verity_memory/ops/write.rs
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use winapi::um::winnt::PAGE_EXECUTE_READWRITE;
use winapi::{shared::minwindef::LPVOID, um::memoryapi::VirtualProtect};
#[cfg(feature = "advanced-write")]
use crate::macros::match_number::{FloatType, IntegerType, IntegralType, NumberType};
#[cfg(feature = "advanced-write")]
use crate::types::Instruction;
use crate::{errors::WriteMemoryError, utils};
#[cfg(feature = "advanced-write")]
use crate::match_number;
#[cfg(feature = "advanced-write")]
use super::asm::{float_ret, get_instruction, integer_ret, integral_ret};
/// Writes a value of type `T` to the specified memory location.
///
/// # Safety
/// This function is unsafe because it directly manipulates raw pointers, which can cause undefined behavior
/// if the pointer is invalid or points to memory that is not writable.
///
/// # Parameters
/// - `dest_ptr`: A mutable pointer to the destination memory where the value will be written.
/// - `value`: The value to write at the destination memory.
///
/// # Returns
/// - `Ok(())` if the value was successfully written to memory.
/// - `Err(WriteMemoryError)` if an error occurred, such as a null pointer or invalid alignment.
///
/// # Errors
/// - `WriteMemoryError::NullPointer` if `dest_ptr` is null.
/// - `WriteMemoryError::InvalidAlignment` if `dest_ptr` is not correctly aligned.
/// - `WriteMemoryError::FailedToChangeProtection` if memory protection could not be modified.
/// - `WriteMemoryError::FailedToRestoreProtection` if memory protection could not be restored.
///
/// # Example
/// ```rust
/// use verity_memory::ops::write;
/// unsafe {
/// let mut value: i32 = 42;
/// let result = write::write_memory(&mut value as *mut i32, 100);
/// assert!(result.is_ok());
/// assert_eq!(value, 100);
/// }
/// ```
pub unsafe fn write_memory<T: Copy>(dest_ptr: *mut T, value: T) -> Result<(), WriteMemoryError> {
if dest_ptr.is_null() {
return Err(WriteMemoryError::NullPointer);
}
if !utils::check_alignment(dest_ptr) {
return Err(WriteMemoryError::InvalidAlignment);
}
let mut old_protect = 0;
let size = std::mem::size_of::<T>();
let res = VirtualProtect(
dest_ptr as LPVOID,
size,
PAGE_EXECUTE_READWRITE,
&mut old_protect,
);
if res == 0 {
return Err(WriteMemoryError::FailedToChangeProtection);
}
*dest_ptr = value;
let res_restore = VirtualProtect(dest_ptr as LPVOID, size, old_protect, &mut old_protect);
if res_restore == 0 {
return Err(WriteMemoryError::FailedToRestoreProtection);
}
Ok(())
}
/// Replaces a specified number of instructions at a memory location with NOPs (0x90).
///
/// # Safety
/// This function is unsafe because it directly modifies memory, which can corrupt the process
/// if the memory is not writable or if the replaced instructions are critical.
///
/// # Parameters
/// - `dest_ptr`: A mutable pointer to the memory location where instructions will be replaced.
/// - `num_instructions`: The number of instructions to replace with NOPs.
///
/// # Returns
/// - `Some(Vec<Instruction>)` containing the original instructions if successful.
/// - `None` if it failed to read instructions or write memory.
///
/// # Example
/// ```rust
/// use verity_memory::ops::write;
/// unsafe {
/// let buffer = vec![0x55, 0x48, 0x89, 0xE5]; // Some sample machine code (push rbp; mov rbp, rsp)
/// let original_instructions = write::nop_instructions(buffer.as_ptr() as *mut u8, 2);
/// assert!(original_instructions.is_some());
/// }
/// ```
#[cfg(feature = "advanced-write")]
pub unsafe fn nop_instructions(dest_ptr: *mut u8, num_instructions: usize) -> Option<Vec<Instruction>> {
let mut instructions = Vec::new();
let mut current_ptr = dest_ptr;
if num_instructions <= 0 {
panic!("You must nop at least one instruction...");
}
for _ in 0..num_instructions {
if let Some(instr) = get_instruction(current_ptr, 16) {
instructions.push(instr.clone());
current_ptr = current_ptr.add(instr.size);
} else {
eprintln!("Failed to get instruction at memory address: {:?}", current_ptr);
return None;
}
}
let total_size: usize = instructions.iter().map(|instr| instr.size).sum();
let nops = vec![0x90; total_size];
let mut written_size = 0;
for i in 0..num_instructions {
let instruction = &instructions[i];
for j in 0..instruction.size {
let res = write_memory(dest_ptr.add(written_size + j), nops[written_size + j]);
if let Err(e) = res {
eprintln!("Failed to write memory at offset {}: {:?}", written_size + j, e);
return None;
}
}
written_size += instruction.size;
}
Some(instructions)
}
/// Replaces the return value of a function with a specified value or inserts a `RET` instruction.
///
/// # Safety
/// This function is unsafe because it directly modifies memory, which can cause undefined behavior
/// if the memory is not writable or if the return value type is not correctly handled.
///
/// # Parameters
/// - `dest_ptr`: A mutable pointer to the function's first instruction.
/// - `return_value`: An optional value to return. If `None`, a `RET` instruction is written instead.
///
/// # Returns
/// - `Some(Instruction)` containing the original instruction if successful.
/// - `None` if an error occurred during instruction writing.
///
/// # Example
/// ```rust
/// use verity_memory::ops::write;
/// unsafe {
/// let buffer = vec![0x55, 0x48, 0x89, 0xE5]; // Example machine code
/// let result = write::replace_return_value::<i32>(buffer.as_ptr() as *mut u8, Some(123));
/// assert!(result.is_some());
/// }
/// ```
#[cfg(feature = "advanced-write")]
pub unsafe fn replace_return_value<T: Copy + 'static>(
dest_ptr: *mut u8,
return_value: Option<T>,
) -> Option<Instruction> {
let original_instruction = get_instruction(dest_ptr, 16)?;
let value = match return_value {
Some(val) => val,
None => {
if let Err(e) = write_memory(dest_ptr, 0xC3) {
eprintln!("Failed to write RET instruction: {:?}", e);
return None;
}
return Some(original_instruction);
}
};
let result = match_number!(value);
if result.is_none() {
return None;
}
let number_type = result.unwrap();
let instruction_bytes = match number_type {
NumberType::Float(float_type) => float_ret(float_type),
NumberType::Integer(integer_type) => integer_ret(integer_type),
NumberType::Integral(integral_type) => integral_ret(integral_type),
NumberType::Unknown => {
return None;
}
};
let mut current_ptr = dest_ptr;
for instruction_byte in instruction_bytes {
if write_memory(current_ptr, instruction_byte).is_err() {
return None;
}
current_ptr = current_ptr.add(1);
}
Some(original_instruction)
}
#[cfg(test)]
mod tests {
use super::*;
use std::ptr;
fn mock_dest_ptr<T: Copy>(value: T) -> *mut T {
let mut boxed_value = Box::new(value);
let ptr = &mut *boxed_value as *mut T;
std::mem::forget(boxed_value);
ptr
}
#[test]
fn test_write_memory_success() {
let value: u32 = 42;
let dest_ptr = mock_dest_ptr(value);
let result = unsafe { write_memory(dest_ptr, 100_u32) };
assert!(result.is_ok());
assert_eq!(unsafe { *dest_ptr }, 100_u32);
}
#[test]
fn test_write_memory_null_pointer() {
let dest_ptr: *mut u32 = ptr::null_mut();
let result = unsafe { write_memory(dest_ptr, 100_u32) };
assert!(matches!(result, Err(WriteMemoryError::NullPointer)));
}
#[test]
#[cfg(feature = "advanced-write")]
fn test_nop_instructions_success() {
let data: Vec<u8> = vec![0x55, 0x48, 0x8B, 0xEC, 0x90];
let dest_ptr = data.as_ptr() as *mut u8;
unsafe {
if let Some(instructions) = nop_instructions(dest_ptr, 2) {
assert_eq!(instructions.len(), 2);
} else {
panic!("Failed to retrieve instructions");
}
}
}
#[test]
#[cfg(feature = "advanced-write")]
fn test_nop_instructions_failure() {
let dest_ptr: *mut u8 = ptr::null_mut();
unsafe {
let instructions = nop_instructions(dest_ptr, 1);
assert!(instructions.is_none());
}
}
#[test]
#[cfg(feature = "advanced-write")]
fn test_replace_return_value_integer() {
let data: Vec<u8> = vec![0x55, 0x48, 0x8B, 0xEC];
let dest_ptr = data.as_ptr() as *mut u8;
unsafe {
let result = replace_return_value(dest_ptr, Some(123_u32));
assert!(result.is_some());
}
}
#[test]
#[cfg(feature = "advanced-write")]
fn test_replace_return_value_float() {
let data: Vec<u8> = vec![0x55, 0x48, 0x8B, 0xEC];
let dest_ptr = data.as_ptr() as *mut u8;
unsafe {
let result = replace_return_value(dest_ptr, Some(123.45_f32));
assert!(result.is_some());
}
}
#[test]
#[cfg(feature = "advanced-write")]
fn test_replace_return_value_none() {
let data: Vec<u8> = vec![0x55, 0x48, 0x8B, 0xEC];
let dest_ptr = data.as_ptr() as *mut u8;
unsafe {
let result = replace_return_value::<i32>(dest_ptr, None);
assert!(result.is_some());
}
}
}