openstack/swift
Code Issues Proposed changes

Do not use pickle for serialization in memcache, but JSON

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We don't want to use pickle as it can execute arbitrary code. JSON is
safer. However, note that it supports serialization for only some
specific subset of object types; this should be enough for what we need,
though.

To avoid issues on upgrades (unability to read pickled values, and cache
poisoning for old servers not understanding JSON), we add a
memcache_serialization_support configuration option, with the following
values:

 0 = older, insecure pickle serialization
 1 = json serialization but pickles can still be read (still insecure)
 2 = json serialization only (secure and the default)

To avoid an instant full cache flush, existing installations should
upgrade with 0, then set to 1 and reload, then after some time (24
hours) set to 2 and reload. Support for 0 and 1 will be removed in
future versions.

Part of bug 1006414.

Change-Id: Id7d6d547b103b4f23ebf5be98b88f09ec6027ce4
This commit is contained in:
Vincent Untz 2012-06-21 14:37:41 +02:00
parent ef3f8bb335
commit e1ff51c045
7 changed files with 125 additions and 17 deletions
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15
doc/manpages/proxy-server.conf.5
View File

@ -213,6 +213,21 @@ Logging address. The default is /dev/log.
Enables the ability to log request headers. The default is False.
.IP \fBmemcache_servers\fR
If not set in the configuration file, the value for memcache_servers will be read from /etc/swift/memcache.conf (see memcache.conf-sample) or lacking that file, it will default to the value below. You can specify multiple servers separated with commas, as in: 10.1.2.3:11211,10.1.2.4:11211. This can be a list separated by commas. The default is 127.0.0.1:11211.
.IP \fBmemcache_serialization_support\fR
This sets how memcache values are serialized and deserialized:
.RE
.PD 0
.RS 10
.IP "0 = older, insecure pickle serialization"
.IP "1 = json serialization but pickles can still be read (still insecure)"
.IP "2 = json serialization only (secure and the default)"
.RE
.RS 10
To avoid an instant full cache flush, existing installations should upgrade with 0, then set to 1 and reload, then after some time (24 hours) set to 2 and reload. In the future, the ability to use pickle serialization will be removed.
If not set in the configuration file, the value for memcache_serialization_support will be read from /etc/swift/memcache.conf if it exists (see memcache.conf-sample). Otherwise, the default value as indicated above will be used.
.RE

10
etc/memcache.conf-sample
View File

@ -3,3 +3,13 @@
# several other conf files under [filter:cache] for example. You can specify
# multiple servers separated with commas, as in: 10.1.2.3:11211,10.1.2.4:11211
# memcache_servers = 127.0.0.1:11211
#
# Sets how memcache values are serialized and deserialized:
# 0 = older, insecure pickle serialization
# 1 = json serialization but pickles can still be read (still insecure)
# 2 = json serialization only (secure and the default)
# To avoid an instant full cache flush, existing installations should
# upgrade with 0, then set to 1 and reload, then after some time (24 hours)
# set to 2 and reload.
# In the future, the ability to use pickle serialization will be removed.
# memcache_serialization_support = 2

12
etc/proxy-server.conf-sample
View File

@ -167,6 +167,18 @@ use = egg:swift#memcache
# default to the value below. You can specify multiple servers separated with
# commas, as in: 10.1.2.3:11211,10.1.2.4:11211
# memcache_servers = 127.0.0.1:11211
#
# Sets how memcache values are serialized and deserialized:
# 0 = older, insecure pickle serialization
# 1 = json serialization but pickles can still be read (still insecure)
# 2 = json serialization only (secure and the default)
# If not set here, the value for memcache_serialization_support will be read
# from /etc/swift/memcache.conf (see memcache.conf-sample).
# To avoid an instant full cache flush, existing installations should
# upgrade with 0, then set to 1 and reload, then after some time (24 hours)
# set to 2 and reload.
# In the future, the ability to use pickle serialization will be removed.
# memcache_serialization_support = 2
[filter:ratelimit]
use = egg:swift#ratelimit

48
swift/common/memcached.py
View File

@ -27,11 +27,17 @@ import time
from bisect import bisect
from hashlib import md5
try:
import simplejson as json
except ImportError:
import json
DEFAULT_MEMCACHED_PORT = 11211
CONN_TIMEOUT = 0.3
IO_TIMEOUT = 2.0
PICKLE_FLAG = 1
JSON_FLAG = 2
NODE_WEIGHT = 50
PICKLE_PROTOCOL = 2
TRY_COUNT = 3
@ -57,7 +63,8 @@ class MemcacheRing(object):
"""
def __init__(self, servers, connect_timeout=CONN_TIMEOUT,
io_timeout=IO_TIMEOUT, tries=TRY_COUNT):
io_timeout=IO_TIMEOUT, tries=TRY_COUNT,
allow_pickle=False, allow_unpickle=False):
self._ring = {}
self._errors = dict(((serv, []) for serv in servers))
self._error_limited = dict(((serv, 0) for serv in servers))
@ -69,6 +76,8 @@ class MemcacheRing(object):
self._client_cache = dict(((server, []) for server in servers))
self._connect_timeout = connect_timeout
self._io_timeout = io_timeout
self._allow_pickle = allow_pickle
self._allow_unpickle = allow_unpickle or allow_pickle
def _exception_occurred(self, server, e, action='talking'):
if isinstance(e, socket.timeout):
@ -130,16 +139,21 @@ class MemcacheRing(object):
:param key: key
:param value: value
:param serialize: if True, value is pickled before sending to memcache
:param serialize: if True, value is serialized with JSON before sending
to memcache, or with pickle if configured to use
pickle instead of JSON (to avoid cache poisoning)
:param timeout: ttl in memcache
"""
key = md5hash(key)
if timeout > 0:
timeout += time.time()
flags = 0
if serialize:
if serialize and self._allow_pickle:
value = pickle.dumps(value, PICKLE_PROTOCOL)
flags |= PICKLE_FLAG
elif serialize:
value = json.dumps(value)
flags |= JSON_FLAG
for (server, fp, sock) in self._get_conns(key):
try:
sock.sendall('set %s %d %d %s noreply\r\n%s\r\n' % \
@ -151,8 +165,9 @@ class MemcacheRing(object):
def get(self, key):
"""
Gets the object specified by key. It will also unpickle the object
before returning if it is pickled in memcache.
Gets the object specified by key. It will also unserialize the object
before returning if it is serialized in memcache with JSON, or if it
is pickled and unpickling is allowed.
:param key: key
:returns: value of the key in memcache
@ -168,7 +183,12 @@ class MemcacheRing(object):
size = int(line[3])
value = fp.read(size)
if int(line[2]) & PICKLE_FLAG:
value = pickle.loads(value)
if self._allow_unpickle:
value = pickle.loads(value)
else:
value = None
elif int(line[2]) & JSON_FLAG:
value = json.loads(value)
fp.readline()
line = fp.readline().strip().split()
self._return_conn(server, fp, sock)
@ -258,7 +278,9 @@ class MemcacheRing(object):
:param mapping: dictonary of keys and values to be set in memcache
:param servery_key: key to use in determining which server in the ring
is used
:param serialize: if True, value is pickled before sending to memcache
:param serialize: if True, value is serialized with JSON before sending
to memcache, or with pickle if configured to use
pickle instead of JSON (to avoid cache poisoning)
:param timeout: ttl for memcache
"""
server_key = md5hash(server_key)
@ -268,9 +290,12 @@ class MemcacheRing(object):
for key, value in mapping.iteritems():
key = md5hash(key)
flags = 0
if serialize:
if serialize and self._allow_pickle:
value = pickle.dumps(value, PICKLE_PROTOCOL)
flags |= PICKLE_FLAG
elif serialize:
value = json.dumps(value)
flags |= JSON_FLAG
msg += ('set %s %d %d %s noreply\r\n%s\r\n' %
(key, flags, timeout, len(value), value))
for (server, fp, sock) in self._get_conns(server_key):
@ -302,7 +327,12 @@ class MemcacheRing(object):
size = int(line[3])
value = fp.read(size)
if int(line[2]) & PICKLE_FLAG:
value = pickle.loads(value)
if self._allow_unpickle:
value = pickle.loads(value)
else:
value = None
elif int(line[2]) & JSON_FLAG:
value = json.loads(value)
responses[line[1]] = value
fp.readline()
line = fp.readline().strip().split()

30
swift/common/middleware/memcache.py
View File

@ -27,20 +27,36 @@ class MemcacheMiddleware(object):
def __init__(self, app, conf):
self.app = app
self.memcache_servers = conf.get('memcache_servers')
if not self.memcache_servers:
serialization_format = conf.get('memcache_serialization_support')
if not self.memcache_servers or serialization_format is None:
path = os.path.join(conf.get('swift_dir', '/etc/swift'),
'memcache.conf')
memcache_conf = ConfigParser()
if memcache_conf.read(path):
try:
self.memcache_servers = \
memcache_conf.get('memcache', 'memcache_servers')
except (NoSectionError, NoOptionError):
pass
if not self.memcache_servers:
try:
self.memcache_servers = \
memcache_conf.get('memcache', 'memcache_servers')
except (NoSectionError, NoOptionError):
pass
if serialization_format is None:
try:
serialization_format = \
memcache_conf.get('memcache',
'memcache_serialization_support')
except (NoSectionError, NoOptionError):
pass
if not self.memcache_servers:
self.memcache_servers = '127.0.0.1:11211'
if serialization_format is None:
serialization_format = 2
self.memcache = MemcacheRing(
[s.strip() for s in self.memcache_servers.split(',') if s.strip()])
[s.strip() for s in self.memcache_servers.split(',') if s.strip()],
allow_pickle=(serialization_format == 0),
allow_unpickle=(serialization_format <= 1))
def __call__(self, env, start_response):
env['swift.cache'] = self.memcache

5
test/unit/common/middleware/test_memcache.py
View File

@ -47,6 +47,8 @@ class SetConfigParser(object):
if section == 'memcache':
if option == 'memcache_servers':
return '1.2.3.4:5'
elif option == 'memcache_serialization_support':
return '2'
else:
raise NoOptionError(option)
else:
@ -86,7 +88,8 @@ class TestCacheMiddleware(unittest.TestCase):
exc = None
try:
app = memcache.MemcacheMiddleware(
FakeApp(), {'memcache_servers': '1.2.3.4:5'})
FakeApp(), {'memcache_servers': '1.2.3.4:5',
'memcache_serialization_support': '2'})
except Exception, err:
exc = err
finally:

22
test/unit/common/test_memcached.py
View File

@ -1,3 +1,4 @@
# -*- coding: utf8 -*-
# Copyright (c) 2010-2012 OpenStack, LLC.
#
# Licensed under the Apache License, Version 2.0 (the "License");
@ -161,6 +162,9 @@ class TestMemcached(unittest.TestCase):
self.assertEquals(memcache_client.get('some_key'), [1, 2, 3])
memcache_client.set('some_key', [4, 5, 6])
self.assertEquals(memcache_client.get('some_key'), [4, 5, 6])
memcache_client.set('some_key', ['simple str', 'utf8 str éà'])
# As per http://wiki.openstack.org/encoding, we should expect to have unicode
self.assertEquals(memcache_client.get('some_key'), ['simple str', u'utf8 str éà'])
self.assert_(float(mock.cache.values()[0][1]) == 0)
esttimeout = time.time() + 10
memcache_client.set('some_key', [1, 2, 3], timeout=10)
@ -239,6 +243,24 @@ class TestMemcached(unittest.TestCase):
self.assertEquals(memcache_client.get_multi(('some_key2', 'some_key1',
'not_exists'), 'multi_key'), [[4, 5, 6], [1, 2, 3], None])
def test_serialization(self):
memcache_client = memcached.MemcacheRing(['1.2.3.4:11211'],
allow_pickle=True)
mock = MockMemcached()
memcache_client._client_cache['1.2.3.4:11211'] = [(mock, mock)] * 2
memcache_client.set('some_key', [1, 2, 3])
self.assertEquals(memcache_client.get('some_key'), [1, 2, 3])
memcache_client._allow_pickle = False
memcache_client._allow_unpickle = True
self.assertEquals(memcache_client.get('some_key'), [1, 2, 3])
memcache_client._allow_unpickle = False
self.assertEquals(memcache_client.get('some_key'), None)
memcache_client.set('some_key', [1, 2, 3])
self.assertEquals(memcache_client.get('some_key'), [1, 2, 3])
memcache_client._allow_unpickle = True
self.assertEquals(memcache_client.get('some_key'), [1, 2, 3])
memcache_client._allow_pickle = True
self.assertEquals(memcache_client.get('some_key'), [1, 2, 3])
if __name__ == '__main__':
unittest.main()