More progress with syscall hooking

src/driver/ept.cpp

@@ -7,16 +7,6 @@
 #include "memory.hpp"
 #include "vmx.hpp"
 
-#define MTRR_PAGE_SIZE 4096
-#define MTRR_PAGE_MASK (~(MTRR_PAGE_SIZE-1))
-
-#define ADDRMASK_EPT_PML1_OFFSET(_VAR_) ((_VAR_) & 0xFFFULL)
-
-#define ADDRMASK_EPT_PML1_INDEX(_VAR_) (((_VAR_) & 0x1FF000ULL) >> 12)
-#define ADDRMASK_EPT_PML2_INDEX(_VAR_) (((_VAR_) & 0x3FE00000ULL) >> 21)
-#define ADDRMASK_EPT_PML3_INDEX(_VAR_) (((_VAR_) & 0x7FC0000000ULL) >> 30)
-#define ADDRMASK_EPT_PML4_INDEX(_VAR_) (((_VAR_) & 0xFF8000000000ULL) >> 39)
-
 namespace vmx
 {
 	namespace
@@ -301,7 +291,7 @@ namespace vmx
 
 		// --------------------------
 
-		epdpte temp_epdpte;
+		epdpte temp_epdpte{};
 		temp_epdpte.flags = 0;
 		temp_epdpte.read_access = 1;
 		temp_epdpte.write_access = 1;

src/driver/ept.hpp

@@ -3,6 +3,18 @@
 #define DECLSPEC_PAGE_ALIGN DECLSPEC_ALIGN(PAGE_SIZE)
 #include "list.hpp"
 
+
+#define MTRR_PAGE_SIZE 4096
+#define MTRR_PAGE_MASK (~(MTRR_PAGE_SIZE-1))
+
+#define ADDRMASK_EPT_PML1_OFFSET(_VAR_) ((_VAR_) & 0xFFFULL)
+
+#define ADDRMASK_EPT_PML1_INDEX(_VAR_) (((_VAR_) & 0x1FF000ULL) >> 12)
+#define ADDRMASK_EPT_PML2_INDEX(_VAR_) (((_VAR_) & 0x3FE00000ULL) >> 21)
+#define ADDRMASK_EPT_PML3_INDEX(_VAR_) (((_VAR_) & 0x7FC0000000ULL) >> 30)
+#define ADDRMASK_EPT_PML4_INDEX(_VAR_) (((_VAR_) & 0xFF8000000000ULL) >> 39)
+
+
 namespace vmx
 {
 	using pml4 = ept_pml4;
@@ -11,6 +23,11 @@ namespace vmx
 	using pml2_ptr = epde;
 	using pml1 = epte;
 
+	using pml4_entry = pml4e_64;
+	using pml3_entry = pdpte_64;
+	using pml2_entry = pde_64;
+	using pml1_entry = pte_64;
+
 	struct ept_split
 	{
 		DECLSPEC_PAGE_ALIGN pml1 pml1[EPT_PTE_ENTRY_COUNT]{};

src/driver/hypervisor.cpp

@@ -15,10 +15,10 @@
 typedef struct _EPROCESS
 {
 	DISPATCHER_HEADER Header;
-	LIST_ENTRY        ProfileListHead;
-	ULONG_PTR         DirectoryTableBase;
-	UCHAR             Data[1];
-} EPROCESS, * PEPROCESS;
+	LIST_ENTRY ProfileListHead;
+	ULONG_PTR DirectoryTableBase;
+	UCHAR Data[1];
+} EPROCESS, *PEPROCESS;
 
 namespace
 {
@@ -485,10 +485,24 @@ void inject_interuption(const interruption_type type, const exception_vector vec
 	}
 }
 
-void inject_invalid_opcode(vmx::guest_context& guest_context)
+void inject_invalid_opcode()
 {
 	inject_interuption(hardware_exception, invalid_opcode, false, 0);
-	guest_context.increment_rip = false;
+}
+
+void inject_page_fault(const uint64_t page_fault_address)
+{
+	__writecr2(page_fault_address);
+
+	page_fault_exception error_code{};
+	error_code.flags = 0;
+
+	inject_interuption(hardware_exception, page_fault, true, error_code.flags);
+}
+
+void inject_page_fault(const void* page_fault_address)
+{
+	inject_page_fault(reinterpret_cast<uint64_t>(page_fault_address));
 }
 
 cr3 get_current_process_cr3()
@@ -517,41 +531,118 @@ enum class syscall_state
 {
 	is_sysret,
 	is_syscall,
+	page_fault,
 	none,
 };
 
+class scoped_cr3_switch
+{
+public:
+	scoped_cr3_switch()
+	{
+		original_cr3_.flags = __readcr3();
+	}
+
+	scoped_cr3_switch(const cr3 new_cr3)
+		: scoped_cr3_switch()
+	{
+		this->set_cr3(new_cr3);
+	}
+
+	scoped_cr3_switch(const scoped_cr3_switch&) = delete;
+	scoped_cr3_switch& operator=(const scoped_cr3_switch&) = delete;
+
+	scoped_cr3_switch(scoped_cr3_switch&&) = delete;
+	scoped_cr3_switch& operator=(scoped_cr3_switch&&) = delete;
+
+	~scoped_cr3_switch()
+	{
+		__writecr3(original_cr3_.flags);
+	}
+
+	void set_cr3(const cr3 new_cr3)
+	{
+		this->must_restore_ = true;
+		__writecr3(new_cr3.flags);
+	}
+
+private:
+	bool must_restore_{false};
+	cr3 original_cr3_{};
+};
+
+template <size_t Length>
+bool read_data_or_page_fault(uint8_t (&array)[Length], const uint8_t* base)
+{
+	for (size_t offset = 0; offset < Length;)
+	{
+		auto* current_base = base + offset;
+		auto* current_destination = array + offset;
+		auto read_length = Length - offset;
+
+		const auto* page_start = static_cast<uint8_t*>(PAGE_ALIGN(current_base));
+		const auto* next_page = page_start + PAGE_SIZE;
+
+		if (current_base + read_length > next_page)
+		{
+			read_length = next_page - current_base;
+		}
+
+		offset += read_length;
+
+		const auto physical_base = memory::get_physical_address(const_cast<uint8_t*>(current_base));
+
+		if (!physical_base)
+		{
+			inject_page_fault(current_base);
+			return false;
+		}
+
+		if (!memory::read_physical_memory(current_destination, physical_base, read_length))
+		{
+			// Not sure if we can recover from that :(
+			return false;
+		}
+	}
+
+	return true;
+}
+
 syscall_state get_syscall_state(const vmx::guest_context& guest_context)
 {
-	cr3 orignal_cr3{};
-	orignal_cr3.flags = __readcr3();
-
-	const auto _ = utils::finally([&]
-	{
-		__writecr3(orignal_cr3.flags);
-	});
+	scoped_cr3_switch cr3_switch{};
 
 	constexpr auto PCID_NONE = 0x000;
 	constexpr auto PCID_MASK = 0x003;
 
-	const auto guest_cr3 = read_vmx(VMCS_GUEST_CR3);
-	if ((guest_cr3 & PCID_MASK) != PCID_NONE)
+	cr3 guest_cr3{};
+	guest_cr3.flags = read_vmx(VMCS_GUEST_CR3);
+
+	if ((guest_cr3.flags & PCID_MASK) != PCID_NONE)
 	{
-		const auto process_cr3 = get_current_process_cr3();
-		__writecr3(process_cr3.flags);
+		cr3_switch.set_cr3(get_current_process_cr3());
 	}
 
-	// TODO: Check for potential page fault
 	const auto* rip = reinterpret_cast<uint8_t*>(guest_context.guest_rip);
 
-	constexpr uint8_t syscall_bytes[] = { 0x0F, 0x05 };
+	constexpr uint8_t syscall_bytes[] = {0x0F, 0x05};
 	constexpr uint8_t sysret_bytes[] = {0x48, 0x0F, 0x07};
 
-	if (is_mem_equal(rip, syscall_bytes))
+	constexpr auto max_byte_length = max(sizeof(sysret_bytes), sizeof(syscall_bytes));
+
+	uint8_t data[max_byte_length];
+
+	if (!read_data_or_page_fault(data, rip))
+	{
+		return syscall_state::page_fault;
+	}
+
+	if (is_mem_equal(data, syscall_bytes))
 	{
 		return syscall_state::is_syscall;
 	}
 
-	if (is_mem_equal(rip, sysret_bytes))
+	if (is_mem_equal(data, sysret_bytes))
 	{
 		return syscall_state::is_sysret;
 	}
@@ -573,12 +664,17 @@ void vmx_handle_exception(vmx::guest_context& guest_context)
 
 	if (interrupt.vector == invalid_opcode)
 	{
+		guest_context.increment_rip = false;
+
 		const auto state = get_syscall_state(guest_context);
 
+		if (state == syscall_state::page_fault)
+		{
+			return;
+		}
+
 		if (state == syscall_state::is_syscall)
 		{
-			guest_context.increment_rip = false;
-
 			rflags rflags{};
 			rflags.flags = read_vmx(VMCS_GUEST_RFLAGS);
 
@@ -617,8 +713,6 @@ void vmx_handle_exception(vmx::guest_context& guest_context)
 		}
 		else if (state == syscall_state::is_sysret)
 		{
-			guest_context.increment_rip = false;
-
 			__vmx_vmwrite(VMCS_GUEST_RIP, guest_context.vp_regs->Rcx);
 
 			rflags rflags{};
@@ -659,7 +753,7 @@ void vmx_handle_exception(vmx::guest_context& guest_context)
 		}
 		else
 		{
-			inject_invalid_opcode(guest_context);
+			inject_invalid_opcode();
 		}
 	}
 	else

src/driver/memory.cpp

@@ -68,6 +68,18 @@ namespace memory
 		return memory;
 	}
 
+	_IRQL_requires_max_(APC_LEVEL)
+
+	bool read_physical_memory(void* destination, uint64_t physical_address, const size_t size)
+	{
+		size_t bytes_read{};
+		MM_COPY_ADDRESS source{};
+		source.PhysicalAddress.QuadPart = static_cast<int64_t>(physical_address);
+
+		return MmCopyMemory(destination, source, size, MM_COPY_MEMORY_PHYSICAL, &bytes_read) == STATUS_SUCCESS &&
+			bytes_read == size;
+	}
+
 	uint64_t get_physical_address(void* address)
 	{
 		return static_cast<uint64_t>(MmGetPhysicalAddress(address).QuadPart);

src/driver/memory.hpp

@@ -10,6 +10,9 @@ namespace memory
 	_IRQL_requires_max_(DISPATCH_LEVEL)
 	void* allocate_aligned_memory(size_t size);
 
+	_IRQL_requires_max_(APC_LEVEL)
+	bool read_physical_memory(void* destination, uint64_t physical_address, size_t size);
+
 	uint64_t get_physical_address(void* address);
 	void* get_virtual_address(uint64_t address);
 

src/driver/nt_ext.hpp

@@ -56,6 +56,29 @@ MmAllocateContiguousNodeMemory(
 
 // ----------------------------------------
 
+typedef struct _MM_COPY_ADDRESS {
+	union {
+		PVOID VirtualAddress;
+		PHYSICAL_ADDRESS PhysicalAddress;
+	};
+} MM_COPY_ADDRESS, * PMMCOPY_ADDRESS;
+
+#define MM_COPY_MEMORY_PHYSICAL             0x1
+#define MM_COPY_MEMORY_VIRTUAL              0x2
+
+_IRQL_requires_max_(APC_LEVEL)
+NTKERNELAPI
+NTSTATUS
+MmCopyMemory(
+	_In_ PVOID TargetAddress,
+	_In_ MM_COPY_ADDRESS SourceAddress,
+	_In_ SIZE_T NumberOfBytes,
+	_In_ ULONG Flags,
+	_Out_ PSIZE_T NumberOfBytesTransferred
+);
+
+// ----------------------------------------
+
 NTSYSAPI
 VOID
 NTAPI