summaryrefslogtreecommitdiffstats
path: root/fs/bcachefs/siphash.c
blob: dc1a27cc31cd4de56cdc2e44026e4be7b789c34f (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
// SPDX-License-Identifier: BSD-3-Clause
/*	$OpenBSD: siphash.c,v 1.3 2015/02/20 11:51:03 tedu Exp $ */

/*-
 * Copyright (c) 2013 Andre Oppermann <andre@FreeBSD.org>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote
 *    products derived from this software without specific prior written
 *    permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * SipHash is a family of PRFs SipHash-c-d where the integer parameters c and d
 * are the number of compression rounds and the number of finalization rounds.
 * A compression round is identical to a finalization round and this round
 * function is called SipRound.  Given a 128-bit key k and a (possibly empty)
 * byte string m, SipHash-c-d returns a 64-bit value SipHash-c-d(k; m).
 *
 * Implemented from the paper "SipHash: a fast short-input PRF", 2012.09.18,
 * by Jean-Philippe Aumasson and Daniel J. Bernstein,
 * Permanent Document ID b9a943a805fbfc6fde808af9fc0ecdfa
 * https://131002.net/siphash/siphash.pdf
 * https://131002.net/siphash/
 */

#include <asm/byteorder.h>
#include <asm/unaligned.h>
#include <linux/bitops.h>
#include <linux/string.h>

#include "siphash.h"

static void SipHash_Rounds(SIPHASH_CTX *ctx, int rounds)
{
	while (rounds--) {
		ctx->v[0] += ctx->v[1];
		ctx->v[2] += ctx->v[3];
		ctx->v[1] = rol64(ctx->v[1], 13);
		ctx->v[3] = rol64(ctx->v[3], 16);

		ctx->v[1] ^= ctx->v[0];
		ctx->v[3] ^= ctx->v[2];
		ctx->v[0] = rol64(ctx->v[0], 32);

		ctx->v[2] += ctx->v[1];
		ctx->v[0] += ctx->v[3];
		ctx->v[1] = rol64(ctx->v[1], 17);
		ctx->v[3] = rol64(ctx->v[3], 21);

		ctx->v[1] ^= ctx->v[2];
		ctx->v[3] ^= ctx->v[0];
		ctx->v[2] = rol64(ctx->v[2], 32);
	}
}

static void SipHash_CRounds(SIPHASH_CTX *ctx, const void *ptr, int rounds)
{
	u64 m = get_unaligned_le64(ptr);

	ctx->v[3] ^= m;
	SipHash_Rounds(ctx, rounds);
	ctx->v[0] ^= m;
}

void SipHash_Init(SIPHASH_CTX *ctx, const SIPHASH_KEY *key)
{
	u64 k0, k1;

	k0 = le64_to_cpu(key->k0);
	k1 = le64_to_cpu(key->k1);

	ctx->v[0] = 0x736f6d6570736575ULL ^ k0;
	ctx->v[1] = 0x646f72616e646f6dULL ^ k1;
	ctx->v[2] = 0x6c7967656e657261ULL ^ k0;
	ctx->v[3] = 0x7465646279746573ULL ^ k1;

	memset(ctx->buf, 0, sizeof(ctx->buf));
	ctx->bytes = 0;
}

void SipHash_Update(SIPHASH_CTX *ctx, int rc, int rf,
		    const void *src, size_t len)
{
	const u8 *ptr = src;
	size_t left, used;

	if (len == 0)
		return;

	used = ctx->bytes % sizeof(ctx->buf);
	ctx->bytes += len;

	if (used > 0) {
		left = sizeof(ctx->buf) - used;

		if (len >= left) {
			memcpy(&ctx->buf[used], ptr, left);
			SipHash_CRounds(ctx, ctx->buf, rc);
			len -= left;
			ptr += left;
		} else {
			memcpy(&ctx->buf[used], ptr, len);
			return;
		}
	}

	while (len >= sizeof(ctx->buf)) {
		SipHash_CRounds(ctx, ptr, rc);
		len -= sizeof(ctx->buf);
		ptr += sizeof(ctx->buf);
	}

	if (len > 0)
		memcpy(&ctx->buf[used], ptr, len);
}

void SipHash_Final(void *dst, SIPHASH_CTX *ctx, int rc, int rf)
{
	u64 r;

	r = SipHash_End(ctx, rc, rf);

	*((__le64 *) dst) = cpu_to_le64(r);
}

u64 SipHash_End(SIPHASH_CTX *ctx, int rc, int rf)
{
	u64 r;
	size_t left, used;

	used = ctx->bytes % sizeof(ctx->buf);
	left = sizeof(ctx->buf) - used;
	memset(&ctx->buf[used], 0, left - 1);
	ctx->buf[7] = ctx->bytes;

	SipHash_CRounds(ctx, ctx->buf, rc);
	ctx->v[2] ^= 0xff;
	SipHash_Rounds(ctx, rf);

	r = (ctx->v[0] ^ ctx->v[1]) ^ (ctx->v[2] ^ ctx->v[3]);
	memset(ctx, 0, sizeof(*ctx));
	return r;
}

u64 SipHash(const SIPHASH_KEY *key, int rc, int rf, const void *src, size_t len)
{
	SIPHASH_CTX ctx;

	SipHash_Init(&ctx, key);
	SipHash_Update(&ctx, rc, rf, src, len);
	return SipHash_End(&ctx, rc, rf);
}