Defcon/hook_lib/asmjit/core/virtmem.cpp

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2023-11-26 08:54:06 -05:00
// This file is part of AsmJit project <https://asmjit.com>
//
// See asmjit.h or LICENSE.md for license and copyright information
// SPDX-License-Identifier: Zlib
#include "../core/api-build_p.h"
#ifndef ASMJIT_NO_JIT
#include "../core/osutils.h"
#include "../core/string.h"
#include "../core/support.h"
#include "../core/virtmem.h"
#if !defined(_WIN32)
#include <errno.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
// Linux has a `memfd_create` syscall that we would like to use, if available.
#if defined(__linux__)
#include <sys/syscall.h>
#endif
// Apple recently introduced MAP_JIT flag, which we want to use.
#if defined(__APPLE__)
#include <pthread.h>
#include <TargetConditionals.h>
#if TARGET_OS_OSX
#include <sys/utsname.h>
#include <libkern/OSCacheControl.h> // sys_icache_invalidate().
#endif
// Older SDK doesn't define `MAP_JIT`.
#ifndef MAP_JIT
#define MAP_JIT 0x800
#endif
#endif
// BSD/MAC: `MAP_ANONYMOUS` is not defined, `MAP_ANON` is.
#if !defined(MAP_ANONYMOUS)
#define MAP_ANONYMOUS MAP_ANON
#endif
#endif
#include <atomic>
#if defined(__APPLE__) || defined(__BIONIC__)
#define ASMJIT_VM_SHM_DETECT 0
#else
#define ASMJIT_VM_SHM_DETECT 1
#endif
// Android NDK doesn't provide `shm_open()` and `shm_unlink()`.
#if !defined(_WIN32) && !defined(__BIONIC__)
#define ASMJIT_HAS_SHM_OPEN_AND_UNLINK
#endif
#if defined(__APPLE__) && TARGET_OS_OSX && ASMJIT_ARCH_ARM >= 64
#define ASMJIT_HAS_PTHREAD_JIT_WRITE_PROTECT_NP
#endif
ASMJIT_BEGIN_SUB_NAMESPACE(VirtMem)
// Virtual Memory Utilities
// ========================
static const MemoryFlags dualMappingFilter[2] = {
MemoryFlags::kAccessWrite | MemoryFlags::kMMapMaxAccessWrite,
MemoryFlags::kAccessExecute | MemoryFlags::kMMapMaxAccessExecute
};
// Virtual Memory [Windows]
// ========================
#if defined(_WIN32)
struct ScopedHandle {
inline ScopedHandle() noexcept
: value(nullptr) {}
inline ~ScopedHandle() noexcept {
if (value != nullptr)
::CloseHandle(value);
}
HANDLE value;
};
static void getVMInfo(Info& vmInfo) noexcept {
SYSTEM_INFO systemInfo;
::GetSystemInfo(&systemInfo);
vmInfo.pageSize = Support::alignUpPowerOf2<uint32_t>(systemInfo.dwPageSize);
vmInfo.pageGranularity = systemInfo.dwAllocationGranularity;
}
// Returns windows-specific protectFlags from \ref MemoryFlags.
static DWORD protectFlagsFromMemoryFlags(MemoryFlags memoryFlags) noexcept {
DWORD protectFlags;
// READ|WRITE|EXECUTE.
if (Support::test(memoryFlags, MemoryFlags::kAccessExecute))
protectFlags = Support::test(memoryFlags, MemoryFlags::kAccessWrite) ? PAGE_EXECUTE_READWRITE : PAGE_EXECUTE_READ;
else if (Support::test(memoryFlags, MemoryFlags::kAccessRW))
protectFlags = Support::test(memoryFlags, MemoryFlags::kAccessWrite) ? PAGE_READWRITE : PAGE_READONLY;
else
protectFlags = PAGE_NOACCESS;
// Any other flags to consider?
return protectFlags;
}
static DWORD desiredAccessFromMemoryFlags(MemoryFlags memoryFlags) noexcept {
DWORD access = Support::test(memoryFlags, MemoryFlags::kAccessWrite) ? FILE_MAP_WRITE : FILE_MAP_READ;
if (Support::test(memoryFlags, MemoryFlags::kAccessExecute))
access |= FILE_MAP_EXECUTE;
return access;
}
static HardenedRuntimeFlags getHardenedRuntimeFlags() noexcept {
return HardenedRuntimeFlags::kNone;
}
Error alloc(void** p, size_t size, MemoryFlags memoryFlags) noexcept {
*p = nullptr;
if (size == 0)
return DebugUtils::errored(kErrorInvalidArgument);
DWORD protectFlags = protectFlagsFromMemoryFlags(memoryFlags);
void* result = ::VirtualAlloc(nullptr, size, MEM_COMMIT | MEM_RESERVE, protectFlags);
if (!result)
return DebugUtils::errored(kErrorOutOfMemory);
*p = result;
return kErrorOk;
}
Error release(void* p, size_t size) noexcept {
DebugUtils::unused(size);
if (ASMJIT_UNLIKELY(!::VirtualFree(p, 0, MEM_RELEASE)))
return DebugUtils::errored(kErrorInvalidArgument);
return kErrorOk;
}
Error protect(void* p, size_t size, MemoryFlags memoryFlags) noexcept {
DWORD protectFlags = protectFlagsFromMemoryFlags(memoryFlags);
DWORD oldFlags;
if (::VirtualProtect(p, size, protectFlags, &oldFlags))
return kErrorOk;
return DebugUtils::errored(kErrorInvalidArgument);
}
Error allocDualMapping(DualMapping* dm, size_t size, MemoryFlags memoryFlags) noexcept {
dm->rx = nullptr;
dm->rw = nullptr;
if (size == 0)
return DebugUtils::errored(kErrorInvalidArgument);
ScopedHandle handle;
handle.value = ::CreateFileMappingW(
INVALID_HANDLE_VALUE,
nullptr,
PAGE_EXECUTE_READWRITE,
(DWORD)(uint64_t(size) >> 32),
(DWORD)(size & 0xFFFFFFFFu),
nullptr);
if (ASMJIT_UNLIKELY(!handle.value))
return DebugUtils::errored(kErrorOutOfMemory);
void* ptr[2];
for (uint32_t i = 0; i < 2; i++) {
MemoryFlags accessFlags = memoryFlags & ~dualMappingFilter[i];
DWORD desiredAccess = desiredAccessFromMemoryFlags(accessFlags);
ptr[i] = ::MapViewOfFile(handle.value, desiredAccess, 0, 0, size);
if (ptr[i] == nullptr) {
if (i == 0)
::UnmapViewOfFile(ptr[0]);
return DebugUtils::errored(kErrorOutOfMemory);
}
}
dm->rx = ptr[0];
dm->rw = ptr[1];
return kErrorOk;
}
Error releaseDualMapping(DualMapping* dm, size_t size) noexcept {
DebugUtils::unused(size);
bool failed = false;
if (!::UnmapViewOfFile(dm->rx))
failed = true;
if (dm->rx != dm->rw && !UnmapViewOfFile(dm->rw))
failed = true;
if (failed)
return DebugUtils::errored(kErrorInvalidArgument);
dm->rx = nullptr;
dm->rw = nullptr;
return kErrorOk;
}
#endif
// Virtual Memory [Posix]
// ======================
#if !defined(_WIN32)
static void getVMInfo(Info& vmInfo) noexcept {
uint32_t pageSize = uint32_t(::getpagesize());
vmInfo.pageSize = pageSize;
vmInfo.pageGranularity = Support::max<uint32_t>(pageSize, 65536);
}
#if !defined(SHM_ANON)
static const char* getTmpDir() noexcept {
const char* tmpDir = getenv("TMPDIR");
return tmpDir ? tmpDir : "/tmp";
}
#endif
// Translates libc errors specific to VirtualMemory mapping to `asmjit::Error`.
static Error asmjitErrorFromErrno(int e) noexcept {
switch (e) {
case EACCES:
case EAGAIN:
case ENODEV:
case EPERM:
return kErrorInvalidState;
case EFBIG:
case ENOMEM:
case EOVERFLOW:
return kErrorOutOfMemory;
case EMFILE:
case ENFILE:
return kErrorTooManyHandles;
default:
return kErrorInvalidArgument;
}
}
// Some operating systems don't allow /dev/shm to be executable. On Linux this happens when /dev/shm is mounted with
// 'noexec', which is enforced by systemd. Other operating systems like MacOS also restrict executable permissions
// regarding /dev/shm, so we use a runtime detection before attempting to allocate executable memory. Sometimes we
// don't need the detection as we know it would always result in `ShmStrategy::kTmpDir`.
enum class ShmStrategy : uint32_t {
kUnknown = 0,
kDevShm = 1,
kTmpDir = 2
};
class AnonymousMemory {
public:
enum FileType : uint32_t {
kFileTypeNone,
kFileTypeShm,
kFileTypeTmp
};
int _fd;
FileType _fileType;
StringTmp<128> _tmpName;
inline AnonymousMemory() noexcept
: _fd(-1),
_fileType(kFileTypeNone),
_tmpName() {}
inline ~AnonymousMemory() noexcept {
unlink();
close();
}
inline int fd() const noexcept { return _fd; }
Error open(bool preferTmpOverDevShm) noexcept {
#if defined(__linux__) && defined(__NR_memfd_create)
// Linux specific 'memfd_create' - if the syscall returns `ENOSYS` it means
// it's not available and we will never call it again (would be pointless).
// Zero initialized, if ever changed to '1' that would mean the syscall is not
// available and we must use `shm_open()` and `shm_unlink()`.
static volatile uint32_t memfd_create_not_supported;
if (!memfd_create_not_supported) {
_fd = (int)syscall(__NR_memfd_create, "vmem", 0);
if (ASMJIT_LIKELY(_fd >= 0))
return kErrorOk;
int e = errno;
if (e == ENOSYS)
memfd_create_not_supported = 1;
else
return DebugUtils::errored(asmjitErrorFromErrno(e));
}
#endif
#if defined(SHM_ANON)
// Originally FreeBSD extension, apparently works in other BSDs too.
DebugUtils::unused(preferTmpOverDevShm);
_fd = ::shm_open(SHM_ANON, O_RDWR | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR);
if (ASMJIT_LIKELY(_fd >= 0))
return kErrorOk;
else
return DebugUtils::errored(asmjitErrorFromErrno(errno));
#else
// POSIX API. We have to generate somehow a unique name. This is nothing cryptographic, just using a bit from
// the stack address to always have a different base for different threads (as threads have their own stack)
// and retries for avoiding collisions. We use `shm_open()` with flags that require creation of the file so we
// never open an existing shared memory.
static std::atomic<uint32_t> internalCounter;
const char* kShmFormat = "/shm-id-%016llX";
uint32_t kRetryCount = 100;
uint64_t bits = ((uintptr_t)(void*)this) & 0x55555555u;
for (uint32_t i = 0; i < kRetryCount; i++) {
bits -= uint64_t(OSUtils::getTickCount()) * 773703683;
bits = ((bits >> 14) ^ (bits << 6)) + uint64_t(++internalCounter) * 10619863;
bool useTmp = !ASMJIT_VM_SHM_DETECT || preferTmpOverDevShm;
if (useTmp) {
_tmpName.assign(getTmpDir());
_tmpName.appendFormat(kShmFormat, (unsigned long long)bits);
_fd = ::open(_tmpName.data(), O_RDWR | O_CREAT | O_EXCL, 0);
if (ASMJIT_LIKELY(_fd >= 0)) {
_fileType = kFileTypeTmp;
return kErrorOk;
}
}
#ifdef ASMJIT_HAS_SHM_OPEN_AND_UNLINK
else {
_tmpName.assignFormat(kShmFormat, (unsigned long long)bits);
_fd = ::shm_open(_tmpName.data(), O_RDWR | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR);
if (ASMJIT_LIKELY(_fd >= 0)) {
_fileType = kFileTypeShm;
return kErrorOk;
}
}
#endif
int e = errno;
if (e != EEXIST)
return DebugUtils::errored(asmjitErrorFromErrno(e));
}
return DebugUtils::errored(kErrorFailedToOpenAnonymousMemory);
#endif
}
void unlink() noexcept {
FileType type = _fileType;
_fileType = kFileTypeNone;
#ifdef ASMJIT_HAS_SHM_OPEN_AND_UNLINK
if (type == kFileTypeShm) {
::shm_unlink(_tmpName.data());
return;
}
#endif
if (type == kFileTypeTmp) {
::unlink(_tmpName.data());
return;
}
}
void close() noexcept {
if (_fd >= 0) {
::close(_fd);
_fd = -1;
}
}
Error allocate(size_t size) noexcept {
// TODO: Improve this by using `posix_fallocate()` when available.
if (ftruncate(_fd, off_t(size)) != 0)
return DebugUtils::errored(asmjitErrorFromErrno(errno));
return kErrorOk;
}
};
// Returns `mmap()` protection flags from \ref MemoryFlags.
static int mmProtFromMemoryFlags(MemoryFlags memoryFlags) noexcept {
int protection = 0;
if (Support::test(memoryFlags, MemoryFlags::kAccessRead)) protection |= PROT_READ;
if (Support::test(memoryFlags, MemoryFlags::kAccessWrite)) protection |= PROT_READ | PROT_WRITE;
if (Support::test(memoryFlags, MemoryFlags::kAccessExecute)) protection |= PROT_READ | PROT_EXEC;
return protection;
}
#if defined(__APPLE__) && TARGET_OS_OSX
static int getOSXVersion() noexcept {
// MAP_JIT flag required to run unsigned JIT code is only supported by kernel version 10.14+ (Mojave).
static std::atomic<int> globalVersion;
int ver = globalVersion.load();
if (!ver) {
struct utsname osname {};
uname(&osname);
ver = atoi(osname.release);
globalVersion.store(ver);
}
return ver;
}
#endif // __APPLE__ && TARGET_OS_OSX
// Detects whether the current process is hardened, which means that pages that have WRITE and EXECUTABLE flags
// cannot be normally allocated. On OSX + AArch64 such allocation requires MAP_JIT flag, other platforms don't
// support this combination.
static bool hasHardenedRuntime() noexcept {
#if TARGET_OS_OSX && ASMJIT_ARCH_ARM >= 64
// OSX on AArch64 has always hardened runtime enabled.
return true;
#else
static std::atomic<uint32_t> globalHardenedFlag;
enum HardenedFlag : uint32_t {
kHardenedFlagUnknown = 0,
kHardenedFlagDisabled = 1,
kHardenedFlagEnabled = 2
};
uint32_t flag = globalHardenedFlag.load();
if (flag == kHardenedFlagUnknown) {
uint32_t pageSize = uint32_t(::getpagesize());
void* ptr = mmap(nullptr, pageSize, PROT_WRITE | PROT_EXEC, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
if (ptr == MAP_FAILED) {
flag = kHardenedFlagEnabled;
}
else {
flag = kHardenedFlagDisabled;
munmap(ptr, pageSize);
}
globalHardenedFlag.store(flag);
}
return flag == kHardenedFlagEnabled;
#endif
}
// Detects whether MAP_JIT is available.
static inline bool hasMapJitSupport() noexcept {
#if defined(__APPLE__) && TARGET_OS_OSX && ASMJIT_ARCH_ARM >= 64
// OSX on AArch64 always uses hardened runtime + MAP_JIT:
// - https://developer.apple.com/documentation/apple_silicon/porting_just-in-time_compilers_to_apple_silicon
return true;
#elif defined(__APPLE__) && TARGET_OS_OSX
return getOSXVersion() >= 18;
#else
// MAP_JIT is not available (it's only available on OSX).
return false;
#endif
}
// Returns either MAP_JIT or 0 based on `flags` and the host operating system.
static inline int mmMapJitFromMemoryFlags(MemoryFlags memoryFlags) noexcept {
#if defined(__APPLE__)
// Always use MAP_JIT flag if user asked for it (could be used for testing on non-hardened processes) and detect
// whether it must be used when the process is actually hardened (in that case it doesn't make sense to rely on
// user `memoryFlags`).
bool useMapJit = Support::test(memoryFlags, MemoryFlags::kMMapEnableMapJit) || hasHardenedRuntime();
if (useMapJit)
return hasMapJitSupport() ? int(MAP_JIT) : 0;
else
return 0;
#else
DebugUtils::unused(memoryFlags);
return 0;
#endif
}
// Returns BSD-specific `PROT_MAX()` flags.
static inline int mmMaxProtFromMemoryFlags(MemoryFlags memoryFlags) noexcept {
#if defined(PROT_MAX)
static constexpr uint32_t kMaxProtShift = Support::ConstCTZ<uint32_t(MemoryFlags::kMMapMaxAccessRead)>::value;
if (Support::test(memoryFlags, MemoryFlags::kMMapMaxAccessReadWrite | MemoryFlags::kMMapMaxAccessExecute))
return PROT_MAX(mmProtFromMemoryFlags((MemoryFlags)(uint32_t(memoryFlags) >> kMaxProtShift)));
else
return 0;
#else
DebugUtils::unused(memoryFlags);
return 0;
#endif
}
#if ASMJIT_VM_SHM_DETECT
static Error detectShmStrategy(ShmStrategy* strategyOut) noexcept {
AnonymousMemory anonMem;
Info vmInfo = info();
ASMJIT_PROPAGATE(anonMem.open(false));
ASMJIT_PROPAGATE(anonMem.allocate(vmInfo.pageSize));
void* ptr = mmap(nullptr, vmInfo.pageSize, PROT_READ | PROT_EXEC, MAP_SHARED, anonMem.fd(), 0);
if (ptr == MAP_FAILED) {
int e = errno;
if (e == EINVAL) {
*strategyOut = ShmStrategy::kTmpDir;
return kErrorOk;
}
return DebugUtils::errored(asmjitErrorFromErrno(e));
}
else {
munmap(ptr, vmInfo.pageSize);
*strategyOut = ShmStrategy::kDevShm;
return kErrorOk;
}
}
#endif
static Error getShmStrategy(ShmStrategy* strategyOut) noexcept {
#if ASMJIT_VM_SHM_DETECT
// Initially don't assume anything. It has to be tested whether '/dev/shm' was mounted with 'noexec' flag or not.
static std::atomic<uint32_t> globalShmStrategy;
ShmStrategy strategy = static_cast<ShmStrategy>(globalShmStrategy.load());
if (strategy == ShmStrategy::kUnknown) {
ASMJIT_PROPAGATE(detectShmStrategy(&strategy));
globalShmStrategy.store(static_cast<uint32_t>(strategy));
}
*strategyOut = strategy;
return kErrorOk;
#else
*strategyOut = ShmStrategy::kTmpDir;
return kErrorOk;
#endif
}
static HardenedRuntimeFlags getHardenedRuntimeFlags() noexcept {
HardenedRuntimeFlags flags = HardenedRuntimeFlags::kNone;
if (hasHardenedRuntime())
flags |= HardenedRuntimeFlags::kEnabled;
if (hasMapJitSupport())
flags |= HardenedRuntimeFlags::kMapJit;
return flags;
}
Error alloc(void** p, size_t size, MemoryFlags memoryFlags) noexcept {
*p = nullptr;
if (size == 0)
return DebugUtils::errored(kErrorInvalidArgument);
int protection = mmProtFromMemoryFlags(memoryFlags) | mmMaxProtFromMemoryFlags(memoryFlags);
int mmFlags = MAP_PRIVATE | MAP_ANONYMOUS | mmMapJitFromMemoryFlags(memoryFlags);
void* ptr = mmap(nullptr, size, protection, mmFlags, -1, 0);
if (ptr == MAP_FAILED)
return DebugUtils::errored(kErrorOutOfMemory);
*p = ptr;
return kErrorOk;
}
Error release(void* p, size_t size) noexcept {
if (ASMJIT_UNLIKELY(munmap(p, size) != 0))
return DebugUtils::errored(kErrorInvalidArgument);
return kErrorOk;
}
Error protect(void* p, size_t size, MemoryFlags memoryFlags) noexcept {
int protection = mmProtFromMemoryFlags(memoryFlags);
if (mprotect(p, size, protection) == 0)
return kErrorOk;
return DebugUtils::errored(kErrorInvalidArgument);
}
Error allocDualMapping(DualMapping* dm, size_t size, MemoryFlags memoryFlags) noexcept {
dm->rx = nullptr;
dm->rw = nullptr;
if (off_t(size) <= 0)
return DebugUtils::errored(size == 0 ? kErrorInvalidArgument : kErrorTooLarge);
bool preferTmpOverDevShm = Support::test(memoryFlags, MemoryFlags::kMappingPreferTmp);
if (!preferTmpOverDevShm) {
ShmStrategy strategy;
ASMJIT_PROPAGATE(getShmStrategy(&strategy));
preferTmpOverDevShm = (strategy == ShmStrategy::kTmpDir);
}
AnonymousMemory anonMem;
ASMJIT_PROPAGATE(anonMem.open(preferTmpOverDevShm));
ASMJIT_PROPAGATE(anonMem.allocate(size));
void* ptr[2];
for (uint32_t i = 0; i < 2; i++) {
MemoryFlags accessFlags = memoryFlags & ~dualMappingFilter[i];
int protection = mmProtFromMemoryFlags(accessFlags) | mmMaxProtFromMemoryFlags(accessFlags);
ptr[i] = mmap(nullptr, size, protection, MAP_SHARED, anonMem.fd(), 0);
if (ptr[i] == MAP_FAILED) {
// Get the error now before `munmap()` has a chance to clobber it.
int e = errno;
if (i == 1)
munmap(ptr[0], size);
return DebugUtils::errored(asmjitErrorFromErrno(e));
}
}
dm->rx = ptr[0];
dm->rw = ptr[1];
return kErrorOk;
}
Error releaseDualMapping(DualMapping* dm, size_t size) noexcept {
Error err = release(dm->rx, size);
if (dm->rx != dm->rw)
err |= release(dm->rw, size);
if (err)
return DebugUtils::errored(kErrorInvalidArgument);
dm->rx = nullptr;
dm->rw = nullptr;
return kErrorOk;
}
#endif
// Virtual Memory - Flush Instruction Cache
// ========================================
void flushInstructionCache(void* p, size_t size) noexcept {
#if ASMJIT_ARCH_X86
// X86/X86_64 architecture doesn't require to do anything to flush instruction cache.
DebugUtils::unused(p, size);
#elif defined(__APPLE__)
sys_icache_invalidate(p, size);
#elif defined(_WIN32)
// Windows has a built-in support in `kernel32.dll`.
FlushInstructionCache(GetCurrentProcess(), p, size);
#elif defined(__GNUC__)
char* start = static_cast<char*>(p);
char* end = start + size;
__builtin___clear_cache(start, end);
#else
#pragma message("asmjit::VirtMem::flushInstructionCache() doesn't have implementation for the target OS and compiler")
DebugUtils::unused(p, size);
#endif
}
// Virtual Memory - Memory Info
// ============================
Info info() noexcept {
static std::atomic<uint32_t> vmInfoInitialized;
static Info vmInfo;
if (!vmInfoInitialized.load()) {
Info localMemInfo;
getVMInfo(localMemInfo);
vmInfo = localMemInfo;
vmInfoInitialized.store(1u);
}
return vmInfo;
}
// Virtual Memory - Hardened Runtime Info
// ======================================
HardenedRuntimeInfo hardenedRuntimeInfo() noexcept {
return HardenedRuntimeInfo { getHardenedRuntimeFlags() };
}
// Virtual Memory - Project JIT Memory
// ===================================
void protectJitMemory(ProtectJitAccess access) noexcept {
#if defined(ASMJIT_HAS_PTHREAD_JIT_WRITE_PROTECT_NP)
pthread_jit_write_protect_np(static_cast<uint32_t>(access));
#else
DebugUtils::unused(access);
#endif
}
ASMJIT_END_SUB_NAMESPACE
#endif