1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
|
/*
* System RNG
* (C) 2014,2015 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#include <botan/system_rng.h>
#if defined(BOTAN_TARGET_OS_HAS_CRYPTGENRANDOM)
#include <windows.h>
#define NOMINMAX 1
#include <wincrypt.h>
#else
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#endif
namespace Botan {
namespace {
class System_RNG_Impl final : public RandomNumberGenerator
{
public:
System_RNG_Impl();
~System_RNG_Impl();
bool is_seeded() const override { return true; }
void clear() override {}
void randomize(uint8_t out[], size_t len) override;
void add_entropy(const uint8_t in[], size_t length) override;
std::string name() const override;
private:
#if defined(BOTAN_TARGET_OS_HAS_CRYPTGENRANDOM)
HCRYPTPROV m_prov;
#else
int m_fd;
#endif
};
std::string System_RNG_Impl::name() const
{
#if defined(BOTAN_TARGET_OS_HAS_CRYPTGENRANDOM)
return "cryptoapi";
#else
return BOTAN_SYSTEM_RNG_DEVICE;
#endif
}
System_RNG_Impl::System_RNG_Impl()
{
#if defined(BOTAN_TARGET_OS_HAS_CRYPTGENRANDOM)
if(!CryptAcquireContext(&m_prov, 0, 0, BOTAN_SYSTEM_RNG_CRYPTOAPI_PROV_TYPE, CRYPT_VERIFYCONTEXT))
throw Exception("System_RNG failed to acquire crypto provider");
#else
#ifndef O_NOCTTY
#define O_NOCTTY 0
#endif
m_fd = ::open(BOTAN_SYSTEM_RNG_DEVICE, O_RDWR | O_NOCTTY);
// Cannot open in read-write mode. Fall back to read-only
// Calls to add_entropy will fail, but randomize will work
if(m_fd < 0)
m_fd = ::open(BOTAN_SYSTEM_RNG_DEVICE, O_RDONLY | O_NOCTTY);
if(m_fd < 0)
throw Exception("System_RNG failed to open RNG device");
#endif
}
System_RNG_Impl::~System_RNG_Impl()
{
#if defined(BOTAN_TARGET_OS_HAS_CRYPTGENRANDOM)
::CryptReleaseContext(m_prov, 0);
#else
::close(m_fd);
m_fd = -1;
#endif
}
void System_RNG_Impl::add_entropy(const uint8_t input[], size_t len)
{
#if defined(BOTAN_TARGET_OS_HAS_CRYPTGENRANDOM)
/*
There is no explicit ConsumeRandom, but all values provided in
the call are incorporated into the state.
TODO: figure out a way to avoid this copy. Byte at a time updating
seems worse than the allocation.
for(size_t i = 0; i != len; ++i)
{
uint8_t b = input[i];
::CryptGenRandom(m_prov, 1, &b);
}
*/
if(len > 0)
{
secure_vector<uint8_t> buf(input, input + len);
::CryptGenRandom(m_prov, static_cast<DWORD>(buf.size()), buf.data());
}
#else
while(len)
{
ssize_t got = ::write(m_fd, input, len);
if(got < 0)
{
if(errno == EINTR)
continue;
/*
* This is seen on OS X CI, despite the fact that the man page
* for Darwin urandom explicitly states that writing to it is
* supported, and write(2) does not document EPERM at all.
* But in any case EPERM seems indicative of a policy decision
* by the OS or sysadmin that additional entropy is not wanted
* in the system pool, so we accept that and return here,
* since there is no corrective action possible.
*
* In Linux EBADF or EPERM is returned if m_fd is not opened for
* writing.
*/
if(errno == EPERM || errno == EBADF)
return;
// maybe just ignore any failure here and return?
throw Exception("System_RNG write failed error " + std::to_string(errno));
}
input += got;
len -= got;
}
#endif
}
void System_RNG_Impl::randomize(uint8_t buf[], size_t len)
{
#if defined(BOTAN_TARGET_OS_HAS_CRYPTGENRANDOM)
::CryptGenRandom(m_prov, static_cast<DWORD>(len), buf);
#else
while(len)
{
ssize_t got = ::read(m_fd, buf, len);
if(got < 0)
{
if(errno == EINTR)
continue;
throw Exception("System_RNG read failed error " + std::to_string(errno));
}
if(got == 0)
throw Exception("System_RNG EOF on device"); // ?!?
buf += got;
len -= got;
}
#endif
}
}
RandomNumberGenerator& system_rng()
{
static System_RNG_Impl g_system_rng;
return g_system_rng;
}
}
|
