bpo-38576: Disallow control characters in hostnames in http.client (GH-18995)

Add host validation for control characters for more CVE-2019-18348 protection.
This commit is contained in:
Ashwin Ramaswami 2020-03-14 14:56:06 -04:00 committed by GitHub
parent 6672c16b1d
commit 9165addc22
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GPG Key ID: 4AEE18F83AFDEB23
4 changed files with 57 additions and 3 deletions

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@ -828,6 +828,8 @@ class HTTPConnection:
(self.host, self.port) = self._get_hostport(host, port)
self._validate_host(self.host)
# This is stored as an instance variable to allow unit
# tests to replace it with a suitable mockup
self._create_connection = socket.create_connection
@ -1183,6 +1185,14 @@ class HTTPConnection:
raise InvalidURL(f"URL can't contain control characters. {url!r} "
f"(found at least {match.group()!r})")
def _validate_host(self, host):
"""Validate a host so it doesn't contain control characters."""
# Prevent CVE-2019-18348.
match = _contains_disallowed_url_pchar_re.search(host)
if match:
raise InvalidURL(f"URL can't contain control characters. {host!r} "
f"(found at least {match.group()!r})")
def putheader(self, header, *values):
"""Send a request header line to the server.

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@ -1155,7 +1155,7 @@ class BasicTest(TestCase):
thread.join()
self.assertEqual(result, b"proxied data\n")
def test_putrequest_override_validation(self):
def test_putrequest_override_domain_validation(self):
"""
It should be possible to override the default validation
behavior in putrequest (bpo-38216).
@ -1168,6 +1168,17 @@ class BasicTest(TestCase):
conn.sock = FakeSocket('')
conn.putrequest('GET', '/\x00')
def test_putrequest_override_host_validation(self):
class UnsafeHTTPConnection(client.HTTPConnection):
def _validate_host(self, url):
pass
conn = UnsafeHTTPConnection('example.com\r\n')
conn.sock = FakeSocket('')
# set skip_host so a ValueError is not raised upon adding the
# invalid URL as the value of the "Host:" header
conn.putrequest('GET', '/', skip_host=1)
def test_putrequest_override_encoding(self):
"""
It should be possible to override the default encoding

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@ -370,7 +370,7 @@ class urlopen_HttpTests(unittest.TestCase, FakeHTTPMixin, FakeFTPMixin):
self.unfakehttp()
@unittest.skipUnless(ssl, "ssl module required")
def test_url_with_control_char_rejected(self):
def test_url_path_with_control_char_rejected(self):
for char_no in list(range(0, 0x21)) + [0x7f]:
char = chr(char_no)
schemeless_url = f"//localhost:7777/test{char}/"
@ -397,7 +397,7 @@ class urlopen_HttpTests(unittest.TestCase, FakeHTTPMixin, FakeFTPMixin):
self.unfakehttp()
@unittest.skipUnless(ssl, "ssl module required")
def test_url_with_newline_header_injection_rejected(self):
def test_url_path_with_newline_header_injection_rejected(self):
self.fakehttp(b"HTTP/1.1 200 OK\r\n\r\nHello.")
host = "localhost:7777?a=1 HTTP/1.1\r\nX-injected: header\r\nTEST: 123"
schemeless_url = "//" + host + ":8080/test/?test=a"
@ -422,6 +422,38 @@ class urlopen_HttpTests(unittest.TestCase, FakeHTTPMixin, FakeFTPMixin):
finally:
self.unfakehttp()
@unittest.skipUnless(ssl, "ssl module required")
def test_url_host_with_control_char_rejected(self):
for char_no in list(range(0, 0x21)) + [0x7f]:
char = chr(char_no)
schemeless_url = f"//localhost{char}/test/"
self.fakehttp(b"HTTP/1.1 200 OK\r\n\r\nHello.")
try:
escaped_char_repr = repr(char).replace('\\', r'\\')
InvalidURL = http.client.InvalidURL
with self.assertRaisesRegex(
InvalidURL, f"contain control.*{escaped_char_repr}"):
urlopen(f"http:{schemeless_url}")
with self.assertRaisesRegex(InvalidURL, f"contain control.*{escaped_char_repr}"):
urlopen(f"https:{schemeless_url}")
finally:
self.unfakehttp()
@unittest.skipUnless(ssl, "ssl module required")
def test_url_host_with_newline_header_injection_rejected(self):
self.fakehttp(b"HTTP/1.1 200 OK\r\n\r\nHello.")
host = "localhost\r\nX-injected: header\r\n"
schemeless_url = "//" + host + ":8080/test/?test=a"
try:
InvalidURL = http.client.InvalidURL
with self.assertRaisesRegex(
InvalidURL, r"contain control.*\\r"):
urlopen(f"http:{schemeless_url}")
with self.assertRaisesRegex(InvalidURL, r"contain control.*\\n"):
urlopen(f"https:{schemeless_url}")
finally:
self.unfakehttp()
def test_read_0_9(self):
# "0.9" response accepted (but not "simple responses" without
# a status line)

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@ -0,0 +1 @@
Disallow control characters in hostnames in http.client, addressing CVE-2019-18348. Such potentially malicious header injection URLs now cause a InvalidURL to be raised.