Instead of unconditionally forcing 4 byte alignment for all generic
chaining modes that rely on crypto_xor() or crypto_inc() (which may
result in unnecessary copying of data when the underlying hardware
can perform unaligned accesses efficiently), make those functions
deal with unaligned input explicitly, but only if the Kconfig symbol
HAVE_EFFICIENT_UNALIGNED_ACCESS is set. This will allow us to drop
the alignmasks from the CBC, CMAC, CTR, CTS, PCBC and SEQIV drivers.
For crypto_inc(), this simply involves making the 4-byte stride
conditional on HAVE_EFFICIENT_UNALIGNED_ACCESS being set, given that
it typically operates on 16 byte buffers.
For crypto_xor(), an algorithm is implemented that simply runs through
the input using the largest strides possible if unaligned accesses are
allowed. If they are not, an optimal sequence of memory accesses is
emitted that takes the relative alignment of the input buffers into
account, e.g., if the relative misalignment of dst and src is 4 bytes,
the entire xor operation will be completed using 4 byte loads and stores
(modulo unaligned bits at the start and end). Note that all expressions
involving misalign are simply eliminated by the compiler when
HAVE_EFFICIENT_UNALIGNED_ACCESS is defined.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This patch moves the core CBC implementation into a header file
so that it can be reused by drivers implementing CBC.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This patch converts cbc over to the skcipher interface. It also
rearranges the code to allow it to be reused by drivers.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This adds the module loading prefix "crypto-" to the template lookup
as well.
For example, attempting to load 'vfat(blowfish)' via AF_ALG now correctly
includes the "crypto-" prefix at every level, correctly rejecting "vfat":
net-pf-38
algif-hash
crypto-vfat(blowfish)
crypto-vfat(blowfish)-all
crypto-vfat
Reported-by: Mathias Krause <minipli@googlemail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Mathias Krause <minipli@googlemail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
All common block ciphers have a block size that's a power of 2. In fact,
all of our block ciphers obey this rule.
If we require this then CBC can be optimised to avoid an expensive divide
on in-place decryption.
I've also changed the saving of the first IV in the in-place decryption
case to the last IV because that lets us use walk->iv (which is already
aligned) for the xor operation where alignment is required.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This patch passes the type/mask along when constructing instances of
templates. This is in preparation for templates that may support
multiple types of instances depending on what is requested. For example,
the planned software async crypto driver will use this construct.
For the moment this allows us to check whether the instance constructed
is of the correct type and avoid returning success if the type does not
match.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This patch adds two block cipher algorithms, CBC and ECB. These
are implemented as templates on top of existing single-block cipher
algorithms. They invoke the single-block cipher through the new
encrypt_one/decrypt_one interface.
This also optimises the in-place encryption and decryption to remove
the cost of an IV copy each round.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Ard Biesheuvel