/src/botan/src/lib/rng/processor_rng/processor_rng.cpp
Line | Count | Source (jump to first uncovered line) |
1 | | /* |
2 | | * (C) 2016,2019,2020 Jack Lloyd |
3 | | * |
4 | | * Botan is released under the Simplified BSD License (see license.txt) |
5 | | */ |
6 | | |
7 | | #include <botan/processor_rng.h> |
8 | | #include <botan/internal/loadstor.h> |
9 | | #include <botan/internal/cpuid.h> |
10 | | |
11 | | #if defined(BOTAN_TARGET_CPU_IS_X86_FAMILY) && !defined(BOTAN_USE_GCC_INLINE_ASM) |
12 | | #include <immintrin.h> |
13 | | #endif |
14 | | |
15 | | namespace Botan { |
16 | | |
17 | | namespace { |
18 | | |
19 | | #if defined(BOTAN_TARGET_CPU_IS_X86_FAMILY) |
20 | | /* |
21 | | * According to Intel, RDRAND is guaranteed to generate a random |
22 | | * number within 10 retries on a working CPU |
23 | | */ |
24 | | const size_t HWRNG_RETRIES = 10; |
25 | | |
26 | | #else |
27 | | /* |
28 | | * Lacking specific guidance we give the CPU quite a bit of leeway |
29 | | */ |
30 | | const size_t HWRNG_RETRIES = 512; |
31 | | #endif |
32 | | |
33 | | #if defined(BOTAN_TARGET_ARCH_IS_X86_32) |
34 | | typedef uint32_t hwrng_output; |
35 | | #else |
36 | | typedef uint64_t hwrng_output; |
37 | | #endif |
38 | | |
39 | | hwrng_output read_hwrng(bool& success) |
40 | 0 | { |
41 | 0 | hwrng_output output = 0; |
42 | 0 | success = false; |
43 | |
|
44 | 0 | #if defined(BOTAN_TARGET_CPU_IS_X86_FAMILY) |
45 | 0 | int cf = 0; |
46 | 0 | #if defined(BOTAN_USE_GCC_INLINE_ASM) |
47 | | // same asm seq works for 32 and 64 bit |
48 | 0 | asm volatile("rdrand %0; adcl $0,%1" : |
49 | 0 | "=r" (output), "=r" (cf) : "0" (output), "1" (cf) : "cc"); |
50 | | #elif defined(BOTAN_TARGET_ARCH_IS_X86_32) |
51 | | cf = _rdrand32_step(&output); |
52 | | #else |
53 | | cf = _rdrand64_step(&output); |
54 | | #endif |
55 | 0 | success = (1 == cf); |
56 | |
|
57 | | #elif defined(BOTAN_TARGET_CPU_IS_PPC_FAMILY) |
58 | | |
59 | | /* |
60 | | DARN indicates error by returning 0xFF..FF, ie is biased. Which is crazy. |
61 | | Avoid the bias by invoking it twice and, assuming both succeed, returning the |
62 | | XOR of the two results, which should unbias the output. |
63 | | */ |
64 | | uint64_t output2 = 0; |
65 | | // DARN codes are 0: 32-bit conditioned, 1: 64-bit conditioned, 2: 64-bit raw (ala RDSEED) |
66 | | asm volatile("darn %0, 1" : "=r" (output)); |
67 | | asm volatile("darn %0, 1" : "=r" (output2)); |
68 | | |
69 | | if((~output) != 0 && (~output2) != 0) |
70 | | { |
71 | | output ^= output2; |
72 | | success = true; |
73 | | } |
74 | | |
75 | | #endif |
76 | |
|
77 | 0 | if(success) |
78 | 0 | return output; |
79 | | |
80 | 0 | return 0; |
81 | 0 | } |
82 | | |
83 | | hwrng_output read_hwrng() |
84 | 0 | { |
85 | 0 | for(size_t i = 0; i < HWRNG_RETRIES; ++i) |
86 | 0 | { |
87 | 0 | bool success = false; |
88 | 0 | hwrng_output output = read_hwrng(success); |
89 | |
|
90 | 0 | if(success) |
91 | 0 | return output; |
92 | 0 | } |
93 | |
|
94 | 0 | throw PRNG_Unseeded("Processor RNG instruction failed to produce output within expected iterations"); |
95 | 0 | } |
96 | | |
97 | | } |
98 | | |
99 | | //static |
100 | | bool Processor_RNG::available() |
101 | 0 | { |
102 | 0 | #if defined(BOTAN_TARGET_CPU_IS_X86_FAMILY) |
103 | 0 | return CPUID::has_rdrand(); |
104 | | #elif defined(BOTAN_TARGET_CPU_IS_PPC_FAMILY) |
105 | | return CPUID::has_darn_rng(); |
106 | | #else |
107 | | return false; |
108 | | #endif |
109 | 0 | } |
110 | | |
111 | | std::string Processor_RNG::name() const |
112 | 0 | { |
113 | 0 | #if defined(BOTAN_TARGET_CPU_IS_X86_FAMILY) |
114 | 0 | return "rdrand"; |
115 | | #elif defined(BOTAN_TARGET_CPU_IS_PPC_FAMILY) |
116 | | return "darn"; |
117 | | #else |
118 | | return "hwrng"; |
119 | | #endif |
120 | 0 | } |
121 | | |
122 | | void Processor_RNG::randomize(uint8_t out[], size_t out_len) |
123 | 0 | { |
124 | 0 | while(out_len >= sizeof(hwrng_output)) |
125 | 0 | { |
126 | 0 | const hwrng_output r = read_hwrng(); |
127 | 0 | store_le(r, out); |
128 | 0 | out += sizeof(hwrng_output); |
129 | 0 | out_len -= sizeof(hwrng_output); |
130 | 0 | } |
131 | |
|
132 | 0 | if(out_len > 0) // at most sizeof(hwrng_output)-1 |
133 | 0 | { |
134 | 0 | const hwrng_output r = read_hwrng(); |
135 | 0 | for(size_t i = 0; i != out_len; ++i) |
136 | 0 | out[i] = get_byte(i, r); |
137 | 0 | } |
138 | 0 | } |
139 | | |
140 | | Processor_RNG::Processor_RNG() |
141 | 0 | { |
142 | 0 | if(!Processor_RNG::available()) |
143 | 0 | throw Invalid_State("Current CPU does not support RNG instruction"); |
144 | 0 | } |
145 | | |
146 | | void Processor_RNG::add_entropy(const uint8_t[], size_t) |
147 | 0 | { |
148 | | /* no way to add entropy */ |
149 | 0 | } |
150 | | |
151 | | size_t Processor_RNG::reseed(Entropy_Sources&, size_t, std::chrono::milliseconds) |
152 | 0 | { |
153 | | /* no way to add entropy */ |
154 | 0 | return 0; |
155 | 0 | } |
156 | | |
157 | | } |