1 /*- 2 * Copyright (c) 2013 The FreeBSD Foundation 3 * Copyright (c) 2013 David E. O'Brien <obrien@NUXI.org> 4 * Copyright (c) 2012 Konstantin Belousov <kib@FreeBSD.org> 5 * All rights reserved. 6 * 7 * Portions of this software were developed by Konstantin Belousov 8 * under sponsorship from the FreeBSD Foundation. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer 15 * in this position and unchanged. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 21 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 22 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 23 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 24 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 25 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 26 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 27 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 28 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 29 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 30 * 31 */ 32 33 #include <sys/cdefs.h> 34 __FBSDID("$FreeBSD$"); 35 36 #include <sys/param.h> 37 #include <sys/kernel.h> 38 #include <sys/conf.h> 39 #include <sys/lock.h> 40 #include <sys/malloc.h> 41 #include <sys/module.h> 42 #include <sys/random.h> 43 #include <sys/systm.h> 44 45 #include <machine/md_var.h> 46 #include <machine/specialreg.h> 47 48 #include <dev/random/randomdev.h> 49 #include <dev/random/randomdev_soft.h> 50 #include <dev/random/random_adaptors.h> 51 #include <dev/random/live_entropy_sources.h> 52 53 #define RETRY_COUNT 10 54 55 static u_int random_ivy_read(void *, u_int); 56 57 static struct live_entropy_source random_ivy = { 58 .les_ident = "Intel Secure Key RNG", 59 .les_source = RANDOM_PURE_RDRAND, 60 .les_read = random_ivy_read 61 }; 62 63 static inline int 64 ivy_rng_store(long *buf) 65 { 66 #ifdef __GNUCLIKE_ASM 67 long tmp; 68 int retry; 69 70 retry = RETRY_COUNT; 71 __asm __volatile( 72 "1:\n\t" 73 "rdrand %2\n\t" /* read randomness into tmp */ 74 "jb 2f\n\t" /* CF is set on success, exit retry loop */ 75 "dec %0\n\t" /* otherwise, retry-- */ 76 "jne 1b\n\t" /* and loop if retries are not exhausted */ 77 "jmp 3f\n" /* failure, retry is 0, used as return value */ 78 "2:\n\t" 79 "mov %2,%1\n\t" /* *buf = tmp */ 80 "3:" 81 : "+q" (retry), "=m" (*buf), "+q" (tmp) : : "cc"); 82 return (retry); 83 #else /* __GNUCLIKE_ASM */ 84 return (0); 85 #endif 86 } 87 88 /* It is specifically allowed that buf is a multiple of sizeof(long) */ 89 static u_int 90 random_ivy_read(void *buf, u_int c) 91 { 92 long *b; 93 u_int count; 94 95 KASSERT(c % sizeof(*b) == 0, ("partial read %d", c)); 96 b = buf; 97 for (count = c; count > 0; count -= sizeof(*b)) { 98 if (ivy_rng_store(b++) == 0) 99 break; 100 } 101 return (c - count); 102 } 103 104 static int 105 rdrand_modevent(module_t mod, int type, void *unused) 106 { 107 int error = 0; 108 109 switch (type) { 110 case MOD_LOAD: 111 if (cpu_feature2 & CPUID2_RDRAND) { 112 live_entropy_source_register(&random_ivy); 113 printf("random: live provider: \"%s\"\n", random_ivy.les_ident); 114 } 115 break; 116 117 case MOD_UNLOAD: 118 if (cpu_feature2 & CPUID2_RDRAND) 119 live_entropy_source_deregister(&random_ivy); 120 break; 121 122 case MOD_SHUTDOWN: 123 break; 124 125 default: 126 error = EOPNOTSUPP; 127 break; 128 129 } 130 131 return (error); 132 } 133 134 DEV_MODULE(rdrand, rdrand_modevent, NULL); 135 MODULE_VERSION(rdrand, 1); 136 MODULE_DEPEND(rdrand, random_adaptors, 1, 1, 1); 137