1/*
2 * Copyright (C) 2011 Google Inc.
3 * Copyright (C) 2017 Yusuke Suzuki <utatane.tea@gmail.com>
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY GOOGLE, INC. ``AS IS'' AND ANY
15 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
17 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
18 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
19 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
20 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
21 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
22 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
24 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27#include "config.h"
28#include <wtf/RandomDevice.h>
29
30#include <stdint.h>
31#include <stdlib.h>
32
33#if !OS(DARWIN) && !OS(FUCHSIA) && OS(UNIX)
34#include <errno.h>
35#include <fcntl.h>
36#include <unistd.h>
37#endif
38
39#if OS(WINDOWS)
40#include <windows.h>
41#include <wincrypt.h> // windows.h must be included before wincrypt.h.
42#endif
43
44#if OS(DARWIN)
45#include <CommonCrypto/CommonCryptoError.h>
46#include <CommonCrypto/CommonRandom.h>
47#endif
48
49#if OS(FUCHSIA)
50#include <zircon/syscalls.h>
51#endif
52
53namespace WTF {
54
55#if !OS(DARWIN) && !OS(FUCHSIA) && OS(UNIX)
56NEVER_INLINE NO_RETURN_DUE_TO_CRASH static void crashUnableToOpenURandom()
57{
58 CRASH();
59}
60
61NEVER_INLINE NO_RETURN_DUE_TO_CRASH static void crashUnableToReadFromURandom()
62{
63 CRASH();
64}
65#endif
66
67#if !OS(DARWIN) && !OS(FUCHSIA) && !OS(WINDOWS)
68RandomDevice::RandomDevice()
69{
70 int ret = 0;
71 do {
72 ret = open("/dev/urandom", O_RDONLY, 0);
73 } while (ret == -1 && errno == EINTR);
74 m_fd = ret;
75 if (m_fd < 0)
76 crashUnableToOpenURandom(); // We need /dev/urandom for this API to work...
77}
78#endif
79
80#if !OS(DARWIN) && !OS(FUCHSIA) && !OS(WINDOWS)
81RandomDevice::~RandomDevice()
82{
83 close(m_fd);
84}
85#endif
86
87// FIXME: Make this call fast by creating the pool in RandomDevice.
88// https://bugs.webkit.org/show_bug.cgi?id=170190
89void RandomDevice::cryptographicallyRandomValues(unsigned char* buffer, size_t length)
90{
91#if OS(DARWIN)
92 RELEASE_ASSERT(!CCRandomGenerateBytes(buffer, length));
93#elif OS(FUCHSIA)
94 zx_cprng_draw(buffer, length);
95#elif OS(UNIX)
96 ssize_t amountRead = 0;
97 while (static_cast<size_t>(amountRead) < length) {
98 ssize_t currentRead = read(m_fd, buffer + amountRead, length - amountRead);
99 // We need to check for both EAGAIN and EINTR since on some systems /dev/urandom
100 // is blocking and on others it is non-blocking.
101 if (currentRead == -1) {
102 if (!(errno == EAGAIN || errno == EINTR))
103 crashUnableToReadFromURandom();
104 } else
105 amountRead += currentRead;
106 }
107#elif OS(WINDOWS)
108 // FIXME: We cannot ensure that Cryptographic Service Provider context and CryptGenRandom are safe across threads.
109 // If it is safe, we can acquire context per RandomDevice.
110 HCRYPTPROV hCryptProv = 0;
111 if (!CryptAcquireContext(&hCryptProv, 0, MS_DEF_PROV, PROV_RSA_FULL, CRYPT_VERIFYCONTEXT))
112 CRASH();
113 if (!CryptGenRandom(hCryptProv, length, buffer))
114 CRASH();
115 CryptReleaseContext(hCryptProv, 0);
116#else
117#error "This configuration doesn't have a strong source of randomness."
118// WARNING: When adding new sources of OS randomness, the randomness must
119// be of cryptographic quality!
120#endif
121}
122
123}
124