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fscrypt: introduce fscrypt_encrypt_block_inplace()

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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@linux.ibm.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
This commit is contained in:
Eric Biggers 2019-05-20 09:29:43 -07:00
parent eeacfdc68a
commit 03569f2fb8
3 changed files with 50 additions and 25 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

50
fs/crypto/crypto.c
View File

@ -200,8 +200,7 @@ 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
@ -211,10 +210,9 @@ 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()
*/
@ -225,24 +223,12 @@ 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);
@ -259,6 +245,32 @@ 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.

12
fs/ubifs/crypto.c
View File

@ -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;

13
include/linux/fscrypt.h
View File

@ -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,