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random: cleanup order, comments, static

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This commit is contained in:
Pieter Wuille
2024-03-11 14:10:44 -04:00
parent 8e31cf9c9b
commit 2c91330dd6
3 changed files with 109 additions and 83 deletions
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79
src/random.cpp
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@@ -45,13 +45,23 @@
#include <sys/auxv.h>
#endif
[[noreturn]] static void RandFailure()
namespace {
/* Number of random bytes returned by GetOSRand.
* When changing this constant make sure to change all call sites, and make
* sure that the underlying OS APIs for all platforms support the number.
* (many cap out at 256 bytes).
*/
static const int NUM_OS_RANDOM_BYTES = 32;
[[noreturn]] void RandFailure()
{
LogPrintf("Failed to read randomness, aborting\n");
std::abort();
}
static inline int64_t GetPerformanceCounter() noexcept
inline int64_t GetPerformanceCounter() noexcept
{
// Read the hardware time stamp counter when available.
// See https://en.wikipedia.org/wiki/Time_Stamp_Counter for more information.
@@ -72,10 +82,10 @@ static inline int64_t GetPerformanceCounter() noexcept
}
#ifdef HAVE_GETCPUID
static bool g_rdrand_supported = false;
static bool g_rdseed_supported = false;
static constexpr uint32_t CPUID_F1_ECX_RDRAND = 0x40000000;
static constexpr uint32_t CPUID_F7_EBX_RDSEED = 0x00040000;
bool g_rdrand_supported = false;
bool g_rdseed_supported = false;
constexpr uint32_t CPUID_F1_ECX_RDRAND = 0x40000000;
constexpr uint32_t CPUID_F7_EBX_RDSEED = 0x00040000;
#ifdef bit_RDRND
static_assert(CPUID_F1_ECX_RDRAND == bit_RDRND, "Unexpected value for bit_RDRND");
#endif
@@ -83,7 +93,7 @@ static_assert(CPUID_F1_ECX_RDRAND == bit_RDRND, "Unexpected value for bit_RDRND"
static_assert(CPUID_F7_EBX_RDSEED == bit_RDSEED, "Unexpected value for bit_RDSEED");
#endif
static void InitHardwareRand()
void InitHardwareRand()
{
uint32_t eax, ebx, ecx, edx;
GetCPUID(1, 0, eax, ebx, ecx, edx);
@@ -96,7 +106,7 @@ static void InitHardwareRand()
}
}
static void ReportHardwareRand()
void ReportHardwareRand()
{
// This must be done in a separate function, as InitHardwareRand() may be indirectly called
// from global constructors, before logging is initialized.
@@ -112,7 +122,7 @@ static void ReportHardwareRand()
*
* Must only be called when RdRand is supported.
*/
static uint64_t GetRdRand() noexcept
uint64_t GetRdRand() noexcept
{
// RdRand may very rarely fail. Invoke it up to 10 times in a loop to reduce this risk.
#ifdef __i386__
@@ -147,7 +157,7 @@ static uint64_t GetRdRand() noexcept
*
* Must only be called when RdSeed is supported.
*/
static uint64_t GetRdSeed() noexcept
uint64_t GetRdSeed() noexcept
{
// RdSeed may fail when the HW RNG is overloaded. Loop indefinitely until enough entropy is gathered,
// but pause after every failure.
@@ -181,16 +191,16 @@ static uint64_t GetRdSeed() noexcept
#elif defined(__aarch64__) && defined(HWCAP2_RNG)
static bool g_rndr_supported = false;
bool g_rndr_supported = false;
static void InitHardwareRand()
void InitHardwareRand()
{
if (getauxval(AT_HWCAP2) & HWCAP2_RNG) {
g_rndr_supported = true;
}
}
static void ReportHardwareRand()
void ReportHardwareRand()
{
// This must be done in a separate function, as InitHardwareRand() may be indirectly called
// from global constructors, before logging is initialized.
@@ -203,7 +213,7 @@ static void ReportHardwareRand()
*
* Must only be called when RNDR is supported.
*/
static uint64_t GetRNDR() noexcept
uint64_t GetRNDR() noexcept
{
uint8_t ok;
uint64_t r1;
@@ -221,7 +231,7 @@ static uint64_t GetRNDR() noexcept
*
* Must only be called when RNDRRS is supported.
*/
static uint64_t GetRNDRRS() noexcept
uint64_t GetRNDRRS() noexcept
{
uint8_t ok;
uint64_t r1;
@@ -241,12 +251,12 @@ static uint64_t GetRNDRRS() noexcept
* Slower sources should probably be invoked separately, and/or only from
* RandAddPeriodic (which is called once a minute).
*/
static void InitHardwareRand() {}
static void ReportHardwareRand() {}
void InitHardwareRand() {}
void ReportHardwareRand() {}
#endif
/** Add 64 bits of entropy gathered from hardware to hasher. Do nothing if not supported. */
static void SeedHardwareFast(CSHA512& hasher) noexcept {
void SeedHardwareFast(CSHA512& hasher) noexcept {
#if defined(__x86_64__) || defined(__amd64__) || defined(__i386__)
if (g_rdrand_supported) {
uint64_t out = GetRdRand();
@@ -263,7 +273,7 @@ static void SeedHardwareFast(CSHA512& hasher) noexcept {
}
/** Add 256 bits of entropy gathered from hardware to hasher. Do nothing if not supported. */
static void SeedHardwareSlow(CSHA512& hasher) noexcept {
void SeedHardwareSlow(CSHA512& hasher) noexcept {
#if defined(__x86_64__) || defined(__amd64__) || defined(__i386__)
// When we want 256 bits of entropy, prefer RdSeed over RdRand, as it's
// guaranteed to produce independent randomness on every call.
@@ -296,7 +306,7 @@ static void SeedHardwareSlow(CSHA512& hasher) noexcept {
}
/** Use repeated SHA512 to strengthen the randomness in seed32, and feed into hasher. */
static void Strengthen(const unsigned char (&seed)[32], SteadyClock::duration dur, CSHA512& hasher) noexcept
void Strengthen(const unsigned char (&seed)[32], SteadyClock::duration dur, CSHA512& hasher) noexcept
{
CSHA512 inner_hasher;
inner_hasher.Write(seed, sizeof(seed));
@@ -327,7 +337,7 @@ static void Strengthen(const unsigned char (&seed)[32], SteadyClock::duration du
/** Fallback: get 32 bytes of system entropy from /dev/urandom. The most
* compatible way to get cryptographic randomness on UNIX-ish platforms.
*/
[[maybe_unused]] static void GetDevURandom(unsigned char *ent32)
[[maybe_unused]] void GetDevURandom(unsigned char *ent32)
{
int f = open("/dev/urandom", O_RDONLY);
if (f == -1) {
@@ -402,8 +412,6 @@ void GetOSRand(unsigned char *ent32)
#endif
}
namespace {
class RNGState {
Mutex m_mutex;
/* The RNG state consists of 256 bits of entropy, taken from the output of
@@ -521,20 +529,19 @@ RNGState& GetRNGState() noexcept
static std::vector<RNGState, secure_allocator<RNGState>> g_rng(1);
return g_rng[0];
}
}
/* A note on the use of noexcept in the seeding functions below:
*
* None of the RNG code should ever throw any exception.
*/
static void SeedTimestamp(CSHA512& hasher) noexcept
void SeedTimestamp(CSHA512& hasher) noexcept
{
int64_t perfcounter = GetPerformanceCounter();
hasher.Write((const unsigned char*)&perfcounter, sizeof(perfcounter));
}
static void SeedFast(CSHA512& hasher) noexcept
void SeedFast(CSHA512& hasher) noexcept
{
unsigned char buffer[32];
@@ -549,7 +556,7 @@ static void SeedFast(CSHA512& hasher) noexcept
SeedTimestamp(hasher);
}
static void SeedSlow(CSHA512& hasher, RNGState& rng) noexcept
void SeedSlow(CSHA512& hasher, RNGState& rng) noexcept
{
unsigned char buffer[32];
@@ -571,7 +578,7 @@ static void SeedSlow(CSHA512& hasher, RNGState& rng) noexcept
}
/** Extract entropy from rng, strengthen it, and feed it into hasher. */
static void SeedStrengthen(CSHA512& hasher, RNGState& rng, SteadyClock::duration dur) noexcept
void SeedStrengthen(CSHA512& hasher, RNGState& rng, SteadyClock::duration dur) noexcept
{
// Generate 32 bytes of entropy from the RNG, and a copy of the entropy already in hasher.
// Never use the deterministic PRNG for this, as the result is only used internally.
@@ -581,7 +588,7 @@ static void SeedStrengthen(CSHA512& hasher, RNGState& rng, SteadyClock::duration
Strengthen(strengthen_seed, dur, hasher);
}
static void SeedPeriodic(CSHA512& hasher, RNGState& rng) noexcept
void SeedPeriodic(CSHA512& hasher, RNGState& rng) noexcept
{
// Everything that the 'fast' seeder includes
SeedFast(hasher);
@@ -601,7 +608,7 @@ static void SeedPeriodic(CSHA512& hasher, RNGState& rng) noexcept
SeedStrengthen(hasher, rng, 10ms);
}
static void SeedStartup(CSHA512& hasher, RNGState& rng) noexcept
void SeedStartup(CSHA512& hasher, RNGState& rng) noexcept
{
// Gather 256 bits of hardware randomness, if available
SeedHardwareSlow(hasher);
@@ -627,7 +634,7 @@ enum class RNGLevel {
PERIODIC, //!< Called by RandAddPeriodic()
};
static void ProcRand(unsigned char* out, int num, RNGLevel level, bool always_use_real_rng) noexcept
void ProcRand(unsigned char* out, int num, RNGLevel level, bool always_use_real_rng) noexcept
{
// Make sure the RNG is initialized first (as all Seed* function possibly need hwrand to be available).
RNGState& rng = GetRNGState();
@@ -656,6 +663,9 @@ static void ProcRand(unsigned char* out, int num, RNGLevel level, bool always_us
}
}
} // namespace
/** Internal function to set g_determinstic_rng. Only accessed from tests. */
void MakeRandDeterministicDANGEROUS(const uint256& seed) noexcept
{
@@ -679,13 +689,6 @@ void RandAddPeriodic() noexcept
void RandAddEvent(const uint32_t event_info) noexcept { GetRNGState().AddEvent(event_info); }
uint256 GetRandHash() noexcept
{
uint256 hash;
GetRandBytes(hash);
return hash;
}
void FastRandomContext::RandomSeed() noexcept
{
uint256 seed = GetRandHash();