staq 0.1.13

Stack Visualization Tool

Staq is a python package for simulating/visualizing stack operations. It also provides a sphinx extension for generating stack diagrams

Install

pip install staq

CLI

To run the cli,

staq

This will start the cli interface. Here is a quick example of some commands:

(staq)>>  push etc: ... --size 64
(staq)>>  call main(2, "hello" "world")
(staq)>>  char buffer[64]
(staq)>>  push i: 0x89 --note Same as 'int i = 0x89'
(staq)>>  call printf("vars %d %d", 17, 38)
(staq)>>  function myFunction(int a, int b)
(staq)>>  call myFunction(56,78)

Because this is really just a tool for visualization, types are not strictly defined or used. For instance the following command is valid:

It will add a word to the stack with label i and value “index of buffer”

Local vars

you can declare local variables using standard C syntax.

char buffer[64]
int i = 0x89

Loading a C file

You can load a file with C syntax to import functions. The functions will be loaded into the context including arguments, local variables, and calls to other functions.

load test.c

Write

The write command lets you write data to the stack at a given address.

write 0x56, 0x78, 0x90, 0x12 -a 0x1000

#you can also use references to variables with offsets
write 0x45 -a &buffer
write 0x45 -a &buffer+4

Push

push will push a single stack cell onto the stack. A cell contains one or more words. Each cell can have a label, note, and words

push arg1: 0x56                 #Shortcut for 'push 0x56 --label arg1'
push --label buffer --size 64   #creates a 64 word cell with no specified data
push buf: 1,2,3,4,5             #creates a 5 word cell with the values filled in
push <main+0x54> --note return  #creates a single word on the stack with no label, and a note

Pop

pop will remove words from the stack

pop             #remove a single word
pop 4           #remove 4 words
pop frame       #remove current frame

ret

ret will pop one word and set the instruction pointer to the value popped.

Note

the CallingConvention has a concept of registers, but they are not utilized/shown yet

Functions

The call command gets run through a CallingConvention subclass (currently only cdecl is available) and performs operations according to the convention:

• push arguments to stack

• create a new stack frame

• pushes return address

You can declare functions to give the app context about argument type/size and labels, but you can also call arbitrary functions. It will just assume all arguments are a single row on the stack.

function myFunction(int a, int b)
call myFunction(41,32)

call undeclareFunction(1,2,3,4)     # Will assume all args are 32 bit values and label arg1, arg2, arg3, etc

Note

A lot of common functions from libc are already loaded in.

run

The run command is similar to call, but it will continue calling the first known function call in each function until it runs out of calls or hits the –limit arg.

Sphinx

Important

not yet implemented

This package also contains an extension for sphinx. Add the extension in conf.py and then you can use the stack directive

.. stack::
    :showAddresses:

    push etc: ... --size 64
    call main(2, "hello" "world")
    char buffer[64]
    call printf("vars %d %d", 17, 38)
    function myFunction(int a, int b)
    call myFunction(56,78)