1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3 * 4 * Copyright (c) 2019 Conrad Meyer <cem@FreeBSD.org> 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25 * SUCH DAMAGE. 26 * 27 * $FreeBSD$ 28 */ 29 #pragma once 30 31 #include <sys/systm.h> 32 33 /* 34 * The root BRNG seed version, or generation. 35 * 36 * FenestrasX-aware downstream CSPRNGs (i.e., arc4random(9)) should track the 37 * generation number they seeded from, using the read_random_key(9) API below. 38 * If their current seed version is older than the root generation, they should 39 * reseed before producing output. 40 * 41 * The variable is read-only outside of the fenestrasX implementation and 42 * should be accessed using 'atomic_load_acq_64(&fxrng_root_generation)'. 43 * Reseeds are extremely infrequent, so callers may wish to hint to the 44 * compiler that a matching generation is the expected case, with 45 * __predict_true() or __predict_false(). 46 */ 47 extern uint64_t __read_mostly fxrng_root_generation; 48 49 /* 50 * A routine for generating seed/key material 51 * Bypasses random(4) for now, but conceivably could be incorporated into that. 52 */ 53 void read_random_key(void *buf, size_t nbytes, uint64_t *seed_version_out); 54