am 7b87d441: Merge "Switch to OpenBSD res_random."
* commit '7b87d441b0f2aa3ad5021ab6bd879a995a1bc2ce': Switch to OpenBSD res_random.
This commit is contained in:
Elliott Hughes
@@ -643,7 +643,13 @@ LOCAL_SRC_FILES := \
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upstream-netbsd/lib/libc/isc/ev_timers.c \
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upstream-netbsd/lib/libc/isc/ev_timers.c \
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upstream-netbsd/lib/libc/resolv/mtctxres.c \
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upstream-netbsd/lib/libc/resolv/mtctxres.c \
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LOCAL_CFLAGS := \
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# We use the OpenBSD res_random.
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LOCAL_CFLAGS += \
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-Dres_randomid=__res_randomid
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LOCAL_SRC_FILES += \
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upstream-openbsd/lib/libc/net/res_random.c \
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LOCAL_CFLAGS += \
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$(libc_common_cflags) \
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$(libc_common_cflags) \
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-DANDROID_CHANGES \
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-DANDROID_CHANGES \
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-DINET6 \
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-DINET6 \
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@@ -616,47 +616,6 @@ net_mask(struct in_addr in) /*!< XXX - should really use system's version of thi
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}
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}
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#endif
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#endif
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#ifdef ANDROID_CHANGES
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static int
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real_randomid(u_int *random_value) {
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/* open the nonblocking random device, returning -1 on failure */
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int random_device = open("/dev/urandom", O_RDONLY | O_CLOEXEC);
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if (random_device < 0) {
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return -1;
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}
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/* read from the random device, returning -1 on failure (or too many retries)*/
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for (u_int retry = 5; retry > 0; retry--) {
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int retval = read(random_device, random_value, sizeof(u_int));
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if (retval == sizeof(u_int)) {
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*random_value &= 0xffff;
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close(random_device);
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return 0;
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} else if ((retval < 0) && (errno != EINTR)) {
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break;
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}
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}
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close(random_device);
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return -1;
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}
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#endif /* ANDROID_CHANGES */
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u_int
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res_randomid(void) {
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#ifdef ANDROID_CHANGES
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int status = 0;
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u_int output = 0;
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status = real_randomid(&output);
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if (status != -1) {
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return output;
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}
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#endif /* ANDROID_CHANGES */
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struct timeval now;
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gettimeofday(&now, NULL);
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return (0xffff & (now.tv_sec ^ now.tv_usec ^ getpid()));
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}
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/*%
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/*%
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* This routine is for closing the socket if a virtual circuit is used and
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* This routine is for closing the socket if a virtual circuit is used and
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* the program wants to close it. This provides support for endhostent()
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* the program wants to close it. This provides support for endhostent()
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275
libc/upstream-openbsd/lib/libc/net/res_random.c
Normal file
275
libc/upstream-openbsd/lib/libc/net/res_random.c
Normal file
@@ -0,0 +1,275 @@
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/* $OpenBSD: res_random.c,v 1.21 2014/07/20 04:22:34 guenther Exp $ */
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/*
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* Copyright 1997 Niels Provos <provos@physnet.uni-hamburg.de>
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* Copyright 2008 Damien Miller <djm@openbsd.org>
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* All rights reserved.
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*
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* Theo de Raadt <deraadt@openbsd.org> came up with the idea of using
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* such a mathematical system to generate more random (yet non-repeating)
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* ids to solve the resolver/named problem. But Niels designed the
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* actual system based on the constraints.
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*
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* Later modified by Damien Miller to wrap the LCG output in a 15-bit
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* permutation generator based on a Luby-Rackoff block cipher. This
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* ensures the output is non-repeating and preserves the MSB twiddle
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* trick, but makes it more resistant to LCG prediction.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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/*
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* seed = random 15bit
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* n = prime, g0 = generator to n,
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* j = random so that gcd(j,n-1) == 1
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* g = g0^j mod n will be a generator again.
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*
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* X[0] = random seed.
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* X[n] = a*X[n-1]+b mod m is a Linear Congruential Generator
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* with a = 7^(even random) mod m,
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* b = random with gcd(b,m) == 1
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* m = 31104 and a maximal period of m-1.
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*
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* The transaction id is determined by:
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* id[n] = seed xor (g^X[n] mod n)
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*
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* Effectivly the id is restricted to the lower 15 bits, thus
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* yielding two different cycles by toggling the msb on and off.
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* This avoids reuse issues caused by reseeding.
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*
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* The output of this generator is then randomly permuted though a
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* custom 15 bit Luby-Rackoff block cipher.
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*/
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#include <sys/types.h>
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#include <netinet/in.h>
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#include <sys/time.h>
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#include <resolv.h>
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#include <unistd.h>
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#include <stdlib.h>
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#include <string.h>
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#include "thread_private.h"
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#define RU_OUT 180 /* Time after wich will be reseeded */
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#define RU_MAX 30000 /* Uniq cycle, avoid blackjack prediction */
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#define RU_GEN 2 /* Starting generator */
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#define RU_N 32749 /* RU_N-1 = 2*2*3*2729 */
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#define RU_AGEN 7 /* determine ru_a as RU_AGEN^(2*rand) */
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#define RU_M 31104 /* RU_M = 2^7*3^5 - don't change */
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#define RU_ROUNDS 11 /* Number of rounds for permute (odd) */
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struct prf_ctx {
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/* PRF lookup table for odd rounds (7 bits input to 8 bits output) */
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u_char prf7[(RU_ROUNDS / 2) * (1 << 7)];
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/* PRF lookup table for even rounds (8 bits input to 7 bits output) */
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u_char prf8[((RU_ROUNDS + 1) / 2) * (1 << 8)];
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};
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#define PFAC_N 3
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static const u_int16_t pfacts[PFAC_N] = {
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2,
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3,
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2729
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};
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static u_int16_t ru_x;
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static u_int16_t ru_seed, ru_seed2;
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static u_int16_t ru_a, ru_b;
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static u_int16_t ru_g;
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static u_int16_t ru_counter = 0;
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static u_int16_t ru_msb = 0;
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static struct prf_ctx *ru_prf = NULL;
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static time_t ru_reseed;
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static u_int16_t pmod(u_int16_t, u_int16_t, u_int16_t);
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static void res_initid(void);
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/*
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* Do a fast modular exponation, returned value will be in the range
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* of 0 - (mod-1)
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*/
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static u_int16_t
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pmod(u_int16_t gen, u_int16_t exp, u_int16_t mod)
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{
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u_int16_t s, t, u;
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s = 1;
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t = gen;
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u = exp;
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while (u) {
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if (u & 1)
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s = (s * t) % mod;
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u >>= 1;
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t = (t * t) % mod;
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}
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return (s);
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}
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/*
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* 15-bit permutation based on Luby-Rackoff block cipher
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*/
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static u_int
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permute15(u_int in)
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{
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int i;
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u_int left, right, tmp;
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if (ru_prf == NULL)
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return in;
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left = (in >> 8) & 0x7f;
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right = in & 0xff;
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/*
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* Each round swaps the width of left and right. Even rounds have
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* a 7-bit left, odd rounds have an 8-bit left. Since this uses an
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* odd number of rounds, left is always 8 bits wide at the end.
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*/
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for (i = 0; i < RU_ROUNDS; i++) {
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if ((i & 1) == 0)
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tmp = ru_prf->prf8[(i << (8 - 1)) | right] & 0x7f;
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else
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tmp = ru_prf->prf7[((i - 1) << (7 - 1)) | right];
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tmp ^= left;
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left = right;
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right = tmp;
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}
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return (right << 8) | left;
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}
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/*
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* Initializes the seed and chooses a suitable generator. Also toggles
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* the msb flag. The msb flag is used to generate two distinct
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* cycles of random numbers and thus avoiding reuse of ids.
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*
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* This function is called from res_randomid() when needed, an
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* application does not have to worry about it.
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*/
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static void
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res_initid(void)
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{
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u_int16_t j, i;
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u_int32_t tmp;
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int noprime = 1;
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struct timespec ts;
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ru_x = arc4random_uniform(RU_M);
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/* 15 bits of random seed */
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tmp = arc4random();
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ru_seed = (tmp >> 16) & 0x7FFF;
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ru_seed2 = tmp & 0x7FFF;
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/* Determine the LCG we use */
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tmp = arc4random();
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ru_b = (tmp & 0xfffe) | 1;
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ru_a = pmod(RU_AGEN, (tmp >> 16) & 0xfffe, RU_M);
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while (ru_b % 3 == 0)
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ru_b += 2;
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j = arc4random_uniform(RU_N);
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/*
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* Do a fast gcd(j,RU_N-1), so we can find a j with
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* gcd(j, RU_N-1) == 1, giving a new generator for
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* RU_GEN^j mod RU_N
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*/
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while (noprime) {
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for (i = 0; i < PFAC_N; i++)
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if (j % pfacts[i] == 0)
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break;
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if (i >= PFAC_N)
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noprime = 0;
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else
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j = (j + 1) % RU_N;
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}
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ru_g = pmod(RU_GEN, j, RU_N);
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ru_counter = 0;
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/* Initialise PRF for Luby-Rackoff permutation */
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if (ru_prf == NULL)
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ru_prf = malloc(sizeof(*ru_prf));
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if (ru_prf != NULL)
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arc4random_buf(ru_prf, sizeof(*ru_prf));
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clock_gettime(CLOCK_MONOTONIC, &ts);
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ru_reseed = ts.tv_sec + RU_OUT;
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ru_msb = ru_msb == 0x8000 ? 0 : 0x8000;
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}
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u_int
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res_randomid(void)
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{
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struct timespec ts;
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u_int r;
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_THREAD_PRIVATE_MUTEX(random);
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clock_gettime(CLOCK_MONOTONIC, &ts);
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_THREAD_PRIVATE_MUTEX_LOCK(random);
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if (ru_counter >= RU_MAX || ts.tv_sec > ru_reseed)
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res_initid();
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/* Linear Congruential Generator */
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ru_x = (ru_a * ru_x + ru_b) % RU_M;
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ru_counter++;
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r = permute15(ru_seed ^ pmod(ru_g, ru_seed2 + ru_x, RU_N)) | ru_msb;
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_THREAD_PRIVATE_MUTEX_UNLOCK(random);
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return (r);
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}
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#if 0
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int
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main(int argc, char **argv)
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{
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int i, n;
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u_int16_t wert;
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res_initid();
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printf("Generator: %u\n", ru_g);
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printf("Seed: %u\n", ru_seed);
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printf("Reseed at %ld\n", ru_reseed);
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printf("Ru_X: %u\n", ru_x);
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printf("Ru_A: %u\n", ru_a);
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printf("Ru_B: %u\n", ru_b);
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n = argc > 1 ? atoi(argv[1]) : 60001;
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for (i=0;i<n;i++) {
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wert = res_randomid();
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printf("%u\n", wert);
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}
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return 0;
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}
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#endif
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Reference in New Issue
Block a user