提交 57e5055b 编写于 作者: J Jaegeuk Kim

f2fs crypto: add f2fs encryption facilities

Most of parts were copied from ext4, except:

 - add f2fs_restore_and_release_control_page which returns control page and
   restore control page
 - remove ext4_encrypted_zeroout()
 - remove sbi->s_file_encryption_mode & sbi->s_dir_encryption_mode
 - add f2fs_end_io_crypto_work for mpage_end_io
Signed-off-by: NMichael Halcrow <mhalcrow@google.com>
Signed-off-by: NIldar Muslukhov <ildarm@google.com>
Signed-off-by: NTheodore Ts'o <tytso@mit.edu>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>
上级 f424f664
......@@ -6,4 +6,4 @@ f2fs-$(CONFIG_F2FS_STAT_FS) += debug.o
f2fs-$(CONFIG_F2FS_FS_XATTR) += xattr.o
f2fs-$(CONFIG_F2FS_FS_POSIX_ACL) += acl.o
f2fs-$(CONFIG_F2FS_IO_TRACE) += trace.o
f2fs-$(CONFIG_F2FS_FS_ENCRYPTION) += crypto_policy.o
f2fs-$(CONFIG_F2FS_FS_ENCRYPTION) += crypto_policy.o crypto.o
/*
* 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);
struct workqueue_struct *f2fs_read_workqueue;
static DEFINE_MUTEX(crypto_init);
/**
* 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->bounce_page) {
if (ctx->flags & F2FS_BOUNCE_PAGE_REQUIRES_FREE_ENCRYPT_FL)
__free_page(ctx->bounce_page);
else
mempool_free(ctx->bounce_page, f2fs_bounce_page_pool);
ctx->bounce_page = NULL;
}
ctx->control_page = NULL;
if (ctx->flags & F2FS_CTX_REQUIRES_FREE_ENCRYPT_FL) {
if (ctx->tfm)
crypto_free_tfm(ctx->tfm);
kfree(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_alloc_and_init_crypto_ctx() - Allocates and inits an encryption context
* @mask: The allocation mask.
*
* Return: An allocated and initialized encryption context on success. An error
* value or NULL otherwise.
*/
static struct f2fs_crypto_ctx *f2fs_alloc_and_init_crypto_ctx(gfp_t mask)
{
struct f2fs_crypto_ctx *ctx = kzalloc(sizeof(struct f2fs_crypto_ctx),
mask);
if (!ctx)
return ERR_PTR(-ENOMEM);
return ctx;
}
/**
* 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;
int res = 0;
unsigned long flags;
struct f2fs_crypt_info *ci = F2FS_I(inode)->i_crypt_info;
BUG_ON(ci == NULL);
/*
* 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 = f2fs_alloc_and_init_crypto_ctx(GFP_NOFS);
if (IS_ERR(ctx)) {
res = PTR_ERR(ctx);
goto out;
}
ctx->flags |= F2FS_CTX_REQUIRES_FREE_ENCRYPT_FL;
} else {
ctx->flags &= ~F2FS_CTX_REQUIRES_FREE_ENCRYPT_FL;
}
/*
* Allocate a new Crypto API context if we don't already have
* one or if it isn't the right mode.
*/
BUG_ON(ci->ci_mode == F2FS_ENCRYPTION_MODE_INVALID);
if (ctx->tfm && (ctx->mode != ci->ci_mode)) {
crypto_free_tfm(ctx->tfm);
ctx->tfm = NULL;
ctx->mode = F2FS_ENCRYPTION_MODE_INVALID;
}
if (!ctx->tfm) {
switch (ci->ci_mode) {
case F2FS_ENCRYPTION_MODE_AES_256_XTS:
ctx->tfm = crypto_ablkcipher_tfm(
crypto_alloc_ablkcipher("xts(aes)", 0, 0));
break;
case F2FS_ENCRYPTION_MODE_AES_256_GCM:
/*
* TODO(mhalcrow): AEAD w/ gcm(aes);
* crypto_aead_setauthsize()
*/
ctx->tfm = ERR_PTR(-ENOTSUPP);
break;
default:
BUG();
}
if (IS_ERR_OR_NULL(ctx->tfm)) {
res = PTR_ERR(ctx->tfm);
ctx->tfm = NULL;
goto out;
}
ctx->mode = ci->ci_mode;
}
BUG_ON(ci->ci_size != f2fs_encryption_key_size(ci->ci_mode));
/*
* There shouldn't be a bounce page attached to the crypto
* context at this point.
*/
BUG_ON(ctx->bounce_page);
out:
if (res) {
if (!IS_ERR_OR_NULL(ctx))
f2fs_release_crypto_ctx(ctx);
ctx = ERR_PTR(res);
}
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, work);
struct bio *bio = ctx->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->work, completion_pages);
ctx->bio = bio;
queue_work(f2fs_read_workqueue, &ctx->work);
}
/**
* f2fs_exit_crypto() - Shutdown the f2fs encryption system
*/
void f2fs_exit_crypto(void)
{
struct f2fs_crypto_ctx *pos, *n;
list_for_each_entry_safe(pos, n, &f2fs_free_crypto_ctxs, free_list) {
if (pos->bounce_page) {
if (pos->flags &
F2FS_BOUNCE_PAGE_REQUIRES_FREE_ENCRYPT_FL)
__free_page(pos->bounce_page);
else
mempool_free(pos->bounce_page,
f2fs_bounce_page_pool);
}
if (pos->tfm)
crypto_free_tfm(pos->tfm);
kfree(pos);
}
INIT_LIST_HEAD(&f2fs_free_crypto_ctxs);
if (f2fs_bounce_page_pool)
mempool_destroy(f2fs_bounce_page_pool);
f2fs_bounce_page_pool = NULL;
if (f2fs_read_workqueue)
destroy_workqueue(f2fs_read_workqueue);
f2fs_read_workqueue = NULL;
}
/**
* f2fs_init_crypto() - 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_init_crypto(void)
{
int i, res;
mutex_lock(&crypto_init);
if (f2fs_read_workqueue)
goto already_initialized;
f2fs_read_workqueue = alloc_workqueue("f2fs_crypto", WQ_HIGHPRI, 0);
if (!f2fs_read_workqueue) {
res = -ENOMEM;
goto fail;
}
for (i = 0; i < num_prealloc_crypto_ctxs; i++) {
struct f2fs_crypto_ctx *ctx;
ctx = f2fs_alloc_and_init_crypto_ctx(GFP_KERNEL);
if (IS_ERR(ctx)) {
res = PTR_ERR(ctx);
goto fail;
}
list_add(&ctx->free_list, &f2fs_free_crypto_ctxs);
}
f2fs_bounce_page_pool =
mempool_create_page_pool(num_prealloc_crypto_pages, 0);
if (!f2fs_bounce_page_pool) {
res = -ENOMEM;
goto fail;
}
already_initialized:
mutex_unlock(&crypto_init);
return 0;
fail:
f2fs_exit_crypto();
mutex_unlock(&crypto_init);
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->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_inode_info *fi = F2FS_I(inode);
struct crypto_ablkcipher *atfm = __crypto_ablkcipher_cast(ctx->tfm);
int res = 0;
BUG_ON(!ctx->tfm);
BUG_ON(ctx->mode != fi->i_crypt_info->ci_mode);
if (ctx->mode != F2FS_ENCRYPTION_MODE_AES_256_XTS) {
printk_ratelimited(KERN_ERR
"%s: unsupported crypto algorithm: %d\n",
__func__, ctx->mode);
return -ENOTSUPP;
}
crypto_ablkcipher_clear_flags(atfm, ~0);
crypto_tfm_set_flags(ctx->tfm, CRYPTO_TFM_REQ_WEAK_KEY);
res = crypto_ablkcipher_setkey(atfm, fi->i_crypt_info->ci_raw,
fi->i_crypt_info->ci_size);
if (res) {
printk_ratelimited(KERN_ERR
"%s: crypto_ablkcipher_setkey() failed\n",
__func__);
return res;
}
req = ablkcipher_request_alloc(atfm, 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;
}
/**
* 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_page(GFP_NOFS);
if (!ciphertext_page) {
/*
* This is a potential bottleneck, but at least we'll have
* forward progress.
*/
ciphertext_page = mempool_alloc(f2fs_bounce_page_pool,
GFP_NOFS);
if (WARN_ON_ONCE(!ciphertext_page))
ciphertext_page = mempool_alloc(f2fs_bounce_page_pool,
GFP_NOFS | __GFP_WAIT);
ctx->flags &= ~F2FS_BOUNCE_PAGE_REQUIRES_FREE_ENCRYPT_FL;
} else {
ctx->flags |= F2FS_BOUNCE_PAGE_REQUIRES_FREE_ENCRYPT_FL;
}
ctx->bounce_page = ciphertext_page;
ctx->control_page = plaintext_page;
err = f2fs_page_crypto(ctx, inode, F2FS_ENCRYPT, plaintext_page->index,
plaintext_page, ciphertext_page);
if (err) {
f2fs_release_crypto_ctx(ctx);
return ERR_PTR(err);
}
SetPagePrivate(ciphertext_page);
set_page_private(ciphertext_page, (unsigned long)ctx);
lock_page(ciphertext_page);
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 (!ctx)
return -ENOMEM;
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;
}
......@@ -1962,4 +1962,29 @@ int f2fs_is_child_context_consistent_with_parent(struct inode *,
int f2fs_inherit_context(struct inode *, struct inode *, struct page *);
int f2fs_process_policy(const struct f2fs_encryption_policy *, struct inode *);
int f2fs_get_policy(struct inode *, struct f2fs_encryption_policy *);
/* crypt.c */
extern struct workqueue_struct *f2fs_read_workqueue;
bool f2fs_valid_contents_enc_mode(uint32_t);
uint32_t f2fs_validate_encryption_key_size(uint32_t, uint32_t);
struct f2fs_crypto_ctx *f2fs_get_crypto_ctx(struct inode *);
void f2fs_release_crypto_ctx(struct f2fs_crypto_ctx *);
struct page *f2fs_encrypt(struct inode *, struct page *);
int f2fs_decrypt(struct f2fs_crypto_ctx *, struct page *);
int f2fs_decrypt_one(struct inode *, struct page *);
void f2fs_end_io_crypto_work(struct f2fs_crypto_ctx *, struct bio *);
#ifdef CONFIG_F2FS_FS_ENCRYPTION
void f2fs_restore_and_release_control_page(struct page **);
void f2fs_restore_control_page(struct page *);
int f2fs_init_crypto(void);
void f2fs_exit_crypto(void);
#else
static inline void f2fs_restore_and_release_control_page(struct page **p) { }
static inline void f2fs_restore_control_page(struct page *p) { }
static inline int f2fs_init_crypto(void) { return 0; }
static inline void f2fs_exit_crypto(void) { }
#endif
#endif
......@@ -416,6 +416,9 @@ static struct inode *f2fs_alloc_inode(struct super_block *sb)
/* Will be used by directory only */
fi->i_dir_level = F2FS_SB(sb)->dir_level;
#ifdef CONFIG_F2FS_FS_ENCRYPTION
fi->i_crypt_info = NULL;
#endif
return &fi->vfs_inode;
}
......
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