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         unsigned int            e_id;
  40 };
  41
  42 struct 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  */
  58 static inline struct posix_acl *
  59 posix_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  */
  69 static inline void
  70 posix_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
  79 extern void posix_acl_init(struct posix_acl *, int);
  80 extern struct posix_acl *posix_acl_alloc(int, gfp_t);
  81 extern int posix_acl_valid(const struct posix_acl *);
  82 extern int posix_acl_permission(struct inode *, const struct posix_acl *, int);
  83 extern struct posix_acl *posix_acl_from_mode(umode_t, gfp_t);
  84 extern int posix_acl_equiv_mode(const struct posix_acl *, umode_t *);
  85 extern int posix_acl_create(struct posix_acl **, gfp_t, umode_t *);
  86 extern int posix_acl_chmod(struct posix_acl **, gfp_t, umode_t);
  87
  88 extern struct posix_acl *get_posix_acl(struct inode *, int);
  89 extern int set_posix_acl(struct inode *, int, struct posix_acl *);
  90
  91 #ifdef CONFIG_FS_POSIX_ACL
  92 static 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
 104 static 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
 118 static 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
 123 static 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
 137 static 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
 149 static 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
 164 static 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 */