openstack/nova
Code Issues Proposed changes

Additional tests for safe parsing with minidom

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For nova, forbid_dtd is going to be true always, however
if someone picks up this code and tries forbid_dtd = False
then the existing code is not good enough. we need to protect
against external entities/dtd and not allow notations as well.
Added a few more handlers and test cases to cover that use
case.

Change-Id: If50f690e015f2bf837b403edf552e35d7af8c907
This commit is contained in:
Davanum Srinivas
2013-02-20 11:06:21 -05:00
committed by Gerrit Code Review
parent 2e771b1032
commit 14df42b15f
2 changed files with 61 additions and 2 deletions
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45
nova/tests/test_utils.py
View File

@@ -23,6 +23,7 @@ import os
import os.path import os.path
import StringIO import StringIO
import tempfile import tempfile
from xml.dom import minidom
import mox import mox
import netaddr import netaddr
@@ -1059,3 +1060,47 @@ class StringLengthTestCase(test.TestCase):
self.assertRaises(exception.InvalidInput, self.assertRaises(exception.InvalidInput,
utils.check_string_length, utils.check_string_length,
'a' * 256, 'name', max_length=255) 'a' * 256, 'name', max_length=255)
class SafeParserTestCase(test.TestCase):
def test_external_dtd(self):
xml_string = ("""<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html>
<head/>
<body>html with dtd</body>
</html>""")
parser = utils.ProtectedExpatParser(forbid_dtd=False,
forbid_entities=True)
self.assertRaises(ValueError,
minidom.parseString,
xml_string, parser)
def test_external_file(self):
xml_string = """<!DOCTYPE external [
<!ENTITY ee SYSTEM "file:///PATH/TO/root.xml">
]>
<root>&ee;</root>"""
parser = utils.ProtectedExpatParser(forbid_dtd=False,
forbid_entities=True)
self.assertRaises(ValueError,
minidom.parseString,
xml_string, parser)
def test_notation(self):
xml_string = """<?xml version="1.0" standalone="no"?>
<!-- comment data -->
<!DOCTYPE x [
<!NOTATION notation SYSTEM "notation.jpeg">
]>
<root attr1="value1">
</root>"""
parser = utils.ProtectedExpatParser(forbid_dtd=False,
forbid_entities=True)
self.assertRaises(ValueError,
minidom.parseString,
xml_string, parser)

18
nova/utils.py
View File

@@ -672,19 +672,33 @@ class ProtectedExpatParser(expatreader.ExpatParser):
def entity_decl(self, entityName, is_parameter_entity, value, base, def entity_decl(self, entityName, is_parameter_entity, value, base,
systemId, publicId, notationName): systemId, publicId, notationName):
raise ValueError("<!ENTITY> forbidden") raise ValueError("<!ENTITY> entity declaration forbidden")
def unparsed_entity_decl(self, name, base, sysid, pubid, notation_name): def unparsed_entity_decl(self, name, base, sysid, pubid, notation_name):
# expat 1.2 # expat 1.2
raise ValueError("<!ENTITY> forbidden") raise ValueError("<!ENTITY> unparsed entity forbidden")
def external_entity_ref(self, context, base, systemId, publicId):
raise ValueError("<!ENTITY> external entity forbidden")
def notation_decl(self, name, base, sysid, pubid):
raise ValueError("<!ENTITY> notation forbidden")
def reset(self): def reset(self):
expatreader.ExpatParser.reset(self) expatreader.ExpatParser.reset(self)
if self.forbid_dtd: if self.forbid_dtd:
self._parser.StartDoctypeDeclHandler = self.start_doctype_decl self._parser.StartDoctypeDeclHandler = self.start_doctype_decl
self._parser.EndDoctypeDeclHandler = None
if self.forbid_entities: if self.forbid_entities:
self._parser.EntityDeclHandler = self.entity_decl self._parser.EntityDeclHandler = self.entity_decl
self._parser.UnparsedEntityDeclHandler = self.unparsed_entity_decl self._parser.UnparsedEntityDeclHandler = self.unparsed_entity_decl
self._parser.ExternalEntityRefHandler = self.external_entity_ref
self._parser.NotationDeclHandler = self.notation_decl
try:
self._parser.SkippedEntityHandler = None
except AttributeError:
# some pyexpat versions do not support SkippedEntity
pass
def safe_minidom_parse_string(xml_string): def safe_minidom_parse_string(xml_string):