1caf43b02SWarner Losh /*- 28373d51dSHajimu UMEMOTO * Copyright (C) 2003 WIDE Project. 38373d51dSHajimu UMEMOTO * All rights reserved. 48373d51dSHajimu UMEMOTO * 58373d51dSHajimu UMEMOTO * Redistribution and use in source and binary forms, with or without 68373d51dSHajimu UMEMOTO * modification, are permitted provided that the following conditions 78373d51dSHajimu UMEMOTO * are met: 88373d51dSHajimu UMEMOTO * 1. Redistributions of source code must retain the above copyright 98373d51dSHajimu UMEMOTO * notice, this list of conditions and the following disclaimer. 108373d51dSHajimu UMEMOTO * 2. Redistributions in binary form must reproduce the above copyright 118373d51dSHajimu UMEMOTO * notice, this list of conditions and the following disclaimer in the 128373d51dSHajimu UMEMOTO * documentation and/or other materials provided with the distribution. 138373d51dSHajimu UMEMOTO * 3. Neither the name of the project nor the names of its contributors 148373d51dSHajimu UMEMOTO * may be used to endorse or promote products derived from this software 158373d51dSHajimu UMEMOTO * without specific prior written permission. 168373d51dSHajimu UMEMOTO * 178373d51dSHajimu UMEMOTO * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND 188373d51dSHajimu UMEMOTO * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 198373d51dSHajimu UMEMOTO * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 208373d51dSHajimu UMEMOTO * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE 218373d51dSHajimu UMEMOTO * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 228373d51dSHajimu UMEMOTO * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 238373d51dSHajimu UMEMOTO * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 248373d51dSHajimu UMEMOTO * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 258373d51dSHajimu UMEMOTO * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 268373d51dSHajimu UMEMOTO * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 278373d51dSHajimu UMEMOTO * SUCH DAMAGE. 28b48287a3SDavid E. O'Brien * 29b48287a3SDavid E. O'Brien * $KAME: ip6_id.c,v 1.13 2003/09/16 09:11:19 itojun Exp $ 308373d51dSHajimu UMEMOTO */ 318373d51dSHajimu UMEMOTO 32caf43b02SWarner Losh /*- 338373d51dSHajimu UMEMOTO * Copyright 1998 Niels Provos <provos@citi.umich.edu> 348373d51dSHajimu UMEMOTO * All rights reserved. 358373d51dSHajimu UMEMOTO * 368373d51dSHajimu UMEMOTO * Theo de Raadt <deraadt@openbsd.org> came up with the idea of using 378373d51dSHajimu UMEMOTO * such a mathematical system to generate more random (yet non-repeating) 388373d51dSHajimu UMEMOTO * ids to solve the resolver/named problem. But Niels designed the 398373d51dSHajimu UMEMOTO * actual system based on the constraints. 408373d51dSHajimu UMEMOTO * 418373d51dSHajimu UMEMOTO * Redistribution and use in source and binary forms, with or without 428373d51dSHajimu UMEMOTO * modification, are permitted provided that the following conditions 438373d51dSHajimu UMEMOTO * are met: 448373d51dSHajimu UMEMOTO * 1. Redistributions of source code must retain the above copyright 458373d51dSHajimu UMEMOTO * notice, this list of conditions and the following disclaimer. 468373d51dSHajimu UMEMOTO * 2. Redistributions in binary form must reproduce the above copyright 478373d51dSHajimu UMEMOTO * notice, this list of conditions and the following disclaimer in the 488373d51dSHajimu UMEMOTO * documentation and/or other materials provided with the distribution. 498373d51dSHajimu UMEMOTO * 3. All advertising materials mentioning features or use of this software 508373d51dSHajimu UMEMOTO * must display the following acknowledgement: 518373d51dSHajimu UMEMOTO * This product includes software developed by Niels Provos. 528373d51dSHajimu UMEMOTO * 4. The name of the author may not be used to endorse or promote products 538373d51dSHajimu UMEMOTO * derived from this software without specific prior written permission. 548373d51dSHajimu UMEMOTO * 558373d51dSHajimu UMEMOTO * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 568373d51dSHajimu UMEMOTO * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 578373d51dSHajimu UMEMOTO * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 588373d51dSHajimu UMEMOTO * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 598373d51dSHajimu UMEMOTO * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 608373d51dSHajimu UMEMOTO * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 618373d51dSHajimu UMEMOTO * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 628373d51dSHajimu UMEMOTO * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 638373d51dSHajimu UMEMOTO * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 648373d51dSHajimu UMEMOTO * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 65b48287a3SDavid E. O'Brien * 66b48287a3SDavid E. O'Brien * $OpenBSD: ip_id.c,v 1.6 2002/03/15 18:19:52 millert Exp $ 678373d51dSHajimu UMEMOTO */ 688373d51dSHajimu UMEMOTO 69b48287a3SDavid E. O'Brien #include <sys/cdefs.h> 70b48287a3SDavid E. O'Brien __FBSDID("$FreeBSD$"); 71b48287a3SDavid E. O'Brien 728373d51dSHajimu UMEMOTO /* 738373d51dSHajimu UMEMOTO * seed = random (bits - 1) bit 748373d51dSHajimu UMEMOTO * n = prime, g0 = generator to n, 758373d51dSHajimu UMEMOTO * j = random so that gcd(j,n-1) == 1 768373d51dSHajimu UMEMOTO * g = g0^j mod n will be a generator again. 778373d51dSHajimu UMEMOTO * 788373d51dSHajimu UMEMOTO * X[0] = random seed. 798373d51dSHajimu UMEMOTO * X[n] = a*X[n-1]+b mod m is a Linear Congruential Generator 808373d51dSHajimu UMEMOTO * with a = 7^(even random) mod m, 818373d51dSHajimu UMEMOTO * b = random with gcd(b,m) == 1 828373d51dSHajimu UMEMOTO * m = constant and a maximal period of m-1. 838373d51dSHajimu UMEMOTO * 848373d51dSHajimu UMEMOTO * The transaction id is determined by: 858373d51dSHajimu UMEMOTO * id[n] = seed xor (g^X[n] mod n) 868373d51dSHajimu UMEMOTO * 878373d51dSHajimu UMEMOTO * Effectivly the id is restricted to the lower (bits - 1) bits, thus 888373d51dSHajimu UMEMOTO * yielding two different cycles by toggling the msb on and off. 898373d51dSHajimu UMEMOTO * This avoids reuse issues caused by reseeding. 908373d51dSHajimu UMEMOTO */ 918373d51dSHajimu UMEMOTO 928373d51dSHajimu UMEMOTO #include <sys/types.h> 938373d51dSHajimu UMEMOTO #include <sys/param.h> 948373d51dSHajimu UMEMOTO #include <sys/kernel.h> 958373d51dSHajimu UMEMOTO #include <sys/socket.h> 968373d51dSHajimu UMEMOTO #include <sys/libkern.h> 978373d51dSHajimu UMEMOTO 988373d51dSHajimu UMEMOTO #include <net/if.h> 998373d51dSHajimu UMEMOTO #include <net/route.h> 100*eedc7fd9SGleb Smirnoff #include <net/vnet.h> 1018373d51dSHajimu UMEMOTO #include <netinet/in.h> 1028373d51dSHajimu UMEMOTO #include <netinet/ip6.h> 1038373d51dSHajimu UMEMOTO #include <netinet6/ip6_var.h> 1048373d51dSHajimu UMEMOTO 1058373d51dSHajimu UMEMOTO #ifndef INT32_MAX 1068373d51dSHajimu UMEMOTO #define INT32_MAX 0x7fffffffU 1078373d51dSHajimu UMEMOTO #endif 1088373d51dSHajimu UMEMOTO 1098373d51dSHajimu UMEMOTO struct randomtab { 1108373d51dSHajimu UMEMOTO const int ru_bits; /* resulting bits */ 1118373d51dSHajimu UMEMOTO const long ru_out; /* Time after wich will be reseeded */ 1128373d51dSHajimu UMEMOTO const u_int32_t ru_max; /* Uniq cycle, avoid blackjack prediction */ 1138373d51dSHajimu UMEMOTO const u_int32_t ru_gen; /* Starting generator */ 1148373d51dSHajimu UMEMOTO const u_int32_t ru_n; /* ru_n: prime, ru_n - 1: product of pfacts[] */ 1158373d51dSHajimu UMEMOTO const u_int32_t ru_agen; /* determine ru_a as ru_agen^(2*rand) */ 1168373d51dSHajimu UMEMOTO const u_int32_t ru_m; /* ru_m = 2^x*3^y */ 1178373d51dSHajimu UMEMOTO const u_int32_t pfacts[4]; /* factors of ru_n */ 1188373d51dSHajimu UMEMOTO 1198373d51dSHajimu UMEMOTO u_int32_t ru_counter; 1208373d51dSHajimu UMEMOTO u_int32_t ru_msb; 1218373d51dSHajimu UMEMOTO 1228373d51dSHajimu UMEMOTO u_int32_t ru_x; 1238373d51dSHajimu UMEMOTO u_int32_t ru_seed, ru_seed2; 1248373d51dSHajimu UMEMOTO u_int32_t ru_a, ru_b; 1258373d51dSHajimu UMEMOTO u_int32_t ru_g; 1268373d51dSHajimu UMEMOTO long ru_reseed; 1278373d51dSHajimu UMEMOTO }; 1288373d51dSHajimu UMEMOTO 1298373d51dSHajimu UMEMOTO static struct randomtab randomtab_32 = { 1308373d51dSHajimu UMEMOTO 32, /* resulting bits */ 1318373d51dSHajimu UMEMOTO 180, /* Time after wich will be reseeded */ 1328373d51dSHajimu UMEMOTO 1000000000, /* Uniq cycle, avoid blackjack prediction */ 1338373d51dSHajimu UMEMOTO 2, /* Starting generator */ 1348373d51dSHajimu UMEMOTO 2147483629, /* RU_N-1 = 2^2*3^2*59652323 */ 1358373d51dSHajimu UMEMOTO 7, /* determine ru_a as RU_AGEN^(2*rand) */ 1368373d51dSHajimu UMEMOTO 1836660096, /* RU_M = 2^7*3^15 - don't change */ 1378373d51dSHajimu UMEMOTO { 2, 3, 59652323, 0 }, /* factors of ru_n */ 1388373d51dSHajimu UMEMOTO }; 1398373d51dSHajimu UMEMOTO 1405d405368SHajimu UMEMOTO static struct randomtab randomtab_20 = { 1415d405368SHajimu UMEMOTO 20, /* resulting bits */ 1425d405368SHajimu UMEMOTO 180, /* Time after wich will be reseeded */ 1435d405368SHajimu UMEMOTO 200000, /* Uniq cycle, avoid blackjack prediction */ 1445d405368SHajimu UMEMOTO 2, /* Starting generator */ 1455d405368SHajimu UMEMOTO 524269, /* RU_N-1 = 2^2*3^2*14563 */ 1465d405368SHajimu UMEMOTO 7, /* determine ru_a as RU_AGEN^(2*rand) */ 1475d405368SHajimu UMEMOTO 279936, /* RU_M = 2^7*3^7 - don't change */ 1485d405368SHajimu UMEMOTO { 2, 3, 14563, 0 }, /* factors of ru_n */ 1495d405368SHajimu UMEMOTO }; 1505d405368SHajimu UMEMOTO 1518373d51dSHajimu UMEMOTO static u_int32_t pmod(u_int32_t, u_int32_t, u_int32_t); 1528373d51dSHajimu UMEMOTO static void initid(struct randomtab *); 1538373d51dSHajimu UMEMOTO static u_int32_t randomid(struct randomtab *); 1548373d51dSHajimu UMEMOTO 1558373d51dSHajimu UMEMOTO /* 1568373d51dSHajimu UMEMOTO * Do a fast modular exponation, returned value will be in the range 1578373d51dSHajimu UMEMOTO * of 0 - (mod-1) 1588373d51dSHajimu UMEMOTO */ 1598373d51dSHajimu UMEMOTO static u_int32_t 1608373d51dSHajimu UMEMOTO pmod(u_int32_t gen, u_int32_t expo, u_int32_t mod) 1618373d51dSHajimu UMEMOTO { 1628373d51dSHajimu UMEMOTO u_int64_t s, t, u; 1638373d51dSHajimu UMEMOTO 1648373d51dSHajimu UMEMOTO s = 1; 1658373d51dSHajimu UMEMOTO t = gen; 1668373d51dSHajimu UMEMOTO u = expo; 1678373d51dSHajimu UMEMOTO 1688373d51dSHajimu UMEMOTO while (u) { 1698373d51dSHajimu UMEMOTO if (u & 1) 1708373d51dSHajimu UMEMOTO s = (s * t) % mod; 1718373d51dSHajimu UMEMOTO u >>= 1; 1728373d51dSHajimu UMEMOTO t = (t * t) % mod; 1738373d51dSHajimu UMEMOTO } 1748373d51dSHajimu UMEMOTO return (s); 1758373d51dSHajimu UMEMOTO } 1768373d51dSHajimu UMEMOTO 1778373d51dSHajimu UMEMOTO /* 1788373d51dSHajimu UMEMOTO * Initalizes the seed and chooses a suitable generator. Also toggles 1798373d51dSHajimu UMEMOTO * the msb flag. The msb flag is used to generate two distinct 1808373d51dSHajimu UMEMOTO * cycles of random numbers and thus avoiding reuse of ids. 1818373d51dSHajimu UMEMOTO * 1828373d51dSHajimu UMEMOTO * This function is called from id_randomid() when needed, an 1838373d51dSHajimu UMEMOTO * application does not have to worry about it. 1848373d51dSHajimu UMEMOTO */ 1858373d51dSHajimu UMEMOTO static void 1868373d51dSHajimu UMEMOTO initid(struct randomtab *p) 1878373d51dSHajimu UMEMOTO { 1888373d51dSHajimu UMEMOTO u_int32_t j, i; 1898373d51dSHajimu UMEMOTO int noprime = 1; 1908373d51dSHajimu UMEMOTO 1918373d51dSHajimu UMEMOTO p->ru_x = arc4random() % p->ru_m; 1928373d51dSHajimu UMEMOTO 1938373d51dSHajimu UMEMOTO /* (bits - 1) bits of random seed */ 1948373d51dSHajimu UMEMOTO p->ru_seed = arc4random() & (~0U >> (32 - p->ru_bits + 1)); 1958373d51dSHajimu UMEMOTO p->ru_seed2 = arc4random() & (~0U >> (32 - p->ru_bits + 1)); 1968373d51dSHajimu UMEMOTO 1978373d51dSHajimu UMEMOTO /* Determine the LCG we use */ 1988373d51dSHajimu UMEMOTO p->ru_b = (arc4random() & (~0U >> (32 - p->ru_bits))) | 1; 1998373d51dSHajimu UMEMOTO p->ru_a = pmod(p->ru_agen, 2008373d51dSHajimu UMEMOTO (arc4random() & (~0U >> (32 - p->ru_bits))) & (~1U), p->ru_m); 2018373d51dSHajimu UMEMOTO while (p->ru_b % 3 == 0) 2028373d51dSHajimu UMEMOTO p->ru_b += 2; 2038373d51dSHajimu UMEMOTO 2048373d51dSHajimu UMEMOTO j = arc4random() % p->ru_n; 2058373d51dSHajimu UMEMOTO 2068373d51dSHajimu UMEMOTO /* 2078373d51dSHajimu UMEMOTO * Do a fast gcd(j, RU_N - 1), so we can find a j with 2088373d51dSHajimu UMEMOTO * gcd(j, RU_N - 1) == 1, giving a new generator for 2098373d51dSHajimu UMEMOTO * RU_GEN^j mod RU_N 2108373d51dSHajimu UMEMOTO */ 2118373d51dSHajimu UMEMOTO while (noprime) { 2128373d51dSHajimu UMEMOTO for (i = 0; p->pfacts[i] > 0; i++) 2138373d51dSHajimu UMEMOTO if (j % p->pfacts[i] == 0) 2148373d51dSHajimu UMEMOTO break; 2158373d51dSHajimu UMEMOTO 2168373d51dSHajimu UMEMOTO if (p->pfacts[i] == 0) 2178373d51dSHajimu UMEMOTO noprime = 0; 2188373d51dSHajimu UMEMOTO else 2198373d51dSHajimu UMEMOTO j = (j + 1) % p->ru_n; 2208373d51dSHajimu UMEMOTO } 2218373d51dSHajimu UMEMOTO 2228373d51dSHajimu UMEMOTO p->ru_g = pmod(p->ru_gen, j, p->ru_n); 2238373d51dSHajimu UMEMOTO p->ru_counter = 0; 2248373d51dSHajimu UMEMOTO 2257d26db17SHiroki Sato p->ru_reseed = time_uptime + p->ru_out; 2268373d51dSHajimu UMEMOTO p->ru_msb = p->ru_msb ? 0 : (1U << (p->ru_bits - 1)); 2278373d51dSHajimu UMEMOTO } 2288373d51dSHajimu UMEMOTO 2298373d51dSHajimu UMEMOTO static u_int32_t 2308373d51dSHajimu UMEMOTO randomid(struct randomtab *p) 2318373d51dSHajimu UMEMOTO { 2328373d51dSHajimu UMEMOTO int i, n; 2338373d51dSHajimu UMEMOTO u_int32_t tmp; 2348373d51dSHajimu UMEMOTO 2357d26db17SHiroki Sato if (p->ru_counter >= p->ru_max || time_uptime > p->ru_reseed) 2368373d51dSHajimu UMEMOTO initid(p); 2378373d51dSHajimu UMEMOTO 2388373d51dSHajimu UMEMOTO tmp = arc4random(); 2398373d51dSHajimu UMEMOTO 2408373d51dSHajimu UMEMOTO /* Skip a random number of ids */ 2418373d51dSHajimu UMEMOTO n = tmp & 0x3; tmp = tmp >> 2; 2428373d51dSHajimu UMEMOTO if (p->ru_counter + n >= p->ru_max) 2438373d51dSHajimu UMEMOTO initid(p); 2448373d51dSHajimu UMEMOTO 2458373d51dSHajimu UMEMOTO for (i = 0; i <= n; i++) { 2468373d51dSHajimu UMEMOTO /* Linear Congruential Generator */ 2478373d51dSHajimu UMEMOTO p->ru_x = (u_int32_t)((u_int64_t)p->ru_a * p->ru_x + p->ru_b) % p->ru_m; 2488373d51dSHajimu UMEMOTO } 2498373d51dSHajimu UMEMOTO 2508373d51dSHajimu UMEMOTO p->ru_counter += i; 2518373d51dSHajimu UMEMOTO 2528373d51dSHajimu UMEMOTO return (p->ru_seed ^ pmod(p->ru_g, p->ru_seed2 ^ p->ru_x, p->ru_n)) | 2538373d51dSHajimu UMEMOTO p->ru_msb; 2548373d51dSHajimu UMEMOTO } 2558373d51dSHajimu UMEMOTO 2568373d51dSHajimu UMEMOTO u_int32_t 2578373d51dSHajimu UMEMOTO ip6_randomid(void) 2588373d51dSHajimu UMEMOTO { 2598373d51dSHajimu UMEMOTO 2608373d51dSHajimu UMEMOTO return randomid(&randomtab_32); 2618373d51dSHajimu UMEMOTO } 262672467ebSHajimu UMEMOTO 263b79274baSHajimu UMEMOTO u_int32_t 264b79274baSHajimu UMEMOTO ip6_randomflowlabel(void) 265b79274baSHajimu UMEMOTO { 266b79274baSHajimu UMEMOTO 267b79274baSHajimu UMEMOTO return randomid(&randomtab_20) & 0xfffff; 268b79274baSHajimu UMEMOTO } 269