[deliverable/linux.git] / fs / f2fs / crypto.c

/*
 * linux/fs/f2fs/crypto.c
 *
 * Copied from linux/fs/ext4/crypto.c
 *
 * Copyright (C) 2015, Google, Inc.
 * Copyright (C) 2015, Motorola Mobility
 *
 * This contains encryption functions for f2fs
 *
 * Written by Michael Halcrow, 2014.
 *
 * Filename encryption additions
 *	Uday Savagaonkar, 2014
 * Encryption policy handling additions
 *	Ildar Muslukhov, 2014
 * Remove ext4_encrypted_zeroout(),
 *   add f2fs_restore_and_release_control_page()
 *	Jaegeuk Kim, 2015.
 *
 * 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/hash.h>
#include <crypto/sha.h>
#include <keys/user-type.h>
#include <keys/encrypted-type.h>
#include <linux/crypto.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/f2fs_fs.h>
#include <linux/ratelimit.h>
#include <linux/bio.h>

#include "f2fs.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 *f2fs_bounce_page_pool;

static LIST_HEAD(f2fs_free_crypto_ctxs);
static DEFINE_SPINLOCK(f2fs_crypto_ctx_lock);

static struct workqueue_struct *f2fs_read_workqueue;
static DEFINE_MUTEX(crypto_init);

static struct kmem_cache *f2fs_crypto_ctx_cachep;
struct kmem_cache *f2fs_crypt_info_cachep;

/**
 * f2fs_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 f2fs_release_crypto_ctx(struct f2fs_crypto_ctx *ctx)
{
	unsigned long flags;

	if (ctx->flags & F2FS_WRITE_PATH_FL && ctx->w.bounce_page) {
		mempool_free(ctx->w.bounce_page, f2fs_bounce_page_pool);
		ctx->w.bounce_page = NULL;
	}
	ctx->w.control_page = NULL;
	if (ctx->flags & F2FS_CTX_REQUIRES_FREE_ENCRYPT_FL) {
		kmem_cache_free(f2fs_crypto_ctx_cachep, ctx);
	} else {
		spin_lock_irqsave(&f2fs_crypto_ctx_lock, flags);
		list_add(&ctx->free_list, &f2fs_free_crypto_ctxs);
		spin_unlock_irqrestore(&f2fs_crypto_ctx_lock, flags);
	}
}

/**
 * f2fs_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 f2fs_crypto_ctx *f2fs_get_crypto_ctx(struct inode *inode)
{
	struct f2fs_crypto_ctx *ctx = NULL;
	unsigned long flags;
	struct f2fs_crypt_info *ci = F2FS_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(&f2fs_crypto_ctx_lock, flags);
	ctx = list_first_entry_or_null(&f2fs_free_crypto_ctxs,
					struct f2fs_crypto_ctx, free_list);
	if (ctx)
		list_del(&ctx->free_list);
	spin_unlock_irqrestore(&f2fs_crypto_ctx_lock, flags);
	if (!ctx) {
		ctx = kmem_cache_zalloc(f2fs_crypto_ctx_cachep, GFP_NOFS);
		if (!ctx)
			return ERR_PTR(-ENOMEM);
		ctx->flags |= F2FS_CTX_REQUIRES_FREE_ENCRYPT_FL;
	} else {
		ctx->flags &= ~F2FS_CTX_REQUIRES_FREE_ENCRYPT_FL;
	}
	ctx->flags &= ~F2FS_WRITE_PATH_FL;
	return ctx;
}

/*
 * Call f2fs_decrypt on every single page, reusing the encryption
 * context.
 */
static void completion_pages(struct work_struct *work)
{
	struct f2fs_crypto_ctx *ctx =
		container_of(work, struct f2fs_crypto_ctx, r.work);
	struct bio *bio = ctx->r.bio;
	struct bio_vec *bv;
	int i;

	bio_for_each_segment_all(bv, bio, i) {
		struct page *page = bv->bv_page;
		int ret = f2fs_decrypt(ctx, page);

		if (ret) {
			WARN_ON_ONCE(1);
			SetPageError(page);
		} else
			SetPageUptodate(page);
		unlock_page(page);
	}
	f2fs_release_crypto_ctx(ctx);
	bio_put(bio);
}

void f2fs_end_io_crypto_work(struct f2fs_crypto_ctx *ctx, struct bio *bio)
{
	INIT_WORK(&ctx->r.work, completion_pages);
	ctx->r.bio = bio;
	queue_work(f2fs_read_workqueue, &ctx->r.work);
}

static void f2fs_crypto_destroy(void)
{
	struct f2fs_crypto_ctx *pos, *n;

	list_for_each_entry_safe(pos, n, &f2fs_free_crypto_ctxs, free_list)
		kmem_cache_free(f2fs_crypto_ctx_cachep, pos);
	INIT_LIST_HEAD(&f2fs_free_crypto_ctxs);
	if (f2fs_bounce_page_pool)
		mempool_destroy(f2fs_bounce_page_pool);
	f2fs_bounce_page_pool = NULL;
}

/**
 * f2fs_crypto_initialize() - Set up for f2fs 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 f2fs_crypto_initialize(void)
{
	int i, res = -ENOMEM;

	if (f2fs_bounce_page_pool)
		return 0;

	mutex_lock(&crypto_init);
	if (f2fs_bounce_page_pool)
		goto already_initialized;

	for (i = 0; i < num_prealloc_crypto_ctxs; i++) {
		struct f2fs_crypto_ctx *ctx;

		ctx = kmem_cache_zalloc(f2fs_crypto_ctx_cachep, GFP_KERNEL);
		if (!ctx)
			goto fail;
		list_add(&ctx->free_list, &f2fs_free_crypto_ctxs);
	}

	/* must be allocated at the last step to avoid race condition above */
	f2fs_bounce_page_pool =
		mempool_create_page_pool(num_prealloc_crypto_pages, 0);
	if (!f2fs_bounce_page_pool)
		goto fail;

already_initialized:
	mutex_unlock(&crypto_init);
	return 0;
fail:
	f2fs_crypto_destroy();
	mutex_unlock(&crypto_init);
	return res;
}

/**
 * f2fs_exit_crypto() - Shutdown the f2fs encryption system
 */
void f2fs_exit_crypto(void)
{
	f2fs_crypto_destroy();

	if (f2fs_read_workqueue)
		destroy_workqueue(f2fs_read_workqueue);
	if (f2fs_crypto_ctx_cachep)
		kmem_cache_destroy(f2fs_crypto_ctx_cachep);
	if (f2fs_crypt_info_cachep)
		kmem_cache_destroy(f2fs_crypt_info_cachep);
}

int __init f2fs_init_crypto(void)
{
	int res = -ENOMEM;

	f2fs_read_workqueue = alloc_workqueue("f2fs_crypto", WQ_HIGHPRI, 0);
	if (!f2fs_read_workqueue)
		goto fail;

	f2fs_crypto_ctx_cachep = KMEM_CACHE(f2fs_crypto_ctx,
						SLAB_RECLAIM_ACCOUNT);
	if (!f2fs_crypto_ctx_cachep)
		goto fail;

	f2fs_crypt_info_cachep = KMEM_CACHE(f2fs_crypt_info,
						SLAB_RECLAIM_ACCOUNT);
	if (!f2fs_crypt_info_cachep)
		goto fail;

	return 0;
fail:
	f2fs_exit_crypto();
	return res;
}

void f2fs_restore_and_release_control_page(struct page **page)
{
	struct f2fs_crypto_ctx *ctx;
	struct page *bounce_page;

	/* The bounce data pages are unmapped. */
	if ((*page)->mapping)
		return;

	/* The bounce data page is unmapped. */
	bounce_page = *page;
	ctx = (struct f2fs_crypto_ctx *)page_private(bounce_page);

	/* restore control page */
	*page = ctx->w.control_page;

	f2fs_restore_control_page(bounce_page);
}

void f2fs_restore_control_page(struct page *data_page)
{
	struct f2fs_crypto_ctx *ctx =
		(struct f2fs_crypto_ctx *)page_private(data_page);

	set_page_private(data_page, (unsigned long)NULL);
	ClearPagePrivate(data_page);
	unlock_page(data_page);
	f2fs_release_crypto_ctx(ctx);
}

/**
 * f2fs_crypt_complete() - The completion callback for page encryption
 * @req: The asynchronous encryption request context
 * @res: The result of the encryption operation
 */
static void f2fs_crypt_complete(struct crypto_async_request *req, int res)
{
	struct f2fs_completion_result *ecr = req->data;

	if (res == -EINPROGRESS)
		return;
	ecr->res = res;
	complete(&ecr->completion);
}

typedef enum {
	F2FS_DECRYPT = 0,
	F2FS_ENCRYPT,
} f2fs_direction_t;

static int f2fs_page_crypto(struct f2fs_crypto_ctx *ctx,
				struct inode *inode,
				f2fs_direction_t rw,
				pgoff_t index,
				struct page *src_page,
				struct page *dest_page)
{
	u8 xts_tweak[F2FS_XTS_TWEAK_SIZE];
	struct ablkcipher_request *req = NULL;
	DECLARE_F2FS_COMPLETION_RESULT(ecr);
	struct scatterlist dst, src;
	struct f2fs_crypt_info *ci = F2FS_I(inode)->i_crypt_info;
	struct crypto_ablkcipher *tfm = ci->ci_ctfm;
	int res = 0;

	req = ablkcipher_request_alloc(tfm, GFP_NOFS);
	if (!req) {
		printk_ratelimited(KERN_ERR
				"%s: crypto_request_alloc() failed\n",
				__func__);
		return -ENOMEM;
	}
	ablkcipher_request_set_callback(
		req, CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
		f2fs_crypt_complete, &ecr);

	BUILD_BUG_ON(F2FS_XTS_TWEAK_SIZE < sizeof(index));
	memcpy(xts_tweak, &index, sizeof(index));
	memset(&xts_tweak[sizeof(index)], 0,
			F2FS_XTS_TWEAK_SIZE - sizeof(index));

	sg_init_table(&dst, 1);
	sg_set_page(&dst, dest_page, PAGE_CACHE_SIZE, 0);
	sg_init_table(&src, 1);
	sg_set_page(&src, src_page, PAGE_CACHE_SIZE, 0);
	ablkcipher_request_set_crypt(req, &src, &dst, PAGE_CACHE_SIZE,
					xts_tweak);
	if (rw == F2FS_DECRYPT)
		res = crypto_ablkcipher_decrypt(req);
	else
		res = crypto_ablkcipher_encrypt(req);
	if (res == -EINPROGRESS || res == -EBUSY) {
		BUG_ON(req->base.data != &ecr);
		wait_for_completion(&ecr.completion);
		res = ecr.res;
	}
	ablkcipher_request_free(req);
	if (res) {
		printk_ratelimited(KERN_ERR
			"%s: crypto_ablkcipher_encrypt() returned %d\n",
			__func__, res);
		return res;
	}
	return 0;
}

static struct page *alloc_bounce_page(struct f2fs_crypto_ctx *ctx)
{
	ctx->w.bounce_page = mempool_alloc(f2fs_bounce_page_pool, GFP_NOWAIT);
	if (ctx->w.bounce_page == NULL)
		return ERR_PTR(-ENOMEM);
	ctx->flags |= F2FS_WRITE_PATH_FL;
	return ctx->w.bounce_page;
}

/**
 * f2fs_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
 * f2fs_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 *f2fs_encrypt(struct inode *inode,
			  struct page *plaintext_page)
{
	struct f2fs_crypto_ctx *ctx;
	struct page *ciphertext_page = NULL;
	int err;

	BUG_ON(!PageLocked(plaintext_page));

	ctx = f2fs_get_crypto_ctx(inode);
	if (IS_ERR(ctx))
		return (struct page *)ctx;

	/* The encryption operation will require a bounce page. */
	ciphertext_page = alloc_bounce_page(ctx);
	if (IS_ERR(ciphertext_page))
		goto err_out;

	ctx->w.control_page = plaintext_page;
	err = f2fs_page_crypto(ctx, inode, F2FS_ENCRYPT, plaintext_page->index,
					plaintext_page, ciphertext_page);
	if (err) {
		ciphertext_page = ERR_PTR(err);
		goto err_out;
	}

	SetPagePrivate(ciphertext_page);
	set_page_private(ciphertext_page, (unsigned long)ctx);
	lock_page(ciphertext_page);
	return ciphertext_page;

err_out:
	f2fs_release_crypto_ctx(ctx);
	return ciphertext_page;
}

/**
 * f2fs_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 f2fs_decrypt(struct f2fs_crypto_ctx *ctx, struct page *page)
{
	BUG_ON(!PageLocked(page));

	return f2fs_page_crypto(ctx, page->mapping->host,
				F2FS_DECRYPT, page->index, page, page);
}

/*
 * Convenience function which takes care of allocating and
 * deallocating the encryption context
 */
int f2fs_decrypt_one(struct inode *inode, struct page *page)
{
	struct f2fs_crypto_ctx *ctx = f2fs_get_crypto_ctx(inode);
	int ret;

	if (IS_ERR(ctx))
		return PTR_ERR(ctx);
	ret = f2fs_decrypt(ctx, page);
	f2fs_release_crypto_ctx(ctx);
	return ret;
}

bool f2fs_valid_contents_enc_mode(uint32_t mode)
{
	return (mode == F2FS_ENCRYPTION_MODE_AES_256_XTS);
}

/**
 * f2fs_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 f2fs_validate_encryption_key_size(uint32_t mode, uint32_t size)
{
	if (size == f2fs_encryption_key_size(mode))
		return size;
	return 0;
}
Commit	Line	Data
57e5055b JK	1	/*
	2	* linux/fs/f2fs/crypto.c
	3	*
	4	* Copied from linux/fs/ext4/crypto.c
	5	*
	6	* Copyright (C) 2015, Google, Inc.
	7	* Copyright (C) 2015, Motorola Mobility
	8	*
	9	* This contains encryption functions for f2fs
	10	*
	11	* Written by Michael Halcrow, 2014.
	12	*
	13	* Filename encryption additions
	14	* Uday Savagaonkar, 2014
	15	* Encryption policy handling additions
	16	* Ildar Muslukhov, 2014
	17	* Remove ext4_encrypted_zeroout(),
	18	* add f2fs_restore_and_release_control_page()
	19	* Jaegeuk Kim, 2015.
	20	*
	21	* This has not yet undergone a rigorous security audit.
	22	*
	23	* The usage of AES-XTS should conform to recommendations in NIST
	24	* Special Publication 800-38E and IEEE P1619/D16.
	25	*/
	26	#include <crypto/hash.h>
	27	#include <crypto/sha.h>
	28	#include <keys/user-type.h>
	29	#include <keys/encrypted-type.h>
	30	#include <linux/crypto.h>
	31	#include <linux/ecryptfs.h>
	32	#include <linux/gfp.h>
	33	#include <linux/kernel.h>
	34	#include <linux/key.h>
	35	#include <linux/list.h>
	36	#include <linux/mempool.h>
	37	#include <linux/module.h>
	38	#include <linux/mutex.h>
	39	#include <linux/random.h>
	40	#include <linux/scatterlist.h>
	41	#include <linux/spinlock_types.h>
	42	#include <linux/f2fs_fs.h>
	43	#include <linux/ratelimit.h>
	44	#include <linux/bio.h>
	45
	46	#include "f2fs.h"
	47	#include "xattr.h"
	48
	49	/* Encryption added and removed here! (L: */
	50
	51	static unsigned int num_prealloc_crypto_pages = 32;
	52	static unsigned int num_prealloc_crypto_ctxs = 128;
	53
	54	module_param(num_prealloc_crypto_pages, uint, 0444);
	55	MODULE_PARM_DESC(num_prealloc_crypto_pages,
	56	"Number of crypto pages to preallocate");
	57	module_param(num_prealloc_crypto_ctxs, uint, 0444);
	58	MODULE_PARM_DESC(num_prealloc_crypto_ctxs,
	59	"Number of crypto contexts to preallocate");
	60
	61	static mempool_t *f2fs_bounce_page_pool;
	62
	63	static LIST_HEAD(f2fs_free_crypto_ctxs);
	64	static DEFINE_SPINLOCK(f2fs_crypto_ctx_lock);
65
cfc4d971	66	static struct workqueue_struct *f2fs_read_workqueue;
57e5055b JK	67	static DEFINE_MUTEX(crypto_init);
57e5055b JK	68
8bacf6de JK	69	static struct kmem_cache *f2fs_crypto_ctx_cachep;
	70	struct kmem_cache *f2fs_crypt_info_cachep;
	71
57e5055b JK	72	/**
	73	* f2fs_release_crypto_ctx() - Releases an encryption context
	74	* @ctx: The encryption context to release.
	75	*
	76	* If the encryption context was allocated from the pre-allocated pool, returns
	77	* it to that pool. Else, frees it.
	78	*
	79	* If there's a bounce page in the context, this frees that.
	80	*/
	81	void f2fs_release_crypto_ctx(struct f2fs_crypto_ctx *ctx)
	82	{
	83	unsigned long flags;
	84
ca40b030	85	if (ctx->flags & F2FS_WRITE_PATH_FL && ctx->w.bounce_page) {
4683ff83	86	mempool_free(ctx->w.bounce_page, f2fs_bounce_page_pool);
ca40b030	87	ctx->w.bounce_page = NULL;
57e5055b	88	}
ca40b030	89	ctx->w.control_page = NULL;
57e5055b	90	if (ctx->flags & F2FS_CTX_REQUIRES_FREE_ENCRYPT_FL) {
8bacf6de	91	kmem_cache_free(f2fs_crypto_ctx_cachep, ctx);
57e5055b JK	92	} else {
	93	spin_lock_irqsave(&f2fs_crypto_ctx_lock, flags);
	94	list_add(&ctx->free_list, &f2fs_free_crypto_ctxs);
	95	spin_unlock_irqrestore(&f2fs_crypto_ctx_lock, flags);
	96	}
	97	}
	98
57e5055b JK	99	/**
	100	* f2fs_get_crypto_ctx() - Gets an encryption context
	101	* @inode: The inode for which we are doing the crypto
	102	*
	103	* Allocates and initializes an encryption context.
	104	*
	105	* Return: An allocated and initialized encryption context on success; error
	106	* value or NULL otherwise.
	107	*/
	108	struct f2fs_crypto_ctx f2fs_get_crypto_ctx(struct inode inode)
	109	{
	110	struct f2fs_crypto_ctx *ctx = NULL;
57e5055b JK	111	unsigned long flags;
	112	struct f2fs_crypt_info *ci = F2FS_I(inode)->i_crypt_info;
	113
edf3fb8e	114	if (ci == NULL)
7e8e754a	115	return ERR_PTR(-ENOKEY);
edf3fb8e	116
57e5055b JK	117	/*
	118	* We first try getting the ctx from a free list because in
	119	* the common case the ctx will have an allocated and
	120	* initialized crypto tfm, so it's probably a worthwhile
	121	* optimization. For the bounce page, we first try getting it
	122	* from the kernel allocator because that's just about as fast
	123	* as getting it from a list and because a cache of free pages
	124	* should generally be a "last resort" option for a filesystem
	125	* to be able to do its job.
	126	*/
	127	spin_lock_irqsave(&f2fs_crypto_ctx_lock, flags);
	128	ctx = list_first_entry_or_null(&f2fs_free_crypto_ctxs,
	129	struct f2fs_crypto_ctx, free_list);
	130	if (ctx)
	131	list_del(&ctx->free_list);
	132	spin_unlock_irqrestore(&f2fs_crypto_ctx_lock, flags);
	133	if (!ctx) {
8bacf6de	134	ctx = kmem_cache_zalloc(f2fs_crypto_ctx_cachep, GFP_NOFS);
26bf3dc7 JK	135	if (!ctx)
26bf3dc7 JK	136	return ERR_PTR(-ENOMEM);
57e5055b JK	137	ctx->flags \|= F2FS_CTX_REQUIRES_FREE_ENCRYPT_FL;
	138	} else {
	139	ctx->flags &= ~F2FS_CTX_REQUIRES_FREE_ENCRYPT_FL;
	140	}
ca40b030	141	ctx->flags &= ~F2FS_WRITE_PATH_FL;
57e5055b JK	142	return ctx;
	143	}
	144
	145	/*
	146	* Call f2fs_decrypt on every single page, reusing the encryption
	147	* context.
	148	*/
	149	static void completion_pages(struct work_struct *work)
	150	{
	151	struct f2fs_crypto_ctx *ctx =
ca40b030 JK	152	container_of(work, struct f2fs_crypto_ctx, r.work);
ca40b030 JK	153	struct bio *bio = ctx->r.bio;
57e5055b JK	154	struct bio_vec *bv;
	155	int i;
	156
	157	bio_for_each_segment_all(bv, bio, i) {
	158	struct page *page = bv->bv_page;
	159	int ret = f2fs_decrypt(ctx, page);
	160
	161	if (ret) {
	162	WARN_ON_ONCE(1);
	163	SetPageError(page);
	164	} else
	165	SetPageUptodate(page);
	166	unlock_page(page);
	167	}
	168	f2fs_release_crypto_ctx(ctx);
	169	bio_put(bio);
	170	}
	171
	172	void f2fs_end_io_crypto_work(struct f2fs_crypto_ctx ctx, struct bio bio)
	173	{
ca40b030 JK	174	INIT_WORK(&ctx->r.work, completion_pages);
	175	ctx->r.bio = bio;
	176	queue_work(f2fs_read_workqueue, &ctx->r.work);
57e5055b JK	177	}
57e5055b JK	178
cfc4d971	179	static void f2fs_crypto_destroy(void)
57e5055b JK	180	{
	181	struct f2fs_crypto_ctx pos, n;
	182
26bf3dc7	183	list_for_each_entry_safe(pos, n, &f2fs_free_crypto_ctxs, free_list)
8bacf6de	184	kmem_cache_free(f2fs_crypto_ctx_cachep, pos);
57e5055b JK	185	INIT_LIST_HEAD(&f2fs_free_crypto_ctxs);
	186	if (f2fs_bounce_page_pool)
	187	mempool_destroy(f2fs_bounce_page_pool);
	188	f2fs_bounce_page_pool = NULL;
57e5055b JK	189	}
	190
	191	/**
cfc4d971	192	* f2fs_crypto_initialize() - Set up for f2fs encryption.
57e5055b JK	193	*
	194	* We only call this when we start accessing encrypted files, since it
	195	* results in memory getting allocated that wouldn't otherwise be used.
	196	*
	197	* Return: Zero on success, non-zero otherwise.
	198	*/
cfc4d971	199	int f2fs_crypto_initialize(void)
57e5055b	200	{
8bacf6de	201	int i, res = -ENOMEM;
57e5055b	202
cfc4d971 JK	203	if (f2fs_bounce_page_pool)
	204	return 0;
	205
57e5055b	206	mutex_lock(&crypto_init);
cfc4d971	207	if (f2fs_bounce_page_pool)
57e5055b JK	208	goto already_initialized;
57e5055b JK	209
57e5055b JK	210	for (i = 0; i < num_prealloc_crypto_ctxs; i++) {
	211	struct f2fs_crypto_ctx *ctx;
	212
8bacf6de	213	ctx = kmem_cache_zalloc(f2fs_crypto_ctx_cachep, GFP_KERNEL);
cfc4d971	214	if (!ctx)
57e5055b	215	goto fail;
57e5055b JK	216	list_add(&ctx->free_list, &f2fs_free_crypto_ctxs);
	217	}
	218
cfc4d971	219	/* must be allocated at the last step to avoid race condition above */
57e5055b JK	220	f2fs_bounce_page_pool =
57e5055b JK	221	mempool_create_page_pool(num_prealloc_crypto_pages, 0);
cfc4d971	222	if (!f2fs_bounce_page_pool)
57e5055b	223	goto fail;
cfc4d971	224
57e5055b JK	225	already_initialized:
	226	mutex_unlock(&crypto_init);
	227	return 0;
	228	fail:
cfc4d971	229	f2fs_crypto_destroy();
57e5055b JK	230	mutex_unlock(&crypto_init);
	231	return res;
	232	}
	233
cfc4d971 JK	234	/**
	235	* f2fs_exit_crypto() - Shutdown the f2fs encryption system
	236	*/
	237	void f2fs_exit_crypto(void)
	238	{
	239	f2fs_crypto_destroy();
	240
	241	if (f2fs_read_workqueue)
	242	destroy_workqueue(f2fs_read_workqueue);
	243	if (f2fs_crypto_ctx_cachep)
	244	kmem_cache_destroy(f2fs_crypto_ctx_cachep);
	245	if (f2fs_crypt_info_cachep)
	246	kmem_cache_destroy(f2fs_crypt_info_cachep);
	247	}
	248
	249	int __init f2fs_init_crypto(void)
	250	{
	251	int res = -ENOMEM;
	252
	253	f2fs_read_workqueue = alloc_workqueue("f2fs_crypto", WQ_HIGHPRI, 0);
	254	if (!f2fs_read_workqueue)
	255	goto fail;
	256
	257	f2fs_crypto_ctx_cachep = KMEM_CACHE(f2fs_crypto_ctx,
	258	SLAB_RECLAIM_ACCOUNT);
	259	if (!f2fs_crypto_ctx_cachep)
	260	goto fail;
	261
	262	f2fs_crypt_info_cachep = KMEM_CACHE(f2fs_crypt_info,
	263	SLAB_RECLAIM_ACCOUNT);
	264	if (!f2fs_crypt_info_cachep)
	265	goto fail;
	266
	267	return 0;
	268	fail:
	269	f2fs_exit_crypto();
	270	return res;
	271	}
	272
57e5055b JK	273	void f2fs_restore_and_release_control_page(struct page **page)
	274	{
	275	struct f2fs_crypto_ctx *ctx;
	276	struct page *bounce_page;
	277
	278	/* The bounce data pages are unmapped. */
	279	if ((*page)->mapping)
	280	return;
	281
	282	/* The bounce data page is unmapped. */
	283	bounce_page = *page;
	284	ctx = (struct f2fs_crypto_ctx *)page_private(bounce_page);
	285
	286	/* restore control page */
ca40b030	287	*page = ctx->w.control_page;
57e5055b JK	288
	289	f2fs_restore_control_page(bounce_page);
	290	}
	291
	292	void f2fs_restore_control_page(struct page *data_page)
	293	{
	294	struct f2fs_crypto_ctx *ctx =
	295	(struct f2fs_crypto_ctx *)page_private(data_page);
	296
	297	set_page_private(data_page, (unsigned long)NULL);
	298	ClearPagePrivate(data_page);
	299	unlock_page(data_page);
	300	f2fs_release_crypto_ctx(ctx);
	301	}
	302
	303	/**
	304	* f2fs_crypt_complete() - The completion callback for page encryption
	305	* @req: The asynchronous encryption request context
	306	* @res: The result of the encryption operation
	307	*/
	308	static void f2fs_crypt_complete(struct crypto_async_request *req, int res)
	309	{
	310	struct f2fs_completion_result *ecr = req->data;
	311
	312	if (res == -EINPROGRESS)
	313	return;
	314	ecr->res = res;
	315	complete(&ecr->completion);
	316	}
	317
	318	typedef enum {
	319	F2FS_DECRYPT = 0,
	320	F2FS_ENCRYPT,
	321	} f2fs_direction_t;
	322
	323	static int f2fs_page_crypto(struct f2fs_crypto_ctx *ctx,
	324	struct inode *inode,
	325	f2fs_direction_t rw,
	326	pgoff_t index,
	327	struct page *src_page,
	328	struct page *dest_page)
	329	{
	330	u8 xts_tweak[F2FS_XTS_TWEAK_SIZE];
	331	struct ablkcipher_request *req = NULL;
	332	DECLARE_F2FS_COMPLETION_RESULT(ecr);
	333	struct scatterlist dst, src;
26bf3dc7 JK	334	struct f2fs_crypt_info *ci = F2FS_I(inode)->i_crypt_info;
26bf3dc7 JK	335	struct crypto_ablkcipher *tfm = ci->ci_ctfm;
57e5055b JK	336	int res = 0;
57e5055b JK	337
26bf3dc7	338	req = ablkcipher_request_alloc(tfm, GFP_NOFS);
57e5055b JK	339	if (!req) {
	340	printk_ratelimited(KERN_ERR
	341	"%s: crypto_request_alloc() failed\n",
	342	__func__);
	343	return -ENOMEM;
	344	}
	345	ablkcipher_request_set_callback(
	346	req, CRYPTO_TFM_REQ_MAY_BACKLOG \| CRYPTO_TFM_REQ_MAY_SLEEP,
	347	f2fs_crypt_complete, &ecr);
	348
	349	BUILD_BUG_ON(F2FS_XTS_TWEAK_SIZE < sizeof(index));
	350	memcpy(xts_tweak, &index, sizeof(index));
	351	memset(&xts_tweak[sizeof(index)], 0,
	352	F2FS_XTS_TWEAK_SIZE - sizeof(index));
	353
	354	sg_init_table(&dst, 1);
	355	sg_set_page(&dst, dest_page, PAGE_CACHE_SIZE, 0);
	356	sg_init_table(&src, 1);
	357	sg_set_page(&src, src_page, PAGE_CACHE_SIZE, 0);
	358	ablkcipher_request_set_crypt(req, &src, &dst, PAGE_CACHE_SIZE,
	359	xts_tweak);
	360	if (rw == F2FS_DECRYPT)
	361	res = crypto_ablkcipher_decrypt(req);
	362	else
	363	res = crypto_ablkcipher_encrypt(req);
	364	if (res == -EINPROGRESS \|\| res == -EBUSY) {
	365	BUG_ON(req->base.data != &ecr);
	366	wait_for_completion(&ecr.completion);
	367	res = ecr.res;
	368	}
	369	ablkcipher_request_free(req);
	370	if (res) {
	371	printk_ratelimited(KERN_ERR
	372	"%s: crypto_ablkcipher_encrypt() returned %d\n",
	373	__func__, res);
	374	return res;
	375	}
	376	return 0;
	377	}
	378
43f54cd5 JK	379	static struct page alloc_bounce_page(struct f2fs_crypto_ctx ctx)
	380	{
	381	ctx->w.bounce_page = mempool_alloc(f2fs_bounce_page_pool, GFP_NOWAIT);
	382	if (ctx->w.bounce_page == NULL)
	383	return ERR_PTR(-ENOMEM);
	384	ctx->flags \|= F2FS_WRITE_PATH_FL;
	385	return ctx->w.bounce_page;
	386	}
	387
57e5055b JK	388	/**
	389	* f2fs_encrypt() - Encrypts a page
	390	* @inode: The inode for which the encryption should take place
	391	* @plaintext_page: The page to encrypt. Must be locked.
	392	*
	393	* Allocates a ciphertext page and encrypts plaintext_page into it using the ctx
	394	* encryption context.
	395	*
	396	* Called on the page write path. The caller must call
	397	* f2fs_restore_control_page() on the returned ciphertext page to
	398	* release the bounce buffer and the encryption context.
	399	*
	400	* Return: An allocated page with the encrypted content on success. Else, an
	401	* error value or NULL.
	402	*/
	403	struct page f2fs_encrypt(struct inode inode,
	404	struct page *plaintext_page)
	405	{
	406	struct f2fs_crypto_ctx *ctx;
	407	struct page *ciphertext_page = NULL;
	408	int err;
	409
	410	BUG_ON(!PageLocked(plaintext_page));
	411
	412	ctx = f2fs_get_crypto_ctx(inode);
	413	if (IS_ERR(ctx))
	414	return (struct page *)ctx;
	415
	416	/* The encryption operation will require a bounce page. */
43f54cd5 JK	417	ciphertext_page = alloc_bounce_page(ctx);
43f54cd5 JK	418	if (IS_ERR(ciphertext_page))
4683ff83	419	goto err_out;
4683ff83	420
ca40b030	421	ctx->w.control_page = plaintext_page;
57e5055b JK	422	err = f2fs_page_crypto(ctx, inode, F2FS_ENCRYPT, plaintext_page->index,
57e5055b JK	423	plaintext_page, ciphertext_page);
43f54cd5 JK	424	if (err) {
43f54cd5 JK	425	ciphertext_page = ERR_PTR(err);
4683ff83	426	goto err_out;
43f54cd5	427	}
4683ff83	428
57e5055b JK	429	SetPagePrivate(ciphertext_page);
	430	set_page_private(ciphertext_page, (unsigned long)ctx);
	431	lock_page(ciphertext_page);
	432	return ciphertext_page;
4683ff83 JK	433
	434	err_out:
	435	f2fs_release_crypto_ctx(ctx);
43f54cd5	436	return ciphertext_page;
57e5055b JK	437	}
	438
	439	/**
	440	* f2fs_decrypt() - Decrypts a page in-place
	441	* @ctx: The encryption context.
	442	* @page: The page to decrypt. Must be locked.
	443	*
	444	* Decrypts page in-place using the ctx encryption context.
	445	*
	446	* Called from the read completion callback.
	447	*
	448	* Return: Zero on success, non-zero otherwise.
	449	*/
	450	int f2fs_decrypt(struct f2fs_crypto_ctx ctx, struct page page)
	451	{
	452	BUG_ON(!PageLocked(page));
	453
	454	return f2fs_page_crypto(ctx, page->mapping->host,
	455	F2FS_DECRYPT, page->index, page, page);
	456	}
	457
	458	/*
	459	* Convenience function which takes care of allocating and
	460	* deallocating the encryption context
	461	*/
	462	int f2fs_decrypt_one(struct inode inode, struct page page)
	463	{
	464	struct f2fs_crypto_ctx *ctx = f2fs_get_crypto_ctx(inode);
	465	int ret;
	466
7e8e754a JK	467	if (IS_ERR(ctx))
7e8e754a JK	468	return PTR_ERR(ctx);
57e5055b JK	469	ret = f2fs_decrypt(ctx, page);
	470	f2fs_release_crypto_ctx(ctx);
	471	return ret;
	472	}
	473
	474	bool f2fs_valid_contents_enc_mode(uint32_t mode)
	475	{
	476	return (mode == F2FS_ENCRYPTION_MODE_AES_256_XTS);
	477	}
	478
	479	/**
	480	* f2fs_validate_encryption_key_size() - Validate the encryption key size
	481	* @mode: The key mode.
	482	* @size: The key size to validate.
	483	*
	484	* Return: The validated key size for @mode. Zero if invalid.
	485	*/
	486	uint32_t f2fs_validate_encryption_key_size(uint32_t mode, uint32_t size)
	487	{
	488	if (size == f2fs_encryption_key_size(mode))
	489	return size;
	490	return 0;
	491	}