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Add (hopefully) Wine/Proton compatible fix for NtProtectVirtualMemory
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The previous fix assumed that ntdll's NtProtectVirtualMemory
Had a Windows layout and was not reimplemented like Wine does
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@praydog
praydog committed Feb 4, 2024
1 parent d46e7d5 commit 8265afb
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Showing 2 changed files with 83 additions and 63 deletions.
142 changes: 79 additions & 63 deletions src/mods/IntegrityCheckBypass.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -524,7 +524,14 @@ void IntegrityCheckBypass::setup_pristine_syscall() {

spdlog::info("[IntegrityCheckBypass]: Copying pristine NtProtectVirtualMemory...");

auto nt_protect_virtual_memory = (NtProtectVirtualMemory_t)GetProcAddress(GetModuleHandleA("ntdll.dll"), "NtProtectVirtualMemory");
const auto ntdll_base = GetModuleHandleA("ntdll.dll");

if (ntdll_base == nullptr) {
spdlog::error("[IntegrityCheckBypass]: Could not find ntdll!");
return;
}

auto nt_protect_virtual_memory = (NtProtectVirtualMemory_t)GetProcAddress(ntdll_base, "NtProtectVirtualMemory");
if (nt_protect_virtual_memory == nullptr) {
spdlog::error("[IntegrityCheckBypass]: Could not find NtProtectVirtualMemory!");
return;
Expand All @@ -537,8 +544,21 @@ void IntegrityCheckBypass::setup_pristine_syscall() {
nt_protect_virtual_memory = (decltype(nt_protect_virtual_memory))utility::calculate_absolute((uintptr_t)nt_protect_virtual_memory + 1);
}

s_og_protect_virtual_memory = nt_protect_virtual_memory;

// Mark the original VirtualProtect READ_WRITE_EXECUTE so if anything tries to restore the old protection, it will revert to this
// incase trying to modify the protection after it is hooked causes a crash
DWORD old_nt_protect_virtual_memory_protect{};
VirtualProtect(nt_protect_virtual_memory, 256, PAGE_EXECUTE_READWRITE, &old_nt_protect_virtual_memory_protect);

s_pristine_protect_virtual_memory = (decltype(s_pristine_protect_virtual_memory))VirtualAlloc(nullptr, 256, MEM_COMMIT | MEM_RESERVE, PAGE_EXECUTE_READWRITE);
memcpy(s_pristine_protect_virtual_memory, nt_protect_virtual_memory, 256);

try {
memcpy(s_pristine_protect_virtual_memory, nt_protect_virtual_memory, 256);
} catch(...) {
spdlog::error("[IntegrityCheckBypass]: Could not copy new instructions to pristine NtProtectVirtualMemory!");
}

spdlog::info("[IntegrityCheckBypass]: Copied NtProtectVirtualMemory to 0x{:X}", (uintptr_t)s_pristine_protect_virtual_memory);
}

Expand All @@ -548,57 +568,6 @@ void IntegrityCheckBypass::fix_virtual_protect() try {

setup_pristine_syscall(); // Called earlier in DllMain

// Now disassemble our pristine function and just remove anything that looks like its a displacement or memory reference with nops
// im doing this because im too lazy to fix up the relocations
struct PatchJob {
uintptr_t addr{};
uint32_t size{};
};

std::vector<PatchJob> patch_jobs{};

utility::exhaustive_decode((uint8_t*)s_pristine_protect_virtual_memory, 100, [&](utility::ExhaustionContext& ctx) -> utility::ExhaustionResult {
if (*(uint8_t*)ctx.addr == 0x0f && *(uint8_t*)(ctx.addr + 1) == 0x05) {
spdlog::info("[IntegrityCheckBypass]: Found syscall at 0x{:X}", ctx.addr);
return utility::ExhaustionResult::CONTINUE;
}

if (std::string_view{ctx.instrux.Mnemonic}.starts_with("RET") || std::string_view{ctx.instrux.Mnemonic}.starts_with("INT")) {
return utility::ExhaustionResult::CONTINUE;
}

if (ctx.instrux.BranchInfo.IsBranch) {
spdlog::info("[IntegrityCheckBypass]: Found branch at 0x{:X} ({:x})", ctx.addr, ctx.addr - (uintptr_t)s_pristine_protect_virtual_memory);
spdlog::info("[IntegrityCheckBypass]: {}", ctx.instrux.Mnemonic);
patch_jobs.push_back(PatchJob{ctx.addr, ctx.instrux.Length});
return utility::ExhaustionResult::CONTINUE;
}

if (utility::resolve_displacement(ctx.addr).has_value()) {
spdlog::info("[IntegrityCheckBypass]: Found displacement at 0x{:X} ({:x})", ctx.addr, ctx.addr - (uintptr_t)s_pristine_protect_virtual_memory);
patch_jobs.push_back(PatchJob{ctx.addr, ctx.instrux.Length});
return utility::ExhaustionResult::CONTINUE;
}

// Go through any operands and check if any mem
for (auto i = 0; i < ctx.instrux.OperandsCount; ++i) {
const auto& op = ctx.instrux.Operands[i];

if (op.Type == ND_OP_MEM) {
spdlog::info("[IntegrityCheckBypass]: Found mem operand at 0x{:X} ({:x})", ctx.addr, ctx.addr - (uintptr_t)s_pristine_protect_virtual_memory);
patch_jobs.push_back(PatchJob{ctx.addr, ctx.instrux.Length});
return utility::ExhaustionResult::CONTINUE;
}
}

return utility::ExhaustionResult::CONTINUE;
});

for (auto& patch_job : patch_jobs) {
spdlog::info("[IntegrityCheckBypass]: Patching 0x{:X} with {} nops", patch_job.addr, patch_job.size);
memset((void*)patch_job.addr, 0x90, patch_job.size);
}

// Hook VirtualProtect
s_virtual_protect_hook = std::make_unique<FunctionHook>(VirtualProtect, (uintptr_t)virtual_protect_hook);
if (!s_virtual_protect_hook->create()) {
Expand All @@ -611,18 +580,11 @@ void IntegrityCheckBypass::fix_virtual_protect() try {
spdlog::error("[IntegrityCheckBypass]: Could not fix VirtualProtect!");
}

// This allows our calls to VirtualProtect to go through without being hindered by... something.
BOOL WINAPI IntegrityCheckBypass::virtual_protect_hook(LPVOID lpAddress, SIZE_T dwSize, DWORD flNewProtect, PDWORD lpflOldProtect) try {
static bool once = true;
if (once) {
spdlog::info("[IntegrityCheckBypass]: VirtualProtect called");
once = false;
}

BOOL WINAPI IntegrityCheckBypass::virtual_protect_impl(LPVOID lpAddress, SIZE_T dwSize, DWORD flNewProtect, PDWORD lpflOldProtect) {
static const auto this_process = GetCurrentProcess();

LPVOID address_to_protect = lpAddress;
NTSTATUS result = s_pristine_protect_virtual_memory(this_process, (PVOID*)&address_to_protect, &dwSize, flNewProtect, lpflOldProtect);
NTSTATUS result = s_og_protect_virtual_memory(this_process, (PVOID*)&address_to_protect, &dwSize, flNewProtect, lpflOldProtect);

constexpr NTSTATUS STATUS_INVALID_PAGE_PROTECTION = 0xC0000045;

Expand All @@ -633,7 +595,7 @@ BOOL WINAPI IntegrityCheckBypass::virtual_protect_hook(LPVOID lpAddress, SIZE_T

if (rtl_flush_secure_memory_cache != nullptr) {
if (NT_SUCCESS(rtl_flush_secure_memory_cache(address_to_protect, dwSize))) {
result = s_pristine_protect_virtual_memory(this_process, (PVOID*)&address_to_protect, &dwSize, flNewProtect, lpflOldProtect);
result = s_og_protect_virtual_memory(this_process, (PVOID*)&address_to_protect, &dwSize, flNewProtect, lpflOldProtect);

if ((result & 0x80000000) == 0) {
return TRUE;
Expand All @@ -647,6 +609,60 @@ BOOL WINAPI IntegrityCheckBypass::virtual_protect_hook(LPVOID lpAddress, SIZE_T
}

return NT_SUCCESS(result);
}

// This allows our calls to VirtualProtect to go through without being hindered by... something.
BOOL WINAPI IntegrityCheckBypass::virtual_protect_hook(LPVOID lpAddress, SIZE_T dwSize, DWORD flNewProtect, PDWORD lpflOldProtect) try {
static bool once = true;
if (once) {
spdlog::info("[IntegrityCheckBypass]: VirtualProtect called");
once = false;
}

try {
if (memcmp(s_og_protect_virtual_memory, s_pristine_protect_virtual_memory, 32) != 0) {
spdlog::warn("[IntegrityCheckBypass]: Original NtProtectVirtualMemory has been modified! Attempting to restore...");

bool needs_protection_fix = false;

try {
memcpy(s_og_protect_virtual_memory, s_pristine_protect_virtual_memory, 32);

if (memcmp(s_og_protect_virtual_memory, s_pristine_protect_virtual_memory, 32) == 0) {
spdlog::info("[IntegrityCheckBypass]: Successfully restored NtProtectVirtualMemory");
} else {
needs_protection_fix = true;
spdlog::error("[IntegrityCheckBypass]: Could not restore NtProtectVirtualMemory without changing protection!");
}
} catch(...) {
needs_protection_fix = true;
spdlog::error("[IntegrityCheckBypass]: Could not restore NtProtectVirtualMemory without changing protection! Attempting to restore protection anyway...");
}

if (needs_protection_fix) try {
spdlog::info("[IntegrityCheckBypass]: Attempting to restore NtProtectVirtualMemory protection");

DWORD old{};

// Now this is a huge assumption that the hook that was placed on NtProtectVirtualMemory
// does not prevent calling it on itself, which is a very dangerous assumption to make.
// Usually it fails if it's attempted to be called on the executable's memory, but not other modules.
// However I have tested it and it *does* work, so we will roll with that for now, until it doesn't.
if (virtual_protect_impl((void*)((uintptr_t)s_og_protect_virtual_memory - 1), 33, PAGE_EXECUTE_READWRITE, &old)) {
memcpy(s_og_protect_virtual_memory, s_pristine_protect_virtual_memory, 32);
virtual_protect_impl((void*)((uintptr_t)s_og_protect_virtual_memory - 1), 33, old, &old);

spdlog::info("[IntegrityCheckBypass]: Restored NtProtectVirtualMemory");
}
} catch(...) {
spdlog::error("[IntegrityCheckBypass]: Could not restore NtProtectVirtualMemory protection!");
}
}
} catch(...) {
spdlog::error("[IntegrityCheckBypass]: Failed to verify NtProtectVirtualMemory integrity!");
}

return virtual_protect_impl(lpAddress, dwSize, flNewProtect, lpflOldProtect);
} catch(...) {
spdlog::error("[IntegrityCheckBypass]: VirtualProtect hook failed! falling back to original");
return s_virtual_protect_hook->get_original<decltype(virtual_protect_hook)>()(lpAddress, dwSize, flNewProtect, lpflOldProtect);
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4 changes: 4 additions & 0 deletions src/mods/IntegrityCheckBypass.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -26,10 +26,14 @@ class IntegrityCheckBypass : public Mod {
static void fix_virtual_protect();

private:
static BOOL WINAPI virtual_protect_impl(LPVOID lpAddress, SIZE_T dwSize, DWORD flNewProtect, PDWORD lpflOldProtect);
static BOOL WINAPI virtual_protect_hook(LPVOID lpAddress, SIZE_T dwSize, DWORD flNewProtect, PDWORD lpflOldProtect);

using NtProtectVirtualMemory_t = NTSTATUS(NTAPI*)(HANDLE ProcessHandle, PVOID* BaseAddress, SIZE_T* NumberOfBytesToProtect, ULONG NewAccessProtection, PULONG OldAccessProtection);
static inline NtProtectVirtualMemory_t s_pristine_protect_virtual_memory{ nullptr };
static inline NtProtectVirtualMemory_t s_og_protect_virtual_memory{ nullptr };

static inline std::unique_ptr<FunctionHook> s_get_proc_address_hook{};
static inline std::unique_ptr<FunctionHook> s_virtual_protect_hook{};

#ifdef RE3
Expand Down

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