+++ /dev/null
-/*
- * Copyright (c) 1996, David Mazieres <dm@uun.org>
- * Copyright (c) 2008, Damien Miller <djm@openbsd.org>
- *
- * Permission to use, copy, modify, and distribute this software for any
- * purpose with or without fee is hereby granted, provided that the above
- * copyright notice and this permission notice appear in all copies.
- *
- * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
- * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
- * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
- * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
- * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
- * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
- * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
- */
-
-/*
- * Arc4 random number generator for OpenBSD.
- *
- * This code is derived from section 17.1 of Applied Cryptography,
- * second edition, which describes a stream cipher allegedly
- * compatible with RSA Labs "RC4" cipher (the actual description of
- * which is a trade secret). The same algorithm is used as a stream
- * cipher called "arcfour" in Tatu Ylonen's ssh package.
- *
- * Here the stream cipher has been modified always to include the time
- * when initializing the state. That makes it impossible to
- * regenerate the same random sequence twice, so this can't be used
- * for encryption, but will generate good random numbers.
- *
- * RC4 is a registered trademark of RSA Laboratories.
- */
-
-#include <sys/cdefs.h>
-__FBSDID("$FreeBSD: src/lib/libc/gen/arc4random.c,v 1.25 2008/09/09 09:46:36 ache Exp $");
-
-#include "namespace.h"
-#include <sys/types.h>
-#include <sys/time.h>
-#include <stdlib.h>
-#include <fcntl.h>
-#include <unistd.h>
-#include <pthread.h>
-
-#include "libc_private.h"
-#include "un-namespace.h"
-
-struct arc4_stream {
- u_int8_t i;
- u_int8_t j;
- u_int8_t s[256];
-};
-
-static int lock = 0;
-extern void spin_lock(int*);
-extern void spin_unlock(int*);
-
-#define RANDOMDEV "/dev/random"
-#define KEYSIZE 128
-#define THREAD_LOCK() \
- do { \
- if (__isthreaded) \
- spin_lock(&lock); \
- } while (0)
-
-#define THREAD_UNLOCK() \
- do { \
- if (__isthreaded) \
- spin_unlock(&lock); \
- } while (0)
-
-static struct arc4_stream rs = {
- .i = 0,
- .j = 0,
- .s = {
- 0, 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, 225, 226, 227, 228, 229, 230, 231, 232, 233, 234, 235, 236, 237, 238, 239,
- 240, 241, 242, 243, 244, 245, 246, 247, 248, 249, 250, 251, 252, 253, 254, 255
- }
-};
-static int rs_initialized;
-static int rs_stired;
-static int arc4_count;
-
-static inline u_int8_t arc4_getbyte(void);
-static void arc4_stir(void);
-
-static struct {
- struct timeval tv;
- pid_t pid;
- u_int8_t rnd[KEYSIZE];
-} rdat;
-static volatile int rs_data_available = 0;
-
-static inline void
-arc4_addrandom(u_char *dat, int datlen)
-{
- int n;
- u_int8_t si;
-
- rs.i--;
- for (n = 0; n < 256; n++) {
- rs.i = (rs.i + 1);
- si = rs.s[rs.i];
- rs.j = (rs.j + si + dat[n % datlen]);
- rs.s[rs.i] = rs.s[rs.j];
- rs.s[rs.j] = si;
- }
- rs.j = rs.i;
-}
-
-static void
-arc4_fetch(void)
-{
- int done, fd;
- fd = _open(RANDOMDEV, O_RDONLY, 0);
- done = 0;
- if (fd >= 0) {
- if (_read(fd, &rdat, KEYSIZE) == KEYSIZE)
- done = 1;
- (void)_close(fd);
- }
- if (!done) {
- (void)gettimeofday(&rdat.tv, NULL);
- rdat.pid = getpid();
- /* We'll just take whatever was on the stack too... */
- }
-}
-
-static void
-arc4_stir(void)
-{
- int n;
- /*
- * If we don't have data, we need some now before we can integrate
- * it into the static buffers
- */
- if (!rs_data_available)
- {
- arc4_fetch();
- }
- rs_data_available = 0;
- __sync_synchronize();
-
- arc4_addrandom((u_char *)&rdat, KEYSIZE);
-
- /*
- * Throw away the first N bytes of output, as suggested in the
- * paper "Weaknesses in the Key Scheduling Algorithm of RC4"
- * by Fluher, Mantin, and Shamir. N=1024 is based on
- * suggestions in the paper "(Not So) Random Shuffles of RC4"
- * by Ilya Mironov.
- */
- for (n = 0; n < 1024; n++)
- (void) arc4_getbyte();
- arc4_count = 1600000;
- rs_stired = 1;
-}
-
-static inline u_int8_t
-arc4_getbyte(void)
-{
- u_int8_t si, sj;
-
- rs.i = (rs.i + 1);
- si = rs.s[rs.i];
- rs.j = (rs.j + si);
- sj = rs.s[rs.j];
- rs.s[rs.i] = sj;
- rs.s[rs.j] = si;
-
- return (rs.s[(si + sj) & 0xff]);
-}
-
-static inline u_int32_t
-arc4_getword(void)
-{
- u_int32_t val;
-
- val = arc4_getbyte() << 24;
- val |= arc4_getbyte() << 16;
- val |= arc4_getbyte() << 8;
- val |= arc4_getbyte();
-
- return (val);
-}
-
-/* 7944700: force restir in child */
-__private_extern__ void
-_arc4_fork_child(void)
-{
- rs_stired = 0;
- rs_data_available = 0;
-}
-
-static inline int
-arc4_check_stir(void)
-{
- if (!rs_stired || arc4_count <= 0) {
- arc4_stir();
- return 1;
- }
- return 0;
-}
-
-void
-arc4random_stir(void)
-{
- THREAD_LOCK();
- arc4_stir();
- THREAD_UNLOCK();
-}
-
-void
-arc4random_addrandom(u_char *dat, int datlen)
-{
- THREAD_LOCK();
- arc4_check_stir();
- arc4_addrandom(dat, datlen);
- THREAD_UNLOCK();
-}
-
-u_int32_t
-arc4random(void)
-{
- u_int32_t rnd;
-
- THREAD_LOCK();
-
- int did_stir = arc4_check_stir();
- rnd = arc4_getword();
- arc4_count -= 4;
-
- THREAD_UNLOCK();
- if (did_stir)
- {
- /* stirring used up our data pool, we need to read in new data outside of the lock */
- arc4_fetch();
- rs_data_available = 1;
- __sync_synchronize();
- }
-
- return (rnd);
-}
-
-void
-arc4random_buf(void *_buf, size_t n)
-{
- u_char *buf = (u_char *)_buf;
- int did_stir = 0;
-
- THREAD_LOCK();
-
- while (n--) {
- if (arc4_check_stir())
- {
- did_stir = 1;
- }
- buf[n] = arc4_getbyte();
- arc4_count--;
- }
-
- THREAD_UNLOCK();
- if (did_stir)
- {
- /* stirring used up our data pool, we need to read in new data outside of the lock */
- arc4_fetch();
- rs_data_available = 1;
- __sync_synchronize();
- }
-}
-
-/*
- * Calculate a uniformly distributed random number less than upper_bound
- * avoiding "modulo bias".
- *
- * Uniformity is achieved by generating new random numbers until the one
- * returned is outside the range [0, 2**32 % upper_bound). This
- * guarantees the selected random number will be inside
- * [2**32 % upper_bound, 2**32) which maps back to [0, upper_bound)
- * after reduction modulo upper_bound.
- */
-u_int32_t
-arc4random_uniform(u_int32_t upper_bound)
-{
- u_int32_t r, min;
-
- if (upper_bound < 2)
- return (0);
-
-#if (ULONG_MAX > 0xffffffffUL)
- min = 0x100000000UL % upper_bound;
-#else
- /* Calculate (2**32 % upper_bound) avoiding 64-bit math */
- if (upper_bound > 0x80000000)
- min = 1 + ~upper_bound; /* 2**32 - upper_bound */
- else {
- /* (2**32 - (x * 2)) % x == 2**32 % x when x <= 2**31 */
- min = ((0xffffffff - (upper_bound * 2)) + 1) % upper_bound;
- }
-#endif
-
- /*
- * This could theoretically loop forever but each retry has
- * p > 0.5 (worst case, usually far better) of selecting a
- * number inside the range we need, so it should rarely need
- * to re-roll.
- */
- for (;;) {
- r = arc4random();
- if (r >= min)
- break;
- }
-
- return (r % upper_bound);
-}
-
-#if 0
-/*-------- Test code for i386 --------*/
-#include <stdio.h>
-#include <machine/pctr.h>
-int
-main(int argc, char **argv)
-{
- const int iter = 1000000;
- int i;
- pctrval v;
-
- v = rdtsc();
- for (i = 0; i < iter; i++)
- arc4random();
- v = rdtsc() - v;
- v /= iter;
-
- printf("%qd cycles\n", v);
-}
-#endif
projects / apple / libc.git / blobdiff