1 /* $NetBSD: efirng.c,v 1.3 2021/06/22 10:19:35 jmcneill Exp $ */ 2 3 /*- 4 * Copyright (c) 2020 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 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 NETBSD FOUNDATION, INC. AND CONTRIBUTORS 17 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 18 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 19 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 20 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 26 * POSSIBILITY OF SUCH DAMAGE. 27 */ 28 29 /* 30 * UEFI Forum, Inc.: UEFI Specification, Version 2.8 Errata A, February 31 * 2020, Sec. 37.5 EFI Random Number Generator Protocol, pp. 2158--2162 32 * https://uefi.org/sites/default/files/resources/UEFI_Spec_2_8_A_Feb14.pdf 33 */ 34 35 #include "efirng.h" 36 37 #include "efiboot.h" 38 39 static EFI_GUID RngProtocolGuid = EFI_RNG_PROTOCOL_GUID; 40 static EFI_GUID RngAlgorithmRawGuid = EFI_RNG_ALGORITHM_RAW; 41 static EFI_RNG_PROTOCOL *rng; 42 43 #ifndef EFIBOOT_DEBUG 44 #define DPRINT(...) __nothing 45 #else 46 #define DPRINT Print 47 #endif 48 49 static const struct { 50 EFI_GUID guid; 51 const CHAR16 *name; 52 } algname[] = { 53 {EFI_RNG_ALGORITHM_SP800_90_HASH_256_GUID, 54 L"NIST SP800-90 Hash_DRBG SHA-256"}, 55 {EFI_RNG_ALGORITHM_SP800_90_HMAC_256_GUID, 56 L"NIST SP800-90 HMAC_DRBG SHA-256"}, 57 {EFI_RNG_ALGORITHM_SP800_90_CTR_256_GUID, 58 L"NIST SP800-90 CTR_DRBG AES-256"}, 59 {EFI_RNG_ALGORITHM_X9_31_3DES_GUID, L"ANSI X9.31 3DES"}, 60 {EFI_RNG_ALGORITHM_X9_31_AES_GUID, L"ANSI X9.31 AES"}, 61 {EFI_RNG_ALGORITHM_RAW, L"raw"}, 62 }; 63 64 void 65 efi_rng_probe(void) 66 { 67 EFI_STATUS status; 68 69 /* Get the RNG protocol. */ 70 status = LibLocateProtocol(&RngProtocolGuid, (void **)&rng); 71 if (EFI_ERROR(status)) { 72 DPRINT(L"efirng: protocol: %r\n", status); 73 rng = NULL; 74 return; 75 } 76 } 77 78 void 79 efi_rng_show(void) 80 { 81 EFI_RNG_ALGORITHM alglist[10]; 82 UINTN i, j, alglistsz = sizeof(alglist); 83 EFI_STATUS status; 84 85 if (!efi_rng_available()) 86 return; 87 88 /* Query the list of supported algorithms. */ 89 status = uefi_call_wrapper(rng->GetInfo, 3, rng, &alglistsz, alglist); 90 if (EFI_ERROR(status)) { 91 Print(L"RNG: GetInfo: %r\n", status); 92 return; 93 } 94 95 /* Print the list of supported algorithms. */ 96 for (i = 0; i < alglistsz/sizeof(alglist[0]); i++) { 97 const CHAR16 *name = L"[unknown]"; 98 for (j = 0; j < __arraycount(algname); j++) { 99 if (memcmp(&alglist[i], &algname[j].guid, 100 sizeof(EFI_GUID)) == 0) { 101 name = algname[j].name; 102 break; 103 } 104 } 105 Print(L"RNG: %s (%g)\n", name, &alglist[i]); 106 } 107 } 108 109 int 110 efi_rng_available(void) 111 { 112 113 return rng != NULL; 114 } 115 116 int 117 efi_rng(void *buf, UINTN len) 118 { 119 EFI_STATUS status; 120 121 if (!efi_rng_available()) 122 return EIO; 123 124 status = uefi_call_wrapper(rng->GetRNG, 4, rng, &RngAlgorithmRawGuid, 125 len, buf); 126 if (status == EFI_UNSUPPORTED) { 127 /* 128 * Fall back to any supported RNG `algorithm' even 129 * though we would prefer raw samples. 130 */ 131 status = uefi_call_wrapper(rng->GetRNG, 4, rng, NULL, len, buf); 132 } 133 if (EFI_ERROR(status)) { 134 DPRINT(L"efirng: GetRNG: %r\n", status); 135 return EIO; 136 } 137 138 return 0; 139 } 140