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/malloc.h> 38 #include <sys/sysctl.h> 39 40 #include <machine/specialreg.h> 41 42 #define RDRAND_ALIGN(p) (void *)(roundup2((uintptr_t)(p), 16)) 43 #define RDRAND_SIZE 512 44 45 static int rdrand_debug; 46 SYSCTL_INT(_debug, OID_AUTO, rdrand, CTLFLAG_RW, &rdrand_debug, 0, 47 "Enable rdrand debugging"); 48 49 struct rdrand_softc { 50 struct callout *sc_rng_co; 51 int32_t sc_rng_ticks; 52 }; 53 54 55 static void rdrand_rng_harvest(void *); 56 int rdrand_rng(uint8_t *out, long limit); 57 58 59 static void 60 rdrand_identify(driver_t *drv, device_t parent) 61 { 62 63 /* NB: order 10 is so we get attached after h/w devices */ 64 if (device_find_child(parent, "rdrand", -1) == NULL && 65 BUS_ADD_CHILD(parent, parent, 10, "rdrand", -1) == 0) 66 panic("rdrand: could not attach"); 67 } 68 69 70 static int 71 rdrand_probe(device_t dev) 72 { 73 74 if ((cpu_feature2 & CPUID2_RDRAND) == 0) { 75 device_printf(dev, "No RdRand support.\n"); 76 return (EINVAL); 77 } 78 79 device_set_desc(dev, "RdRand RNG"); 80 return 0; 81 } 82 83 84 static int 85 rdrand_attach(device_t dev) 86 { 87 struct rdrand_softc *sc; 88 int i; 89 90 sc = device_get_softc(dev); 91 92 if (hz > 10) 93 sc->sc_rng_ticks = hz / 10; 94 else 95 sc->sc_rng_ticks = 1; 96 97 sc->sc_rng_co = kmalloc(ncpus * sizeof(*sc->sc_rng_co), 98 M_TEMP, M_WAITOK | M_ZERO); 99 100 for (i = 0; i < ncpus; ++i) { 101 callout_init_mp(&sc->sc_rng_co[i]); 102 callout_reset_bycpu(&sc->sc_rng_co[i], sc->sc_rng_ticks, 103 rdrand_rng_harvest, sc, i); 104 } 105 106 return 0; 107 } 108 109 110 static int 111 rdrand_detach(device_t dev) 112 { 113 struct rdrand_softc *sc; 114 int i; 115 116 sc = device_get_softc(dev); 117 118 for (i = 0; i < ncpus; ++i) { 119 callout_terminate(&sc->sc_rng_co[i]); 120 } 121 122 return (0); 123 } 124 125 126 static void 127 rdrand_rng_harvest(void *arg) 128 { 129 struct rdrand_softc *sc = arg; 130 uint8_t randomness[RDRAND_SIZE + 32]; 131 uint8_t *arandomness; /* randomness aligned */ 132 int cnt; 133 134 arandomness = RDRAND_ALIGN(randomness); 135 136 cnt = rdrand_rng(arandomness, RDRAND_SIZE); 137 if (cnt > 0 && cnt < sizeof(randomness)) { 138 add_buffer_randomness_src(arandomness, cnt, 139 RAND_SRC_RDRAND | 140 RAND_SRCF_PCPU); 141 142 if (rdrand_debug > 0) { 143 --rdrand_debug; 144 kprintf("rdrand(%d,cpu=%d): %02x %02x %02x %02x...\n", 145 cnt, mycpu->gd_cpuid, 146 arandomness[0], 147 arandomness[1], 148 arandomness[2], 149 arandomness[3]); 150 } 151 } 152 153 callout_reset(&sc->sc_rng_co[mycpu->gd_cpuid], sc->sc_rng_ticks, 154 rdrand_rng_harvest, sc); 155 } 156 157 158 static device_method_t rdrand_methods[] = { 159 DEVMETHOD(device_identify, rdrand_identify), 160 DEVMETHOD(device_probe, rdrand_probe), 161 DEVMETHOD(device_attach, rdrand_attach), 162 DEVMETHOD(device_detach, rdrand_detach), 163 164 DEVMETHOD_END 165 }; 166 167 168 static driver_t rdrand_driver = { 169 "rdrand", 170 rdrand_methods, 171 sizeof(struct rdrand_softc), 172 }; 173 174 static devclass_t rdrand_devclass; 175 176 DRIVER_MODULE(rdrand, nexus, rdrand_driver, rdrand_devclass, NULL, NULL); 177 MODULE_VERSION(rdrand, 1); 178 MODULE_DEPEND(rdrand, crypto, 1, 1, 1); 179