To prevent keys from being compromised if an attacker acquires read
access to kernel memory, some inline encryption hardware can accept keys
which are wrapped by a per-boot hardware-internal key. This avoids
needing to keep the raw keys in kernel memory, without limiting the
number of keys that can be used. Such hardware also supports deriving a
"software secret" for cryptographic tasks that can't be handled by
inline encryption; this is needed for fscrypt to work properly.
To support this hardware, allow struct blk_crypto_key to represent a
hardware-wrapped key as an alternative to a raw key, and make drivers
set flags in struct blk_crypto_profile to indicate which types of keys
they support. Also add the ->derive_sw_secret() low-level operation,
which drivers supporting wrapped keys must implement.
For more information, see the detailed documentation which this patch
adds to Documentation/block/inline-encryption.rst.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Tested-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org> # sm8650
Link: https://lore.kernel.org/r/20250204060041.409950-2-ebiggers@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Pull fscrypt updates from Eric Biggers:
"Some cleanups for fs/crypto/:
- Allow 256-bit master keys with AES-256-XTS
- Improve documentation and comments
- Remove unneeded field fscrypt_operations::max_namelen"
* tag 'fscrypt-for-linus' of git://git.kernel.org/pub/scm/fs/fscrypt/fscrypt:
fscrypt: improve a few comments
fscrypt: allow 256-bit master keys with AES-256-XTS
fscrypt: improve documentation for inline encryption
fscrypt: clean up comments in bio.c
fscrypt: remove fscrypt_operations::max_namelen
Currently the fscrypt inline encryption support is documented in the
"Implementation details" section, and it doesn't go into much detail.
It's really more than just an "implementation detail" though, as there
is a user-facing mount option. Also, hardware-wrapped key support (an
upcoming feature) will depend on inline encryption and will affect the
on-disk format; by definition that's not just an implementation detail.
Therefore, move this documentation into its own section and expand it.
Link: https://lore.kernel.org/r/20210916174928.65529-4-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Add a resource-managed variant of blk_ksm_init() so that drivers don't
have to worry about calling blk_ksm_destroy().
Note that the implementation uses a custom devres action to call
blk_ksm_destroy() rather than switching the two allocations to be
directly devres-managed, e.g. with devm_kmalloc(). This is because we
need to keep zeroing the memory containing the keyslots when it is
freed, and also because we want to continue using kvmalloc() (and there
is no devm_kvmalloc()).
Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Satya Tangirala <satyat@google.com>
Acked-by: Jens Axboe <axboe@kernel.dk>
Link: https://lore.kernel.org/r/20210121082155.111333-2-ebiggers@kernel.org
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
The :c:type:`foo` only works properly with structs before
Sphinx 3.x.
On Sphinx 3.x, structs should now be declared using the
.. c:struct, and referenced via :c:struct tag.
As we now have the automarkup.py macro, that automatically
convert:
struct foo
into cross-references, let's get rid of that, solving
several warnings when building docs with Sphinx 3.x.
Reviewed-by: André Almeida <andrealmeid@collabora.com> # blk-mq.rst
Reviewed-by: Takashi Iwai <tiwai@suse.de> # sound
Reviewed-by: Mike Rapoport <rppt@linux.ibm.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
The blk-crypto framework adds support for inline encryption. There are
numerous changes throughout the storage stack. This patch documents the
main design choices in the block layer, the API presented to users of
the block layer (like fscrypt or layered devices) and the API presented
to drivers for adding support for inline encryption.
Signed-off-by: Satya Tangirala <satyat@google.com>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
