ANDROID: dm: add support for passing through inline crypto support
Update the device-mapper core to support exposing the inline crypto
support of the underlying device(s) through the device-mapper device.
This works by creating a "passthrough keyslot manager" for the dm
device, which declares support for the set of (crypto_mode,
data_unit_size) combos which all the underlying devices support. When a
supported combo is used, the bio cloning code handles cloning the crypto
context to the bios for all the underlying devices. When an unsupported
combo is used, the blk-crypto fallback is used as usual.
Crypto support on each underlying device is ignored unless the
corresponding dm target opts into exposing it. This is needed because
for inline crypto to semantically operate on the original bio, the data
must not be transformed by the dm target. Thus, targets like dm-linear
can expose crypto support of the underlying device, but targets like
dm-crypt can't. (dm-crypt could use inline crypto itself, though.)
When a key is evicted from the dm device, it is evicted from all
underlying devices.
Bug: 137270441
Bug: 147814592
Change-Id: If28b574f2e28268db5eb9f325d4cf8f96cb63e3f
Signed-off-by: Eric Biggers <ebiggers@google.com>
5 files changed