1 /* 2 * Copyright (c) 2012 Alex Hornung <alex@alexhornung.com>. 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 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 13 * the documentation and/or other materials provided with the 14 * distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 17 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 18 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 19 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 20 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 21 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING, 22 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 23 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 24 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 25 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 26 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 */ 29 #include <sys/param.h> 30 #include <sys/systm.h> 31 #include <sys/kernel.h> 32 #include <sys/kobj.h> 33 #include <sys/libkern.h> 34 #include <sys/module.h> 35 #include <sys/malloc.h> 36 #include <sys/bus.h> 37 #include <sys/random.h> 38 39 #include <machine/specialreg.h> 40 41 #define RDRAND_ALIGN(p) (void *)(roundup2((uintptr_t)(p), 16)) 42 43 44 struct rdrand_softc { 45 struct callout sc_rng_co; 46 int32_t sc_rng_ticks; 47 }; 48 49 50 static void rdrand_rng_harvest(void *); 51 int rdrand_rng(uint8_t *out, int limit); 52 53 54 MALLOC_DEFINE(M_RDRAND, "rdrand_data", "RdRand Data"); 55 56 57 static void 58 rdrand_identify(driver_t *drv, device_t parent) 59 { 60 61 /* NB: order 10 is so we get attached after h/w devices */ 62 if (device_find_child(parent, "rdrand", -1) == NULL && 63 BUS_ADD_CHILD(parent, parent, 10, "rdrand", -1) == 0) 64 panic("rdrand: could not attach"); 65 } 66 67 68 static int 69 rdrand_probe(device_t dev) 70 { 71 72 if ((cpu_feature2 & CPUID2_RDRAND) == 0) { 73 device_printf(dev, "No RdRand support.\n"); 74 return (EINVAL); 75 } 76 77 device_set_desc(dev, "RdRand RNG"); 78 return 0; 79 } 80 81 82 static int 83 rdrand_attach(device_t dev) 84 { 85 struct rdrand_softc *sc; 86 87 sc = device_get_softc(dev); 88 89 if (hz > 100) 90 sc->sc_rng_ticks = hz/100; 91 else 92 sc->sc_rng_ticks = 1; 93 94 callout_init_mp(&sc->sc_rng_co); 95 callout_reset(&sc->sc_rng_co, sc->sc_rng_ticks, 96 rdrand_rng_harvest, sc); 97 98 return 0; 99 } 100 101 102 static int 103 rdrand_detach(device_t dev) 104 { 105 struct rdrand_softc *sc; 106 107 sc = device_get_softc(dev); 108 109 callout_stop_sync(&sc->sc_rng_co); 110 111 return (0); 112 } 113 114 115 static int random_count = 512; /* in bytes */ 116 117 static void 118 rdrand_rng_harvest(void *arg) 119 { 120 struct rdrand_softc *sc = arg; 121 uint8_t randomness[2048]; 122 uint8_t *arandomness; /* randomness aligned */ 123 int i, cnt; 124 125 arandomness = RDRAND_ALIGN(randomness); 126 cnt = rdrand_rng(arandomness, random_count); 127 128 for (i = 0; i < cnt; i++) 129 add_true_randomness((int)arandomness[i]); 130 131 callout_reset(&sc->sc_rng_co, sc->sc_rng_ticks, 132 rdrand_rng_harvest, sc); 133 } 134 135 136 static device_method_t rdrand_methods[] = { 137 DEVMETHOD(device_identify, rdrand_identify), 138 DEVMETHOD(device_probe, rdrand_probe), 139 DEVMETHOD(device_attach, rdrand_attach), 140 DEVMETHOD(device_detach, rdrand_detach), 141 142 DEVMETHOD_END 143 }; 144 145 146 static driver_t rdrand_driver = { 147 "rdrand", 148 rdrand_methods, 149 sizeof(struct rdrand_softc), 150 }; 151 152 static devclass_t rdrand_devclass; 153 154 DRIVER_MODULE(rdrand, nexus, rdrand_driver, rdrand_devclass, NULL, NULL); 155 MODULE_VERSION(rdrand, 1); 156 MODULE_DEPEND(rdrand, crypto, 1, 1, 1); 157