4 * Copyright (C) 2002 by Andreas Gruenbacher <a.gruenbacher@computer.org>
6 * Fixes from William Schumacher incorporated on 15 March 2001.
7 * (Reported by Charles Bertsch, <CBertsch@microtest.com>).
11 * This file contains generic functions for manipulating
12 * POSIX 1003.1e draft standard 17 ACLs.
15 #include <linux/kernel.h>
16 #include <linux/slab.h>
17 #include <asm/atomic.h>
19 #include <linux/sched.h>
20 #include <linux/posix_acl.h>
21 #include <linux/module.h>
23 #include <linux/errno.h>
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
);
35 * Allocate a new ACL with the specified number of entries.
38 posix_acl_alloc(int count
, gfp_t flags
)
40 const size_t size
= sizeof(struct posix_acl
) +
41 count
* sizeof(struct posix_acl_entry
);
42 struct posix_acl
*acl
= kmalloc(size
, flags
);
44 atomic_set(&acl
->a_refcount
, 1);
54 posix_acl_clone(const struct posix_acl
*acl
, gfp_t flags
)
56 struct posix_acl
*clone
= NULL
;
59 int size
= sizeof(struct posix_acl
) + acl
->a_count
*
60 sizeof(struct posix_acl_entry
);
61 clone
= kmemdup(acl
, size
, flags
);
63 atomic_set(&clone
->a_refcount
, 1);
69 * Check if an acl is valid. Returns 0 if it is, or -E... otherwise.
72 posix_acl_valid(const struct posix_acl
*acl
)
74 const struct posix_acl_entry
*pa
, *pe
;
75 int state
= ACL_USER_OBJ
;
76 unsigned int id
= 0; /* keep gcc happy */
79 FOREACH_ACL_ENTRY(pa
, acl
, pe
) {
80 if (pa
->e_perm
& ~(ACL_READ
|ACL_WRITE
|ACL_EXECUTE
))
84 if (state
== ACL_USER_OBJ
) {
92 if (state
!= ACL_USER
)
94 if (pa
->e_id
== ACL_UNDEFINED_ID
||
102 if (state
== ACL_USER
) {
110 if (state
!= ACL_GROUP
)
112 if (pa
->e_id
== ACL_UNDEFINED_ID
||
120 if (state
!= ACL_GROUP
)
126 if (state
== ACL_OTHER
||
127 (state
== ACL_GROUP
&& !needs_mask
)) {
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.
147 posix_acl_equiv_mode(const struct posix_acl
*acl
, mode_t
*mode_p
)
149 const struct posix_acl_entry
*pa
, *pe
;
153 FOREACH_ACL_ENTRY(pa
, acl
, pe
) {
156 mode
|= (pa
->e_perm
& S_IRWXO
) << 6;
159 mode
|= (pa
->e_perm
& S_IRWXO
) << 3;
162 mode
|= pa
->e_perm
& S_IRWXO
;
165 mode
= (mode
& ~S_IRWXG
) |
166 ((pa
->e_perm
& S_IRWXO
) << 3);
178 *mode_p
= (*mode_p
& ~S_IRWXUGO
) | mode
;
183 * Create an ACL representing the file mode permission bits of an inode.
186 posix_acl_from_mode(mode_t mode
, gfp_t flags
)
188 struct posix_acl
*acl
= posix_acl_alloc(3, flags
);
190 return ERR_PTR(-ENOMEM
);
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;
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;
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
);
207 * Return 0 if current is granted want access to the inode
208 * by the acl. Returns -E... otherwise.
211 posix_acl_permission(struct inode
*inode
, const struct posix_acl
*acl
, int want
)
213 const struct posix_acl_entry
*pa
, *pe
, *mask_obj
;
216 FOREACH_ACL_ENTRY(pa
, acl
, pe
) {
219 /* (May have been checked already) */
220 if (inode
->i_uid
== current_fsuid())
224 if (pa
->e_id
== current_fsuid())
228 if (in_group_p(inode
->i_gid
)) {
230 if ((pa
->e_perm
& want
) == want
)
235 if (in_group_p(pa
->e_id
)) {
237 if ((pa
->e_perm
& want
) == want
)
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
)
264 if ((pa
->e_perm
& want
) == want
)
270 * Modify acl when creating a new inode. The caller must ensure the acl is
271 * only referenced once.
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.
278 posix_acl_create_masq(struct posix_acl
*acl
, mode_t
*mode_p
)
280 struct posix_acl_entry
*pa
, *pe
;
281 struct posix_acl_entry
*group_obj
= NULL
, *mask_obj
= NULL
;
282 mode_t mode
= *mode_p
;
285 /* assert(atomic_read(acl->a_refcount) == 1); */
287 FOREACH_ACL_ENTRY(pa
, acl
, pe
) {
290 pa
->e_perm
&= (mode
>> 6) | ~S_IRWXO
;
291 mode
&= (pa
->e_perm
<< 6) | ~S_IRWXU
;
304 pa
->e_perm
&= mode
| ~S_IRWXO
;
305 mode
&= pa
->e_perm
| ~S_IRWXO
;
319 mask_obj
->e_perm
&= (mode
>> 3) | ~S_IRWXO
;
320 mode
&= (mask_obj
->e_perm
<< 3) | ~S_IRWXG
;
324 group_obj
->e_perm
&= (mode
>> 3) | ~S_IRWXO
;
325 mode
&= (group_obj
->e_perm
<< 3) | ~S_IRWXG
;
328 *mode_p
= (*mode_p
& ~S_IRWXUGO
) | mode
;
333 * Modify the ACL for the chmod syscall.
336 posix_acl_chmod_masq(struct posix_acl
*acl
, mode_t mode
)
338 struct posix_acl_entry
*group_obj
= NULL
, *mask_obj
= NULL
;
339 struct posix_acl_entry
*pa
, *pe
;
341 /* assert(atomic_read(acl->a_refcount) == 1); */
343 FOREACH_ACL_ENTRY(pa
, acl
, pe
) {
346 pa
->e_perm
= (mode
& S_IRWXU
) >> 6;
362 pa
->e_perm
= (mode
& S_IRWXO
);
371 mask_obj
->e_perm
= (mode
& S_IRWXG
) >> 3;
375 group_obj
->e_perm
= (mode
& S_IRWXG
) >> 3;
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