aboutgitcodebugslistschat
path: root/siphash.c
blob: ec38848c0c9a0b848d9a459829cdfa9f21b7dae4 (plain) (blame)
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
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
// SPDX-License-Identifier: AGPL-3.0-or-later

/* PASST - Plug A Simple Socket Transport
 *  for qemu/UNIX domain socket mode
 *
 * PASTA - Pack A Subtle Tap Abstraction
 *  for network namespace/tap device mode
 *
 * siphash.c - SipHash routines
 *
 * Copyright (c) 2020-2021 Red Hat GmbH
 * Author: Stefano Brivio <sbrivio@redhat.com>
 *
 * This is an implementation of the SipHash-2-4-64 functions needed for TCP
 * initial sequence numbers and socket lookup table hash for IPv4 and IPv6, see:
 *
 *	Aumasson, J.P. and Bernstein, D.J., 2012, December. SipHash: a fast
 *	short-input PRF. In International Conference on Cryptology in India
 *	(pp. 489-508). Springer, Berlin, Heidelberg.
 *
 *	http://cr.yp.to/siphash/siphash-20120918.pdf
 *
 * This includes code from the reference SipHash implementation at
 * https://github.com/veorq/SipHash/ originally licensed as follows:
 *
 * --
 *  SipHash reference C implementation
 *
 * Copyright (c) 2012-2021 Jean-Philippe Aumasson
 * <jeanphilippe.aumasson@gmail.com>
 * Copyright (c) 2012-2014 Daniel J. Bernstein <djb@cr.yp.to>
 *
 * To the extent possible under law, the author(s) have dedicated all copyright
 * and related and neighboring rights to this software to the public domain
 * worldwide. This software is distributed without any warranty.
 *
 * You should have received a copy of the CC0 Public Domain Dedication along
 * with
 * this software. If not, see
 * <http://creativecommons.org/publicdomain/zero/1.0/>.
 * --
 *
 * and from the Linux kernel implementation (lib/siphash.c), originally licensed
 * as follows:
 *
 * --
 * Copyright (C) 2016 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
 *
 * This file is provided under a dual BSD/GPLv2 license.
 * --
 *
 */

#include <stdint.h>

#include "siphash.h"

#define ROTL(x, b) (uint64_t)(((x) << (b)) | ((x) >> (64 - (b))))

#define PREAMBLE(len)							  \
	uint64_t v[4] = { 0x736f6d6570736575ULL, 0x646f72616e646f6dULL,	  \
			  0x6c7967656e657261ULL, 0x7465646279746573ULL }; \
	uint64_t b = (uint64_t)(len) << 56;				  \
	uint32_t ret;							  \
	int __i;							  \
									  \
	do {								  \
		for (__i = sizeof(v) / sizeof(v[0]) - 1; __i >= 0; __i--) \
			v[__i] = k[__i % 2];				  \
	} while (0)

#define SIPROUND(n)							  \
	do {								  \
		for (__i = 0; __i < (n); __i++) {			  \
			v[0] += v[1];					  \
			v[1] = ROTL(v[1], 13) ^ v[0];			  \
			v[0] = ROTL(v[0], 32);				  \
			v[2] += v[3];					  \
			v[3] = ROTL(v[3], 16) ^ v[2];			  \
			v[0] += v[3];					  \
			v[3] = ROTL(v[3], 21) ^ v[0];			  \
			v[2] += v[1];					  \
			v[1] = ROTL(v[1], 17) ^ v[2];			  \
			v[2] = ROTL(v[2], 32);				  \
		}							  \
	} while (0)

#define POSTAMBLE							  \
	do {								  \
		v[3] ^= b;						  \
		SIPROUND(2);						  \
		v[0] ^= b;						  \
		v[2] ^= 0xff;						  \
		SIPROUND(4);						  \
		b = (v[0] ^ v[1]) ^ (v[2] ^ v[3]);			  \
		ret = (uint32_t)(b >> 32) ^ (uint32_t)b;		  \
		(void)ret;						  \
	} while (0)

/**
 * siphash_8b() - Table index or timestamp offset for TCP over IPv4 (8 bytes in)
 * @in:		Input data (remote address and two ports, or two addresses)
 * @k:		Hash function key, 128 bits
 *
 * Return: the 64-bit hash output
 */
uint64_t siphash_8b(const uint8_t *in, const uint64_t *k)
{
	PREAMBLE(8);
	v[3] ^= *(uint64_t *)in;
	SIPROUND(2);
	v[0] ^= *(uint64_t *)in;
	POSTAMBLE;

	return b;
}

/**
 * siphash_12b() - Initial sequence number for TCP over IPv4 (12 bytes in)
 * @in:		Input data (two addresses, two ports)
 * @k:		Hash function key, 128 bits
 *
 * Return: 32 bits obtained by XORing the two halves of the 64-bit hash output
 */
uint32_t siphash_12b(const uint8_t *in, const uint64_t *k)
{
	uint32_t *in32 = (uint32_t *)in;
	uint64_t combined;

	combined = (uint64_t)(*(in32 + 1)) << 32 | *in32;

	PREAMBLE(12);
	v[3] ^= combined;
	SIPROUND(2);
	v[0] ^= combined;
	b |= *(in32 + 2);
	POSTAMBLE;

	return ret;
}

/**
 * siphash_20b() - Table index for TCP over IPv6 (20 bytes in)
 * @in:		Input data (remote address, two ports)
 * @k:		Hash function key, 128 bits
 *
 * Return: the 64-bit hash output
 */
#if SIPHASH_20B_NOINLINE
__attribute__((__noinline__))	/* See comment in Makefile */
#endif
uint64_t siphash_20b(const uint8_t *in, const uint64_t *k)
{
	uint32_t *in32 = (uint32_t *)in;
	int i;

	PREAMBLE(20);

	for (i = 0; i < 2; i++, in32 += 2) {
		uint64_t combined = (uint64_t)(*(in32 + 1)) << 32 | *in32;

		v[3] ^= combined;
		SIPROUND(2);
		v[0] ^= combined;
	}

	b |= *in32;
	POSTAMBLE;

	return b;
}

/**
 * siphash_32b() - Timestamp offset for TCP over IPv6 (32 bytes in)
 * @in:		Input data (two addresses)
 * @k:		Hash function key, 128 bits
 *
 * Return: the 64-bit hash output
 */
uint32_t siphash_32b(const uint8_t *in, const uint64_t *k)
{
	uint64_t *in64 = (uint64_t *)in;
	int i;

	PREAMBLE(32);

	for (i = 0; i < 4; i++, in64++) {
		v[3] ^= *in64;
		SIPROUND(2);
		v[0] ^= *in64;
	}

	POSTAMBLE;

	return b;
}

/**
 * siphash_36b() - Initial sequence number for TCP over IPv6 (36 bytes in)
 * @in:		Input data (two addresses, two ports)
 * @k:		Hash function key, 128 bits
 *
 * Return: 32 bits obtained by XORing the two halves of the 64-bit hash output
 */
uint32_t siphash_36b(const uint8_t *in, const uint64_t *k)
{
	uint32_t *in32 = (uint32_t *)in;
	int i;

	PREAMBLE(36);

	for (i = 0; i < 4; i++, in32 += 2) {
		uint64_t combined = (uint64_t)(*(in32 + 1)) << 32 | *in32;

		v[3] ^= combined;
		SIPROUND(2);
		v[0] ^= combined;
	}

	b |= *in32;
	POSTAMBLE;

	return ret;
}