tests/test_security.py

# -*- coding: utf-8 -*-
"""
    jinja2.testsuite.security
    ~~~~~~~~~~~~~~~~~~~~~~~~~

    Checks the sandbox and other security features.

    :copyright: (c) 2017 by the Jinja Team.
    :license: BSD, see LICENSE for more details.
"""
import pytest

from jinja2 import Environment
from jinja2 import escape
from jinja2 import Markup
from jinja2._compat import text_type
from jinja2.exceptions import SecurityError
from jinja2.exceptions import TemplateRuntimeError
from jinja2.exceptions import TemplateSyntaxError
from jinja2.nodes import EvalContext
from jinja2.sandbox import ImmutableSandboxedEnvironment
from jinja2.sandbox import SandboxedEnvironment
from jinja2.sandbox import unsafe


class PrivateStuff(object):

    def bar(self):
        return 23

    @unsafe
    def foo(self):
        return 42

    def __repr__(self):
        return 'PrivateStuff'


class PublicStuff(object):
    bar = lambda self: 23
    _foo = lambda self: 42

    def __repr__(self):
        return 'PublicStuff'


@pytest.mark.sandbox
class TestSandbox(object):

    def test_unsafe(self, env):
        env = SandboxedEnvironment()
        pytest.raises(SecurityError, env.from_string("{{ foo.foo() }}").render,
                      foo=PrivateStuff())
        assert env.from_string("{{ foo.bar() }}").render(foo=PrivateStuff()) == '23'

        pytest.raises(SecurityError,
                      env.from_string("{{ foo._foo() }}").render,
                      foo=PublicStuff())
        assert env.from_string("{{ foo.bar() }}").render(foo=PublicStuff()) == '23'
        assert env.from_string("{{ foo.__class__ }}").render(foo=42) == ''
        assert env.from_string("{{ foo.func_code }}").render(foo=lambda:None) == ''
        # security error comes from __class__ already.
        pytest.raises(SecurityError, env.from_string(
            "{{ foo.__class__.__subclasses__() }}").render, foo=42)

    def test_immutable_environment(self, env):
        env = ImmutableSandboxedEnvironment()
        pytest.raises(SecurityError, env.from_string(
            '{{ [].append(23) }}').render)
        pytest.raises(SecurityError, env.from_string(
            '{{ {1:2}.clear() }}').render)

    def test_restricted(self, env):
        env = SandboxedEnvironment()
        pytest.raises(TemplateSyntaxError, env.from_string,
                      "{% for item.attribute in seq %}...{% endfor %}")
        pytest.raises(TemplateSyntaxError, env.from_string,
                      "{% for foo, bar.baz in seq %}...{% endfor %}")

    def test_markup_operations(self, env):
        # adding two strings should escape the unsafe one
        unsafe = '<script type="application/x-some-script">alert("foo");</script>'
        safe = Markup('<em>username</em>')
        assert unsafe + safe == text_type(escape(unsafe)) + text_type(safe)

        # string interpolations are safe to use too
        assert Markup('<em>%s</em>') % '<bad user>' == \
            '<em>&lt;bad user&gt;</em>'
        assert Markup('<em>%(username)s</em>') % {
            'username': '<bad user>'
        } == '<em>&lt;bad user&gt;</em>'

        # an escaped object is markup too
        assert type(Markup('foo') + 'bar') is Markup

        # and it implements __html__ by returning itself
        x = Markup("foo")
        assert x.__html__() is x

        # it also knows how to treat __html__ objects
        class Foo(object):
            def __html__(self):
                return '<em>awesome</em>'

            def __unicode__(self):
                return 'awesome'
        assert Markup(Foo()) == '<em>awesome</em>'
        assert Markup('<strong>%s</strong>') % Foo() == \
            '<strong><em>awesome</em></strong>'

        # escaping and unescaping
        assert escape('"<>&\'') == '&#34;&lt;&gt;&amp;&#39;'
        assert Markup("<em>Foo &amp; Bar</em>").striptags() == "Foo & Bar"
        assert Markup("&lt;test&gt;").unescape() == "<test>"

    def test_template_data(self, env):
        env = Environment(autoescape=True)
        t = env.from_string('{% macro say_hello(name) %}'
                            '<p>Hello {{ name }}!</p>{% endmacro %}'
                            '{{ say_hello("<blink>foo</blink>") }}')
        escaped_out = '<p>Hello &lt;blink&gt;foo&lt;/blink&gt;!</p>'
        assert t.render() == escaped_out
        assert text_type(t.module) == escaped_out
        assert escape(t.module) == escaped_out
        assert t.module.say_hello('<blink>foo</blink>') == escaped_out
        assert escape(t.module.say_hello(
            EvalContext(env), '<blink>foo</blink>')) == escaped_out
        assert escape(t.module.say_hello(
            '<blink>foo</blink>')) == escaped_out

    def test_attr_filter(self, env):
        env = SandboxedEnvironment()
        tmpl = env.from_string('{{ cls|attr("__subclasses__")() }}')
        pytest.raises(SecurityError, tmpl.render, cls=int)

    def test_binary_operator_intercepting(self, env):
        def disable_op(left, right):
            raise TemplateRuntimeError('that operator so does not work')
        for expr, ctx, rv in ('1 + 2', {}, '3'), ('a + 2', {'a': 2}, '4'):
            env = SandboxedEnvironment()
            env.binop_table['+'] = disable_op
            t = env.from_string('{{ %s }}' % expr)
            assert t.render(ctx) == rv
            env.intercepted_binops = frozenset(['+'])
            t = env.from_string('{{ %s }}' % expr)
            with pytest.raises(TemplateRuntimeError):
                t.render(ctx)

    def test_unary_operator_intercepting(self, env):
        def disable_op(arg):
            raise TemplateRuntimeError('that operator so does not work')
        for expr, ctx, rv in ('-1', {}, '-1'), ('-a', {'a': 2}, '-2'):
            env = SandboxedEnvironment()
            env.unop_table['-'] = disable_op
            t = env.from_string('{{ %s }}' % expr)
            assert t.render(ctx) == rv
            env.intercepted_unops = frozenset(['-'])
            t = env.from_string('{{ %s }}' % expr)
            with pytest.raises(TemplateRuntimeError):
                t.render(ctx)


@pytest.mark.sandbox
class TestStringFormat(object):

    def test_basic_format_safety(self):
        env = SandboxedEnvironment()
        t = env.from_string('{{ "a{0.__class__}b".format(42) }}')
        assert t.render() == 'ab'

    def test_basic_format_all_okay(self):
        env = SandboxedEnvironment()
        t = env.from_string('{{ "a{0.foo}b".format({"foo": 42}) }}')
        assert t.render() == 'a42b'

    def test_safe_format_safety(self):
        env = SandboxedEnvironment()
        t = env.from_string('{{ ("a{0.__class__}b{1}"|safe).format(42, "<foo>") }}')
        assert t.render() == 'ab&lt;foo&gt;'

    def test_safe_format_all_okay(self):
        env = SandboxedEnvironment()
        t = env.from_string('{{ ("a{0.foo}b{1}"|safe).format({"foo": 42}, "<foo>") }}')
        assert t.render() == 'a42b&lt;foo&gt;'


@pytest.mark.sandbox
@pytest.mark.skipif(not hasattr(str, 'format_map'), reason='requires str.format_map method')
class TestStringFormatMap(object):
    def test_basic_format_safety(self):
        env = SandboxedEnvironment()
        t = env.from_string('{{ "a{x.__class__}b".format_map({"x":42}) }}')
        assert t.render() == 'ab'

    def test_basic_format_all_okay(self):
        env = SandboxedEnvironment()
        t = env.from_string('{{ "a{x.foo}b".format_map({"x":{"foo": 42}}) }}')
        assert t.render() == 'a42b'

    def test_safe_format_all_okay(self):
        env = SandboxedEnvironment()
        t = env.from_string('{{ ("a{x.foo}b{y}"|safe).format_map({"x":{"foo": 42}, "y":"<foo>"}) }}')
        assert t.render() == 'a42b&lt;foo&gt;'