comments

hook.c

@@ -1,21 +1,22 @@
-/*
-\todo:
-What if there's a loop in the function which loops back to an overwritten instruction?
-start:
-	jmp hook_function
-	bla
-	jXX start+3
-
-*/
-
+// todo: on weird jump: stop the disassembling there or treat as normal instruction?
 #include <stdio.h>
 #include <stdlib.h>
 #include <assert.h>
 #include <stdbool.h>
-#include <Windows.h>
+#include <stddef.h>
+
+#ifdef WINDOWS
+#include <windows.h>
+#else
+#include <sys/mman.h>
+#include <string.h>
+
+#endif
+
 #include "udis86.h"
 #include "list.h"
 #include "hook.h"
+#include "misc.h"
 
 #define MINIMUM_REQUIRED_FUNCTION_LENGTH_SHORT_HOOK 5
 #define MINIMUM_REQUIRED_FUNCTION_LENGTH_LONG_HOOK 16
@@ -93,6 +94,9 @@ int hook(void* function, size_t functionLength, void* replacement, void** trampo
 		return (int)*trampoline;
 	printf("Needed for trampoline %p: %d (Found %d)\n", *trampoline, trampolineSizeNeeded, functionLength);
 
+#ifdef WINDOWS
+	FlushInstructionCache(GetCurrentProcess(), function, needed);
+#endif
 	return SUCCESS;
 }
 
@@ -111,7 +115,7 @@ static void* build_trampoline(void* function, size_t functionSize, size_t* tramp
 
 	*trampolineSize = 0;
 
-	if(!(trampoline = VirtualAlloc(NULL, PAGE_BOUNDARY, MEM_COMMIT | MEM_RESERVE, PAGE_EXECUTE_READWRITE)))
+	if(!(trampoline = alloc_rwx(PAGE_BOUNDARY)))
 		return (void*)CANT_ALLOC;
 	printf("trampoline @ %p\n", trampoline);
 
@@ -136,7 +140,7 @@ static void* build_trampoline(void* function, size_t functionSize, size_t* tramp
 		
 		// Check for XXX [rip + ?]
 		const struct ud_operand* op = NULL;
-		for(int i = 0; op = ud_insn_opr(&ud, i); i++)
+		for(int i = 0; ; i++, op = ud_insn_opr(&ud, i))
 		{
 			if((op->type & UD_OP_REG) == UD_OP_REG)
 			{
@@ -226,7 +230,7 @@ static int32_t get_rip_delta(ud_t* ud)
 	const struct ud_operand* op = NULL;
 	int32_t ret = 0;
 
-	for(int i = 0; op = ud_insn_opr(ud, i); i++)
+	for(int i = 0; ; i++, op = ud_insn_opr(ud, i))
 	{
 		// Only the RIP offset is interesting
 		if((op->type & UD_OP_REG) != UD_OP_REG || op->base != UD_R_RIP)
@@ -271,7 +275,7 @@ static size_t write_jcc_jump(const uint8_t* instruction, void* whereToWrite, voi
 static size_t get_jump_offset(ud_t* ud, size_t offsetOfInstr)
 {
 	const struct ud_operand* op = NULL;
-	for(int i = 0; op = ud_insn_opr(ud, i); i++)
+	for(int i = 0; ; i++, op = ud_insn_opr(ud, i))
 	{
 		if(op->type == UD_OP_JIMM)
 		{
@@ -360,8 +364,3 @@ static size_t write_x64_jump(unsigned char* where, void* toWhere)
 	return sizeof(jmpMemTemplate)+sizeof(toWhere);
 }
 
-//! fixme:
-static bool loops_into_overwritten_code(void* function)
-{
-	return false;
-}

hook.h

@@ -15,7 +15,8 @@ typedef enum HOOK_STATUS
 
 /**
 	\brief 
-	\param functionLength Length of the function you want to hook. If the length isn't known, pass 0 and the library will try to figure it out
+	\param functionLength Length of the function you want to hook.
+ 		If the length isn't known, pass 0 and the library will try to figure it out
 */
 int hook(void* function, size_t functionLength, void* replacement, void* trampoline);
 

main.c

@@ -1,5 +1,4 @@
 #include <stdio.h>
-#include <Windows.h>
 #include "misc.h"
 #include "hook.h"
 
@@ -47,8 +46,9 @@ int main(int argc, char** argv)
 	original(3, 1, 1, 1, 1);
 	//original(5, 1, 1, 1, 1);	
 
+#if WINDOWS
 	VirtualFree(original, 0, MEM_RELEASE);
-
+#endif
 	(void)getc(stdin);
 }
 

misc.c

@@ -1,15 +1,43 @@
 #include <stdio.h>
 #include <stdlib.h>
+#include <stdbool.h>
+#include <string.h>
+
+#ifdef WINDOWS
+#include <windows.h>
+#else
+#include <sys/mman.h>
+#endif
+
 #include "udis86.h"
 #include "misc.h"
 
+void* alloc_rwx(size_t size) {
+#ifdef WINDOWS
+	return VirtualAlloc(NULL, size, MEM_COMMIT | MEM_RESERVE, PAGE_EXECUTE_READWIRTE);
+#else
+	return mmap(NULL, size, PROT_READ | PROT_WRITE | PROT_EXEC, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+#endif
+}
+
+bool set_rwx(void* addr, size_t size) {
+#ifdef WINDOWS
+	DWORD tmp;
+	return VirtualProtect(addr, size, PAGE_EXECUTE_READWIRTE, &tmp) == TRUE;
+#else
+	return mprotect(addr, size, PROT_READ | PROT_WRITE | PROT_EXEC) == 0;
+#endif
+}
+
 void disassemble_func(void* function, size_t numberOfInstr)
 {
 	unsigned char* p = function;
 	ud_t ud;
 
 	ud_init(&ud);
-	ud_set_input_buffer(&ud, function, (size_t)function | (0x1000 - 1)); // Can't read further than page boundary - there be dragons
+	ud_set_input_buffer(&ud, function,
+						(size_t)function | (0x1000 - 1) // Can't read further than page boundary - there be dragons
+		);
 	ud_set_pc(&ud, (uint64_t)function);
 	ud_set_mode(&ud, 64);
 	ud_set_syntax(&ud, UD_SYN_INTEL);
@@ -24,7 +52,14 @@ void disassemble_func(void* function, size_t numberOfInstr)
 
 		printf("%p %s\n", ud_insn_off(&ud), ud_insn_asm(&ud));
 
-		// ugly, ugly hack todo: make it work
+		/* jmp qword [rip] is used by the hooking engine
+		 * x64 relative jumps don't exists so this way is used:
+		 * 	jmp qword [rip]
+		 * 	address where to tjump to
+		 * 	other code
+		 * Disassembling the address fucks up the dissassembling
+		 * todo: Follow all jump targets?
+		 */
 		if(strcmp(ud_insn_asm(&ud), "jmp qword [rip]") == 0)
 			p += 8;
 	}

misc.h

@@ -2,5 +2,7 @@
 #define MISC_H
 
 void disassemble_func(void* func, size_t numberOfInstr);
+bool set_rwx(void* addr, size_t size);
 
+void* alloc_rwx(size_t size);
 #endif MISC_H