1 /*- 2 * Copyright (c) 2013 Mark R V Murray 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 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer 10 * in this position and unchanged. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 * 26 */ 27 28 #include <sys/cdefs.h> 29 __FBSDID("$FreeBSD$"); 30 31 #include <sys/param.h> 32 #include <sys/kernel.h> 33 #include <sys/lock.h> 34 #include <sys/malloc.h> 35 #include <sys/module.h> 36 #include <sys/random.h> 37 #include <sys/selinfo.h> 38 #include <sys/systm.h> 39 40 #include <machine/segments.h> 41 #include <machine/pcb.h> 42 #include <machine/md_var.h> 43 #include <machine/specialreg.h> 44 45 #include <dev/random/randomdev.h> 46 #include <dev/random/randomdev_soft.h> 47 #include <dev/random/random_harvestq.h> 48 #include <dev/random/live_entropy_sources.h> 49 #include <dev/random/random_adaptors.h> 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 static struct random_hardware_source random_nehemiah = { 56 .ident = "Hardware, VIA Nehemiah Padlock RNG", 57 .source = RANDOM_PURE_NEHEMIAH, 58 .read = random_nehemiah_read 59 }; 60 61 /* TODO: now that the Davies-Meyer hash is gone and we only use 62 * the 'xstore' instruction, do we still need to preserve the 63 * FPU state with fpu_kern_(enter|leave)() ? 64 */ 65 static struct fpu_kern_ctx *fpu_ctx_save; 66 67 /* This H/W source never stores more than 8 bytes in one go */ 68 /* ARGSUSED */ 69 static __inline size_t 70 VIA_RNG_store(void *buf) 71 { 72 uint32_t retval = 0; 73 uint32_t rate = 0; 74 75 #ifdef __GNUCLIKE_ASM 76 __asm __volatile( 77 "movl $0,%%edx\n\t" 78 ".byte 0x0f, 0xa7, 0xc0" /* xstore */ 79 : "=a" (retval), "+d" (rate), "+D" (buf) 80 : 81 : "memory" 82 ); 83 #endif 84 if (rate == 0) 85 return (retval&0x1f); 86 return (0); 87 } 88 89 static void 90 random_nehemiah_init(void) 91 { 92 93 fpu_ctx_save = fpu_kern_alloc_ctx(FPU_KERN_NORMAL); 94 } 95 96 static void 97 random_nehemiah_deinit(void) 98 { 99 100 fpu_kern_free_ctx(fpu_ctx_save); 101 } 102 103 static int 104 random_nehemiah_read(void *buf, int c) 105 { 106 uint8_t *b; 107 size_t count, ret; 108 uint64_t tmp; 109 110 if ((fpu_kern_enter(curthread, fpu_ctx_save, FPU_KERN_NORMAL) == 0)) { 111 b = buf; 112 for (count = c; count > 0; count -= ret) { 113 ret = MIN(VIA_RNG_store(&tmp), count); 114 memcpy(b, &tmp, ret); 115 b += ret; 116 } 117 fpu_kern_leave(curthread, fpu_ctx_save); 118 } 119 else 120 c = 0; 121 122 return (c); 123 } 124 125 static int 126 nehemiah_modevent(module_t mod, int type, void *unused) 127 { 128 int error = 0; 129 130 switch (type) { 131 case MOD_LOAD: 132 if (via_feature_rng & VIA_HAS_RNG) { 133 live_entropy_source_register(&random_nehemiah); 134 random_nehemiah_init(); 135 } else 136 #ifndef KLD_MODULE 137 if (bootverbose) 138 #endif 139 printf("%s: VIA Padlock RNG not present\n", 140 random_nehemiah.ident); 141 break; 142 143 case MOD_UNLOAD: 144 if (via_feature_rng & VIA_HAS_RNG) 145 random_nehemiah_deinit(); 146 live_entropy_source_deregister(&random_nehemiah); 147 break; 148 149 case MOD_SHUTDOWN: 150 break; 151 152 default: 153 error = EOPNOTSUPP; 154 break; 155 156 } 157 158 return (error); 159 } 160 161 LIVE_ENTROPY_SRC_MODULE(nehemiah, nehemiah_modevent, 1); 162