122 lines
3.9 KiB
C++
122 lines
3.9 KiB
C++
/*
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* Copyright (C) 2011 Google Inc.
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* Copyright (C) 2017 Yusuke Suzuki <utatane.tea@gmail.com>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY GOOGLE, INC. ``AS IS'' AND ANY
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* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
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* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "config.h"
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#include <wtf/RandomDevice.h>
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#include <stdlib.h>
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#if !OS(DARWIN) && !OS(FUCHSIA) && OS(UNIX)
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#include <errno.h>
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#include <fcntl.h>
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#include <unistd.h>
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#endif
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#if OS(WINDOWS)
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#include <windows.h>
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#include <wincrypt.h> // windows.h must be included before wincrypt.h.
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#endif
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#if OS(DARWIN)
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#include <CommonCrypto/CommonRandom.h>
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#endif
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#if OS(FUCHSIA)
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#include <zircon/syscalls.h>
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#endif
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namespace WTF {
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#if !OS(DARWIN) && !OS(FUCHSIA) && OS(UNIX)
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NEVER_INLINE NO_RETURN_DUE_TO_CRASH static void crashUnableToOpenURandom()
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{
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CRASH();
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}
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NEVER_INLINE NO_RETURN_DUE_TO_CRASH static void crashUnableToReadFromURandom()
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{
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CRASH();
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}
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#endif
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#if !OS(DARWIN) && !OS(FUCHSIA) && !OS(WINDOWS)
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RandomDevice::RandomDevice()
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{
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int ret = 0;
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do {
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ret = open("/dev/urandom", O_RDONLY, 0);
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} while (ret == -1 && errno == EINTR);
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m_fd = ret;
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if (m_fd < 0)
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crashUnableToOpenURandom(); // We need /dev/urandom for this API to work...
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}
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#endif
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#if !OS(DARWIN) && !OS(FUCHSIA) && !OS(WINDOWS)
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RandomDevice::~RandomDevice()
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{
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close(m_fd);
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}
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#endif
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// FIXME: Make this call fast by creating the pool in RandomDevice.
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// https://bugs.webkit.org/show_bug.cgi?id=170190
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void RandomDevice::cryptographicallyRandomValues(unsigned char* buffer, size_t length)
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{
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#if OS(DARWIN)
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RELEASE_ASSERT(!CCRandomGenerateBytes(buffer, length));
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#elif OS(FUCHSIA)
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zx_cprng_draw(buffer, length);
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#elif OS(UNIX)
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ssize_t amountRead = 0;
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while (static_cast<size_t>(amountRead) < length) {
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ssize_t currentRead = read(m_fd, buffer + amountRead, length - amountRead);
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// We need to check for both EAGAIN and EINTR since on some systems /dev/urandom
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// is blocking and on others it is non-blocking.
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if (currentRead == -1) {
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if (!(errno == EAGAIN || errno == EINTR))
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crashUnableToReadFromURandom();
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} else
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amountRead += currentRead;
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}
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#elif OS(WINDOWS)
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// FIXME: We cannot ensure that Cryptographic Service Provider context and CryptGenRandom are safe across threads.
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// If it is safe, we can acquire context per RandomDevice.
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HCRYPTPROV hCryptProv = 0;
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if (!CryptAcquireContext(&hCryptProv, nullptr, MS_DEF_PROV, PROV_RSA_FULL, CRYPT_VERIFYCONTEXT))
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CRASH();
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if (!CryptGenRandom(hCryptProv, length, buffer))
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CRASH();
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CryptReleaseContext(hCryptProv, 0);
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#else
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#error "This configuration doesn't have a strong source of randomness."
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// WARNING: When adding new sources of OS randomness, the randomness must
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// be of cryptographic quality!
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#endif
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}
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}
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