def testWP(self):
"""
"""
for (expected, stmt, post, typeEnv) in self.testWPCases:
stmtAst = parseStmt(stmt)
got = wp_stmt(stmtAst, post, typeEnv)
assert z3.eq(
got, expected
), "Expected wp {} got {} from pred {} over stmt {}".format(
expected, got, post, stmt)
def insert(e):
found = False
for t in eq_terms:
if z3.eq(t, e):
found = True
break
if not found:
eq_terms.append(e)
return True
return False
def testSP(self):
"""
"""
for (pre, stmt, expected, typeEnv) in self.testSPCases:
stmtAst = parseStmt(stmt)
got = sp_stmt(stmtAst, pre, typeEnv)
assert z3.eq(
got, expected
), "Expected sp {} got {} from pred {} over stmt {}".format(
expected, got, pre, stmt)
def get_function_from_constraints(contract, constraints):
# Todo first we could search for constraints that could be a restriction to the function hash
# Todo a calldata length > 4 constraint could be searched for to
for function in contract.functions:
function_constraint = Extract(
255, 224, BitVec("calldata_" + contract.name + "[0]",
256)) == int(function.hash, 16)
for constraint in constraints:
if eq(constraint, function_constraint):
return function
return None
def testZ3Distinctness():
'''
This test is simply a playground to explore
how z3 handles distinctness and equality checking.
'''
s = Solver()
x, y = Consts('x y', language.PointSort)
s.add(Distinct(x))
s.add(Distinct(y))
print s
# print s.add(Not(eq(x,y)))
# print eq(simplify(x),simplify(y))
# s.add(eq(x,y))
s.add(Not(eq(x,y)))
print s.check()
print s
def equivalent(self, shape: "Shape") -> bool:
"""Returns true iff the given shape is equivalent to this shape."""
if len(self.offsets_with_payloads) != len(shape.offsets_with_payloads):
return False
for (v1, p1), (v2, p2) in zip(
self.offsets_with_payloads, # type: ignore[arg-type]
shape.offsets_with_payloads # type: ignore[arg-type]
):
if v1 != v2:
return False
if isinstance(p1, ExprRef) and isinstance(p2, ExprRef):
if not eq(p1, p2):
return False
elif p1 != p2:
return False
return True
def grow(self):
self.mss = []
self.mcs = []
self.nmcs = []
self.mcs_explain = {}
self.unknown = self.soft_vars
self.update_unknown()
cores = []
while len(self.unknown) > 0:
x = self.unknown.pop()
is_sat = self.s.check(self.mss + [x] + self.nmcs)
if is_sat == z3.sat:
self.mss.append(x)
self.update_unknown()
elif is_sat == z3.unsat:
core = self.s.unsat_core()
core = self.resolve_core(core)
self.mcs_explain[z3.Not(x)] = {
y
for y in core if not z3.eq(x, y)
}
self.mcs.append(x)
self.nmcs.append(z3.Not(x))
cores += [core]
else:
print("solver returned %s" % is_sat)
exit()
mss = [x for x in self.orig_soft_vars if z3.is_true(self.model[x])]
mcs = [x for x in self.orig_soft_vars if not z3.is_true(self.model[x])]
self.s.add(z3.Or(mcs))
core_literals = set([])
cores.sort(key=lambda element: len(element))
for core in cores:
if len(core & core_literals) == 0:
self.relax_core(core)
core_literals |= core
return mss
def outline_loop (name, decls, rules, self_loops, preds, succs):
assert name in self_loops
loop_rules = self_loops [name]
decl = decls [name]
arg_indices = find_arg_indices (decl, loop_rules)
print 'Indices for procedure args:', arg_indices
arg_sorts = [decl.domain (i) for i in arg_indices]
# make new procedure
proc_sorts = arg_sorts + arg_sorts + [decl.range ()]
proc_name = decl.name () + '_proc'
proc_decl = z3.Function (proc_name, *proc_sorts)
# update decls
decls [proc_name] = proc_decl
del decls [name]
# factor the self-loop out into a procedure;
# can have multiple self-loop rules because of the transformation
# Self loop: P(x) /\ t(x,x') -> P(x')
# Transformed rule: t(x,x') /\ P_proc(x',x!next) -> P_proc(x,x!next)
for rule in loop_rules:
curr_args = [rule.get_body_inst ().arg (i) for i in arg_indices]
next_args = [z3.Const (arg.decl ().name () + '!next', arg.sort ()) \
for arg in curr_args]
temp_args = [rule.get_head ().arg (i) for i in arg_indices]
rule_exp = z3.ForAll (rule.qvars + next_args,
z3.Implies (z3.And (proc_decl (*(temp_args + next_args)),
rule.get_trans ()),
proc_decl (*(curr_args + next_args))))
print 'Removing loop rule', repr (rule)
rules.remove (rule)
rules.append (Rule (rule_exp))
# Exit rule: P(x) /\ t(x,y) -> Q(y)
# Exit rule of P_proc: t(x,y) -> P_proc (x,x)
for rule in succs [name]:
curr_args = [rule.get_body_inst ().arg (i) for i in arg_indices]
next_args = curr_args
rule_exp = z3.ForAll (rule.qvars,
z3.Implies (rule.get_trans (),
proc_decl (*(curr_args + next_args))))
rules.append (Rule (rule_exp))
# wire incoming and outgoing rules, via P, together
# in-rule: Q(y) /\ t(y,x) -> P(x)
# out-rule: P(x) /\ t(x,z) -> R(z)
# new rule: Q(y) /\ t(y,x) /\ P_proc (x,x') /\ t(x',z) -> R(z)
for in_rule in preds [name]:
#print 'In rule:', repr (in_rule)
if in_rule.has_body_pred ():
from_inst = in_rule.get_body_inst ()
else:
from_inst = z3.BoolVal (True)
in_trans = in_rule.get_trans ()
curr_args = [in_rule.get_head ().arg (i) for i in arg_indices]
for out_rule in succs [name]:
#print 'Out rule:', repr (out_rule)
# version all out_rule.qvars; treat body args and the rest separately
sub = list ()
out_vars = list ()
# body args
for i in range (decl.arity ()):
v = out_rule.get_body_inst ().arg (i)
if i in arg_indices:
# create new variable
v_new = z3.Const (v.decl ().name () + '_temp', v.sort ())
out_vars.append (v_new)
else:
# use corresponding arg from in_rule; it is unchanged by the loop
v_new = in_rule.get_head ().arg (i)
sub.append ( (v,v_new) )
# rest
for v in out_rule.qvars:
is_body_arg = False
for i in range (decl.arity ()):
if z3.eq (v, out_rule.get_body_inst ().arg (i)):
is_body_arg = True
break
if is_body_arg: continue
v_temp = z3.Const (v.decl ().name () + '_temp', v.sort ())
sub.append ( (v,v_temp) )
out_vars.append (v_temp)
next_args = [z3.substitute (out_rule.get_body_inst ().arg (i), *sub)\
for i in arg_indices]
out_trans = z3.substitute (out_rule.get_trans (), *sub)
to_inst = z3.substitute (out_rule.get_head (), *sub)
# make new rule via proc_decl
rule_exp = z3.ForAll (in_rule.qvars + out_vars,
z3.Implies (z3.And (from_inst,
in_trans,
proc_decl (*(curr_args + next_args)),
out_trans),
to_inst))
rule = Rule (rule_exp)
if rule.is_self_loop ():
insert_in_dict (self_loops, rule.get_head_pred_name (), rule)
else:
insert_in_dict (preds, rule.get_head_pred_name (), rule)
if rule.has_body_pred ():
insert_in_dict (succs, rule.get_body_pred_name (), rule)
rules.append (rule)
# remove incoming and outgoing rules, via P
for in_rule in preds [name]:
print 'Removing in rule', repr (in_rule)
rules.remove (in_rule)
if in_rule.has_body_pred ():
remove_from_dict (succs, in_rule.get_body_pred_name (), in_rule)
del preds [name]
for out_rule in succs [name]:
print 'Removing out rule', repr (out_rule)
rules.remove (out_rule)
remove_from_dict (preds, out_rule.get_head_pred_name (), out_rule)
del succs [name]
def is_data_const(const):
assert (z3.is_const(const))
return z3.eq(const.sort(), data_sort)
def _update_all_ref_tracker(self, instruction: Instruction):
# update all the references
for ref in self.call_result_references + self.timestamp_references + self.reentrancy_references:
ref.update(instruction, self._stack,
self.immutable_storage_references)
# check if there are new references
if instruction.opcode in [
'CALL', "STATICCALL", "DELEGATECALL", "CALLCODE"
]:
h = len(self._stack) - instruction.input_amount
if len(self.reentrancy_references) == 0:
# 如果之前没有任何Storage被读取，也就是为创建任何ReentrancyTracker，那么当前的这个Call就是有reentrancy bug的
tmp = ReentrancyTracker(instruction.addr, h, -1)
tmp.buggy = True
self.reentrancy_references.append(tmp)
# 判断Call的目的地址是否是可变的（mutable）
for ref in self.immutable_storage_references:
if ref.contains(len(self._stack) - 2):
break
else:
# 当前的目的地址包含在某一个mutable storage reference中
# 只有当目的地址不是一个确定值，也就是说不可靠的时候
# new call result reference is generated
call_ref = CallResultTracker(instruction.addr, h)
self.call_result_references.append(call_ref)
elif instruction.opcode == "TIMESTAMP":
# new timestamp reference is generated here
ref = TimestampDepTracker(instruction.addr, len(self._stack))
self.timestamp_references.append(ref)
elif instruction.opcode == "SLOAD":
storage_addr = self._stack[-1]
h = len(self._stack) - instruction.input_amount
# 检查是否需要新建MutableStorageTracker
if not utils.in_list(self.mutable_storage_addresses, storage_addr):
# 是不可变的（immutable)
for ref in self.immutable_storage_references:
if utils.eq(ref.storage_addr, storage_addr):
ref.new(h)
ref.new_born = True
break
else:
ref = ImmutableStorageTracker(instruction.addr, h,
storage_addr,
self._storage[storage_addr])
self.immutable_storage_references.append(ref)
# 检查是否需要新建ReentrancyTracker
for r in self.reentrancy_references:
# check if there already exists the same reference
try:
if utils.is_symbol(storage_addr) and utils.is_symbol(
r.storage_addr) and eq(
simplify(r.storage_addr),
simplify(storage_addr)) or not utils.is_symbol(
storage_addr) and not utils.is_symbol(
r.storage_addr
) and r.storage_addr == storage_addr:
r.new(h)
break
except Exception as e:
print(e)
else:
ref = ReentrancyTracker(instruction.addr, h, storage_addr)
self.reentrancy_references.append(ref)
# 更新mutable storage reference
for ref in self.immutable_storage_references:
if ref.new_born:
ref.new_born = False
else:
ref.update(instruction, self._stack, None)
def exe_with_path_condition(self,
instruction: Instruction,
path_condition: list = []) -> PcPointer:
self._update_all_ref_tracker(instruction)
if instruction.opcode == "SSTORE":
# save the value of every referred storage variable before SSTORE
bak = {}
for ref in self.reentrancy_references:
bak[ref] = self._storage[ref.storage_addr]
if instruction.opcode == "SSTORE" and self.pre_process:
op0 = self._stack[-1]
# 在可信条件下进行修改的Storage变量仍然是可信的（immutable）
caller = z3.Int("Is")
solver = z3.Solver()
solver.add(path_condition)
if "sat" == str(solver.check()):
for storage_addr, storage_value in self._storage.get_storage(
).items():
if not utils.in_list(self.mutable_storage_addresses,
storage_addr):
# solver.add(caller & 0xffffffffffffffffffff != storage_value & 0xffffffffffffffffffff)
mask = 0x000000000000000000000000ffffffffffffffffffffffffffffffffffffffff
if utils.is_symbol(storage_value):
# solver.add(z3.Int(str("Is") + "&" + str(mask)) != z3.Int(str(storage_value) + "&" + str(mask)))
# solver.add(z3.Int(str(mask) + "&" + str("Is")) != z3.Int(str(storage_value) + "&" + str(mask)))
# solver.add(z3.Int(str("Is") + "&" + str(mask)) != z3.Int(str(mask) + "&" + str(storage_value)))
# solver.add(z3.Int(str(mask) + "&" + str("Is")) != z3.Int(str(mask) + "&" + str(storage_value)))
# solver.add(z3.Int(str("Is")) != z3.Int(str(storage_value)))
solver.add(
z3.Int(str("Is")) != z3.Int(str(storage_value))
)
else:
# solver.add(z3.Int(str("Is") + "&" + str(mask)) != storage_value & mask)
# solver.add(z3.Int(str(mask) + "&" + str("Is")) != storage_value & mask)
solver.add(
z3.Int(str("Is")) != storage_value & mask)
if "sat" == str(solver.check()):
# caller不为任意一个可信storage变量的时候仍然可能进行SSTORE,则说明被修改的storage变量是不可靠的
if not utils.in_list(self.mutable_storage_addresses, op0):
self.mutable_storage_addresses.append(op0)
pc_pointer = super().exe(instruction)
if instruction.opcode == "SSTORE":
# check if any referred storage variable is changed after SSTORE
# if len(bak) != len(self._storage):
# # 如果新增了Storage变量，那么一定是做修改了
# ref.storage_changed = True
# if ref.after_used_in_condition:
# ref.changed_after_condition = True
# if not ref.after_call:
# ref.changed_before_call = True
# else:
# 如果Storage变量的个数没变，那么就检查每一个变量的值有没有改变
for ref, value in bak.items():
if utils.is_symbol(value) is not utils.is_symbol(self._storage[ref.storage_addr]) or \
utils.is_symbol(value) and not eq(simplify(value),
simplify(self._storage[ref.storage_addr])) or \
not utils.is_symbol(value) and value != self._storage[ref.storage_addr]:
ref.storage_changed = True
if ref.after_used_in_condition:
ref.changed_after_condition = True
if not ref.after_call:
ref.changed_before_call = True
return pc_pointer
def notEqual(v, vars):
return z3.And([v != i for i in vars if not z3.eq(v,i)])
def is_storage_primitive(storage):
if storage:
for index, content in storage._storage.items():
if isinstance(content, int) or not eq(content, BitVec("storage[" + str(index) + "]", 256)):
return False
return True
def key_fun(root):
f = lambda pred: z3.eq(pred.root, root)
pred = utils.find_first(f, preds)
# Prepend branching factor to prioritize linear structs in lexicographic sort
return (pred.struct.branching_factor, str(root))
def notEqual(v, vars):
return z3.And([v != i for i in vars if not z3.eq(v, i)])
def substitute(self, other, expr):
def update_term(t, args):
n = len(args)
# Need to pass an AstArray type into Z3_update_term, not a python list
args_ast_arr = (z3.Ast * n)()
for i in range(n):
args_ast_arr[i] = args[i].as_ast()
return _to_expr_ref(
z3.Z3_update_term(t.ctx_ref(), t.as_ast(), n, args_ast_arr),
t.ctx)
cache = z3.AstMap(ctx=expr.ctx)
for addr, state in self._expanded_global_state.items():
other_state = other.initial_contract_state(addr)
cache[state.storage] = other_state.storage
cache[state.balance] = other_state.balance
cache[state.nonce] = other_state.nonce
fnsubs = []
for k, v in self._cache.items():
if isinstance(v, mem.Memory):
# Uses of Memory objects will produce an expression containing
# the underlying array object (_mem). If required the index
# (_idx) will have been substituted with the actual indexing
# expression at that point, so we do not need to consider it
# here.
cache[v._mem] = getattr(other, k)()._mem
elif z3.is_app(v) and v.num_args() > 0:
fnsubs.append((v, getattr(other, k)()))
else:
cache[v] = getattr(other, k)()
todo = [expr]
while todo:
n = todo[-1]
if n in cache:
todo.pop()
elif z3.is_var(n):
cache[n] = n
todo.pop()
elif z3.is_app(n):
new_args = []
for i in range(n.num_args()):
arg = n.arg(i)
if arg not in cache:
todo.append(arg)
else:
new_args.append(cache[arg])
# Only actually do the substitution if all the arguments have
# already been processed
if len(new_args) == n.num_args():
todo.pop()
fn = n.decl()
for oldfn, newfn in fnsubs:
if z3.eq(fn, oldfn):
new_fn = z3.substitute_vars(newfn, *new_args)
break
else:
# TODO only if new_args != old_args
if len(new_args) != fn.arity():
new_fn = update_term(n, new_args)
else:
new_fn = fn(*new_args)
cache[n] = new_fn
else:
assert z3.is_quantifier(n)
# Not currently implemented as don't use quanitifers at the
# moment
raise NotImplementedError()
return cache[expr]