python-jinja2/CVE-2019-10906-sandbox-str-format_map.patch

From a2a6c930bcca591a25d2b316fcfd2d6793897b26 Mon Sep 17 00:00:00 2001
From: Armin Ronacher <armin.ronacher@active-4.com>
Date: Sat, 6 Apr 2019 10:50:47 -0700
Subject: [PATCH] sandbox str.format_map

reason: fix CVE-2019-10906 python-jinja2:str.format_map allows sandbox
escape.

Reference: https://bugzilla.redhat.com/show_bug.cgi?id=1698839
---
 jinja2/sandbox.py      | 17 ++++++++++++++---
 tests/test_security.py | 19 +++++++++++++++++++
 2 files changed, 33 insertions(+), 3 deletions(-)

diff --git a/Jinja2-2.10/jinja2/sandbox.py b/Jinja2-2.10/jinja2/sandbox.py
index 93fb9d4..752e812 100644
--- a/Jinja2-2.10/jinja2/sandbox.py
+++ b/Jinja2-2.10/jinja2/sandbox.py
@@ -137,7 +137,7 @@ class _MagicFormatMapping(Mapping):
 def inspect_format_method(callable):
     if not isinstance(callable, (types.MethodType,
                                  types.BuiltinMethodType)) or \
-       callable.__name__ != 'format':
+       callable.__name__ not in ('format', 'format_map'):
         return None
     obj = callable.__self__
     if isinstance(obj, string_types):
@@ -402,7 +402,7 @@ class SandboxedEnvironment(Environment):
             obj.__class__.__name__
         ), name=attribute, obj=obj, exc=SecurityError)
 
-    def format_string(self, s, args, kwargs):
+    def format_string(self, s, args, kwargs, format_func=None):
         """If a format call is detected, then this is routed through this
         method so that our safety sandbox can be used for it.
         """
@@ -410,6 +410,17 @@ class SandboxedEnvironment(Environment):
             formatter = SandboxedEscapeFormatter(self, s.escape)
         else:
             formatter = SandboxedFormatter(self)
+
+        if format_func is not None and format_func.__name__ == 'format_map':
+            if len(args) != 1 or kwargs:
+                raise TypeError(
+                    'format_map() takes exactly one argument %d given'
+                    % (len(args) + (kwargs is not None))
+                )
+
+            kwargs = args[0]
+            args = None
+
         kwargs = _MagicFormatMapping(args, kwargs)
         rv = formatter.vformat(s, args, kwargs)
         return type(s)(rv)
@@ -418,7 +429,7 @@ class SandboxedEnvironment(Environment):
         """Call an object from sandboxed code."""
         fmt = inspect_format_method(__obj)
         if fmt is not None:
-            return __self.format_string(fmt, args, kwargs)
+            return __self.format_string(fmt, args, kwargs, __obj)
 
         # the double prefixes are to avoid double keyword argument
         # errors when proxying the call.
diff --git a/Jinja2-2.10/tests/test_security.py b/Jinja2-2.10/tests/test_security.py
index 8e4222e..5c8639c 100644
--- a/Jinja2-2.10/tests/test_security.py
+++ b/Jinja2-2.10/tests/test_security.py
@@ -187,3 +187,22 @@ class TestStringFormat(object):
         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;'
-- 
1.8.3.1