BACKPORT: FROMLIST: ext4: add inline encryption support

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.

Bug: 137270441
Test: tested as series; see Ie1b77f7615d6a7a60fdc9105c7ab2200d17636a8
Change-Id: I73dac46ff1eba56a13975c387b20554416ddbad8
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Satya Tangirala <satyat@google.com>
Link: https://lore.kernel.org/linux-fscrypt/20191028072032.6911-10-satyat@google.com/

fs/buffer.c

@@ -46,6 +46,7 @@
 #include <linux/bit_spinlock.h>
 #include <linux/pagevec.h>
 #include <trace/events/block.h>
+#include <linux/fscrypt.h>
 
 static int fsync_buffers_list(spinlock_t *lock, struct list_head *list);
 static int submit_bh_wbc(int op, int op_flags, struct buffer_head *bh,
@@ -3125,6 +3126,8 @@ 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 | __GFP_NOFAIL);
+
 	if (wbc) {
 		wbc_init_bio(wbc, bio);
 		wbc_account_io(wbc, bh->b_page, bh->b_size);

fs/ext4/ext4.h

@@ -1155,6 +1155,7 @@ struct ext4_inode_info {
 #define EXT4_MOUNT_DIOREAD_NOLOCK	0x400000 /* Enable support for dio read nolocking */
 #define EXT4_MOUNT_JOURNAL_CHECKSUM	0x800000 /* Journal checksums */
 #define EXT4_MOUNT_JOURNAL_ASYNC_COMMIT	0x1000000 /* Journal Async Commit */
+#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 */

fs/ext4/inode.c

@@ -1232,7 +1232,7 @@ static int ext4_block_write_begin(struct page *page, loff_t pos, unsigned len,
 		    (block_start < from || block_end > to)) {
 			ll_rw_block(REQ_OP_READ, 0, 1, &bh);
 			*wait_bh++ = bh;
-			decrypt = IS_ENCRYPTED(inode) && S_ISREG(inode->i_mode);
+			decrypt = fscrypt_inode_uses_fs_layer_crypto(inode);
 		}
 	}
 	/*
@@ -4061,7 +4061,7 @@ 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));
 			BUG_ON(blocksize != PAGE_SIZE);

fs/ext4/page-io.c

@@ -362,10 +362,16 @@ static int io_submit_init_bio(struct ext4_io_submit *io,
 			      struct buffer_head *bh)
 {
 	struct bio *bio;
+	int err;
 
 	bio = bio_alloc(GFP_NOIO, BIO_MAX_PAGES);
 	if (!bio)
 		return -ENOMEM;
+	err = fscrypt_set_bio_crypt_ctx_bh(bio, bh, GFP_NOIO);
+	if (err) {
+		bio_put(bio);
+		return err;
+	}
 	wbc_init_bio(io->io_wbc, bio);
 	bio->bi_iter.bi_sector = bh->b_blocknr * (bh->b_size >> 9);
 	bio_set_dev(bio, bh->b_bdev);
@@ -383,7 +389,8 @@ static int 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);
 	}
@@ -469,7 +476,7 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
 
 	bh = head = page_buffers(page);
 
-	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;
 
 	retry_encrypt:

fs/ext4/readpage.c

@@ -198,7 +198,7 @@ static struct bio_post_read_ctx *get_bio_post_read_ctx(struct inode *inode,
 	unsigned int post_read_steps = 0;
 	struct bio_post_read_ctx *ctx = NULL;
 
-	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))
@@ -259,6 +259,7 @@ 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;
@@ -290,7 +291,8 @@ 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;
@@ -390,7 +392,8 @@ 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:
 			ext4_submit_bio_read(bio);
 			bio = NULL;
@@ -402,6 +405,12 @@ int ext4_mpage_readpages(struct address_space *mapping,
 				min_t(int, nr_pages, BIO_MAX_PAGES));
 			if (!bio)
 				goto set_error_page;
+			if (fscrypt_set_bio_crypt_ctx(bio, inode, next_block,
+						      GFP_KERNEL) != 0) {
+				bio_put(bio);
+				bio = NULL;
+				goto set_error_page;
+			}
 			ctx = get_bio_post_read_ctx(inode, bio, page->index);
 			if (IS_ERR(ctx)) {
 				bio_put(bio);

fs/ext4/super.c

@@ -1297,6 +1297,11 @@ static void ext4_get_ino_and_lblk_bits(struct super_block *sb,
 	*lblk_bits_ret = 8 * sizeof(ext4_lblk_t);
 }
 
+static bool ext4_inline_crypt_enabled(struct super_block *sb)
+{
+	return test_opt(sb, INLINECRYPT);
+}
+
 static const struct fscrypt_operations ext4_cryptops = {
 	.key_prefix		= "ext4:",
 	.get_context		= ext4_get_context,
@@ -1306,6 +1311,7 @@ static const struct fscrypt_operations ext4_cryptops = {
 	.max_namelen		= EXT4_NAME_LEN,
 	.has_stable_inodes	= ext4_has_stable_inodes,
 	.get_ino_and_lblk_bits	= ext4_get_ino_and_lblk_bits,
+	.inline_crypt_enabled	= ext4_inline_crypt_enabled,
 };
 #endif
 
@@ -1400,6 +1406,7 @@ 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,
@@ -1493,6 +1500,7 @@ 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 */
@@ -1702,6 +1710,11 @@ 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}
 };