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 int posix_acl_valid(const struct posix_acl *);
  77 extern int posix_acl_permission(struct inode *, const struct posix_acl *, int);
  78 extern struct posix_acl *posix_acl_from_mode(umode_t, gfp_t);
  79 extern int posix_acl_equiv_mode(const struct posix_acl *, umode_t *);
  80 extern int posix_acl_create(struct posix_acl **, gfp_t, umode_t *);
  81 extern int posix_acl_chmod(struct posix_acl **, gfp_t, mode_t);
  82
  83 extern struct posix_acl *get_posix_acl(struct inode *, int);
  84 extern int set_posix_acl(struct inode *, int, struct posix_acl *);
  85
  86 #ifdef CONFIG_FS_POSIX_ACL
  87 static inline struct posix_acl *get_cached_acl(struct inode *inode, int type)
  88 {
  89         struct posix_acl **p, *acl;
  90         switch (type) {
  91         case ACL_TYPE_ACCESS:
  92                 p = &inode->i_acl;
  93                 break;
  94         case ACL_TYPE_DEFAULT:
  95                 p = &inode->i_default_acl;
  96                 break;
  97         default:
  98                 return ERR_PTR(-EINVAL);
  99         }
 100         acl = ACCESS_ONCE(*p);
 101         if (acl) {
 102                 spin_lock(&inode->i_lock);
 103                 acl = *p;
 104                 if (acl != ACL_NOT_CACHED)
 105                         acl = posix_acl_dup(acl);
 106                 spin_unlock(&inode->i_lock);
 107         }
 108         return acl;
 109 }
 110
 111 static inline int negative_cached_acl(struct inode *inode, int type)
 112 {
 113         struct posix_acl **p, *acl;
 114         switch (type) {
 115         case ACL_TYPE_ACCESS:
 116                 p = &inode->i_acl;
 117                 break;
 118         case ACL_TYPE_DEFAULT:
 119                 p = &inode->i_default_acl;
 120                 break;
 121         default:
 122                 BUG();
 123         }
 124         acl = ACCESS_ONCE(*p);
 125         if (acl)
 126                 return 0;
 127         return 1;
 128 }
 129
 130 static inline void set_cached_acl(struct inode *inode,
 131                                   int type,
 132                                   struct posix_acl *acl)
 133 {
 134         struct posix_acl *old = NULL;
 135         spin_lock(&inode->i_lock);
 136         switch (type) {
 137         case ACL_TYPE_ACCESS:
 138                 old = inode->i_acl;
 139                 inode->i_acl = posix_acl_dup(acl);
 140                 break;
 141         case ACL_TYPE_DEFAULT:
 142                 old = inode->i_default_acl;
 143                 inode->i_default_acl = posix_acl_dup(acl);
 144                 break;
 145         }
 146         spin_unlock(&inode->i_lock);
 147         if (old != ACL_NOT_CACHED)
 148                 posix_acl_release(old);
 149 }
 150
 151 static inline void forget_cached_acl(struct inode *inode, int type)
 152 {
 153         struct posix_acl *old = NULL;
 154         spin_lock(&inode->i_lock);
 155         switch (type) {
 156         case ACL_TYPE_ACCESS:
 157                 old = inode->i_acl;
 158                 inode->i_acl = ACL_NOT_CACHED;
 159                 break;
 160         case ACL_TYPE_DEFAULT:
 161                 old = inode->i_default_acl;
 162                 inode->i_default_acl = ACL_NOT_CACHED;
 163                 break;
 164         }
 165         spin_unlock(&inode->i_lock);
 166         if (old != ACL_NOT_CACHED)
 167                 posix_acl_release(old);
 168 }
 169
 170 static inline void forget_all_cached_acls(struct inode *inode)
 171 {
 172         struct posix_acl *old_access, *old_default;
 173         spin_lock(&inode->i_lock);
 174         old_access = inode->i_acl;
 175         old_default = inode->i_default_acl;
 176         inode->i_acl = inode->i_default_acl = ACL_NOT_CACHED;
 177         spin_unlock(&inode->i_lock);
 178         if (old_access != ACL_NOT_CACHED)
 179                 posix_acl_release(old_access);
 180         if (old_default != ACL_NOT_CACHED)
 181                 posix_acl_release(old_default);
 182 }
 183 #endif
 184
 185 static inline void cache_no_acl(struct inode *inode)
 186 {
 187 #ifdef CONFIG_FS_POSIX_ACL
 188         inode->i_acl = NULL;
 189         inode->i_default_acl = NULL;
 190 #endif
 191 }
 192
 193 #endif  /* __LINUX_POSIX_ACL_H */