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passt/siphash.c
Stefano Brivio ca2749e1bd passt: Relicense to GPL 2.0, or any later version 
In practical terms, passt doesn't benefit from the additional
protection offered by the AGPL over the GPL, because it's not
suitable to be executed over a computer network.

Further, restricting the distribution under the version 3 of the GPL
wouldn't provide any practical advantage either, as long as the passt
codebase is concerned, and might cause unnecessary compatibility
dilemmas.

Change licensing terms to the GNU General Public License Version 2,
or any later version, with written permission from all current and
past contributors, namely: myself, David Gibson, Laine Stump, Andrea
Bolognani, Paul Holzinger, Richard W.M. Jones, Chris Kuhn, Florian
Weimer, Giuseppe Scrivano, Stefan Hajnoczi, and Vasiliy Ulyanov.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
2023-04-06 18:00:33 +02:00

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// SPDX-License-Identifier: GPL-2.0-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
*/
/* Type-Based Alias Analysis (TBAA) optimisation in gcc 11 and 12 (-flto -O2)
* makes these functions essentially useless by allowing reordering of stores of
* input data across function calls. Not even declaring @in as char pointer is
* enough: disable gcc's interpretation of strict aliasing altogether. See also:
*
* https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106706
* https://stackoverflow.com/questions/2958633/gcc-strict-aliasing-and-horror-stories
* https://lore.kernel.org/all/alpine.LFD.2.00.0901121128080.6528__33422.5328093909$1232291247$gmane$org@localhost.localdomain/
*/
/* NOLINTNEXTLINE(clang-diagnostic-unknown-attributes) */
__attribute__((optimize("-fno-strict-aliasing")))
/* cppcheck-suppress unusedFunction */
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
*/
/* NOLINTNEXTLINE(clang-diagnostic-unknown-attributes) */
__attribute__((optimize("-fno-strict-aliasing"))) /* See siphash_8b() */
/* cppcheck-suppress unusedFunction */
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
*/
/* NOLINTNEXTLINE(clang-diagnostic-unknown-attributes) */
__attribute__((optimize("-fno-strict-aliasing"))) /* See siphash_8b() */
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
*/
/* NOLINTNEXTLINE(clang-diagnostic-unknown-attributes) */
__attribute__((optimize("-fno-strict-aliasing"))) /* See siphash_8b() */
/* cppcheck-suppress unusedFunction */
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
*/
/* NOLINTNEXTLINE(clang-diagnostic-unknown-attributes) */
__attribute__((optimize("-fno-strict-aliasing"))) /* See siphash_8b() */
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;
}
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