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git.proxmox.com Git - mirror_ubuntu-eoan-kernel.git/blob - fs/posix_acl.c
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
= kmalloc(size
, flags
);
63 memcpy(clone
, acl
, size
);
64 atomic_set(&clone
->a_refcount
, 1);
71 * Check if an acl is valid. Returns 0 if it is, or -E... otherwise.
74 posix_acl_valid(const struct posix_acl
*acl
)
76 const struct posix_acl_entry
*pa
, *pe
;
77 int state
= ACL_USER_OBJ
;
78 unsigned int id
= 0; /* keep gcc happy */
81 FOREACH_ACL_ENTRY(pa
, acl
, pe
) {
82 if (pa
->e_perm
& ~(ACL_READ
|ACL_WRITE
|ACL_EXECUTE
))
86 if (state
== ACL_USER_OBJ
) {
94 if (state
!= ACL_USER
)
96 if (pa
->e_id
== ACL_UNDEFINED_ID
||
104 if (state
== ACL_USER
) {
112 if (state
!= ACL_GROUP
)
114 if (pa
->e_id
== ACL_UNDEFINED_ID
||
122 if (state
!= ACL_GROUP
)
128 if (state
== ACL_OTHER
||
129 (state
== ACL_GROUP
&& !needs_mask
)) {
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.
149 posix_acl_equiv_mode(const struct posix_acl
*acl
, mode_t
*mode_p
)
151 const struct posix_acl_entry
*pa
, *pe
;
155 FOREACH_ACL_ENTRY(pa
, acl
, pe
) {
158 mode
|= (pa
->e_perm
& S_IRWXO
) << 6;
161 mode
|= (pa
->e_perm
& S_IRWXO
) << 3;
164 mode
|= pa
->e_perm
& S_IRWXO
;
167 mode
= (mode
& ~S_IRWXG
) |
168 ((pa
->e_perm
& S_IRWXO
) << 3);
180 *mode_p
= (*mode_p
& ~S_IRWXUGO
) | mode
;
185 * Create an ACL representing the file mode permission bits of an inode.
188 posix_acl_from_mode(mode_t mode
, gfp_t flags
)
190 struct posix_acl
*acl
= posix_acl_alloc(3, flags
);
192 return ERR_PTR(-ENOMEM
);
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;
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;
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
);
209 * Return 0 if current is granted want access to the inode
210 * by the acl. Returns -E... otherwise.
213 posix_acl_permission(struct inode
*inode
, const struct posix_acl
*acl
, int want
)
215 const struct posix_acl_entry
*pa
, *pe
, *mask_obj
;
218 FOREACH_ACL_ENTRY(pa
, acl
, pe
) {
221 /* (May have been checked already) */
222 if (inode
->i_uid
== current
->fsuid
)
226 if (pa
->e_id
== current
->fsuid
)
230 if (in_group_p(inode
->i_gid
)) {
232 if ((pa
->e_perm
& want
) == want
)
237 if (in_group_p(pa
->e_id
)) {
239 if ((pa
->e_perm
& want
) == want
)
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
)
266 if ((pa
->e_perm
& want
) == want
)
272 * Modify acl when creating a new inode. The caller must ensure the acl is
273 * only referenced once.
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.
280 posix_acl_create_masq(struct posix_acl
*acl
, mode_t
*mode_p
)
282 struct posix_acl_entry
*pa
, *pe
;
283 struct posix_acl_entry
*group_obj
= NULL
, *mask_obj
= NULL
;
284 mode_t mode
= *mode_p
;
287 /* assert(atomic_read(acl->a_refcount) == 1); */
289 FOREACH_ACL_ENTRY(pa
, acl
, pe
) {
292 pa
->e_perm
&= (mode
>> 6) | ~S_IRWXO
;
293 mode
&= (pa
->e_perm
<< 6) | ~S_IRWXU
;
306 pa
->e_perm
&= mode
| ~S_IRWXO
;
307 mode
&= pa
->e_perm
| ~S_IRWXO
;
321 mask_obj
->e_perm
&= (mode
>> 3) | ~S_IRWXO
;
322 mode
&= (mask_obj
->e_perm
<< 3) | ~S_IRWXG
;
326 group_obj
->e_perm
&= (mode
>> 3) | ~S_IRWXO
;
327 mode
&= (group_obj
->e_perm
<< 3) | ~S_IRWXG
;
330 *mode_p
= (*mode_p
& ~S_IRWXUGO
) | mode
;
335 * Modify the ACL for the chmod syscall.
338 posix_acl_chmod_masq(struct posix_acl
*acl
, mode_t mode
)
340 struct posix_acl_entry
*group_obj
= NULL
, *mask_obj
= NULL
;
341 struct posix_acl_entry
*pa
, *pe
;
343 /* assert(atomic_read(acl->a_refcount) == 1); */
345 FOREACH_ACL_ENTRY(pa
, acl
, pe
) {
348 pa
->e_perm
= (mode
& S_IRWXU
) >> 6;
364 pa
->e_perm
= (mode
& S_IRWXO
);
373 mask_obj
->e_perm
= (mode
& S_IRWXG
) >> 3;
377 group_obj
->e_perm
= (mode
& S_IRWXG
) >> 3;