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Message-Id: <20190520162952.156212-6-ebiggers@kernel.org>
Date: Mon, 20 May 2019 09:29:43 -0700
From: Eric Biggers <ebiggers@...nel.org>
To: linux-fscrypt@...r.kernel.org
Cc: linux-ext4@...r.kernel.org, linux-f2fs-devel@...ts.sourceforge.net,
linux-mtd@...ts.infradead.org,
Chandan Rajendra <chandan@...ux.ibm.com>
Subject: [PATCH v2 05/14] fscrypt: introduce fscrypt_encrypt_block_inplace()
From: Eric Biggers <ebiggers@...gle.com>
fscrypt_encrypt_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_encrypt_block_inplace().
This is in preparation for allowing encryption on ext4 filesystems with
blocksize != PAGE_SIZE.
Reviewed-by: Chandan Rajendra <chandan@...ux.ibm.com>
Signed-off-by: Eric Biggers <ebiggers@...gle.com>
---
fs/crypto/crypto.c | 50 +++++++++++++++++++++++++----------------
fs/ubifs/crypto.c | 12 +++++-----
include/linux/fscrypt.h | 13 +++++++++++
3 files changed, 50 insertions(+), 25 deletions(-)
diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c
index 9cda0147fca95..6877b7c6165de 100644
--- a/fs/crypto/crypto.c
+++ b/fs/crypto/crypto.c
@@ -199,8 +199,7 @@ int fscrypt_crypt_block(const struct inode *inode, fscrypt_direction_t rw,
/**
* fscypt_encrypt_page() - Encrypts a page
* @inode: The inode for which the encryption should take place
- * @page: The page to encrypt. Must be locked for bounce-page
- * encryption.
+ * @page: The page to encrypt. Must be locked.
* @len: Length of data to encrypt in @page and encrypted
* data in returned page.
* @offs: Offset of data within @page and returned
@@ -210,10 +209,9 @@ int fscrypt_crypt_block(const struct inode *inode, fscrypt_direction_t rw,
* previously written data.
* @gfp_flags: The gfp flag for memory allocation
*
- * Encrypts @page. If the filesystem set FS_CFLG_OWN_PAGES, then the data is
- * encrypted in-place and @page is returned. Else, a bounce page is allocated,
- * the data is encrypted into the bounce page, and the bounce page is returned.
- * The caller is responsible for calling fscrypt_free_bounce_page().
+ * Encrypts @page. A bounce page is allocated, the data is encrypted into the
+ * bounce page, and the bounce page is returned. The caller is responsible for
+ * calling fscrypt_free_bounce_page().
*
* Return: A page containing the encrypted data on success, else an ERR_PTR()
*/
@@ -224,24 +222,12 @@ struct page *fscrypt_encrypt_page(const struct inode *inode,
u64 lblk_num, gfp_t gfp_flags)
{
- struct page *ciphertext_page = page;
+ struct page *ciphertext_page;
int err;
- if (inode->i_sb->s_cop->flags & FS_CFLG_OWN_PAGES) {
- /* with inplace-encryption we just encrypt the page */
- err = fscrypt_crypt_block(inode, FS_ENCRYPT, lblk_num, page,
- ciphertext_page, len, offs,
- gfp_flags);
- if (err)
- return ERR_PTR(err);
-
- return ciphertext_page;
- }
-
if (WARN_ON_ONCE(!PageLocked(page)))
return ERR_PTR(-EINVAL);
- /* The encryption operation will require a bounce page. */
ciphertext_page = fscrypt_alloc_bounce_page(gfp_flags);
if (!ciphertext_page)
return ERR_PTR(-ENOMEM);
@@ -258,6 +244,32 @@ struct page *fscrypt_encrypt_page(const struct inode *inode,
}
EXPORT_SYMBOL(fscrypt_encrypt_page);
+/**
+ * fscrypt_encrypt_block_inplace() - Encrypt a filesystem block in-place
+ * @inode: The inode to which this block belongs
+ * @page: The page containing the block to encrypt
+ * @len: Size of block to encrypt. 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 encrypt begins
+ * @lblk_num: Filesystem logical block number of the block, i.e. the 0-based
+ * number of the block within the file
+ * @gfp_flags: Memory allocation flags
+ *
+ * Encrypt 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_encrypt_block_inplace(const struct inode *inode, struct page *page,
+ unsigned int len, unsigned int offs,
+ u64 lblk_num, gfp_t gfp_flags)
+{
+ return fscrypt_crypt_block(inode, FS_ENCRYPT, lblk_num, page, page,
+ len, offs, gfp_flags);
+}
+EXPORT_SYMBOL(fscrypt_encrypt_block_inplace);
+
/**
* fscrypt_decrypt_page() - Decrypts a page in-place
* @inode: The corresponding inode for the page to decrypt.
diff --git a/fs/ubifs/crypto.c b/fs/ubifs/crypto.c
index 4aaedf2d7f442..032efdad2e668 100644
--- a/fs/ubifs/crypto.c
+++ b/fs/ubifs/crypto.c
@@ -29,8 +29,8 @@ int ubifs_encrypt(const struct inode *inode, struct ubifs_data_node *dn,
{
struct ubifs_info *c = inode->i_sb->s_fs_info;
void *p = &dn->data;
- struct page *ret;
unsigned int pad_len = round_up(in_len, UBIFS_CIPHER_BLOCK_SIZE);
+ int err;
ubifs_assert(c, pad_len <= *out_len);
dn->compr_size = cpu_to_le16(in_len);
@@ -39,11 +39,11 @@ int ubifs_encrypt(const struct inode *inode, struct ubifs_data_node *dn,
if (pad_len != in_len)
memset(p + in_len, 0, pad_len - in_len);
- ret = fscrypt_encrypt_page(inode, virt_to_page(&dn->data), pad_len,
- offset_in_page(&dn->data), block, GFP_NOFS);
- if (IS_ERR(ret)) {
- ubifs_err(c, "fscrypt_encrypt_page failed: %ld", PTR_ERR(ret));
- return PTR_ERR(ret);
+ err = fscrypt_encrypt_block_inplace(inode, virt_to_page(p), pad_len,
+ offset_in_page(p), block, GFP_NOFS);
+ if (err) {
+ ubifs_err(c, "fscrypt_encrypt_block_inplace() failed: %d", err);
+ return err;
}
*out_len = pad_len;
diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h
index 1c7287f146a98..a9b2d26e615d5 100644
--- a/include/linux/fscrypt.h
+++ b/include/linux/fscrypt.h
@@ -106,6 +106,10 @@ extern void fscrypt_release_ctx(struct fscrypt_ctx *);
extern struct page *fscrypt_encrypt_page(const struct inode *, struct page *,
unsigned int, unsigned int,
u64, gfp_t);
+extern int fscrypt_encrypt_block_inplace(const struct inode *inode,
+ struct page *page, unsigned int len,
+ unsigned int offs, u64 lblk_num,
+ gfp_t gfp_flags);
extern int fscrypt_decrypt_page(const struct inode *, struct page *, unsigned int,
unsigned int, u64);
@@ -293,6 +297,15 @@ static inline struct page *fscrypt_encrypt_page(const struct inode *inode,
return ERR_PTR(-EOPNOTSUPP);
}
+static inline int fscrypt_encrypt_block_inplace(const struct inode *inode,
+ struct page *page,
+ unsigned int len,
+ unsigned int offs, u64 lblk_num,
+ gfp_t gfp_flags)
+{
+ return -EOPNOTSUPP;
+}
+
static inline int fscrypt_decrypt_page(const struct inode *inode,
struct page *page,
unsigned int len, unsigned int offs,
--
2.21.0.1020.gf2820cf01a-goog
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