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Subject[PATCH 05/29] fscrypt: Let fs select encryption index/tweak
Date
From: David Gstir <david@sigma-star.at>

Avoid re-use of page index as tweak for AES-XTS when multiple parts of
same page are encrypted. This will happen on multiple (partial) calls of
fscrypt_encrypt_page on same page.
page->index is only valid for writeback pages.

Signed-off-by: David Gstir <david@sigma-star.at>
Signed-off-by: Richard Weinberger <richard@nod.at>
---
fs/crypto/crypto.c | 11 +++++++----
fs/ext4/inode.c | 4 ++--
fs/ext4/page-io.c | 3 ++-
fs/f2fs/data.c | 5 +++--
include/linux/fscrypto.h | 9 +++++----
5 files changed, 19 insertions(+), 13 deletions(-)

diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c
index f5c5e84ea9db..b6029785714c 100644
--- a/fs/crypto/crypto.c
+++ b/fs/crypto/crypto.c
@@ -218,6 +218,8 @@ static struct page *alloc_bounce_page(struct fscrypt_ctx *ctx, gfp_t gfp_flags)
* @plaintext_page: The page to encrypt. Must be locked.
* @plaintext_len: Length of plaintext within page
* @plaintext_offset: Offset of plaintext within page
+ * @index: Index for encryption. This is mainly the page index, but
+ * but might be different for multiple calls on same page.
* @gfp_flags: The gfp flag for memory allocation
*
* Encrypts plaintext_page using the ctx encryption context. If
@@ -235,7 +237,7 @@ struct page *fscrypt_encrypt_page(const struct inode *inode,
struct page *plaintext_page,
unsigned int plaintext_len,
unsigned int plaintext_offset,
- gfp_t gfp_flags)
+ pgoff_t index, gfp_t gfp_flags)

{
struct fscrypt_ctx *ctx;
@@ -256,7 +258,7 @@ struct page *fscrypt_encrypt_page(const struct inode *inode,
}

ctx->w.control_page = plaintext_page;
- err = do_page_crypto(inode, FS_ENCRYPT, plaintext_page->index,
+ err = do_page_crypto(inode, FS_ENCRYPT, index,
plaintext_page, ciphertext_page,
plaintext_len, plaintext_offset,
gfp_flags);
@@ -283,6 +285,7 @@ EXPORT_SYMBOL(fscrypt_encrypt_page);
* @page: The page to decrypt. Must be locked.
* @len: Number of bytes in @page to be decrypted.
* @offs: Start of data in @page.
+ * @index: Index for encryption.
*
* Decrypts page in-place using the ctx encryption context.
*
@@ -291,7 +294,7 @@ EXPORT_SYMBOL(fscrypt_encrypt_page);
* Return: Zero on success, non-zero otherwise.
*/
int fscrypt_decrypt_page(const struct inode *inode, struct page *page,
- unsigned int len, unsigned int offs)
+ unsigned int len, unsigned int offs, pgoff_t index)
{
return do_page_crypto(inode, FS_DECRYPT, page->index, page, page, len, offs,
GFP_NOFS);
@@ -430,7 +433,7 @@ 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,
- PAGE_SIZE, 0);
+ PAGE_SIZE, 0, page->index);

if (ret) {
WARN_ON_ONCE(1);
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 1d498c5e2990..1485ac273bfb 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1167,7 +1167,7 @@ static int ext4_block_write_begin(struct page *page, loff_t pos, unsigned len,
page_zero_new_buffers(page, from, to);
else if (decrypt)
err = fscrypt_decrypt_page(page->mapping->host, page,
- PAGE_SIZE, 0);
+ PAGE_SIZE, 0, page->index);
return err;
}
#endif
@@ -3746,7 +3746,7 @@ static int __ext4_block_zero_page_range(handle_t *handle,
BUG_ON(blocksize != PAGE_SIZE);
BUG_ON(!PageLocked(page));
WARN_ON_ONCE(fscrypt_decrypt_page(page->mapping->host,
- page, PAGE_SIZE, 0));
+ page, PAGE_SIZE, 0, page->index));
}
}
if (ext4_should_journal_data(inode)) {
diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
index 3d1d3d0f4303..902a3e3059b3 100644
--- a/fs/ext4/page-io.c
+++ b/fs/ext4/page-io.c
@@ -470,7 +470,8 @@ 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, PAGE_SIZE, 0, gfp_flags);
+ data_page = fscrypt_encrypt_page(inode, page, PAGE_SIZE, 0,
+ page->index, gfp_flags);
if (IS_ERR(data_page)) {
ret = PTR_ERR(data_page);
if (ret == -ENOMEM && wbc->sync_mode == WB_SYNC_ALL) {
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index fac207254e8d..435590c4b341 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -1196,8 +1196,9 @@ int do_write_data_page(struct f2fs_io_info *fio)
retry_encrypt:
BUG_ON(!PageLocked(fio->page));
fio->encrypted_page = fscrypt_encrypt_page(inode, fio->page,
- PAGE_SIZE, 0,
- gfp_flags);
+ PAGE_SIZE, 0,
+ fio->page->index,
+ gfp_flags);
if (IS_ERR(fio->encrypted_page)) {
err = PTR_ERR(fio->encrypted_page);
if (err == -ENOMEM) {
diff --git a/include/linux/fscrypto.h b/include/linux/fscrypto.h
index e9be944a324c..98c71e973a96 100644
--- a/include/linux/fscrypto.h
+++ b/include/linux/fscrypto.h
@@ -250,9 +250,9 @@ extern struct fscrypt_ctx *fscrypt_get_ctx(const struct inode *, gfp_t);
extern void fscrypt_release_ctx(struct fscrypt_ctx *);
extern struct page *fscrypt_encrypt_page(const struct inode *, struct page *,
unsigned int, unsigned int,
- gfp_t);
+ pgoff_t, gfp_t);
extern int fscrypt_decrypt_page(const struct inode *, struct page *, unsigned int,
- unsigned int);
+ unsigned int, pgoff_t);
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 *);
@@ -299,13 +299,14 @@ static inline struct page *fscrypt_notsupp_encrypt_page(const struct inode *i,
struct page *p,
unsigned int len,
unsigned int offs,
- gfp_t f)
+ pgoff_t index, gfp_t f)
{
return ERR_PTR(-EOPNOTSUPP);
}

static inline int fscrypt_notsupp_decrypt_page(const struct inode *i, struct page *p,
- unsigned int len, unsigned int offs)
+ unsigned int len, unsigned int offs,
+ pgoff_t index)
{
return -EOPNOTSUPP;
}
--
2.7.3
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