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commit 30042d475bf084c6723c6217a21598d9247a9c41
Author: Tim Graham <timograham@gmail.com>
Date: Fri Aug 8 10:20:08 2014 -0400
[1.4.x] Fixed #23157 -- Removed O(n) algorithm when uploading duplicate file names.
This is a security fix. Disclosure following shortly.
Debian note: This patch also includes the minimum backport of additional
functionality to django.utils.six to support this patch, but does not change
any functionality therein.
--- a/django/core/files/storage.py
+++ b/django/core/files/storage.py
@@ -1,12 +1,12 @@
import os
import errno
import urlparse
-import itertools
from django.conf import settings
from django.core.exceptions import ImproperlyConfigured, SuspiciousOperation
from django.core.files import locks, File
from django.core.files.move import file_move_safe
+from django.utils.crypto import get_random_string
from django.utils.encoding import force_unicode
from django.utils.functional import LazyObject
from django.utils.importlib import import_module
@@ -66,13 +66,12 @@ class Storage(object):
"""
dir_name, file_name = os.path.split(name)
file_root, file_ext = os.path.splitext(file_name)
- # If the filename already exists, add an underscore and a number (before
- # the file extension, if one exists) to the filename until the generated
- # filename doesn't exist.
- count = itertools.count(1)
+ # If the filename already exists, add an underscore and a random 7
+ # character alphanumeric string (before the file extension, if one
+ # exists) to the filename until the generated filename doesn't exist.
while self.exists(name):
# file_ext includes the dot.
- name = os.path.join(dir_name, "%s_%s%s" % (file_root, count.next(), file_ext))
+ name = os.path.join(dir_name, "%s_%s%s" % (file_root, get_random_string(7), file_ext))
return name
--- a/docs/howto/custom-file-storage.txt
+++ b/docs/howto/custom-file-storage.txt
@@ -86,5 +86,13 @@ the provided filename into account. The
will have already cleaned to a filename valid for the storage system, according
to the ``get_valid_name()`` method described above.
-The code provided on ``Storage`` simply appends ``"_1"``, ``"_2"``, etc. to the
-filename until it finds one that's available in the destination directory.
+.. versionchanged:: 1.4.14
+
+ If a file with ``name`` already exists, an underscore plus a random 7
+ character alphanumeric string is appended to the filename before the
+ extension.
+
+ Previously, an underscore followed by a number (e.g. ``"_1"``, ``"_2"``,
+ etc.) was appended to the filename until an avaible name in the destination
+ directory was found. A malicious user could exploit this deterministic
+ algorithm to create a denial-of-service attack.
--- a/tests/regressiontests/file_storage/tests.py
+++ b/tests/regressiontests/file_storage/tests.py
@@ -1,5 +1,6 @@
# -*- coding: utf-8 -*-
import os
+import re
import shutil
import sys
import tempfile
@@ -31,15 +32,15 @@ except ImportError:
class FileStorageTests(unittest.TestCase):
storage_class = FileSystemStorage
-
+
def setUp(self):
self.temp_dir = tempfile.mktemp()
os.makedirs(self.temp_dir)
self.storage = self.storage_class(location=self.temp_dir)
-
+
def tearDown(self):
os.rmdir(self.temp_dir)
-
+
def test_file_access_options(self):
"""
Standard file access options are available, and work as expected.
@@ -53,7 +54,7 @@ class FileStorageTests(unittest.TestCase
f = self.storage.open('storage_test', 'r')
self.assertEqual(f.read(), 'storage contents')
f.close()
-
+
self.storage.delete('storage_test')
self.failIf(self.storage.exists('storage_test'))
@@ -81,7 +82,7 @@ class CustomStorage(FileSystemStorage):
class CustomStorageTests(FileStorageTests):
storage_class = CustomStorage
-
+
def test_custom_get_available_name(self):
first = self.storage.save('custom_storage', ContentFile('custom contents'))
self.assertEqual(first, 'custom_storage')
@@ -109,6 +110,9 @@ class SlowFile(ContentFile):
time.sleep(1)
return super(ContentFile, self).chunks()
+FILE_SUFFIX_REGEX = '[A-Za-z0-9]{7}'
+
+
class FileSaveRaceConditionTest(TestCase):
def setUp(self):
self.storage_dir = tempfile.mkdtemp()
@@ -125,10 +129,9 @@ class FileSaveRaceConditionTest(TestCase
self.thread.start()
name = self.save_file('conflict')
self.thread.join()
- self.assert_(self.storage.exists('conflict'))
- self.assert_(self.storage.exists('conflict_1'))
- self.storage.delete('conflict')
- self.storage.delete('conflict_1')
+ files = sorted(os.listdir(self.storage_dir))
+ self.assertEqual(files[0], 'conflict')
+ self.assertTrue(re.match('conflict_%s' % FILE_SUFFIX_REGEX, files[1]))
class FileStoragePermissions(TestCase):
def setUp(self):
@@ -165,9 +168,11 @@ class FileStoragePathParsing(TestCase):
self.storage.save('dotted.path/test', ContentFile("1"))
self.storage.save('dotted.path/test', ContentFile("2"))
- self.failIf(os.path.exists(os.path.join(self.storage_dir, 'dotted_.path')))
- self.assert_(os.path.exists(os.path.join(self.storage_dir, 'dotted.path/test')))
- self.assert_(os.path.exists(os.path.join(self.storage_dir, 'dotted.path/test_1')))
+ files = sorted(os.listdir(os.path.join(self.storage_dir, 'dotted.path')))
+ self.assertFalse(os.path.exists(os.path.join(self.storage_dir, 'dotted_.path')))
+ self.assertEqual(files[0], 'test')
+ self.assertTrue(re.match('test_%s' % FILE_SUFFIX_REGEX, files[1]))
+
def test_first_character_dot(self):
"""
@@ -180,10 +185,13 @@ class FileStoragePathParsing(TestCase):
self.assert_(os.path.exists(os.path.join(self.storage_dir, 'dotted.path/.test')))
# Before 2.6, a leading dot was treated as an extension, and so
# underscore gets added to beginning instead of end.
+ files = sorted(os.listdir(os.path.join(self.storage_dir, 'dotted.path')))
+ self.assertEqual(files[0], '.test')
if sys.version_info < (2, 6):
- self.assert_(os.path.exists(os.path.join(self.storage_dir, 'dotted.path/_1.test')))
+ self.assertTrue(re.match('_%s.test' % FILE_SUFFIX_REGEX, files[1]))
else:
- self.assert_(os.path.exists(os.path.join(self.storage_dir, 'dotted.path/.test_1')))
+ self.assertTrue(re.match('.test_%s' % FILE_SUFFIX_REGEX, files[1]))
+
if Image is not None:
class DimensionClosingBug(TestCase):
--- a/tests/modeltests/files/models.py
+++ b/tests/modeltests/files/models.py
@@ -90,8 +90,8 @@ True
>>> obj2 = Storage()
>>> obj2.normal.save('django_test.txt', ContentFile('more content'))
->>> obj2.normal
-<FieldFile: tests/django_test_1.txt>
+>>> obj2.normal # doctest: +ELLIPSIS
+<FieldFile: tests/django_test_....txt>
>>> obj2.normal.size
12
@@ -100,24 +100,26 @@ True
>>> from django.core.cache import cache
>>> cache.set('obj1', obj1)
>>> cache.set('obj2', obj2)
->>> cache.get('obj2').normal
-<FieldFile: tests/django_test_1.txt>
+>>> cache.get('obj2').normal # doctest: +ELLIPSIS
+<FieldFile: tests/django_test_....txt>
# Deleting an object deletes the file it uses, if there are no other objects
# still using that file.
>>> obj2.delete()
>>> obj2.normal.save('django_test.txt', ContentFile('more content'))
->>> obj2.normal
-<FieldFile: tests/django_test_1.txt>
+>>> obj2.normal # doctest: +ELLIPSIS
+<FieldFile: tests/django_test_....txt>
# Multiple files with the same name get _N appended to them.
>>> objs = [Storage() for i in range(3)]
>>> for o in objs:
... o.normal.save('multiple_files.txt', ContentFile('Same Content'))
->>> [o.normal for o in objs]
-[<FieldFile: tests/multiple_files.txt>, <FieldFile: tests/multiple_files_1.txt>, <FieldFile: tests/multiple_files_2.txt>]
+>>> [o.normal for o in objs] # doctest: +ELLIPSIS, +NORMALIZE_WHITESPACE
+[<FieldFile: tests/multiple_files.txt>,
+ <FieldFile: tests/multiple_files_....txt>,
+ <FieldFile: tests/multiple_files_....txt>]
>>> for o in objs:
... o.delete()
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