
  +   	ˆl–Ü4ý( ©³( 	Å€fàB¦-ÿÄ„dNÏ_†I|¥+ÄÃ ?÷     	/* SPDX-License-Identifier: GPL-2.0 */
/*
 * fscrypt.h: declarations for per-file encryption
 *
 * Filesystems that implement per-file encryption must include this header
 * file.
 *
 * Copyright (C) 2015, Google, Inc.
 *
 * Written by Michael Halcrow, 2015.
 * Modified by Jaegeuk Kim, 2015.
 */
#ifndef _LINUX_FSCRYPT_H
#define _LINUX_FSCRYPT_H

#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <uapi/linux/fscrypt.h>

/*
 * The lengths of all file contents blocks must be divisible by this value.
 * This is needed to ensure that all contents encryption modes will work, as
 * some of the supported modes don't support arbitrarily byte-aligned messages.
 *
 * Since the needed alignment is 16 bytes, most filesystems will meet this
 * requirement naturally, as typical block sizes are powers of 2.  However, if a
 * filesystem can generate arbitrarily byte-aligned block lengths (e.g., via
 * compression), then it will need to pad to this alignment before encryption.
 */
#define FSCRYPT_CONTENTS_ALIGNMENT 16

union fscrypt_policy;
struct fscrypt_info;
struct fs_parameter;
struct seq_file;

struct fscrypt_str {
	unsigned char *name;
	u32 len;
};

struct fscrypt_name {
	const struct qstr *usr_fname;
	struct fscrypt_str disk_name;
	u32 hash;
	u32 minor_hash;
	struct fscrypt_str crypto_buf;
	bool is_nokey_name;
};

#define FSTR_INIT(n, l)		{ .name = n, .len = l }
#define FSTR_TO_QSTR(f)		QSTR_INIT((f)->name, (f)->len)
#define fname_name(p)		((p)->disk_name.name)
#define fname_len(p)		((p)->disk_name.len)

/* Maximum value for the third parameter of fscrypt_operations.set_context(). */
#define FSCRYPT_SET_CONTEXT_MAX_SIZE	40

#ifdef CONFIG_FS_ENCRYPTION

/*
 * If set, the fscrypt bounce page pool won't be allocated (unless another
 * filesystem needs it).  Set this if the filesystem always uses its own bounce
 * pages for writes and therefore won't need the fscrypt bounce page pool.
 */
#define FS_CFLG_OWN_PAGES (1U << 1)

/* Crypto operations for filesystems */
struct fscrypt_operations {

	/* Set of optional flags; see above for allowed flags */
	unsigned int flags;

	/*
	 * If set, this is a filesystem-specific key description prefix that
	 * will be accepted for "logon" keys for v1 fscrypt policies, in
	 * addition to the generic prefix "fscrypt:".  This functionality is
	 * deprecated, so new filesystems shouldn't set this field.
	 */
	const char *key_prefix;

	/*
	 * Get the fscrypt context of the given inode.
	 *
	 * @inode: the inode whose context to get
	 * @ctx: the buffer into which to get the context
	 * @len: length of the @ctx buffer in bytes
	 *
	 * Return: On success, returns the length of the context in bytes; this
	 *	   may be less than @len.  On failure, returns -ENODATA if the
	 *	   inode doesn't have a context, -ERANGE if the context is
	 *	   longer than @len, or another -errno code.
	 */
	int (*get_context)(struct inode *inode, void *ctx, size_t len);

	/*
	 * Set an fscrypt context on the given inode.
	 *
	 * @inode: the inode whose context to set.  The inode won't already have
	 *	   an fscrypt context.
	 * @ctx: the context to set
	 * @len: length of @ctx in bytes (at most FSCRYPT_SET_CONTEXT_MAX_SIZE)
	 * @fs_data: If called from fscrypt_set_context(), this will be the
	 *	     value the filesystem passed to fscrypt_set_context().
	 *	     Otherwise (i.e. when called from
	 *	     FS_IOC_SET_ENCRYPTION_POLICY) this will be NULL.
	 *
	 * i_rwsem will be held for write.
	 *
	 * Return: 0 on success, -errno on failure.
	 */
	int (*set_context)(struct inode *inode, const void *ctx, size_t len,
			   void *fs_data);

	/*
	 * Get the dummy fscrypt policy in use on the filesystem (if any).
	 *
	 * Filesystems only need to implement this function if they support the
	 * test_dummy_encryption mount option.
	 *
	 * Return: A pointer to the dummy fscrypt policy, if the filesystem is
	 *	   mounted with test_dummy_encryption; otherwise NULL.
	 */
	const union fscrypt_policy *(*get_dummy_policy)(struct super_block *sb);

	/*
	 * Ch