[PATCH v6 9/9] ext4: add inline encryption support

Satya Tangirala
2019-12-18T14:52:45Z

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>
---
fs/buffer.c | 2 ++
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 | 13 +++++++++++++
6 files changed, 30 insertions(+), 7 deletions(-)

diff --git a/fs/buffer.c b/fs/buffer.c
index d8c7242426bb..3ad000db4a19 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -3108,6 +3108,8 @@ 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 f8578caba40d..aeaa01724d7c 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1153,6 +1153,7 @@ 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 28f28de0c1b6..44d9651b8638 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1090,7 +1090,7 @@ 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;

@@ -3698,7 +3698,7 @@ 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));
WARN_ON_ONCE(fscrypt_decrypt_pagecache_blocks(
diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
index 24aeedb8fc75..acde754cc5ca 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 fef7755300c3..7844e27518b4 100644
--- a/fs/ext4/readpage.c
+++ b/fs/ext4/readpage.c
@@ -183,7 +183,7 @@ 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))
@@ -220,6 +220,7 @@ 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;
@@ -252,7 +253,8 @@ 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;
@@ -352,7 +354,8 @@ 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;
@@ -366,6 +369,8 @@ 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);
ctx = get_bio_post_read_ctx(inode, bio, page->index);
if (IS_ERR(ctx)) {
bio_put(bio);
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 1d82b56d9b11..0a6b60620942 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1357,6 +1357,11 @@ 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,
@@ -1366,6 +1371,7 @@ 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

@@ -1460,6 +1466,7 @@ 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,
@@ -1556,6 +1563,7 @@ 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 */
@@ -1767,6 +1775,11 @@ 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}
};
--
2.24.1.735.g03f4e72817-goog