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authorDamien Miller <djm@mindrot.org>2013-10-09 10:42:32 +1100
committerDamien Miller <djm@mindrot.org>2013-10-09 10:42:32 +1100
commit9159310087a218e28940a592896808b8eb76a039 (patch)
treeaf75e932292ad9435788ed2de5bd59530a4c1167 /openbsd-compat/arc4random.c
parent67f1d557a68d6fa8966a327d7b6dee3408cf0e72 (diff)
- (djm) [openbsd-compat/arc4random.c openbsd-compat/chacha_private.h] Pull
in OpenBSD implementation of arc4random, shortly to replace the existing bsd-arc4random.c
Diffstat (limited to 'openbsd-compat/arc4random.c')
-rw-r--r--openbsd-compat/arc4random.c261
1 files changed, 261 insertions, 0 deletions
diff --git a/openbsd-compat/arc4random.c b/openbsd-compat/arc4random.c
new file mode 100644
index 00000000..356e2318
--- /dev/null
+++ b/openbsd-compat/arc4random.c
@@ -0,0 +1,261 @@
+/* $OpenBSD: arc4random.c,v 1.25 2013/10/01 18:34:57 markus Exp $ */
+
+/*
+ * Copyright (c) 1996, David Mazieres <dm@uun.org>
+ * Copyright (c) 2008, Damien Miller <djm@openbsd.org>
+ * Copyright (c) 2013, Markus Friedl <markus@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.
+ */
+
+/*
+ * ChaCha based random number generator for OpenBSD.
+ */
+
+#include <fcntl.h>
+#include <limits.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/param.h>
+#include <sys/time.h>
+#include <sys/sysctl.h>
+#include "thread_private.h"
+
+#define KEYSTREAM_ONLY
+#include "chacha_private.h"
+
+#ifdef __GNUC__
+#define inline __inline
+#else /* !__GNUC__ */
+#define inline
+#endif /* !__GNUC__ */
+
+#define KEYSZ 32
+#define IVSZ 8
+#define BLOCKSZ 64
+#define RSBUFSZ (16*BLOCKSZ)
+static int rs_initialized;
+static pid_t rs_stir_pid;
+static chacha_ctx rs; /* chacha context for random keystream */
+static u_char rs_buf[RSBUFSZ]; /* keystream blocks */
+static size_t rs_have; /* valid bytes at end of rs_buf */
+static size_t rs_count; /* bytes till reseed */
+
+static inline void _rs_rekey(u_char *dat, size_t datlen);
+
+static inline void
+_rs_init(u_char *buf, size_t n)
+{
+ if (n < KEYSZ + IVSZ)
+ return;
+ chacha_keysetup(&rs, buf, KEYSZ * 8, 0);
+ chacha_ivsetup(&rs, buf + KEYSZ);
+}
+
+static void
+_rs_stir(void)
+{
+ int mib[2];
+ size_t len;
+ u_char rnd[KEYSZ + IVSZ];
+
+ mib[0] = CTL_KERN;
+ mib[1] = KERN_ARND;
+
+ len = sizeof(rnd);
+ sysctl(mib, 2, rnd, &len, NULL, 0);
+
+ if (!rs_initialized) {
+ rs_initialized = 1;
+ _rs_init(rnd, sizeof(rnd));
+ } else
+ _rs_rekey(rnd, sizeof(rnd));
+ memset(rnd, 0, sizeof(rnd));
+
+ /* invalidate rs_buf */
+ rs_have = 0;
+ memset(rs_buf, 0, RSBUFSZ);
+
+ rs_count = 1600000;
+}
+
+static inline void
+_rs_stir_if_needed(size_t len)
+{
+ pid_t pid = getpid();
+
+ if (rs_count <= len || !rs_initialized || rs_stir_pid != pid) {
+ rs_stir_pid = pid;
+ _rs_stir();
+ } else
+ rs_count -= len;
+}
+
+static inline void
+_rs_rekey(u_char *dat, size_t datlen)
+{
+#ifndef KEYSTREAM_ONLY
+ memset(rs_buf, 0,RSBUFSZ);
+#endif
+ /* fill rs_buf with the keystream */
+ chacha_encrypt_bytes(&rs, rs_buf, rs_buf, RSBUFSZ);
+ /* mix in optional user provided data */
+ if (dat) {
+ size_t i, m;
+
+ m = MIN(datlen, KEYSZ + IVSZ);
+ for (i = 0; i < m; i++)
+ rs_buf[i] ^= dat[i];
+ }
+ /* immediately reinit for backtracking resistance */
+ _rs_init(rs_buf, KEYSZ + IVSZ);
+ memset(rs_buf, 0, KEYSZ + IVSZ);
+ rs_have = RSBUFSZ - KEYSZ - IVSZ;
+}
+
+static inline void
+_rs_random_buf(void *_buf, size_t n)
+{
+ u_char *buf = (u_char *)_buf;
+ size_t m;
+
+ _rs_stir_if_needed(n);
+ while (n > 0) {
+ if (rs_have > 0) {
+ m = MIN(n, rs_have);
+ memcpy(buf, rs_buf + RSBUFSZ - rs_have, m);
+ memset(rs_buf + RSBUFSZ - rs_have, 0, m);
+ buf += m;
+ n -= m;
+ rs_have -= m;
+ }
+ if (rs_have == 0)
+ _rs_rekey(NULL, 0);
+ }
+}
+
+static inline void
+_rs_random_u32(u_int32_t *val)
+{
+ _rs_stir_if_needed(sizeof(*val));
+ if (rs_have < sizeof(*val))
+ _rs_rekey(NULL, 0);
+ memcpy(val, rs_buf + RSBUFSZ - rs_have, sizeof(*val));
+ memset(rs_buf + RSBUFSZ - rs_have, 0, sizeof(*val));
+ rs_have -= sizeof(*val);
+ return;
+}
+
+void
+arc4random_stir(void)
+{
+ _ARC4_LOCK();
+ _rs_stir();
+ _ARC4_UNLOCK();
+}
+
+void
+arc4random_addrandom(u_char *dat, int datlen)
+{
+ int m;
+
+ _ARC4_LOCK();
+ if (!rs_initialized)
+ _rs_stir();
+ while (datlen > 0) {
+ m = MIN(datlen, KEYSZ + IVSZ);
+ _rs_rekey(dat, m);
+ dat += m;
+ datlen -= m;
+ }
+ _ARC4_UNLOCK();
+}
+
+u_int32_t
+arc4random(void)
+{
+ u_int32_t val;
+
+ _ARC4_LOCK();
+ _rs_random_u32(&val);
+ _ARC4_UNLOCK();
+ return val;
+}
+
+void
+arc4random_buf(void *buf, size_t n)
+{
+ _ARC4_LOCK();
+ _rs_random_buf(buf, n);
+ _ARC4_UNLOCK();
+}
+
+/*
+ * 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;
+
+ /* 2**32 % x == (2**32 - x) % x */
+ min = -upper_bound % upper_bound;
+
+ /*
+ * 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);
+ exit(0);
+}
+#endif