[3.11] [CVE-2023-27043] gh-102988: Reject malformed addresses in email.parseaddr() (GH-111116) (#123767)

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.

(cherry picked from commit 4a153a1d3b)

Co-authored-by: Victor Stinner <vstinner@python.org>
Co-authored-by: Thomas Dwyer <github@tomd.tel>
This commit is contained in:
Petr Viktorin 2024-09-06 12:46:23 +02:00 committed by GitHub
parent 5752116ed7
commit bc4a703a93
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GPG key ID: B5690EEEBB952194
5 changed files with 371 additions and 21 deletions

View file

@ -48,6 +48,7 @@
specialsre = re.compile(r'[][\\()<>@,:;".]')
escapesre = re.compile(r'[\\"]')
def _has_surrogates(s):
"""Return True if s may contain surrogate-escaped binary data."""
# This check is based on the fact that unless there are surrogates, utf8
@ -106,12 +107,127 @@ def formataddr(pair, charset='utf-8'):
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 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 _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.
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):
@ -205,16 +321,33 @@ 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]

View file

@ -17,6 +17,7 @@
import email
import email.policy
import email.utils
from email.charset import Charset
from email.generator import Generator, DecodedGenerator, BytesGenerator
@ -3336,15 +3337,154 @@ 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" <bperson@dom.ain>',
'aperson@dom.ain (Al Person)',
'"Mariusz Felisiak" <to@example.com>',
]
),
[
('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=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"""
@ -3535,6 +3675,54 @@ def test_mime_classes_policy_argument(self):
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):