include/linux/posix_acl.h

   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/slab.h>
  12
  13 #define ACL_UNDEFINED_ID        (-1)
  14
  15 /* a_type field in acl_user_posix_entry_t */
  16 #define ACL_TYPE_ACCESS         (0x8000)
  17 #define ACL_TYPE_DEFAULT        (0x4000)
  18
  19 /* e_tag entry in struct posix_acl_entry */
  20 #define ACL_USER_OBJ            (0x01)
  21 #define ACL_USER                (0x02)
  22 #define ACL_GROUP_OBJ           (0x04)
  23 #define ACL_GROUP               (0x08)
  24 #define ACL_MASK                (0x10)
  25 #define ACL_OTHER               (0x20)
  26
  27 /* permissions in the e_perm field */
  28 #define ACL_READ                (0x04)
  29 #define ACL_WRITE               (0x02)
  30 #define ACL_EXECUTE             (0x01)
  31 //#define ACL_ADD               (0x08)
  32 //#define ACL_DELETE            (0x10)
  33
  34 struct posix_acl_entry {
  35         short                   e_tag;
  36         unsigned short          e_perm;
  37         unsigned int            e_id;
  38 };
  39
  40 struct posix_acl {
  41         atomic_t                a_refcount;
  42         unsigned int            a_count;
  43         struct posix_acl_entry  a_entries[0];
  44 };
  45
  46 #define FOREACH_ACL_ENTRY(pa, acl, pe) \
  47         for(pa=(acl)->a_entries, pe=pa+(acl)->a_count; pa<pe; pa++)
  48
  49
  50 /*
  51  * Duplicate an ACL handle.
  52  */
  53 static inline struct posix_acl *
  54 posix_acl_dup(struct posix_acl *acl)
  55 {
  56         if (acl)
  57                 atomic_inc(&acl->a_refcount);
  58         return acl;
  59 }
  60
  61 /*
  62  * Free an ACL handle.
  63  */
  64 static inline void
  65 posix_acl_release(struct posix_acl *acl)
  66 {
  67         if (acl && atomic_dec_and_test(&acl->a_refcount))
  68                 kfree(acl);
  69 }
  70
  71
  72 /* posix_acl.c */
  73
  74 extern void posix_acl_init(struct posix_acl *, int);
  75 extern struct posix_acl *posix_acl_alloc(int, gfp_t);
  76 extern struct posix_acl *posix_acl_clone(const struct posix_acl *, gfp_t);
  77 extern int posix_acl_valid(const struct posix_acl *);
  78 extern int posix_acl_permission(struct inode *, const struct posix_acl *, int);
  79 extern struct posix_acl *posix_acl_from_mode(mode_t, gfp_t);
  80 extern int posix_acl_equiv_mode(const struct posix_acl *, mode_t *);
  81 extern int posix_acl_create_masq(struct posix_acl *, mode_t *);
  82 extern int posix_acl_chmod_masq(struct posix_acl *, mode_t);
  83
  84 extern struct posix_acl *get_posix_acl(struct inode *, int);
  85 extern int set_posix_acl(struct inode *, int, struct posix_acl *);
  86
  87 #ifdef CONFIG_FS_POSIX_ACL
  88 static inline struct posix_acl *get_cached_acl(struct inode *inode, int type)
  89 {
  90         struct posix_acl **p, *acl;
  91         switch (type) {
  92         case ACL_TYPE_ACCESS:
  93                 p = &inode->i_acl;
  94                 break;
  95         case ACL_TYPE_DEFAULT:
  96                 p = &inode->i_default_acl;
  97                 break;
  98         default:
  99                 return ERR_PTR(-EINVAL);
 100         }
 101         acl = ACCESS_ONCE(*p);
 102         if (acl) {
 103                 spin_lock(&inode->i_lock);
 104                 acl = *p;
 105                 if (acl != ACL_NOT_CACHED)
 106                         acl = posix_acl_dup(acl);
 107                 spin_unlock(&inode->i_lock);
 108         }
 109         return acl;
 110 }
 111
 112 static inline int negative_cached_acl(struct inode *inode, int type)
 113 {
 114         struct posix_acl **p, *acl;
 115         switch (type) {
 116         case ACL_TYPE_ACCESS:
 117                 p = &inode->i_acl;
 118                 break;
 119         case ACL_TYPE_DEFAULT:
 120                 p = &inode->i_default_acl;
 121                 break;
 122         default:
 123                 BUG();
 124         }
 125         acl = ACCESS_ONCE(*p);
 126         if (acl)
 127                 return 0;
 128         return 1;
 129 }
 130
 131 static inline void set_cached_acl(struct inode *inode,
 132                                   int type,
 133                                   struct posix_acl *acl)
 134 {
 135         struct posix_acl *old = NULL;
 136         spin_lock(&inode->i_lock);
 137         switch (type) {
 138         case ACL_TYPE_ACCESS:
 139                 old = inode->i_acl;
 140                 inode->i_acl = posix_acl_dup(acl);
 141                 break;
 142         case ACL_TYPE_DEFAULT:
 143                 old = inode->i_default_acl;
 144                 inode->i_default_acl = posix_acl_dup(acl);
 145                 break;
 146         }
 147         spin_unlock(&inode->i_lock);
 148         if (old != ACL_NOT_CACHED)
 149                 posix_acl_release(old);
 150 }
 151
 152 static inline void forget_cached_acl(struct inode *inode, int type)
 153 {
 154         struct posix_acl *old = NULL;
 155         spin_lock(&inode->i_lock);
 156         switch (type) {
 157         case ACL_TYPE_ACCESS:
 158                 old = inode->i_acl;
 159                 inode->i_acl = ACL_NOT_CACHED;
 160                 break;
 161         case ACL_TYPE_DEFAULT:
 162                 old = inode->i_default_acl;
 163                 inode->i_default_acl = ACL_NOT_CACHED;
 164                 break;
 165         }
 166         spin_unlock(&inode->i_lock);
 167         if (old != ACL_NOT_CACHED)
 168                 posix_acl_release(old);
 169 }
 170
 171 static inline void forget_all_cached_acls(struct inode *inode)
 172 {
 173         struct posix_acl *old_access, *old_default;
 174         spin_lock(&inode->i_lock);
 175         old_access = inode->i_acl;
 176         old_default = inode->i_default_acl;
 177         inode->i_acl = inode->i_default_acl = ACL_NOT_CACHED;
 178         spin_unlock(&inode->i_lock);
 179         if (old_access != ACL_NOT_CACHED)
 180                 posix_acl_release(old_access);
 181         if (old_default != ACL_NOT_CACHED)
 182                 posix_acl_release(old_default);
 183 }
 184 #endif
 185
 186 static inline void cache_no_acl(struct inode *inode)
 187 {
 188 #ifdef CONFIG_FS_POSIX_ACL
 189         inode->i_acl = NULL;
 190         inode->i_default_acl = NULL;
 191 #endif
 192 }
 193
 194 #endif  /* __LINUX_POSIX_ACL_H */