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peda.py
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# PEDA - Python Exploit Development Assistance for GDB
#
# Copyright (C) 2012 Long Le Dinh <longld at vnsecurity.net>
#
# License: see LICENSE file for details
#
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function
import re
import csv
import os
import sys
import shlex
import string
import time
import traceback
import codecs
import gdb
# point to absolute path of peda.py
PEDAFILE = os.path.abspath(os.path.expanduser(__file__))
if os.path.islink(PEDAFILE):
PEDAFILE = os.readlink(PEDAFILE)
sys.path.insert(0, os.path.dirname(PEDAFILE) + "/lib/")
# Use six library to provide Python 2/3 compatibility
import six
from six.moves import range, input
try:
import six.moves.cPickle as pickle
except ImportError:
import pickle
from shellcode import SHELLCODES, Shellcode
import utils
from utils import normalize_argv, memoized, format_reference_chain, format_disasm_code
from utils import to_int, to_hex, to_hexstr, hex2str, to_address, int2hexstr, list2hexstr, str2intlist
from utils import u32, u64, p32, p64
from utils import msg, warning_msg, error_msg, separator, pager
from utils import green, red, yellow, blue, purple, cyan
import config
from nasm import Nasm
if sys.version_info.major == 3:
pyversion = 3
else:
pyversion = 2
REGISTERS = {
8: ["al", "ah", "bl", "bh", "cl", "ch", "dl", "dh"],
16: ["ax", "bx", "cx", "dx"],
"elf32-i386": ["eax", "ebx", "ecx", "edx", "esi", "edi", "ebp", "esp", "eip"],
"elf64-x86-64": [
"rax", "rbx", "rcx", "rdx", "rsi", "rdi", "rbp", "rsp", "rip", "r8", "r9", "r10", "r11", "r12", "r13", "r14",
"r15"
],
"elf32-littlearm":
["r0", "r1", "r2", "r3", "r4", "r5", "r6", "r7", "r8", "r9", "r10", "r11", "r12", "sp", "lr", "pc"],
"elf32-tradlittlemips": [
"a0", "a1", "a2", "a3", "t0", "t1", "t2", "t3", "t4", "t5", "t6", "t7", "t8", "t9", "s0", "s1", "s2", "s3",
"s4", "s6", "s6", "s7", "gp", "sp", "s8", "ra", "pc"
],
"elf32-powerpc":
list(map(lambda x: "r%i" % x, range(32))) + ["pc", "lr"],
"elf64-littleaarch64":
list(map(lambda x: "x%i" % x, range(31))) + ["sp", "pc"] + list(map(lambda x: "w%i" % x, range(31)))
}
# pwndbg/commands/__init__.py
_mask = 0xffffffffFFFFFFFF
_mask_val_type = gdb.Value(_mask).type
###########################################################################
class PEDA(object):
"""
Class for actual functions of PEDA commands
"""
def __init__(self):
self.SAVED_COMMANDS = {} # saved GDB user's commands
self.enabled = True
####################################
# GDB Interaction / Misc Utils #
####################################
def execute(self, gdb_command, to_string=False):
"""
Wrapper for gdb.execute, catch the exception so it will not stop python script
Args:
- gdb_command (String)
Returns:
- True if execution succeed (Bool)
- Results of command (String)
"""
try:
out = gdb.execute(gdb_command, to_string=to_string)
if to_string:
return out
else:
return True
except Exception as e:
if config.Option.get("debug") == "on":
msg('Exception (%s): %s' % (gdb_command, e), "red")
traceback.print_stack()
return False
def parse_and_eval(self, exp):
"""
Wrapper for gdb.parse_and_eval
Only used in parsing asm and cmd argv
Args:
- exp: expression to evaluate (String)
Returns:
- value of expression (Int)
"""
(arch, _) = self.getarch()
if "aarch64" in arch:
regs = REGISTERS["elf64-littleaarch64"]
elif "arm" in arch:
regs = REGISTERS["elf32-littlearm"]
else:
regs = REGISTERS["elf64-x86-64"] + REGISTERS["elf32-i386"] + REGISTERS[16] + REGISTERS[8]
for r in regs:
if "$" + r not in exp and "e" + r not in exp and "r" + r not in exp:
exp = exp.replace(r, "$%s" % r)
try:
return int(gdb.parse_and_eval(exp).cast(_mask_val_type)) # no harm to cast to the longest type
except gdb.error:
return None
def string_to_argv(self, str_arg):
"""
Convert a string to argv list, pre-processing register and variable values
Args:
- str_arg: input string (String)
Returns:
- argv list (List)
"""
try:
str_arg = str_arg.encode('ascii', 'ignore')
except:
pass
args = list(map(lambda x: utils.decode_string_escape(x), shlex.split(str_arg.decode())))
# need more processing here
for idx, arg in enumerate(args):
arg = arg.strip(",")
if arg.startswith("+"): # relative value to prev arg
adder = self.parse_and_eval(arg[1:])
if adder is not None:
args[idx] = to_hex(to_int(args[idx - 1]) + adder)
elif '$' in arg or utils.is_math_exp(arg):
v = self.parse_and_eval(arg)
if v is not None:
args[idx] = str(v)
if config.Option.get("verbose") == "on":
msg(args)
return args
################################
# GDB User-Defined Helpers #
################################
def save_user_command(self, cmd):
"""
Save user-defined command and deactivate it
Args:
- cmd: user-defined command (String)
Returns:
- True if success to save (Bool)
"""
commands = self.execute("show user %s" % cmd, to_string=True)
if not commands:
return False
commands = "\n".join(commands.splitlines()[1:])
commands = "define %s\n" % cmd + commands + "end\n"
self.SAVED_COMMANDS[cmd] = commands
tmp = utils.tmpfile()
tmp.write("define %s\nend\n" % cmd)
tmp.flush()
result = self.execute("source %s" % tmp.name)
tmp.close()
return result
def define_user_command(self, cmd, code):
"""
Define a user-defined command, overwrite the old content
Args:
- cmd: user-defined command (String)
- code: gdb script code to append (String)
Returns:
- True if success to define (Bool)
"""
commands = "define %s\n" % cmd + code + "\nend\n"
tmp = utils.tmpfile(is_binary_file=False)
tmp.write(commands)
tmp.flush()
result = self.execute("source %s" % tmp.name)
tmp.close()
return result
def append_user_command(self, cmd, code):
"""
Append code to a user-defined command, define new command if not exist
Args:
- cmd: user-defined command (String)
- code: gdb script code to append (String)
Returns:
- True if success to append (Bool)
"""
commands = self.execute("show user %s" % cmd, to_string=True)
if not commands:
return self.define_user_command(cmd, code)
# else
commands = "\n".join(commands.splitlines()[1:])
if code in commands:
return True
commands = "define %s\n" % cmd + commands + code + "\nend\n"
tmp = utils.tmpfile()
tmp.write(commands)
tmp.flush()
result = self.execute("source %s" % tmp.name)
tmp.close()
return result
def restore_user_command(self, cmd):
"""
Restore saved user-defined command
Args:
- cmd: user-defined command (String)
Returns:
- True if success to restore (Bool)
"""
if cmd == "all":
commands = "\n".join(self.SAVED_COMMANDS.values())
self.SAVED_COMMANDS = {}
else:
if cmd not in self.SAVED_COMMANDS:
return False
else:
commands = self.SAVED_COMMANDS[cmd]
self.SAVED_COMMANDS.pop(cmd)
tmp = utils.tmpfile()
tmp.write(commands)
tmp.flush()
result = self.execute("source %s" % tmp.name)
tmp.close()
return result
def run_gdbscript_code(self, code):
"""
Run basic gdbscript code as it is typed in interactively
Args:
- code: gdbscript code, lines are splitted by "\n" or ";" (String)
Returns:
- True if success to run (Bool)
"""
tmp = utils.tmpfile()
tmp.write(code.replace(";", "\n"))
tmp.flush()
result = self.execute("source %s" % tmp.name)
tmp.close()
return result
#########################
# Debugging Helpers #
#########################
@memoized
def is_target_remote(self):
"""
Check if current target is remote
Returns:
- True if target is remote (Bool)
"""
out = self.execute("info program", to_string=True)
if out and "serial line" in out: # remote target
return True
return False
@memoized
def getfile(self):
"""
Get exec file of debugged program
Returns:
- full path to executable file (String)
"""
result = None
out = self.execute('info files', to_string=True)
if out and '"' in out:
m = re.search(".*exec file:\s*`(.*)'", out)
if m:
result = m.group(1)
else: # stripped file, get symbol file
m = re.search("Symbols from \"([^\"]*)", out)
if m:
result = m.group(1)
return result
def get_status(self):
"""
Get execution status of debugged program
Returns:
- current status of program (String)
STOPPED - not being run
BREAKPOINT - breakpoint hit
SIGXXX - stopped by signal XXX
UNKNOWN - unknown, not implemented
"""
status = "UNKNOWN"
out = self.execute("info program", to_string=True)
for line in out.splitlines():
if line.startswith("It stopped"):
if "signal" in line: # stopped by signal
status = line.split("signal")[1].split(",")[0].strip()
break
if "breakpoint" in line: # breakpoint hit
status = "BREAKPOINT"
break
if "not being run" in line:
status = "STOPPED"
break
return status
@memoized
def getpid(self):
"""
Get PID of the debugged process
Returns:
- pid (Int)
"""
status = self.get_status()
if not status or status == "STOPPED":
return None
pid = gdb.selected_inferior().pid
return int(pid) if pid else None
def getos(self):
"""
Get running OS info
Returns:
- os version (String)
"""
# TODO: get remote os by calling uname()
return os.uname()[0]
@memoized
def getarch(self):
"""
Get architecture of debugged program
Returns:
- tuple of architecture info (arch (String), bits (Int))
"""
gdb_arch = self.execute('show architecture', to_string=True)
if 'i386:x86-64' in gdb_arch:
return ('elf64-x86-64', 64)
elif 'i386' in gdb_arch:
return ('elf32-i386', 32)
elif 'arm' in gdb_arch:
return ('elf32-littlearm', 32)
elif 'aarch64' in gdb_arch:
return ('elf64-littleaarch64', 64)
arch = "unknown"
bits = 32
out = self.execute('maintenance info sections ?', to_string=True).splitlines()
for line in out:
if "file type" in line:
arch = line.split()[-1][:-1]
break
if "64" in arch:
bits = 64
return (arch, bits)
@memoized
def intsize(self):
"""
Get dword size of debugged program
Returns:
- size (Int)
+ intsize = 4/8 for 32/64-bits arch
"""
(_, bits) = self.getarch()
return bits // 8
def unpack(self, s, intsize):
"""
Unpack a string to unsigned interger according to intsize
Returns:
- Unpack result (Int)
"""
if intsize == 8:
return u64(s)
elif intsize == 4:
return u32(s)
def pack(self, n, intsize):
"""
Pack a unsigned interger to string according to intsize
Returns:
- Pack result (String)
"""
if intsize == 8:
return p64(n)
elif intsize == 4:
return p32(n)
def getregs(self, reglist=None):
"""
Get value of some or all registers
Returns:
- dictionary of {regname(String) : value(Int)}
"""
if reglist:
reglist = reglist.replace(",", " ")
else:
reglist = ""
regs = self.execute("info registers %s" % reglist, to_string=True)
if not regs:
return None
result = {}
(arch, bits) = self.getarch()
if regs:
if "mips" in arch:
tmp = regs.splitlines()
klist = tmp[0].split() + tmp[2].split() + tmp[4].split() + tmp[6].split() + tmp[8].split(
) + tmp[10].split()
vlist = tmp[1].split()[1:] + tmp[3].split()[1:] + tmp[5].split()[1:] + tmp[7].split(
)[1:] + tmp[9].split() + tmp[11].split()
vlist = [to_int("0x" + v) for v in vlist]
result = dict(zip(klist, vlist))
else:
for r in regs.splitlines():
r = r.split()
if len(r) > 1 and to_int(r[1]) is not None:
result[r[0]] = to_int(r[1])
return result
def getreg(self, register):
"""
Get value of a specific register
Args:
- register: register name (String)
Returns:
- register value (Int)
"""
r = register.lower()
regs = self.execute("info registers %s" % r, to_string=True)
if regs:
regs = regs.splitlines()
if len(regs) > 1:
return None
else:
result = to_int(regs[0].split()[1])
return result
return None
def get_breakpoint(self, num):
"""
Get info of a specific breakpoint
TODO: support catchpoint, watchpoint
Args:
- num: breakpoint number
Returns:
- tuple (Num(Int), Type(String), Disp(Bool), Enb(Bool), Address(Int), What(String), commands(String))
"""
out = self.execute("info breakpoints %d" % num, to_string=True)
if not out or "No breakpoint" in out:
return None
lines = out.splitlines()[1:]
# breakpoint regex
m = re.match("^(\d*)\s*(.*breakpoint)\s*(keep|del)\s*(y|n)\s*(0x\S+)\s*(.*)", lines[0])
if not m:
# catchpoint/watchpoint regex
m = re.match("^(\d*)\s*(.*point)\s*(keep|del)\s*(y|n)\s*(.*)", lines[0])
if not m:
return None
else:
(num, type, disp, enb, what) = m.groups()
addr = ''
else:
(num, type, disp, enb, addr, what) = m.groups()
disp = True if disp == "keep" else False
enb = True if enb == "y" else False
addr = to_int(addr)
m = re.match("in.*at(.*:\d*)", what)
if m:
what = m.group(1)
else:
if addr: # breakpoint
what = ""
commands = ""
if len(lines) > 1:
for line in lines[1:]:
if "already hit" in line: continue
commands += line + "\n"
return (num, type, disp, enb, addr, what, commands.rstrip())
def get_breakpoints(self):
"""
Get list of current breakpoints
Returns:
- list of tuple (Num(Int), Type(String), Disp(Bool), Nnb(Bool), Address(Int), commands(String))
"""
result = []
out = self.execute("info breakpoints", to_string=True)
if not out:
return []
bplist = []
for line in out.splitlines():
m = re.match("^(\d*).*", line)
if m and to_int(m.group(1)):
bplist += [to_int(m.group(1))]
for num in bplist:
r = self.get_breakpoint(num)
if r:
result += [r]
return result
def save_breakpoints(self, filename):
"""
Save current breakpoints to file as a script
Args:
- filename: target file (String)
Returns:
- True if success to save (Bool)
"""
# use built-in command for gdb 7.2+
result = self.execute("save breakpoints %s" % filename, to_string=True)
if result == '':
return True
bplist = self.get_breakpoints()
if not bplist:
return False
try:
fd = open(filename, "w")
for (num, type, disp, enb, addr, what, commands) in bplist:
m = re.match("(.*)point", type)
if m:
cmd = m.group(1).split()[-1]
else:
cmd = "break"
if "hw" in type and cmd == "break":
cmd = "h" + cmd
if "read" in type:
cmd = "r" + cmd
if "acc" in type:
cmd = "a" + cmd
if not disp:
cmd = "t" + cmd
if what:
location = what
else:
location = "*%#x" % addr
text = "%s %s" % (cmd, location)
if commands:
if "stop only" not in commands:
text += "\ncommands\n%s\nend" % commands
else:
text += commands.split("stop only", 1)[1]
fd.write(text + "\n")
fd.close()
return True
except:
return False
def get_config_filename(self, name):
filename = self.getfile()
if not filename:
filename = self.getpid()
if not filename:
filename = 'unknown'
filename = os.path.basename("%s" % filename)
tmpl_name = config.Option.get(name)
if tmpl_name:
return tmpl_name.replace("#FILENAME#", filename)
else:
return "peda-%s-%s" % (name, filename)
def save_session(self, filename=None):
"""
Save current working gdb session to file as a script
Args:
- filename: target file (String)
Returns:
- True if success to save (Bool)
"""
session = ""
if not filename:
filename = self.get_config_filename("session")
# exec-wrapper
out = self.execute("show exec-wrapper", to_string=True)
wrapper = out.split('"')[1]
if wrapper:
session += "set exec-wrapper %s\n" % wrapper
try:
# save breakpoints
self.save_breakpoints(filename)
fd = open(filename, "a+")
fd.write("\n" + session)
fd.close()
return True
except:
return False
def restore_session(self, filename=None):
"""
Restore previous saved working gdb session from file
Args:
- filename: source file (String)
Returns:
- True if success to restore (Bool)
"""
if not filename:
filename = self.get_config_filename("session")
# temporarily save and clear breakpoints
tmp = utils.tmpfile()
self.save_breakpoints(tmp.name)
self.execute("delete")
result = self.execute("source %s" % filename)
if not result:
self.execute("source %s" % tmp.name)
tmp.close()
return result
@memoized
def assemble(self, asmcode, bits=None):
"""
Assemble ASM instructions using NASM
- asmcode: input ASM instructions, multiple instructions are separated by ";" (String)
Returns:
- bin code (raw bytes)
"""
if bits is None:
(arch, bits) = self.getarch()
return Nasm.assemble(asmcode, bits)
def disassemble(self, *arg):
"""
Wrapper for disassemble command
- arg: args for disassemble command
Returns:
- text code (String)
"""
code = ""
modif = ""
arg = list(arg)
if len(arg) > 1:
if "/" in arg[0]:
modif = arg[0]
arg = arg[1:]
if len(arg) == 1 and to_int(arg[0]) is not None:
arg += [to_hex(to_int(arg[0]) + 32)]
self.execute("set disassembly-flavor intel")
out = self.execute("disassemble %s %s" % (modif, ",".join(arg)), to_string=True)
if not out:
return None
else:
code = out
return code
@memoized
def prev_inst(self, address, count=1):
"""
Get previous instructions at an address
Args:
- address: address to get previous instruction (Int)
- count: number of instructions to read (Int)
Returns:
- list of tuple (address(Int), code(String))
"""
result = []
backward = 64 + 16 * count
for i in range(backward):
if self.getpid() and not self.is_address(address - backward + i):
continue
code = self.execute("disassemble %s, %s" % (to_hex(address - backward + i), to_hex(address + 1)),
to_string=True)
if code and ("%x" % address) in code:
lines = code.strip().splitlines()[1:-1]
if len(lines) > count and all(["(bad)" not in _l for _l in lines]):
for line in lines[-count - 1:-1]:
try:
(addr, code) = line.split(":", 1)
except ValueError:
warning_msg('asm code error at {:#x}, line: {}'.format(address, line))
continue
addr = re.search("(0x\S+)", addr).group(1)
result += [(to_int(addr), code)]
return result
return None
@memoized
def current_inst(self, address):
"""
Parse instruction at an address
Args:
- address: address to get next instruction (Int)
Returns:
- tuple of (address(Int), code(String))
"""
out = self.execute("x/i %#x" % address, to_string=True)
if not out:
return None
(addr, code) = out.split(":", 1)
addr = re.search("(0x\S+)", addr).group(1)
addr = to_int(addr)
code = code.strip()
return (addr, code)
@memoized
def next_inst(self, address, count=1):
"""
Get next instructions at an address
Args:
- address: address to get next instruction (Int)
- count: number of instructions to read (Int)
Returns:
- - list of tuple (address(Int), code(String))
"""
result = []
code = self.execute("x/%di %#x" % (count + 1, address), to_string=True)
if not code:
return None
lines = code.strip().splitlines()
for i in range(1, count + 1):
if ":" not in lines[i]:
i += 1
(addr, code) = lines[i].split(":", 1)
addr = re.search("(0x\S+)", addr).group(1)
result += [(to_int(addr), code)]
return result
@memoized
def disassemble_around(self, address, count=8):
"""
Disassemble instructions nearby current PC or an address
Args:
- address: start address to disassemble around (Int)
- count: number of instructions to disassemble
Returns:
- text code (String)
"""
count = min(count, 256)
pc = address
if pc is None:
return None
# check if address is reachable
if self.read_int(pc) is None:
return None
prev_code = self.prev_inst(pc, count // 2 - 1)
if prev_code:
start = prev_code[0][0]
else:
start = pc
if start == pc:
count = count // 2
code = self.execute("x/%di %#x" % (count, start), to_string=True)
if "%#x" % pc not in code:
code = self.execute("x/%di %#x" % (count // 2, pc), to_string=True)
return code.rstrip()
@memoized
def xrefs(self, search="", filename=None):
"""
Search for all call references or data access to a function/variable
Args:
- search: function or variable to search for (String)
- filename: binary/library to search (String)
Returns:
- list of tuple (address(Int), asm instruction(String))
"""
result = []
if not filename:
filename = self.getfile()
if not filename:
return None
vmap = self.get_vmmap(filename)
elfbase = vmap[0][0] if vmap else 0
if to_int(search) is not None:
search = "%x" % to_int(search)
search_data = 1
if search == "":
search_data = 0
out = utils.execute_external_command("%s -M intel -z --prefix-address -d '%s' | grep '%s'" %
(config.OBJDUMP, filename, search))
for line in out.splitlines():
if not line: continue
addr = to_int("0x" + line.split()[0].strip())
if not addr: continue
# update with runtime values
if addr < elfbase:
addr += elfbase
out = self.execute("x/i %#x" % addr, to_string=True)
if out:
line = out
m = re.search("\s*(0x\S+).*?:\s*([^ ]*)\s*(.*)", line)
else:
m = re.search("(.*?)\s*<.*?>\s*([^ ]*)\s*(.*)", line)
if m:
(address, opcode, opers) = m.groups()
if "call" in opcode and search in opers:
result += [(addr, line.strip())]
if search_data:
if "mov" in opcode and search in opers:
result += [(addr, line.strip())]
return result
def _get_function_args_32(self, code, argc=None):
"""
Guess the number of arguments passed to a function - i386
"""
if not argc:
argc = 0
matches = re.findall(".*mov.*\[esp(.*)\],", code)
if matches:
l = len(matches)
for v in matches:
if v.startswith("+"):
offset = to_int(v[1:])
if offset is not None and (offset // 4) > l:
continue
argc += 1
else: # try with push style
argc = code.count("push")
argc = min(argc, 6)
if argc == 0:
return []
args = []
sp = self.getreg("sp")
for i in range(argc):
args.append(self.read_int(sp + i * 4, 4))
return args
def _get_function_args_64(self, code, argc=None):
"""
Guess the number of arguments passed to a function - x86_64
"""
# just retrieve max 6 args
arg_order = ["rdi", "rsi", "rdx", "rcx", "r8", "r9"]
matches = re.findall(":\s*([^ ]*)\s*(.*),", code)
regs = [r for (_, r) in matches]
m = re.findall(("di|si|dx|cx|r8|r9"), " ".join(regs))
m = list(set(m)) # uniqify
argc = 0
if "si" in m and "di" not in m: # dirty fix
argc += 1
argc += m.count("di")
if argc > 0:
argc += m.count("si")
if argc > 1:
argc += m.count("dx")
if argc > 2:
argc += m.count("cx")
if argc > 3:
argc += m.count("r8")
if argc > 4:
argc += m.count("r9")
if argc == 0:
return []
args = []
regs = self.getregs()
for i in range(argc):
args += [regs[arg_order[i]]]
return args
def _get_function_args_arm(self, code, argc=None):
"""
Guess the number of arguments passed to a function - aarch64
"""
# just retrieve max 6 args
arg_order = ["r0", "r1", "r2", "r3", "r4", "r5"]
matches = re.findall(":\s*([^\s]*)\s*([^,]*)", code)
regs = [r for (_, r) in matches]
m = re.findall("(r[0-5])", " ".join(regs))
m = list(set(m)) # uniqify
argc = 0
if "r1" in m and "r0" not in m: # dirty fix
argc += 1
argc += m.count("r0")
if argc > 0:
argc += m.count("r1")
if argc > 1:
argc += m.count("r2")
if argc > 2:
argc += m.count("r3")
if argc > 3:
argc += m.count("r4")
if argc > 4:
argc += m.count("r5")
if argc == 0:
return []
args = []
regs = self.getregs()
for i in range(argc):
args += [regs[arg_order[i]]]
return args
def _get_function_args_aarch64(self, code, argc=None):
"""
Guess the number of arguments passed to a function - aarch64