christos 65c680cad7 Add PaX ASLR (Address Space Layout Randomization) [from elad and myself]
For regular (non PIE) executables randomization is enabled for:
    1. The data segment
    2. The stack

For PIE executables(*) randomization is enabled for:
    1. The program itself
    2. All shared libraries
    3. The data segment
    4. The stack

(*) To generate a PIE executable:
    - compile everything with -fPIC
    - link with -shared-libgcc -Wl,-pie

This feature is experimental, and might change. To use selectively add
    options PAX_ASLR=0
in your kernel.

Currently we are using 12 bits for the stack, program, and data segment and
16 or 24 bits for mmap, depending on __LP64__.
2007-12-26 22:11:47 +00:00
..