[PATCH v7 9/9] ext4: add inline encryption support

[Satya Tangirala <satyat@google.com>]

From: Eric Biggers <ebiggers@google.com>

Wire up ext4 to support inline encryption via the helper functions which
fs/crypto/ now provides.  This includes:

- Adding a mount option 'inlinecrypt' which enables inline encryption
  on encrypted files where it can be used.

- Setting the bio_crypt_ctx on bios that will be submitted to an
  inline-encrypted file.

  Note: submit_bh_wbc() in fs/buffer.c also needed to be patched for
  this part, since ext4 sometimes uses ll_rw_block() on file data.

- Not adding logically discontiguous data to bios that will be submitted
  to an inline-encrypted file.

- Not doing filesystem-layer crypto on inline-encrypted files.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Satya Tangirala <satyat@google.com>
---
 Documentation/admin-guide/ext4.rst |  4 ++++
 fs/buffer.c                        |  7 ++++---
 fs/ext4/ext4.h                     |  1 +
 fs/ext4/inode.c                    |  4 ++--
 fs/ext4/page-io.c                  |  6 ++++--
 fs/ext4/readpage.c                 | 11 ++++++++---
 fs/ext4/super.c                    | 19 +++++++++++++++++++
 7 files changed, 42 insertions(+), 10 deletions(-)

diff --git a/Documentation/admin-guide/ext4.rst b/Documentation/admin-guide/ext4.rst
index 9443fcef1876..b7cd3bdf827e 100644
--- a/Documentation/admin-guide/ext4.rst
+++ b/Documentation/admin-guide/ext4.rst
@@ -395,6 +395,10 @@ When mounting an ext4 filesystem, the following option are accepted:
         Documentation/filesystems/dax.txt.  Note that this option is
         incompatible with data=journal.
 
+  inlinecrypt
+        Use blk-crypto, rather than fscrypt, for file content en/decryption.
+        See Documentation/block/inline-encryption.rst.
+
 Data Mode
 =========
 There are 3 different data modes:
diff --git a/fs/buffer.c b/fs/buffer.c
index b8d28370cfd7..226f1784eda7 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -331,9 +331,8 @@ static void decrypt_bh(struct work_struct *work)
 static void end_buffer_async_read_io(struct buffer_head *bh, int uptodate)
 {
 	/* Decrypt if needed */
-	if (uptodate && IS_ENABLED(CONFIG_FS_ENCRYPTION) &&
-	    IS_ENCRYPTED(bh->b_page->mapping->host) &&
-	    S_ISREG(bh->b_page->mapping->host->i_mode)) {
+	if (uptodate &&
+	    fscrypt_inode_uses_fs_layer_crypto(bh->b_page->mapping->host)) {
 		struct decrypt_bh_ctx *ctx = kmalloc(sizeof(*ctx), GFP_ATOMIC);
 
 		if (ctx) {
@@ -3085,6 +3084,8 @@ static int submit_bh_wbc(int op, int op_flags, struct buffer_head *bh,
 	 */
 	bio = bio_alloc(GFP_NOIO, 1);
 
+	fscrypt_set_bio_crypt_ctx_bh(bio, bh, GFP_NOIO);
+
 	bio->bi_iter.bi_sector = bh->b_blocknr * (bh->b_size >> 9);
 	bio_set_dev(bio, bh->b_bdev);
 	bio->bi_write_hint = write_hint;
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 4441331d06cc..3917f4b3ec30 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1151,6 +1151,7 @@ struct ext4_inode_info {
 #define EXT4_MOUNT_JOURNAL_CHECKSUM	0x800000 /* Journal checksums */
 #define EXT4_MOUNT_JOURNAL_ASYNC_COMMIT	0x1000000 /* Journal Async Commit */
 #define EXT4_MOUNT_WARN_ON_ERROR	0x2000000 /* Trigger WARN_ON on error */
+#define EXT4_MOUNT_INLINECRYPT		0x4000000 /* Inline encryption support */
 #define EXT4_MOUNT_DELALLOC		0x8000000 /* Delalloc support */
 #define EXT4_MOUNT_DATA_ERR_ABORT	0x10000000 /* Abort on file data write */
 #define EXT4_MOUNT_BLOCK_VALIDITY	0x20000000 /* Block validity checking */
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index e60aca791d3f..9ac1dd131586 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1089,7 +1089,7 @@ 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 (IS_ENCRYPTED(inode) && S_ISREG(inode->i_mode)) {
+	} else if (fscrypt_inode_uses_fs_layer_crypto(inode)) {
 		for (i = 0; i < nr_wait; i++) {
 			int err2;
 
@@ -3720,7 +3720,7 @@ static int __ext4_block_zero_page_range(handle_t *handle,
 		/* Uhhuh. Read error. Complain and punt. */
 		if (!buffer_uptodate(bh))
 			goto unlock;
-		if (S_ISREG(inode->i_mode) && IS_ENCRYPTED(inode)) {
+		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,
diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
index 68b39e75446a..0757145a31b2 100644
--- a/fs/ext4/page-io.c
+++ b/fs/ext4/page-io.c
@@ -404,6 +404,7 @@ static void io_submit_init_bio(struct ext4_io_submit *io,
 	 * __GFP_DIRECT_RECLAIM is set, see comments for bio_alloc_bioset().
 	 */
 	bio = bio_alloc(GFP_NOIO, BIO_MAX_PAGES);
+	fscrypt_set_bio_crypt_ctx_bh(bio, bh, GFP_NOIO);
 	bio->bi_iter.bi_sector = bh->b_blocknr * (bh->b_size >> 9);
 	bio_set_dev(bio, bh->b_bdev);
 	bio->bi_end_io = ext4_end_bio;
@@ -420,7 +421,8 @@ static void io_submit_add_bh(struct ext4_io_submit *io,
 {
 	int ret;
 
-	if (io->io_bio && bh->b_blocknr != io->io_next_block) {
+	if (io->io_bio && (bh->b_blocknr != io->io_next_block ||
+			   !fscrypt_mergeable_bio_bh(io->io_bio, bh))) {
 submit_and_retry:
 		ext4_io_submit(io);
 	}
@@ -508,7 +510,7 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
 	 * (e.g. holes) to be unnecessarily encrypted, but this is rare and
 	 * can't happen in the common case of blocksize == PAGE_SIZE.
 	 */
-	if (IS_ENCRYPTED(inode) && S_ISREG(inode->i_mode) && nr_to_submit) {
+	if (fscrypt_inode_uses_fs_layer_crypto(inode) && nr_to_submit) {
 		gfp_t gfp_flags = GFP_NOFS;
 		unsigned int enc_bytes = round_up(len, i_blocksize(inode));
 
diff --git a/fs/ext4/readpage.c b/fs/ext4/readpage.c
index c1769afbf799..68eac0aeffad 100644
--- a/fs/ext4/readpage.c
+++ b/fs/ext4/readpage.c
@@ -195,7 +195,7 @@ static void ext4_set_bio_post_read_ctx(struct bio *bio,
 {
 	unsigned int post_read_steps = 0;
 
-	if (IS_ENCRYPTED(inode) && S_ISREG(inode->i_mode))
+	if (fscrypt_inode_uses_fs_layer_crypto(inode))
 		post_read_steps |= 1 << STEP_DECRYPT;
 
 	if (ext4_need_verity(inode, first_idx))
@@ -232,6 +232,7 @@ int ext4_mpage_readpages(struct address_space *mapping,
 	const unsigned blkbits = inode->i_blkbits;
 	const unsigned blocks_per_page = PAGE_SIZE >> blkbits;
 	const unsigned blocksize = 1 << blkbits;
+	sector_t next_block;
 	sector_t block_in_file;
 	sector_t last_block;
 	sector_t last_block_in_file;
@@ -264,7 +265,8 @@ int ext4_mpage_readpages(struct address_space *mapping,
 		if (page_has_buffers(page))
 			goto confused;
 
-		block_in_file = (sector_t)page->index << (PAGE_SHIFT - blkbits);
+		block_in_file = next_block =
+			(sector_t)page->index << (PAGE_SHIFT - blkbits);
 		last_block = block_in_file + nr_pages * blocks_per_page;
 		last_block_in_file = (ext4_readpage_limit(inode) +
 				      blocksize - 1) >> blkbits;
@@ -364,7 +366,8 @@ int ext4_mpage_readpages(struct address_space *mapping,
 		 * This page will go to BIO.  Do we need to send this
 		 * BIO off first?
 		 */
-		if (bio && (last_block_in_bio != blocks[0] - 1)) {
+		if (bio && (last_block_in_bio != blocks[0] - 1 ||
+			    !fscrypt_mergeable_bio(bio, inode, next_block))) {
 		submit_and_realloc:
 			submit_bio(bio);
 			bio = NULL;
@@ -376,6 +379,8 @@ int ext4_mpage_readpages(struct address_space *mapping,
 			 */
 			bio = bio_alloc(GFP_KERNEL,
 				min_t(int, nr_pages, BIO_MAX_PAGES));
+			fscrypt_set_bio_crypt_ctx(bio, inode, next_block,
+						  GFP_KERNEL);
 			ext4_set_bio_post_read_ctx(bio, inode, page->index);
 			bio_set_dev(bio, bdev);
 			bio->bi_iter.bi_sector = blocks[0] << (blkbits - 9);
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index f464dff09774..490e748b048c 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1504,6 +1504,7 @@ enum {
 	Opt_journal_path, Opt_journal_checksum, Opt_journal_async_commit,
 	Opt_abort, Opt_data_journal, Opt_data_ordered, Opt_data_writeback,
 	Opt_data_err_abort, Opt_data_err_ignore, Opt_test_dummy_encryption,
+	Opt_inlinecrypt,
 	Opt_usrjquota, Opt_grpjquota, Opt_offusrjquota, Opt_offgrpjquota,
 	Opt_jqfmt_vfsold, Opt_jqfmt_vfsv0, Opt_jqfmt_vfsv1, Opt_quota,
 	Opt_noquota, Opt_barrier, Opt_nobarrier, Opt_err,
@@ -1601,6 +1602,7 @@ static const match_table_t tokens = {
 	{Opt_noinit_itable, "noinit_itable"},
 	{Opt_max_dir_size_kb, "max_dir_size_kb=%u"},
 	{Opt_test_dummy_encryption, "test_dummy_encryption"},
+	{Opt_inlinecrypt, "inlinecrypt"},
 	{Opt_nombcache, "nombcache"},
 	{Opt_nombcache, "no_mbcache"},	/* for backward compatibility */
 	{Opt_removed, "check=none"},	/* mount option from ext2/3 */
@@ -1812,6 +1814,11 @@ static const struct mount_opts {
 	{Opt_jqfmt_vfsv1, QFMT_VFS_V1, MOPT_QFMT},
 	{Opt_max_dir_size_kb, 0, MOPT_GTE0},
 	{Opt_test_dummy_encryption, 0, MOPT_GTE0},
+#ifdef CONFIG_FS_ENCRYPTION_INLINE_CRYPT
+	{Opt_inlinecrypt, EXT4_MOUNT_INLINECRYPT, MOPT_SET},
+#else
+	{Opt_inlinecrypt, EXT4_MOUNT_INLINECRYPT, MOPT_NOSUPPORT},
+#endif
 	{Opt_nombcache, EXT4_MOUNT_NO_MBCACHE, MOPT_SET},
 	{Opt_err, 0, 0}
 };
@@ -1888,6 +1895,13 @@ static int handle_mount_opt(struct super_block *sb, char *opt, int token,
 	case Opt_nolazytime:
 		sb->s_flags &= ~SB_LAZYTIME;
 		return 1;
+	case Opt_inlinecrypt:
+#ifdef CONFIG_FS_ENCRYPTION_INLINE_CRYPT
+		sb->s_flags |= SB_INLINE_CRYPT;
+#else
+		ext4_msg(sb, KERN_ERR, "inline encryption not supported");
+#endif
+		return 1;
 	}
 
 	for (m = ext4_mount_opts; m->token != Opt_err; m++)
@@ -2300,6 +2314,8 @@ static int _ext4_show_options(struct seq_file *seq, struct super_block *sb,
 		SEQ_OPTS_PUTS("data_err=abort");
 	if (DUMMY_ENCRYPTION_ENABLED(sbi))
 		SEQ_OPTS_PUTS("test_dummy_encryption");
+	if (sb->s_flags & SB_INLINE_CRYPT)
+		SEQ_OPTS_PUTS("inlinecrypt");
 
 	ext4_show_quota_options(seq, sb);
 	return 0;
@@ -3808,6 +3824,9 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
 	 */
 	sbi->s_li_wait_mult = EXT4_DEF_LI_WAIT_MULT;
 
+	/* disable blk-crypto file content encryption by default */
+	sb->s_flags &= ~SB_INLINE_CRYPT;
+
 	blocksize = BLOCK_SIZE << le32_to_cpu(es->s_log_block_size);
 	if (blocksize < EXT4_MIN_BLOCK_SIZE ||
 	    blocksize > EXT4_MAX_BLOCK_SIZE) {
-- 
2.25.0.265.gbab2e86ba0-goog