From 51e4e3153ebc32d3280d5d17418ae6f1a44f1ec1 Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Fri, 27 Jan 2023 14:25:14 -0800 Subject: [PATCH] fscrypt: support decrypting data from large folios Try to make the filesystem-level decryption functions in fs/crypto/ aware of large folios. This includes making fscrypt_decrypt_bio() support the case where the bio contains large folios, and making fscrypt_decrypt_pagecache_blocks() take a folio instead of a page. There's no way to actually test this with large folios yet, but I've tested that this doesn't cause any regressions. Note that this patch just handles *decryption*, not encryption which will be a little more difficult. Signed-off-by: Eric Biggers Reviewed-by: Matthew Wilcox (Oracle) Link: https://lore.kernel.org/r/20230127224202.355629-1-ebiggers@kernel.org --- Documentation/filesystems/fscrypt.rst | 4 ++-- fs/buffer.c | 4 ++-- fs/crypto/bio.c | 10 ++++------ fs/crypto/crypto.c | 28 +++++++++++++++------------- fs/ext4/inode.c | 6 ++++-- include/linux/fscrypt.h | 9 ++++----- 6 files changed, 31 insertions(+), 30 deletions(-) diff --git a/Documentation/filesystems/fscrypt.rst b/Documentation/filesystems/fscrypt.rst index ef18338..eccd327 100644 --- a/Documentation/filesystems/fscrypt.rst +++ b/Documentation/filesystems/fscrypt.rst @@ -1277,8 +1277,8 @@ the file contents themselves, as described below: For the read path (->read_folio()) of regular files, filesystems can read the ciphertext into the page cache and decrypt it in-place. The -page lock must be held until decryption has finished, to prevent the -page from becoming visible to userspace prematurely. +folio lock must be held until decryption has finished, to prevent the +folio from becoming visible to userspace prematurely. For the write path (->writepage()) of regular files, filesystems cannot encrypt data in-place in the page cache, since the cached diff --git a/fs/buffer.c b/fs/buffer.c index 8499c79..623e77d 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -331,8 +331,8 @@ static void decrypt_bh(struct work_struct *work) struct buffer_head *bh = ctx->bh; int err; - err = fscrypt_decrypt_pagecache_blocks(bh->b_page, bh->b_size, - bh_offset(bh)); + err = fscrypt_decrypt_pagecache_blocks(page_folio(bh->b_page), + bh->b_size, bh_offset(bh)); if (err == 0 && need_fsverity(bh)) { /* * We use different work queues for decryption and for verity diff --git a/fs/crypto/bio.c b/fs/crypto/bio.c index 1b44031..d57d0a0 100644 --- a/fs/crypto/bio.c +++ b/fs/crypto/bio.c @@ -30,13 +30,11 @@ */ bool fscrypt_decrypt_bio(struct bio *bio) { - struct bio_vec *bv; - struct bvec_iter_all iter_all; + struct folio_iter fi; - bio_for_each_segment_all(bv, bio, iter_all) { - struct page *page = bv->bv_page; - int err = fscrypt_decrypt_pagecache_blocks(page, bv->bv_len, - bv->bv_offset); + bio_for_each_folio_all(fi, bio) { + int err = fscrypt_decrypt_pagecache_blocks(fi.folio, fi.length, + fi.offset); if (err) { bio->bi_status = errno_to_blk_status(err); diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c index e78be66..bf64247 100644 --- a/fs/crypto/crypto.c +++ b/fs/crypto/crypto.c @@ -237,41 +237,43 @@ EXPORT_SYMBOL(fscrypt_encrypt_block_inplace); /** * fscrypt_decrypt_pagecache_blocks() - Decrypt filesystem blocks in a - * pagecache page - * @page: The locked pagecache page containing the block(s) to decrypt + * pagecache folio + * @folio: The locked pagecache folio containing the block(s) to decrypt * @len: Total size of the block(s) to decrypt. Must be a nonzero * multiple of the filesystem's block size. - * @offs: Byte offset within @page of the first block to decrypt. Must be + * @offs: Byte offset within @folio of the first block to decrypt. Must be * a multiple of the filesystem's block size. * - * The specified block(s) are decrypted in-place within the pagecache page, - * which must still be locked and not uptodate. Normally, blocksize == - * PAGE_SIZE and the whole page is decrypted at once. + * The specified block(s) are decrypted in-place within the pagecache folio, + * which must still be locked and not uptodate. * * This is for use by the filesystem's ->readahead() method. * * Return: 0 on success; -errno on failure */ -int fscrypt_decrypt_pagecache_blocks(struct page *page, unsigned int len, - unsigned int offs) +int fscrypt_decrypt_pagecache_blocks(struct folio *folio, size_t len, + size_t offs) { - const struct inode *inode = page->mapping->host; + const struct inode *inode = folio->mapping->host; const unsigned int blockbits = inode->i_blkbits; const unsigned int blocksize = 1 << blockbits; - u64 lblk_num = ((u64)page->index << (PAGE_SHIFT - blockbits)) + + u64 lblk_num = ((u64)folio->index << (PAGE_SHIFT - blockbits)) + (offs >> blockbits); - unsigned int i; + size_t i; int err; - if (WARN_ON_ONCE(!PageLocked(page))) + if (WARN_ON_ONCE(!folio_test_locked(folio))) return -EINVAL; if (WARN_ON_ONCE(len <= 0 || !IS_ALIGNED(len | offs, blocksize))) return -EINVAL; for (i = offs; i < offs + len; i += blocksize, lblk_num++) { + struct page *page = folio_page(folio, i >> PAGE_SHIFT); + err = fscrypt_crypt_block(inode, FS_DECRYPT, lblk_num, page, - page, blocksize, i, GFP_NOFS); + page, blocksize, i & ~PAGE_MASK, + GFP_NOFS); if (err) return err; } diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 9d9f414..0fe1b74 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -1136,7 +1136,8 @@ static int ext4_block_write_begin(struct page *page, loff_t pos, unsigned len, for (i = 0; i < nr_wait; i++) { int err2; - err2 = fscrypt_decrypt_pagecache_blocks(page, blocksize, + err2 = fscrypt_decrypt_pagecache_blocks(page_folio(page), + blocksize, bh_offset(wait[i])); if (err2) { clear_buffer_uptodate(wait[i]); @@ -3858,7 +3859,8 @@ static int __ext4_block_zero_page_range(handle_t *handle, if (fscrypt_inode_uses_fs_layer_crypto(inode)) { /* We expect the key to be set. */ BUG_ON(!fscrypt_has_encryption_key(inode)); - err = fscrypt_decrypt_pagecache_blocks(page, blocksize, + err = fscrypt_decrypt_pagecache_blocks(page_folio(page), + blocksize, bh_offset(bh)); if (err) { clear_buffer_uptodate(bh); diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h index 4f5f8a6..4335044 100644 --- a/include/linux/fscrypt.h +++ b/include/linux/fscrypt.h @@ -257,8 +257,8 @@ 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); -int fscrypt_decrypt_pagecache_blocks(struct page *page, unsigned int len, - unsigned int offs); +int fscrypt_decrypt_pagecache_blocks(struct folio *folio, size_t len, + size_t offs); int fscrypt_decrypt_block_inplace(const struct inode *inode, struct page *page, unsigned int len, unsigned int offs, u64 lblk_num); @@ -422,9 +422,8 @@ static inline int fscrypt_encrypt_block_inplace(const struct inode *inode, return -EOPNOTSUPP; } -static inline int fscrypt_decrypt_pagecache_blocks(struct page *page, - unsigned int len, - unsigned int offs) +static inline int fscrypt_decrypt_pagecache_blocks(struct folio *folio, + size_t len, size_t offs) { return -EOPNOTSUPP; } -- 2.7.4