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/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
  35struct posix_acl_entry {
  36        short                   e_tag;
  37        unsigned short          e_perm;
  38        unsigned int            e_id;
  39};
  40
  41struct 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 */
  57static inline struct posix_acl *
  58posix_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 */
  68static inline void
  69posix_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
  78extern void posix_acl_init(struct posix_acl *, int);
  79extern struct posix_acl *posix_acl_alloc(int, gfp_t);
  80extern int posix_acl_valid(const struct posix_acl *);
  81extern int posix_acl_permission(struct inode *, const struct posix_acl *, int);
  82extern struct posix_acl *posix_acl_from_mode(umode_t, gfp_t);
  83extern int posix_acl_equiv_mode(const struct posix_acl *, umode_t *);
  84extern int posix_acl_create(struct posix_acl **, gfp_t, umode_t *);
  85extern int posix_acl_chmod(struct posix_acl **, gfp_t, umode_t);
  86
  87extern struct posix_acl *get_posix_acl(struct inode *, int);
  88extern int set_posix_acl(struct inode *, int, struct posix_acl *);
  89
  90#ifdef CONFIG_FS_POSIX_ACL
  91static 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
 103static 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
 117static 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
 122static 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
 136static 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
 148static 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
 163static 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 */
 172