LXR linux/include/linux/posix

   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
  36struct 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
  48struct 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 */
  64static inline struct posix_acl *
  65posix_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 */
  75static inline void
  76posix_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
  85extern void posix_acl_init(struct posix_acl *, int);
  86extern struct posix_acl *posix_acl_alloc(int, gfp_t);
  87extern int posix_acl_valid(const struct posix_acl *);
  88extern int posix_acl_permission(struct inode *, const struct posix_acl *, int);
  89extern struct posix_acl *posix_acl_from_mode(umode_t, gfp_t);
  90extern int posix_acl_equiv_mode(const struct posix_acl *, umode_t *);
  91extern int posix_acl_create(struct posix_acl **, gfp_t, umode_t *);
  92extern int posix_acl_chmod(struct posix_acl **, gfp_t, umode_t);
  93
  94extern struct posix_acl *get_posix_acl(struct inode *, int);
  95extern int set_posix_acl(struct inode *, int, struct posix_acl *);
  96
  97#ifdef CONFIG_FS_POSIX_ACL
  98static 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
 110static 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
 124static 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
 129static 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
 143static 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
 155static 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
 170static 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 */
 179