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-rw-r--r--lib/util/arc4random.c206
1 files changed, 206 insertions, 0 deletions
diff --git a/lib/util/arc4random.c b/lib/util/arc4random.c
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+++ b/lib/util/arc4random.c
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+/* $OpenBSD: arc4random.c,v 1.54 2015/09/13 08:31:47 guenther Exp $ */
+
+/*
+ * SPDX-License-Identifier: ISC
+ *
+ * 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.
+ */
+
+/*
+ * This is an open source non-commercial project. Dear PVS-Studio, please check it.
+ * PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
+ */
+
+/*
+ * ChaCha based random number generator for OpenBSD.
+ */
+
+#include <config.h>
+
+#ifndef HAVE_ARC4RANDOM
+
+#ifdef HAVE_SYS_RANDOM_H
+# include <sys/random.h>
+#endif
+
+#include <fcntl.h>
+#include <limits.h>
+#include <signal.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#if defined(HAVE_STDINT_H)
+# include <stdint.h>
+#elif defined(HAVE_INTTYPES_H)
+# include <inttypes.h>
+#endif
+
+#include "sudo_compat.h"
+#include "sudo_fatal.h"
+#include "sudo_rand.h"
+
+#define KEYSTREAM_ONLY
+#include "chacha_private.h"
+
+#define minimum(a, b) ((a) < (b) ? (a) : (b))
+
+#ifdef __GNUC__
+# define inline __inline
+#else /* !__GNUC__ */
+# define inline
+#endif /* !__GNUC__ */
+
+/* Sudo isn't multithreaded */
+#define _ARC4_LOCK()
+#define _ARC4_UNLOCK()
+
+#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(unsigned char *dat, size_t datlen);
+
+static inline void
+_rs_init(unsigned 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)
+{
+ unsigned char rnd[KEYSZ + IVSZ];
+
+ if (getentropy(rnd, sizeof rnd) == -1)
+ sudo_fatal_nodebug("getentropy");
+
+ if (!rs_initialized) {
+ rs_initialized = 1;
+ _rs_init(rnd, sizeof(rnd));
+ } else
+ _rs_rekey(rnd, sizeof(rnd));
+ explicit_bzero(rnd, sizeof(rnd)); /* discard source seed */
+
+ /* invalidate rs_buf */
+ rs_have = 0;
+ memset(rs_buf, 0, sizeof(rs_buf));
+
+ 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(unsigned char *dat, size_t datlen)
+{
+#ifndef KEYSTREAM_ONLY
+ memset(rs_buf, 0, sizeof(rs_buf));
+#endif
+ /* fill rs_buf with the keystream */
+ chacha_encrypt_bytes(&rs, rs_buf, rs_buf, sizeof(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++)
+ rs_buf[i] ^= dat[i];
+ }
+ /* immediately reinit for backtracking resistance */
+ _rs_init(rs_buf, KEYSZ + IVSZ);
+ memset(rs_buf, 0, KEYSZ + IVSZ); // -V::512, 1086
+ rs_have = sizeof(rs_buf) - KEYSZ - IVSZ;
+}
+
+static inline void
+_rs_random_buf(void *_buf, size_t n)
+{
+ unsigned char *buf = _buf;
+ unsigned char *keystream;
+ size_t m;
+
+ _rs_stir_if_needed(n);
+ while (n > 0) {
+ if (rs_have > 0) {
+ m = minimum(n, rs_have);
+ keystream = rs_buf + sizeof(rs_buf) - rs_have;
+ memcpy(buf, keystream, m);
+ memset(keystream, 0, m);
+ buf += m;
+ n -= m;
+ rs_have -= m;
+ }
+ if (rs_have == 0)
+ _rs_rekey(NULL, 0);
+ }
+}
+
+static inline void
+_rs_random_u32(uint32_t *val)
+{
+ unsigned char *keystream;
+
+ _rs_stir_if_needed(sizeof(*val));
+ if (rs_have < sizeof(*val))
+ _rs_rekey(NULL, 0);
+ keystream = rs_buf + sizeof(rs_buf) - rs_have;
+ memcpy(val, keystream, sizeof(*val));
+ memset(keystream, 0, sizeof(*val));
+ rs_have -= sizeof(*val);
+}
+
+uint32_t
+sudo_arc4random(void)
+{
+ uint32_t val;
+
+ _ARC4_LOCK();
+ _rs_random_u32(&val);
+ _ARC4_UNLOCK();
+ return val;
+}
+
+void
+sudo_arc4random_buf(void *buf, size_t n)
+{
+ _ARC4_LOCK();
+ _rs_random_buf(buf, n);
+ _ARC4_UNLOCK();
+}
+
+#endif /* HAVE_ARC4RANDOM */