Secure Memory Allocator

This project implements a secure memory allocator in C, developed as part of a school project. It provides functionalities similar to malloc, free, realloc, and calloc with added security measures.

Overview

The secure memory allocator aims to demonstrate fundamental concepts of memory management and security in C programming. It implements secure memory allocation techniques to prevent common vulnerabilities such as buffer overflows and memory leaks.

Features

• Secure Memory Allocation: Implements secure memory allocation techniques to prevent buffer overflows and other memory-related vulnerabilities.

• Block Merging: Optimizes memory usage by merging consecutive free memory blocks in the memory pool.

• Memory Block Reallocation: Supports reallocation of memory blocks using the realloc function, allowing resizing of memory blocks while preserving their contents.

• Detection of Memory Leaks: Tracks allocated memory blocks and ensures they are properly freed to prevent memory leaks.

• Custom Logging: Includes a custom logging mechanism for debugging purposes, allowing developers to print informative messages during runtime.

• Dynamic Memory Management: Provides custom implementations of memory allocation functions (malloc, free, calloc, realloc) for dynamic memory management.

Usage

To use the secure memory allocator in your project, follow these steps:

1. Include the header file my_secmalloc.private.h in your source files.
2. Link the compiled object file my_secmalloc.o with your executable.

#include "my_secmalloc.private.h"

int main() {
    // Allocate memory
    void* ptr = my_malloc(100);

    // Use the allocated memory

    // Free the allocated memory
    my_free(ptr);

    return 0;
}

Building

To build the project, simply run the make command in your terminal:

make

This will compile the source files and generate the executable.

Building Dynamic Library

To compile a dynamic library named libmy_secmalloc.so, use the following command:

make clean dynamic

This command will create the dynamic library in the lib/ directory. The library exports the following symbols:

$ nm lib/libmy_secmalloc.so | grep " T " | grep -v my_ | cut -f3 -d' ' | sort
calloc
free
malloc
realloc

Using LD_PRELOAD

You can use the LD_PRELOAD environment variable to force the use of your memory allocation functions for any program. For example:

LD_PRELOAD=./lib/libmy_secmalloc.so ./your_program

This will preload your secure memory allocator library (libmy_secmalloc.so) before executing your_program, ensuring that your memory allocation functions are used instead of the standard ones.

LOG

You can use the 'MSM_OUTPUT' environment variable to set the file descriptor and 'LOG_LVL' environment variable to set the verbosity.

LOG_LVL=DEBUG MSM_OUTPUT=stdout LD_PRELOAD=./lib/libmy_secmalloc.so ./your_program

Testing

To run the tests, execute the following command:

make test

This will compile the test suite and run the tests to ensure the proper functionality of the secure memory allocator.