[fuzzing] Python binding of ptrace for Linux and FreeBSD

[Victor Stinner]

Hi,

I wrote a Python binding of ptrace library for Linux and FreeBSD working on 
i386 and x86_64 (only i386 for FreeBSD). It supports quite all ptrace 
features and has nice Python objects. There are also two scripts to show 
binding features:

 * strace.py: clone of strace command
 * gdb.py: debugger similar to gdb (but in alpha stage)

The debugger supports multiple processes (attach new children using ptrace 
events), single step execution and hardware breakpoint. It uses distorm 
disassembler (optional).

The source code is distributed under GNU GPLv2 license.

Website: http://fusil.hachoir.org/trac/wiki/Ptrace

---

The PtraceProcess class has many methods:

 * disassemble() / disassembleOne(): disassemble some instructions
 * readStruct() / readArray() / readCString(): read data as Python objects
 * readBytes() / writeBytes(): use /proc/pid/mem (Linux only) or ptrace
   peek/poke methods, take care of memory align and split in CPU words
 * cont() / waitTrap()
 * getregs() / setreg() / setregs()
 * getInstrPointer()  / setInstrPointer()
 * getStackPointer()
 * findStack(): find stack start/end (use /proc/pid/maps)
 * terminate(): kill the process
 * etc.

---

PtraceProcess guess reason why it receives a signal, examples:

(a)  Signal: SIGFPE
     Division by zero! edi=0x00000000
     ASM: IDIV EDI

(b)  Signal: SIGSEGV
     FAULT ADDRESS: 0x08328000
     INVALID READ, registers: edi=0x00006110, ecx=0x08321ef0
     ASM: TEST [EDI+ECX], DL

---

Example of strace.py output:

   $ ./strace.py /bin/ls
   execve(/bin/ls, ['/bin/ls'], [/* 40 vars */]) = 756
   brk(0)                                   = 0x0805c000
   access('/etc/ld.so.nohwcap', 0)          = -2 (No such file or directory)
   mmap2(NULL, 8192, 3, 34, -1, 0)          = 0xb7f56000
   access('/etc/ld.so.preload', 4)          = -2 (No such file or directory)
   (...)
   close(1)                                 = 0
   munmap(0xb7c5c000, 4096)                 = 0
   exit_group(0)


Victor Stinner aka haypo