python39/SOURCES/00415-cve-2023-27043-gh-102988-reject-malformed-addresses-in-email-parseaddr-111116.patch

249 lines
9.0 KiB
Diff

From 4df4fad359c280f2328b98ea9b4414f244624a58 Mon Sep 17 00:00:00 2001
From: Lumir Balhar <lbalhar@redhat.com>
Date: Mon, 18 Dec 2023 20:15:33 +0100
Subject: [PATCH] Make it possible to disable strict parsing in email module
---
Doc/library/email.utils.rst | 26 +++++++++++
Lib/email/utils.py | 54 ++++++++++++++++++++++-
Lib/test/test_email/test_email.py | 72 ++++++++++++++++++++++++++++++-
3 files changed, 149 insertions(+), 3 deletions(-)
diff --git a/Doc/library/email.utils.rst b/Doc/library/email.utils.rst
index d1e1898591..7aef773b5f 100644
--- a/Doc/library/email.utils.rst
+++ b/Doc/library/email.utils.rst
@@ -69,6 +69,19 @@ of the new API.
If *strict* is true, use a strict parser which rejects malformed inputs.
+ The default setting for *strict* is set to ``True``, but you can override
+ it by setting the environment variable ``PYTHON_EMAIL_DISABLE_STRICT_ADDR_PARSING``
+ to non-empty string.
+
+ Additionally, you can permanently set the default value for *strict* to
+ ``False`` by creating the configuration file ``/etc/python/email.cfg``
+ with the following content:
+
+ .. code-block:: ini
+
+ [email_addr_parsing]
+ PYTHON_EMAIL_DISABLE_STRICT_ADDR_PARSING = true
+
.. versionchanged:: 3.9.20
Add *strict* optional parameter and reject malformed inputs by default.
@@ -97,6 +110,19 @@ of the new API.
If *strict* is true, use a strict parser which rejects malformed inputs.
+ The default setting for *strict* is set to ``True``, but you can override
+ it by setting the environment variable ``PYTHON_EMAIL_DISABLE_STRICT_ADDR_PARSING``
+ to non-empty string.
+
+ Additionally, you can permanently set the default value for *strict* to
+ ``False`` by creating the configuration file ``/etc/python/email.cfg``
+ with the following content:
+
+ .. code-block:: ini
+
+ [email_addr_parsing]
+ PYTHON_EMAIL_DISABLE_STRICT_ADDR_PARSING = true
+
Here's a simple example that gets all the recipients of a message::
from email.utils import getaddresses
diff --git a/Lib/email/utils.py b/Lib/email/utils.py
index f83b7e5d7e..b8e90ceb8e 100644
--- a/Lib/email/utils.py
+++ b/Lib/email/utils.py
@@ -48,6 +48,46 @@ TICK = "'"
specialsre = re.compile(r'[][\\()<>@,:;".]')
escapesre = re.compile(r'[\\"]')
+_EMAIL_CONFIG_FILE = "/etc/python/email.cfg"
+_cached_strict_addr_parsing = None
+
+
+def _use_strict_email_parsing():
+ """"Cache implementation for _cached_strict_addr_parsing"""
+ global _cached_strict_addr_parsing
+ if _cached_strict_addr_parsing is None:
+ _cached_strict_addr_parsing = _use_strict_email_parsing_impl()
+ return _cached_strict_addr_parsing
+
+
+def _use_strict_email_parsing_impl():
+ """Returns True if strict email parsing is not disabled by
+ config file or env variable.
+ """
+ disabled = bool(os.environ.get("PYTHON_EMAIL_DISABLE_STRICT_ADDR_PARSING"))
+ if disabled:
+ return False
+
+ try:
+ file = open(_EMAIL_CONFIG_FILE)
+ except FileNotFoundError:
+ pass
+ else:
+ with file:
+ import configparser
+ config = configparser.ConfigParser(
+ interpolation=None,
+ comment_prefixes=('#', ),
+
+ )
+ config.read_file(file)
+ disabled = config.getboolean('email_addr_parsing', "PYTHON_EMAIL_DISABLE_STRICT_ADDR_PARSING", fallback=None)
+
+ if disabled:
+ return False
+
+ return True
+
def _has_surrogates(s):
"""Return True if s contains surrogate-escaped binary data."""
@@ -149,7 +189,7 @@ def _strip_quoted_realnames(addr):
supports_strict_parsing = True
-def getaddresses(fieldvalues, *, strict=True):
+def getaddresses(fieldvalues, *, strict=None):
"""Return a list of (REALNAME, EMAIL) or ('','') for each fieldvalue.
When parsing fails for a fieldvalue, a 2-tuple of ('', '') is returned in
@@ -158,6 +198,11 @@ def getaddresses(fieldvalues, *, strict=True):
If strict is true, use a strict parser which rejects malformed inputs.
"""
+ # If default is used, it's True unless disabled
+ # by env variable or config file.
+ if strict == None:
+ strict = _use_strict_email_parsing()
+
# If strict is true, if the resulting list of parsed addresses is greater
# than the number of fieldvalues in the input list, a parsing error has
# occurred and consequently a list containing a single empty 2-tuple [('',
@@ -330,7 +375,7 @@ def parsedate_to_datetime(data):
tzinfo=datetime.timezone(datetime.timedelta(seconds=tz)))
-def parseaddr(addr, *, strict=True):
+def parseaddr(addr, *, strict=None):
"""
Parse addr into its constituent realname and email address parts.
@@ -339,6 +384,11 @@ def parseaddr(addr, *, strict=True):
If strict is True, use a strict parser which rejects malformed inputs.
"""
+ # If default is used, it's True unless disabled
+ # by env variable or config file.
+ if strict == None:
+ strict = _use_strict_email_parsing()
+
if not strict:
addrs = _AddressList(addr).addresslist
if not addrs:
diff --git a/Lib/test/test_email/test_email.py b/Lib/test/test_email/test_email.py
index ce36efc1b1..05ea201b68 100644
--- a/Lib/test/test_email/test_email.py
+++ b/Lib/test/test_email/test_email.py
@@ -7,6 +7,9 @@ import time
import base64
import unittest
import textwrap
+import contextlib
+import tempfile
+import os
from io import StringIO, BytesIO
from itertools import chain
@@ -41,7 +44,7 @@ from email import iterators
from email import base64mime
from email import quoprimime
-from test.support import unlink, start_threads
+from test.support import unlink, start_threads, EnvironmentVarGuard, swap_attr
from test.test_email import openfile, TestEmailBase
# These imports are documented to work, but we are testing them using a
@@ -3313,6 +3316,73 @@ Foo
# Test email.utils.supports_strict_parsing attribute
self.assertEqual(email.utils.supports_strict_parsing, True)
+ def test_parsing_errors_strict_set_via_env_var(self):
+ address = 'alice@example.org )Alice('
+ empty = ('', '')
+
+ # Reset cached default value to make the function
+ # reload the config file provided below.
+ utils._cached_strict_addr_parsing = None
+
+ # Strict disabled via env variable, old behavior expected
+ with EnvironmentVarGuard() as environ:
+ environ["PYTHON_EMAIL_DISABLE_STRICT_ADDR_PARSING"] = "1"
+
+ self.assertEqual(utils.getaddresses([address]),
+ [('', 'alice@example.org'), ('', ''), ('', 'Alice')])
+ self.assertEqual(utils.parseaddr([address]), ('', address))
+
+ # Clear cache again
+ utils._cached_strict_addr_parsing = None
+
+ # Default strict=True, empty result expected
+ self.assertEqual(utils.getaddresses([address]), [empty])
+ self.assertEqual(utils.parseaddr([address]), empty)
+
+ # Clear cache again
+ utils._cached_strict_addr_parsing = None
+
+ # Empty string in env variable = strict parsing enabled (default)
+ with EnvironmentVarGuard() as environ:
+ environ["PYTHON_EMAIL_DISABLE_STRICT_ADDR_PARSING"] = ""
+
+ # Default strict=True, empty result expected
+ self.assertEqual(utils.getaddresses([address]), [empty])
+ self.assertEqual(utils.parseaddr([address]), empty)
+
+ @contextlib.contextmanager
+ def _email_strict_parsing_conf(self):
+ """Context for the given email strict parsing configured in config file"""
+ with tempfile.TemporaryDirectory() as tmpdirname:
+ filename = os.path.join(tmpdirname, 'conf.cfg')
+ with swap_attr(utils, "_EMAIL_CONFIG_FILE", filename):
+ with open(filename, 'w') as file:
+ file.write('[email_addr_parsing]\n')
+ file.write('PYTHON_EMAIL_DISABLE_STRICT_ADDR_PARSING = true')
+ utils._EMAIL_CONFIG_FILE = filename
+ yield
+
+ def test_parsing_errors_strict_disabled_via_config_file(self):
+ address = 'alice@example.org )Alice('
+ empty = ('', '')
+
+ # Reset cached default value to make the function
+ # reload the config file provided below.
+ utils._cached_strict_addr_parsing = None
+
+ # Strict disabled via config file, old results expected
+ with self._email_strict_parsing_conf():
+ self.assertEqual(utils.getaddresses([address]),
+ [('', 'alice@example.org'), ('', ''), ('', 'Alice')])
+ self.assertEqual(utils.parseaddr([address]), ('', address))
+
+ # Clear cache again
+ utils._cached_strict_addr_parsing = None
+
+ # Default strict=True, empty result expected
+ self.assertEqual(utils.getaddresses([address]), [empty])
+ self.assertEqual(utils.parseaddr([address]), empty)
+
def test_getaddresses_nasty(self):
for addresses, expected in (
(['"Sürname, Firstname" <to@example.com>'],
--
2.43.0