1 /*- 2 * Copyright (c) 2013, 2025, David E. O'Brien <deo@NUXI.org> 3 * Copyright (c) 2013 The FreeBSD Foundation 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/param.h> 34 #include <sys/kernel.h> 35 #include <sys/conf.h> 36 #include <sys/lock.h> 37 #include <sys/malloc.h> 38 #include <sys/module.h> 39 #include <sys/random.h> 40 #include <sys/sysctl.h> 41 #include <sys/systm.h> 42 43 #include <machine/md_var.h> 44 #include <machine/specialreg.h> 45 46 #include <dev/random/randomdev.h> 47 48 #define RETRY_COUNT 10 49 50 static u_int random_rdseed_read(void *, u_int); 51 52 static struct random_source random_rdseed = { 53 .rs_ident = "Intel Secure Key Seed", 54 .rs_source = RANDOM_PURE_RDSEED, 55 .rs_read = random_rdseed_read 56 }; 57 58 SYSCTL_NODE(_kern_random, OID_AUTO, rdseed, CTLFLAG_RW, 0, 59 "rdseed (x86) entropy source"); 60 /* XXX: kern.random.rdseed.enabled=0 also disables RDRAND */ 61 static bool enabled = true; 62 SYSCTL_BOOL(_kern_random_rdseed, OID_AUTO, enabled, CTLFLAG_RDTUN, &enabled, 0, 63 "If zero, disable the use of RDSEED."); 64 65 static bool 66 x86_rdseed_store(u_long *buf) 67 { 68 u_long rndval; 69 int retry; 70 71 retry = RETRY_COUNT; 72 __asm __volatile( 73 "1:\n\t" 74 "rdseed %1\n\t" /* read randomness into rndval */ 75 "jc 2f\n\t" /* CF is set on success, exit retry loop */ 76 "dec %0\n\t" /* otherwise, retry-- */ 77 "jne 1b\n\t" /* and loop if retries are not exhausted */ 78 "2:" 79 : "+r" (retry), "=r" (rndval) : : "cc"); 80 *buf = rndval; 81 return (retry != 0); 82 } 83 84 /* It is required that buf length is a multiple of sizeof(u_long). */ 85 static u_int 86 random_rdseed_read(void *buf, u_int c) 87 { 88 u_long *b, rndval; 89 u_int count; 90 91 KASSERT(c % sizeof(*b) == 0, ("partial read %d", c)); 92 b = buf; 93 for (count = c; count > 0; count -= sizeof(*b)) { 94 if (!x86_rdseed_store(&rndval)) 95 break; 96 *b++ = rndval; 97 } 98 return (c - count); 99 } 100 101 static int 102 rdseed_modevent(module_t mod, int type, void *unused) 103 { 104 bool has_rdseed; 105 int error = 0; 106 107 has_rdseed = (cpu_stdext_feature & CPUID_STDEXT_RDSEED); 108 109 switch (type) { 110 case MOD_LOAD: 111 if (has_rdseed && enabled) { 112 random_source_register(&random_rdseed); 113 printf("random: fast provider: \"%s\"\n", random_rdseed.rs_ident); 114 } 115 break; 116 117 case MOD_UNLOAD: 118 if (has_rdseed) 119 random_source_deregister(&random_rdseed); 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 static moduledata_t rdseed_mod = { 135 "rdseed", 136 rdseed_modevent, 137 0 138 }; 139 140 DECLARE_MODULE(rdseed, rdseed_mod, SI_SUB_RANDOM, SI_ORDER_FOURTH); 141 MODULE_VERSION(rdseed, 1); 142 MODULE_DEPEND(rdseed, random_harvestq, 1, 1, 1); 143 144 /* 145 * Intel's RDSEED Entropy Assessment Report min-entropy claim is 0.6 Shannons 146 * per bit of data output. Rrefer to the following Entropy Source Validation 147 * (ESV) certificates: 148 * 149 * E#87: Junos OS Physical Entropy Source - Broadwell EP 10-Core Die 150 * Broadwell-EP-10 FCLGA2011 Intel(R) Xeon(R) E5-2620 V4 Processor 151 * https://csrc.nist.gov/projects/cryptographic-module-validation-program/entropy-validations/certificate/87 152 * (URLs below omitted for brevity but follow same format.) 153 * 154 * E#121: Junos OS Physical Entropy Source - Intel Atom C3000 Series 155 * (Denverton) 16 Core Die with FCBGA1310 Package 156 * 157 * E#122: Junos OS Physical Entropy Source - Intel Xeon D-1500 Family 158 * (Broadwell) 8 Core Die with FCBGA1667 Package 159 * 160 * E#123: Junos OS Physical Entropy Source - Intel Xeon D-2100 Series 161 * (Skylake) 18 Core Die with FCBGA2518 Package 162 * 163 * E#141: Junos OS Physical Entropy Source - Intel Xeon D-10 Series 164 * (Ice Lake-D-10) Die with FCBGA2227 Package 165 * 166 * E#169: Junos OS Physical Entropy Source - Intel Xeon AWS-1000 v4 and 167 * E5 v4 (Broadwell EP) 15 Core Die with FCLGA2011 Package 168 */ 169