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/*
* Copyright (C) 2011 Google Inc.
* Copyright (C) 2017 Yusuke Suzuki <utatane.tea@gmail.com>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY GOOGLE, INC. ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "config.h"
#include <wtf/RandomDevice.h>
#include <stdlib.h>
#if !OS(DARWIN) && !OS(FUCHSIA) && OS(UNIX)
#include <errno.h>
#include <fcntl.h>
#include <unistd.h>
#endif
#if OS(WINDOWS)
#include <windows.h>
#include <wincrypt.h> // windows.h must be included before wincrypt.h.
#endif
#if OS(DARWIN)
#include <CommonCrypto/CommonCryptor.h>
#include <CommonCrypto/CommonRandom.h>
#endif
#if OS(FUCHSIA)
#include <zircon/syscalls.h>
#endif
namespace WTF {
#if !OS(DARWIN) && !OS(FUCHSIA) && OS(UNIX)
NEVER_INLINE NO_RETURN_DUE_TO_CRASH static void crashUnableToOpenURandom()
{
CRASH();
}
NEVER_INLINE NO_RETURN_DUE_TO_CRASH static void crashUnableToReadFromURandom()
{
CRASH();
}
#endif
#if !OS(DARWIN) && !OS(FUCHSIA) && !OS(WINDOWS)
RandomDevice::RandomDevice()
{
int ret = 0;
do {
ret = open("/dev/urandom", O_RDONLY, 0);
} while (ret == -1 && errno == EINTR);
m_fd = ret;
if (m_fd < 0)
crashUnableToOpenURandom(); // We need /dev/urandom for this API to work...
}
#endif
#if !OS(DARWIN) && !OS(FUCHSIA) && !OS(WINDOWS)
RandomDevice::~RandomDevice()
{
close(m_fd);
}
#endif
// FIXME: Make this call fast by creating the pool in RandomDevice.
// https://bugs.webkit.org/show_bug.cgi?id=170190
void RandomDevice::cryptographicallyRandomValues(std::span<uint8_t> buffer)
{
#if OS(DARWIN)
RELEASE_ASSERT(!CCRandomGenerateBytes(buffer.data(), buffer.size()));
#elif OS(FUCHSIA)
zx_cprng_draw(buffer.data(), buffer.size());
#elif OS(UNIX)
ssize_t amountRead = 0;
while (static_cast<size_t>(amountRead) < buffer.size()) {
WTF_ALLOW_UNSAFE_BUFFER_USAGE_BEGIN
ssize_t currentRead = read(m_fd, buffer.data() + amountRead, buffer.size() - amountRead);
WTF_ALLOW_UNSAFE_BUFFER_USAGE_END
// We need to check for both EAGAIN and EINTR since on some systems /dev/urandom
// is blocking and on others it is non-blocking.
if (currentRead == -1) {
if (!(errno == EAGAIN || errno == EINTR))
crashUnableToReadFromURandom();
} else
amountRead += currentRead;
}
#elif OS(WINDOWS)
// FIXME: We cannot ensure that Cryptographic Service Provider context and CryptGenRandom are safe across threads.
// If it is safe, we can acquire context per RandomDevice.
HCRYPTPROV hCryptProv = 0;
if (!CryptAcquireContext(&hCryptProv, nullptr, MS_DEF_PROV, PROV_RSA_FULL, CRYPT_VERIFYCONTEXT))
CRASH();
if (!CryptGenRandom(hCryptProv, buffer.size(), buffer.data()))
CRASH();
CryptReleaseContext(hCryptProv, 0);
#else
#error "This configuration doesn't have a strong source of randomness."
// WARNING: When adding new sources of OS randomness, the randomness must
// be of cryptographic quality!
#endif
}
}
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