int posix_acl_update_mode(struct inode inode, umode_t mode_p,
	357	struct posix_acl **acl)
	358	{
	359	umode_t mode = inode->i_mode;
	360	int error;
	361
	362	error = posix_acl_equiv_mode(*acl, &mode);
	363	if (error < 0)
	364	return error;
	365	if (error == 0)
	366	*acl = NULL;
	367	if (!in_group_p(inode->i_gid) &&
	368	!capable_wrt_inode_uidgid(inode, CAP_FSETID))
	369	mode &= ~S_ISGID;
	370	*mode_p = mode;
	371	return 0;
	372	}
	373	EXPORT_SYMBOL(posix_acl_update_mode);
	374
1da177e4 LT	375	/*
	376	* Modify the ACL for the chmod syscall.
	377	*/
86bc704d	378	static int posix_acl_chmod_masq(struct posix_acl *acl, umode_t mode)
1da177e4 LT	379	{
	380	struct posix_acl_entry group_obj = NULL, mask_obj = NULL;
	381	struct posix_acl_entry pa, pe;
	382
	383	/* assert(atomic_read(acl->a_refcount) == 1); */
	384
	385	FOREACH_ACL_ENTRY(pa, acl, pe) {
	386	switch(pa->e_tag) {
	387	case ACL_USER_OBJ:
	388	pa->e_perm = (mode & S_IRWXU) >> 6;
	389	break;
	390
	391	case ACL_USER:
	392	case ACL_GROUP:
	393	break;
	394
	395	case ACL_GROUP_OBJ:
	396	group_obj = pa;
	397	break;
	398
	399	case ACL_MASK:
	400	mask_obj = pa;
	401	break;
	402
	403	case ACL_OTHER:
	404	pa->e_perm = (mode & S_IRWXO);
	405	break;
	406
	407	default:
	408	return -EIO;
	409	}
	410	}
	411
	412	if (mask_obj) {
	413	mask_obj->e_perm = (mode & S_IRWXG) >> 3;
	414	} else {
	415	if (!group_obj)
	416	return -EIO;
	417	group_obj->e_perm = (mode & S_IRWXG) >> 3;
	418	}
	419
	420	return 0;
	421	}
bc26ab5f	422
826cae2f	423	int
d3fb6120	424	posix_acl_create(struct posix_acl *acl, gfp_t gfp, umode_t mode_p)
826cae2f AV	425	{
	426	struct posix_acl clone = posix_acl_clone(acl, gfp);
	427	int err = -ENOMEM;
	428	if (clone) {
	429	err = posix_acl_create_masq(clone, mode_p);
	430	if (err < 0) {
	431	posix_acl_release(clone);
	432	clone = NULL;
	433	}
	434	}
	435	posix_acl_release(*acl);
	436	*acl = clone;
	437	return err;
	438	}
	439	EXPORT_SYMBOL(posix_acl_create);
	440
bc26ab5f	441	int
86bc704d	442	posix_acl_chmod(struct posix_acl **acl, gfp_t gfp, umode_t mode)
bc26ab5f AV	443	{
	444	struct posix_acl clone = posix_acl_clone(acl, gfp);
	445	int err = -ENOMEM;
	446	if (clone) {
	447	err = posix_acl_chmod_masq(clone, mode);
	448	if (err) {
	449	posix_acl_release(clone);
	450	clone = NULL;
	451	}
	452	}
	453	posix_acl_release(*acl);
	454	*acl = clone;
	455	return err;
	456	}
	457	EXPORT_SYMBOL(posix_acl_chmod);