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1/*
2 File: linux/posix_acl.h
3
4 (C) 2002 Andreas Gruenbacher, <a.gruenbacher@computer.org>
5*/
6
7
8#ifndef __LINUX_POSIX_ACL_H
9#define __LINUX_POSIX_ACL_H
10
11#include <linux/bug.h>
12#include <linux/slab.h>
13#include <linux/rcupdate.h>
14
15#define ACL_UNDEFINED_ID (-1)
16
17/* a_type field in acl_user_posix_entry_t */
18#define ACL_TYPE_ACCESS (0x8000)
19#define ACL_TYPE_DEFAULT (0x4000)
20
21/* e_tag entry in struct posix_acl_entry */
22#define ACL_USER_OBJ (0x01)
23#define ACL_USER (0x02)
24#define ACL_GROUP_OBJ (0x04)
25#define ACL_GROUP (0x08)
26#define ACL_MASK (0x10)
27#define ACL_OTHER (0x20)
28
29/* permissions in the e_perm field */
30#define ACL_READ (0x04)
31#define ACL_WRITE (0x02)
32#define ACL_EXECUTE (0x01)
33//#define ACL_ADD (0x08)
34//#define ACL_DELETE (0x10)
35
36struct posix_acl_entry {
37 short e_tag;
38 unsigned short e_perm;
39 unsigned int e_id;
40};
41
42struct posix_acl {
43 union {
44 atomic_t a_refcount;
45 struct rcu_head a_rcu;
46 };
47 unsigned int a_count;
48 struct posix_acl_entry a_entries[0];
49};
50
51#define FOREACH_ACL_ENTRY(pa, acl, pe) \
52 for(pa=(acl)->a_entries, pe=pa+(acl)->a_count; pa<pe; pa++)
53
54
55/*
56 * Duplicate an ACL handle.
57 */
58static inline struct posix_acl *
59posix_acl_dup(struct posix_acl *acl)
60{
61 if (acl)
62 atomic_inc(&acl->a_refcount);
63 return acl;
64}
65
66/*
67 * Free an ACL handle.
68 */
69static inline void
70posix_acl_release(struct posix_acl *acl)
71{
72 if (acl && atomic_dec_and_test(&acl->a_refcount))
73 kfree_rcu(acl, a_rcu);
74}
75
76
77/* posix_acl.c */
78
79extern void posix_acl_init(struct posix_acl *, int);
80extern struct posix_acl *posix_acl_alloc(int, gfp_t);
81extern int posix_acl_valid(const struct posix_acl *);
82extern int posix_acl_permission(struct inode *, const struct posix_acl *, int);
83extern struct posix_acl *posix_acl_from_mode(umode_t, gfp_t);
84extern int posix_acl_equiv_mode(const struct posix_acl *, umode_t *);
85extern int posix_acl_create(struct posix_acl **, gfp_t, umode_t *);
86extern int posix_acl_chmod(struct posix_acl **, gfp_t, umode_t);
87
88extern struct posix_acl *get_posix_acl(struct inode *, int);
89extern int set_posix_acl(struct inode *, int, struct posix_acl *);
90
91#ifdef CONFIG_FS_POSIX_ACL
92static inline struct posix_acl **acl_by_type(struct inode *inode, int type)
93{
94 switch (type) {
95 case ACL_TYPE_ACCESS:
96 return &inode->i_acl;
97 case ACL_TYPE_DEFAULT:
98 return &inode->i_default_acl;
99 default:
100 BUG();
101 }
102}
103
104static inline struct posix_acl *get_cached_acl(struct inode *inode, int type)
105{
106 struct posix_acl **p = acl_by_type(inode, type);
107 struct posix_acl *acl = ACCESS_ONCE(*p);
108 if (acl) {
109 spin_lock(&inode->i_lock);
110 acl = *p;
111 if (acl != ACL_NOT_CACHED)
112 acl = posix_acl_dup(acl);
113 spin_unlock(&inode->i_lock);
114 }
115 return acl;
116}
117
118static inline struct posix_acl *get_cached_acl_rcu(struct inode *inode, int type)
119{
120 return rcu_dereference(*acl_by_type(inode, type));
121}
122
123static inline void set_cached_acl(struct inode *inode,
124 int type,
125 struct posix_acl *acl)
126{
127 struct posix_acl **p = acl_by_type(inode, type);
128 struct posix_acl *old;
129 spin_lock(&inode->i_lock);
130 old = *p;
131 rcu_assign_pointer(*p, posix_acl_dup(acl));
132 spin_unlock(&inode->i_lock);
133 if (old != ACL_NOT_CACHED)
134 posix_acl_release(old);
135}
136
137static inline void forget_cached_acl(struct inode *inode, int type)
138{
139 struct posix_acl **p = acl_by_type(inode, type);
140 struct posix_acl *old;
141 spin_lock(&inode->i_lock);
142 old = *p;
143 *p = ACL_NOT_CACHED;
144 spin_unlock(&inode->i_lock);
145 if (old != ACL_NOT_CACHED)
146 posix_acl_release(old);
147}
148
149static inline void forget_all_cached_acls(struct inode *inode)
150{
151 struct posix_acl *old_access, *old_default;
152 spin_lock(&inode->i_lock);
153 old_access = inode->i_acl;
154 old_default = inode->i_default_acl;
155 inode->i_acl = inode->i_default_acl = ACL_NOT_CACHED;
156 spin_unlock(&inode->i_lock);
157 if (old_access != ACL_NOT_CACHED)
158 posix_acl_release(old_access);
159 if (old_default != ACL_NOT_CACHED)
160 posix_acl_release(old_default);
161}
162#endif
163
164static inline void cache_no_acl(struct inode *inode)
165{
166#ifdef CONFIG_FS_POSIX_ACL
167 inode->i_acl = NULL;
168 inode->i_default_acl = NULL;
169#endif
170}
171
172#endif /* __LINUX_POSIX_ACL_H */