I am planning on putting tags in the symbol table, and then using them as pointers into the code to change the code at run-time.
I already have the symbol table setup, now I just need to modify the application's code when it loads. All I need to do is change values passed to a pushl instruction, which are tagged by my symbols I have added to the symbol table.
For example:
pushl $12345678 call foo
could be changed to
pushl $87654321 call foo
at run-time
I am using the symbol table, because it seems like a good place to store the locations of these instructions. Then, when the program loads, I will run through the symbols, and change the correct bytes as needed.
I am assuming I need to modify execve() to do this, or can this be done otherwise?
System: Redhat Linux 9 x86 arch
Regards, Brian
