include/linux/xattr.h

/* SPDX-License-Identifier: GPL-2.0 */
/*
  File: linux/xattr.h

  Extended attributes handling.

  Copyright (C) 2001 by Andreas Gruenbacher <a.gruenbacher@computer.org>
  Copyright (c) 2001-2002 Silicon Graphics, Inc.  All Rights Reserved.
  Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com>
*/
#ifndef _LINUX_XATTR_H
#define _LINUX_XATTR_H


#include <linux/slab.h>
#include <linux/types.h>
#include <linux/spinlock.h>
#include <linux/mm.h>
#include <linux/user_namespace.h>
#include <uapi/linux/xattr.h>

struct inode;
struct dentry;

/*
 * struct xattr_handler: When @name is set, match attributes with exactly that
 * name.  When @prefix is set instead, match attributes with that prefix and
 * with a non-empty suffix.
 */
struct xattr_handler {
	const char *name;
	const char *prefix;
	int flags;      /* fs private flags */
	bool (*list)(struct dentry *dentry);
	int (*get)(const struct xattr_handler *, struct dentry *dentry,
		   struct inode *inode, const char *name, void *buffer,
		   size_t size);
	int (*set)(const struct xattr_handler *,
		   struct user_namespace *mnt_userns, struct dentry *dentry,
		   struct inode *inode, const char *name, const void *buffer,
		   size_t size, int flags);
};

const char *xattr_full_name(const struct xattr_handler *, const char *);

struct xattr {
	const char *name;
	void *value;
	size_t value_len;
};

ssize_t __vfs_getxattr(struct dentry *, struct inode *, const char *, void *, size_t);
ssize_t vfs_getxattr(struct user_namespace *, struct dentry *, const char *,
		     void *, size_t);
ssize_t vfs_listxattr(struct dentry *d, char *list, size_t size);
int __vfs_setxattr(struct user_namespace *, struct dentry *, struct inode *,
		   const char *, const void *, size_t, int);
int __vfs_setxattr_noperm(struct user_namespace *, struct dentry *,
			  const char *, const void *, size_t, int);
int __vfs_setxattr_locked(struct user_namespace *, struct dentry *,
			  const char *, const void *, size_t, int,
			  struct inode **);
int vfs_setxattr(struct user_namespace *, struct dentry *, const char *,
		 const void *, size_t, int);
int __vfs_removexattr(struct user_namespace *, struct dentry *, const char *);
int __vfs_removexattr_locked(struct user_namespace *, struct dentry *,
			     const char *, struct inode **);
int vfs_removexattr(struct user_namespace *, struct dentry *, const char *);

ssize_t generic_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size);
ssize_t vfs_getxattr_alloc(struct user_namespace *mnt_userns,
			   struct dentry *dentry, const char *name,
			   char **xattr_value, size_t size, gfp_t flags);

int xattr_supported_namespace(struct inode *inode, const char *prefix);

static inline const char *xattr_prefix(const struct xattr_handler *handler)
{
	return handler->prefix ?: handler->name;
}

struct simple_xattrs {
	struct list_head head;
	spinlock_t lock;
};

struct simple_xattr {
	struct list_head list;
	char *name;
	size_t size;
	char value[];
};

/*
 * initialize the simple_xattrs structure
 */
static inline void simple_xattrs_init(struct simple_xattrs *xattrs)
{
	INIT_LIST_HEAD(&xattrs->head);
	spin_lock_init(&xattrs->lock);
}

/*
 * free all the xattrs
 */
static inline void simple_xattrs_free(struct simple_xattrs *xattrs)
{
	struct simple_xattr *xattr, *node;

	list_for_each_entry_safe(xattr, node, &xattrs->head, list) {
		kfree(xattr->name);
		kvfree(xattr);
	}
}

struct simple_xattr *simple_xattr_alloc(const void *value, size_t size);
int simple_xattr_get(struct simple_xattrs *xattrs, const char *name,
		     void *buffer, size_t size);
int simple_xattr_set(struct simple_xattrs *xattrs, const char *name,
		     const void *value, size_t size, int flags,
		     ssize_t *removed_size);
ssize_t simple_xattr_list(struct inode *inode, struct simple_xattrs *xattrs, char *buffer,
			  size_t size);
void simple_xattr_list_add(struct simple_xattrs *xattrs,
			   struct simple_xattr *new_xattr);

#endif	/* _LINUX_XATTR_H */