[dm-devel] [PATCH v5 0/7] crypto: switch to crypto API for ESSIV generation
Ard Biesheuvel
ard.biesheuvel at linaro.org
Wed Jun 26 20:40:40 UTC 2019
This series creates an ESSIV template that produces a skcipher or AEAD
transform based on a tuple of the form '<skcipher>,<cipher>,<shash>'
(or '<aead>,<cipher>,<shash>' for the AEAD case). It exposes the
encapsulated sync or async skcipher/aead by passing through all operations,
while using the cipher/shash pair to transform the input IV into an ESSIV
output IV.
This matches what both users of ESSIV in the kernel do, and so it is proposed
as a replacement for those, in patches #2 and #4.
This code has been tested using the fscrypt test suggested by Eric
(generic/549), as well as the mode-test script suggested by Milan for
the dm-crypt case. I also tested the aead case in a virtual machine,
but it definitely needs some wider testing from the dm-crypt experts.
The consensus appears to be that it would be useful if the crypto API
encapsulates the handling of multiple subsequent blocks that are
encrypted using a 64-bit LE counter as IV, and makes it the duty of
the algo to increment the counter between blocks. However, this is
equally suitable for non-ESSIV transforms (or even more so), and so
this is left as a future enhancement to be applied on top.
Changes since v4:
- make the ESSIV template IV size equal the IV size of the encapsulated
cipher - defining it as 8 bytes was needlessly restrictive, and also
complicated the code for no reason
- add a missing kfree() spotted by Smatch
- add additional algo length name checks when constructing the essiv()
cipher name
- reinstate the 'essiv' IV generation implementation in dm-crypt, but
make its generation function identical to plain64le (and drop the other
methods)
- fix a bug in the arm64 CE/NEON code
- simplify the arm64 code by reusing more of the existing CBC implementation
(patch #6 is new to this series and was added for this reason)
Changes since v3:
- address various review comments from Eric on patch #1
- use Kconfig's 'imply' instead of 'select' to permit CRYPTO_ESSIV to be
enabled as a module or disabled entirely even if fscrypt is compiled in (#2)
- fix an issue in the AEAD encrypt path caused by the IV being clobbered by
the inner skcipher before the hmac was being calculated
Changes since v2:
- fixed a couple of bugs that snuck in after I'd done the bulk of my
testing
- some cosmetic tweaks to the ESSIV template skcipher setkey function
to align it with the aead one
- add a test case for essiv(cbc(aes),aes,sha256)
- add an accelerated implementation for arm64 that combines the IV
derivation and the actual en/decryption in a single asm routine
Scroll down for tcrypt speed test result comparing the essiv template
with the asm implementation. Bare cbc(aes) tests included for reference
as well. Taken on a 2GHz Cortex-A57 (AMD Seattle)
Code can be found here
https://git.kernel.org/pub/scm/linux/kernel/git/ardb/linux.git/log/?h=essiv-v5
Cc: Herbert Xu <herbert at gondor.apana.org.au>
Cc: Eric Biggers <ebiggers at google.com>
Cc: dm-devel at redhat.com
Cc: linux-fscrypt at vger.kernel.org
Cc: Gilad Ben-Yossef <gilad at benyossef.com>
Cc: Milan Broz <gmazyland at gmail.com>
Ard Biesheuvel (7):
crypto: essiv - create wrapper template for ESSIV generation
fs: crypto: invoke crypto API for ESSIV handling
md: dm-crypt: infer ESSIV block cipher from cipher string directly
md: dm-crypt: switch to ESSIV crypto API template
crypto: essiv - add test vector for essiv(cbc(aes),aes,sha256)
crypto: arm64/aes-cts-cbc - factor out CBC en/decryption of a walk
crypto: arm64/aes - implement accelerated ESSIV/CBC mode
arch/arm64/crypto/aes-glue.c | 205 +++++--
arch/arm64/crypto/aes-modes.S | 29 +-
crypto/Kconfig | 4 +
crypto/Makefile | 1 +
crypto/essiv.c | 636 ++++++++++++++++++++
crypto/tcrypt.c | 9 +
crypto/testmgr.c | 6 +
crypto/testmgr.h | 213 +++++++
drivers/md/Kconfig | 1 +
drivers/md/dm-crypt.c | 229 ++-----
fs/crypto/Kconfig | 1 +
fs/crypto/crypto.c | 5 -
fs/crypto/fscrypt_private.h | 9 -
fs/crypto/keyinfo.c | 88 +--
14 files changed, 1111 insertions(+), 325 deletions(-)
create mode 100644 crypto/essiv.c
--
2.20.1
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