crypto/pbkdf.c

   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 "qapi/error.h"
  23 #include "crypto/pbkdf.h"
  24 #ifndef _WIN32
  25 #include <sys/resource.h>
  26 #endif
  27
  28
  29 static int qcrypto_pbkdf2_get_thread_cpu(unsigned long long *val_ms,
  30                                          Error **errp)
  31 {
  32 #ifdef _WIN32
  33     FILETIME creation_time, exit_time, kernel_time, user_time;
  34     ULARGE_INTEGER thread_time;
  35
  36     if (!GetThreadTimes(GetCurrentThread(), &creation_time, &exit_time,
  37                         &kernel_time, &user_time)) {
  38         error_setg(errp, "Unable to get thread CPU usage");
  39         return -1;
  40     }
  41
  42     thread_time.LowPart = user_time.dwLowDateTime;
  43     thread_time.HighPart = user_time.dwHighDateTime;
  44
  45     /* QuadPart is units of 100ns and we want ms as unit */
  46     *val_ms = thread_time.QuadPart / 10000ll;
  47     return 0;
  48 #elif defined(RUSAGE_THREAD)
  49     struct rusage ru;
  50     if (getrusage(RUSAGE_THREAD, &ru) < 0) {
  51         error_setg_errno(errp, errno, "Unable to get thread CPU usage");
  52         return -1;
  53     }
  54
  55     *val_ms = ((ru.ru_utime.tv_sec * 1000ll) +
  56                (ru.ru_utime.tv_usec / 1000));
  57     return 0;
  58 #else
  59     *val_ms = 0;
  60     error_setg(errp, "Unable to calculate thread CPU usage on this platform");
  61     return -1;
  62 #endif
  63 }
  64
  65 int qcrypto_pbkdf2_count_iters(QCryptoHashAlgorithm hash,
  66                                const uint8_t *key, size_t nkey,
  67                                const uint8_t *salt, size_t nsalt,
  68                                Error **errp)
  69 {
  70     uint8_t out[32];
  71     long long int iterations = (1 << 15);
  72     unsigned long long delta_ms, start_ms, end_ms;
  73
  74     while (1) {
  75         if (qcrypto_pbkdf2_get_thread_cpu(&start_ms, errp) < 0) {
  76             return -1;
  77         }
  78         if (qcrypto_pbkdf2(hash,
  79                            key, nkey,
  80                            salt, nsalt,
  81                            iterations,
  82                            out, sizeof(out),
  83                            errp) < 0) {
  84             return -1;
  85         }
  86         if (qcrypto_pbkdf2_get_thread_cpu(&end_ms, errp) < 0) {
  87             return -1;
  88         }
  89
  90         delta_ms = end_ms - start_ms;
  91
  92         if (delta_ms > 500) {
  93             break;
  94         } else if (delta_ms < 100) {
  95             iterations = iterations * 10;
  96         } else {
  97             iterations = (iterations * 1000 / delta_ms);
  98         }
  99     }
 100
 101     iterations = iterations * 1000 / delta_ms;
 102
 103     if (iterations > INT32_MAX) {
 104         error_setg(errp, "Iterations %lld too large for a 32-bit int",
 105                    iterations);
 106         return -1;
 107     }
 108
 109     return iterations;
 110 }