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SubjectRe: [PATCH net-next v5 12/20] zinc: BLAKE2s generic C implementation and selftest
On Tue, Sep 18, 2018 at 06:16:38PM +0200, Jason A. Donenfeld wrote:
> The C implementation was originally based on Samuel Neves' public
> domain reference implementation but has since been heavily modified
> for the kernel. We're able to do compile-time optimizations by moving
> some scaffolding around the final function into the header file.
>
> Information: https://blake2.net/
>
> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
> Signed-off-by: Samuel Neves <sneves@dei.uc.pt>
> Cc: Andy Lutomirski <luto@kernel.org>
> Cc: Greg KH <gregkh@linuxfoundation.org>
> Cc: Jean-Philippe Aumasson <jeanphilippe.aumasson@gmail.com>
> ---
> include/zinc/blake2s.h | 95 ++
> lib/zinc/Kconfig | 3 +
> lib/zinc/Makefile | 3 +
> lib/zinc/blake2s/blake2s.c | 301 +++++
> lib/zinc/selftest/blake2s.h | 2095 +++++++++++++++++++++++++++++++++++
> 5 files changed, 2497 insertions(+)
> create mode 100644 include/zinc/blake2s.h
> create mode 100644 lib/zinc/blake2s/blake2s.c
> create mode 100644 lib/zinc/selftest/blake2s.h
>
> diff --git a/include/zinc/blake2s.h b/include/zinc/blake2s.h
> new file mode 100644
> index 000000000000..951281596274
> --- /dev/null
> +++ b/include/zinc/blake2s.h
> @@ -0,0 +1,95 @@
> +/* SPDX-License-Identifier: MIT
> + *
> + * Copyright (C) 2015-2018 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
> + */
> +
> +#ifndef _ZINC_BLAKE2S_H
> +#define _ZINC_BLAKE2S_H
> +
> +#include <linux/types.h>
> +#include <linux/kernel.h>
> +#include <crypto/algapi.h>
> +
> +enum blake2s_lengths {
> + BLAKE2S_BLOCKBYTES = 64,
> + BLAKE2S_OUTBYTES = 32,
> + BLAKE2S_KEYBYTES = 32
> +};
> +
> +struct blake2s_state {
> + u32 h[8];
> + u32 t[2];
> + u32 f[2];
> + u8 buf[BLAKE2S_BLOCKBYTES];
> + size_t buflen;
> + u8 last_node;
> +};
> +
> +void blake2s_init(struct blake2s_state *state, const size_t outlen);
> +void blake2s_init_key(struct blake2s_state *state, const size_t outlen,
> + const void *key, const size_t keylen);
> +void blake2s_update(struct blake2s_state *state, const u8 *in, size_t inlen);
> +void __blake2s_final(struct blake2s_state *state);
> +static inline void blake2s_final(struct blake2s_state *state, u8 *out,
> + const size_t outlen)
> +{
> + int i;
> +
> +#ifdef DEBUG
> + BUG_ON(!out || !outlen || outlen > BLAKE2S_OUTBYTES);
> +#endif
> + __blake2s_final(state);
> +
> + if (__builtin_constant_p(outlen) && !(outlen % sizeof(u32))) {
> + if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) ||
> + IS_ALIGNED((unsigned long)out, __alignof__(u32))) {
> + __le32 *outwords = (__le32 *)out;
> +
> + for (i = 0; i < outlen / sizeof(u32); ++i)
> + outwords[i] = cpu_to_le32(state->h[i]);
> + } else {
> + __le32 buffer[BLAKE2S_OUTBYTES];

This buffer is 4 times too long.

> +
> + for (i = 0; i < outlen / sizeof(u32); ++i)
> + buffer[i] = cpu_to_le32(state->h[i]);
> + memcpy(out, buffer, outlen);
> + memzero_explicit(buffer, sizeof(buffer));
> + }
> + } else {
> + u8 buffer[BLAKE2S_OUTBYTES] __aligned(__alignof__(u32));
> + __le32 *outwords = (__le32 *)buffer;
> +
> + for (i = 0; i < 8; ++i)
> + outwords[i] = cpu_to_le32(state->h[i]);
> + memcpy(out, buffer, outlen);
> + memzero_explicit(buffer, sizeof(buffer));
> + }
> +
> + memzero_explicit(state, sizeof(*state));
> +}

Or how about something much simpler:

static inline void blake2s_final(struct blake2s_state *state, u8 *out,
const size_t outlen)
{
#ifdef DEBUG
BUG_ON(!out || !outlen || outlen > BLAKE2S_OUTBYTES);
#endif
__blake2s_final(state);

cpu_to_le32_array(state->h, ARRAY_SIZE(state->h));
memcpy(out, state->h, outlen);

memzero_explicit(state, sizeof(*state));
}

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