https://github.com/maximilianfeldthusen/disasmlinuxelf
simpel code to disassembling an Linux ELF using libelf * library along with libdwarf
https://github.com/maximilianfeldthusen/disasmlinuxelf
Last synced: 6 months ago
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simpel code to disassembling an Linux ELF using libelf * library along with libdwarf
- Host: GitHub
- URL: https://github.com/maximilianfeldthusen/disasmlinuxelf
- Owner: maximilianfeldthusen
- License: bsd-3-clause
- Created: 2024-04-21T05:16:31.000Z (over 1 year ago)
- Default Branch: TFD
- Last Pushed: 2025-02-27T07:10:27.000Z (7 months ago)
- Last Synced: 2025-02-27T08:47:40.289Z (7 months ago)
- Language: C++
- Size: 16.6 KB
- Stars: 0
- Watchers: 1
- Forks: 0
- Open Issues: 0
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Metadata Files:
- Readme: README.md
- License: LICENSE
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README
## Documentation
### DisasmLinuxElf
This C++ program is designed to read and process an ELF (Executable and Linkable Format) file, which is commonly used for executable files, object code, shared libraries, and core dumps in Unix-like operating systems. The program effectively opens an ELF file, retrieves its sections, and checks for sections that contain executable code. Below is a breakdown of the key components and functionalities of the code:
### Key Components and Functionality
1. **Header Files**:
- `#include `: For input and output operations.
- `#include `: For ELF file format definitions and structures.
- `#include `: For ELF manipulation functions (requires linking against the `libelf` library).
- `#include `, `#include `, `#include `, `#include `: For file operations.
- `#include `: For string manipulation functions like `strerror()`.
- `#include `: For error number handling.
2. **Main Function**:
- `int main(int argc, char *argv[])`: Entry point of the program.
- The program checks if an ELF file path is provided as a command-line argument. If not, it prints the usage information and exits.
3. **Opening the ELF File**:
- The program attempts to open the ELF file specified in the command-line arguments using `open()`. If it fails, it prints an error message and exits.
4. **Initializing the ELF Library**:
- The program initializes the ELF library using `elf_version()`. If initialization fails, it prints an error message and exits.
5. **Reading the ELF Header**:
- The program uses `elf_begin()` to prepare for reading the ELF file, then retrieves the ELF header using `elf64_getehdr()`. If this fails, it cleans up and exits.
6. **Iterating Through Sections**:
- The program uses a loop with `elf_nextscn()` to iterate through all sections of the ELF file.
- For each section, it retrieves the section header with `elf64_getshdr()`. If this fails, it cleans up and exits.
7. **Checking for Executable Sections**:
- It checks if the section has the `SHF_EXECINSTR` flag, indicating that it contains executable code.
- If the section contains executable code, it retrieves the section data using `elf_getdata()`.
8. **Disassembling Code**:
- The program iterates over the bytes of the section data, printing the address and byte value in hexadecimal format.
- There is a placeholder comment (`// TODO: Implement instruction disassembly using libdwarf or other libraries`) indicating that the actual disassembly of instructions is not implemented in this code.
9. **Cleanup**:
- After processing all sections, the program cleans up by calling `elf_end()` to close the ELF descriptor and `close(fd)` to close the file descriptor for the ELF file.
10. **Completion Message**:
- Finally, the program prints a message indicating that disassembly is finished.
### Summary
In essence, this program serves as a foundation for analyzing ELF files, specifically focusing on executable sections. While it prints the raw byte values of instructions, it lacks the actual disassembly logic, which would require further implementation using disassembly libraries or technique.
### Notes
Disassembly: The actual disassembly functionality is still marked as TODO. You need a disassembly library or function to convert raw bytes into human-readable assembly instructions.
Error Messages: The code now includes more informative error messages using strerror(errno) for file-related errors.
Use of sh_size: The code iterates over the section size instead of using sh_entsize, which is more appropriate for executable code sections.
Compiling: When compiling, make sure you link against the necessary libraries:
g++ -o elf_disassembler elf_disassembler.cpp -lelf -ldwarf
Execution: Run the program with the path to an ELF file as an argument:
./elf_disassembler /path/to/your/file.elf
Make sure to adjust the disassembly part according to the library you decide to use for that purpose.
