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