linux/include/linux/posix_acl.h
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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 */
 173
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