bitcoin/src/randomenv.cpp

// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2019 The Bitcoin Core developers
// 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 <util/time.h> // for GetTime()
#ifdef WIN32
#include <compat.h> // for Windows API
#endif

#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/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 {

void RandAddSeedPerfmon(CSHA512& hasher)
{
#ifdef WIN32
    // Don't need this on Linux, OpenSSL automatically uses /dev/urandom
    // Seed with the entire set of perfmon data

    // This can take up to 2 seconds, so only do it every 10 minutes
    static int64_t nLastPerfmon;
    if (GetTime() < nLastPerfmon + 10 * 60)
        return;
    nLastPerfmon = GetTime();

    std::vector<unsigned char> vData(250000, 0);
    long ret = 0;
    unsigned long nSize = 0;
    const size_t nMaxSize = 10000000; // Bail out at more than 10MB of performance data
    while (true) {
        nSize = vData.size();
        ret = RegQueryValueExA(HKEY_PERFORMANCE_DATA, "Global", nullptr, nullptr, vData.data(), &nSize);
        if (ret != ERROR_MORE_DATA || vData.size() >= nMaxSize)
            break;
        vData.resize(std::max((vData.size() * 3) / 2, nMaxSize)); // Grow size of buffer exponentially
    }
    RegCloseKey(HKEY_PERFORMANCE_DATA);
    if (ret == ERROR_SUCCESS) {
        hasher.Write(vData.data(), nSize);
        memory_cleanse(vData.data(), nSize);
    } else {
        // Performance data is only a best-effort attempt at improving the
        // situation when the OS randomness (and other sources) aren't
        // adequate. As a result, failure to read it is isn't considered critical,
        // so we don't call RandFailure().
        // TODO: Add logging when the logger is made functional before global
        // constructors have been invoked.
    }
#endif
}

/** Helper to easily feed data into a CSHA512.
 *
 * Note that this does not serialize the passed object (like stream.h's << operators do).
 * Its raw memory representation is used directly.
 */
template<typename T>
CSHA512& operator<<(CSHA512& hasher, const T& data) {
    static_assert(!std::is_same<typename std::decay<T>::type, char*>::value, "Calling operator<<(CSHA512, char*) is probably not what you want");
    static_assert(!std::is_same<typename std::decay<T>::type, unsigned char*>::value, "Calling operator<<(CSHA512, unsigned char*) is probably not what you want");
    static_assert(!std::is_same<typename std::decay<T>::type, const char*>::value, "Calling operator<<(CSHA512, const char*) is probably not what you want");
    static_assert(!std::is_same<typename std::decay<T>::type, const unsigned char*>::value, "Calling operator<<(CSHA512, const unsigned char*) is probably not what you want");
    hasher.Write((const unsigned char*)&data, sizeof(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)
{
    RandAddSeedPerfmon(hasher);

    // Various clocks
#ifdef WIN32
    FILETIME ftime;
    GetSystemTimeAsFileTime(&ftime);
    hasher << ftime;
#else
#  ifndef __MACH__
    // On non-MacOS systems, use various clock_gettime() calls.
    struct timespec ts = {};
#    ifdef CLOCK_MONOTONIC
    clock_gettime(CLOCK_MONOTONIC, &ts);
    hasher << ts;
#    endif
#    ifdef CLOCK_REALTIME
    clock_gettime(CLOCK_REALTIME, &ts);
    hasher << ts;
#    endif
#    ifdef CLOCK_BOOTTIME
    clock_gettime(CLOCK_BOOTTIME, &ts);
    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 = {};
    if (host_get_clock_service(mach_host_self(), CALENDAR_CLOCK, &cclock) == KERN_SUCCESS && clock_get_time(cclock, &mts) == KERN_SUCCESS) {
        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 = {};
    gettimeofday(&tv, nullptr);
    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() << getppid() << getsid(0) << getpgid(0) << getuid() << geteuid() << getgid() << getegid();
#endif
    hasher << std::this_thread::get_id();
}