[PATCH v11 00/12] Inline Encryption Support

Satya Tangirala
2020-04-29T07:21:36Z

This patch series adds support for Inline Encryption to the block layer,
UFS, fscrypt, f2fs and ext4.

Note that the patches in this series for the block layer (i.e. patches 1,
2, 3, 4 and 5) can be applied independently of the subsequent patches in
this series.

Inline Encryption hardware allows software to specify an encryption context
(an encryption key, crypto algorithm, data unit num, data unit size, etc.)
along with a data transfer request to a storage device, and the inline
encryption hardware will use that context to en/decrypt the data. The
inline encryption hardware is part of the storage device, and it
conceptually sits on the data path between system memory and the storage
device. Inline Encryption hardware has become increasingly common, and we
want to support it in the kernel.

Inline Encryption hardware implementations often function around the
concept of a limited number of "keyslots", which can hold an encryption
context each. The storage device can be directed to en/decrypt any
particular request with the encryption context stored in any particular
keyslot.

Patch 1 documents the whole series.

Patch 2 introduces a Keyslot Manager to efficiently manage keyslots.
The keyslot manager also functions as the interface that blk-crypto
(introduced in Patch 3), will use to program keys into inline encryption
hardware. For more information on the Keyslot Manager, refer to
documentation found in block/keyslot-manager.c and linux/keyslot-manager.h.

Patch 3 adds the block layer changes for inline encryption support. It
introduces struct bio_crypt_ctx, and a ptr to one in struct bio, which
allows struct bio to represent an encryption context that can be passed
down the storage stack from the filesystem layer to the storage driver.

Patch 4 precludes inline encryption support in a device whenever it
supports blk-integrity, because there is currently no known hardware that
supports both features, and it is not completely straightfoward to support
both of them properly, and doing it improperly might result in leaks of
information about the plaintext.

Patch 5 introduces blk-crypto-fallback - a kernel crypto API fallback for
blk-crypto to use when inline encryption hardware isn't present. This
allows filesystems to specify encryption contexts for bios without
having to worry about whether the underlying hardware has inline
encryption support, and allows for testing without real hardware inline
encryption support. This fallback is separately configurable from
blk-crypto, and can be disabled if desired while keeping inline
encryption support. It may also be possible to remove file content
en/decryption from fscrypt and simply use blk-crypto-fallback in a future
patch. For more details on blk-crypto and the fallback, refer to
Documentation/block/inline-encryption.rst.

Patches 6-8 add support for inline encryption into the UFS driver according
to the JEDEC UFS HCI v2.1 specification. Inline encryption support for
other drivers (like eMMC) may be added in the same way - the device driver
should set up a Keyslot Manager in the device's request_queue (refer to
the UFS crypto additions in ufshcd-crypto.c and ufshcd.c for an example).

Patch 9 adds the SB_INLINECRYPT mount flag to the fs layer, which filesystems
must set to indicate that they want to use blk-crypto for en/decryption of
file contents.

Patch 10 adds support to fscrypt - to use inline encryption with fscrypt,
the filesystem must be mounted with '-o inlinecrypt' - when this option is
specified, the contents of any AES-256-XTS encrypted file will be
encrypted using blk-crypto.

Patches 11 and 12 add support to f2fs and ext4 respectively, so that we have
a complete stack that can make use of inline encryption.

The patches were tested running kvm-xfstests, by specifying the introduced
"inlinecrypt" mount option, so that en/decryption happens with the
blk-crypto fallback. The patches were also tested on a Pixel 4 with UFS
hardware that has support for inline encryption.

There have been a few patch sets addressing Inline Encryption Support in
the past. Briefly, this patch set differs from those as follows:

1) "crypto: qce: ice: Add support for Inline Crypto Engine"
is specific to certain hardware, while our patch set's Inline
Encryption support for UFS is implemented according to the JEDEC UFS
specification.

2) "scsi: ufs: UFS Host Controller crypto changes" registers inline
encryption support as a kernel crypto algorithm. Our patch views inline
encryption as being fundamentally different from a generic crypto
provider (in that inline encryption is tied to a device), and so does
not use the kernel crypto API to represent inline encryption hardware.

3) "scsi: ufs: add real time/inline crypto support to UFS HCD" requires
the device mapper to work - our patch does not.

Changes v10 => v11:
- We now allocate a new bio_crypt_ctx for each request instead of
pulling and reusing the one in the bio inserted into the request. The
bio_crypt_ctx of a bio is freed after the bio is ended.
- Make each blk_ksm_keyslot store a pointer to the blk_crypto_key
instead of a copy of the blk_crypto_key, so that each blk_crypto_key
will have its own keyslot. We also won't need to compute the siphash
for a blk_crypto_key anymore.
- Minor cleanups

Changes v9 => v10:
- Incorporate Eric's fix for allowing en/decryption to happen as usual via
fscrypt in the case that hardware doesn't support the desired crypto
configuration, but blk-crypto-fallback is disabled. (Introduce
struct blk_crypto_config and blk_crypto_config_supported for fscrypt
to call, to check that either blk-crypto-fallback is enabled or the
device supports the crypto configuration).
- Update docs
- Lots of cleanups

Changes v8 => v9:
- Don't open code bio_has_crypt_ctx into callers of blk-crypto functions.
- Lots of cleanups

Changes v7 => v8:
- Pass a struct blk_ksm_keyslot * around instead of slot numbers which
simplifies some functions and passes around arguments with better types
- Make bios with no encryption context avoid making calls into blk-crypto
by checking for the presence of bi_crypt_context before making the call
- Make blk-integrity preclude inline encryption support at probe time
- Many many cleanups

Changes v6 => v7:
- Keyslot management is now done on a per-request basis rather than a
per-bio basis.
- Storage drivers can now specify the maximum number of bytes they
can accept for the data unit number (DUN) for each crypto algorithm,
and upper layers can specify the minimum number of bytes of DUN they
want with the blk_crypto_key they send with the bio - a driver is
only considered to support a blk_crypto_key if the driver supports at
least as many DUN bytes as the upper layer wants. This is necessary
because storage drivers may not support as many bytes as the
algorithm specification dictates (for e.g. UFS only supports 8 byte
DUNs for AES-256-XTS, even though the algorithm specification
says DUNs are 16 bytes long).
- Introduce SB_INLINECRYPT to keep track of whether inline encryption
is enabled for a filesystem (instead of using an fscrypt_operation).
- Expose keyslot manager declaration and embed it within ufs_hba to
clean up code.
- Make blk-crypto preclude blk-integrity.
- Some bug fixes
- Introduce UFSHCD_QUIRK_BROKEN_CRYPTO for UFS drivers that don't
support inline encryption (yet)

Changes v5 => v6:
- Blk-crypto's kernel crypto API fallback is no longer restricted to
8-byte DUNs. It's also now separately configurable from blk-crypto, and
can be disabled entirely, while still allowing the kernel to use inline
encryption hardware. Further, struct bio_crypt_ctx takes up less space,
and no longer contains the information needed by the crypto API
fallback - the fallback allocates the required memory when necessary.
- Blk-crypto now supports all file content encryption modes supported by
fscrypt.
- Fixed bio merging logic in blk-merge.c
- Fscrypt now supports inline encryption with the direct key policy, since
blk-crypto now has support for larger DUNs.
- Keyslot manager now uses a hashtable to lookup which keyslot contains
any particular key (thanks Eric!)
- Fscrypt support for inline encryption now handles filesystems with
multiple underlying block devices (thanks Eric!)
- Numerous cleanups

Changes v4 => v5:
- The fscrypt patch has been separated into 2. The first adds support
for the IV_INO_LBLK_64 policy (which was called INLINE_CRYPT_OPTIMIZED
in past versions of this series). This policy is now purely an on disk
format, and doesn't dictate whether blk-crypto is used for file content
encryption or not. Instead, this is now decided based on the
"inlinecrypt" mount option.
- Inline crypto key eviction is now handled by blk-crypto instead of
fscrypt.
- More refactoring.

Changes v3 => v4:
- Fixed the issue with allocating crypto_skcipher in
blk_crypto_keyslot_program.
- bio_crypto_alloc_ctx is now mempool backed.
- In f2fs, a bio's bi_crypt_context is now set up when the
bio is allocated, rather than just before the bio is
submitted - this fixes bugs in certain cases, like when an
encrypted block is being moved without decryption.
- Lots of refactoring and cleanup of blk-crypto - thanks Eric!

Changes v2 => v3:
- Overhauled keyslot manager's get keyslot logic and optimized LRU.
- Block crypto en/decryption fallback now supports data unit sizes
that divide the bvec length (instead of requiring each bvec's length
to be the same as the data unit size).
- fscrypt master key is now keyed additionally by super_block and
ci_ctfm != NULL.
- all references of "hw encryption" are replaced by inline encryption.
- address various other review comments from Eric.

Changes v1 => v2:
- Block layer and UFS changes are split into 3 patches each.
- We now only have a ptr to a struct bio_crypt_ctx in struct bio, instead
of the struct itself.
- struct bio_crypt_ctx no longer has flags.
- blk-crypto now correctly handles the case when it fails to init
(because of insufficient memory), but kernel continues to boot.
- ufshcd-crypto now works on big endian cpus.
- Many cleanups.

Eric Biggers (1):
ext4: add inline encryption support

Satya Tangirala (11):
Documentation: Document the blk-crypto framework
block: Keyslot Manager for Inline Encryption
block: Inline encryption support for blk-mq
block: Make blk-integrity preclude hardware inline encryption
block: blk-crypto-fallback for Inline Encryption
scsi: ufs: UFS driver v2.1 spec crypto additions
scsi: ufs: UFS crypto API
scsi: ufs: Add inline encryption support to UFS
fs: introduce SB_INLINECRYPT
fscrypt: add inline encryption support
f2fs: add inline encryption support

Documentation/admin-guide/ext4.rst | 6 +
Documentation/block/index.rst | 1 +
Documentation/block/inline-encryption.rst | 260 +++++++++
Documentation/filesystems/f2fs.rst | 7 +-
block/Kconfig | 17 +
block/Makefile | 2 +
block/bio-integrity.c | 3 +
block/bio.c | 6 +
block/blk-core.c | 21 +-
block/blk-crypto-fallback.c | 655 ++++++++++++++++++++++
block/blk-crypto-internal.h | 201 +++++++
block/blk-crypto.c | 398 +++++++++++++
block/blk-integrity.c | 7 +
block/blk-map.c | 1 +
block/blk-merge.c | 11 +
block/blk-mq.c | 14 +
block/blk.h | 2 +
block/bounce.c | 2 +
block/keyslot-manager.c | 399 +++++++++++++
drivers/md/dm.c | 3 +
drivers/scsi/ufs/Kconfig | 9 +
drivers/scsi/ufs/Makefile | 1 +
drivers/scsi/ufs/ufshcd-crypto.c | 226 ++++++++
drivers/scsi/ufs/ufshcd-crypto.h | 60 ++
drivers/scsi/ufs/ufshcd.c | 46 +-
drivers/scsi/ufs/ufshcd.h | 24 +
drivers/scsi/ufs/ufshci.h | 67 ++-
fs/buffer.c | 7 +-
fs/crypto/Kconfig | 6 +
fs/crypto/Makefile | 1 +
fs/crypto/bio.c | 50 ++
fs/crypto/crypto.c | 2 +-
fs/crypto/fname.c | 4 +-
fs/crypto/fscrypt_private.h | 120 +++-
fs/crypto/inline_crypt.c | 365 ++++++++++++
fs/crypto/keyring.c | 4 +-
fs/crypto/keysetup.c | 92 ++-
fs/crypto/keysetup_v1.c | 16 +-
fs/ext4/inode.c | 4 +-
fs/ext4/page-io.c | 6 +-
fs/ext4/readpage.c | 11 +-
fs/ext4/super.c | 9 +
fs/f2fs/compress.c | 2 +-
fs/f2fs/data.c | 68 ++-
fs/f2fs/super.c | 32 ++
fs/proc_namespace.c | 1 +
include/linux/blk-crypto.h | 122 ++++
include/linux/blk_types.h | 6 +
include/linux/blkdev.h | 41 ++
include/linux/fs.h | 1 +
include/linux/fscrypt.h | 57 ++
include/linux/keyslot-manager.h | 106 ++++
52 files changed, 3492 insertions(+), 90 deletions(-)
create mode 100644 Documentation/block/inline-encryption.rst
create mode 100644 block/blk-crypto-fallback.c
create mode 100644 block/blk-crypto-internal.h
create mode 100644 block/blk-crypto.c
create mode 100644 block/keyslot-manager.c
create mode 100644 drivers/scsi/ufs/ufshcd-crypto.c
create mode 100644 drivers/scsi/ufs/ufshcd-crypto.h
create mode 100644 fs/crypto/inline_crypt.c
create mode 100644 include/linux/blk-crypto.h
create mode 100644 include/linux/keyslot-manager.h

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2.26.2.303.gf8c07b1a785-goog