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 222a70520565cbab32a8a480b2ec4a3540f5f700..e170aa05011d6b2b18afead4cf0319271361d90a 100644 (file)
--- a/fs/crypto/crypto.c
+++ b/fs/crypto/crypto.c
@@ -149,6 +149,7 @@ typedef enum {
 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 @@ static int do_page_crypto(struct inode *inode,
        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 @@ static struct page *alloc_bounce_page(struct fscrypt_ctx *ctx, gfp_t gfp_flags)
 
 /**
  * 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 @@ static struct page *alloc_bounce_page(struct fscrypt_ctx *ctx, gfp_t gfp_flags)
  * 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 @@ struct page *fscrypt_encrypt_page(struct inode *inode,
        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 @@ errout:
 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 @@ EXPORT_SYMBOL(fscrypt_encrypt_page);
  *
  * 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 @@ int fscrypt_zeroout_range(struct inode *inode, pgoff_t lblk,
        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 @@ 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);
+               int ret = fscrypt_decrypt_page(page->mapping->host, page,
+                               PAGE_SIZE, 0);
 
                if (ret) {
                        WARN_ON_ONCE(1);

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 4b7b842ec024b42aef0edd8b9106ccced80d3ba4..1d498c5e2990e0cc013ec510f7c463da2945bdac 100644 (file)
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1166,7 +1166,8 @@ static int ext4_block_write_begin(struct page *page, loff_t pos, unsigned len,
        if (unlikely(err))
                page_zero_new_buffers(page, from, to);
        else if (decrypt)
-               err = fscrypt_decrypt_page(page->mapping->host, page);
+               err = fscrypt_decrypt_page(page->mapping->host, page,
+                               PAGE_SIZE, 0);
        return err;
 }
 #endif
@@ -3743,8 +3744,9 @@ static int __ext4_block_zero_page_range(handle_t *handle,
                        /* We expect the key to be set. */
                        BUG_ON(!fscrypt_has_encryption_key(inode));
                        BUG_ON(blocksize != PAGE_SIZE);
+                       BUG_ON(!PageLocked(page));
                        WARN_ON_ONCE(fscrypt_decrypt_page(page->mapping->host,
-                                               page));
+                                               page, PAGE_SIZE, 0));
                }
        }
        if (ext4_should_journal_data(inode)) {

diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
index 0094923e5ebf56a6a65198cf5a7040078b73240a..3d1d3d0f4303aa28ca334dc35931b524eadc1efc 100644 (file)
--- a/fs/ext4/page-io.c
+++ b/fs/ext4/page-io.c
@@ -470,7 +470,7 @@ 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, gfp_flags);
+               data_page = fscrypt_encrypt_page(inode, page, PAGE_SIZE, 0, 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 9ae194fd2fdb81cbc54bfed9220da527d6b21a89..fac207254e8dd2bcb1a6d8e441795af6ca314977 100644 (file)
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -1194,7 +1194,9 @@ int do_write_data_page(struct f2fs_io_info *fio)
                f2fs_wait_on_encrypted_page_writeback(F2FS_I_SB(inode),
                                                        fio->old_blkaddr);
 retry_encrypt:
+               BUG_ON(!PageLocked(fio->page));
                fio->encrypted_page = fscrypt_encrypt_page(inode, fio->page,
+                                                               PAGE_SIZE, 0,
                                                                gfp_flags);
                if (IS_ERR(fio->encrypted_page)) {
                        err = PTR_ERR(fio->encrypted_page);

diff --git a/include/linux/fscrypto.h b/include/linux/fscrypto.h
index 8be8e9657c631fcd1597937c7308070a497cfece..e05931272cea4cb2ffc3be4db35702bf95830c6f 100644 (file)
--- a/include/linux/fscrypto.h
+++ b/include/linux/fscrypto.h
@@ -248,8 +248,11 @@ int fscrypt_initialize(void);
 
 extern struct fscrypt_ctx *fscrypt_get_ctx(struct inode *, gfp_t);
 extern void fscrypt_release_ctx(struct fscrypt_ctx *);
-extern struct page *fscrypt_encrypt_page(struct inode *, struct page *, gfp_t);
-extern int fscrypt_decrypt_page(struct inode *, struct page *);
+extern struct page *fscrypt_encrypt_page(struct inode *, struct page *,
+                                               unsigned int, unsigned int,
+                                               gfp_t);
+extern int fscrypt_decrypt_page(struct inode *, struct page *, unsigned int,
+                               unsigned int);
 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 *);
@@ -293,13 +296,16 @@ static inline void fscrypt_notsupp_release_ctx(struct fscrypt_ctx *c)
 }
 
 static inline struct page *fscrypt_notsupp_encrypt_page(struct inode *i,
-                                               struct page *p, gfp_t f)
+                                               struct page *p,
+                                               unsigned int len,
+                                               unsigned int offs,
+                                               gfp_t f)
 {
        return ERR_PTR(-EOPNOTSUPP);
 }
 
-static inline int fscrypt_notsupp_decrypt_page(struct inode *i,
-                                               struct page *p)
+static inline int fscrypt_notsupp_decrypt_page(struct inode *i, struct page *p,
+                                               unsigned int len, unsigned int offs)
 {
        return -EOPNOTSUPP;
 }