gems-kernel/source/THIRDPARTY/xnu/bsd/netinet6/ip6_id.c
2024-06-03 11:29:39 -05:00

295 lines
9.5 KiB
C

/*
* Copyright (c) 2009-2019 Apple Inc. All rights reserved.
*
* @APPLE_OSREFERENCE_LICENSE_HEADER_START@
*
* This file contains Original Code and/or Modifications of Original Code
* as defined in and that are subject to the Apple Public Source License
* Version 2.0 (the 'License'). You may not use this file except in
* compliance with the License. The rights granted to you under the License
* may not be used to create, or enable the creation or redistribution of,
* unlawful or unlicensed copies of an Apple operating system, or to
* circumvent, violate, or enable the circumvention or violation of, any
* terms of an Apple operating system software license agreement.
*
* Please obtain a copy of the License at
* http://www.opensource.apple.com/apsl/ and read it before using this file.
*
* The Original Code and all software distributed under the License are
* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
* Please see the License for the specific language governing rights and
* limitations under the License.
*
* @APPLE_OSREFERENCE_LICENSE_HEADER_END@
*/
/*-
* Copyright (C) 2003 WIDE Project.
* 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. Neither the name of the project nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE PROJECT 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 PROJECT 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.
*/
/*-
* Copyright 1998 Niels Provos <provos@citi.umich.edu>
* All rights reserved.
*
* Theo de Raadt <deraadt@openbsd.org> came up with the idea of using
* such a mathematical system to generate more random (yet non-repeating)
* ids to solve the resolver/named problem. But Niels designed the
* actual system based on the constraints.
*
* 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. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by Niels Provos.
* 4. 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 ``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 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.
*/
#include <sys/cdefs.h>
/*
* seed = random (bits - 1) bit
* n = prime, g0 = generator to n,
* j = random so that gcd(j,n-1) == 1
* g = g0^j mod n will be a generator again.
*
* X[0] = random seed.
* X[n] = a*X[n-1]+b mod m is a Linear Congruential Generator
* with a = 7^(even random) mod m,
* b = random with gcd(b,m) == 1
* m = constant and a maximal period of m-1.
*
* The transaction id is determined by:
* id[n] = seed xor (g^X[n] mod n)
*
* Effectivly the id is restricted to the lower (bits - 1) bits, thus
* yielding two different cycles by toggling the msb on and off.
* This avoids reuse issues caused by reseeding.
*/
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/param.h>
#include <sys/time.h>
#include <sys/kernel.h>
#include <sys/random.h>
#include <sys/protosw.h>
#include <libkern/libkern.h>
#include <dev/random/randomdev.h>
#include <net/if.h>
#include <net/route.h>
#include <netinet/in.h>
#include <netinet/ip6.h>
#include <netinet6/ip6_var.h>
struct randomtab {
const int ru_bits; /* resulting bits */
const long ru_out; /* Time after wich will be reseeded */
const u_int32_t ru_max; /* Uniq cycle, avoid blackjack prediction */
const u_int32_t ru_gen; /* Starting generator */
const u_int32_t ru_n; /* ru_n: prime, ru_n - 1: product of pfacts[] */
const u_int32_t ru_agen; /* determine ru_a as ru_agen^(2*rand) */
const u_int32_t ru_m; /* ru_m = 2^x*3^y */
const u_int32_t pfacts[4]; /* factors of ru_n */
u_int32_t ru_counter;
u_int32_t ru_msb;
u_int32_t ru_x;
u_int32_t ru_seed, ru_seed2;
u_int32_t ru_a, ru_b;
u_int32_t ru_g;
long ru_reseed;
};
static struct randomtab randomtab_32 = {
.ru_bits = 32, /* resulting bits */
.ru_out = 180, /* Time after wich will be reseeded */
.ru_max = 1000000000, /* Uniq cycle, avoid blackjack prediction */
.ru_gen = 2, /* Starting generator */
.ru_n = 2147483629, /* RU_N-1 = 2^2*3^2*59652323 */
.ru_agen = 7, /* determine ru_a as RU_AGEN^(2*rand) */
.ru_m = 1836660096, /* RU_M = 2^7*3^15 - don't change */
.pfacts = { 2, 3, 59652323, 0 }, /* factors of ru_n */
.ru_counter = 0,
.ru_msb = 0,
.ru_x = 0,
.ru_seed = 0,
.ru_seed2 = 0,
.ru_a = 0,
.ru_b = 0,
.ru_g = 0,
.ru_reseed = 0
};
static u_int32_t pmod(u_int32_t, u_int32_t, u_int32_t);
static void initid(struct randomtab *);
static u_int32_t randomid(struct randomtab *);
/*
* Do a fast modular exponation, returned value will be in the range
* of 0 - (mod-1)
*/
static u_int32_t
pmod(u_int32_t gen, u_int32_t expo, u_int32_t mod)
{
u_int64_t s, t, u;
s = 1;
t = gen;
u = expo;
while (u) {
if (u & 1) {
s = (s * t) % mod;
}
u >>= 1;
t = (t * t) % mod;
}
return (u_int32_t)s;
}
/*
* Initalizes the seed and chooses a suitable generator. Also toggles
* the msb flag. The msb flag is used to generate two distinct
* cycles of random numbers and thus avoiding reuse of ids.
*
* This function is called from id_randomid() when needed, an
* application does not have to worry about it.
*/
static void
initid(struct randomtab *p)
{
time_t curtime = (time_t)net_uptime();
u_int32_t j, i;
int noprime = 1;
p->ru_x = RandomULong() % p->ru_m;
/* (bits - 1) bits of random seed */
p->ru_seed = RandomULong() & (~0U >> (32 - p->ru_bits + 1));
p->ru_seed2 = RandomULong() & (~0U >> (32 - p->ru_bits + 1));
/* Determine the LCG we use */
p->ru_b = (RandomULong() & (~0U >> (32 - p->ru_bits))) | 1;
p->ru_a = pmod(p->ru_agen,
(RandomULong() & (~0U >> (32 - p->ru_bits))) & (~1U), p->ru_m);
while (p->ru_b % 3 == 0) {
p->ru_b += 2;
}
j = RandomULong() % p->ru_n;
/*
* Do a fast gcd(j, RU_N - 1), so we can find a j with
* gcd(j, RU_N - 1) == 1, giving a new generator for
* RU_GEN^j mod RU_N
*/
while (noprime) {
for (i = 0; p->pfacts[i] > 0; i++) {
if (j % p->pfacts[i] == 0) {
break;
}
}
if (p->pfacts[i] == 0) {
noprime = 0;
} else {
j = (j + 1) % p->ru_n;
}
}
p->ru_g = pmod(p->ru_gen, j, p->ru_n);
p->ru_counter = 0;
p->ru_reseed = curtime + p->ru_out;
p->ru_msb = p->ru_msb ? 0 : (1U << (p->ru_bits - 1));
}
static u_int32_t
randomid(struct randomtab *p)
{
time_t curtime = (time_t)net_uptime();
int i, n;
u_int32_t tmp;
if (p->ru_counter >= p->ru_max || curtime > p->ru_reseed) {
initid(p);
}
tmp = RandomULong();
/* Skip a random number of ids */
n = tmp & 0x3; tmp = tmp >> 2;
if (p->ru_counter + n >= p->ru_max) {
initid(p);
}
for (i = 0; i <= n; i++) {
/* Linear Congruential Generator */
p->ru_x = ((u_int64_t)p->ru_a * p->ru_x + p->ru_b) % p->ru_m;
}
p->ru_counter += i;
return (p->ru_seed ^ pmod(p->ru_g, p->ru_seed2 ^ p->ru_x, p->ru_n)) |
p->ru_msb;
}
u_int32_t
ip6_randomid(void)
{
return randomid(&randomtab_32);
}
u_int32_t
ip6_randomflowlabel(void)
{
return RandomULong() & IPV6_FLOWLABEL_MASK;
}