Attachment 926638 Details for Bug 1129952 – 1.4 patch

[patch] 1.4 patch

file-upload-1.4.diff (text/plain), 11.62 KB, created by Murray McAllister on 2014-08-14 04:45:58 UTC

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Creator: Murray McAllister

Created: 2014-08-14 04:45:58 UTC

Size: 11.62 KB

patch

obsolete

>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.
>
>diff --git a/django/core/files/storage.py b/django/core/files/storage.py
>index aa62175..3040764 100644
>--- a/django/core/files/storage.py
>+++ b/django/core/files/storage.py
>@@ -1,13 +1,13 @@
> import os
> import errno
> import urlparse
>-import itertools
> from datetime import datetime
> 
> 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, filepath_to_uri
> from django.utils.functional import LazyObject
> from django.utils.importlib import import_module
>@@ -63,13 +63,12 @@ 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
> 
>diff --git a/docs/howto/custom-file-storage.txt b/docs/howto/custom-file-storage.txt
>index 5f1dae1..ffcbe4a 100644
>--- a/docs/howto/custom-file-storage.txt
>+++ b/docs/howto/custom-file-storage.txt
>@@ -86,5 +86,13 @@ the provided filename into account. The ``name`` argument passed to this method
> 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.
>diff --git a/docs/ref/files/storage.txt b/docs/ref/files/storage.txt
>index b3f8909..252e8e4 100644
>--- a/docs/ref/files/storage.txt
>+++ b/docs/ref/files/storage.txt
>@@ -18,7 +18,7 @@ Django provides two convenient ways to access the current storage class:
> .. function:: get_storage_class([import_path=None])
> 
>     Returns a class or module which implements the storage API.
>-    
>+
>     When called without the ``import_path`` parameter ``get_storage_class``
>     will return the current default storage system as defined by
>     :setting:`DEFAULT_FILE_STORAGE`. If ``import_path`` is provided,
>@@ -35,9 +35,9 @@ The FileSystemStorage Class
>     basic file storage on a local filesystem. It inherits from
>     :class:`~django.core.files.storage.Storage` and provides implementations
>     for all the public methods thereof.
>-    
>+
>     .. note::
>-    
>+
>         The :class:`FileSystemStorage.delete` method will not raise
>         raise an exception if the given file name does not exist.
> 
>@@ -85,6 +85,16 @@ The Storage Class
>         available for new content to be written to on the target storage
>         system.
> 
>+        .. 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.
> 
>     .. method:: get_valid_name(name)
> 
>diff --git a/docs/releases/1.4.14.txt b/docs/releases/1.4.14.txt
>index 28390c9..6c140ee 100644
>--- a/docs/releases/1.4.14.txt
>+++ b/docs/releases/1.4.14.txt
>@@ -18,3 +18,23 @@ To remedy this, URL reversing now ensures that no URL starts with two slashes
> (//), replacing the second slash with its URL encoded counterpart (%2F). This
> approach ensures that semantics stay the same, while making the URL relative to
> the domain and not to the scheme.
>+
>+File upload denial-of-service
>+=============================
>+
>+Before this release, Django's file upload handing in its default configuration
>+may degrade to producing a huge number of ``os.stat()`` system calls when a
>+duplicate filename is uploaded. Since ``stat()`` may invoke IO, this may produce
>+a huge data-dependent slowdown that slowly worsens over time. The net result is
>+that given enough time, a user with the ability to upload files can cause poor
>+performance in the upload handler, eventually causing it to become very slow
>+simply by uploading 0-byte files. At this point, even a slow network connection
>+and few HTTP requests would be all that is necessary to make a site unavailable.
>+
>+We've remedied the issue by changing the algorithm for generating file names
>+if a file with the uploaded name already exists.
>+:meth:`Storage.get_available_name()
>+<django.core.files.storage.Storage.get_available_name>` now appends an
>+underscore plus a random 7 character alphanumeric string (e.g. ``"_x3a1gho"``),
>+rather than iterating through an underscore followed by a number (e.g. ``"_1"``,
>+``"_2"``, etc.).
>diff --git a/tests/modeltests/files/tests.py b/tests/modeltests/files/tests.py
>index 50017be..3864d27 100644
>--- a/tests/modeltests/files/tests.py
>+++ b/tests/modeltests/files/tests.py
>@@ -8,10 +8,14 @@ from django.core.files import File
> from django.core.files.base import ContentFile
> from django.core.files.uploadedfile import SimpleUploadedFile
> from django.test import TestCase
>+from django.utils import six
> 
> from .models import Storage, temp_storage, temp_storage_location
> 
> 
>+FILE_SUFFIX_REGEX = '[A-Za-z0-9]{7}'
>+
>+
> class FileTests(TestCase):
>     def tearDown(self):
>         shutil.rmtree(temp_storage_location)
>@@ -57,27 +61,28 @@ class FileTests(TestCase):
>         # Save another file with the same name.
>         obj2 = Storage()
>         obj2.normal.save("django_test.txt", ContentFile("more content"))
>-        self.assertEqual(obj2.normal.name, "tests/django_test_1.txt")
>+        obj2_name = obj2.normal.name
>+        six.assertRegex(self, obj2_name, "tests/django_test_%s.txt" % FILE_SUFFIX_REGEX)
>         self.assertEqual(obj2.normal.size, 12)
> 
>         # Push the objects into the cache to make sure they pickle properly
>         cache.set("obj1", obj1)
>         cache.set("obj2", obj2)
>-        self.assertEqual(cache.get("obj2").normal.name, "tests/django_test_1.txt")
>+        six.assertRegex(self, cache.get("obj2").normal.name, "tests/django_test_%s.txt" % FILE_SUFFIX_REGEX)
> 
>         # Deleting an object does not delete the file it uses.
>         obj2.delete()
>         obj2.normal.save("django_test.txt", ContentFile("more content"))
>-        self.assertEqual(obj2.normal.name, "tests/django_test_2.txt")
>+        self.assertNotEqual(obj2_name, obj2.normal.name)
>+        six.assertRegex(self, obj2.normal.name, "tests/django_test_%s.txt" % FILE_SUFFIX_REGEX)
> 
>         # Multiple files with the same name get _N appended to them.
>-        objs = [Storage() for i in range(3)]
>+        objs = [Storage() for i in range(2)]
>         for o in objs:
>             o.normal.save("multiple_files.txt", ContentFile("Same Content"))
>-        self.assertEqual(
>-            [o.normal.name for o in objs],
>-            ["tests/multiple_files.txt", "tests/multiple_files_1.txt", "tests/multiple_files_2.txt"]
>-        )
>+        names = [o.normal.name for o in objs]
>+        self.assertEqual(names[0], "tests/multiple_files.txt")
>+        six.assertRegex(self, names[1], "tests/multiple_files_%s.txt" % FILE_SUFFIX_REGEX)
>         for o in objs:
>             o.delete()
> 
>diff --git a/tests/regressiontests/file_storage/tests.py b/tests/regressiontests/file_storage/tests.py
>index 769e2c7..7c8027a 100644
>--- a/tests/regressiontests/file_storage/tests.py
>+++ b/tests/regressiontests/file_storage/tests.py
>@@ -23,7 +23,7 @@ from django.core.files.images import get_image_dimensions
> from django.core.files.storage import FileSystemStorage, get_storage_class
> from django.core.files.uploadedfile import UploadedFile
> from django.test import SimpleTestCase
>-from django.utils import unittest
>+from django.utils import six, unittest
> 
> # Try to import PIL in either of the two ways it can end up installed.
> # Checking for the existence of Image is enough for CPython, but
>@@ -37,6 +37,9 @@ except ImportError:
>         Image = None
> 
> 
>+FILE_SUFFIX_REGEX = '[A-Za-z0-9]{7}'
>+
>+
> class GetStorageClassTests(SimpleTestCase):
> 
>     def test_get_filesystem_storage(self):
>@@ -417,10 +420,9 @@ class FileSaveRaceConditionTest(unittest.TestCase):
>         self.thread.start()
>         name = self.save_file('conflict')
>         self.thread.join()
>-        self.assertTrue(self.storage.exists('conflict'))
>-        self.assertTrue(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')
>+        six.assertRegex(self, files[1], 'conflict_%s' % FILE_SUFFIX_REGEX)
> 
> class FileStoragePermissions(unittest.TestCase):
>     def setUp(self):
>@@ -457,9 +459,10 @@ class FileStoragePathParsing(unittest.TestCase):
>         self.storage.save('dotted.path/test', ContentFile("1"))
>         self.storage.save('dotted.path/test', ContentFile("2"))
> 
>+        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.assertTrue(os.path.exists(os.path.join(self.storage_dir, 'dotted.path/test')))
>-        self.assertTrue(os.path.exists(os.path.join(self.storage_dir, 'dotted.path/test_1')))
>+        self.assertEqual(files[0], 'test')
>+        six.assertRegex(self, files[1], 'test_%s' % FILE_SUFFIX_REGEX)
> 
>     def test_first_character_dot(self):
>         """
>@@ -472,10 +475,12 @@ class FileStoragePathParsing(unittest.TestCase):
>         self.assertTrue(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.assertTrue(os.path.exists(os.path.join(self.storage_dir, 'dotted.path/_1.test')))
>+            six.assertRegex(self, files[1], '_%s.test' % FILE_SUFFIX_REGEX)
>         else:
>-            self.assertTrue(os.path.exists(os.path.join(self.storage_dir, 'dotted.path/.test_1')))
>+            six.assertRegex(self, files[1], '.test_%s' % FILE_SUFFIX_REGEX)
> 
> class DimensionClosingBug(unittest.TestCase):
>     """

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