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import os
from django.core.exceptions import SuspiciousFileOperation
from django.core.files.base import ContentFile
from django.core.files.storage import FileSystemStorage, Storage
from django.db.models import FileField
from django.test import SimpleTestCase
class AWSS3Storage(Storage):
"""
Simulate an AWS S3 storage which uses Unix-like paths and allows any
characters in file names but where there aren't actual folders but just
keys.
"""
prefix = 'mys3folder/'
def _save(self, name, content):
"""
This method is important to test that Storage.save() doesn't replace
'\' with '/' (rather FileSystemStorage.save() does).
"""
return name
def get_valid_name(self, name):
return name
def get_available_name(self, name, max_length=None):
return name
def generate_filename(self, filename):
"""
This is the method that's important to override when using S3 so that
os.path() isn't called, which would break S3 keys.
"""
return self.prefix + self.get_valid_name(filename)
class GenerateFilenameStorageTests(SimpleTestCase):
def test_storage_dangerous_paths(self):
candidates = [
('/tmp/..', '..'),
('/tmp/.', '.'),
('', ''),
]
s = FileSystemStorage()
msg = "Could not derive file name from '%s'"
for file_name, base_name in candidates:
with self.subTest(file_name=file_name):
with self.assertRaisesMessage(SuspiciousFileOperation, msg % base_name):
s.get_available_name(file_name)
with self.assertRaisesMessage(SuspiciousFileOperation, msg % base_name):
s.generate_filename(file_name)
def test_storage_dangerous_paths_dir_name(self):
candidates = [
('tmp/../path', 'tmp/..'),
('tmp\\..\\path', 'tmp/..'),
('/tmp/../path', '/tmp/..'),
('\\tmp\\..\\path', '/tmp/..'),
]
s = FileSystemStorage()
for file_name, path in candidates:
msg = "Detected path traversal attempt in '%s'" % path
with self.subTest(file_name=file_name):
with self.assertRaisesMessage(SuspiciousFileOperation, msg):
s.get_available_name(file_name)
with self.assertRaisesMessage(SuspiciousFileOperation, msg):
s.generate_filename(file_name)
def test_filefield_dangerous_filename(self):
candidates = [
('..', 'some/folder/..'),
('.', 'some/folder/.'),
('', 'some/folder/'),
('???', '???'),
('$.$.$', '$.$.$'),
]
f = FileField(upload_to='some/folder/')
for file_name, msg_file_name in candidates:
msg = f"Could not derive file name from '{msg_file_name}'"
with self.subTest(file_name=file_name):
with self.assertRaisesMessage(SuspiciousFileOperation, msg):
f.generate_filename(None, file_name)
def test_filefield_dangerous_filename_dot_segments(self):
f = FileField(upload_to='some/folder/')
msg = "Detected path traversal attempt in 'some/folder/../path'"
with self.assertRaisesMessage(SuspiciousFileOperation, msg):
f.generate_filename(None, '../path')
def test_filefield_generate_filename_absolute_path(self):
f = FileField(upload_to='some/folder/')
candidates = [
'/tmp/path',
'/tmp/../path',
]
for file_name in candidates:
msg = f"Detected path traversal attempt in '{file_name}'"
with self.subTest(file_name=file_name):
with self.assertRaisesMessage(SuspiciousFileOperation, msg):
f.generate_filename(None, file_name)
def test_filefield_generate_filename(self):
f = FileField(upload_to='some/folder/')
self.assertEqual(
f.generate_filename(None, 'test with space.txt'),
os.path.normpath('some/folder/test_with_space.txt')
)
def test_filefield_generate_filename_with_upload_to(self):
def upload_to(instance, filename):
return 'some/folder/' + filename
f = FileField(upload_to=upload_to)
self.assertEqual(
f.generate_filename(None, 'test with space.txt'),
os.path.normpath('some/folder/test_with_space.txt')
)
def test_filefield_generate_filename_upload_to_overrides_dangerous_filename(self):
def upload_to(instance, filename):
return 'test.txt'
f = FileField(upload_to=upload_to)
candidates = [
'/tmp/.',
'/tmp/..',
'/tmp/../path',
'/tmp/path',
'some/folder/',
'some/folder/.',
'some/folder/..',
'some/folder/???',
'some/folder/$.$.$',
'some/../test.txt',
'',
]
for file_name in candidates:
with self.subTest(file_name=file_name):
self.assertEqual(f.generate_filename(None, file_name), 'test.txt')
def test_filefield_generate_filename_upload_to_absolute_path(self):
def upload_to(instance, filename):
return '/tmp/' + filename
f = FileField(upload_to=upload_to)
candidates = [
'path',
'../path',
'???',
'$.$.$',
]
for file_name in candidates:
msg = f"Detected path traversal attempt in '/tmp/{file_name}'"
with self.subTest(file_name=file_name):
with self.assertRaisesMessage(SuspiciousFileOperation, msg):
f.generate_filename(None, file_name)
def test_filefield_generate_filename_upload_to_dangerous_filename(self):
def upload_to(instance, filename):
return '/tmp/' + filename
f = FileField(upload_to=upload_to)
candidates = ['..', '.', '']
for file_name in candidates:
msg = f"Could not derive file name from '/tmp/{file_name}'"
with self.subTest(file_name=file_name):
with self.assertRaisesMessage(SuspiciousFileOperation, msg):
f.generate_filename(None, file_name)
def test_filefield_awss3_storage(self):
"""
Simulate a FileField with an S3 storage which uses keys rather than
folders and names. FileField and Storage shouldn't have any os.path()
calls that break the key.
"""
storage = AWSS3Storage()
folder = 'not/a/folder/'
f = FileField(upload_to=folder, storage=storage)
key = 'my-file-key\\with odd characters'
data = ContentFile('test')
expected_key = AWSS3Storage.prefix + folder + key
# Simulate call to f.save()
result_key = f.generate_filename(None, key)
self.assertEqual(result_key, expected_key)
result_key = storage.save(result_key, data)
self.assertEqual(result_key, expected_key)
# Repeat test with a callable.
def upload_to(instance, filename):
# Return a non-normalized path on purpose.
return folder + filename
f = FileField(upload_to=upload_to, storage=storage)
# Simulate call to f.save()
result_key = f.generate_filename(None, key)
self.assertEqual(result_key, expected_key)
result_key = storage.save(result_key, data)
self.assertEqual(result_key, expected_key)
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