-
-
Notifications
You must be signed in to change notification settings - Fork 603
Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
Merge pull request #3 from PyCQA/master
Update
- Loading branch information
Showing
18 changed files
with
633 additions
and
249 deletions.
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Original file line number | Diff line number | Diff line change |
---|---|---|
@@ -0,0 +1,271 @@ | ||
# | ||
# Copyright 2018 Victor Torre | ||
# | ||
# Licensed under the Apache License, Version 2.0 (the "License"); you may | ||
# not use this file except in compliance with the License. You may obtain | ||
# a copy of the License at | ||
# | ||
# http://www.apache.org/licenses/LICENSE-2.0 | ||
# | ||
# Unless required by applicable law or agreed to in writing, software | ||
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT | ||
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the | ||
# License for the specific language governing permissions and limitations | ||
# under the License. | ||
|
||
|
||
import ast | ||
|
||
import bandit | ||
from bandit.core import test_properties as test | ||
|
||
|
||
class DeepAssignation(object): | ||
def __init__(self, var_name, ignore_nodes=None): | ||
self.var_name = var_name | ||
self.ignore_nodes = ignore_nodes | ||
|
||
def is_assigned_in(self, items): | ||
assigned = [] | ||
for ast_inst in items: | ||
new_assigned = self.is_assigned(ast_inst) | ||
if new_assigned: | ||
if isinstance(new_assigned, (list, tuple)): | ||
assigned.extend(new_assigned) | ||
else: | ||
assigned.append(new_assigned) | ||
return assigned | ||
|
||
def is_assigned(self, node): | ||
assigned = False | ||
if self.ignore_nodes: | ||
if isinstance(self.ignore_nodes, (list, tuple, object)): | ||
if isinstance(node, self.ignore_nodes): | ||
return assigned | ||
|
||
if isinstance(node, ast.Expr): | ||
assigned = self.is_assigned(node.value) | ||
elif isinstance(node, ast.FunctionDef): | ||
for name in node.args.args: | ||
if isinstance(name, ast.Name): | ||
if name.id == self.var_name.id: | ||
# If is param the assignations are not affected | ||
return assigned | ||
assigned = self.is_assigned_in(node.body) | ||
elif isinstance(node, ast.With): | ||
if node.optional_vars.id == self.var_name.id: | ||
assigned = node | ||
else: | ||
assigned = self.is_assigned_in(node.body) | ||
elif isinstance(node, ast.TryFinally): | ||
assigned = [] | ||
assigned.extend(self.is_assigned_in(node.body)) | ||
assigned.extend(self.is_assigned_in(node.finalbody)) | ||
elif isinstance(node, ast.TryExcept): | ||
assigned = [] | ||
assigned.extend(self.is_assigned_in(node.body)) | ||
assigned.extend(self.is_assigned_in(node.handlers)) | ||
assigned.extend(self.is_assigned_in(node.orelse)) | ||
elif isinstance(node, ast.ExceptHandler): | ||
assigned = [] | ||
assigned.extend(self.is_assigned_in(node.body)) | ||
elif isinstance(node, (ast.If, ast.For, ast.While)): | ||
assigned = [] | ||
assigned.extend(self.is_assigned_in(node.body)) | ||
assigned.extend(self.is_assigned_in(node.orelse)) | ||
elif isinstance(node, ast.AugAssign): | ||
if isinstance(node.target, ast.Name): | ||
if node.target.id == self.var_name.id: | ||
assigned = node.value | ||
elif isinstance(node, ast.Assign) and node.targets: | ||
target = node.targets[0] | ||
if isinstance(target, ast.Name): | ||
if target.id == self.var_name.id: | ||
assigned = node.value | ||
elif isinstance(target, ast.Tuple): | ||
pos = 0 | ||
for name in target.elts: | ||
if name.id == self.var_name.id: | ||
assigned = node.value.elts[pos] | ||
break | ||
pos += 1 | ||
return assigned | ||
|
||
|
||
def evaluate_var(xss_var, parent, until, ignore_nodes=None): | ||
secure = False | ||
if isinstance(xss_var, ast.Name): | ||
if isinstance(parent, ast.FunctionDef): | ||
for name in parent.args.args: | ||
if name.id == xss_var.id: | ||
return False # Params are not secure | ||
|
||
analyser = DeepAssignation(xss_var, ignore_nodes) | ||
for node in parent.body: | ||
if node.lineno >= until: | ||
break | ||
to = analyser.is_assigned(node) | ||
if to: | ||
if isinstance(to, ast.Str): | ||
secure = True | ||
elif isinstance(to, ast.Name): | ||
secure = evaluate_var(to, parent, | ||
to.lineno, ignore_nodes) | ||
elif isinstance(to, ast.Call): | ||
secure = evaluate_call(to, parent, ignore_nodes) | ||
elif isinstance(to, (list, tuple)): | ||
num_secure = 0 | ||
for some_to in to: | ||
if isinstance(some_to, ast.Str): | ||
num_secure += 1 | ||
elif isinstance(some_to, ast.Name): | ||
if evaluate_var(some_to, parent, | ||
node.lineno, ignore_nodes): | ||
num_secure += 1 | ||
else: | ||
break | ||
else: | ||
break | ||
if num_secure == len(to): | ||
secure = True | ||
else: | ||
secure = False | ||
break | ||
else: | ||
secure = False | ||
break | ||
return secure | ||
|
||
|
||
def evaluate_call(call, parent, ignore_nodes=None): | ||
secure = False | ||
evaluate = False | ||
if isinstance(call, ast.Call) and isinstance(call.func, ast.Attribute): | ||
if isinstance(call.func.value, ast.Str) and call.func.attr == 'format': | ||
evaluate = True | ||
if call.keywords or call.kwargs: | ||
evaluate = False # TODO(??) get support for this | ||
|
||
if evaluate: | ||
args = list(call.args) | ||
if call.starargs and isinstance(call.starargs, (ast.List, ast.Tuple)): | ||
args.extend(call.starargs.elts) | ||
|
||
num_secure = 0 | ||
for arg in args: | ||
if isinstance(arg, ast.Str): | ||
num_secure += 1 | ||
elif isinstance(arg, ast.Name): | ||
if evaluate_var(arg, parent, call.lineno, ignore_nodes): | ||
num_secure += 1 | ||
else: | ||
break | ||
elif isinstance(arg, ast.Call): | ||
if evaluate_call(arg, parent, ignore_nodes): | ||
num_secure += 1 | ||
else: | ||
break | ||
else: | ||
break | ||
secure = num_secure == len(args) | ||
|
||
return secure | ||
|
||
|
||
def transform2call(var): | ||
if isinstance(var, ast.BinOp): | ||
is_mod = isinstance(var.op, ast.Mod) | ||
is_left_str = isinstance(var.left, ast.Str) | ||
if is_mod and is_left_str: | ||
new_call = ast.Call() | ||
new_call.args = [] | ||
new_call.args = [] | ||
new_call.starargs = None | ||
new_call.keywords = None | ||
new_call.kwargs = None | ||
new_call.lineno = var.lineno | ||
new_call.func = ast.Attribute() | ||
new_call.func.value = var.left | ||
new_call.func.attr = 'format' | ||
if isinstance(var.right, ast.Tuple): | ||
new_call.args = var.right.elts | ||
elif isinstance(var.right, ast.Dict): | ||
new_call.kwargs = var.right | ||
else: | ||
new_call.args = [var.right] | ||
return new_call | ||
|
||
|
||
def check_risk(node): | ||
description = "Potential XSS on mark_safe function." | ||
xss_var = node.args[0] | ||
|
||
secure = False | ||
|
||
if isinstance(xss_var, ast.Name): | ||
# Check if the var are secure | ||
parent = node.parent | ||
while not isinstance(parent, (ast.Module, ast.FunctionDef)): | ||
parent = parent.parent | ||
|
||
is_param = False | ||
if isinstance(parent, ast.FunctionDef): | ||
for name in parent.args.args: | ||
if name.id == xss_var.id: | ||
is_param = True | ||
break | ||
|
||
if not is_param: | ||
secure = evaluate_var(xss_var, parent, node.lineno) | ||
elif isinstance(xss_var, ast.Call): | ||
parent = node.parent | ||
while not isinstance(parent, (ast.Module, ast.FunctionDef)): | ||
parent = parent.parent | ||
secure = evaluate_call(xss_var, parent) | ||
elif isinstance(xss_var, ast.BinOp): | ||
is_mod = isinstance(xss_var.op, ast.Mod) | ||
is_left_str = isinstance(xss_var.left, ast.Str) | ||
if is_mod and is_left_str: | ||
parent = node.parent | ||
while not isinstance(parent, (ast.Module, ast.FunctionDef)): | ||
parent = parent.parent | ||
new_call = transform2call(xss_var) | ||
secure = evaluate_call(new_call, parent) | ||
|
||
if not secure: | ||
return bandit.Issue( | ||
severity=bandit.MEDIUM, | ||
confidence=bandit.HIGH, | ||
text=description | ||
) | ||
|
||
|
||
@test.checks('Call') | ||
@test.test_id('B703') | ||
def django_mark_safe(context): | ||
"""**B703: Potential XSS on mark_safe function** | ||
.. seealso:: | ||
- https://docs.djangoproject.com/en/dev/topics/ | ||
security/#cross-site-scripting-xss-protection | ||
- https://docs.djangoproject.com/en/dev/ | ||
ref/utils/#module-django.utils.safestring | ||
- https://docs.djangoproject.com/en/dev/ | ||
ref/utils/#django.utils.html.format_html | ||
.. versionadded:: 1.4.1 | ||
""" | ||
if context.is_module_imported_like('django.utils.safestring'): | ||
affected_functions = [ | ||
'mark_safe', | ||
'SafeText', | ||
'SafeUnicode', | ||
'SafeString', | ||
'SafeBytes' | ||
] | ||
if context.call_function_name in affected_functions: | ||
xss = context.node.args[0] | ||
if not isinstance(xss, ast.Str): | ||
return check_risk(context.node) |
Oops, something went wrong.