def slice_exp(exp, left, right):
size = sub_op(right, left)
logger.debug(f"slicing {exp}, offset {left} bytes, until {right} bytes")
# e.g. mem[32 len 10], 2, 4 == mem[34,2]
if m := match(exp, ("mem", ("range", ":rleft", ":rlen"))):
rleft, rlen = m.rleft, m.rlen
if safe_le_op(add_op(left, size), rlen):
return ("mem", ("range", add_op(rleft, left), size))
else:
return None
def memloc_overwrite(memloc, split):
# returns mem ranges excluding the ones that are *for sure* overwritten by 'split'
# e.g. overwrites(('range', 64, 32), ('range', 70, 10)) -> [('range', 64, 6), (range, 80, 16)]
# e.g. overwrites(('range', 64, 32), ('range', 70, 'unknown')) -> [('range', 64, 32)], bc. 'unknown' can be 0
op, m_left, m_len = memloc
assert op == "range"
op, s_left, s_len = split
assert op == "range"
m_right = add_op(m_left, m_len)
s_right = add_op(s_left, s_len)
if safe_le_op(m_right, s_left) is True: # split after memory - no overlap
return [memloc]
if safe_le_op(s_right, m_left) is True: # split before memory - no overlap
return [memloc]
left_len = sub_op(s_left, m_left)
right_len = sub_op(m_right, s_right)
range_left = ("range", m_left, left_len)
range_right = ("range", s_right, right_len)
left_ge_zero, right_ge_zero = safe_ge_zero(left_len), safe_ge_zero(
right_len)
if left_ge_zero is None or right_ge_zero is None:
# we can't compare some numbers, conservatively return whole range
return [memloc]
res = []
if safe_ge_zero(left_len) is True and left_len != 0:
res.append(range_left)
if safe_ge_zero(right_len) is True and right_len != 0:
res.append(range_right)
return res
def to_mask(num):
num = cleanup_mul_1(num)
if opcode(num) == "not":
return to_neg_mask(num[1])
if opcode(num) == "sub":
if opcode(num[1]) == "exp" and num[2] == 1:
mul = to_exp2(num[1][1])
if mul == None:
return None
mask_pos = 0
mask_len = mul_op(mul, num[1][2])
# add type assert, that num[1][2] < 32?
return (mask_len, sub_op(256, mask_len))
if opcode(num) == "add" and num[1] == -1:
return to_mask((
"sub",
num[2],
1,
))
if type(num) != int:
return None
i = 0
while get_bit(num, i) == 0 and i < 256:
i += 1
mask_pos = i
while get_bit(num, i) == 1 and i < 256:
i += 1
mask_pos_plus_len = i
while i < 256:
if get_bit(num, i) != 0:
return None
i += 1
return mask_pos_plus_len - mask_pos, mask_pos
def apply_mask_to_range(memloc, size, offset):
op, range_pos, range_len = memloc
assert op == "range"
size_bytes, size_bits = to_bytes(size)
offset_bytes, offset_bits = to_bytes(offset)
assert offset_bits == size_bits == 0, (offset_bits, size_bits) # for now
assert safe_le_op(add_op(size_bytes, offset_bytes), range_len) is True, (
size_bytes,
offset_bytes,
range_len,
) # otherwise we need to learn to handle that
range_pos = add_op(range_pos,
sub_op(range_len, add_op(size_bytes, offset_bytes)))
range_len = size_bytes # sub_op(range_len, add_op(offset_bytes, size_bytes))
return ("range", range_pos, range_len)
def _fill_mem(exp, split, split_val):
if exp == ("mem", split):
return split_val
op, memloc = exp
assert op == "mem"
op, m_left, m_len = memloc
assert op == "range"
op, s_left, s_len = split
assert op == "range"
m_right = add_op(m_left, m_len)
s_right = add_op(s_left, s_len)
logger.debug(f"orig memloc: {m_left} len {m_len} right {m_right}")
logger.debug(f"split memloc: {s_left} len {s_len} right {s_right}")
if (
safe_le_op(m_right, s_left) is not False
): # if the split is before memory, or we can't compare - not replacing
logger.debug("split before memory or can't compare - not replacing")
return exp
if safe_le_op(s_right, m_left) is not False: # -,,- after memory
logger.debug("split after memory or can't compare - not replacing")
return exp
left = safe_max_op(s_left, m_left)
right = safe_min_op(s_right, m_right)
logger.debug(f"split begins at {left} ends at {right}")
if left is None or right is None:
return exp # if we can't figure out which one is smaller/larger, we're not replacing
memloc, memloc_max = replace_max_with_MAX(memloc)
split, split_max = replace_max_with_MAX(split)
# 'max' op tends to mess up with all the algebra stuff, so we're replacing
# it with a variable 'MAX' for the time being
if split_max != memloc_max:
logger.warning("different maxes")
return exp
# by now we know:
# - the split overlaps memory for sure
# - we know the boundaries of split
# - so we now return data (before_split, split_val, after_split)
res_left = slice_exp(exp, 0, sub_op(left, m_left))
if res_left is None:
return exp
logger.debug(f"value left untouched on left: {res_left}")
res_right = slice_exp(exp, sub_op(right, m_left), sub_op(m_right, m_left))
if res_right is None:
return exp
logger.debug(f"value right untouched on right: {res_right}")
res = []
if safe_gt_zero(sizeof(res_left)) is True:
logger.debug("size of left untouched > 0, adding to output")
res.append(res_left)
elif safe_gt_zero(sizeof(res_left)) is None:
logger.debug("we don't know if left size > 0, aborting")
return exp
center_in_start = sub_op(left, s_left)
center_in_len = sub_op(right, s_left)
logger.debug(
f"inserted value offset {center_in_start}, length {center_in_len}")
logger.debug(f"cutting this out of {split_val}")
res_center = slice_exp(split_val, center_in_start, center_in_len)
logger.debug(f"inserted value after slicing: {res_center}")
if res_center is None:
return exp
if safe_ge_zero(sizeof(res_center)) is True:
res.append(res_center)
else:
assert False, sizeof(
res_center) # this shouldn't happen considering the above checks?
if safe_ge_zero(sizeof(res_right)) is True:
if sizeof(res_right) != 0:
res.append(res_right)
elif safe_ge_zero(sizeof(res_right)) is None:
return exp
assert None not in res
return ("data", ) + tuple(res)
def splits_mem(memloc, split, memval, split_val=None):
# returns memory values we can be confident of, after overwriting the split part of memory
op, m_left, m_len = memloc
assert op == "range"
op, s_left, s_len = split
assert op == "range"
m_right = add_op(m_left, m_len)
s_right = add_op(s_left, s_len)
logger.debug(f"applying split [{s_left} (len {s_len}) {s_right}]")
logger.debug(f" to [{m_left} (len {m_len}) {m_right}]")
if not safe_ge_zero(s_len):
s_len = "undefined"
s_right = add_op(s_left, s_len)
if safe_le_op(m_right, s_left) is True: # split after memory - no overlap
return [(memloc, memval)]
if safe_le_op(s_right, m_left) is True: # split before memory - no overlap
return [(memloc, memval)]
left = safe_max_op(s_left, m_left)
right = safe_min_op(s_right, m_right)
logger.debug(f"split overwrites memory from {left} to {right}")
# left/right relative to beginning of memory location
in_left = sub_op(left, m_left)
in_right = sub_op(right, m_left)
logger.debug(f"that is, relative to memloc {in_left} to {in_right}")
if safe_le_op(in_left, m_len) is not True or left is None:
logger.debug(
f"we are not sure that m_len: {m_len} is bigger than beginning of split, returning []"
)
return []
assert in_left == 0 if safe_le_op(right, m_left) else True
val_left = slice_exp(memval, 0, in_left) if left is not None else None
val_right = (slice_exp(memval, in_right, sub_op(m_right, m_left))
if right is not None else None)
res = []
left_len = sub_op(left, m_left) # sizeof(val_left)
right_len = sub_op(m_right, right)
if safe_ge_zero(
left_len) is True and left_len != 0 and val_left is not None:
res.append((("range", m_left, left_len), val_left))
if split_val is not None:
center_left = safe_max_op(m_left, s_left)
center_right = safe_min_op(m_right, s_right)
center_len = sub_op(center_right, center_left)
if is_array(opcode(split_val)): # in ARRAY_OPCODES:
# mem[a len b] = calldata[x len b]
# log mem[c len d]
# -> calldata[x+ c - a, center_len]
arr_offset, arr_len = split_val[1:]
center_offset = add_op(arr_offset, sub_op(center_left, s_left))
center_val = (opcode(split_val), center_offset, center_len)
else:
center_offset = sub_op(s_right, center_right)
center_val = mask_op(
split_val,
size=mul_op(center_len, 8),
offset=mul_op(center_offset, 8),
shr=mul_op(center_offset, 8),
)
center_range = ("range", center_left, center_len)
if safe_ge_zero(center_len) and center_len != 0:
res.append((center_range, center_val))
if safe_ge_zero(
right_len) is True and right_len != 0 and val_right is not None:
res.append((("range", right, right_len), val_right))
return res
ret_rows.append((bits(mem_len), 0, row))
continue
if m := match(row, ("storage", ":size", ":off", ":idx")):
ret_rows.append((m.size, 0, row))
continue
if opcode(row) != "mask_shl":
return [(256, 0, value)]
assert opcode(row) == "mask_shl"
_, size, offset, shl, value = row
stor_size = size
stor_offset = add_op(offset, shl)
shl = sub_op(shl, stor_offset)
if type(value) == int:
value = apply_mask(value, size, offset, shl)
elif (m := match(value, ("mem", ":idx"))) and add_op(offset, shl) == 0:
new_memloc = apply_mask_to_range(m.idx, size, offset)
value = ("mem", new_memloc)
else:
value = mask_op(value, size=size, offset=offset, shl=shl)
ret_rows.append((
stor_size,
stor_offset,
value,
))
def eval_bool(exp, known_true=True, symbolic=True):
if exp == known_true:
return True
if is_zero(exp) == known_true:
return False
if exp == is_zero(known_true):
return False
if type(exp) == int:
return exp > 0
if exp in (True, False):
return True
if opcode(exp) == "bool":
return eval_bool(exp[1], known_true=known_true, symbolic=symbolic)
if opcode(exp) == "iszero":
e = eval_bool(exp[1], known_true=known_true, symbolic=symbolic)
if e is not None:
return not e
if opcode(exp) == "or":
res = 0
for e in exp[1:]:
ev = eval_bool(e, known_true=known_true, symbolic=symbolic)
if ev is None:
return None
res = res or ev
return res
#'ge', 'gt', 'eq' - tbd
if opcode(exp) in ["le", "lt"] and opcode(exp) == opcode(known_true):
if exp[1] == known_true[1]:
# ('le', x, sth) while ('le', x, sth2) is known to be true
if eval_bool((opcode(exp), known_true[2], exp[2])) is True:
return True
if not symbolic:
r = eval(exp)
if type(r) == int:
return r != 0
return None
if opcode(exp) == "le":
left = eval(exp[1])
right = eval(exp[2])
if left == right:
return True
if type(left) == int and type(right) == int:
return left <= right
try:
return algebra.le_op(left, right)
except Exception:
return None
if opcode(exp) == "lt":
left = eval(exp[1])
right = eval(exp[2])
if left == right:
return False
if type(left) == int and type(right) == int:
return left < right
try:
return algebra.lt_op(left, right)
except Exception:
return None
if opcode(exp) == "gt":
left = eval(exp[1])
right = eval(exp[2])
if type(left) == int and type(right) == int:
return left > right
if left == right:
return False
try: # a > b iff b < a iff b+1 <= a
le = algebra.lt_op(algebra.add_op(left, 1), right, 1)
logger.debug("le %s %s %s", le, left, right)
if le == True:
return False
if le == False:
return True
if le is None:
return None
except Exception:
pass
if opcode(exp) == "ge":
left = eval(exp[1])
right = eval(exp[2])
if type(left) == int and type(right) == int:
return left >= right
if left == right:
return True
try:
lt = algebra.lt_op(left, right)
if lt == True:
return False
if lt == False:
return True
if lt is None:
return None
except Exception:
pass
if opcode(exp) == "eq":
left = eval(exp[1])
right = eval(exp[2])
if left == right:
return True
if algebra.sub_op(left, right) == 0:
return True
return None
def handle_call(self, op, trace):
stack = self.stack
gas = stack.pop()
addr = stack.pop()
if op == "call":
wei = stack.pop()
else:
assert op == "staticcall"
wei = 0
arg_start = stack.pop()
arg_len = stack.pop()
ret_start = stack.pop()
ret_len = stack.pop()
if addr == 4: # Identity
m = mem_load(arg_start, arg_len)
trace(("setmem", ("range", ret_start, arg_len), m))
stack.append("memcopy.success")
elif type(addr) == int and addr in precompiled:
m = mem_load(arg_start, arg_len)
args = mem_load(arg_start, arg_len)
var_name = precompiled_var_names[addr]
trace(("precompiled", var_name, precompiled[addr], args))
trace(("setmem", ("range", ret_start, ret_len), ("var", var_name)))
stack.append("{}.result".format(precompiled[addr]))
else:
assert op in ("call", "staticcall")
call_trace = (
op,
gas,
addr,
wei,
)
if arg_len == 0:
call_trace += None, None
elif arg_len == 4:
call_trace += mem_load(arg_start, 4), None
else:
fname = mem_load(arg_start, 4)
fparams = mem_load(add_op(arg_start, 4), sub_op(arg_len, 4))
call_trace += fname, fparams
trace(call_trace)
# trace(('comment', mem_load(arg_start, arg_len)))
self.call_len = ret_len
stack.append("ext_call.success")
try:
if lt_op(0, ret_len):
return_data = ("ext_call.return_data", 0, ret_len)
trace(("setmem", ("range", ret_start, ret_len), return_data))
except CannotCompare:
return_data = ("ext_call.return_data", 0, ret_len)
trace(("setmem", ("range", ret_start, ret_len), return_data))
def apply_stack(self, ret, line):
def trace(exp, *format_args):
try:
logger.debug("Trace: %s", str(exp).format(*format_args))
except Exception:
pass
if type(exp) == str:
ret.append(exp.format(*format_args))
else:
ret.append(exp)
stack = self.stack
op = line[1]
previous_len = stack.len()
if "--verbose" in sys.argv or "--explain" in sys.argv:
trace(C.asm(" " + str(stack)))
trace("")
if "push" not in op and "dup" not in op and "swap" not in op:
trace("[{}] {}", line[0], C.asm(op))
else:
if type(line[2]) == str:
trace("[{}] {} {}", line[0], C.asm(op), C.asm(" ”" + line[2] + "”"))
elif line[2] > 0x1000000000:
trace("[{}] {} {}", line[0], C.asm(op), C.asm(hex(line[2])))
else:
trace("[{}] {} {}", line[0], C.asm(op), C.asm(str(line[2])))
param = 0
if len(line) > 2:
param = line[2]
if op in [
"exp",
"and",
"eq",
"div",
"lt",
"gt",
"slt",
"sgt",
"mod",
"xor",
"signextend",
"smod",
"sdiv",
]:
stack.append(arithmetic.eval((op, stack.pop(), stack.pop(),)))
elif op[:4] == "push":
stack.append(param)
elif op == "pop":
stack.pop()
elif op == "dup":
stack.dup(param)
elif op == "mul":
stack.append(mul_op(stack.pop(), stack.pop()))
elif op == "or":
stack.append(or_op(stack.pop(), stack.pop()))
elif op == "add":
stack.append(add_op(stack.pop(), stack.pop()))
elif op == "sub":
left = stack.pop()
right = stack.pop()
if type(left) == int and type(right) == int:
stack.append(arithmetic.sub(left, right))
else:
stack.append(sub_op(left, right))
elif op in ["mulmod", "addmod"]:
stack.append(("mulmod", stack.pop(), stack.pop(), stack.pop()))
elif op == "shl":
off = stack.pop()
exp = stack.pop()
if all_concrete(off, exp):
stack.append(exp << off)
else:
stack.append(mask_op(exp, shl=off))
elif op == "shr":
off = stack.pop()
exp = stack.pop()
if all_concrete(off, exp):
stack.append(exp >> off)
else:
stack.append(mask_op(exp, offset=minus_op(off), shr=off))
elif op == "sar":
off = stack.pop()
exp = stack.pop()
if all_concrete(off, exp):
sign = exp & (1 << 255)
if off >= 256:
if sign:
stack.append(2 ** 256 - 1)
else:
stack.append(0)
else:
shifted = exp >> off
if sign:
shifted |= (2 ** 256 - 1) << (256 - off)
stack.append(shifted)
else:
# FIXME: This won't give the right result...
stack.append(mask_op(exp, offset=minus_op(off), shr=off))
elif op in ["not", "iszero"]:
stack.append((op, stack.pop()))
elif op == "sha3":
p = stack.pop()
n = stack.pop()
res = mem_load(p, n)
self.counter += 1
vname = f"_{self.counter}"
vval = (
"sha3",
res,
)
trace(("setvar", vname, vval))
stack.append(("var", vname))
elif op == "calldataload":
stack.append(("cd", stack.pop(),))
elif op == "byte":
val = stack.pop()
num = stack.pop()
off = sub_op(256, to_bytes(num))
stack.append(mask_op(val, 8, off, shr=off))
elif op == "selfbalance":
stack.append(("balance", "address",))
elif op == "balance":
addr = stack.pop()
if opcode(addr) == "mask_shl" and addr[:4] == ("mask_shl", 160, 0, 0):
stack.append(("balance", addr[4],))
else:
stack.append(("balance", addr,))
elif op == "swap":
stack.swap(param)
elif op[:3] == "log":
p = stack.pop()
s = stack.pop()
topics = []
param = int(op[3])
for i in range(param):
el = stack.pop()
topics.append(el)
trace(("log", mem_load(p, s),) + tuple(topics))
elif op == "sload":
sloc = stack.pop()
stack.append(("storage", 256, 0, sloc))
elif op == "sstore":
sloc = stack.pop()
val = stack.pop()
trace(("store", 256, 0, sloc, val))
elif op == "mload":
memloc = stack.pop()
self.counter += 1
vname = f"_{self.counter}"
trace(("setvar", vname, ("mem", ("range", memloc, 32))))
stack.append(("var", vname))
elif op == "mstore":
memloc = stack.pop()
val = stack.pop()
trace(("setmem", ("range", memloc, 32), val,))
elif op == "mstore8":
memloc = stack.pop()
val = stack.pop()
trace(("setmem", ("range", memloc, 8), val,))
elif op == "extcodecopy":
addr = stack.pop()
mem_pos = stack.pop()
code_pos = stack.pop()
data_len = stack.pop()
trace(
(
"setmem",
("range", mem_pos, data_len),
("extcodecopy", addr, ("range", code_pos, data_len)),
)
)
elif op == "codecopy":
mem_pos = stack.pop()
call_pos = stack.pop()
data_len = stack.pop()
if (type(call_pos), type(data_len)) == (
int,
int,
) and call_pos + data_len < len(self.loader.binary):
res = 0
for i in range(call_pos - 1, call_pos + data_len - 1):
res = res << 8
res += self.loader.binary[
i
] # this breaks with out of range for some contracts
# may be because we're usually getting compiled code binary
# and not runtime binary
trace(
("setmem", ("range", mem_pos, data_len), res)
) # ('bytes', data_len, res)))
else:
trace(
(
"setmem",
("range", mem_pos, data_len),
("code.data", call_pos, data_len,),
)
)
elif op == "codesize":
stack.append(len(self.loader.binary))
elif op == "calldatacopy":
mem_pos = stack.pop()
call_pos = stack.pop()
data_len = stack.pop()
if data_len != 0:
call_data = ("call.data", call_pos, data_len)
# call_data = mask_op(('call.data', bits(add_op(data_len, call_pos))), size=bits(data_len), shl=bits(call_pos))
trace(("setmem", ("range", mem_pos, data_len), call_data))
elif op == "returndatacopy":
mem_pos = stack.pop()
ret_pos = stack.pop()
data_len = stack.pop()
if data_len != 0:
return_data = ("ext_call.return_data", ret_pos, data_len)
# return_data = mask_op(('ext_call.return_data', bits(add_op(data_len, ret_pos))), size=bits(data_len), shl=bits(ret_pos))
trace(("setmem", ("range", mem_pos, data_len), return_data))
elif op == "call":
self.handle_call(op, trace)
elif op == "staticcall":
self.handle_call(op, trace)
elif op == "delegatecall":
gas = stack.pop()
addr = stack.pop()
arg_start = stack.pop()
arg_len = stack.pop()
ret_start = stack.pop()
ret_len = stack.pop()
call_trace = (
"delegatecall",
gas,
addr,
) # arg_start, arg_len, ret_start, ret_len)
if arg_len == 0:
fname = None
fparams = None
elif arg_len == 4:
fname = mem_load(arg_start, 4)
fparams = 0
else:
fname = mem_load(arg_start, 4)
fparams = mem_load(add_op(arg_start, 4), sub_op(arg_len, 4))
call_trace += (fname, fparams)
trace(call_trace)
self.call_len = ret_len
stack.append("delegate.return_code")
if 0 != ret_len:
return_data = ("delegate.return_data", 0, ret_len)
trace(("setmem", ("range", ret_start, ret_len), return_data))
elif op == "callcode":
gas = stack.pop()
addr = stack.pop()
value = stack.pop()
arg_start = stack.pop()
arg_len = stack.pop()
ret_start = stack.pop()
ret_len = stack.pop()
call_trace = (
"callcode",
gas,
addr,
value,
)
if arg_len == 0:
fname = None
fparams = None
elif arg_len == 4:
fname = mem_load(arg_start, 4)
fparams = 0
else:
fname = mem_load(arg_start, 4)
fparams = mem_load(add_op(arg_start, 4), sub_op(arg_len, 4))
call_trace += (fname, fparams)
trace(call_trace)
self.call_len = ret_len
stack.append("callcode.return_code")
if 0 != ret_len:
return_data = ("callcode.return_data", 0, ret_len)
trace(("setmem", ("range", ret_start, ret_len), return_data))
elif op == "create":
wei, mem_start, mem_len = stack.pop(), stack.pop(), stack.pop()
call_trace = ("create", wei)
code = mem_load(mem_start, mem_len)
call_trace += (code,)
trace(call_trace)
stack.append("create.new_address")
elif op == "create2":
wei, mem_start, mem_len, salt = (
stack.pop(),
stack.pop(),
stack.pop(),
stack.pop(),
)
call_trace = ("create2", wei, ("mem", ("range", mem_start, mem_len)), salt)
trace(call_trace)
stack.append("create2.new_address")
elif op == "pc":
stack.append(line[0])
elif op == "msize":
self.counter += 1
vname = f"_{self.counter}"
trace(("setvar", vname, "msize"))
stack.append(("var", vname))
elif op in ("extcodesize", "extcodehash", "blockhash"):
stack.append((op, stack.pop(),))
elif op in [
"callvalue",
"caller",
"address",
"number",
"gas",
"origin",
"timestamp",
"chainid",
"difficulty",
"gasprice",
"coinbase",
"gaslimit",
"calldatasize",
"returndatasize",
]:
stack.append(op)
else:
# TODO: Maybe raise an error directly?
assert op not in [
"jump",
"jumpi",
"revert",
"return",
"stop",
"jumpdest",
"UNKNOWN",
]
if stack.len() - previous_len != opcode_dict.stack_diffs[op]:
logger.error("line: %s", line)
logger.error("stack: %s", stack)
logger.error(
"expected %s, got %s stack diff",
opcode_dict.stack_diffs[op],
stack.len() - previous_len,
)
assert False, f"opcode {op} not processed correctly"
stack.cleanup()