Prevent losing unsafe from lookups (#77609) (#77650)

* Prevent losing unsafe from lookups

This patch fixes a bug which under certain conditions results in data
returned from lookups not being marked as unsafe.

Each time Templar.do_template is invoked a new AnsibleContext is
created and stored effectively at two places:
1) as an instance variable in templar_obj.cur_context
2) as a local variable called new_context in do_template method of Templar

Due to custom functionality in Ansible's Context that allows for nested
templating it is possible that during resolving variable's value
template/do_template method is called recursively again, again creating
a new context. At that point the problem manifests itself because as
mentioned in 1) above the context is overwriten on the templar object
which means that any subsequent calls to _lookup will use the new
context to mark it as unsafe which is now different to the local
new_context which is used for testing for unsafe property.

The solution to the problem appears to be to restore the original
context inside do_template and also to eliminate the local variable
new_context to prevent problems in the future.

It appears that we don't have a better way of storing the context other
than as some form of global variable and so this appears to be the
"best" solution possible at this point. Hopefully data tagging will be
the solution here.

For more examples see unit and integration tests included in this patch.

Fixes #77535

(cherry picked from commit 3980eb8c09d170a861351f8aff4a1aa1a8cbb626)

4 files changed, 81 insertions, 3 deletions

diff --git a/changelogs/fragments/77535-prevent-losing-unsafe-lookups.yml b/changelogs/fragments/77535-prevent-losing-unsafe-lookups.yml
new file mode 100644
index 0000000000..14ae6f2fed
--- /dev/null
+++ b/changelogs/fragments/77535-prevent-losing-unsafe-lookups.yml
@@ -0,0 +1,2 @@
+bugfixes:
+  - Prevent losing unsafe on results returned from lookups (https://github.com/ansible/ansible/issues/77535)
diff --git a/lib/ansible/template/__init__.py b/lib/ansible/template/__init__.py
index e605a7f6e9..c1a48b05c0 100644
--- a/lib/ansible/template/__init__.py
+++ b/lib/ansible/template/__init__.py
@@ -1077,8 +1077,12 @@ class Templar:
 
             jvars = AnsibleJ2Vars(self, t.globals)
 
-            self.cur_context = new_context = t.new_context(jvars, shared=True)
-            rf = t.root_render_func(new_context)
+            # In case this is a recursive call to do_template we need to
+            # save/restore cur_context to prevent overriding __UNSAFE__.
+            cached_context = self.cur_context
+
+            self.cur_context = t.new_context(jvars, shared=True)
+            rf = t.root_render_func(self.cur_context)
 
             try:
                 if not self.jinja2_native and not convert_data:
@@ -1086,7 +1090,7 @@ class Templar:
                 else:
                     res = self.environment.concat(rf)
 
-                unsafe = getattr(new_context, 'unsafe', False)
+                unsafe = getattr(self.cur_context, 'unsafe', False)
                 if unsafe:
                     res = wrap_var(res)
             except TypeError as te:
@@ -1097,6 +1101,8 @@ class Templar:
                 else:
                     display.debug("failing because of a type error, template data is: %s" % to_text(data))
                     raise AnsibleError("Unexpected templating type error occurred on (%s): %s" % (to_native(data), to_native(te)))
+            finally:
+                self.cur_context = cached_context
 
             if isinstance(res, string_types) and preserve_trailing_newlines:
                 # The low level calls above do not preserve the newline
diff --git a/test/integration/targets/template/unsafe.yml b/test/integration/targets/template/unsafe.yml
index 6746e1ea0c..bef9a4b450 100644
--- a/test/integration/targets/template/unsafe.yml
+++ b/test/integration/targets/template/unsafe.yml
@@ -17,3 +17,48 @@
         that:
         - this_always_safe == imunsafe
         - imunsafe == this_was_unsafe.strip()
+
+
+- hosts: localhost
+  gather_facts: false
+  vars:
+    output_dir: "{{ lookup('env', 'OUTPUT_DIR') }}"
+  tasks:
+    - set_fact:
+        unsafe_foo: "{{ lookup('list', var0) }}"
+      vars:
+        var0: "{{ var1 }}"
+        var1:
+          - unsafe
+
+    - assert:
+        that:
+          - "{{ unsafe_foo[0] | type_debug == 'AnsibleUnsafeText' }}"
+
+    - block:
+      - copy:
+          dest: "{{ file_name }}"
+          content: !unsafe "{{ i_should_not_be_templated }}"
+
+      - set_fact:
+          file_content: "{{ lookup('file', file_name) }}"
+
+      - assert:
+          that:
+            - not file_content is contains('unsafe')
+
+      - set_fact:
+          file_content: "{{ lookup('file', file_name_tmpl) }}"
+        vars:
+          file_name_tmpl: "{{ file_name }}"
+
+      - assert:
+          that:
+            - not file_content is contains('unsafe')
+      vars:
+        file_name: "{{ output_dir }}/unsafe_file"
+        i_should_not_be_templated: unsafe
+      always:
+        - file:
+            dest: "{{ file_name }}"
+            state: absent
diff --git a/test/units/template/test_templar.py b/test/units/template/test_templar.py
index 1d35771245..e922f95f36 100644
--- a/test/units/template/test_templar.py
+++ b/test/units/template/test_templar.py
@@ -443,3 +443,28 @@ class TestAnsibleContext(BaseTemplar, unittest.TestCase):
     def test_is_unsafe(self):
         context = self._context()
         self.assertFalse(context._is_unsafe(AnsibleUndefined()))
+
+
+def test_unsafe_lookup():
+    res = Templar(
+        None,
+        variables={
+            'var0': '{{ var1 }}',
+            'var1': ['unsafe'],
+        }
+    ).template('{{ lookup("list", var0) }}')
+    assert getattr(res[0], '__UNSAFE__', False)
+
+
+def test_unsafe_lookup_no_conversion():
+    res = Templar(
+        None,
+        variables={
+            'var0': '{{ var1 }}',
+            'var1': ['unsafe'],
+        }
+    ).template(
+        '{{ lookup("list", var0) }}',
+        convert_data=False,
+    )
+    assert getattr(res, '__UNSAFE__', False)