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ext4 crypto: add ext4 encryption facilities

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On encrypt, we will re-assign the buffer_heads to point to a bounce
page rather than the control_page (which is the original page to write
that contains the plaintext). The block I/O occurs against the bounce
page.  On write completion, we re-assign the buffer_heads to the
original plaintext page.

On decrypt, we will attach a read completion callback to the bio
struct. This read completion will decrypt the read contents in-place
prior to setting the page up-to-date.

The current encryption mode, AES-256-XTS, lacks cryptographic
integrity. AES-256-GCM is in-plan, but we will need to devise a
mechanism for handling the integrity data.

Signed-off-by: Michael Halcrow <mhalcrow@google.com>
Signed-off-by: Ildar Muslukhov <ildarm@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Michael Halcrow 2015-04-12 00:43:56 -04:00 committed by Theodore Ts'o
parent 9bd8212f98
commit b30ab0e034
6 changed files with 682 additions and 1 deletions
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2
fs/ext4/Makefile
View file

@ -12,4 +12,4 @@ ext4-y := balloc.o bitmap.o dir.o file.o fsync.o ialloc.o inode.o page-io.o \
ext4-$(CONFIG_EXT4_FS_POSIX_ACL) += acl.o
ext4-$(CONFIG_EXT4_FS_SECURITY) += xattr_security.o
ext4-$(CONFIG_EXT4_FS_ENCRYPTION) += crypto_policy.o
ext4-$(CONFIG_EXT4_FS_ENCRYPTION) += crypto_policy.o crypto.o

558
fs/ext4/crypto.c Normal file
View file

@ -0,0 +1,558 @@
/*
* 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/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 "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);
/**
* 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->bounce_page) {
if (ctx->flags & EXT4_BOUNCE_PAGE_REQUIRES_FREE_ENCRYPT_FL)
__free_page(ctx->bounce_page);
else
mempool_free(ctx->bounce_page, ext4_bounce_page_pool);
ctx->bounce_page = NULL;
}
ctx->control_page = NULL;
if (ctx->flags & EXT4_CTX_REQUIRES_FREE_ENCRYPT_FL) {
if (ctx->tfm)
crypto_free_tfm(ctx->tfm);
kfree(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_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 ext4_crypto_ctx *ext4_alloc_and_init_crypto_ctx(gfp_t mask)
{
struct ext4_crypto_ctx *ctx = kzalloc(sizeof(struct ext4_crypto_ctx),
mask);
if (!ctx)
return ERR_PTR(-ENOMEM);
return ctx;
}
/**
* 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)
{
struct ext4_crypto_ctx *ctx = NULL;
int res = 0;
unsigned long flags;
struct ext4_encryption_key *key = &EXT4_I(inode)->i_encryption_key;
if (!ext4_read_workqueue)
ext4_init_crypto();
/*
* 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 = ext4_alloc_and_init_crypto_ctx(GFP_NOFS);
if (IS_ERR(ctx)) {
res = PTR_ERR(ctx);
goto out;
}
ctx->flags |= EXT4_CTX_REQUIRES_FREE_ENCRYPT_FL;
} else {
ctx->flags &= ~EXT4_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(key->mode == EXT4_ENCRYPTION_MODE_INVALID);
if (ctx->tfm && (ctx->mode != key->mode)) {
crypto_free_tfm(ctx->tfm);
ctx->tfm = NULL;
ctx->mode = EXT4_ENCRYPTION_MODE_INVALID;
}
if (!ctx->tfm) {
switch (key->mode) {
case EXT4_ENCRYPTION_MODE_AES_256_XTS:
ctx->tfm = crypto_ablkcipher_tfm(
crypto_alloc_ablkcipher("xts(aes)", 0, 0));
break;
case EXT4_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 = key->mode;
}
BUG_ON(key->size != ext4_encryption_key_size(key->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))
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) {
if (pos->bounce_page) {
if (pos->flags &
EXT4_BOUNCE_PAGE_REQUIRES_FREE_ENCRYPT_FL) {
__free_page(pos->bounce_page);
} else {
mempool_free(pos->bounce_page,
ext4_bounce_page_pool);
}
}
if (pos->tfm)
crypto_free_tfm(pos->tfm);
kfree(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;
}
/**
* 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;
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) {
res = -ENOMEM;
goto fail;
}
for (i = 0; i < num_prealloc_crypto_ctxs; i++) {
struct ext4_crypto_ctx *ctx;
ctx = ext4_alloc_and_init_crypto_ctx(GFP_KERNEL);
if (IS_ERR(ctx)) {
res = PTR_ERR(ctx);
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 ext4_crypto_ctx *ctx,
struct inode *inode,
ext4_direction_t rw,
pgoff_t index,
struct page *src_page,
struct page *dest_page)
{
u8 xts_tweak[EXT4_XTS_TWEAK_SIZE];
struct ablkcipher_request *req = NULL;
DECLARE_EXT4_COMPLETION_RESULT(ecr);
struct scatterlist dst, src;
struct ext4_inode_info *ei = EXT4_I(inode);
struct crypto_ablkcipher *atfm = __crypto_ablkcipher_cast(ctx->tfm);
int res = 0;
BUG_ON(!ctx->tfm);
BUG_ON(ctx->mode != ei->i_encryption_key.mode);
if (ctx->mode != EXT4_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, ei->i_encryption_key.raw,
ei->i_encryption_key.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,
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_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 == EXT4_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;
}
/**
* 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)
{
struct ext4_crypto_ctx *ctx;
struct page *ciphertext_page = NULL;
int err;
BUG_ON(!PageLocked(plaintext_page));
ctx = ext4_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(ext4_bounce_page_pool,
GFP_NOFS);
if (WARN_ON_ONCE(!ciphertext_page)) {
ciphertext_page = mempool_alloc(ext4_bounce_page_pool,
GFP_NOFS | __GFP_WAIT);
}
ctx->flags &= ~EXT4_BOUNCE_PAGE_REQUIRES_FREE_ENCRYPT_FL;
} else {
ctx->flags |= EXT4_BOUNCE_PAGE_REQUIRES_FREE_ENCRYPT_FL;
}
ctx->bounce_page = ciphertext_page;
ctx->control_page = plaintext_page;
err = ext4_page_crypto(ctx, inode, EXT4_ENCRYPT, plaintext_page->index,
plaintext_page, ciphertext_page);
if (err) {
ext4_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;
}
/**
* 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 ext4_crypto_ctx *ctx, struct page *page)
{
BUG_ON(!PageLocked(page));
return ext4_page_crypto(ctx, page->mapping->host,
EXT4_DECRYPT, page->index, page, page);
}
/*
* Convenience function which takes care of allocating and
* deallocating the encryption context
*/
int ext4_decrypt_one(struct inode *inode, struct page *page)
{
int ret;
struct ext4_crypto_ctx *ctx = ext4_get_crypto_ctx(inode);
if (!ctx)
return -ENOMEM;
ret = ext4_decrypt(ctx, page);
ext4_release_crypto_ctx(ctx);
return ret;
}
int ext4_encrypted_zeroout(struct inode *inode, struct ext4_extent *ex)
{
struct ext4_crypto_ctx *ctx;
struct page *ciphertext_page = NULL;
struct bio *bio;
ext4_lblk_t lblk = ex->ee_block;
ext4_fsblk_t pblk = ext4_ext_pblock(ex);
unsigned int len = ext4_ext_get_actual_len(ex);
int err = 0;
BUG_ON(inode->i_sb->s_blocksize != PAGE_CACHE_SIZE);
ctx = ext4_get_crypto_ctx(inode);
if (IS_ERR(ctx))
return PTR_ERR(ctx);
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(ext4_bounce_page_pool,
GFP_NOFS);
if (WARN_ON_ONCE(!ciphertext_page)) {
ciphertext_page = mempool_alloc(ext4_bounce_page_pool,
GFP_NOFS | __GFP_WAIT);
}
ctx->flags &= ~EXT4_BOUNCE_PAGE_REQUIRES_FREE_ENCRYPT_FL;
} else {
ctx->flags |= EXT4_BOUNCE_PAGE_REQUIRES_FREE_ENCRYPT_FL;
}
ctx->bounce_page = ciphertext_page;
while (len--) {
err = ext4_page_crypto(ctx, inode, EXT4_ENCRYPT, lblk,
ZERO_PAGE(0), ciphertext_page);
if (err)
goto errout;
bio = bio_alloc(GFP_KERNEL, 1);
if (!bio) {
err = -ENOMEM;
goto errout;
}
bio->bi_bdev = inode->i_sb->s_bdev;
bio->bi_iter.bi_sector = pblk;
err = bio_add_page(bio, ciphertext_page,
inode->i_sb->s_blocksize, 0);
if (err) {
bio_put(bio);
goto errout;
}
err = submit_bio_wait(WRITE, bio);
if (err)
goto errout;
}
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;
}

8
fs/ext4/crypto_policy.c
View file

@ -52,6 +52,13 @@ static int ext4_create_encryption_context_from_policy(
ctx.format = EXT4_ENCRYPTION_CONTEXT_FORMAT_V1;
memcpy(ctx.master_key_descriptor, policy->master_key_descriptor,
EXT4_KEY_DESCRIPTOR_SIZE);
if (!ext4_valid_contents_enc_mode(policy->contents_encryption_mode)) {
printk(KERN_WARNING
"%s: Invalid contents encryption mode %d\n", __func__,
policy->contents_encryption_mode);
res = -EINVAL;
goto out;
}
ctx.contents_encryption_mode = policy->contents_encryption_mode;
ctx.filenames_encryption_mode = policy->filenames_encryption_mode;
BUILD_BUG_ON(sizeof(ctx.nonce) != EXT4_KEY_DERIVATION_NONCE_SIZE);
@ -60,6 +67,7 @@ static int ext4_create_encryption_context_from_policy(
res = ext4_xattr_set(inode, EXT4_XATTR_INDEX_ENCRYPTION,
EXT4_XATTR_NAME_ENCRYPTION_CONTEXT, &ctx,
sizeof(ctx), 0);
out:
if (!res)
ext4_set_inode_flag(inode, EXT4_INODE_ENCRYPT);
return res;

52
fs/ext4/ext4.h
View file

@ -951,6 +951,11 @@ struct ext4_inode_info {
/* Precomputed uuid+inum+igen checksum for seeding inode checksums */
__u32 i_csum_seed;
#ifdef CONFIG_EXT4_FS_ENCRYPTION
/* Encryption params */
struct ext4_encryption_key i_encryption_key;
#endif
};
/*
@ -1366,6 +1371,12 @@ struct ext4_sb_info {
struct ratelimit_state s_err_ratelimit_state;
struct ratelimit_state s_warning_ratelimit_state;
struct ratelimit_state s_msg_ratelimit_state;
#ifdef CONFIG_EXT4_FS_ENCRYPTION
/* Encryption */
uint32_t s_file_encryption_mode;
uint32_t s_dir_encryption_mode;
#endif
};
static inline struct ext4_sb_info *EXT4_SB(struct super_block *sb)
@ -1481,6 +1492,18 @@ static inline void ext4_clear_state_flags(struct ext4_inode_info *ei)
#define EXT4_SB(sb) (sb)
#endif
/*
* Returns true if the inode is inode is encrypted
*/
static inline int ext4_encrypted_inode(struct inode *inode)
{
#ifdef CONFIG_EXT4_FS_ENCRYPTION
return ext4_test_inode_flag(inode, EXT4_INODE_ENCRYPT);
#else
return 0;
#endif
}
#define NEXT_ORPHAN(inode) EXT4_I(inode)->i_dtime
/*
@ -2026,6 +2049,35 @@ int ext4_process_policy(const struct ext4_encryption_policy *policy,
int ext4_get_policy(struct inode *inode,
struct ext4_encryption_policy *policy);
/* crypto.c */
bool ext4_valid_contents_enc_mode(uint32_t mode);
uint32_t ext4_validate_encryption_key_size(uint32_t mode, uint32_t size);
extern struct workqueue_struct *ext4_read_workqueue;
struct ext4_crypto_ctx *ext4_get_crypto_ctx(struct inode *inode);
void ext4_release_crypto_ctx(struct ext4_crypto_ctx *ctx);
void ext4_restore_control_page(struct page *data_page);
struct page *ext4_encrypt(struct inode *inode,
struct page *plaintext_page);
int ext4_decrypt(struct ext4_crypto_ctx *ctx, struct page *page);
int ext4_decrypt_one(struct inode *inode, struct page *page);
int ext4_encrypted_zeroout(struct inode *inode, struct ext4_extent *ex);
#ifdef CONFIG_EXT4_FS_ENCRYPTION
int ext4_init_crypto(void);
void ext4_exit_crypto(void);
static inline int ext4_sb_has_crypto(struct super_block *sb)
{
return EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_ENCRYPT);
}
#else
static inline int ext4_init_crypto(void) { return 0; }
static inline void ext4_exit_crypto(void) { }
static inline int ext4_sb_has_crypto(struct super_block *sb)
{
return 0;
}
#endif
/* dir.c */
extern int __ext4_check_dir_entry(const char *, unsigned int, struct inode *,
struct file *,

55
fs/ext4/ext4_crypto.h
View file

@ -46,4 +46,59 @@ struct ext4_encryption_context {
char nonce[EXT4_KEY_DERIVATION_NONCE_SIZE];
} __attribute__((__packed__));
/* Encryption parameters */
#define EXT4_XTS_TWEAK_SIZE 16
#define EXT4_AES_128_ECB_KEY_SIZE 16
#define EXT4_AES_256_GCM_KEY_SIZE 32
#define EXT4_AES_256_CBC_KEY_SIZE 32
#define EXT4_AES_256_CTS_KEY_SIZE 32
#define EXT4_AES_256_XTS_KEY_SIZE 64
#define EXT4_MAX_KEY_SIZE 64
struct ext4_encryption_key {
uint32_t mode;
char raw[EXT4_MAX_KEY_SIZE];
uint32_t size;
};
#define EXT4_CTX_REQUIRES_FREE_ENCRYPT_FL 0x00000001
#define EXT4_BOUNCE_PAGE_REQUIRES_FREE_ENCRYPT_FL 0x00000002
struct ext4_crypto_ctx {
struct crypto_tfm *tfm; /* Crypto API context */
struct page *bounce_page; /* Ciphertext page on write path */
struct page *control_page; /* Original page on write path */
struct bio *bio; /* The bio for this context */
struct work_struct work; /* Work queue for read complete path */
struct list_head free_list; /* Free list */
int flags; /* Flags */
int mode; /* Encryption mode for tfm */
};
struct ext4_completion_result {
struct completion completion;
int res;
};
#define DECLARE_EXT4_COMPLETION_RESULT(ecr) \
struct ext4_completion_result ecr = { \
COMPLETION_INITIALIZER((ecr).completion), 0 }
static inline int ext4_encryption_key_size(int mode)
{
switch (mode) {
case EXT4_ENCRYPTION_MODE_AES_256_XTS:
return EXT4_AES_256_XTS_KEY_SIZE;
case EXT4_ENCRYPTION_MODE_AES_256_GCM:
return EXT4_AES_256_GCM_KEY_SIZE;
case EXT4_ENCRYPTION_MODE_AES_256_CBC:
return EXT4_AES_256_CBC_KEY_SIZE;
case EXT4_ENCRYPTION_MODE_AES_256_CTS:
return EXT4_AES_256_CTS_KEY_SIZE;
default:
BUG();
}
return 0;
}
#endif /* _EXT4_CRYPTO_H */

8
fs/ext4/super.c
View file

@ -876,6 +876,9 @@ static struct inode *ext4_alloc_inode(struct super_block *sb)
atomic_set(&ei->i_ioend_count, 0);
atomic_set(&ei->i_unwritten, 0);
INIT_WORK(&ei->i_rsv_conversion_work, ext4_end_io_rsv_work);
#ifdef CONFIG_EXT4_FS_ENCRYPTION
ei->i_encryption_key.mode = EXT4_ENCRYPTION_MODE_INVALID;
#endif
return &ei->vfs_inode;
}
@ -3431,6 +3434,11 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
if (sb->s_bdev->bd_part)
sbi->s_sectors_written_start =
part_stat_read(sb->s_bdev->bd_part, sectors[1]);
#ifdef CONFIG_EXT4_FS_ENCRYPTION
/* Modes of operations for file and directory encryption. */
sbi->s_file_encryption_mode = EXT4_ENCRYPTION_MODE_AES_256_XTS;
sbi->s_dir_encryption_mode = EXT4_ENCRYPTION_MODE_INVALID;
#endif
/* Cleanup superblock name */
for (cp = sb->s_id; (cp = strchr(cp, '/'));)