1 /*- 2 * Copyright (c) 2013 David E. O'Brien <obrien@NUXI.org> 3 * Copyright (c) 2004 Mark R V Murray 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer 11 * in this position and unchanged. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 * 27 */ 28 29 #include <sys/cdefs.h> 30 __FBSDID("$FreeBSD$"); 31 32 #include <sys/param.h> 33 #include <sys/time.h> 34 #include <sys/lock.h> 35 #include <sys/mutex.h> 36 #include <sys/module.h> 37 #include <sys/selinfo.h> 38 #include <sys/systm.h> 39 #include <sys/kernel.h> 40 41 #include <machine/pcb.h> 42 #include <machine/md_var.h> 43 #include <machine/specialreg.h> 44 45 #include <dev/random/random_adaptors.h> 46 #include <dev/random/randomdev.h> 47 48 #define RANDOM_BLOCK_SIZE 256 49 #define CIPHER_BLOCK_SIZE 16 50 51 static void random_nehemiah_init(void); 52 static void random_nehemiah_deinit(void); 53 static int random_nehemiah_read(void *, int); 54 55 struct 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 65 union 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 */ 86 static uint8_t key[CIPHER_BLOCK_SIZE+7] __aligned(16); 87 static uint8_t iv[CIPHER_BLOCK_SIZE+7] __aligned(16); 88 static uint8_t in[RANDOM_BLOCK_SIZE+7] __aligned(16); 89 static uint8_t out[RANDOM_BLOCK_SIZE+7] __aligned(16); 90 91 static union VIA_ACE_CW acw __aligned(16); 92 93 static struct fpu_kern_ctx *fpu_ctx_save; 94 95 static struct mtx random_nehemiah_mtx; 96 97 /* ARGSUSED */ 98 static __inline size_t 99 VIA_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 */ 120 static __inline void 121 VIA_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 } 136 137 static void 138 random_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 } 146 147 void 148 random_nehemiah_deinit(void) 149 { 150 151 fpu_kern_free_ctx(fpu_ctx_save); 152 mtx_destroy(&random_nehemiah_mtx); 153 } 154 155 static int 156 random_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 } 212 213 static int 214 nehemiah_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 } 237 238 RANDOM_ADAPTOR_MODULE(nehemiah, nehemiah_modevent, 1); 239