From: Eric Biggers <ebigg...@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 <ebigg...@google.com>
Signed-off-by: Satya Tangirala <sat...@google.com>
---
 fs/buffer.c        |  3 +++
 fs/ext4/ext4.h     |  1 +
 fs/ext4/inode.c    |  4 ++--
 fs/ext4/page-io.c  | 11 +++++++++--
 fs/ext4/readpage.c | 15 ++++++++++++---
 fs/ext4/super.c    | 13 +++++++++++++
 6 files changed, 40 insertions(+), 7 deletions(-)

diff --git a/fs/buffer.c b/fs/buffer.c
index 86a38b979323..5d1f420de95b 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -47,6 +47,7 @@
 #include <linux/pagevec.h>
 #include <linux/sched/mm.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,
@@ -3068,6 +3069,8 @@ 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);
+
        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 b3a2cc7c0252..ce493e360814 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1148,6 +1148,7 @@ 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 516faa280ced..43a844affc57 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1237,7 +1237,7 @@ 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;
 
@@ -4034,7 +4034,7 @@ 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 12ceadef32c5..46a4aeef8275 100644
--- a/fs/ext4/page-io.c
+++ b/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;
+       }
        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;
@@ -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);
        }
@@ -474,7 +481,7 @@ 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 a30b203fa461..643f271b0b8e 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;
@@ -364,6 +367,12 @@ 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);
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index b3cbf8622eab..3415bce51a36 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
 
@@ -1461,6 +1467,7 @@ 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,
@@ -1557,6 +1564,7 @@ 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 */
@@ -1768,6 +1776,11 @@ 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}
 };
-- 
2.24.0.rc0.303.g954a862665-goog



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