From d0e6cdedd272028b2ea16b34f15a91dafcc17bc8 Mon Sep 17 00:00:00 2001 From: Victor Stinner Date: Fri, 20 Oct 2023 15:26:41 +0200 Subject: [PATCH] gh-102988: email parseaddr() now rejects malformed address Detect email address parsing errors and return empty tuple to indicate the parsing error (old API). Add an optional 'strict' parameter to getaddresses() and parseaddr() functions. Patch by Thomas Dwyer. Co-Authored-By: Thomas Dwyer --- Doc/library/email.utils.rst | 17 ++- Doc/whatsnew/3.13.rst | 11 ++ Lib/email/utils.py | 121 ++++++++++++++-- Lib/test/test_email/test_email.py | 132 ++++++++++++++---- ...-10-20-15-28-08.gh-issue-102988.dStNO7.rst | 6 + 5 files changed, 251 insertions(+), 36 deletions(-) create mode 100644 Misc/NEWS.d/next/Library/2023-10-20-15-28-08.gh-issue-102988.dStNO7.rst diff --git a/Doc/library/email.utils.rst b/Doc/library/email.utils.rst index 345b64001c1ace1..5d03c08e7914d9c 100644 --- a/Doc/library/email.utils.rst +++ b/Doc/library/email.utils.rst @@ -65,6 +65,11 @@ of the new API. *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') @@ -82,12 +87,15 @@ 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 `. Here's a simple - example that gets all the recipients of a message:: + :meth:`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 @@ -97,6 +105,9 @@ 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) diff --git a/Doc/whatsnew/3.13.rst b/Doc/whatsnew/3.13.rst index 372e4a45468e68b..b4ba6a5dbe30c8d 100644 --- a/Doc/whatsnew/3.13.rst +++ b/Doc/whatsnew/3.13.rst @@ -192,6 +192,17 @@ doctest :attr:`doctest.TestResults.skipped` attributes. (Contributed by Victor Stinner in :gh:`108794`.) +email +----- + +* :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. + (Contributed by Thomas Dwyer for :gh:`102988` to improve the CVE-2023-27043 + fix.) + glob ---- diff --git a/Lib/email/utils.py b/Lib/email/utils.py index a49a8fa986ce0cf..1da8f7ad6dd9cbf 100644 --- a/Lib/email/utils.py +++ b/Lib/email/utils.py @@ -43,6 +43,7 @@ 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 @@ -103,12 +104,97 @@ def formataddr(pair, charset='utf-8'): return address +def _strip_quoted_realname(addr): + """Remove real name between quotes.""" + pos = 0 + start = None + remove = [] + while pos < len(addr): + if addr[pos] == '"': + if start is None: + start = pos + else: + remove.append((start, pos)) + start = None + pos += 1 + + if not remove: + return addr + + result = [] + pos = 0 + for start, stop in remove: + result.append(addr[pos:start]) + pos = stop + 1 + result.append(addr[pos:]) + + return ''.join(result) -def getaddresses(fieldvalues): - """Return a list of (REALNAME, EMAIL) for each fieldvalue.""" - all = COMMASPACE.join(str(v) for v in fieldvalues) - a = _AddressList(all) - return a.addresslist + +def getaddresses(fieldvalues, *, strict=True): + """Return a list of (REALNAME, EMAIL) or ('','') for each fieldvalue. + + 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. + In this case, 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 ']) + 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(v for v in 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_realname(v) + # Expected number of addresses: 1 + number of commas + n += 1 + v.count(',') + if len(result) != n: + return [('', '')] + + return result + + +def _pre_parse_validation(email_header_fields): + accepted_values = [] + for v in email_header_fields: + s = v.replace('\\(', '').replace('\\)', '') + if s.count('(') != s.count(')'): + 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): @@ -207,16 +293,33 @@ 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] diff --git a/Lib/test/test_email/test_email.py b/Lib/test/test_email/test_email.py index 512464f87162cde..db469f78ce55866 100644 --- a/Lib/test/test_email/test_email.py +++ b/Lib/test/test_email/test_email.py @@ -3320,32 +3320,116 @@ def test_getaddresses(self): [('Al Person', 'aperson@dom.ain'), ('Bud Person', 'bperson@dom.ain')]) - def test_getaddresses_comma_in_name(self): - """GH-106669 regression test.""" - self.assertEqual( - utils.getaddresses( - [ - '"Bud, Person" ', - 'aperson@dom.ain (Al Person)', - '"Mariusz Felisiak" ', - ] - ), - [ - ('Bud, Person', 'bperson@dom.ain'), - ('Al Person', 'aperson@dom.ain'), - ('Mariusz Felisiak', 'to@example.com'), - ], - ) + 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=True 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)) + + # Comma with quotes. + address = '"Alice, alice@example.org" ' + 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)) + + # Two addresses with quotes separated by comma. + address = '"Jane Doe" , "John Doe" ' + 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)) def test_getaddresses_nasty(self): - eq = self.assertEqual - eq(utils.getaddresses(['foo: ;']), [('', '')]) - eq(utils.getaddresses( - ['[]*-- =~$']), - [('', ''), ('', ''), ('', '*--')]) - eq(utils.getaddresses( - ['foo: ;', '"Jason R. Mastaler" ']), - [('', ''), ('Jason R. Mastaler', 'jason@dom.ain')]) + for addresses, expected in ( + (['"Sürname, Firstname" '], + [('Sürname, Firstname', 'to@example.com')]), + + (['foo: ;'], + [('', '')]), + + (['foo: ;', '"Jason R. Mastaler" '], + [('', ''), ('Jason R. Mastaler', 'jason@dom.ain')]), + + ([r'Pete(A nice \) chap) '], + [('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 '], + [('John Doe (comment)', 'jdoe@machine.example')]), + + (['"Mary Smith: Personal Account" '], + [('Mary Smith: Personal Account', 'smith@home.example')]), + + (['Undisclosed recipients:;'], + [('', '')]), + + ([r', "Giant; \"Big\" Box" '], + [('', '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""" diff --git a/Misc/NEWS.d/next/Library/2023-10-20-15-28-08.gh-issue-102988.dStNO7.rst b/Misc/NEWS.d/next/Library/2023-10-20-15-28-08.gh-issue-102988.dStNO7.rst new file mode 100644 index 000000000000000..d4703588cf12a80 --- /dev/null +++ b/Misc/NEWS.d/next/Library/2023-10-20-15-28-08.gh-issue-102988.dStNO7.rst @@ -0,0 +1,6 @@ +: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. Patch by Thomas Dwyer to +improve the CVE-2023-27043 fix.