On the quest to remove all VLAs from the kernel[1], this avoids VLAs
by just using the maximum allocation size (4 bytes) for stack arrays.
All the VLAs in ecc were either 3 or 4 bytes (or a multiple), so just
make it 4 bytes all the time. Initialization routines are adjusted to
check that ndigits does not end up larger than the arrays.

This includes a removal of the earlier attempt at this fix from
commit a963834b4742 ("crypto/ecc: Remove stack VLA usage")

[1] https://lkml.org/lkml/2018/3/7/621Signed-off-by: NKees Cook <keescook@chromium.org>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

On the quest to remove all VLAs from the kernel[1], this switches to
a pair of kmalloc regions instead of using the stack. This also moves
the get_random_bytes() after all allocations (and drops the needless
"nbytes" variable).

[1] https://lkml.org/lkml/2018/3/7/621Signed-off-by: NKees Cook <keescook@chromium.org>
Reviewed-by: NTudor Ambarus <tudor.ambarus@microchip.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

If crypto_get_default_rng returns an error, the
function ecc_gen_privkey should return an error.
Instead, it currently tries to use the default_rng
nevertheless, thus creating a kernel panic with a
NULL pointer dereference.
Returning the error directly, as was supposedly
intended when looking at the code, fixes this.
Signed-off-by: NPierre Ducroquet <pinaraf@pinaraf.info>
Reviewed-by: NPrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

Add support for generating ecc private keys.

Generation of ecc private keys is helpful in a user-space to kernel
ecdh offload because the keys are not revealed to user-space. Private
key generation is also helpful to implement forward secrecy.

If the user provides a NULL ecc private key, the kernel will generate it
and further use it for ecdh.

Move ecdh's object files below drbg's. drbg must be present in the kernel
at the time of calling.
Signed-off-by: NTudor Ambarus <tudor.ambarus@microchip.com>
Reviewed-by: NStephan Müller <smueller@chronox.de>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

Rename ecdh_make_pub_key() to ecc_make_pub_key().
ecdh_make_pub_key() is not dh specific and the reference
to dh is wrong.
Signed-off-by: NTudor Ambarus <tudor.ambarus@microchip.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

ecc software implementation works with chunks of u64 data. There were some
unnecessary casts to u8 and then back to u64 for the ecc keys. This patch
removes the unnecessary casts.
Signed-off-by: NTudor Ambarus <tudor.ambarus@microchip.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

Signed-off-by: NTudor Ambarus <tudor.ambarus@microchip.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

There is another ecdh_shared_secret in net/bluetooth/ecc.c

Fixes: 3c4b2390 ("crypto: ecdh - Add ECDH software support")
Signed-off-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

* Implement ECDH under kpp API
 * Provide ECC software support for curve P-192 and
   P-256.
 * Add kpp test for ECDH with data generated by OpenSSL
Signed-off-by: NSalvatore Benedetto <salvatore.benedetto@intel.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>