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python38
CVE-2023-27043-email-parsing-errors.patch
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File CVE-2023-27043-email-parsing-errors.patch of Package python38
--- Doc/library/email.utils.rst | 19 - Lib/email/utils.py | 151 +++++++- Lib/test/test_email/test_email.py | 187 +++++++++- Misc/NEWS.d/next/Library/2023-10-20-15-28-08.gh-issue-102988.dStNO7.rst | 8 4 files changed, 344 insertions(+), 21 deletions(-) --- a/Doc/library/email.utils.rst +++ b/Doc/library/email.utils.rst @@ -60,13 +60,18 @@ of the new API. begins with angle brackets, they are stripped off. -.. function:: parseaddr(address) +.. function:: parseaddr(address, *, strict=True) Parse address -- which should be the value of some address-containing field such as :mailheader:`To` or :mailheader:`Cc` -- into its constituent *realname* and *email address* parts. Returns a tuple of that information, unless the parse fails, in which case a 2-tuple of ``('', '')`` is returned. + If *strict* is true, use a strict parser which rejects malformed inputs. + + .. versionchanged:: 3.13 + Add *strict* optional parameter and reject malformed inputs by default. + .. function:: formataddr(pair, charset='utf-8') @@ -84,12 +89,15 @@ of the new API. Added the *charset* option. -.. function:: getaddresses(fieldvalues) +.. function:: getaddresses(fieldvalues, *, strict=True) This method returns a list of 2-tuples of the form returned by ``parseaddr()``. *fieldvalues* is a sequence of header field values as might be returned by - :meth:`Message.get_all <email.message.Message.get_all>`. Here's a simple - example that gets all the recipients of a message:: + :meth:`Message.get_all <email.message.Message.get_all>`. + + If *strict* is true, use a strict parser which rejects malformed inputs. + + Here's a simple example that gets all the recipients of a message:: from email.utils import getaddresses @@ -99,6 +107,9 @@ of the new API. resent_ccs = msg.get_all('resent-cc', []) all_recipients = getaddresses(tos + ccs + resent_tos + resent_ccs) + .. versionchanged:: 3.13 + Add *strict* optional parameter and reject malformed inputs by default. + .. function:: parsedate(date) --- a/Lib/email/utils.py +++ b/Lib/email/utils.py @@ -48,6 +48,7 @@ TICK = "'" specialsre = re.compile(r'[][\\()<>@,:;".]') escapesre = re.compile(r'[\\"]') + def _has_surrogates(s): """Return True if s contains surrogate-escaped binary data.""" # This check is based on the fact that unless there are surrogates, utf8 @@ -105,13 +106,128 @@ def formataddr(pair, charset='utf-8'): return '%s%s%s <%s>' % (quotes, name, quotes, address) return address + +def _iter_escaped_chars(addr): + pos = 0 + escape = False + for pos, ch in enumerate(addr): + if escape: + yield (pos, '\\' + ch) + escape = False + elif ch == '\\': + escape = True + else: + yield (pos, ch) + if escape: + yield (pos, '\\') + + +def _strip_quoted_realnames(addr): + """Strip real names between quotes.""" + if '"' not in addr: + # Fast path + return addr + + start = 0 + open_pos = None + result = [] + for pos, ch in _iter_escaped_chars(addr): + if ch == '"': + if open_pos is None: + open_pos = pos + else: + if start != open_pos: + result.append(addr[start:open_pos]) + start = pos + 1 + open_pos = None + + if start < len(addr): + result.append(addr[start:]) + + return ''.join(result) + + +supports_strict_parsing = True +def getaddresses(fieldvalues, *, strict=True): + """Return a list of (REALNAME, EMAIL) or ('','') for each fieldvalue. -def getaddresses(fieldvalues): - """Return a list of (REALNAME, EMAIL) for each fieldvalue.""" - all = COMMASPACE.join(fieldvalues) - a = _AddressList(all) - return a.addresslist + When parsing fails for a fieldvalue, a 2-tuple of ('', '') is returned in + its place. + + If strict is true, use a strict parser which rejects malformed inputs. + """ + + # 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 [('', + # '')] is returned in its place. This is done to avoid invalid output. + # + # Malformed input: getaddresses(['alice@example.com <bob@example.com>']) + # Invalid output: [('', 'alice@example.com'), ('', 'bob@example.com')] + # Safe output: [('', '')] + + if not strict: + all = COMMASPACE.join(str(v) for v in fieldvalues) + a = _AddressList(all) + return a.addresslist + + fieldvalues = [str(v) for v in fieldvalues] + fieldvalues = _pre_parse_validation(fieldvalues) + addr = COMMASPACE.join(fieldvalues) + a = _AddressList(addr) + result = _post_parse_validation(a.addresslist) + + # Treat output as invalid if the number of addresses is not equal to the + # expected number of addresses. + n = 0 + for v in fieldvalues: + # When a comma is used in the Real Name part it is not a deliminator. + # So strip those out before counting the commas. + v = _strip_quoted_realnames(v) + # Expected number of addresses: 1 + number of commas + n += 1 + v.count(',') + if len(result) != n: + return [('', '')] + + return result + + +def _check_parenthesis(addr): + # Ignore parenthesis in quoted real names. + addr = _strip_quoted_realnames(addr) + + opens = 0 + for pos, ch in _iter_escaped_chars(addr): + if ch == '(': + opens += 1 + elif ch == ')': + opens -= 1 + if opens < 0: + return False + return (opens == 0) + + +def _pre_parse_validation(email_header_fields): + accepted_values = [] + for v in email_header_fields: + if not _check_parenthesis(v): + v = "('', '')" + accepted_values.append(v) + + return accepted_values + + +def _post_parse_validation(parsed_email_header_tuples): + accepted_values = [] + # The parser would have parsed a correctly formatted domain-literal + # The existence of an [ after parsing indicates a parsing failure + for v in parsed_email_header_tuples: + if '[' in v[1]: + v = ('', '') + accepted_values.append(v) + + return accepted_values def _format_timetuple_and_zone(timetuple, zone): @@ -202,16 +318,33 @@ def parsedate_to_datetime(data): tzinfo=datetime.timezone(datetime.timedelta(seconds=tz))) -def parseaddr(addr): +def parseaddr(addr, *, strict=True): """ Parse addr into its constituent realname and email address parts. Return a tuple of realname and email address, unless the parse fails, in which case return a 2-tuple of ('', ''). + + If strict is True, use a strict parser which rejects malformed inputs. """ - addrs = _AddressList(addr).addresslist - if not addrs: - return '', '' + if not strict: + addrs = _AddressList(addr).addresslist + if not addrs: + return ('', '') + return addrs[0] + + if isinstance(addr, list): + addr = addr[0] + + if not isinstance(addr, str): + return ('', '') + + addr = _pre_parse_validation([addr])[0] + addrs = _post_parse_validation(_AddressList(addr).addresslist) + + if not addrs or len(addrs) > 1: + return ('', '') + return addrs[0] --- a/Lib/test/test_email/test_email.py +++ b/Lib/test/test_email/test_email.py @@ -16,6 +16,7 @@ from unittest.mock import patch import email import email.policy +import email.utils from email.charset import Charset from email.header import Header, decode_header, make_header @@ -3248,15 +3249,137 @@ Foo [('Al Person', 'aperson@dom.ain'), ('Bud Person', 'bperson@dom.ain')]) + def test_parsing_errors(self): + """Test for parsing errors from CVE-2023-27043 and CVE-2019-16056""" + alice = 'alice@example.org' + bob = 'bob@example.com' + empty = ('', '') + + # Test utils.getaddresses() and utils.parseaddr() on malformed email + # addresses: default behavior (strict=True) rejects malformed address, + # and strict=False which tolerates malformed address. + for invalid_separator, expected_non_strict in ( + ('(', [(f'<{bob}>', alice)]), + (')', [('', alice), empty, ('', bob)]), + ('<', [('', alice), empty, ('', bob), empty]), + ('>', [('', alice), empty, ('', bob)]), + ('[', [('', f'{alice}[<{bob}>]')]), + (']', [('', alice), empty, ('', bob)]), + ('@', [empty, empty, ('', bob)]), + (';', [('', alice), empty, ('', bob)]), + (':', [('', alice), ('', bob)]), + ('.', [('', alice + '.'), ('', bob)]), + ('"', [('', alice), ('', f'<{bob}>')]), + ): + address = f'{alice}{invalid_separator}<{bob}>' + with self.subTest(address=address): + self.assertEqual(utils.getaddresses([address]), + [empty]) + self.assertEqual(utils.getaddresses([address], strict=False), + expected_non_strict) + + self.assertEqual(utils.parseaddr([address]), + empty) + self.assertEqual(utils.parseaddr([address], strict=False), + ('', address)) + + # Comma (',') is treated differently depending on strict parameter. + # Comma without quotes. + address = f'{alice},<{bob}>' + self.assertEqual(utils.getaddresses([address]), + [('', alice), ('', bob)]) + self.assertEqual(utils.getaddresses([address], strict=False), + [('', alice), ('', bob)]) + self.assertEqual(utils.parseaddr([address]), + empty) + self.assertEqual(utils.parseaddr([address], strict=False), + ('', address)) + + # Real name between quotes containing comma. + address = '"Alice, alice@example.org" <bob@example.com>' + expected_strict = ('Alice, alice@example.org', 'bob@example.com') + self.assertEqual(utils.getaddresses([address]), [expected_strict]) + self.assertEqual(utils.getaddresses([address], strict=False), [expected_strict]) + self.assertEqual(utils.parseaddr([address]), expected_strict) + self.assertEqual(utils.parseaddr([address], strict=False), + ('', address)) + + # Valid parenthesis in comments. + address = 'alice@example.org (Alice)' + expected_strict = ('Alice', 'alice@example.org') + self.assertEqual(utils.getaddresses([address]), [expected_strict]) + self.assertEqual(utils.getaddresses([address], strict=False), [expected_strict]) + self.assertEqual(utils.parseaddr([address]), expected_strict) + self.assertEqual(utils.parseaddr([address], strict=False), + ('', address)) + + # Invalid parenthesis in comments. + address = 'alice@example.org )Alice(' + self.assertEqual(utils.getaddresses([address]), [empty]) + self.assertEqual(utils.getaddresses([address], strict=False), + [('', 'alice@example.org'), ('', ''), ('', 'Alice')]) + self.assertEqual(utils.parseaddr([address]), empty) + self.assertEqual(utils.parseaddr([address], strict=False), + ('', address)) + + # Two addresses with quotes separated by comma. + address = '"Jane Doe" <jane@example.net>, "John Doe" <john@example.net>' + self.assertEqual(utils.getaddresses([address]), + [('Jane Doe', 'jane@example.net'), + ('John Doe', 'john@example.net')]) + self.assertEqual(utils.getaddresses([address], strict=False), + [('Jane Doe', 'jane@example.net'), + ('John Doe', 'john@example.net')]) + self.assertEqual(utils.parseaddr([address]), empty) + self.assertEqual(utils.parseaddr([address], strict=False), + ('', address)) + + # Test email.utils.supports_strict_parsing attribute + self.assertEqual(email.utils.supports_strict_parsing, True) + def test_getaddresses_nasty(self): - eq = self.assertEqual - eq(utils.getaddresses(['foo: ;']), [('', '')]) - eq(utils.getaddresses( - ['[]*-- =~$']), - [('', ''), ('', ''), ('', '*--')]) - eq(utils.getaddresses( - ['foo: ;', '"Jason R. Mastaler" <jason@dom.ain>']), - [('', ''), ('Jason R. Mastaler', 'jason@dom.ain')]) + for addresses, expected in ( + (['"Sürname, Firstname" <to@example.com>'], + [('Sürname, Firstname', 'to@example.com')]), + + (['foo: ;'], + [('', '')]), + + (['foo: ;', '"Jason R. Mastaler" <jason@dom.ain>'], + [('', ''), ('Jason R. Mastaler', 'jason@dom.ain')]), + + ([r'Pete(A nice \) chap) <pete(his account)@silly.test(his host)>'], + [('Pete (A nice ) chap his account his host)', 'pete@silly.test')]), + + (['(Empty list)(start)Undisclosed recipients :(nobody(I know))'], + [('', '')]), + + (['Mary <@machine.tld:mary@example.net>, , jdoe@test . example'], + [('Mary', 'mary@example.net'), ('', ''), ('', 'jdoe@test.example')]), + + (['John Doe <jdoe@machine(comment). example>'], + [('John Doe (comment)', 'jdoe@machine.example')]), + + (['"Mary Smith: Personal Account" <smith@home.example>'], + [('Mary Smith: Personal Account', 'smith@home.example')]), + + (['Undisclosed recipients:;'], + [('', '')]), + + ([r'<boss@nil.test>, "Giant; \"Big\" Box" <bob@example.net>'], + [('', 'boss@nil.test'), ('Giant; "Big" Box', 'bob@example.net')]), + ): + with self.subTest(addresses=addresses): + self.assertEqual(utils.getaddresses(addresses), + expected) + self.assertEqual(utils.getaddresses(addresses, strict=False), + expected) + + addresses = ['[]*-- =~$'] + self.assertEqual(utils.getaddresses(addresses), + [('', '')]) + self.assertEqual(utils.getaddresses(addresses, strict=False), + [('', ''), ('', ''), ('', '*--')]) def test_getaddresses_embedded_comment(self): """Test proper handling of a nested comment""" @@ -3440,6 +3563,54 @@ multipart/report m = cls(*constructor, policy=email.policy.default) self.assertIs(m.policy, email.policy.default) + def test_iter_escaped_chars(self): + self.assertEqual(list(utils._iter_escaped_chars(r'a\\b\"c\\"d')), + [(0, 'a'), + (2, '\\\\'), + (3, 'b'), + (5, '\\"'), + (6, 'c'), + (8, '\\\\'), + (9, '"'), + (10, 'd')]) + self.assertEqual(list(utils._iter_escaped_chars('a\\')), + [(0, 'a'), (1, '\\')]) + + def test_strip_quoted_realnames(self): + def check(addr, expected): + self.assertEqual(utils._strip_quoted_realnames(addr), expected) + + check('"Jane Doe" <jane@example.net>, "John Doe" <john@example.net>', + ' <jane@example.net>, <john@example.net>') + check(r'"Jane \"Doe\"." <jane@example.net>', + ' <jane@example.net>') + + # special cases + check(r'before"name"after', 'beforeafter') + check(r'before"name"', 'before') + check(r'b"name"', 'b') # single char + check(r'"name"after', 'after') + check(r'"name"a', 'a') # single char + check(r'"name"', '') + + # no change + for addr in ( + 'Jane Doe <jane@example.net>, John Doe <john@example.net>', + 'lone " quote', + ): + self.assertEqual(utils._strip_quoted_realnames(addr), addr) + + + def test_check_parenthesis(self): + addr = 'alice@example.net' + self.assertTrue(utils._check_parenthesis(f'{addr} (Alice)')) + self.assertFalse(utils._check_parenthesis(f'{addr} )Alice(')) + self.assertFalse(utils._check_parenthesis(f'{addr} (Alice))')) + self.assertFalse(utils._check_parenthesis(f'{addr} ((Alice)')) + + # Ignore real name between quotes + self.assertTrue(utils._check_parenthesis(f'")Alice((" {addr}')) + # Test the iterator/generators class TestIterators(TestEmailBase): --- /dev/null +++ b/Misc/NEWS.d/next/Library/2023-10-20-15-28-08.gh-issue-102988.dStNO7.rst @@ -0,0 +1,8 @@ +:func:`email.utils.getaddresses` and :func:`email.utils.parseaddr` now +return ``('', '')`` 2-tuples in more situations where invalid email +addresses are encountered instead of potentially inaccurate values. Add +optional *strict* parameter to these two functions: use ``strict=False`` to +get the old behavior, accept malformed inputs. +``getattr(email.utils, 'supports_strict_parsing', False)`` can be use to check +if the *strict* paramater is available. Patch by Thomas Dwyer and Victor +Stinner to improve the CVE-2023-27043 fix.
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