[RFC PATCH 0/4] dm-default-key: target for filesystem metadata encryption

[Eric Biggers]

This series adds "metadata encryption" support to ext4 and f2fs via a
new device-mapper target dm-default-key.  dm-default-key encrypts all
data on a block device that isn't already encrypted by the filesystem.

Except for the passthrough support, dm-default-key is basically the same
as the proposed dm-inlinecrypt which omits that feature
(https://lore.kernel.org/dm-devel/20241016232748.134211-1-ebiggers@xxxxxxxxxx/).

I am sending this out for reference, as dm-default-key (which Android
has been using for a while) hasn't previously been sent to the lists in
full, and there has been interest in it.  However, my current impression
is that this feature will need to be redesigned as a filesystem native
feature in order to make it upstream.  If that is indeed the case, then
IMO it would make sense to merge dm-inlinecrypt in the mean time instead
(or add its functionality to dm-crypt) so that anyone who just wants
"dm-crypt + inline encryption hardware" gets a solution for that.

Eric Biggers (4):
  block: export blk-crypto symbols required by dm-default-key
  block: add the bi_skip_dm_default_key flag
  dm-default-key: add target for filesystem metadata encryption
  ext4,f2fs: support metadata encryption via dm-default-key

 block/bio.c                 |   3 +
 block/blk-crypto-fallback.c |   2 +
 block/blk-crypto.c          |   3 +
 drivers/md/Kconfig          |  20 ++
 drivers/md/Makefile         |   1 +
 drivers/md/dm-default-key.c | 431 ++++++++++++++++++++++++++++++++++++
 fs/crypto/inline_crypt.c    |  14 +-
 fs/f2fs/data.c              |   6 +-
 include/linux/blk-crypto.h  |  36 +++
 include/linux/blk_types.h   |   3 +
 include/linux/fscrypt.h     |  14 ++
 11 files changed, 531 insertions(+), 2 deletions(-)
 create mode 100644 drivers/md/dm-default-key.c


base-commit: c964ced7726294d40913f2127c3f185a92cb4a41
-- 
2.47.0