summaryrefslogtreecommitdiffstats
path: root/ext/arc4random/arc4random.c
diff options
context:
space:
mode:
Diffstat (limited to 'ext/arc4random/arc4random.c')
-rw-r--r--ext/arc4random/arc4random.c256
1 files changed, 256 insertions, 0 deletions
diff --git a/ext/arc4random/arc4random.c b/ext/arc4random/arc4random.c
new file mode 100644
index 0000000..56ebd81
--- /dev/null
+++ b/ext/arc4random/arc4random.c
@@ -0,0 +1,256 @@
+/* $OpenBSD: arc4random.c,v 1.58 2022/07/31 13:41:45 tb 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>
+ * Copyright (c) 2014, Theo de Raadt <deraadt@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.
+ */
+
+/* OPENBSD ORIGINAL: lib/libc/crypt/arc4random.c */
+
+#include "includes.h"
+
+#include <sys/types.h>
+
+#include <fcntl.h>
+#include <limits.h>
+#include <signal.h>
+#ifdef HAVE_STDINT_H
+#include <stdint.h>
+#endif
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/time.h>
+
+#ifndef HAVE_ARC4RANDOM
+
+/*
+ * Always use the getentropy implementation from bsd-getentropy.c, which
+ * will call a native getentropy if available then fall back as required.
+ * We use a different name so that OpenSSL cannot call the wrong getentropy.
+ */
+#ifdef getentropy
+# undef getentropy
+#endif
+#define getentropy(x, y) (_ssh_compat_getentropy((x), (y)))
+
+#include "log.h"
+
+#define KEYSTREAM_ONLY
+#include "chacha_private.h"
+
+#define minimum(a, b) ((a) < (b) ? (a) : (b))
+
+#if defined(__GNUC__) || defined(_MSC_VER)
+#define inline __inline
+#else /* __GNUC__ || _MSC_VER */
+#define inline
+#endif /* !__GNUC__ && !_MSC_VER */
+
+#define KEYSZ 32
+#define IVSZ 8
+#define BLOCKSZ 64
+#define RSBUFSZ (16*BLOCKSZ)
+
+#define REKEY_BASE (1024*1024) /* NB. should be a power of 2 */
+
+/* Marked MAP_INHERIT_ZERO, so zero'd out in fork children. */
+static struct _rs {
+ size_t rs_have; /* valid bytes at end of rs_buf */
+ size_t rs_count; /* bytes till reseed */
+} *rs;
+
+/* Maybe be preserved in fork children, if _rs_allocate() decides. */
+static struct _rsx {
+ chacha_ctx rs_chacha; /* chacha context for random keystream */
+ u_char rs_buf[RSBUFSZ]; /* keystream blocks */
+} *rsx;
+
+static inline int _rs_allocate(struct _rs **, struct _rsx **);
+static inline void _rs_forkdetect(void);
+#include "arc4random.h"
+
+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;
+
+ if (rs == NULL) {
+ if (_rs_allocate(&rs, &rsx) == -1)
+ _exit(1);
+ }
+
+ chacha_keysetup(&rsx->rs_chacha, buf, KEYSZ * 8);
+ chacha_ivsetup(&rsx->rs_chacha, buf + KEYSZ);
+}
+
+static void
+_rs_stir(void)
+{
+ u_char rnd[KEYSZ + IVSZ];
+ uint32_t rekey_fuzz = 0;
+
+ if (getentropy(rnd, sizeof rnd) == -1)
+ _getentropy_fail();
+
+ if (!rs)
+ _rs_init(rnd, sizeof(rnd));
+ else
+ _rs_rekey(rnd, sizeof(rnd));
+ explicit_bzero(rnd, sizeof(rnd)); /* discard source seed */
+
+ /* invalidate rs_buf */
+ rs->rs_have = 0;
+ memset(rsx->rs_buf, 0, sizeof(rsx->rs_buf));
+
+ /* rekey interval should not be predictable */
+ chacha_encrypt_bytes(&rsx->rs_chacha, (uint8_t *)&rekey_fuzz,
+ (uint8_t *)&rekey_fuzz, sizeof(rekey_fuzz));
+ rs->rs_count = REKEY_BASE + (rekey_fuzz % REKEY_BASE);
+}
+
+static inline void
+_rs_stir_if_needed(size_t len)
+{
+ _rs_forkdetect();
+ if (!rs || rs->rs_count <= len)
+ _rs_stir();
+ if (rs->rs_count <= len)
+ rs->rs_count = 0;
+ else
+ rs->rs_count -= len;
+}
+
+static inline void
+_rs_rekey(u_char *dat, size_t datlen)
+{
+#ifndef KEYSTREAM_ONLY
+ memset(rsx->rs_buf, 0, sizeof(rsx->rs_buf));
+#endif
+ /* fill rs_buf with the keystream */
+ chacha_encrypt_bytes(&rsx->rs_chacha, rsx->rs_buf,
+ rsx->rs_buf, sizeof(rsx->rs_buf));
+ /* mix in optional user provided data */
+ if (dat) {
+ size_t i, m;
+
+ m = minimum(datlen, KEYSZ + IVSZ);
+ for (i = 0; i < m; i++)
+ rsx->rs_buf[i] ^= dat[i];
+ }
+ /* immediately reinit for backtracking resistance */
+ _rs_init(rsx->rs_buf, KEYSZ + IVSZ);
+ memset(rsx->rs_buf, 0, KEYSZ + IVSZ);
+ rs->rs_have = sizeof(rsx->rs_buf) - KEYSZ - IVSZ;
+}
+
+static inline void
+_rs_random_buf(void *_buf, size_t n)
+{
+ u_char *buf = (u_char *)_buf;
+ u_char *keystream;
+ size_t m;
+
+ _rs_stir_if_needed(n);
+ while (n > 0) {
+ if (rs->rs_have > 0) {
+ m = minimum(n, rs->rs_have);
+ keystream = rsx->rs_buf + sizeof(rsx->rs_buf)
+ - rs->rs_have;
+ memcpy(buf, keystream, m);
+ memset(keystream, 0, m);
+ buf += m;
+ n -= m;
+ rs->rs_have -= m;
+ }
+ if (rs->rs_have == 0)
+ _rs_rekey(NULL, 0);
+ }
+}
+
+static inline void
+_rs_random_u32(uint32_t *val)
+{
+ u_char *keystream;
+
+ _rs_stir_if_needed(sizeof(*val));
+ if (rs->rs_have < sizeof(*val))
+ _rs_rekey(NULL, 0);
+ keystream = rsx->rs_buf + sizeof(rsx->rs_buf) - rs->rs_have;
+ memcpy(val, keystream, sizeof(*val));
+ memset(keystream, 0, sizeof(*val));
+ rs->rs_have -= sizeof(*val);
+}
+
+#include <pthread.h>
+static pthread_mutex_t arc4mutex = PTHREAD_MUTEX_INITIALIZER;
+
+uint32_t
+arc4random(void)
+{
+ uint32_t val;
+
+ _ARC4_LOCK();
+ _rs_random_u32(&val);
+ _ARC4_UNLOCK();
+ return val;
+}
+DEF_WEAK(arc4random);
+
+/*
+ * If we are providing arc4random, then we can provide a more efficient
+ * arc4random_buf().
+ */
+# ifndef HAVE_ARC4RANDOM_BUF
+void
+arc4random_buf(void *buf, size_t n)
+{
+ _ARC4_LOCK();
+ _rs_random_buf(buf, n);
+ _ARC4_UNLOCK();
+}
+DEF_WEAK(arc4random_buf);
+# endif /* !HAVE_ARC4RANDOM_BUF */
+#endif /* !HAVE_ARC4RANDOM */
+
+/* arc4random_buf() that uses platform arc4random() */
+#if !defined(HAVE_ARC4RANDOM_BUF) && defined(HAVE_ARC4RANDOM)
+void
+arc4random_buf(void *_buf, size_t n)
+{
+ size_t i;
+ u_int32_t r = 0;
+ char *buf = (char *)_buf;
+
+ for (i = 0; i < n; i++) {
+ if (i % 4 == 0)
+ r = arc4random();
+ buf[i] = r & 0xff;
+ r >>= 8;
+ }
+ explicit_bzero(&r, sizeof(r));
+}
+#endif /* !defined(HAVE_ARC4RANDOM_BUF) && defined(HAVE_ARC4RANDOM) */
+