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 #ifndef CONFIG_UIDGID_STRICT_TYPE_CHECKS
  43                 unsigned int    e_id;
  44 #endif
  45         };
  46 };
  47
  48 struct posix_acl {
  49         union {
  50                 atomic_t                a_refcount;
  51                 struct rcu_head         a_rcu;
  52         };
  53         unsigned int            a_count;
  54         struct posix_acl_entry  a_entries[0];
  55 };
  56
  57 #define FOREACH_ACL_ENTRY(pa, acl, pe) \
  58         for(pa=(acl)->a_entries, pe=pa+(acl)->a_count; pa<pe; pa++)
  59
  60
  61 /*
  62  * Duplicate an ACL handle.
  63  */
  64 static inline struct posix_acl *
  65 posix_acl_dup(struct posix_acl *acl)
  66 {
  67         if (acl)
  68                 atomic_inc(&acl->a_refcount);
  69         return acl;
  70 }
  71
  72 /*
  73  * Free an ACL handle.
  74  */
  75 static inline void
  76 posix_acl_release(struct posix_acl *acl)
  77 {
  78         if (acl && atomic_dec_and_test(&acl->a_refcount))
  79                 kfree_rcu(acl, a_rcu);
  80 }
  81
  82
  83 /* posix_acl.c */
  84
  85 extern void posix_acl_init(struct posix_acl *, int);
  86 extern struct posix_acl *posix_acl_alloc(int, gfp_t);
  87 extern int posix_acl_valid(const struct posix_acl *);
  88 extern int posix_acl_permission(struct inode *, const struct posix_acl *, int);
  89 extern struct posix_acl *posix_acl_from_mode(umode_t, gfp_t);
  90 extern int posix_acl_equiv_mode(const struct posix_acl *, umode_t *);
  91 extern int posix_acl_create(struct posix_acl **, gfp_t, umode_t *);
  92 extern int posix_acl_chmod(struct posix_acl **, gfp_t, umode_t);
  93
  94 extern struct posix_acl *get_posix_acl(struct inode *, int);
  95 extern int set_posix_acl(struct inode *, int, struct posix_acl *);
  96
  97 #ifdef CONFIG_FS_POSIX_ACL
  98 static inline struct posix_acl **acl_by_type(struct inode *inode, int type)
  99 {
 100         switch (type) {
 101         case ACL_TYPE_ACCESS:
 102                 return &inode->i_acl;
 103         case ACL_TYPE_DEFAULT:
 104                 return &inode->i_default_acl;
 105         default:
 106                 BUG();
 107         }
 108 }
 109
 110 static inline struct posix_acl *get_cached_acl(struct inode *inode, int type)
 111 {
 112         struct posix_acl **p = acl_by_type(inode, type);
 113         struct posix_acl *acl = ACCESS_ONCE(*p);
 114         if (acl) {
 115                 spin_lock(&inode->i_lock);
 116                 acl = *p;
 117                 if (acl != ACL_NOT_CACHED)
 118                         acl = posix_acl_dup(acl);
 119                 spin_unlock(&inode->i_lock);
 120         }
 121         return acl;
 122 }
 123
 124 static inline struct posix_acl *get_cached_acl_rcu(struct inode *inode, int type)
 125 {
 126         return rcu_dereference(*acl_by_type(inode, type));
 127 }
 128
 129 static inline void set_cached_acl(struct inode *inode,
 130                                   int type,
 131                                   struct posix_acl *acl)
 132 {
 133         struct posix_acl **p = acl_by_type(inode, type);
 134         struct posix_acl *old;
 135         spin_lock(&inode->i_lock);
 136         old = *p;
 137         rcu_assign_pointer(*p, posix_acl_dup(acl));
 138         spin_unlock(&inode->i_lock);
 139         if (old != ACL_NOT_CACHED)
 140                 posix_acl_release(old);
 141 }
 142
 143 static inline void forget_cached_acl(struct inode *inode, int type)
 144 {
 145         struct posix_acl **p = acl_by_type(inode, type);
 146         struct posix_acl *old;
 147         spin_lock(&inode->i_lock);
 148         old = *p;
 149         *p = ACL_NOT_CACHED;
 150         spin_unlock(&inode->i_lock);
 151         if (old != ACL_NOT_CACHED)
 152                 posix_acl_release(old);
 153 }
 154
 155 static inline void forget_all_cached_acls(struct inode *inode)
 156 {
 157         struct posix_acl *old_access, *old_default;
 158         spin_lock(&inode->i_lock);
 159         old_access = inode->i_acl;
 160         old_default = inode->i_default_acl;
 161         inode->i_acl = inode->i_default_acl = ACL_NOT_CACHED;
 162         spin_unlock(&inode->i_lock);
 163         if (old_access != ACL_NOT_CACHED)
 164                 posix_acl_release(old_access);
 165         if (old_default != ACL_NOT_CACHED)
 166                 posix_acl_release(old_default);
 167 }
 168 #endif
 169
 170 static inline void cache_no_acl(struct inode *inode)
 171 {
 172 #ifdef CONFIG_FS_POSIX_ACL
 173         inode->i_acl = NULL;
 174         inode->i_default_acl = NULL;
 175 #endif
 176 }
 177
 178 #endif  /* __LINUX_POSIX_ACL_H */