Fixing security issue with lookup returns not tainting the jinja2 environment

CVE-2017-7481

Lookup returns wrap the result in unsafe, however when used through the
standard templar engine, this does not result in the jinja2 environment being
marked as unsafe as a whole. This means the lookup result looses the unsafe
protection and may become simple unicode strings, which can result in bad
things being re-templated.

This also adds a global lookup param and cfg options for lookups to allow
unsafe returns, so users can force the previous (insecure) behavior.
This commit is contained in:
James Cammarata 2017-05-08 10:37:10 -05:00
parent 6f4f7011f1
commit ed56f51f18
4 changed files with 31 additions and 3 deletions

View file

@ -86,6 +86,20 @@ different locations::
Most users will not need to use this feature. See :doc:`dev_guide/developing_plugins` for more details.
.. _allow_unsafe_lookups:
allow_unsafe_lookups
====================
.. versionadded:: 2.2.3, 2.3.1
When enabled, this option allows lookup plugins (whether used in variables as `{{lookup('foo')}}` or as a loop as `with_foo`) to return data that is **not** marked "unsafe". By default, such data is marked as unsafe to prevent the templating engine from evaluating any jinja2 templating language, as this could represent a security risk.
This option is provided to allow for backwards-compatibility, however users should first consider adding `allow_unsafe=True` to any lookups which may be expected to contain data which may be run through the templating engine later. For example::
{{lookup('pipe', '/path/to/some/command', allow_unsafe=True)}}
.. _allow_world_readable_tmpfiles:
allow_world_readable_tmpfiles

View file

@ -282,7 +282,7 @@
# Controls showing custom stats at the end, off by default
#show_custom_stats = True
# Controlls which files to ignore when using a directory as inventory with
# Controls which files to ignore when using a directory as inventory with
# possibly multiple sources (both static and dynamic)
#inventory_ignore_extensions = ~, .orig, .bak, .ini, .cfg, .retry, .pyc, .pyo
@ -294,6 +294,12 @@
# Setting to True keeps them under the ansible_facts namespace, the default is False
#restrict_facts_namespace: True
# When enabled, this option allows lookups (via variables like {{lookup('foo')}} or when used as
# a loop with `with_foo`) to return data that is not marked "unsafe". This means the data may contain
# jinja2 templating language which will be run through the templating engine.
# ENABLING THIS COULD BE A SECURITY RISK
#allow_unsafe_lookups = False
[privilege_escalation]
#become=True
#become_method=sudo

View file

@ -236,6 +236,7 @@ DEFAULT_INVENTORY_IGNORE = get_config(p, DEFAULTS, 'inventory_ignore_extensions
["~", ".orig", ".bak", ".ini", ".cfg", ".retry", ".pyc", ".pyo"], value_type='list')
DEFAULT_VAR_COMPRESSION_LEVEL = get_config(p, DEFAULTS, 'var_compression_level', 'ANSIBLE_VAR_COMPRESSION_LEVEL', 0, value_type='integer')
DEFAULT_INTERNAL_POLL_INTERVAL = get_config(p, DEFAULTS, 'internal_poll_interval', None, 0.001, value_type='float')
DEFAULT_ALLOW_UNSAFE_LOOKUPS = get_config(p, DEFAULTS, 'allow_unsafe_lookups', None, False, value_type='boolean')
ERROR_ON_MISSING_HANDLER = get_config(p, DEFAULTS, 'error_on_missing_handler', 'ANSIBLE_ERROR_ON_MISSING_HANDLER', True, value_type='boolean')
SHOW_CUSTOM_STATS = get_config(p, DEFAULTS, 'show_custom_stats', 'ANSIBLE_SHOW_CUSTOM_STATS', False, value_type='boolean')
NAMESPACE_FACTS = get_config(p, DEFAULTS, 'restrict_facts_namespace', 'ANSIBLE_RESTRICT_FACTS', False, value_type='boolean')

View file

@ -252,6 +252,9 @@ class Templar:
loader=FileSystemLoader(self._basedir),
)
# the current rendering context under which the templar class is working
self.cur_context = None
self.SINGLE_VAR = re.compile(r"^%s\s*(\w*)\s*%s$" % (self.environment.variable_start_string, self.environment.variable_end_string))
self._clean_regex = re.compile(r'(?:%s|%s|%s|%s)' % (
@ -574,6 +577,7 @@ class Templar:
if instance is not None:
wantlist = kwargs.pop('wantlist', False)
allow_unsafe = kwargs.pop('allow_unsafe', C.DEFAULT_ALLOW_UNSAFE_LOOKUPS)
from ansible.utils.listify import listify_lookup_plugin_terms
loop_terms = listify_lookup_plugin_terms(terms=args, templar=self, loader=self._loader, fail_on_undefined=True, convert_bare=False)
@ -588,7 +592,8 @@ class Templar:
"original message: %s" % (name, type(e), e))
ran = None
if ran:
if ran and not allow_unsafe:
from ansible.vars.unsafe_proxy import UnsafeProxy, wrap_var
if wantlist:
ran = wrap_var(ran)
else:
@ -600,6 +605,8 @@ class Templar:
else:
ran = wrap_var(ran)
if self.cur_context:
self.cur_context.unsafe = True
return ran
else:
raise AnsibleError("lookup plugin (%s) not found" % name)
@ -656,7 +663,7 @@ class Templar:
jvars = AnsibleJ2Vars(self, t.globals)
new_context = t.new_context(jvars, shared=True)
self.cur_context = new_context = t.new_context(jvars, shared=True)
rf = t.root_render_func(new_context)
try: