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Gather additional entropy from the environment
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This based on code by Gregory Maxwell.

Cherry-picked from: 2554c1b
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@sipa @xanimo
sipa authored and xanimo committed May 7, 2024
1 parent 194a732 commit 625feee
Showing 1 changed file with 184 additions and 10 deletions.
194 changes: 184 additions & 10 deletions src/randomenv.cpp
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Expand Up @@ -3,8 +3,13 @@
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.

#if defined(HAVE_CONFIG_H)
#include <config/bitcoin-config.h>
#endif

#include <randomenv.h>

#include <clientversion.h>
#include <crypto/sha512.h>
#include <support/cleanse.h>
#include <utiltime.h> // for GetTime()
Expand All @@ -14,21 +19,34 @@

#include <algorithm>
#include <chrono>
#include <climits>
#include <thread>
#include <vector>

#include <stdint.h>
#include <string.h>
#ifndef WIN32
#include <sys/types.h> // must go before a number of other headers
#include <fcntl.h>
#include <netinet/in.h>
#include <sys/resource.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/utsname.h>
#include <unistd.h>
#endif
#ifdef __MACH__
#include <mach/clock.h>
#include <mach/mach.h>
#include <mach/mach_time.h>
#endif
#if HAVE_DECL_GETIFADDRS
#include <ifaddrs.h>
#endif

//! Necessary on some platforms
extern char** environ;

namespace {

Expand Down Expand Up @@ -85,6 +103,53 @@ CSHA512& operator<<(CSHA512& hasher, const T& data) {
return hasher;
}

#ifndef WIN32
void AddSockaddr(CSHA512& hasher, const struct sockaddr *addr)
{
if (addr == nullptr) return;
switch (addr->sa_family) {
case AF_INET:
hasher.Write((const unsigned char*)addr, sizeof(sockaddr_in));
break;
case AF_INET6:
hasher.Write((const unsigned char*)addr, sizeof(sockaddr_in6));
break;
default:
hasher.Write((const unsigned char*)&addr->sa_family, sizeof(addr->sa_family));
}
}

void AddFile(CSHA512& hasher, const char *path)
{
struct stat sb = {};
int f = open(path, O_RDONLY);
size_t total = 0;
if (f != -1) {
unsigned char fbuf[4096];
int n;
hasher.Write((const unsigned char*)&f, sizeof(f));
if (fstat(f, &sb) == 0) hasher << sb;
do {
n = read(f, fbuf, sizeof(fbuf));
if (n > 0) hasher.Write(fbuf, n);
total += n;
/* not bothering with EINTR handling. */
} while (n == sizeof(fbuf) && total < 1048576); // Read only the first 1 Mbyte
close(f);
}
}

void AddPath(CSHA512& hasher, const char *path)
{
struct stat sb = {};
if (stat(path, &sb) == 0) {
hasher.Write((const unsigned char*)path, strlen(path) + 1);
hasher << sb;
}
}
#endif


} // namespace

void RandAddDynamicEnv(CSHA512& hasher)
Expand All @@ -99,48 +164,157 @@ void RandAddDynamicEnv(CSHA512& hasher)
#else
# ifndef __MACH__
// On non-MacOS systems, use various clock_gettime() calls.
struct timespec ts;
struct timespec ts = {};
# ifdef CLOCK_MONOTONIC
clock_gettime(CLOCK_MONOTONIC, &ts);
hasher << ts.tv_sec << ts.tv_nsec;
hasher << ts;
# endif
# ifdef CLOCK_REALTIME
clock_gettime(CLOCK_REALTIME, &ts);
hasher << ts.tv_sec << ts.tv_nsec;
hasher << ts;
# endif
# ifdef CLOCK_BOOTTIME
clock_gettime(CLOCK_BOOTTIME, &ts);
hasher << ts.tv_sec << ts.tv_nsec;
hasher << ts;
# endif
# else
// On MacOS use mach_absolute_time (number of CPU ticks since boot) as a replacement for CLOCK_MONOTONIC,
// and clock_get_time for CALENDAR_CLOCK as a replacement for CLOCK_REALTIME.
hasher << mach_absolute_time();
// From https://gist.github.com/jbenet/1087739
clock_serv_t cclock;
mach_timespec_t mts;
mach_timespec_t mts = {};
if (host_get_clock_service(mach_host_self(), CALENDAR_CLOCK, &cclock) == KERN_SUCCESS && clock_get_time(cclock, &mts) == KERN_SUCCESS) {
hasher << mts.tv_sec << mts.tv_nsec;
hasher << mts;
mach_port_deallocate(mach_task_self(), cclock);
}
# endif
// gettimeofday is available on all UNIX systems, but only has microsecond precision.
struct timeval tv;
struct timeval tv = {};
gettimeofday(&tv, nullptr);
hasher << tv.tv_sec << tv.tv_usec;
hasher << tv;
#endif
// Probably redundant, but also use all the clocks C++11 provides:
hasher << std::chrono::system_clock::now().time_since_epoch().count();
hasher << std::chrono::steady_clock::now().time_since_epoch().count();
hasher << std::chrono::high_resolution_clock::now().time_since_epoch().count();

#ifndef WIN32
// Current resource usage.
struct rusage usage = {};
if (getrusage(RUSAGE_SELF, &usage) == 0) hasher << usage;
#endif

#ifdef __linux__
AddFile(hasher, "/proc/diskstats");
AddFile(hasher, "/proc/vmstat");
AddFile(hasher, "/proc/schedstat");
AddFile(hasher, "/proc/zoneinfo");
AddFile(hasher, "/proc/meminfo");
AddFile(hasher, "/proc/softirqs");
AddFile(hasher, "/proc/stat");
AddFile(hasher, "/proc/self/schedstat");
AddFile(hasher, "/proc/self/status");
#endif

// Stack and heap location
void* addr = malloc(4097);
hasher << &addr << addr;
free(addr);
}

void RandAddStaticEnv(CSHA512& hasher)
{
// Some compile-time static properties
hasher << (CHAR_MIN < 0) << sizeof(void*) << sizeof(long) << sizeof(int);
#if defined(__GNUC__) && defined(__GNUC_MINOR__) && defined(__GNUC_PATCHLEVEL__)
hasher << __GNUC__ << __GNUC_MINOR__ << __GNUC_PATCHLEVEL__;
#endif
#ifdef _MSC_VER
hasher << _MSC_VER;
#endif
hasher << __cplusplus;
#ifdef _XOPEN_VERSION
hasher << _XOPEN_VERSION;
#endif
#ifdef __VERSION__
const char* COMPILER_VERSION = __VERSION__;
hasher.Write((const unsigned char*)COMPILER_VERSION, strlen(COMPILER_VERSION) + 1);
#endif

// Bitcoin client version
hasher << CLIENT_VERSION;

// Memory locations
hasher << &hasher << &RandAddStaticEnv << &malloc << &errno << &environ;

// Hostname
char hname[256];
if (gethostname(hname, 256) == 0) {
hasher.Write((const unsigned char*)hname, strnlen(hname, 256));
}

#if HAVE_DECL_GETIFADDRS
// Network interfaces
struct ifaddrs *ifad = NULL;
getifaddrs(&ifad);
struct ifaddrs *ifit = ifad;
while (ifit != NULL) {
hasher.Write((const unsigned char*)&ifit, sizeof(ifit));
hasher.Write((const unsigned char*)ifit->ifa_name, strlen(ifit->ifa_name) + 1);
hasher.Write((const unsigned char*)&ifit->ifa_flags, sizeof(ifit->ifa_flags));
AddSockaddr(hasher, ifit->ifa_addr);
AddSockaddr(hasher, ifit->ifa_netmask);
AddSockaddr(hasher, ifit->ifa_dstaddr);
ifit = ifit->ifa_next;
}
freeifaddrs(ifad);
#endif

#ifndef WIN32
// UNIX kernel information
struct utsname name;
if (uname(&name) != -1) {
hasher.Write((const unsigned char*)&name.sysname, strlen(name.sysname) + 1);
hasher.Write((const unsigned char*)&name.nodename, strlen(name.nodename) + 1);
hasher.Write((const unsigned char*)&name.release, strlen(name.release) + 1);
hasher.Write((const unsigned char*)&name.version, strlen(name.version) + 1);
hasher.Write((const unsigned char*)&name.machine, strlen(name.machine) + 1);
}

/* Path and filesystem provided data */
AddPath(hasher, "/");
AddPath(hasher, ".");
AddPath(hasher, "/tmp");
AddPath(hasher, "/home");
AddPath(hasher, "/proc");
#ifdef __linux__
AddFile(hasher, "/proc/cmdline");
AddFile(hasher, "/proc/cpuinfo");
AddFile(hasher, "/proc/version");
#endif
AddFile(hasher, "/etc/passwd");
AddFile(hasher, "/etc/group");
AddFile(hasher, "/etc/hosts");
AddFile(hasher, "/etc/resolv.conf");
AddFile(hasher, "/etc/timezone");
AddFile(hasher, "/etc/localtime");

/* TODO: sysctl's for OSX to fetch information not available from /proc */
#endif

// Env variables
if (environ) {
for (size_t i = 0; environ[i]; ++i) {
hasher.Write((const unsigned char*)environ[i], strlen(environ[i]));
}
}

// Process, thread, user, session, group, ... ids.
#ifdef WIN32
hasher << GetCurrentProcessId() << GetCurrentThreadId();
#else
hasher << getpid();
hasher << getpid() << getppid() << getsid(0) << getpgid(0) << getuid() << geteuid() << getgid() << getegid();
#endif
hasher << std::this_thread::get_id();
}

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