[linux.git] / fs / ext4 / crypto.c

/*
 * 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,
};
Commit	Line	Data
b30ab0e0 MH	1	/*
	2	* linux/fs/ext4/crypto.c
	3	*
	4	* Copyright (C) 2015, Google, Inc.
	5	*
	6	* This contains encryption functions for ext4
	7	*
	8	* Written by Michael Halcrow, 2014.
	9	*
	10	* Filename encryption additions
	11	* Uday Savagaonkar, 2014
	12	* Encryption policy handling additions
	13	* Ildar Muslukhov, 2014
	14	*
	15	* This has not yet undergone a rigorous security audit.
	16	*
	17	* The usage of AES-XTS should conform to recommendations in NIST
	18	* Special Publication 800-38E and IEEE P1619/D16.
	19	*/
	20
3f32a5be	21	#include <crypto/skcipher.h>
b30ab0e0 MH	22	#include <keys/user-type.h>
b30ab0e0 MH	23	#include <keys/encrypted-type.h>
b30ab0e0 MH	24	#include <linux/ecryptfs.h>
	25	#include <linux/gfp.h>
	26	#include <linux/kernel.h>
	27	#include <linux/key.h>
	28	#include <linux/list.h>
	29	#include <linux/mempool.h>
	30	#include <linux/module.h>
	31	#include <linux/mutex.h>
	32	#include <linux/random.h>
	33	#include <linux/scatterlist.h>
	34	#include <linux/spinlock_types.h>
03a8bb0e	35	#include <linux/namei.h>
b30ab0e0 MH	36
	37	#include "ext4_extents.h"
	38	#include "xattr.h"
	39
	40	/* Encryption added and removed here! (L: */
	41
	42	static unsigned int num_prealloc_crypto_pages = 32;
	43	static unsigned int num_prealloc_crypto_ctxs = 128;
	44
	45	module_param(num_prealloc_crypto_pages, uint, 0444);
	46	MODULE_PARM_DESC(num_prealloc_crypto_pages,
	47	"Number of crypto pages to preallocate");
	48	module_param(num_prealloc_crypto_ctxs, uint, 0444);
	49	MODULE_PARM_DESC(num_prealloc_crypto_ctxs,
	50	"Number of crypto contexts to preallocate");
	51
	52	static mempool_t *ext4_bounce_page_pool;
	53
	54	static LIST_HEAD(ext4_free_crypto_ctxs);
	55	static DEFINE_SPINLOCK(ext4_crypto_ctx_lock);
	56
8ee03714 TT	57	static struct kmem_cache *ext4_crypto_ctx_cachep;
	58	struct kmem_cache *ext4_crypt_info_cachep;
	59
b30ab0e0 MH	60	/**
	61	* ext4_release_crypto_ctx() - Releases an encryption context
	62	* @ctx: The encryption context to release.
	63	*
	64	* If the encryption context was allocated from the pre-allocated pool, returns
	65	* it to that pool. Else, frees it.
	66	*
	67	* If there's a bounce page in the context, this frees that.
	68	*/
	69	void ext4_release_crypto_ctx(struct ext4_crypto_ctx *ctx)
	70	{
	71	unsigned long flags;
	72
3dbb5eb9 TT	73	if (ctx->flags & EXT4_WRITE_PATH_FL && ctx->w.bounce_page)
3dbb5eb9 TT	74	mempool_free(ctx->w.bounce_page, ext4_bounce_page_pool);
614def70 TT	75	ctx->w.bounce_page = NULL;
614def70 TT	76	ctx->w.control_page = NULL;
b30ab0e0	77	if (ctx->flags & EXT4_CTX_REQUIRES_FREE_ENCRYPT_FL) {
8ee03714	78	kmem_cache_free(ext4_crypto_ctx_cachep, ctx);
b30ab0e0 MH	79	} else {
	80	spin_lock_irqsave(&ext4_crypto_ctx_lock, flags);
	81	list_add(&ctx->free_list, &ext4_free_crypto_ctxs);
	82	spin_unlock_irqrestore(&ext4_crypto_ctx_lock, flags);
	83	}
	84	}
	85
b30ab0e0 MH	86	/**
	87	* ext4_get_crypto_ctx() - Gets an encryption context
	88	* @inode: The inode for which we are doing the crypto
	89	*
	90	* Allocates and initializes an encryption context.
	91	*
	92	* Return: An allocated and initialized encryption context on success; error
	93	* value or NULL otherwise.
	94	*/
c9af28fd TT	95	struct ext4_crypto_ctx ext4_get_crypto_ctx(struct inode inode,
c9af28fd TT	96	gfp_t gfp_flags)
b30ab0e0 MH	97	{
	98	struct ext4_crypto_ctx *ctx = NULL;
	99	int res = 0;
	100	unsigned long flags;
b7236e21	101	struct ext4_crypt_info *ci = EXT4_I(inode)->i_crypt_info;
b30ab0e0	102
abdd438b TT	103	if (ci == NULL)
abdd438b TT	104	return ERR_PTR(-ENOKEY);
b30ab0e0 MH	105
	106	/*
	107	* We first try getting the ctx from a free list because in
	108	* the common case the ctx will have an allocated and
	109	* initialized crypto tfm, so it's probably a worthwhile
	110	* optimization. For the bounce page, we first try getting it
	111	* from the kernel allocator because that's just about as fast
	112	* as getting it from a list and because a cache of free pages
	113	* should generally be a "last resort" option for a filesystem
	114	* to be able to do its job.
	115	*/
	116	spin_lock_irqsave(&ext4_crypto_ctx_lock, flags);
	117	ctx = list_first_entry_or_null(&ext4_free_crypto_ctxs,
	118	struct ext4_crypto_ctx, free_list);
	119	if (ctx)
	120	list_del(&ctx->free_list);
	121	spin_unlock_irqrestore(&ext4_crypto_ctx_lock, flags);
	122	if (!ctx) {
c9af28fd	123	ctx = kmem_cache_zalloc(ext4_crypto_ctx_cachep, gfp_flags);
8ee03714 TT	124	if (!ctx) {
8ee03714 TT	125	res = -ENOMEM;
b30ab0e0 MH	126	goto out;
	127	}
	128	ctx->flags \|= EXT4_CTX_REQUIRES_FREE_ENCRYPT_FL;
	129	} else {
	130	ctx->flags &= ~EXT4_CTX_REQUIRES_FREE_ENCRYPT_FL;
	131	}
614def70	132	ctx->flags &= ~EXT4_WRITE_PATH_FL;
b30ab0e0	133
b30ab0e0 MH	134	out:
	135	if (res) {
	136	if (!IS_ERR_OR_NULL(ctx))
	137	ext4_release_crypto_ctx(ctx);
	138	ctx = ERR_PTR(res);
	139	}
	140	return ctx;
	141	}
	142
	143	struct workqueue_struct *ext4_read_workqueue;
	144	static DEFINE_MUTEX(crypto_init);
	145
	146	/**
	147	* ext4_exit_crypto() - Shutdown the ext4 encryption system
	148	*/
	149	void ext4_exit_crypto(void)
	150	{
	151	struct ext4_crypto_ctx pos, n;
	152
c936e1ec	153	list_for_each_entry_safe(pos, n, &ext4_free_crypto_ctxs, free_list)
8ee03714	154	kmem_cache_free(ext4_crypto_ctx_cachep, pos);
b30ab0e0 MH	155	INIT_LIST_HEAD(&ext4_free_crypto_ctxs);
	156	if (ext4_bounce_page_pool)
	157	mempool_destroy(ext4_bounce_page_pool);
	158	ext4_bounce_page_pool = NULL;
	159	if (ext4_read_workqueue)
	160	destroy_workqueue(ext4_read_workqueue);
	161	ext4_read_workqueue = NULL;
8ee03714 TT	162	if (ext4_crypto_ctx_cachep)
	163	kmem_cache_destroy(ext4_crypto_ctx_cachep);
	164	ext4_crypto_ctx_cachep = NULL;
	165	if (ext4_crypt_info_cachep)
	166	kmem_cache_destroy(ext4_crypt_info_cachep);
	167	ext4_crypt_info_cachep = NULL;
b30ab0e0 MH	168	}
	169
	170	/**
	171	* ext4_init_crypto() - Set up for ext4 encryption.
	172	*
	173	* We only call this when we start accessing encrypted files, since it
	174	* results in memory getting allocated that wouldn't otherwise be used.
	175	*
	176	* Return: Zero on success, non-zero otherwise.
	177	*/
	178	int ext4_init_crypto(void)
	179	{
8ee03714	180	int i, res = -ENOMEM;
b30ab0e0 MH	181
	182	mutex_lock(&crypto_init);
	183	if (ext4_read_workqueue)
	184	goto already_initialized;
	185	ext4_read_workqueue = alloc_workqueue("ext4_crypto", WQ_HIGHPRI, 0);
8ee03714 TT	186	if (!ext4_read_workqueue)
	187	goto fail;
	188
	189	ext4_crypto_ctx_cachep = KMEM_CACHE(ext4_crypto_ctx,
	190	SLAB_RECLAIM_ACCOUNT);
	191	if (!ext4_crypto_ctx_cachep)
	192	goto fail;
	193
	194	ext4_crypt_info_cachep = KMEM_CACHE(ext4_crypt_info,
	195	SLAB_RECLAIM_ACCOUNT);
	196	if (!ext4_crypt_info_cachep)
b30ab0e0	197	goto fail;
b30ab0e0 MH	198
	199	for (i = 0; i < num_prealloc_crypto_ctxs; i++) {
	200	struct ext4_crypto_ctx *ctx;
	201
8ee03714 TT	202	ctx = kmem_cache_zalloc(ext4_crypto_ctx_cachep, GFP_NOFS);
	203	if (!ctx) {
	204	res = -ENOMEM;
b30ab0e0 MH	205	goto fail;
	206	}
	207	list_add(&ctx->free_list, &ext4_free_crypto_ctxs);
	208	}
	209
	210	ext4_bounce_page_pool =
	211	mempool_create_page_pool(num_prealloc_crypto_pages, 0);
	212	if (!ext4_bounce_page_pool) {
	213	res = -ENOMEM;
	214	goto fail;
	215	}
	216	already_initialized:
	217	mutex_unlock(&crypto_init);
	218	return 0;
	219	fail:
	220	ext4_exit_crypto();
	221	mutex_unlock(&crypto_init);
	222	return res;
	223	}
	224
	225	void ext4_restore_control_page(struct page *data_page)
	226	{
	227	struct ext4_crypto_ctx *ctx =
	228	(struct ext4_crypto_ctx *)page_private(data_page);
	229
	230	set_page_private(data_page, (unsigned long)NULL);
	231	ClearPagePrivate(data_page);
	232	unlock_page(data_page);
	233	ext4_release_crypto_ctx(ctx);
	234	}
	235
	236	/**
	237	* ext4_crypt_complete() - The completion callback for page encryption
	238	* @req: The asynchronous encryption request context
	239	* @res: The result of the encryption operation
	240	*/
	241	static void ext4_crypt_complete(struct crypto_async_request *req, int res)
	242	{
	243	struct ext4_completion_result *ecr = req->data;
	244
	245	if (res == -EINPROGRESS)
	246	return;
	247	ecr->res = res;
	248	complete(&ecr->completion);
	249	}
	250
	251	typedef enum {
	252	EXT4_DECRYPT = 0,
	253	EXT4_ENCRYPT,
	254	} ext4_direction_t;
	255
3684de8c	256	static int ext4_page_crypto(struct inode *inode,
b30ab0e0 MH	257	ext4_direction_t rw,
	258	pgoff_t index,
	259	struct page *src_page,
c9af28fd TT	260	struct page *dest_page,
c9af28fd TT	261	gfp_t gfp_flags)
b30ab0e0 MH	262
	263	{
	264	u8 xts_tweak[EXT4_XTS_TWEAK_SIZE];
3f32a5be	265	struct skcipher_request *req = NULL;
b30ab0e0 MH	266	DECLARE_EXT4_COMPLETION_RESULT(ecr);
b30ab0e0 MH	267	struct scatterlist dst, src;
c936e1ec	268	struct ext4_crypt_info *ci = EXT4_I(inode)->i_crypt_info;
3f32a5be	269	struct crypto_skcipher *tfm = ci->ci_ctfm;
b30ab0e0 MH	270	int res = 0;
b30ab0e0 MH	271
c9af28fd	272	req = skcipher_request_alloc(tfm, gfp_flags);
b30ab0e0 MH	273	if (!req) {
	274	printk_ratelimited(KERN_ERR
	275	"%s: crypto_request_alloc() failed\n",
	276	__func__);
	277	return -ENOMEM;
	278	}
3f32a5be	279	skcipher_request_set_callback(
b30ab0e0 MH	280	req, CRYPTO_TFM_REQ_MAY_BACKLOG \| CRYPTO_TFM_REQ_MAY_SLEEP,
	281	ext4_crypt_complete, &ecr);
	282
	283	BUILD_BUG_ON(EXT4_XTS_TWEAK_SIZE < sizeof(index));
	284	memcpy(xts_tweak, &index, sizeof(index));
	285	memset(&xts_tweak[sizeof(index)], 0,
	286	EXT4_XTS_TWEAK_SIZE - sizeof(index));
	287
	288	sg_init_table(&dst, 1);
09cbfeaf	289	sg_set_page(&dst, dest_page, PAGE_SIZE, 0);
b30ab0e0	290	sg_init_table(&src, 1);
09cbfeaf KS	291	sg_set_page(&src, src_page, PAGE_SIZE, 0);
09cbfeaf KS	292	skcipher_request_set_crypt(req, &src, &dst, PAGE_SIZE,
3f32a5be	293	xts_tweak);
b30ab0e0	294	if (rw == EXT4_DECRYPT)
3f32a5be	295	res = crypto_skcipher_decrypt(req);
b30ab0e0	296	else
3f32a5be	297	res = crypto_skcipher_encrypt(req);
b30ab0e0	298	if (res == -EINPROGRESS \|\| res == -EBUSY) {
b30ab0e0 MH	299	wait_for_completion(&ecr.completion);
	300	res = ecr.res;
	301	}
3f32a5be	302	skcipher_request_free(req);
b30ab0e0 MH	303	if (res) {
	304	printk_ratelimited(
	305	KERN_ERR
3f32a5be	306	"%s: crypto_skcipher_encrypt() returned %d\n",
b30ab0e0 MH	307	__func__, res);
	308	return res;
	309	}
	310	return 0;
	311	}
	312
c9af28fd TT	313	static struct page alloc_bounce_page(struct ext4_crypto_ctx ctx,
c9af28fd TT	314	gfp_t gfp_flags)
95ea68b4	315	{
c9af28fd	316	ctx->w.bounce_page = mempool_alloc(ext4_bounce_page_pool, gfp_flags);
3dbb5eb9 TT	317	if (ctx->w.bounce_page == NULL)
3dbb5eb9 TT	318	return ERR_PTR(-ENOMEM);
95ea68b4	319	ctx->flags \|= EXT4_WRITE_PATH_FL;
3dbb5eb9	320	return ctx->w.bounce_page;
95ea68b4 TT	321	}
95ea68b4 TT	322
b30ab0e0 MH	323	/**
	324	* ext4_encrypt() - Encrypts a page
	325	* @inode: The inode for which the encryption should take place
	326	* @plaintext_page: The page to encrypt. Must be locked.
	327	*
	328	* Allocates a ciphertext page and encrypts plaintext_page into it using the ctx
	329	* encryption context.
	330	*
	331	* Called on the page write path. The caller must call
	332	* ext4_restore_control_page() on the returned ciphertext page to
	333	* release the bounce buffer and the encryption context.
	334	*
	335	* Return: An allocated page with the encrypted content on success. Else, an
	336	* error value or NULL.
	337	*/
	338	struct page ext4_encrypt(struct inode inode,
c9af28fd TT	339	struct page *plaintext_page,
c9af28fd TT	340	gfp_t gfp_flags)
b30ab0e0 MH	341	{
	342	struct ext4_crypto_ctx *ctx;
	343	struct page *ciphertext_page = NULL;
	344	int err;
	345
	346	BUG_ON(!PageLocked(plaintext_page));
	347
c9af28fd	348	ctx = ext4_get_crypto_ctx(inode, gfp_flags);
b30ab0e0 MH	349	if (IS_ERR(ctx))
	350	return (struct page *) ctx;
	351
	352	/* The encryption operation will require a bounce page. */
c9af28fd	353	ciphertext_page = alloc_bounce_page(ctx, gfp_flags);
95ea68b4 TT	354	if (IS_ERR(ciphertext_page))
95ea68b4 TT	355	goto errout;
614def70	356	ctx->w.control_page = plaintext_page;
3684de8c	357	err = ext4_page_crypto(inode, EXT4_ENCRYPT, plaintext_page->index,
c9af28fd	358	plaintext_page, ciphertext_page, gfp_flags);
b30ab0e0	359	if (err) {
95ea68b4 TT	360	ciphertext_page = ERR_PTR(err);
95ea68b4 TT	361	errout:
b30ab0e0	362	ext4_release_crypto_ctx(ctx);
95ea68b4	363	return ciphertext_page;
b30ab0e0 MH	364	}
	365	SetPagePrivate(ciphertext_page);
	366	set_page_private(ciphertext_page, (unsigned long)ctx);
	367	lock_page(ciphertext_page);
	368	return ciphertext_page;
	369	}
	370
	371	/**
	372	* ext4_decrypt() - Decrypts a page in-place
	373	* @ctx: The encryption context.
	374	* @page: The page to decrypt. Must be locked.
	375	*
	376	* Decrypts page in-place using the ctx encryption context.
	377	*
	378	* Called from the read completion callback.
	379	*
	380	* Return: Zero on success, non-zero otherwise.
	381	*/
3684de8c	382	int ext4_decrypt(struct page *page)
b30ab0e0 MH	383	{
	384	BUG_ON(!PageLocked(page));
	385
c9af28fd TT	386	return ext4_page_crypto(page->mapping->host, EXT4_DECRYPT,
c9af28fd TT	387	page->index, page, page, GFP_NOFS);
b30ab0e0 MH	388	}
b30ab0e0 MH	389
53085fac JK	390	int ext4_encrypted_zeroout(struct inode *inode, ext4_lblk_t lblk,
53085fac JK	391	ext4_fsblk_t pblk, ext4_lblk_t len)
b30ab0e0 MH	392	{
	393	struct ext4_crypto_ctx *ctx;
	394	struct page *ciphertext_page = NULL;
	395	struct bio *bio;
36086d43 TT	396	int ret, err = 0;
	397
	398	#if 0
	399	ext4_msg(inode->i_sb, KERN_CRIT,
	400	"ext4_encrypted_zeroout ino %lu lblk %u len %u",
	401	(unsigned long) inode->i_ino, lblk, len);
	402	#endif
b30ab0e0	403
09cbfeaf	404	BUG_ON(inode->i_sb->s_blocksize != PAGE_SIZE);
b30ab0e0	405
c9af28fd	406	ctx = ext4_get_crypto_ctx(inode, GFP_NOFS);
b30ab0e0 MH	407	if (IS_ERR(ctx))
	408	return PTR_ERR(ctx);
	409
c9af28fd	410	ciphertext_page = alloc_bounce_page(ctx, GFP_NOWAIT);
95ea68b4 TT	411	if (IS_ERR(ciphertext_page)) {
	412	err = PTR_ERR(ciphertext_page);
	413	goto errout;
b30ab0e0	414	}
b30ab0e0 MH	415
b30ab0e0 MH	416	while (len--) {
3684de8c	417	err = ext4_page_crypto(inode, EXT4_ENCRYPT, lblk,
c9af28fd TT	418	ZERO_PAGE(0), ciphertext_page,
c9af28fd TT	419	GFP_NOFS);
b30ab0e0 MH	420	if (err)
	421	goto errout;
	422
c9af28fd	423	bio = bio_alloc(GFP_NOWAIT, 1);
b30ab0e0 MH	424	if (!bio) {
	425	err = -ENOMEM;
	426	goto errout;
	427	}
	428	bio->bi_bdev = inode->i_sb->s_bdev;
36086d43 TT	429	bio->bi_iter.bi_sector =
	430	pblk << (inode->i_sb->s_blocksize_bits - 9);
	431	ret = bio_add_page(bio, ciphertext_page,
b30ab0e0	432	inode->i_sb->s_blocksize, 0);
36086d43 TT	433	if (ret != inode->i_sb->s_blocksize) {
	434	/* should never happen! */
	435	ext4_msg(inode->i_sb, KERN_ERR,
	436	"bio_add_page failed: %d", ret);
	437	WARN_ON(1);
b30ab0e0	438	bio_put(bio);
36086d43	439	err = -EIO;
b30ab0e0 MH	440	goto errout;
	441	}
	442	err = submit_bio_wait(WRITE, bio);
36086d43 TT	443	if ((err == 0) && bio->bi_error)
36086d43 TT	444	err = -EIO;
95ea68b4	445	bio_put(bio);
b30ab0e0 MH	446	if (err)
b30ab0e0 MH	447	goto errout;
36086d43	448	lblk++; pblk++;
b30ab0e0 MH	449	}
	450	err = 0;
	451	errout:
	452	ext4_release_crypto_ctx(ctx);
	453	return err;
	454	}
	455
	456	bool ext4_valid_contents_enc_mode(uint32_t mode)
	457	{
	458	return (mode == EXT4_ENCRYPTION_MODE_AES_256_XTS);
	459	}
	460
	461	/**
	462	* ext4_validate_encryption_key_size() - Validate the encryption key size
	463	* @mode: The key mode.
	464	* @size: The key size to validate.
	465	*
	466	* Return: The validated key size for @mode. Zero if invalid.
	467	*/
	468	uint32_t ext4_validate_encryption_key_size(uint32_t mode, uint32_t size)
	469	{
	470	if (size == ext4_encryption_key_size(mode))
	471	return size;
	472	return 0;
	473	}
28b4c263 TT	474
	475	/*
	476	* Validate dentries for encrypted directories to make sure we aren't
	477	* potentially caching stale data after a key has been added or
	478	* removed.
	479	*/
	480	static int ext4_d_revalidate(struct dentry *dentry, unsigned int flags)
	481	{
3d43bcfe TT	482	struct dentry *dir;
3d43bcfe TT	483	struct ext4_crypt_info *ci;
28b4c263 TT	484	int dir_has_key, cached_with_key;
28b4c263 TT	485
03a8bb0e JK	486	if (flags & LOOKUP_RCU)
	487	return -ECHILD;
	488
3d43bcfe TT	489	dir = dget_parent(dentry);
	490	if (!ext4_encrypted_inode(d_inode(dir))) {
	491	dput(dir);
28b4c263	492	return 0;
3d43bcfe TT	493	}
3d43bcfe TT	494	ci = EXT4_I(d_inode(dir))->i_crypt_info;
28b4c263 TT	495	if (ci && ci->ci_keyring_key &&
	496	(ci->ci_keyring_key->flags & ((1 << KEY_FLAG_INVALIDATED) \|
	497	(1 << KEY_FLAG_REVOKED) \|
	498	(1 << KEY_FLAG_DEAD))))
	499	ci = NULL;
	500
	501	/* this should eventually be an flag in d_flags */
	502	cached_with_key = dentry->d_fsdata != NULL;
	503	dir_has_key = (ci != NULL);
3d43bcfe	504	dput(dir);
28b4c263 TT	505
	506	/*
	507	* If the dentry was cached without the key, and it is a
	508	* negative dentry, it might be a valid name. We can't check
	509	* if the key has since been made available due to locking
	510	* reasons, so we fail the validation so ext4_lookup() can do
	511	* this check.
	512	*
	513	* We also fail the validation if the dentry was created with
	514	* the key present, but we no longer have the key, or vice versa.
	515	*/
	516	if ((!cached_with_key && d_is_negative(dentry)) \|\|
	517	(!cached_with_key && dir_has_key) \|\|
	518	(cached_with_key && !dir_has_key)) {
	519	#if 0 /* Revalidation debug */
	520	char buf[80];
	521	char *cp = simple_dname(dentry, buf, sizeof(buf));
	522
	523	if (IS_ERR(cp))
	524	cp = (char *) "???";
	525	pr_err("revalidate: %s %p %d %d %d\n", cp, dentry->d_fsdata,
	526	cached_with_key, d_is_negative(dentry),
	527	dir_has_key);
	528	#endif
	529	return 0;
	530	}
	531	return 1;
	532	}
	533
	534	const struct dentry_operations ext4_encrypted_d_ops = {
	535	.d_revalidate = ext4_d_revalidate,
	536	};