include/linux/xattr.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3   File: linux/xattr.h
   4
   5   Extended attributes handling.
   6
   7   Copyright (C) 2001 by Andreas Gruenbacher <a.gruenbacher@computer.org>
   8   Copyright (c) 2001-2002 Silicon Graphics, Inc.  All Rights Reserved.
   9   Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com>
  10 */
  11 #ifndef _LINUX_XATTR_H
  12 #define _LINUX_XATTR_H
  13
  14
  15 #include <linux/slab.h>
  16 #include <linux/types.h>
  17 #include <linux/spinlock.h>
  18 #include <linux/mm.h>
  19 #include <linux/user_namespace.h>
  20 #include <uapi/linux/xattr.h>
  21
  22 struct inode;
  23 struct dentry;
  24
  25 /*
  26  * struct xattr_handler: When @name is set, match attributes with exactly that
  27  * name.  When @prefix is set instead, match attributes with that prefix and
  28  * with a non-empty suffix.
  29  */
  30 struct xattr_handler {
  31         const char *name;
  32         const char *prefix;
  33         int flags;      /* fs private flags */
  34         bool (*list)(struct dentry *dentry);
  35         int (*get)(const struct xattr_handler *, struct dentry *dentry,
  36                    struct inode *inode, const char *name, void *buffer,
  37                    size_t size);
  38         int (*set)(const struct xattr_handler *,
  39                    struct user_namespace *mnt_userns, struct dentry *dentry,
  40                    struct inode *inode, const char *name, const void *buffer,
  41                    size_t size, int flags);
  42 };
  43
  44 const char *xattr_full_name(const struct xattr_handler *, const char *);
  45
  46 struct xattr {
  47         const char *name;
  48         void *value;
  49         size_t value_len;
  50 };
  51
  52 ssize_t __vfs_getxattr(struct dentry *, struct inode *, const char *, void *, size_t);
  53 ssize_t vfs_getxattr(struct user_namespace *, struct dentry *, const char *,
  54                      void *, size_t);
  55 ssize_t vfs_listxattr(struct dentry *d, char *list, size_t size);
  56 int __vfs_setxattr(struct user_namespace *, struct dentry *, struct inode *,
  57                    const char *, const void *, size_t, int);
  58 int __vfs_setxattr_noperm(struct user_namespace *, struct dentry *,
  59                           const char *, const void *, size_t, int);
  60 int __vfs_setxattr_locked(struct user_namespace *, struct dentry *,
  61                           const char *, const void *, size_t, int,
  62                           struct inode **);
  63 int vfs_setxattr(struct user_namespace *, struct dentry *, const char *,
  64                  const void *, size_t, int);
  65 int __vfs_removexattr(struct user_namespace *, struct dentry *, const char *);
  66 int __vfs_removexattr_locked(struct user_namespace *, struct dentry *,
  67                              const char *, struct inode **);
  68 int vfs_removexattr(struct user_namespace *, struct dentry *, const char *);
  69
  70 ssize_t generic_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size);
  71 ssize_t vfs_getxattr_alloc(struct user_namespace *mnt_userns,
  72                            struct dentry *dentry, const char *name,
  73                            char **xattr_value, size_t size, gfp_t flags);
  74
  75 int xattr_supported_namespace(struct inode *inode, const char *prefix);
  76
  77 static inline const char *xattr_prefix(const struct xattr_handler *handler)
  78 {
  79         return handler->prefix ?: handler->name;
  80 }
  81
  82 struct simple_xattrs {
  83         struct list_head head;
  84         spinlock_t lock;
  85 };
  86
  87 struct simple_xattr {
  88         struct list_head list;
  89         char *name;
  90         size_t size;
  91         char value[];
  92 };
  93
  94 /*
  95  * initialize the simple_xattrs structure
  96  */
  97 static inline void simple_xattrs_init(struct simple_xattrs *xattrs)
  98 {
  99         INIT_LIST_HEAD(&xattrs->head);
 100         spin_lock_init(&xattrs->lock);
 101 }
 102
 103 /*
 104  * free all the xattrs
 105  */
 106 static inline void simple_xattrs_free(struct simple_xattrs *xattrs)
 107 {
 108         struct simple_xattr *xattr, *node;
 109
 110         list_for_each_entry_safe(xattr, node, &xattrs->head, list) {
 111                 kfree(xattr->name);
 112                 kvfree(xattr);
 113         }
 114 }
 115
 116 struct simple_xattr *simple_xattr_alloc(const void *value, size_t size);
 117 int simple_xattr_get(struct simple_xattrs *xattrs, const char *name,
 118                      void *buffer, size_t size);
 119 int simple_xattr_set(struct simple_xattrs *xattrs, const char *name,
 120                      const void *value, size_t size, int flags,
 121                      ssize_t *removed_size);
 122 ssize_t simple_xattr_list(struct inode *inode, struct simple_xattrs *xattrs, char *buffer,
 123                           size_t size);
 124 void simple_xattr_list_add(struct simple_xattrs *xattrs,
 125                            struct simple_xattr *new_xattr);
 126
 127 #endif  /* _LINUX_XATTR_H */