1 /* 2 * QEMU Crypto PBKDF support (Password-Based Key Derivation Function) 3 * 4 * Copyright (c) 2015-2016 Red Hat, Inc. 5 * 6 * This library is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU Lesser General Public 8 * License as published by the Free Software Foundation; either 9 * version 2 of the License, or (at your option) any later version. 10 * 11 * This library is distributed in the hope that it will be useful, 12 * but WITHOUT ANY WARRANTY; without even the implied warranty of 13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14 * Lesser General Public License for more details. 15 * 16 * You should have received a copy of the GNU Lesser General Public 17 * License along with this library; if not, see <http://www.gnu.org/licenses/>. 18 * 19 */ 20 21 #include "qemu/osdep.h" 22 #include "crypto/pbkdf.h" 23 #ifndef _WIN32 24 #include <sys/resource.h> 25 #endif 26 27 28 static int qcrypto_pbkdf2_get_thread_cpu(unsigned long long *val_ms, 29 Error **errp) 30 { 31 #ifdef _WIN32 32 FILETIME creation_time, exit_time, kernel_time, user_time; 33 ULARGE_INTEGER thread_time; 34 35 if (!GetThreadTimes(GetCurrentThread(), &creation_time, &exit_time, 36 &kernel_time, &user_time)) { 37 error_setg(errp, "Unable to get thread CPU usage"); 38 return -1; 39 } 40 41 thread_time.LowPart = user_time.dwLowDateTime; 42 thread_time.HighPart = user_time.dwHighDateTime; 43 44 /* QuadPart is units of 100ns and we want ms as unit */ 45 *val_ms = thread_time.QuadPart / 10000ll; 46 return 0; 47 #elif defined(RUSAGE_THREAD) 48 struct rusage ru; 49 if (getrusage(RUSAGE_THREAD, &ru) < 0) { 50 error_setg_errno(errp, errno, "Unable to get thread CPU usage"); 51 return -1; 52 } 53 54 *val_ms = ((ru.ru_utime.tv_sec * 1000ll) + 55 (ru.ru_utime.tv_usec / 1000)); 56 return 0; 57 #else 58 *val_ms = 0; 59 error_setg(errp, "Unable to calculate thread CPU usage on this platform"); 60 return -1; 61 #endif 62 } 63 64 int qcrypto_pbkdf2_count_iters(QCryptoHashAlgorithm hash, 65 const uint8_t *key, size_t nkey, 66 const uint8_t *salt, size_t nsalt, 67 Error **errp) 68 { 69 uint8_t out[32]; 70 long long int iterations = (1 << 15); 71 unsigned long long delta_ms, start_ms, end_ms; 72 73 while (1) { 74 if (qcrypto_pbkdf2_get_thread_cpu(&start_ms, errp) < 0) { 75 return -1; 76 } 77 if (qcrypto_pbkdf2(hash, 78 key, nkey, 79 salt, nsalt, 80 iterations, 81 out, sizeof(out), 82 errp) < 0) { 83 return -1; 84 } 85 if (qcrypto_pbkdf2_get_thread_cpu(&end_ms, errp) < 0) { 86 return -1; 87 } 88 89 delta_ms = end_ms - start_ms; 90 91 if (delta_ms > 500) { 92 break; 93 } else if (delta_ms < 100) { 94 iterations = iterations * 10; 95 } else { 96 iterations = (iterations * 1000 / delta_ms); 97 } 98 } 99 100 iterations = iterations * 1000 / delta_ms; 101 102 if (iterations > INT32_MAX) { 103 error_setg(errp, "Iterations %lld too large for a 32-bit int", 104 iterations); 105 return -1; 106 } 107 108 return iterations; 109 } 110