Make the ARM scalar AES implementation closer to constant-time by
disabling interrupts and prefetching the tables into L1 cache. This is
feasible because due to ARM's "free" rotations, the main tables are only
1024 bytes instead of the usual 4096 used by most AES implementations.
On ARM Cortex-A7, the speed loss is only about 5%. The resulting code
is still over twice as fast as aes_ti.c. Responsiveness is potentially
a concern, but interrupts are only disabled for a single AES block.
Note that even after these changes, the implementation still isn't
necessarily guaranteed to be constant-time; see
https://cr.yp.to/antiforgery/cachetiming-20050414.pdf for a discussion
of the many difficulties involved in writing truly constant-time AES
software. But it's valuable to make such attacks more difficult.
Much of this patch is based on patches suggested by Ard Biesheuvel.
Suggested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
(cherry picked from commit 913a3aa07d16e5b302f408d497a4b829910de247
https://git.kernel.org/pub/scm/linux/kernel/git/herbert/cryptodev-2.6.git master)
Bug: 112008522
Test: As series, see Ic61c13b53facfd2173065be715a7ee5f3af8760b
Change-Id: I453a7b71c3bb0051106b37cdb71d4511fd4e388a
Signed-off-by: Eric Biggers <ebiggers@google.com>
The generic AES code exposes a 32-bit align mask, which forces all
users of the code to use temporary buffers or take other measures to
ensure the alignment requirement is adhered to, even on architectures
that don't care about alignment for software algorithms such as this
one.
So drop the align mask, and fix the code to use get_unaligned_le32()
where appropriate, which will resolve to whatever is optimal for the
architecture.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Commit 5d26a105b5 ("crypto: prefix module autoloading with "crypto-"")
changed the automatic module loading when requesting crypto algorithms
to prefix all module requests with "crypto-". This requires all crypto
modules to have a crypto specific module alias even if their file name
would otherwise match the requested crypto algorithm.
Even though commit 5d26a105b5 added those aliases for a vast amount of
modules, it was missing a few. Add the required MODULE_ALIAS_CRYPTO
annotations to those files to make them get loaded automatically, again.
This fixes, e.g., requesting 'ecb(blowfish-generic)', which used to work
with kernels v3.18 and below.
Also change MODULE_ALIAS() lines to MODULE_ALIAS_CRYPTO(). The former
won't work for crypto modules any more.
Fixes: 5d26a105b5 ("crypto: prefix module autoloading with "crypto-"")
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Mathias Krause <minipli@googlemail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This prefixes all crypto module loading with "crypto-" so we never run
the risk of exposing module auto-loading to userspace via a crypto API,
as demonstrated by Mathias Krause:
https://lkml.org/lkml/2013/3/4/70
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Tables used from assembler should be marked __visible to let
the compiler know.
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Initialization of cra_list is currently mixed, most ciphers initialize this
field and most shashes do not. Initialization however is not needed at all
since cra_list is initialized/overwritten in __crypto_register_alg() with
list_add(). Therefore perform cleanup to remove all unneeded initializations
of this field in 'crypto/'.
Signed-off-by: Jussi Kivilinna <jussi.kivilinna@mbnet.fi>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
It's undefined behaviour in C to write outside the bounds of an array.
The key expansion routine takes a shortcut of creating 8 words at a
time, but this creates 4 additional words which don't fit in the array.
As everyone is hopefully now aware, GCC is at liberty to make any
assumptions and optimisations it likes in situations where it can
detect that UB has occured, up to and including nasal demons, and
as the indices being accessed in the array are trivially calculable,
it's rash to invite gcc to do take any liberties at all.
Signed-off-by: Phil Carmody <ext-phil.2.carmody@nokia.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
The tables used by the various AES algorithms are currently
computed at run-time. This has created an init ordering problem
because some AES algorithms may be registered before the tables
have been initialised.
This patch gets around this whole thing by precomputing the tables.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
The key expansion routine could be get little more generic, become
a kernel doc entry and then get exported.
Signed-off-by: Sebastian Siewior <sebastian@breakpoint.cc>
Tested-by: Stefan Hellermann <stefan@the2masters.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This patch exports four tables and the set_key() routine. This ressources
can be shared by other AES implementations (aes-x86_64 for instance).
The decryption key has been turned around (deckey[0] is the first piece
of the key instead of deckey[keylen+20]). The encrypt/decrypt functions
are looking now identical (except they are using different tables and
key).
Signed-off-by: Sebastian Siewior <sebastian@breakpoint.cc>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This three defines are used in all AES related hardware.
Signed-off-by: Sebastian Siewior <sebastian@breakpoint.cc>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Loading the crypto algorithm by the alias instead of by module directly
has the advantage that all possible implementations of this algorithm
are loaded automatically and the crypto API can choose the best one
depending on its priority.
Additionally it ensures that the generic implementation as well as the
HW driver (if available) is loaded in case the HW driver needs the
generic version as fallback in corner cases.
Signed-off-by: Sebastian Siewior <sebastian@breakpoint.cc>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
