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fscrypt: Enable partial page encryption 

Not all filesystems work on full pages, thus we should allow them to
hand partial pages to fscrypt for en/decryption.

Signed-off-by: David Gstir <david@sigma-star.at>
Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
zero-colors
David Gstir 2016-11-13 22:20:46 +01:00 committed by Theodore Ts'o
parent b50f7b268b
commit 7821d4dd45
5 changed files with 44 additions and 24 deletions
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42
fs/crypto/crypto.c
View File

@ -149,6 +149,7 @@ typedef enum {
static int do_page_crypto(struct inode *inode,
fscrypt_direction_t rw, pgoff_t index,
struct page *src_page, struct page *dest_page,
unsigned int src_len, unsigned int src_offset,
gfp_t gfp_flags)
{
struct {
@ -179,10 +180,10 @@ static int do_page_crypto(struct inode *inode,
memset(xts_tweak.padding, 0, sizeof(xts_tweak.padding));
sg_init_table(&dst, 1);
sg_set_page(&dst, dest_page, PAGE_SIZE, 0);
sg_set_page(&dst, dest_page, src_len, src_offset);
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);
sg_set_page(&src, src_page, src_len, src_offset);
skcipher_request_set_crypt(req, &src, &dst, src_len, &xts_tweak);
if (rw == FS_DECRYPT)
res = crypto_skcipher_decrypt(req);
else
@ -213,9 +214,11 @@ static struct page *alloc_bounce_page(struct fscrypt_ctx *ctx, gfp_t gfp_flags)
/**
* fscypt_encrypt_page() - Encrypts a page
* @inode: The inode for which the encryption should take place
* @plaintext_page: The page to encrypt. Must be locked.
* @gfp_flags: The gfp flag for memory allocation
* @inode: The inode for which the encryption should take place
* @plaintext_page: The page to encrypt. Must be locked.
* @plaintext_len: Length of plaintext within page
* @plaintext_offset: Offset of plaintext within page
* @gfp_flags: The gfp flag for memory allocation
*
* Encrypts plaintext_page using the ctx encryption context. If
* the filesystem supports it, encryption is performed in-place, otherwise a
@ -229,13 +232,17 @@ static struct page *alloc_bounce_page(struct fscrypt_ctx *ctx, gfp_t gfp_flags)
* error value or NULL.
*/
struct page *fscrypt_encrypt_page(struct inode *inode,
struct page *plaintext_page, gfp_t gfp_flags)
struct page *plaintext_page,
unsigned int plaintext_len,
unsigned int plaintext_offset,
gfp_t gfp_flags)
{
struct fscrypt_ctx *ctx;
struct page *ciphertext_page = plaintext_page;
int err;
BUG_ON(!PageLocked(plaintext_page));
BUG_ON(plaintext_len % FS_CRYPTO_BLOCK_SIZE != 0);
ctx = fscrypt_get_ctx(inode, gfp_flags);
if (IS_ERR(ctx))
@ -251,6 +258,7 @@ struct page *fscrypt_encrypt_page(struct inode *inode,
ctx->w.control_page = plaintext_page;
err = do_page_crypto(inode, FS_ENCRYPT, plaintext_page->index,
plaintext_page, ciphertext_page,
plaintext_len, plaintext_offset,
gfp_flags);
if (err) {
ciphertext_page = ERR_PTR(err);
@ -270,9 +278,11 @@ errout:
EXPORT_SYMBOL(fscrypt_encrypt_page);
/**
* f2crypt_decrypt_page() - Decrypts a page in-place
* @inode: The encrypted inode to decrypt.
* fscrypt_decrypt_page() - Decrypts a page in-place
* @inode: Encrypted inode to decrypt.
* @page: The page to decrypt. Must be locked.
* @len: Number of bytes in @page to be decrypted.
* @offs: Start of data in @page.
*
* Decrypts page in-place using the ctx encryption context.
*
@ -280,11 +290,10 @@ EXPORT_SYMBOL(fscrypt_encrypt_page);
*
* Return: Zero on success, non-zero otherwise.
*/
int fscrypt_decrypt_page(struct inode *inode, struct page *page)
int fscrypt_decrypt_page(struct inode *inode, struct page *page,
unsigned int len, unsigned int offs)
{
BUG_ON(!PageLocked(page));
return do_page_crypto(inode, FS_DECRYPT, page->index, page, page,
return do_page_crypto(inode, FS_DECRYPT, page->index, page, page, len, offs,
GFP_NOFS);
}
EXPORT_SYMBOL(fscrypt_decrypt_page);
@ -312,7 +321,7 @@ int fscrypt_zeroout_range(struct inode *inode, pgoff_t lblk,
while (len--) {
err = do_page_crypto(inode, FS_ENCRYPT, lblk,
ZERO_PAGE(0), ciphertext_page,
GFP_NOFS);
PAGE_SIZE, 0, GFP_NOFS);
if (err)
goto errout;
@ -420,7 +429,8 @@ static void completion_pages(struct work_struct *work)
bio_for_each_segment_all(bv, bio, i) {
struct page *page = bv->bv_page;
int ret = fscrypt_decrypt_page(page->mapping->host, page);
int ret = fscrypt_decrypt_page(page->mapping->host, page,
PAGE_SIZE, 0);
if (ret) {
WARN_ON_ONCE(1);

6
fs/ext4/inode.c
View File

@ -1166,7 +1166,8 @@ static int ext4_block_write_begin(struct page *page, loff_t pos, unsigned len,
if (unlikely(err))
page_zero_new_buffers(page, from, to);
else if (decrypt)
err = fscrypt_decrypt_page(page->mapping->host, page);
err = fscrypt_decrypt_page(page->mapping->host, page,
PAGE_SIZE, 0);
return err;
}
#endif
@ -3743,8 +3744,9 @@ static int __ext4_block_zero_page_range(handle_t *handle,
/* We expect the key to be set. */
BUG_ON(!fscrypt_has_encryption_key(inode));
BUG_ON(blocksize != PAGE_SIZE);
BUG_ON(!PageLocked(page));
WARN_ON_ONCE(fscrypt_decrypt_page(page->mapping->host,
page));
page, PAGE_SIZE, 0));
}
}
if (ext4_should_journal_data(inode)) {

2
fs/ext4/page-io.c
View File

@ -470,7 +470,7 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
gfp_t gfp_flags = GFP_NOFS;
retry_encrypt:
data_page = fscrypt_encrypt_page(inode, page, gfp_flags);
data_page = fscrypt_encrypt_page(inode, page, PAGE_SIZE, 0, gfp_flags);
if (IS_ERR(data_page)) {
ret = PTR_ERR(data_page);
if (ret == -ENOMEM && wbc->sync_mode == WB_SYNC_ALL) {

2
fs/f2fs/data.c
View File

@ -1194,7 +1194,9 @@ int do_write_data_page(struct f2fs_io_info *fio)
f2fs_wait_on_encrypted_page_writeback(F2FS_I_SB(inode),
fio->old_blkaddr);
retry_encrypt:
BUG_ON(!PageLocked(fio->page));
fio->encrypted_page = fscrypt_encrypt_page(inode, fio->page,
PAGE_SIZE, 0,
gfp_flags);
if (IS_ERR(fio->encrypted_page)) {
err = PTR_ERR(fio->encrypted_page);

16
include/linux/fscrypto.h
View File

@ -248,8 +248,11 @@ int fscrypt_initialize(void);
extern struct fscrypt_ctx *fscrypt_get_ctx(struct inode *, gfp_t);
extern void fscrypt_release_ctx(struct fscrypt_ctx *);
extern struct page *fscrypt_encrypt_page(struct inode *, struct page *, gfp_t);
extern int fscrypt_decrypt_page(struct inode *, struct page *);
extern struct page *fscrypt_encrypt_page(struct inode *, struct page *,
unsigned int, unsigned int,
gfp_t);
extern int fscrypt_decrypt_page(struct inode *, struct page *, unsigned int,
unsigned int);
extern void fscrypt_decrypt_bio_pages(struct fscrypt_ctx *, struct bio *);
extern void fscrypt_pullback_bio_page(struct page **, bool);
extern void fscrypt_restore_control_page(struct page *);
@ -293,13 +296,16 @@ static inline void fscrypt_notsupp_release_ctx(struct fscrypt_ctx *c)
}
static inline struct page *fscrypt_notsupp_encrypt_page(struct inode *i,
struct page *p, gfp_t f)
struct page *p,
unsigned int len,
unsigned int offs,
gfp_t f)
{
return ERR_PTR(-EOPNOTSUPP);
}
static inline int fscrypt_notsupp_decrypt_page(struct inode *i,
struct page *p)
static inline int fscrypt_notsupp_decrypt_page(struct inode *i, struct page *p,
unsigned int len, unsigned int offs)
{
return -EOPNOTSUPP;
}