nehemiah.c revision 254147
12571Srgrimes/*- 22571Srgrimes * Copyright (c) 2013 David E. O'Brien <obrien@NUXI.org> 32571Srgrimes * Copyright (c) 2004 Mark R V Murray 412580Speter * All rights reserved. 512580Speter * 62571Srgrimes * Redistribution and use in source and binary forms, with or without 72571Srgrimes * modification, are permitted provided that the following conditions 82571Srgrimes * are met: 92571Srgrimes * 1. Redistributions of source code must retain the above copyright 102571Srgrimes * notice, this list of conditions and the following disclaimer 112571Srgrimes * in this position and unchanged. 122571Srgrimes * 2. Redistributions in binary form must reproduce the above copyright 132571Srgrimes * notice, this list of conditions and the following disclaimer in the 142571Srgrimes * documentation and/or other materials provided with the distribution. 152571Srgrimes * 162571Srgrimes * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 172571Srgrimes * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 182571Srgrimes * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 192571Srgrimes * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 202571Srgrimes * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 212571Srgrimes * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 222571Srgrimes * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 232571Srgrimes * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 242571Srgrimes * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 252571Srgrimes * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 262571Srgrimes * 272571Srgrimes */ 282571Srgrimes 292571Srgrimes#include <sys/cdefs.h> 302571Srgrimes__FBSDID("$FreeBSD: head/sys/dev/random/nehemiah.c 254147 2013-08-09 15:31:50Z obrien $"); 312571Srgrimes 322571Srgrimes#include <sys/param.h> 332571Srgrimes#include <sys/time.h> 342571Srgrimes#include <sys/lock.h> 352571Srgrimes#include <sys/mutex.h> 3628223Speter#include <sys/module.h> 3784163Sdd#include <sys/selinfo.h> 3828223Speter#include <sys/systm.h> 3928223Speter#include <sys/kernel.h> 4028223Speter 4128223Speter#include <machine/pcb.h> 4219474Spst#include <machine/md_var.h> 4350472Speter#include <machine/specialreg.h> 4428223Speter 4577358Sgshapiro#include <dev/random/random_adaptors.h> 4628223Speter#include <dev/random/randomdev.h> 4748869Sjdp 4846958Sjmb#define RANDOM_BLOCK_SIZE 256 4928223Speter#define CIPHER_BLOCK_SIZE 16 5048869Sjdp 5146958Sjmbstatic void random_nehemiah_init(void); 5246958Sjmbstatic void random_nehemiah_deinit(void); 53static int random_nehemiah_read(void *, int); 54 55struct random_adaptor random_nehemiah = { 56 .ident = "Hardware, VIA Nehemiah", 57 .init = random_nehemiah_init, 58 .deinit = random_nehemiah_deinit, 59 .read = random_nehemiah_read, 60 .write = (random_write_func_t *)random_null_func, 61 .reseed = (random_reseed_func_t *)random_null_func, 62 .seeded = 1, 63}; 64 65union VIA_ACE_CW { 66 uint64_t raw; 67 struct { 68 u_int round_count : 4; 69 u_int algorithm_type : 3; 70 u_int key_generation_type : 1; 71 u_int intermediate : 1; 72 u_int decrypt : 1; 73 u_int key_size : 2; 74 u_int filler0 : 20; 75 u_int filler1 : 32; 76 u_int filler2 : 32; 77 u_int filler3 : 32; 78 } field; 79}; 80 81/* The extra 7 is to allow an 8-byte write on the last byte of the 82 * arrays. The ACE wants the AES data 16-byte/128-bit aligned, and 83 * it _always_ writes n*64 bits. The RNG does not care about alignment, 84 * and it always writes n*32 bits or n*64 bits. 85 */ 86static uint8_t key[CIPHER_BLOCK_SIZE+7] __aligned(16); 87static uint8_t iv[CIPHER_BLOCK_SIZE+7] __aligned(16); 88static uint8_t in[RANDOM_BLOCK_SIZE+7] __aligned(16); 89static uint8_t out[RANDOM_BLOCK_SIZE+7] __aligned(16); 90 91static union VIA_ACE_CW acw __aligned(16); 92 93static struct fpu_kern_ctx *fpu_ctx_save; 94 95static struct mtx random_nehemiah_mtx; 96 97/* ARGSUSED */ 98static __inline size_t 99VIA_RNG_store(void *buf) 100{ 101#ifdef __GNUCLIKE_ASM 102 uint32_t retval = 0; 103 uint32_t rate = 0; 104 105 /* The .byte line is really VIA C3 "xstore" instruction */ 106 __asm __volatile( 107 "movl $0,%%edx \n\t" 108 ".byte 0x0f, 0xa7, 0xc0" 109 : "=a" (retval), "+d" (rate), "+D" (buf) 110 : 111 : "memory" 112 ); 113 if (rate == 0) 114 return (retval&0x1f); 115#endif 116 return (0); 117} 118 119/* ARGSUSED */ 120static __inline void 121VIA_ACE_cbc(void *in, void *out, size_t count, void *key, union VIA_ACE_CW *cw, void *iv) 122{ 123#ifdef __GNUCLIKE_ASM 124 /* The .byte line is really VIA C3 "xcrypt-cbc" instruction */ 125 __asm __volatile( 126 "pushf \n\t" 127 "popf \n\t" 128 "rep \n\t" 129 ".byte 0x0f, 0xa7, 0xc8" 130 : "+a" (iv), "+c" (count), "+D" (out), "+S" (in) 131 : "b" (key), "d" (cw) 132 : "cc", "memory" 133 ); 134#endif 135} 136 137static void 138random_nehemiah_init(void) 139{ 140 acw.raw = 0ULL; 141 acw.field.round_count = 12; 142 143 mtx_init(&random_nehemiah_mtx, "random nehemiah", NULL, MTX_DEF); 144 fpu_ctx_save = fpu_kern_alloc_ctx(FPU_KERN_NORMAL); 145} 146 147void 148random_nehemiah_deinit(void) 149{ 150 151 fpu_kern_free_ctx(fpu_ctx_save); 152 mtx_destroy(&random_nehemiah_mtx); 153} 154 155static int 156random_nehemiah_read(void *buf, int c) 157{ 158 int i, error; 159 size_t count, ret; 160 uint8_t *p; 161 162 mtx_lock(&random_nehemiah_mtx); 163 error = fpu_kern_enter(curthread, fpu_ctx_save, FPU_KERN_NORMAL); 164 if (error != 0) { 165 mtx_unlock(&random_nehemiah_mtx); 166 return (0); 167 } 168 169 /* Get a random AES key */ 170 count = 0; 171 p = key; 172 do { 173 ret = VIA_RNG_store(p); 174 p += ret; 175 count += ret; 176 } while (count < CIPHER_BLOCK_SIZE); 177 178 /* Get a random AES IV */ 179 count = 0; 180 p = iv; 181 do { 182 ret = VIA_RNG_store(p); 183 p += ret; 184 count += ret; 185 } while (count < CIPHER_BLOCK_SIZE); 186 187 /* Get a block of random bytes */ 188 count = 0; 189 p = in; 190 do { 191 ret = VIA_RNG_store(p); 192 p += ret; 193 count += ret; 194 } while (count < RANDOM_BLOCK_SIZE); 195 196 /* This is a Davies-Meyer hash of the most paranoid variety; the 197 * key, IV and the data are all read directly from the hardware RNG. 198 * All of these are used precisely once. 199 */ 200 VIA_ACE_cbc(in, out, RANDOM_BLOCK_SIZE/CIPHER_BLOCK_SIZE, 201 key, &acw, iv); 202 for (i = 0; i < RANDOM_BLOCK_SIZE; i++) 203 out[i] ^= in[i]; 204 205 c = MIN(RANDOM_BLOCK_SIZE, c); 206 memcpy(buf, out, (size_t)c); 207 208 fpu_kern_leave(curthread, fpu_ctx_save); 209 mtx_unlock(&random_nehemiah_mtx); 210 return (c); 211} 212 213static int 214nehemiah_modevent(module_t mod, int type, void *unused) 215{ 216 217 switch (type) { 218 case MOD_LOAD: 219 if (via_feature_rng & VIA_HAS_RNG) { 220 random_adaptor_register("nehemiah", &random_nehemiah); 221 EVENTHANDLER_INVOKE(random_adaptor_attach, 222 &random_nehemiah); 223 return (0); 224 } else { 225#ifndef KLD_MODULE 226 if (bootverbose) 227#endif 228 printf( 229 "%s: VIA RNG feature is not present on this CPU\n", 230 random_nehemiah.ident); 231 return (0); 232 } 233 } 234 235 return (EINVAL); 236} 237 238RANDOM_ADAPTOR_MODULE(nehemiah, nehemiah_modevent, 1); 239