From 7821d4dd4589ce5af54f3e46d04a29439ba3c2e5 Mon Sep 17 00:00:00 2001 From: David Gstir Date: Sun, 13 Nov 2016 22:20:46 +0100 Subject: 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 Signed-off-by: Richard Weinberger Signed-off-by: Theodore Ts'o --- fs/crypto/crypto.c | 42 ++++++++++++++++++++++++++---------------- 1 file changed, 26 insertions(+), 16 deletions(-) (limited to 'fs/crypto/crypto.c') diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c index 222a70520565..e170aa05011d 100644 --- 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); -- cgit v1.2.3