tests/test_security.py

import pytest

from jinja2 import Environment
from jinja2 import escape
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:
    def bar(self):
        return 23

    @unsafe
    def foo(self):
        return 42

    def __repr__(self):
        return "PrivateStuff"


class PublicStuff:
    def bar(self):
        return 23

    def _foo(self):
        return 42

    def __repr__(self):
        return "PublicStuff"


class TestSandbox:
    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_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 str(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(f"{{{{ {expr} }}}}")
            assert t.render(ctx) == rv
            env.intercepted_binops = frozenset(["+"])
            t = env.from_string(f"{{{{ {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(f"{{{{ {expr} }}}}")
            assert t.render(ctx) == rv
            env.intercepted_unops = frozenset(["-"])
            t = env.from_string(f"{{{{ {expr} }}}}")
            with pytest.raises(TemplateRuntimeError):
                t.render(ctx)


class TestStringFormat:
    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;"

    def test_empty_braces_format(self):
        env = SandboxedEnvironment()
        t1 = env.from_string('{{ ("a{}b{}").format("foo", "42")}}')
        t2 = env.from_string('{{ ("a{}b{}"|safe).format(42, "<foo>") }}')
        assert t1.render() == "afoob42"
        assert t2.render() == "a42b&lt;foo&gt;"


class TestStringFormatMap:
    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;"