Pileus Git - ~andy/linux/blob - 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/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
  36 struct posix_acl_entry {
  37         short                   e_tag;
  38         unsigned short          e_perm;
  39         union {
  40                 kuid_t          e_uid;
  41                 kgid_t          e_gid;
  42         };
  43 };
  44
  45 struct posix_acl {
  46         union {
  47                 atomic_t                a_refcount;
  48                 struct rcu_head         a_rcu;
  49         };
  50         unsigned int            a_count;
  51         struct posix_acl_entry  a_entries[0];
  52 };
  53
  54 #define FOREACH_ACL_ENTRY(pa, acl, pe) \
  55         for(pa=(acl)->a_entries, pe=pa+(acl)->a_count; pa<pe; pa++)
  56
  57
  58 /*
  59  * Duplicate an ACL handle.
  60  */
  61 static inline struct posix_acl *
  62 posix_acl_dup(struct posix_acl *acl)
  63 {
  64         if (acl)
  65                 atomic_inc(&acl->a_refcount);
  66         return acl;
  67 }
  68
  69 /*
  70  * Free an ACL handle.
  71  */
  72 static inline void
  73 posix_acl_release(struct posix_acl *acl)
  74 {
  75         if (acl && atomic_dec_and_test(&acl->a_refcount))
  76                 kfree_rcu(acl, a_rcu);
  77 }
  78
  79
  80 /* posix_acl.c */
  81
  82 extern void posix_acl_init(struct posix_acl *, int);
  83 extern struct posix_acl *posix_acl_alloc(int, gfp_t);
  84 extern int posix_acl_valid(const struct posix_acl *);
  85 extern int posix_acl_permission(struct inode *, const struct posix_acl *, int);
  86 extern struct posix_acl *posix_acl_from_mode(umode_t, gfp_t);
  87 extern int posix_acl_equiv_mode(const struct posix_acl *, umode_t *);
  88 extern int posix_acl_create(struct posix_acl **, gfp_t, umode_t *);
  89 extern int posix_acl_chmod(struct posix_acl **, gfp_t, umode_t);
  90
  91 extern struct posix_acl *get_posix_acl(struct inode *, int);
  92 extern int set_posix_acl(struct inode *, int, struct posix_acl *);
  93
  94 #ifdef CONFIG_FS_POSIX_ACL
  95 static inline struct posix_acl **acl_by_type(struct inode *inode, int type)
  96 {
  97         switch (type) {
  98         case ACL_TYPE_ACCESS:
  99                 return &inode->i_acl;
 100         case ACL_TYPE_DEFAULT:
 101                 return &inode->i_default_acl;
 102         default:
 103                 BUG();
 104         }
 105 }
 106
 107 static inline struct posix_acl *get_cached_acl(struct inode *inode, int type)
 108 {
 109         struct posix_acl **p = acl_by_type(inode, type);
 110         struct posix_acl *acl = ACCESS_ONCE(*p);
 111         if (acl) {
 112                 spin_lock(&inode->i_lock);
 113                 acl = *p;
 114                 if (acl != ACL_NOT_CACHED)
 115                         acl = posix_acl_dup(acl);
 116                 spin_unlock(&inode->i_lock);
 117         }
 118         return acl;
 119 }
 120
 121 static inline struct posix_acl *get_cached_acl_rcu(struct inode *inode, int type)
 122 {
 123         return rcu_dereference(*acl_by_type(inode, type));
 124 }
 125
 126 static inline void set_cached_acl(struct inode *inode,
 127                                   int type,
 128                                   struct posix_acl *acl)
 129 {
 130         struct posix_acl **p = acl_by_type(inode, type);
 131         struct posix_acl *old;
 132         spin_lock(&inode->i_lock);
 133         old = *p;
 134         rcu_assign_pointer(*p, posix_acl_dup(acl));
 135         spin_unlock(&inode->i_lock);
 136         if (old != ACL_NOT_CACHED)
 137                 posix_acl_release(old);
 138 }
 139
 140 static inline void forget_cached_acl(struct inode *inode, int type)
 141 {
 142         struct posix_acl **p = acl_by_type(inode, type);
 143         struct posix_acl *old;
 144         spin_lock(&inode->i_lock);
 145         old = *p;
 146         *p = ACL_NOT_CACHED;
 147         spin_unlock(&inode->i_lock);
 148         if (old != ACL_NOT_CACHED)
 149                 posix_acl_release(old);
 150 }
 151
 152 static inline void forget_all_cached_acls(struct inode *inode)
 153 {
 154         struct posix_acl *old_access, *old_default;
 155         spin_lock(&inode->i_lock);
 156         old_access = inode->i_acl;
 157         old_default = inode->i_default_acl;
 158         inode->i_acl = inode->i_default_acl = ACL_NOT_CACHED;
 159         spin_unlock(&inode->i_lock);
 160         if (old_access != ACL_NOT_CACHED)
 161                 posix_acl_release(old_access);
 162         if (old_default != ACL_NOT_CACHED)
 163                 posix_acl_release(old_default);
 164 }
 165 #endif
 166
 167 static inline void cache_no_acl(struct inode *inode)
 168 {
 169 #ifdef CONFIG_FS_POSIX_ACL
 170         inode->i_acl = NULL;
 171         inode->i_default_acl = NULL;
 172 #endif
 173 }
 174
 175 #endif  /* __LINUX_POSIX_ACL_H */