LXR qemu/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
  29static 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
  65int 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}
 111