From: Eric Biggers <ebiggers@xxxxxxxxxx>
fscrypt_decrypt_page() behaves very differently depending on whether the
filesystem set FS_CFLG_OWN_PAGES in its fscrypt_operations. This makes
the function difficult to understand and document. It also makes it so
that all callers have to provide inode and lblk_num, when fscrypt could
determine these itself for pagecache pages.
Therefore, move the FS_CFLG_OWN_PAGES behavior into a new function
fscrypt_decrypt_block_inplace().
Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
---
fs/crypto/crypto.c | 31 +++++++++++++++++++++++++++----
fs/ubifs/crypto.c | 7 ++++---
include/linux/fscrypt.h | 11 +++++++++++
3 files changed, 42 insertions(+), 7 deletions(-)
diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c
index 7bdb985126d97..2e6fb5e4f7a7f 100644
--- a/fs/crypto/crypto.c
+++ b/fs/crypto/crypto.c
@@ -284,8 +284,7 @@ EXPORT_SYMBOL(fscrypt_encrypt_block_inplace);
/**
* fscrypt_decrypt_page() - Decrypts a page in-place
* @inode: The corresponding inode for the page to decrypt.
- * @page: The page to decrypt. Must be locked in case
- * it is a writeback page (FS_CFLG_OWN_PAGES unset).
+ * @page: The page to decrypt. Must be locked.
* @len: Number of bytes in @page to be decrypted.
* @offs: Start of data in @page.
* @lblk_num: Logical block number.
@@ -299,8 +298,7 @@ EXPORT_SYMBOL(fscrypt_encrypt_block_inplace);
int fscrypt_decrypt_page(const struct inode *inode, struct page *page,
unsigned int len, unsigned int offs, u64 lblk_num)
{
- if (WARN_ON_ONCE(!PageLocked(page) &&
- !(inode->i_sb->s_cop->flags & FS_CFLG_OWN_PAGES)))
+ if (WARN_ON_ONCE(!PageLocked(page)))
return -EINVAL;
return fscrypt_crypt_block(inode, FS_DECRYPT, lblk_num, page, page,
@@ -308,6 +306,31 @@ int fscrypt_decrypt_page(const struct inode *inode, struct page *page,
}
EXPORT_SYMBOL(fscrypt_decrypt_page);
+/**
+ * fscrypt_decrypt_block_inplace() - Decrypt a filesystem block in-place
+ * @inode: The inode to which this block belongs
+ * @page: The page containing the block to decrypt
+ * @len: Size of block to decrypt. Doesn't need to be a multiple of the
+ * fs block size, but must be a multiple of FS_CRYPTO_BLOCK_SIZE.
+ * @offs: Byte offset within @page at which the block to decrypt begins
+ * @lblk_num: Filesystem logical block number of the block, i.e. the 0-based
+ * number of the block within the file
+ *
+ * Decrypt a possibly-compressed filesystem block that is located in an
+ * arbitrary page, not necessarily in the original pagecache page. The @inode
+ * and @lblk_num must be specified, as they can't be determined from @page.
+ *
+ * Return: 0 on success; -errno on failure
+ */
+int fscrypt_decrypt_block_inplace(const struct inode *inode, struct page *page,
+ unsigned int len, unsigned int offs,
+ u64 lblk_num)
+{
+ return fscrypt_crypt_block(inode, FS_DECRYPT, lblk_num, page, page,
+ len, offs, GFP_NOFS);
+}
+EXPORT_SYMBOL(fscrypt_decrypt_block_inplace);
+
/*
* Validate dentries in encrypted directories to make sure we aren't potentially
* caching stale dentries after a key has been added.
diff --git a/fs/ubifs/crypto.c b/fs/ubifs/crypto.c
index 032efdad2e668..22be7aeb96c4f 100644
--- a/fs/ubifs/crypto.c
+++ b/fs/ubifs/crypto.c
@@ -64,10 +64,11 @@ int ubifs_decrypt(const struct inode *inode, struct ubifs_data_node *dn,
}
ubifs_assert(c, dlen <= UBIFS_BLOCK_SIZE);
- err = fscrypt_decrypt_page(inode, virt_to_page(&dn->data), dlen,
- offset_in_page(&dn->data), block);
+ err = fscrypt_decrypt_block_inplace(inode, virt_to_page(&dn->data),
+ dlen, offset_in_page(&dn->data),
+ block);
if (err) {
- ubifs_err(c, "fscrypt_decrypt_page failed: %i", err);
+ ubifs_err(c, "fscrypt_decrypt_block_inplace() failed: %d", err);
return err;
}
*out_len = clen;
diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h
index 39229fcdfac5c..f4890870ca984 100644
--- a/include/linux/fscrypt.h
+++ b/include/linux/fscrypt.h
@@ -114,6 +114,9 @@ extern int fscrypt_encrypt_block_inplace(const struct inode *inode,
gfp_t gfp_flags);
extern int fscrypt_decrypt_page(const struct inode *, struct page *, unsigned int,
unsigned int, u64);
+extern int fscrypt_decrypt_block_inplace(const struct inode *inode,
+ struct page *page, unsigned int len,
+ unsigned int offs, u64 lblk_num);
static inline bool fscrypt_is_bounce_page(struct page *page)
{
@@ -310,6 +313,14 @@ static inline int fscrypt_decrypt_page(const struct inode *inode,
return -EOPNOTSUPP;
}
+static inline int fscrypt_decrypt_block_inplace(const struct inode *inode,
+ struct page *page,
+ unsigned int len,
+ unsigned int offs, u64 lblk_num)
+{
+ return -EOPNOTSUPP;
+}
+
static inline bool fscrypt_is_bounce_page(struct page *page)
{
return false;
--
2.21.0.593.g511ec345e18-goog
