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/bus.h> 36 #include <sys/random.h> 37 38 #include <machine/specialreg.h> 39 40 #define RDRAND_ALIGN(p) (void *)(roundup2((uintptr_t)(p), 16)) 41 42 43 struct rdrand_softc { 44 struct callout sc_rng_co; 45 int32_t sc_rng_ticks; 46 }; 47 48 49 static void rdrand_rng_harvest(void *); 50 int rdrand_rng(uint8_t *out, int limit); 51 52 53 static void 54 rdrand_identify(driver_t *drv, device_t parent) 55 { 56 57 /* NB: order 10 is so we get attached after h/w devices */ 58 if (device_find_child(parent, "rdrand", -1) == NULL && 59 BUS_ADD_CHILD(parent, parent, 10, "rdrand", -1) == 0) 60 panic("rdrand: could not attach"); 61 } 62 63 64 static int 65 rdrand_probe(device_t dev) 66 { 67 68 if ((cpu_feature2 & CPUID2_RDRAND) == 0) { 69 device_printf(dev, "No RdRand support.\n"); 70 return (EINVAL); 71 } 72 73 device_set_desc(dev, "RdRand RNG"); 74 return 0; 75 } 76 77 78 static int 79 rdrand_attach(device_t dev) 80 { 81 struct rdrand_softc *sc; 82 83 sc = device_get_softc(dev); 84 85 if (hz > 100) 86 sc->sc_rng_ticks = hz/100; 87 else 88 sc->sc_rng_ticks = 1; 89 90 callout_init_mp(&sc->sc_rng_co); 91 callout_reset(&sc->sc_rng_co, sc->sc_rng_ticks, 92 rdrand_rng_harvest, sc); 93 94 return 0; 95 } 96 97 98 static int 99 rdrand_detach(device_t dev) 100 { 101 struct rdrand_softc *sc; 102 103 sc = device_get_softc(dev); 104 105 callout_stop_sync(&sc->sc_rng_co); 106 107 return (0); 108 } 109 110 111 static int random_count = 512; /* in bytes */ 112 113 static void 114 rdrand_rng_harvest(void *arg) 115 { 116 struct rdrand_softc *sc = arg; 117 uint8_t randomness[2048]; 118 uint8_t *arandomness; /* randomness aligned */ 119 int i, cnt; 120 121 arandomness = RDRAND_ALIGN(randomness); 122 cnt = rdrand_rng(arandomness, random_count); 123 124 for (i = 0; i < cnt; i++) 125 add_true_randomness((int)arandomness[i]); 126 127 callout_reset(&sc->sc_rng_co, sc->sc_rng_ticks, 128 rdrand_rng_harvest, sc); 129 } 130 131 132 static device_method_t rdrand_methods[] = { 133 DEVMETHOD(device_identify, rdrand_identify), 134 DEVMETHOD(device_probe, rdrand_probe), 135 DEVMETHOD(device_attach, rdrand_attach), 136 DEVMETHOD(device_detach, rdrand_detach), 137 138 DEVMETHOD_END 139 }; 140 141 142 static driver_t rdrand_driver = { 143 "rdrand", 144 rdrand_methods, 145 sizeof(struct rdrand_softc), 146 }; 147 148 static devclass_t rdrand_devclass; 149 150 DRIVER_MODULE(rdrand, nexus, rdrand_driver, rdrand_devclass, NULL, NULL); 151 MODULE_VERSION(rdrand, 1); 152 MODULE_DEPEND(rdrand, crypto, 1, 1, 1); 153