def test_sha3_key(self):
"""Exercise solidity-like mappings, with the key being a sha3."""
state = State(self.env)
state_write = state.copy()
# Arbitrary write input[1], at SHA3(input[0])
state_write.storage_written = {
Sha3(self.env.calldata.read(4, 32)): self.env.calldata.read(36, 32)
}
# Needs that: storage[SHA3(input[0])] == 43, made possible by the previous call
state_selfdestruct = state.copy()
state_selfdestruct.selfdestruct_to = self.env.calldata.read(36, 32)
storage_input = claripy.BVS("storage[SHA3(input)]", 256)
state_selfdestruct.storage_read = {
Sha3(self.env.calldata.read(4, 32)): storage_input
}
state_selfdestruct.solver.add(storage_input == 0xDEADBEEF101010)
storage = {
55186156870478567193644641351382124067713781048612400765092754877653207859685: 0
}
self.assertTrue(
self.check_states([state_write, state_selfdestruct], mock_storage=storage)
)
self.assertFalse(self.check_states([state_selfdestruct], mock_storage=storage))
self.assertFalse(self.check_states([state_write]))
def test_solver_copy(self):
s = get_solver()
in1 = claripy.BVS("in1", 256)
s.add(Sha3(in1) == 0)
self.assertFalse(s.satisfiable())
s2 = s.branch()
self.assertFalse(s2.satisfiable())
def test_sha3_value2(self):
"""Same as above, but we need to pass the computed SHA3."""
state = State(self.env)
state_write = state.copy()
state_write.storage_written = {
utils.bvv(0): Sha3(self.env.calldata.read(4, 32))
}
state_selfdestruct = state.copy()
state_selfdestruct.selfdestruct_to = self.env.calldata.read(36, 32)
storage_input = claripy.BVS("storage[0]", 256)
state_selfdestruct.storage_read = {utils.bvv(0): storage_input}
state_selfdestruct.solver.add(
storage_input == self.env.calldata.read(4, 32))
state_selfdestruct.solver.add(storage_input != 0)
storage = {0: 0}
self.assertTrue(
self.check_states([state_write, state_selfdestruct],
mock_storage=storage))
self.assertFalse(
self.check_states([state_selfdestruct], mock_storage=storage))
self.assertFalse(self.check_states([state_write],
mock_storage=storage))
def test_cannot_combine(self):
"""If we didn't do a replace(), we cannot combine the same thing."""
s = get_solver()
a = claripy.BVS("a", 256)
s.add(Sha3(a) == 8)
s2 = s.branch()
with self.assertRaises(ValueError):
s.combine([s2])
def test_solver_one_var(self):
s = get_solver()
in1 = claripy.BVS("in1", 256)
self.assertFalse(s.satisfiable(extra_constraints=[Sha3(in1) == 42]))
self.assertFalse(s.satisfiable(extra_constraints=[Sha3(in1) == 0]))
self.assertTrue(s.satisfiable(extra_constraints=[Sha3(in1) == Sha3(bvv(42))]))
self.assertTrue(s.satisfiable(extra_constraints=[Sha3(in1) == Sha3(bvv(0))]))
self.assertTrue(
s.satisfiable(extra_constraints=[Sha3(in1 + 1) + 2 == Sha3(bvv(0)) + 2])
)
def test_env_replace_merge_with_recursive_hash(self):
old_env = env.Env(b"")
new_env = old_env.clean_copy()
old_state = State(old_env)
old_state.solver.add(Sha3(Sha3(old_env.caller)) == Sha3(old_env.value))
self.assertTrue(old_state.solver.satisfiable())
self.assertFalse(
old_state.solver.satisfiable(
extra_constraints=[old_env.value == 5]))
new_state = old_state.copy()
new_state.replace(functools.partial(env.replace, old_env, new_env))
new_state.replace(new_state.solver.regenerate_hash_symbols())
self.assertTrue(new_state.solver.satisfiable())
self.assertFalse(
new_state.solver.satisfiable(
extra_constraints=[new_env.value == 5]))
self.assertTrue(
new_state.solver.satisfiable(
extra_constraints=[old_env.value == 5]))
new_state.solver.add(old_env.value == new_env.value)
self.assertTrue(new_state.solver.satisfiable())
self.assertFalse(
new_state.solver.satisfiable(
extra_constraints=[new_env.value == 5]))
self.assertFalse(
new_state.solver.satisfiable(
extra_constraints=[old_env.value == 5]))
old_state.solver = old_state.solver.combine([new_state.solver])
self.assertTrue(new_state.solver.satisfiable())
self.assertEqual(len(old_state.solver.constraints), 3)
self.assertEqual(len(old_state.solver.hashes),
len(new_state.solver.hashes) * 2)
def test_sha3_value1(self):
"""Exercise comparison of two SHA3 (as values)."""
state = State(self.env)
state_write = state.copy()
state_write.storage_written = {
utils.bvv(0): Sha3(self.env.calldata.read(4, 32))
}
state_selfdestruct = state.copy()
state_selfdestruct.selfdestruct_to = self.env.calldata.read(36, 32)
storage_input = claripy.BVS("storage[0]", 256)
state_selfdestruct.storage_read = {utils.bvv(0): storage_input}
state_selfdestruct.solver.add(
storage_input == Sha3(self.env.calldata.read(4, 32))
)
storage = {0: 0}
self.assertTrue(
self.check_states([state_write, state_selfdestruct], mock_storage=storage)
)
self.assertFalse(self.check_states([state_selfdestruct], mock_storage=storage))
self.assertFalse(self.check_states([state_write], mock_storage=storage))
def test_solver_recursive(self):
s = get_solver()
in1 = claripy.BVS("in1", 256)
in2 = claripy.BVS("in2", 256)
self.assertFalse(
s.satisfiable(extra_constraints=[Sha3(Sha3(in1)) == 0]))
self.assertFalse(
s.satisfiable(extra_constraints=[Sha3(Sha3(in1)) == Sha3(0)]))
self.assertTrue(
s.satisfiable(
extra_constraints=[Sha3(Sha3(in1)) == Sha3(Sha3(0))]))
s.add(Sha3(in1) == Sha3(in2))
self.assertTrue(s.satisfiable())
self.assertTrue(
s.satisfiable(
extra_constraints=[Sha3(Sha3(in1) + 1) == Sha3(Sha3(in2) +
1)]))
s.add(Sha3(Sha3(in1) + 1) == Sha3(Sha3(in2) + 1))
self.assertTrue(s.satisfiable())
self.assertFalse(
s.satisfiable(
extra_constraints=[Sha3(Sha3(in1) + 2) == Sha3(Sha3(in2) +
1)]))
self.assertFalse(
s.satisfiable(
extra_constraints=[Sha3(Sha3(in1)) + 1 == Sha3(Sha3(in2) +
1)]))
s.add(Sha3(Sha3(in1)) + 3 == Sha3(Sha3(in2)) + 1)
self.assertFalse(s.satisfiable())
s_copy = s.branch()
self.assertFalse(s_copy.satisfiable())
def test_solver_arithmetics(self):
s = get_solver()
in1 = claripy.BVS("in1", 256)
in2 = claripy.BVS("in2", 256)
self.assertTrue(
s.satisfiable(extra_constraints=[Sha3(in1) + 1 == Sha3(in2) + 1]))
self.assertFalse(
s.satisfiable(extra_constraints=[Sha3(in1) + 1 == Sha3(in2) + 2]))
self.assertFalse(
s.satisfiable(extra_constraints=[Sha3(in1) + 1 == Sha3(in2) + 2]))
self.assertTrue(
s.satisfiable(extra_constraints=[Sha3(in1 + 1) == Sha3(in2 + 1)]))
self.assertTrue(
s.satisfiable(extra_constraints=[Sha3(in1 + 1) == Sha3(in2 - 1)]))
self.assertFalse(
s.satisfiable(
extra_constraints=[Sha3(in1 + 1) + 42 == Sha3(in2 - 1)]))
def test_solver_basic(self):
s = get_solver()
in1 = claripy.BVS("in1", 256)
in2 = claripy.BVS("in2", 256)
self.assertTrue(
s.satisfiable(extra_constraints=[Sha3(in1) == Sha3(in2)]))
self.assertTrue(
s.satisfiable(extra_constraints=[Sha3(in1) != Sha3(in2)]))
# These next two always hold anyway.
self.assertTrue(
s.satisfiable(extra_constraints=[Sha3(in1) + 1 != Sha3(in2)]))
self.assertFalse(
s.satisfiable(extra_constraints=[Sha3(in1) + 1 == Sha3(in2)]))
s.add(in1 == in2)
self.assertTrue(
s.satisfiable(extra_constraints=[Sha3(in1) == Sha3(in2)]))
self.assertFalse(
s.satisfiable(extra_constraints=[Sha3(in1) != Sha3(in2)]))
# These next two always hold anyway.
self.assertTrue(
s.satisfiable(extra_constraints=[Sha3(in1) + 1 != Sha3(in2)]))
self.assertFalse(
s.satisfiable(extra_constraints=[Sha3(in1) + 1 == Sha3(in2)]))
s = get_solver()
s.add(in1 != in2)
self.assertFalse(
s.satisfiable(extra_constraints=[Sha3(in1) == Sha3(in2)]))
self.assertTrue(
s.satisfiable(extra_constraints=[Sha3(in1) != Sha3(in2)]))
# These next two always hold anyway.
self.assertTrue(
s.satisfiable(extra_constraints=[Sha3(in1) + 1 != Sha3(in2)]))
self.assertFalse(
s.satisfiable(extra_constraints=[Sha3(in1) + 1 == Sha3(in2)]))
def exec_branch(self, state): # pylint:disable=invalid-name
"""Execute forward from a state, queuing new states if needed."""
logger.debug("Constraints: %s", state.solver.constraints)
def solution(variable):
"""Returns the solution. There must be one or we fail."""
solutions = state.solver.eval(variable, 2)
if len(solutions) > 1:
raise MultipleSolutionsError(
"Multiple solutions for %s (%#x)" %
(variable, self.code[state.pc]))
solution = solutions[0]
return solution if isinstance(solution,
numbers.Number) else solution.value
self.code.pc = state.pc
while True:
if state.pc >= len(self.code):
return True
op = self.code[state.pc]
self.code.pc += 1
self.coverage[state.pc] += 1
logger.debug("NEW STEP")
logger.debug("Memory: %s", state.memory)
logger.debug("Stack: %s", state.stack)
logger.debug("PC: %i, %#x", state.pc, op)
assert self.code.pc == state.pc + 1
assert isinstance(op, numbers.Number)
assert all(
isinstance(i, claripy.ast.base.BV) for i in
state.stack), "The stack musty only contains claripy BV's"
# Trivial operations first
if not self.code.is_valid_opcode(state.pc):
raise utils.CodeError("Trying to execute PUSH data")
elif op == 254: # INVALID opcode
raise utils.CodeError("designed INVALID opcode")
elif op == opcode_values.JUMPDEST:
pass
elif op == opcode_values.ADD:
s0, s1 = (
state.stack_pop(),
state.stack_pop(),
) # pylint:disable=invalid-name
state.stack_push(s0 + s1)
elif op == opcode_values.SUB:
s0, s1 = (
state.stack_pop(),
state.stack_pop(),
) # pylint:disable=invalid-name
state.stack_push(s0 - s1)
elif op == opcode_values.MUL:
s0, s1 = (
state.stack_pop(),
state.stack_pop(),
) # pylint:disable=invalid-name
state.stack_push(s0 * s1)
elif op == opcode_values.DIV:
# We need to use claripy.LShR instead of a division if possible,
# because the solver is bad dealing with divisions, better
# with shifts. And we need shifts to handle the solidity ABI
# for function selection.
s0, s1 = (
state.stack_pop(),
state.stack_pop(),
) # pylint:disable=invalid-name
try:
s1 = solution(s1) # pylint:disable=invalid-name
except MultipleSolutionsError:
state.stack_push(claripy.If(s1 == 0, BVV_0, s0 / s1))
else:
if s1 == 0:
state.stack_push(BVV_0)
elif s1 == 1:
state.stack_push(s0)
elif s1 & (s1 - 1) == 0:
exp = int(math.log(s1, 2))
state.stack_push(s0.LShR(exp))
else:
state.stack_push(s0 / s1)
elif op == opcode_values.SDIV:
s0, s1 = (
state.stack_pop(),
state.stack_pop(),
) # pylint:disable=invalid-name
try:
s1 = solution(s1)
except MultipleSolutionsError:
state.stack_push(claripy.If(s1 == 0, BVV_0, s0.SDiv(s1)))
else:
state.stack_push(BVV_0 if s1 == 0 else s0.SDiv(s1))
elif op == opcode_values.MOD:
s0, s1 = (
state.stack_pop(),
state.stack_pop(),
) # pylint:disable=invalid-name
try:
s1 = solution(s1)
except MultipleSolutionsError:
state.stack_push(claripy.If(s1 == 0, BVV_0, s0 % s1))
else:
state.stack_push(BVV_0 if s1 == 0 else s0 % s1)
elif op == opcode_values.SMOD:
s0, s1 = (
state.stack_pop(),
state.stack_pop(),
) # pylint:disable=invalid-name
try:
s1 = solution(s1)
except MultipleSolutionsError:
state.stack_push(claripy.If(s1 == 0, BVV_0, s0.SMod(s1)))
else:
state.stack_push(BVV_0 if s1 == 0 else s0.SMod(s1))
elif op == opcode_values.ADDMOD:
s0, s1, s2 = state.stack_pop(), state.stack_pop(
), state.stack_pop()
try:
s2 = solution(s2)
except MultipleSolutionsError:
state.stack_push(claripy.If(s2 == 0, BVV_0,
(s0 + s1) % s2))
else:
state.stack_push(BVV_0 if s2 == 0 else (s0 + s1) % s2)
elif op == opcode_values.MULMOD:
s0, s1, s2 = state.stack_pop(), state.stack_pop(
), state.stack_pop()
try:
s2 = solution(s2)
except MultipleSolutionsError:
state.stack_push(claripy.If(s2 == 0, BVV_0,
(s0 * s1) % s2))
else:
state.stack_push(BVV_0 if s2 == 0 else (s0 * s1) % s2)
elif op == opcode_values.SHL:
shift, value = state.stack_pop(), state.stack_pop()
state.stack_push(value << shift)
elif op == opcode_values.SHR:
shift, value = state.stack_pop(), state.stack_pop()
state.stack_push(value.LShR(shift))
elif op == opcode_values.SAR:
shift, value = state.stack_pop(), state.stack_pop()
state.stack_push(claripy.RotateRight(value, shift))
elif op == opcode_values.EXP:
base, exponent = state.stack_pop(), state.stack_pop()
base_sol = solution(base)
if base_sol == 2:
state.stack_push(1 << exponent)
else:
try:
exponent_sol = solution(exponent)
except MultipleSolutionsError:
state.stack_push(exponent) # restore stack
state.stack_push(base)
self.add_for_fuzzing(state, exponent,
EXP_EXPONENT_FUZZ)
return False
else:
state.stack_push(
claripy.BVV(base_sol**exponent_sol, 256))
elif op == opcode_values.LT:
s0, s1 = (
state.stack_pop(),
state.stack_pop(),
) # pylint:disable=invalid-name
state.stack_push(bool_to_bv(claripy.ULT(s0, s1)))
elif op == opcode_values.GT:
s0, s1 = (
state.stack_pop(),
state.stack_pop(),
) # pylint:disable=invalid-name
state.stack_push(bool_to_bv(claripy.UGT(s0, s1)))
elif op == opcode_values.SLT:
s0, s1 = (
state.stack_pop(),
state.stack_pop(),
) # pylint:disable=invalid-name
state.stack_push(bool_to_bv(claripy.SLT(s0, s1)))
elif op == opcode_values.SGT:
s0, s1 = (
state.stack_pop(),
state.stack_pop(),
) # pylint:disable=invalid-name
state.stack_push(bool_to_bv(claripy.SGT(s0, s1)))
elif op == opcode_values.SIGNEXTEND:
# TODO: Use Claripy's SignExt that should do exactly that.
s0, s1 = (
state.stack_pop(),
state.stack_pop(),
) # pylint:disable=invalid-name
# s0 is the number of bits. s1 the number we want to extend.
s0 = solution(s0)
if s0 <= 31:
sign_bit = 1 << (s0 * 8 + 7)
state.stack_push(
claripy.If(
s1 & sign_bit == 0,
s1 & (sign_bit - 1),
s1 | ((1 << 256) - sign_bit),
))
else:
state.stack_push(s1)
elif op == opcode_values.EQ:
s0, s1 = state.stack_pop(), state.stack_pop()
state.stack_push(bool_to_bv(s0 == s1))
elif op == opcode_values.ISZERO:
state.stack_push(bool_to_bv(state.stack_pop() == BVV_0))
elif op == opcode_values.AND:
s0, s1 = state.stack_pop(), state.stack_pop()
state.stack_push(s0 & s1)
elif op == opcode_values.OR:
s0, s1 = state.stack_pop(), state.stack_pop()
state.stack_push(s0 | s1)
elif op == opcode_values.XOR:
s0, s1 = state.stack_pop(), state.stack_pop()
state.stack_push(s0 ^ s1)
elif op == opcode_values.NOT:
state.stack_push(~state.stack_pop())
elif op == opcode_values.BYTE:
s0, s1 = (
state.stack_pop(),
state.stack_pop(),
) # pylint:disable=invalid-name
state.stack_push(
s1.LShR(claripy.If(s0 > 31, 32, 31 - s0) * 8) & 0xFF)
elif op == opcode_values.PC:
state.stack_push(bvv(state.pc))
elif op == opcode_values.GAS:
state.stack_push(state.env.gas)
elif op == opcode_values.ADDRESS:
state.stack_push(state.env.address)
elif op == opcode_values.BALANCE:
addr = solution(state.stack_pop())
if addr != solution(state.env.address):
raise utils.InterpreterError(
state,
"Can only query balance of the current contract for now"
)
state.stack_push(state.env.balance)
elif op == opcode_values.ORIGIN:
state.stack_push(state.env.origin)
elif op == opcode_values.CALLER:
state.stack_push(state.env.caller)
elif op == opcode_values.CALLVALUE:
state.stack_push(state.env.value)
elif op == opcode_values.BLOCKHASH:
block_num = state.stack_pop()
if block_num not in state.env.block_hashes:
state.env.block_hashes[block_num] = claripy.BVS(
"blockhash[%s]" % block_num, 256)
state.stack_push(state.env.block_hashes[block_num])
elif op == opcode_values.TIMESTAMP:
state.stack_push(state.env.block_timestamp)
elif op == opcode_values.NUMBER:
state.stack_push(state.env.block_number)
elif op == opcode_values.COINBASE:
state.stack_push(state.env.coinbase)
elif op == opcode_values.DIFFICULTY:
state.stack_push(state.env.difficulty)
elif op == opcode_values.POP:
state.stack_pop()
elif op == opcode_values.JUMP:
addr = solution(state.stack_pop())
if addr >= len(self.code
) or self.code[addr] != opcode_values.JUMPDEST:
raise utils.CodeError("Invalid jump (%i)" % addr)
state.pc = addr
self.add_branch(state)
return False
elif op == opcode_values.JUMPI:
addr, condition = solution(
state.stack_pop()), state.stack_pop()
state_false = state.copy()
state.solver.add(condition != BVV_0)
state_false.solver.add(condition == BVV_0)
state_false.pc += 1
self.add_branch(state_false)
state.pc = addr
if (state.pc >= len(self.code)
or self.code[state.pc] != opcode_values.JUMPDEST):
raise utils.CodeError("Invalid jump (%i)" % (state.pc - 1))
self.add_branch(state)
return False
elif opcode_values.PUSH1 <= op <= opcode_values.PUSH32:
pushnum = op - opcode_values.PUSH1 + 1
raw_value = self.code.read(pushnum)
state.pc += pushnum
state.stack_push(
bvv(int.from_bytes(raw_value, byteorder="big")))
elif opcode_values.DUP1 <= op <= opcode_values.DUP16:
depth = op - opcode_values.DUP1 + 1
state.stack_push(state.stack[-depth])
elif opcode_values.SWAP1 <= op <= opcode_values.SWAP16:
depth = op - opcode_values.SWAP1 + 1
temp = state.stack[-depth - 1]
state.stack[-depth - 1] = state.stack[-1]
state.stack[-1] = temp
elif opcode_values.LOG0 <= op <= opcode_values.LOG4:
depth = op - opcode_values.LOG0
mstart, msz = (state.stack_pop(), state.stack_pop())
topics = [state.stack_pop() for x in range(depth)]
elif op == opcode_values.SHA3:
start, length = solution(state.stack_pop()), solution(
state.stack_pop())
memory = state.memory.read(start, length)
state.stack_push(Sha3(memory))
elif op == opcode_values.STOP:
return True
elif op == opcode_values.RETURN:
return True
elif op == opcode_values.CALLDATALOAD:
index = state.stack_pop()
try:
index_sol = solution(index)
except MultipleSolutionsError:
state.stack_push(index) # restore the stack
self.add_for_fuzzing(state, index, CALLDATALOAD_INDEX_FUZZ)
return False
state.stack_push(state.env.calldata.read(index_sol, 32))
elif op == opcode_values.CALLDATASIZE:
state.stack_push(state.env.calldata_size)
elif op == opcode_values.CALLDATACOPY:
old_state = state.copy()
mstart, dstart, size = (
state.stack_pop(),
state.stack_pop(),
state.stack_pop(),
)
mstart, dstart = solution(mstart), solution(dstart)
try:
size = solution(size)
except MultipleSolutionsError:
self.add_for_fuzzing(old_state, size,
CALLDATACOPY_SIZE_FUZZ)
return False
state.memory.copy_from(state.env.calldata, mstart, dstart,
size)
elif op == opcode_values.CODESIZE:
state.stack_push(bvv(len(self.code)))
elif op == opcode_values.EXTCODESIZE:
addr = state.stack_pop()
if (addr == state.env.address).is_true():
state.stack_push(bvv(len(self.code)))
else:
# TODO: Improve that... It's clearly not constraining enough.
state.stack_push(claripy.BVS("EXTCODESIZE[%s]" % addr,
256))
elif op == opcode_values.EXTCODECOPY:
old_state = state.copy()
addr = state.stack_pop()
mem_start = solution(state.stack_pop())
code_start = solution(state.stack_pop())
size = state.stack_pop()
try:
size = solution(size)
except MultipleSolutionsError:
# TODO: Fuzz.
# self.add_for_fuzzing(old_state, size, [])
# return False
raise
state.memory.write(
mem_start,
size,
claripy.BVS("EXTCODE[%s from %s]" % (addr, code_start),
size * 8),
)
elif op == opcode_values.CODECOPY:
mem_start, code_start, size = [
solution(state.stack_pop()) for _ in range(3)
]
for i in range(size):
if code_start + i < len(state.env.code):
state.memory.write(
mem_start + i,
1,
claripy.BVV(state.env.code[code_start + i], 8),
)
else:
state.memory.write(mem_start + i, 1, claripy.BVV(0, 8))
elif op == opcode_values.MLOAD:
index = solution(state.stack_pop())
state.stack_push(state.memory.read(index, 32))
elif op == opcode_values.MSTORE:
index, value = solution(state.stack_pop()), state.stack_pop()
state.memory.write(index, 32, value)
elif op == opcode_values.MSTORE8:
index, value = solution(state.stack_pop()), state.stack_pop()
state.memory.write(index, 1, value[7:0])
elif op == opcode_values.MSIZE:
state.stack_push(bvv(state.memory.size()))
elif op == opcode_values.SLOAD:
state.pc += 1
key = state.stack_pop()
for w_key, w_value in state.storage_written.items():
read_written = [w_key == key]
if state.solver.satisfiable(
extra_constraints=read_written):
new_state = state.copy()
new_state.solver.add(read_written)
new_state.stack_push(w_value)
self.add_branch(new_state)
state.solver.add(w_key != key)
if state.solver.satisfiable():
assert key not in state.storage_written
if key not in state.storage_read:
state.storage_read[key] = claripy.BVS(
"storage[%s]" % key, 256)
state.stack_push(state.storage_read[key])
self.add_branch(state)
return
elif op == opcode_values.SSTORE:
state.pc += 1
key = state.stack_pop()
value = state.stack_pop()
for w_key, w_value in state.storage_written.items():
read_written = [w_key == key]
if state.solver.satisfiable(
extra_constraints=read_written):
new_state = state.copy()
new_state.solver.add(read_written)
new_state.storage_written[w_key] = value
self.add_branch(new_state)
state.solver.add(w_key != key)
if state.solver.satisfiable():
assert key not in state.storage_written
state.storage_written[key] = value
self.add_branch(state)
return
elif op == opcode_values.CALL:
state.pc += 1
# pylint:disable=unused-variable
gas, to_, value, meminstart, meminsz, memoutstart, memoutsz = (
state.stack_pop() for _ in range(7))
# First possibility: the call fails
# (always possible with a call stack big enough)
state_fail = state.copy()
state_fail.stack_push(BVV_0)
self.add_branch(state_fail)
# Second possibility: success.
state.calls.append((memoutsz, memoutstart, meminsz, meminstart,
value, to_, gas))
memoutsz = solution(memoutsz)
if memoutsz != 0:
# If we expect some output, let's constraint the call to
# be to a contract that we do control. Otherwise it could
# return anything...
state.solver.add(to_[159:0] == utils.DEFAULT_CALLER[159:0])
memoutstart = solution(memoutstart)
state.memory.write(
memoutstart,
memoutsz,
claripy.BVS("CALL_RETURN[%s]" % to_, memoutsz * 8),
)
state.stack_push(BVV_1)
self.add_branch(state)
return False
elif op == opcode_values.DELEGATECALL:
state.pc += 1
# pylint:disable=unused-variable
gas, to_, meminstart, meminsz, memoutstart, memoutsz = (
state.stack_pop() for _ in range(6))
# First possibility: the call fails
# (always possible with a call stack big enough)
state_fail = state.copy()
state_fail.stack_push(BVV_0)
self.add_branch(state_fail)
# If the call is to a specific contract we don't control,
# don't assume it could return anything, or even be successful.
# So we say we need to be able to call an arbitrary contract.
state.solver.add(to_[159:0] == utils.DEFAULT_CALLER[159:0])
# Second possibility: success.
state.calls.append(
(memoutsz, memoutstart, meminsz, meminstart, to_, gas))
memoutsz = solution(memoutsz)
if memoutsz != 0:
memoutstart = solution(memoutstart)
state.memory.write(
memoutstart,
memoutsz,
claripy.BVS("DELEGATECALL_RETURN[%s]" % to_,
memoutsz * 8),
)
state.stack_push(BVV_1)
self.add_branch(state)
return False
elif op == opcode_values.RETURNDATASIZE:
state.stack_push(claripy.BVS("RETURNDATASIZE", 256))
elif op == opcode_values.RETURNDATACOPY:
old_state = state.copy()
mem_start_position = solution(state.stack_pop())
returndata_start_position = solution(state.stack_pop())
size = state.stack_pop()
try:
size = solution(size)
except MultipleSolutionsError:
self.add_for_fuzzing(old_state, size,
RETURNDATACOPY_SIZE_FUZZ)
return False
state.memory.write(mem_start_position, size,
claripy.BVS("RETURNDATACOPY", size * 8))
elif op == opcode_values.SELFDESTRUCT:
state.selfdestruct_to = state.stack[-1]
return True
elif op == opcode_values.REVERT:
return False
else:
raise utils.InterpreterError(state, "Unknown opcode %#x" % op)
state.pc += 1
def test_sha3_equality(self):
a = claripy.BVV(1, 256)
b = claripy.BVV(2, 256)
self.assertEqual(Sha3(a), Sha3(claripy.BVV(1, 256)))
self.assertNotEqual(Sha3(a), Sha3(b))
def test_solver_recursive_unbalanced(self):
s = get_solver()
in1 = claripy.BVS("in1", 256)
in2 = claripy.BVS("in2", 256)
self.assertFalse(
s.satisfiable(extra_constraints=[Sha3(Sha3(in1)) == Sha3(bvv(0))])
)
self.assertTrue(s.satisfiable(extra_constraints=[Sha3(Sha3(in1)) == Sha3(in2)]))
logging.debug("here")
self.assertTrue(s.satisfiable(extra_constraints=[Sha3(in1) == Sha3(Sha3(in2))]))
self.assertTrue(
s.satisfiable(extra_constraints=[Sha3(Sha3(Sha3(in1))) == Sha3(in2)])
)
self.assertTrue(
s.satisfiable(extra_constraints=[Sha3(in1) == Sha3(Sha3(Sha3(in2)))])
)
def test_solver_three_symbols(self):
s = get_solver()
in1 = claripy.BVS("in1", 256)
in2 = claripy.BVS("in2", 256)
in3 = claripy.BVS("in2", 256)
self.assertFalse(
s.satisfiable(
extra_constraints=[Sha3(in1) == Sha3(Sha3(in3)) + Sha3(Sha3(Sha3(in2)))]
)
)
self.assertTrue(
s.satisfiable(
extra_constraints=[in1 == Sha3(Sha3(in3)) + Sha3(Sha3(Sha3(in2)))]
)
)
def exec_branch(self, state): # pylint:disable=invalid-name
"""Execute forward from a state, queuing new states if needed."""
logger.debug("Constraints: %s", state.solver.constraints)
def solution(variable):
"""Returns the solution. There must be one or we fail."""
solutions = state.solver.eval(variable, 2)
if len(solutions) > 1:
raise ValueError("Ambiguous solution for %s (%s)" %
(variable, self.code[state.pc]))
solution = solutions[0]
return solution if isinstance(solution,
numbers.Number) else solution.value
state.score += 1
self.code.pc = state.pc
while True:
if state.pc >= len(self.code):
return True
op = self.code.next()
self.coverage[state.pc] += 1
logger.debug("NEW STEP")
logger.debug("Memory: %s", state.memory)
logger.debug("Stack: %s", state.stack)
logger.debug("PC: %i, %s", state.pc, op)
assert self.code.pc == state.pc + 1
assert isinstance(op, numbers.Number)
assert all(
hasattr(i, "symbolic") for i in
state.stack), "The stack musty only contains claripy BV's"
# Trivial operations first
if not self.code.is_valid_opcode(state.pc):
raise utils.CodeError("Trying to execute PUSH data")
elif op == 254: # INVALID opcode
raise utils.CodeError("designed INVALID opcode")
elif op == opcode_values.JUMPDEST:
pass
elif op == opcode_values.ADD:
s0, s1 = (
not_bool(state.stack_pop()),
not_bool(state.stack_pop()),
) # pylint:disable=invalid-name
state.stack_push(s0 + s1)
elif op == opcode_values.SUB:
s0, s1 = (
not_bool(state.stack_pop()),
not_bool(state.stack_pop()),
) # pylint:disable=invalid-name
state.stack_push(s0 - s1)
elif op == opcode_values.MUL:
s0, s1 = (
not_bool(state.stack_pop()),
not_bool(state.stack_pop()),
) # pylint:disable=invalid-name
state.stack_push(s0 * s1)
elif op == opcode_values.DIV:
# We need to use claripy.LShR instead of a division if possible,
# because the solver is bad dealing with divisions, better
# with shifts. And we need shifts to handle the solidity ABI
# for function selection.
s0, s1 = (
state.stack_pop(),
state.stack_pop(),
) # pylint:disable=invalid-name
try:
s1 = solution(s1) # pylint:disable=invalid-name
except ValueError:
state.stack_push(claripy.If(s1 == 0, BVV_0, s0 / s1))
else:
if s1 == 0:
state.stack_push(BVV_0)
elif s1 == 1:
state.stack_push(s0)
elif s1 & (s1 - 1) == 0:
exp = int(math.log(s1, 2))
state.stack_push(s0.LShR(exp))
else:
state.stack_push(s0 / s1)
elif op == opcode_values.SDIV:
s0, s1 = (
state.stack_pop(),
state.stack_pop(),
) # pylint:disable=invalid-name
try:
s1 = solution(s1)
except ValueError:
state.stack_push(claripy.If(s1 == 0, BVV_0, s0.SDiv(s1)))
else:
state.stack_push(BVV_0 if s1 == 0 else s0.SDiv(s1))
elif op == opcode_values.MOD:
s0, s1 = (
state.stack_pop(),
state.stack_pop(),
) # pylint:disable=invalid-name
try:
s1 = solution(s1)
except ValueError:
state.stack_push(claripy.If(s1 == 0, BVV_0, s0 % s1))
else:
state.stack_push(BVV_0 if s1 == 0 else s0 % s1)
elif op == opcode_values.SMOD:
s0, s1 = (
state.stack_pop(),
state.stack_pop(),
) # pylint:disable=invalid-name
try:
s1 = solution(s1)
except ValueError:
state.stack_push(claripy.If(s1 == 0, BVV_0, s0.SMod(s1)))
else:
state.stack_push(BVV_0 if s1 == 0 else s0.SMod(s1))
elif op == opcode_values.ADDMOD:
s0, s1, s2 = state.stack_pop(), state.stack_pop(
), state.stack_pop()
try:
s2 = solution(s2)
except ValueError:
state.stack_push(claripy.If(s2 == 0, BVV_0,
(s0 + s1) % s2))
else:
state.stack_push(BVV_0 if s2 == 0 else (s0 + s1) % s2)
elif op == opcode_values.MULMOD:
s0, s1, s2 = state.stack_pop(), state.stack_pop(
), state.stack_pop()
try:
s2 = solution(s2)
except ValueError:
state.stack_push(claripy.If(s2 == 0, BVV_0,
(s0 * s1) % s2))
else:
state.stack_push(BVV_0 if s2 == 0 else (s0 * s1) % s2)
elif op == opcode_values.EXP:
base, exponent = solution(state.stack_pop()), state.stack_pop()
if base == 2:
state.stack_push(1 << exponent)
else:
exponent = solution(exponent)
state.stack_push(claripy.BVV(base**exponent, 256))
elif op == opcode_values.LT:
s0, s1 = (
not_bool(state.stack_pop()),
not_bool(state.stack_pop()),
) # pylint:disable=invalid-name
state.stack_push(claripy.ULT(s0, s1))
elif op == opcode_values.GT:
s0, s1 = (
not_bool(state.stack_pop()),
not_bool(state.stack_pop()),
) # pylint:disable=invalid-name
state.stack_push(claripy.UGT(s0, s1))
elif op == opcode_values.SLT:
s0, s1 = (
not_bool(state.stack_pop()),
not_bool(state.stack_pop()),
) # pylint:disable=invalid-name
state.stack_push(claripy.SLT(s0, s1))
elif op == opcode_values.SGT:
s0, s1 = (
not_bool(state.stack_pop()),
not_bool(state.stack_pop()),
) # pylint:disable=invalid-name
state.stack_push(claripy.SGT(s0, s1))
elif op == opcode_values.SIGNEXTEND:
s0, s1 = (
state.stack_pop(),
state.stack_pop(),
) # pylint:disable=invalid-name
# s0 is the number of bits. s1 the number we want to extend.
s0 = solution(s0)
if s0 <= 31:
sign_bit = 1 << (s0 * 8 + 7)
state.stack_push(
claripy.If(
s1 & sign_bit == 0,
s1 & (sign_bit - 1),
s1 | ((1 << 256) - sign_bit),
))
else:
state.stack_push(s1)
elif op == opcode_values.EQ:
s0, s1 = state.stack_pop(), state.stack_pop()
if isinstance(s0, claripy.ast.Bool) and isinstance(
s1, claripy.ast.Bool):
state.stack_push(s0 == s1)
else:
state.stack_push(not_bool(s0) == not_bool(s1))
elif op == opcode_values.ISZERO:
condition = state.stack_pop()
if isinstance(condition, claripy.ast.Bool):
state.stack_push(claripy.Not(condition))
else:
state.stack_push(condition == BVV_0)
elif op == opcode_values.AND:
s0, s1 = make_consistent(state.stack_pop(), state.stack_pop())
if isinstance(s0, claripy.ast.Bool) and isinstance(
s1, claripy.ast.Bool):
state.stack_push(s0 and s1)
else:
state.stack_push(s0 & s1)
elif op == opcode_values.OR:
s0, s1 = make_consistent(state.stack_pop(), state.stack_pop())
if isinstance(s0, claripy.ast.Bool) and isinstance(
s1, claripy.ast.Bool):
state.stack_push(s0 or s1)
else:
state.stack_push(s0 | s1)
elif op == opcode_values.XOR:
s0, s1 = make_consistent(state.stack_pop(), state.stack_pop())
state.stack_push(s0 ^ s1)
elif op == opcode_values.NOT:
state.stack_push(~state.stack_pop())
elif op == opcode_values.BYTE:
s0, s1 = (
state.stack_pop(),
state.stack_pop(),
) # pylint:disable=invalid-name
state.stack_push(
s1.LShR(claripy.If(s0 > 31, 32, 31 - s0) * 8) & 0xFF)
elif op == opcode_values.PC:
state.stack_push(bvv(state.pc))
elif op == opcode_values.GAS:
state.stack_push(state.env.gas)
elif op == opcode_values.ADDRESS:
state.stack_push(state.env.address)
elif op == opcode_values.BALANCE:
addr = solution(state.stack_pop())
if addr != solution(state.env.address):
raise utils.InterpreterError(
state,
"Can only query balance of the current contract for now"
)
state.stack_push(state.env.balance)
elif op == opcode_values.ORIGIN:
state.stack_push(state.env.origin)
elif op == opcode_values.CALLER:
state.stack_push(state.env.caller)
elif op == opcode_values.CALLVALUE:
state.stack_push(state.env.value)
elif op == opcode_values.BLOCKHASH:
block_num = state.stack_pop()
if block_num not in state.env.block_hashes:
state.env.block_hashes[block_num] = claripy.BVS(
"blockhash[%s]" % block_num, 256)
state.stack_push(state.env.block_hashes[block_num])
elif op == opcode_values.TIMESTAMP:
state.stack_push(state.env.block_timestamp)
elif op == opcode_values.NUMBER:
state.stack_push(state.env.block_number)
elif op == opcode_values.COINBASE:
state.stack_push(state.env.coinbase)
elif op == opcode_values.DIFFICULTY:
state.stack_push(state.env.difficulty)
elif op == opcode_values.POP:
state.stack_pop()
elif op == opcode_values.JUMP:
addr = solution(state.stack_pop())
if addr >= len(self.code
) or self.code[addr] != opcode_values.JUMPDEST:
raise utils.CodeError("Invalid jump (%i)" % addr)
state.pc = addr
self.add_branch(state)
return False
elif op == opcode_values.JUMPI:
addr, condition = solution(
state.stack_pop()), state.stack_pop()
state_false = state.copy()
if isinstance(condition, claripy.ast.Bool):
state.solver.add(condition)
state_false.solver.add(claripy.Not(condition))
else:
state.solver.add(condition != 0)
state_false.solver.add(condition == 0)
state_false.pc += 1
self.add_branch(state_false)
state.pc = addr
if (state.pc >= len(self.code)
or self.code[state.pc] != opcode_values.JUMPDEST):
raise utils.CodeError("Invalid jump (%i)" % (state.pc - 1))
self.add_branch(state)
return False
elif opcode_values.PUSH1 <= op <= opcode_values.PUSH32:
pushnum = op - opcode_values.PUSH1 + 1
raw_value = self.code.read(pushnum)
state.pc += pushnum
state.stack_push(
bvv(int.from_bytes(raw_value, byteorder="big")))
elif opcode_values.DUP1 <= op <= opcode_values.DUP16:
depth = op - opcode_values.DUP1 + 1
state.stack_push(state.stack[-depth])
elif opcode_values.SWAP1 <= op <= opcode_values.SWAP16:
depth = op - opcode_values.SWAP1 + 1
temp = state.stack[-depth - 1]
state.stack[-depth - 1] = state.stack[-1]
state.stack[-1] = temp
elif opcode_values.LOG0 <= op <= opcode_values.LOG4:
depth = op - opcode_values.LOG0
mstart, msz = (state.stack_pop(), state.stack_pop())
topics = [state.stack_pop() for x in range(depth)]
elif op == opcode_values.SHA3:
start, length = solution(state.stack_pop()), solution(
state.stack_pop())
memory = state.memory.read(start, length)
state.stack_push(Sha3(memory))
elif op == opcode_values.STOP:
return True
elif op == opcode_values.RETURN:
return True
elif op == opcode_values.CALLDATALOAD:
indexes = state.stack_pop()
try:
index = solution(indexes)
except ValueError: # Multiple solutions, let's fuzz.
state.stack_push(indexes) # restore the stack
self.add_for_fuzzing(state, indexes, CALLDATASIZE_FUZZ)
return False
state.solver.add(state.env.calldata_size >= index + 32)
state.stack_push(state.env.calldata.read(index, 32))
elif op == opcode_values.CALLDATASIZE:
state.stack_push(state.env.calldata_size)
elif op == opcode_values.CALLDATACOPY:
old_state = state.copy()
mstart, dstart, size = (
state.stack_pop(),
state.stack_pop(),
state.stack_pop(),
)
mstart, dstart = solution(mstart), solution(dstart)
try:
size = solution(size)
except ValueError:
self.add_for_fuzzing(old_state, size, CALLDATASIZE_FUZZ)
return False
state.memory.copy_from(state.env.calldata, mstart, dstart,
size)
state.solver.add(state.env.calldata_size >= dstart + size)
elif op == opcode_values.CODESIZE:
state.stack_push(bvv(len(self.code)))
elif op == opcode_values.EXTCODESIZE:
addr = state.stack_pop()
if (addr == state.env.address).is_true():
state.stack_push(bvv(len(self.code)))
else:
# TODO: Improve that... It's clearly not constraining enough.
state.stack_push(claripy.BVS("EXTCODESIZE[%s]" % addr,
256))
elif op == opcode_values.CODECOPY:
mem_start, code_start, size = [
solution(state.stack_pop()) for _ in range(3)
]
for i in range(size):
if code_start + i < len(state.env.code):
state.memory.write(
mem_start + i,
1,
claripy.BVV(state.env.code[code_start + i], 8),
)
else:
state.memory.write(mem_start + i, 1, claripy.BVV(0, 8))
elif op == opcode_values.MLOAD:
index = solution(state.stack_pop())
state.stack_push(state.memory.read(index, 32))
elif op == opcode_values.MSTORE:
index, value = solution(state.stack_pop()), not_bool(
state.stack_pop())
state.memory.write(index, 32, value)
elif op == opcode_values.MSTORE8:
index, value = solution(state.stack_pop()), not_bool(
state.stack_pop())
state.memory.write(index, 1, value[7:0])
elif op == opcode_values.MSIZE:
state.stack_push(bvv(state.memory.size()))
elif op == opcode_values.SLOAD:
# TODO: This is inaccurate, because the storage can change
# in a single transaction.
# See commit d98cab834f8f359f01ef805256d179f5529ebe30.
key = state.stack_pop()
if key in state.storage_written:
state.stack_push(state.storage_written[key])
else:
if key not in state.storage_read:
state.storage_read[key] = claripy.BVS(
"storage[%s]" % key, 256)
state.stack_push(state.storage_read[key])
elif op == opcode_values.SSTORE:
# TODO: This is inaccurate, because the storage can change
# in a single transaction.
# See commit d98cab834f8f359f01ef805256d179f5529ebe30.
key = state.stack_pop()
value = state.stack_pop()
state.storage_written[key] = value
elif op == opcode_values.CALL:
state.pc += 1
# First possibility: the call fails
# (always possible with a call stack big enough)
state_fail = state.copy()
state_fail.stack_push(claripy.BoolV(False))
self.add_branch(state_fail)
# Second possibility: success.
state.calls.append(state.stack[-7:])
# pylint:disable=unused-variable
gas, to_, value, meminstart, meminsz, memoutstart, memoutsz = (
state.stack_pop() for _ in range(7))
if solution(memoutsz) != 0:
raise utils.InterpreterError(state,
"CALL seems to return data")
if solution(meminsz) != 0:
raise utils.InterpreterError(state,
"CALL seems to take data")
state.stack_push(claripy.BoolV(True))
self.add_branch(state)
return False
elif op == opcode_values.SELFDESTRUCT:
state.selfdestruct_to = state.stack[-1]
return True
elif op == opcode_values.REVERT:
return False
else:
raise utils.InterpreterError(state, "Unknown opcode %s" % op)
state.pc += 1
def test_sha3_equality_different_length(self):
a = claripy.BVV(1, 8)
s = get_solver()
s.add(Sha3(a) == Sha3(claripy.BVV(1, 256)))
self.assertFalse(s.satisfiable())
def test_sha3_unequality(self):
a = claripy.BVV(1, 256)
s = get_solver()
s.add(Sha3(a) != Sha3(claripy.BVV(1, 256)))
self.assertFalse(s.satisfiable())