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 /* List of all open_how "versions". */
  23 #define XATTR_ARGS_SIZE_VER0    16 /* sizeof first published struct */
  24 #define XATTR_ARGS_SIZE_LATEST  XATTR_ARGS_SIZE_VER0
  25
  26 struct inode;
  27 struct dentry;
  28
  29 static inline bool is_posix_acl_xattr(const char *name)
  30 {
  31         return (strcmp(name, XATTR_NAME_POSIX_ACL_ACCESS) == 0) ||
  32                (strcmp(name, XATTR_NAME_POSIX_ACL_DEFAULT) == 0);
  33 }
  34
  35 /*
  36  * struct xattr_handler: When @name is set, match attributes with exactly that
  37  * name.  When @prefix is set instead, match attributes with that prefix and
  38  * with a non-empty suffix.
  39  */
  40 struct xattr_handler {
  41         const char *name;
  42         const char *prefix;
  43         int flags;      /* fs private flags */
  44         bool (*list)(struct dentry *dentry);
  45         int (*get)(const struct xattr_handler *, struct dentry *dentry,
  46                    struct inode *inode, const char *name, void *buffer,
  47                    size_t size);
  48         int (*set)(const struct xattr_handler *,
  49                    struct mnt_idmap *idmap, struct dentry *dentry,
  50                    struct inode *inode, const char *name, const void *buffer,
  51                    size_t size, int flags);
  52 };
  53
  54 /**
  55  * xattr_handler_can_list - check whether xattr can be listed
  56  * @handler: handler for this type of xattr
  57  * @dentry: dentry whose inode xattr to list
  58  *
  59  * Determine whether the xattr associated with @dentry can be listed given
  60  * @handler.
  61  *
  62  * Return: true if xattr can be listed, false if not.
  63  */
  64 static inline bool xattr_handler_can_list(const struct xattr_handler *handler,
  65                                           struct dentry *dentry)
  66 {
  67         return handler && (!handler->list || handler->list(dentry));
  68 }
  69
  70 const char *xattr_full_name(const struct xattr_handler *, const char *);
  71
  72 struct xattr {
  73         const char *name;
  74         void *value;
  75         size_t value_len;
  76 };
  77
  78 ssize_t __vfs_getxattr(struct dentry *, struct inode *, const char *, void *, size_t);
  79 ssize_t vfs_getxattr(struct mnt_idmap *, struct dentry *, const char *,
  80                      void *, size_t);
  81 ssize_t vfs_listxattr(struct dentry *d, char *list, size_t size);
  82 int __vfs_setxattr(struct mnt_idmap *, struct dentry *, struct inode *,
  83                    const char *, const void *, size_t, int);
  84 int __vfs_setxattr_noperm(struct mnt_idmap *, struct dentry *,
  85                           const char *, const void *, size_t, int);
  86 int __vfs_setxattr_locked(struct mnt_idmap *, struct dentry *,
  87                           const char *, const void *, size_t, int,
  88                           struct inode **);
  89 int vfs_setxattr(struct mnt_idmap *, struct dentry *, const char *,
  90                  const void *, size_t, int);
  91 int __vfs_removexattr(struct mnt_idmap *, struct dentry *, const char *);
  92 int __vfs_removexattr_locked(struct mnt_idmap *, struct dentry *,
  93                              const char *, struct inode **);
  94 int vfs_removexattr(struct mnt_idmap *, struct dentry *, const char *);
  95
  96 ssize_t generic_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size);
  97 int vfs_getxattr_alloc(struct mnt_idmap *idmap,
  98                        struct dentry *dentry, const char *name,
  99                        char **xattr_value, size_t size, gfp_t flags);
 100
 101 int xattr_supports_user_prefix(struct inode *inode);
 102
 103 static inline const char *xattr_prefix(const struct xattr_handler *handler)
 104 {
 105         return handler->prefix ?: handler->name;
 106 }
 107
 108 struct simple_xattrs {
 109         struct rb_root rb_root;
 110         rwlock_t lock;
 111 };
 112
 113 struct simple_xattr {
 114         struct rb_node rb_node;
 115         char *name;
 116         size_t size;
 117         char value[];
 118 };
 119
 120 void simple_xattrs_init(struct simple_xattrs *xattrs);
 121 void simple_xattrs_free(struct simple_xattrs *xattrs, size_t *freed_space);
 122 size_t simple_xattr_space(const char *name, size_t size);
 123 struct simple_xattr *simple_xattr_alloc(const void *value, size_t size);
 124 void simple_xattr_free(struct simple_xattr *xattr);
 125 int simple_xattr_get(struct simple_xattrs *xattrs, const char *name,
 126                      void *buffer, size_t size);
 127 struct simple_xattr *simple_xattr_set(struct simple_xattrs *xattrs,
 128                                       const char *name, const void *value,
 129                                       size_t size, int flags);
 130 ssize_t simple_xattr_list(struct inode *inode, struct simple_xattrs *xattrs,
 131                           char *buffer, size_t size);
 132 void simple_xattr_add(struct simple_xattrs *xattrs,
 133                       struct simple_xattr *new_xattr);
 134 int xattr_list_one(char **buffer, ssize_t *remaining_size, const char *name);
 135
 136 #endif  /* _LINUX_XATTR_H */