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 #include <sys/sysctl.h> 38 39 #include <machine/specialreg.h> 40 41 #define RDRAND_ALIGN(p) (void *)(roundup2((uintptr_t)(p), 16)) 42 #define RDRAND_SIZE 512 43 44 static int rdrand_debug; 45 SYSCTL_INT(_debug, OID_AUTO, rdrand, CTLFLAG_RW, &rdrand_debug, 0, 46 "Enable rdrand debugging"); 47 48 struct rdrand_softc { 49 struct callout sc_rng_co; 50 int32_t sc_rng_ticks; 51 }; 52 53 54 static void rdrand_rng_harvest(void *); 55 int rdrand_rng(uint8_t *out, long limit); 56 57 58 static void 59 rdrand_identify(driver_t *drv, device_t parent) 60 { 61 62 /* NB: order 10 is so we get attached after h/w devices */ 63 if (device_find_child(parent, "rdrand", -1) == NULL && 64 BUS_ADD_CHILD(parent, parent, 10, "rdrand", -1) == 0) 65 panic("rdrand: could not attach"); 66 } 67 68 69 static int 70 rdrand_probe(device_t dev) 71 { 72 73 if ((cpu_feature2 & CPUID2_RDRAND) == 0) { 74 device_printf(dev, "No RdRand support.\n"); 75 return (EINVAL); 76 } 77 78 device_set_desc(dev, "RdRand RNG"); 79 return 0; 80 } 81 82 83 static int 84 rdrand_attach(device_t dev) 85 { 86 struct rdrand_softc *sc; 87 88 sc = device_get_softc(dev); 89 90 if (hz > 10) 91 sc->sc_rng_ticks = hz / 10; 92 else 93 sc->sc_rng_ticks = 1; 94 95 callout_init_mp(&sc->sc_rng_co); 96 callout_reset(&sc->sc_rng_co, sc->sc_rng_ticks, 97 rdrand_rng_harvest, sc); 98 99 return 0; 100 } 101 102 103 static int 104 rdrand_detach(device_t dev) 105 { 106 struct rdrand_softc *sc; 107 108 sc = device_get_softc(dev); 109 110 callout_stop_sync(&sc->sc_rng_co); 111 112 return (0); 113 } 114 115 116 static void 117 rdrand_rng_harvest(void *arg) 118 { 119 struct rdrand_softc *sc = arg; 120 uint8_t randomness[RDRAND_SIZE + 32]; 121 uint8_t *arandomness; /* randomness aligned */ 122 int cnt; 123 124 arandomness = RDRAND_ALIGN(randomness); 125 126 cnt = rdrand_rng(arandomness, RDRAND_SIZE); 127 if (cnt > 0 && cnt < sizeof(randomness)) { 128 add_buffer_randomness_src(arandomness, cnt, RAND_SRC_RDRAND); 129 130 if (rdrand_debug) { 131 kprintf("rdrand(%d): %02x %02x %02x %02x...\n", 132 cnt, 133 arandomness[0], 134 arandomness[1], 135 arandomness[2], 136 arandomness[3]); 137 } 138 } 139 140 callout_reset(&sc->sc_rng_co, sc->sc_rng_ticks, 141 rdrand_rng_harvest, sc); 142 } 143 144 145 static device_method_t rdrand_methods[] = { 146 DEVMETHOD(device_identify, rdrand_identify), 147 DEVMETHOD(device_probe, rdrand_probe), 148 DEVMETHOD(device_attach, rdrand_attach), 149 DEVMETHOD(device_detach, rdrand_detach), 150 151 DEVMETHOD_END 152 }; 153 154 155 static driver_t rdrand_driver = { 156 "rdrand", 157 rdrand_methods, 158 sizeof(struct rdrand_softc), 159 }; 160 161 static devclass_t rdrand_devclass; 162 163 DRIVER_MODULE(rdrand, nexus, rdrand_driver, rdrand_devclass, NULL, NULL); 164 MODULE_VERSION(rdrand, 1); 165 MODULE_DEPEND(rdrand, crypto, 1, 1, 1); 166