I am working on ELF-injector, which given some payload (currently it's an assembly file with .text section only) will inject it into ELF binary. I had related post here.
Now I would like to make it more usable and allow the payload call library functions linked by the victim (at least libc functions).
Note: I am changing first instructions of the entry point to execute my code first. Does it mean I cannot yet use dynamically linked functions?