// SPDX-License-Identifier: GPL-2.0 OR MIT
/*
 * Copyright (C) 2015-2019 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
 *
 * This is an implementation of the BLAKE2s hash and PRF functions.
 *
 * Information: https://blake2.net/
 */

#include "blake2s.h"
#include <linux/kernel.h>

static inline u32 ror32(u32 v, int n)
{
	return (v >> n) | (v << (32 - n));
}

static inline void le32_to_cpu_array(u32 a[], size_t n)
{
	for (size_t i = 0; i < n; i++)
		a[i] = le32_to_cpu((__force __le32)a[i]);
}

static inline void cpu_to_le32_array(u32 a[], size_t n)
{
	for (size_t i = 0; i < n; i++)
		a[i] = (__force u32)cpu_to_le32(a[i]);
}

static const u8 blake2s_sigma[10][16] = {
	{ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 },
	{ 14, 10, 4, 8, 9, 15, 13, 6, 1, 12, 0, 2, 11, 7, 5, 3 },
	{ 11, 8, 12, 0, 5, 2, 15, 13, 10, 14, 3, 6, 7, 1, 9, 4 },
	{ 7, 9, 3, 1, 13, 12, 11, 14, 2, 6, 5, 10, 4, 0, 15, 8 },
	{ 9, 0, 5, 7, 2, 4, 10, 15, 14, 1, 11, 12, 6, 8, 3, 13 },
	{ 2, 12, 6, 10, 0, 11, 8, 3, 4, 13, 7, 5, 15, 14, 1, 9 },
	{ 12, 5, 1, 15, 14, 13, 4, 10, 0, 7, 6, 3, 9, 2, 8, 11 },
	{ 13, 11, 7, 14, 12, 1, 3, 9, 5, 0, 15, 4, 8, 6, 2, 10 },
	{ 6, 15, 14, 9, 11, 3, 0, 8, 12, 2, 13, 7, 1, 4, 10, 5 },
	{ 10, 2, 8, 4, 7, 6, 1, 5, 15, 11, 9, 14, 3, 12, 13, 0 },
};

static inline void blake2s_increment_counter(struct blake2s_ctx *ctx, u32 inc)
{
	ctx->t[0] += inc;
	ctx->t[1] += (ctx->t[0] < inc);
}

static void blake2s_compress(struct blake2s_ctx *ctx,
			     const u8 *data, size_t nblocks, u32 inc)
{
	u32 m[16];
	u32 v[16];
	int i;

	while (nblocks > 0) {
		blake2s_increment_counter(ctx, inc);
		memcpy(m, data, BLAKE2S_BLOCK_SIZE);
		le32_to_cpu_array(m, ARRAY_SIZE(m));
		memcpy(v, ctx->h, 32);
		v[ 8] = BLAKE2S_IV0;
		v[ 9] = BLAKE2S_IV1;
		v[10] = BLAKE2S_IV2;
		v[11] = BLAKE2S_IV3;
		v[12] = BLAKE2S_IV4 ^ ctx->t[0];
		v[13] = BLAKE2S_IV5 ^ ctx->t[1];
		v[14] = BLAKE2S_IV6 ^ ctx->f[0];
		v[15] = BLAKE2S_IV7 ^ ctx->f[1];

#define G(r, i, a, b, c, d) do { \
	a += b + m[blake2s_sigma[r][2 * i + 0]]; \
	d = ror32(d ^ a, 16); \
	c += d; \
	b = ror32(b ^ c, 12); \
	a += b + m[blake2s_sigma[r][2 * i + 1]]; \
	d = ror32(d ^ a, 8); \
	c += d; \
	b = ror32(b ^ c, 7); \
} while (0)

#define ROUND(r) do { \
	G(r, 0, v[0], v[ 4], v[ 8], v[12]); \
	G(r, 1, v[1], v[ 5], v[ 9], v[13]); \
	G(r, 2, v[2], v[ 6], v[10], v[14]); \
	G(r, 3, v[3], v[ 7], v[11], v[15]); \
	G(r, 4, v[0], v[ 5], v[10], v[15]); \
	G(r, 5, v[1], v[ 6], v[11], v[12]); \
	G(r, 6, v[2], v[ 7], v[ 8], v[13]); \
	G(r, 7, v[3], v[ 4], v[ 9], v[14]); \
} while (0)
		ROUND(0);
		ROUND(1);
		ROUND(2);
		ROUND(3);
		ROUND(4);
		ROUND(5);
		ROUND(6);
		ROUND(7);
		ROUND(8);
		ROUND(9);

#undef G
#undef ROUND

		for (i = 0; i < 8; ++i)
			ctx->h[i] ^= v[i] ^ v[i + 8];

		data += BLAKE2S_BLOCK_SIZE;
		--nblocks;
	}
}

static inline void blake2s_set_lastblock(struct blake2s_ctx *ctx)
{
	ctx->f[0] = -1;
}

void blake2s_update(struct blake2s_ctx *ctx, const u8 *in, size_t inlen)
{
	const size_t fill = BLAKE2S_BLOCK_SIZE - ctx->buflen;

	if (unlikely(!inlen))
		return;
	if (inlen > fill) {
		memcpy(ctx->buf + ctx->buflen, in, fill);
		blake2s_compress(ctx, ctx->buf, 1, BLAKE2S_BLOCK_SIZE);
		ctx->buflen = 0;
		in += fill;
		inlen -= fill;
	}
	if (inlen > BLAKE2S_BLOCK_SIZE) {
		const size_t nblocks = DIV_ROUND_UP(inlen, BLAKE2S_BLOCK_SIZE);

		blake2s_compress(ctx, in, nblocks - 1, BLAKE2S_BLOCK_SIZE);
		in += BLAKE2S_BLOCK_SIZE * (nblocks - 1);
		inlen -= BLAKE2S_BLOCK_SIZE * (nblocks - 1);
	}
	memcpy(ctx->buf + ctx->buflen, in, inlen);
	ctx->buflen += inlen;
}

void blake2s_final(struct blake2s_ctx *ctx, u8 *out)
{
	blake2s_set_lastblock(ctx);
	memset(ctx->buf + ctx->buflen, 0,
	       BLAKE2S_BLOCK_SIZE - ctx->buflen); /* Padding */
	blake2s_compress(ctx, ctx->buf, 1, ctx->buflen);
	cpu_to_le32_array(ctx->h, ARRAY_SIZE(ctx->h));
	memcpy(out, ctx->h, ctx->outlen);
	memset(ctx, 0, sizeof(*ctx));
}