ext4 crypto: migrate into vfs's crypto engine

	  extended attributes for file security labels, say N.

config EXT4_ENCRYPTION

	tristate "Ext4 Encryption"

	bool "Ext4 Encryption"

	depends on EXT4_FS

	select CRYPTO_AES

	select CRYPTO_CBC

	select CRYPTO_ECB

	select CRYPTO_XTS

	select CRYPTO_CTS

	select CRYPTO_CTR

	select CRYPTO_SHA256

	select KEYS

	select ENCRYPTED_KEYS

	select FS_ENCRYPTION

	help

	  Enable encryption of ext4 files and directories.  This

	  feature is similar to ecryptfs, but it is more memory

ext4-$(CONFIG_EXT4_FS_POSIX_ACL)	+= acl.o

ext4-$(CONFIG_EXT4_FS_SECURITY)		+= xattr_security.o

ext4-$(CONFIG_EXT4_FS_ENCRYPTION)	+= crypto_policy.o crypto.o \

		crypto_key.o crypto_fname.o

/*

 * linux/fs/ext4/crypto.c

 *

 * Copyright (C) 2015, Google, Inc.

 *

 * This contains encryption functions for ext4

 *

 * Written by Michael Halcrow, 2014.

 *

 * Filename encryption additions

 *	Uday Savagaonkar, 2014

 * Encryption policy handling additions

 *	Ildar Muslukhov, 2014

 *

 * This has not yet undergone a rigorous security audit.

 *

 * The usage of AES-XTS should conform to recommendations in NIST

 * Special Publication 800-38E and IEEE P1619/D16.

 */

#include <crypto/skcipher.h>

#include <keys/user-type.h>

#include <keys/encrypted-type.h>

#include <linux/ecryptfs.h>

#include <linux/gfp.h>

#include <linux/kernel.h>

#include <linux/key.h>

#include <linux/list.h>

#include <linux/mempool.h>

#include <linux/module.h>

#include <linux/mutex.h>

#include <linux/random.h>

#include <linux/scatterlist.h>

#include <linux/spinlock_types.h>

#include <linux/namei.h>

#include "ext4_extents.h"

#include "xattr.h"

/* Encryption added and removed here! (L: */

static unsigned int num_prealloc_crypto_pages = 32;

static unsigned int num_prealloc_crypto_ctxs = 128;

module_param(num_prealloc_crypto_pages, uint, 0444);

MODULE_PARM_DESC(num_prealloc_crypto_pages,

		 "Number of crypto pages to preallocate");

module_param(num_prealloc_crypto_ctxs, uint, 0444);

MODULE_PARM_DESC(num_prealloc_crypto_ctxs,

		 "Number of crypto contexts to preallocate");

static mempool_t *ext4_bounce_page_pool;

static LIST_HEAD(ext4_free_crypto_ctxs);

static DEFINE_SPINLOCK(ext4_crypto_ctx_lock);

static struct kmem_cache *ext4_crypto_ctx_cachep;

struct kmem_cache *ext4_crypt_info_cachep;

/**

 * ext4_release_crypto_ctx() - Releases an encryption context

 * @ctx: The encryption context to release.

 *

 * If the encryption context was allocated from the pre-allocated pool, returns

 * it to that pool. Else, frees it.

 *

 * If there's a bounce page in the context, this frees that.

 */

void ext4_release_crypto_ctx(struct ext4_crypto_ctx *ctx)

{

	unsigned long flags;

	if (ctx->flags & EXT4_WRITE_PATH_FL && ctx->w.bounce_page)

		mempool_free(ctx->w.bounce_page, ext4_bounce_page_pool);

	ctx->w.bounce_page = NULL;

	ctx->w.control_page = NULL;

	if (ctx->flags & EXT4_CTX_REQUIRES_FREE_ENCRYPT_FL) {

		kmem_cache_free(ext4_crypto_ctx_cachep, ctx);

	} else {

		spin_lock_irqsave(&ext4_crypto_ctx_lock, flags);

		list_add(&ctx->free_list, &ext4_free_crypto_ctxs);

		spin_unlock_irqrestore(&ext4_crypto_ctx_lock, flags);

	}

}

/**

 * ext4_get_crypto_ctx() - Gets an encryption context

 * @inode:       The inode for which we are doing the crypto

 *

 * Allocates and initializes an encryption context.

 *

 * Return: An allocated and initialized encryption context on success; error

 * value or NULL otherwise.

 */

struct ext4_crypto_ctx *ext4_get_crypto_ctx(struct inode *inode,

					    gfp_t gfp_flags)

{

	struct ext4_crypto_ctx *ctx = NULL;

	int res = 0;

	unsigned long flags;

	struct ext4_crypt_info *ci = EXT4_I(inode)->i_crypt_info;

	if (ci == NULL)

		return ERR_PTR(-ENOKEY);

	/*

	 * We first try getting the ctx from a free list because in

	 * the common case the ctx will have an allocated and

	 * initialized crypto tfm, so it's probably a worthwhile

	 * optimization. For the bounce page, we first try getting it

	 * from the kernel allocator because that's just about as fast

	 * as getting it from a list and because a cache of free pages

	 * should generally be a "last resort" option for a filesystem

	 * to be able to do its job.

	 */

	spin_lock_irqsave(&ext4_crypto_ctx_lock, flags);

	ctx = list_first_entry_or_null(&ext4_free_crypto_ctxs,

				       struct ext4_crypto_ctx, free_list);

	if (ctx)

		list_del(&ctx->free_list);

	spin_unlock_irqrestore(&ext4_crypto_ctx_lock, flags);

	if (!ctx) {

		ctx = kmem_cache_zalloc(ext4_crypto_ctx_cachep, gfp_flags);

		if (!ctx) {

			res = -ENOMEM;

			goto out;

		}

		ctx->flags |= EXT4_CTX_REQUIRES_FREE_ENCRYPT_FL;

	} else {

		ctx->flags &= ~EXT4_CTX_REQUIRES_FREE_ENCRYPT_FL;

	}

	ctx->flags &= ~EXT4_WRITE_PATH_FL;

out:

	if (res) {

		if (!IS_ERR_OR_NULL(ctx))

			ext4_release_crypto_ctx(ctx);

		ctx = ERR_PTR(res);

	}

	return ctx;

}

struct workqueue_struct *ext4_read_workqueue;

static DEFINE_MUTEX(crypto_init);

/**

 * ext4_exit_crypto() - Shutdown the ext4 encryption system

 */

void ext4_exit_crypto(void)

{

	struct ext4_crypto_ctx *pos, *n;

	list_for_each_entry_safe(pos, n, &ext4_free_crypto_ctxs, free_list)

		kmem_cache_free(ext4_crypto_ctx_cachep, pos);

	INIT_LIST_HEAD(&ext4_free_crypto_ctxs);

	if (ext4_bounce_page_pool)

		mempool_destroy(ext4_bounce_page_pool);

	ext4_bounce_page_pool = NULL;

	if (ext4_read_workqueue)

		destroy_workqueue(ext4_read_workqueue);

	ext4_read_workqueue = NULL;

	if (ext4_crypto_ctx_cachep)

		kmem_cache_destroy(ext4_crypto_ctx_cachep);

	ext4_crypto_ctx_cachep = NULL;

	if (ext4_crypt_info_cachep)

		kmem_cache_destroy(ext4_crypt_info_cachep);

	ext4_crypt_info_cachep = NULL;

}

/**

 * ext4_init_crypto() - Set up for ext4 encryption.

 *

 * We only call this when we start accessing encrypted files, since it

 * results in memory getting allocated that wouldn't otherwise be used.

 *

 * Return: Zero on success, non-zero otherwise.

 */

int ext4_init_crypto(void)

{

	int i, res = -ENOMEM;

	mutex_lock(&crypto_init);

	if (ext4_read_workqueue)

		goto already_initialized;

	ext4_read_workqueue = alloc_workqueue("ext4_crypto", WQ_HIGHPRI, 0);

	if (!ext4_read_workqueue)

		goto fail;

	ext4_crypto_ctx_cachep = KMEM_CACHE(ext4_crypto_ctx,

					    SLAB_RECLAIM_ACCOUNT);

	if (!ext4_crypto_ctx_cachep)

		goto fail;

	ext4_crypt_info_cachep = KMEM_CACHE(ext4_crypt_info,

					    SLAB_RECLAIM_ACCOUNT);

	if (!ext4_crypt_info_cachep)

		goto fail;

	for (i = 0; i < num_prealloc_crypto_ctxs; i++) {

		struct ext4_crypto_ctx *ctx;

		ctx = kmem_cache_zalloc(ext4_crypto_ctx_cachep, GFP_NOFS);

		if (!ctx) {

			res = -ENOMEM;

			goto fail;

		}

		list_add(&ctx->free_list, &ext4_free_crypto_ctxs);

	}

	ext4_bounce_page_pool =

		mempool_create_page_pool(num_prealloc_crypto_pages, 0);

	if (!ext4_bounce_page_pool) {

		res = -ENOMEM;

		goto fail;

	}

already_initialized:

	mutex_unlock(&crypto_init);

	return 0;

fail:

	ext4_exit_crypto();

	mutex_unlock(&crypto_init);

	return res;

}

void ext4_restore_control_page(struct page *data_page)

{

	struct ext4_crypto_ctx *ctx =

		(struct ext4_crypto_ctx *)page_private(data_page);

	set_page_private(data_page, (unsigned long)NULL);

	ClearPagePrivate(data_page);

	unlock_page(data_page);

	ext4_release_crypto_ctx(ctx);

}

/**

 * ext4_crypt_complete() - The completion callback for page encryption

 * @req: The asynchronous encryption request context

 * @res: The result of the encryption operation

 */

static void ext4_crypt_complete(struct crypto_async_request *req, int res)

{

	struct ext4_completion_result *ecr = req->data;

	if (res == -EINPROGRESS)

		return;

	ecr->res = res;

	complete(&ecr->completion);

}

typedef enum {

	EXT4_DECRYPT = 0,

	EXT4_ENCRYPT,

} ext4_direction_t;

static int ext4_page_crypto(struct inode *inode,

			    ext4_direction_t rw,

			    pgoff_t index,

			    struct page *src_page,

			    struct page *dest_page,

			    gfp_t gfp_flags)

{

	u8 xts_tweak[EXT4_XTS_TWEAK_SIZE];

	struct skcipher_request *req = NULL;

	DECLARE_EXT4_COMPLETION_RESULT(ecr);

	struct scatterlist dst, src;

	struct ext4_crypt_info *ci = EXT4_I(inode)->i_crypt_info;

	struct crypto_skcipher *tfm = ci->ci_ctfm;

	int res = 0;

	req = skcipher_request_alloc(tfm, gfp_flags);

	if (!req) {

		printk_ratelimited(KERN_ERR

				   "%s: crypto_request_alloc() failed\n",

				   __func__);

		return -ENOMEM;

	}

	skcipher_request_set_callback(

		req, CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,

		ext4_crypt_complete, &ecr);

	BUILD_BUG_ON(EXT4_XTS_TWEAK_SIZE < sizeof(index));

	memcpy(xts_tweak, &index, sizeof(index));

	memset(&xts_tweak[sizeof(index)], 0,

	       EXT4_XTS_TWEAK_SIZE - sizeof(index));

	sg_init_table(&dst, 1);

	sg_set_page(&dst, dest_page, PAGE_SIZE, 0);

	sg_init_table(&src, 1);

	sg_set_page(&src, src_page, PAGE_SIZE, 0);

	skcipher_request_set_crypt(req, &src, &dst, PAGE_SIZE,

				   xts_tweak);

	if (rw == EXT4_DECRYPT)

		res = crypto_skcipher_decrypt(req);

	else

		res = crypto_skcipher_encrypt(req);

	if (res == -EINPROGRESS || res == -EBUSY) {

		wait_for_completion(&ecr.completion);

		res = ecr.res;

	}

	skcipher_request_free(req);

	if (res) {

		printk_ratelimited(

			KERN_ERR

			"%s: crypto_skcipher_encrypt() returned %d\n",

			__func__, res);

		return res;

	}

	return 0;

}

static struct page *alloc_bounce_page(struct ext4_crypto_ctx *ctx,

				      gfp_t gfp_flags)

{

	ctx->w.bounce_page = mempool_alloc(ext4_bounce_page_pool, gfp_flags);

	if (ctx->w.bounce_page == NULL)

		return ERR_PTR(-ENOMEM);

	ctx->flags |= EXT4_WRITE_PATH_FL;

	return ctx->w.bounce_page;

}

/**

 * ext4_encrypt() - Encrypts a page

 * @inode:          The inode for which the encryption should take place

 * @plaintext_page: The page to encrypt. Must be locked.

 *

 * Allocates a ciphertext page and encrypts plaintext_page into it using the ctx

 * encryption context.

 *

 * Called on the page write path.  The caller must call

 * ext4_restore_control_page() on the returned ciphertext page to

 * release the bounce buffer and the encryption context.

 *

 * Return: An allocated page with the encrypted content on success. Else, an

 * error value or NULL.

 */

struct page *ext4_encrypt(struct inode *inode,

			  struct page *plaintext_page,

			  gfp_t gfp_flags)

{

	struct ext4_crypto_ctx *ctx;

	struct page *ciphertext_page = NULL;

	int err;

	BUG_ON(!PageLocked(plaintext_page));

	ctx = ext4_get_crypto_ctx(inode, gfp_flags);

	if (IS_ERR(ctx))

		return (struct page *) ctx;

	/* The encryption operation will require a bounce page. */

	ciphertext_page = alloc_bounce_page(ctx, gfp_flags);

	if (IS_ERR(ciphertext_page))

		goto errout;

	ctx->w.control_page = plaintext_page;

	err = ext4_page_crypto(inode, EXT4_ENCRYPT, plaintext_page->index,

			       plaintext_page, ciphertext_page, gfp_flags);

	if (err) {

		ciphertext_page = ERR_PTR(err);

	errout:

		ext4_release_crypto_ctx(ctx);

		return ciphertext_page;

	}

	SetPagePrivate(ciphertext_page);

	set_page_private(ciphertext_page, (unsigned long)ctx);

	lock_page(ciphertext_page);

	return ciphertext_page;

}

/**

 * ext4_decrypt() - Decrypts a page in-place

 * @ctx:  The encryption context.

 * @page: The page to decrypt. Must be locked.

 *

 * Decrypts page in-place using the ctx encryption context.

 *

 * Called from the read completion callback.

 *

 * Return: Zero on success, non-zero otherwise.

 */

int ext4_decrypt(struct page *page)

{

	BUG_ON(!PageLocked(page));

	return ext4_page_crypto(page->mapping->host, EXT4_DECRYPT,

				page->index, page, page, GFP_NOFS);

}

int ext4_encrypted_zeroout(struct inode *inode, ext4_lblk_t lblk,

			   ext4_fsblk_t pblk, ext4_lblk_t len)

{

	struct ext4_crypto_ctx	*ctx;

	struct page		*ciphertext_page = NULL;

	struct bio		*bio;

	int			ret, err = 0;

#if 0

	ext4_msg(inode->i_sb, KERN_CRIT,

		 "ext4_encrypted_zeroout ino %lu lblk %u len %u",

		 (unsigned long) inode->i_ino, lblk, len);

#endif

	BUG_ON(inode->i_sb->s_blocksize != PAGE_SIZE);

	ctx = ext4_get_crypto_ctx(inode, GFP_NOFS);

	if (IS_ERR(ctx))

		return PTR_ERR(ctx);

	ciphertext_page = alloc_bounce_page(ctx, GFP_NOWAIT);

	if (IS_ERR(ciphertext_page)) {

		err = PTR_ERR(ciphertext_page);

		goto errout;

	}

	while (len--) {

		err = ext4_page_crypto(inode, EXT4_ENCRYPT, lblk,

				       ZERO_PAGE(0), ciphertext_page,

				       GFP_NOFS);

		if (err)

			goto errout;

		bio = bio_alloc(GFP_NOWAIT, 1);

		if (!bio) {

			err = -ENOMEM;

			goto errout;

		}

		bio->bi_bdev = inode->i_sb->s_bdev;

		bio->bi_iter.bi_sector =

			pblk << (inode->i_sb->s_blocksize_bits - 9);

		ret = bio_add_page(bio, ciphertext_page,

				   inode->i_sb->s_blocksize, 0);

		if (ret != inode->i_sb->s_blocksize) {

			/* should never happen! */

			ext4_msg(inode->i_sb, KERN_ERR,

				 "bio_add_page failed: %d", ret);

			WARN_ON(1);

			bio_put(bio);

			err = -EIO;

			goto errout;

		}

		err = submit_bio_wait(WRITE, bio);

		if ((err == 0) && bio->bi_error)

			err = -EIO;

		bio_put(bio);

		if (err)

			goto errout;

		lblk++; pblk++;

	}

	err = 0;

errout:

	ext4_release_crypto_ctx(ctx);

	return err;

}

bool ext4_valid_contents_enc_mode(uint32_t mode)

{

	return (mode == EXT4_ENCRYPTION_MODE_AES_256_XTS);

}

/**

 * ext4_validate_encryption_key_size() - Validate the encryption key size

 * @mode: The key mode.

 * @size: The key size to validate.

 *

 * Return: The validated key size for @mode. Zero if invalid.

 */

uint32_t ext4_validate_encryption_key_size(uint32_t mode, uint32_t size)

{

	if (size == ext4_encryption_key_size(mode))

		return size;

	return 0;

}

/*

 * Validate dentries for encrypted directories to make sure we aren't

 * potentially caching stale data after a key has been added or

 * removed.

 */

static int ext4_d_revalidate(struct dentry *dentry, unsigned int flags)

{

	struct dentry *dir;

	struct ext4_crypt_info *ci;

	int dir_has_key, cached_with_key;

	if (flags & LOOKUP_RCU)

		return -ECHILD;

	dir = dget_parent(dentry);

	if (!ext4_encrypted_inode(d_inode(dir))) {

		dput(dir);

		return 0;

	}

	ci = EXT4_I(d_inode(dir))->i_crypt_info;

	if (ci && ci->ci_keyring_key &&

	    (ci->ci_keyring_key->flags & ((1 << KEY_FLAG_INVALIDATED) |

					  (1 << KEY_FLAG_REVOKED) |

					  (1 << KEY_FLAG_DEAD))))

		ci = NULL;

	/* this should eventually be an flag in d_flags */

	cached_with_key = dentry->d_fsdata != NULL;

	dir_has_key = (ci != NULL);

	dput(dir);

	/*

	 * If the dentry was cached without the key, and it is a

	 * negative dentry, it might be a valid name.  We can't check

	 * if the key has since been made available due to locking

	 * reasons, so we fail the validation so ext4_lookup() can do

	 * this check.

	 *

	 * We also fail the validation if the dentry was created with

	 * the key present, but we no longer have the key, or vice versa.

	 */

	if ((!cached_with_key && d_is_negative(dentry)) ||

	    (!cached_with_key && dir_has_key) ||

	    (cached_with_key && !dir_has_key)) {

#if 0				/* Revalidation debug */

		char buf[80];

		char *cp = simple_dname(dentry, buf, sizeof(buf));

		if (IS_ERR(cp))

			cp = (char *) "???";

		pr_err("revalidate: %s %p %d %d %d\n", cp, dentry->d_fsdata,

		       cached_with_key, d_is_negative(dentry),

		       dir_has_key);

#endif

		return 0;

	}

	return 1;

}

const struct dentry_operations ext4_encrypted_d_ops = {

	.d_revalidate = ext4_d_revalidate,

};

/*

 * linux/fs/ext4/crypto_key.c

 *

 * Copyright (C) 2015, Google, Inc.

 *

 * This contains encryption key functions for ext4

 *

 * Written by Michael Halcrow, Ildar Muslukhov, and Uday Savagaonkar, 2015.

 */

#include <crypto/skcipher.h>

#include <keys/encrypted-type.h>

#include <keys/user-type.h>

#include <linux/random.h>

#include <linux/scatterlist.h>

#include <uapi/linux/keyctl.h>

#include "ext4.h"

#include "xattr.h"

static void derive_crypt_complete(struct crypto_async_request *req, int rc)

{

	struct ext4_completion_result *ecr = req->data;

	if (rc == -EINPROGRESS)

		return;

	ecr->res = rc;

	complete(&ecr->completion);

}

/**

 * ext4_derive_key_aes() - Derive a key using AES-128-ECB

 * @deriving_key: Encryption key used for derivation.

 * @source_key:   Source key to which to apply derivation.

 * @derived_key:  Derived key.

 *

 * Return: Zero on success; non-zero otherwise.

 */

static int ext4_derive_key_aes(char deriving_key[EXT4_AES_128_ECB_KEY_SIZE],

			       char source_key[EXT4_AES_256_XTS_KEY_SIZE],

			       char derived_key[EXT4_AES_256_XTS_KEY_SIZE])

{

	int res = 0;

	struct skcipher_request *req = NULL;

	DECLARE_EXT4_COMPLETION_RESULT(ecr);

	struct scatterlist src_sg, dst_sg;

	struct crypto_skcipher *tfm = crypto_alloc_skcipher("ecb(aes)", 0, 0);

	if (IS_ERR(tfm)) {

		res = PTR_ERR(tfm);

		tfm = NULL;

		goto out;

	}

	crypto_skcipher_set_flags(tfm, CRYPTO_TFM_REQ_WEAK_KEY);

	req = skcipher_request_alloc(tfm, GFP_NOFS);

	if (!req) {

		res = -ENOMEM;

		goto out;

	}

	skcipher_request_set_callback(req,

			CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,

			derive_crypt_complete, &ecr);

	res = crypto_skcipher_setkey(tfm, deriving_key,

				     EXT4_AES_128_ECB_KEY_SIZE);

	if (res < 0)

		goto out;

	sg_init_one(&src_sg, source_key, EXT4_AES_256_XTS_KEY_SIZE);

	sg_init_one(&dst_sg, derived_key, EXT4_AES_256_XTS_KEY_SIZE);

	skcipher_request_set_crypt(req, &src_sg, &dst_sg,

				   EXT4_AES_256_XTS_KEY_SIZE, NULL);

	res = crypto_skcipher_encrypt(req);

	if (res == -EINPROGRESS || res == -EBUSY) {

		wait_for_completion(&ecr.completion);

		res = ecr.res;

	}

out:

	skcipher_request_free(req);

	crypto_free_skcipher(tfm);

	return res;

}

void ext4_free_crypt_info(struct ext4_crypt_info *ci)

{

	if (!ci)

		return;

	if (ci->ci_keyring_key)

		key_put(ci->ci_keyring_key);

	crypto_free_skcipher(ci->ci_ctfm);

	kmem_cache_free(ext4_crypt_info_cachep, ci);

}

void ext4_free_encryption_info(struct inode *inode,

			       struct ext4_crypt_info *ci)

{

	struct ext4_inode_info *ei = EXT4_I(inode);

	struct ext4_crypt_info *prev;

	if (ci == NULL)

		ci = ACCESS_ONCE(ei->i_crypt_info);

	if (ci == NULL)

		return;

	prev = cmpxchg(&ei->i_crypt_info, ci, NULL);

	if (prev != ci)

		return;

	ext4_free_crypt_info(ci);

}

int _ext4_get_encryption_info(struct inode *inode)

{

	struct ext4_inode_info *ei = EXT4_I(inode);

	struct ext4_crypt_info *crypt_info;

	char full_key_descriptor[EXT4_KEY_DESC_PREFIX_SIZE +

				 (EXT4_KEY_DESCRIPTOR_SIZE * 2) + 1];

	struct key *keyring_key = NULL;

	struct ext4_encryption_key *master_key;

	struct ext4_encryption_context ctx;

	const struct user_key_payload *ukp;

	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);

	struct crypto_skcipher *ctfm;

	const char *cipher_str;

	char raw_key[EXT4_MAX_KEY_SIZE];

	char mode;

	int res;

	if (!ext4_read_workqueue) {

		res = ext4_init_crypto();

		if (res)

			return res;

	}

retry:

	crypt_info = ACCESS_ONCE(ei->i_crypt_info);

	if (crypt_info) {

		if (!crypt_info->ci_keyring_key ||

		    key_validate(crypt_info->ci_keyring_key) == 0)

			return 0;

		ext4_free_encryption_info(inode, crypt_info);

		goto retry;

	}

	res = ext4_xattr_get(inode, EXT4_XATTR_INDEX_ENCRYPTION,

				 EXT4_XATTR_NAME_ENCRYPTION_CONTEXT,

				 &ctx, sizeof(ctx));

	if (res < 0) {

		if (!DUMMY_ENCRYPTION_ENABLED(sbi))

			return res;

		ctx.contents_encryption_mode = EXT4_ENCRYPTION_MODE_AES_256_XTS;

		ctx.filenames_encryption_mode =

			EXT4_ENCRYPTION_MODE_AES_256_CTS;

		ctx.flags = 0;

	} else if (res != sizeof(ctx))

		return -EINVAL;

	res = 0;

	crypt_info = kmem_cache_alloc(ext4_crypt_info_cachep, GFP_KERNEL);

	if (!crypt_info)

		return -ENOMEM;

	crypt_info->ci_flags = ctx.flags;

	crypt_info->ci_data_mode = ctx.contents_encryption_mode;

	crypt_info->ci_filename_mode = ctx.filenames_encryption_mode;

	crypt_info->ci_ctfm = NULL;