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 "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 }