linux-stable/fs/ext4/crypto.c
Kirill A. Shutemov 09cbfeaf1a mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros
PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} macros were introduced *long* time
ago with promise that one day it will be possible to implement page
cache with bigger chunks than PAGE_SIZE.

This promise never materialized.  And unlikely will.

We have many places where PAGE_CACHE_SIZE assumed to be equal to
PAGE_SIZE.  And it's constant source of confusion on whether
PAGE_CACHE_* or PAGE_* constant should be used in a particular case,
especially on the border between fs and mm.

Global switching to PAGE_CACHE_SIZE != PAGE_SIZE would cause to much
breakage to be doable.

Let's stop pretending that pages in page cache are special.  They are
not.

The changes are pretty straight-forward:

 - <foo> << (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>;

 - <foo> >> (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>;

 - PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} -> PAGE_{SIZE,SHIFT,MASK,ALIGN};

 - page_cache_get() -> get_page();

 - page_cache_release() -> put_page();

This patch contains automated changes generated with coccinelle using
script below.  For some reason, coccinelle doesn't patch header files.
I've called spatch for them manually.

The only adjustment after coccinelle is revert of changes to
PAGE_CAHCE_ALIGN definition: we are going to drop it later.

There are few places in the code where coccinelle didn't reach.  I'll
fix them manually in a separate patch.  Comments and documentation also
will be addressed with the separate patch.

virtual patch

@@
expression E;
@@
- E << (PAGE_CACHE_SHIFT - PAGE_SHIFT)
+ E

@@
expression E;
@@
- E >> (PAGE_CACHE_SHIFT - PAGE_SHIFT)
+ E

@@
@@
- PAGE_CACHE_SHIFT
+ PAGE_SHIFT

@@
@@
- PAGE_CACHE_SIZE
+ PAGE_SIZE

@@
@@
- PAGE_CACHE_MASK
+ PAGE_MASK

@@
expression E;
@@
- PAGE_CACHE_ALIGN(E)
+ PAGE_ALIGN(E)

@@
expression E;
@@
- page_cache_get(E)
+ get_page(E)

@@
expression E;
@@
- page_cache_release(E)
+ put_page(E)

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-04-04 10:41:08 -07:00

523 lines
14 KiB
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 "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)
{
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_NOFS);
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)
{
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_NOFS);
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)
{
ctx->w.bounce_page = mempool_alloc(ext4_bounce_page_pool, GFP_NOWAIT);
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)
{
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_bounce_page(ctx);
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);
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);
}
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);
if (IS_ERR(ctx))
return PTR_ERR(ctx);
ciphertext_page = alloc_bounce_page(ctx);
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);
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 << (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 inode *dir = d_inode(dentry->d_parent);
struct ext4_crypt_info *ci = EXT4_I(dir)->i_crypt_info;
int dir_has_key, cached_with_key;
if (!ext4_encrypted_inode(dir))
return 0;
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);
/*
* 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,
};