00399-cve-2023-24329.patch

00399 #

* pythongh-102153: Start stripping C0 control and space chars in `urlsplit` (pythonGH-102508)

`urllib.parse.urlsplit` has already been respecting the WHATWG spec a bit pythonGH-25595.

This adds more sanitizing to respect the "Remove any leading C0 control or space from input" [rule](https://url.spec.whatwg.org/GH-url-parsing:~:text=Remove%20any%20leading%20and%20trailing%20C0%20control%20or%20space%20from%20input.) in response to [CVE-2023-24329](https://nvd.nist.gov/vuln/detail/CVE-2023-24329).

Backported to Python 2 from Python 3.12.

Co-authored-by: Illia Volochii <illia.volochii@gmail.com>
Co-authored-by: Gregory P. Smith [Google] <greg@krypto.org>
Co-authored-by: Lumir Balhar <lbalhar@redhat.com>

Lib/test/test_urlparse.py

@@ -666,7 +666,64 @@ def test_urlsplit_remove_unsafe_bytes(self):
             self.assertEqual(p.scheme, "https")
             self.assertEqual(p.geturl(), "https://www.python.org/javascript:alert('msg')/?query=something#fragment")
 
+    def test_urlsplit_strip_url(self):
+        noise = "".join([chr(i) for i in range(0, 0x20 + 1)])
+        base_url = "http://User:Pass@www.python.org:080/doc/?query=yes#frag"
 
+        url = noise.decode("utf-8") + base_url
+        p = urlparse.urlsplit(url)
+        self.assertEqual(p.scheme, "http")
+        self.assertEqual(p.netloc, "User:Pass@www.python.org:080")
+        self.assertEqual(p.path, "/doc/")
+        self.assertEqual(p.query, "query=yes")
+        self.assertEqual(p.fragment, "frag")
+        self.assertEqual(p.username, "User")
+        self.assertEqual(p.password, "Pass")
+        self.assertEqual(p.hostname, "www.python.org")
+        self.assertEqual(p.port, 80)
+        self.assertEqual(p.geturl(), base_url)
+
+        url = noise + base_url.encode("utf-8")
+        p = urlparse.urlsplit(url)
+        self.assertEqual(p.scheme, b"http")
+        self.assertEqual(p.netloc, b"User:Pass@www.python.org:080")
+        self.assertEqual(p.path, b"/doc/")
+        self.assertEqual(p.query, b"query=yes")
+        self.assertEqual(p.fragment, b"frag")
+        self.assertEqual(p.username, b"User")
+        self.assertEqual(p.password, b"Pass")
+        self.assertEqual(p.hostname, b"www.python.org")
+        self.assertEqual(p.port, 80)
+        self.assertEqual(p.geturl(), base_url.encode("utf-8"))
+
+        # Test that trailing space is preserved as some applications rely on
+        # this within query strings.
+        query_spaces_url = "https://www.python.org:88/doc/?query=    "
+        p = urlparse.urlsplit(noise.decode("utf-8") + query_spaces_url)
+        self.assertEqual(p.scheme, "https")
+        self.assertEqual(p.netloc, "www.python.org:88")
+        self.assertEqual(p.path, "/doc/")
+        self.assertEqual(p.query, "query=    ")
+        self.assertEqual(p.port, 88)
+        self.assertEqual(p.geturl(), query_spaces_url)
+
+        p = urlparse.urlsplit("www.pypi.org ")
+        # That "hostname" gets considered a "path" due to the
+        # trailing space and our existing logic...  YUCK...
+        # and re-assembles via geturl aka unurlsplit into the original.
+        # django.core.validators.URLValidator (at least through v3.2) relies on
+        # this, for better or worse, to catch it in a ValidationError via its
+        # regular expressions.
+        # Here we test the basic round trip concept of such a trailing space.
+        self.assertEqual(urlparse.urlunsplit(p), "www.pypi.org ")
+
+        # with scheme as cache-key
+        url = "//www.python.org/"
+        scheme = noise.decode("utf-8") + "https" + noise.decode("utf-8")
+        for _ in range(2):
+            p = urlparse.urlsplit(url, scheme=scheme)
+            self.assertEqual(p.scheme, "https")
+            self.assertEqual(p.geturl(), "https://www.python.org/")
 
     def test_attributes_bad_port(self):
         """Check handling of non-integer ports."""

Lib/urlparse.py

@@ -26,6 +26,10 @@
 parsing quirks from older RFCs are retained. The testcases in
 test_urlparse.py provides a good indicator of parsing behavior.
 
+The WHATWG URL Parser spec should also be considered.  We are not compliant with
+it either due to existing user code API behavior expectations (Hyrum's Law).
+It serves as a useful guide when making changes.
+
 """
 
 import re
@@ -63,6 +67,10 @@
                 '0123456789'
                 '+-.')
 
+# Leading and trailing C0 control and space to be stripped per WHATWG spec.
+# == "".join([chr(i) for i in range(0, 0x20 + 1)])
+_WHATWG_C0_CONTROL_OR_SPACE = '\x00\x01\x02\x03\x04\x05\x06\x07\x08\t\n\x0b\x0c\r\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f '
+
 # Unsafe bytes to be removed per WHATWG spec
 _UNSAFE_URL_BYTES_TO_REMOVE = ['\t', '\r', '\n']
 
@@ -201,6 +209,8 @@ def urlsplit(url, scheme='', allow_fragments=True):
     (e.g. netloc is a single string) and we don't expand % escapes."""
     url = _remove_unsafe_bytes_from_url(url)
     scheme = _remove_unsafe_bytes_from_url(scheme)
+    url = url.lstrip(_WHATWG_C0_CONTROL_OR_SPACE)
+    scheme = scheme.strip(_WHATWG_C0_CONTROL_OR_SPACE)
     allow_fragments = bool(allow_fragments)
     key = url, scheme, allow_fragments, type(url), type(scheme)
     cached = _parse_cache.get(key, None)