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>
diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c
index 222a705..e170aa0 100644
--- a/fs/crypto/crypto.c
+++ b/fs/crypto/crypto.c
@@ -149,6 +149,7 @@
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 @@
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 @@
/**
* 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 @@
* 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 @@
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 @@
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 @@
*
* 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 @@
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 @@
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);