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224 lines
10 KiB
224 lines
10 KiB
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: "Miss Islington (bot)"
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<31488909+miss-islington@users.noreply.github.com>
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Date: Mon, 22 May 2023 03:42:37 -0700
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Subject: [PATCH] 00399: CVE-2023-24329
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gh-102153: Start stripping C0 control and space chars in `urlsplit` (GH-102508)
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`urllib.parse.urlsplit` has already been respecting the WHATWG spec a bit GH-25595.
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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).
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Backported from Python 3.12
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(cherry picked from commit f48a96a28012d28ae37a2f4587a780a5eb779946)
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Co-authored-by: Illia Volochii <illia.volochii@gmail.com>
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Co-authored-by: Gregory P. Smith [Google] <greg@krypto.org>
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---
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Doc/library/urllib.parse.rst | 40 +++++++++++-
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Lib/test/test_urlparse.py | 61 ++++++++++++++++++-
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Lib/urllib/parse.py | 12 ++++
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...-03-07-20-59-17.gh-issue-102153.14CLSZ.rst | 3 +
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4 files changed, 113 insertions(+), 3 deletions(-)
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create mode 100644 Misc/NEWS.d/next/Security/2023-03-07-20-59-17.gh-issue-102153.14CLSZ.rst
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diff --git a/Doc/library/urllib.parse.rst b/Doc/library/urllib.parse.rst
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index b717d7cc05..83a7a82089 100644
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--- a/Doc/library/urllib.parse.rst
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+++ b/Doc/library/urllib.parse.rst
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@@ -126,6 +126,12 @@ or on combining URL components into a URL string.
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``#``, ``@``, or ``:`` will raise a :exc:`ValueError`. If the URL is
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decomposed before parsing, no error will be raised.
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+
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+ .. warning::
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+
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+ :func:`urlparse` does not perform validation. See :ref:`URL parsing
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+ security <url-parsing-security>` for details.
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+
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.. versionchanged:: 3.2
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Added IPv6 URL parsing capabilities.
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@@ -288,8 +294,14 @@ or on combining URL components into a URL string.
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``#``, ``@``, or ``:`` will raise a :exc:`ValueError`. If the URL is
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decomposed before parsing, no error will be raised.
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- Following the `WHATWG spec`_ that updates RFC 3986, ASCII newline
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- ``\n``, ``\r`` and tab ``\t`` characters are stripped from the URL.
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+ Following some of the `WHATWG spec`_ that updates RFC 3986, leading C0
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+ control and space characters are stripped from the URL. ``\n``,
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+ ``\r`` and tab ``\t`` characters are removed from the URL at any position.
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+
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+ .. warning::
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+
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+ :func:`urlsplit` does not perform validation. See :ref:`URL parsing
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+ security <url-parsing-security>` for details.
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.. versionchanged:: 3.6
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Out-of-range port numbers now raise :exc:`ValueError`, instead of
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@@ -302,6 +314,9 @@ or on combining URL components into a URL string.
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.. versionchanged:: 3.6.14
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ASCII newline and tab characters are stripped from the URL.
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+ .. versionchanged:: 3.6.15
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+ Leading WHATWG C0 control and space characters are stripped from the URL.
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+
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.. _WHATWG spec: https://url.spec.whatwg.org/#concept-basic-url-parser
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.. function:: urlunsplit(parts)
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@@ -371,6 +386,27 @@ or on combining URL components into a URL string.
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.. versionchanged:: 3.2
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Result is a structured object rather than a simple 2-tuple.
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+.. _url-parsing-security:
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+
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+URL parsing security
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+--------------------
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+
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+The :func:`urlsplit` and :func:`urlparse` APIs do not perform **validation** of
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+inputs. They may not raise errors on inputs that other applications consider
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+invalid. They may also succeed on some inputs that might not be considered
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+URLs elsewhere. Their purpose is for practical functionality rather than
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+purity.
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+
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+Instead of raising an exception on unusual input, they may instead return some
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+component parts as empty strings. Or components may contain more than perhaps
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+they should.
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+
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+We recommend that users of these APIs where the values may be used anywhere
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+with security implications code defensively. Do some verification within your
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+code before trusting a returned component part. Does that ``scheme`` make
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+sense? Is that a sensible ``path``? Is there anything strange about that
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+``hostname``? etc.
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+
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.. _parsing-ascii-encoded-bytes:
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Parsing ASCII Encoded Bytes
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diff --git a/Lib/test/test_urlparse.py b/Lib/test/test_urlparse.py
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index 3509278a01..7fd61ffea9 100644
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--- a/Lib/test/test_urlparse.py
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+++ b/Lib/test/test_urlparse.py
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@@ -660,6 +660,65 @@ class UrlParseTestCase(unittest.TestCase):
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self.assertEqual(p.scheme, "https")
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self.assertEqual(p.geturl(), "https://www.python.org/javascript:alert('msg')/?query=something#fragment")
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+ def test_urlsplit_strip_url(self):
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+ noise = bytes(range(0, 0x20 + 1))
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+ base_url = "http://User:Pass@www.python.org:080/doc/?query=yes#frag"
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+
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+ url = noise.decode("utf-8") + base_url
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+ p = urllib.parse.urlsplit(url)
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+ self.assertEqual(p.scheme, "http")
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+ self.assertEqual(p.netloc, "User:Pass@www.python.org:080")
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+ self.assertEqual(p.path, "/doc/")
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+ self.assertEqual(p.query, "query=yes")
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+ self.assertEqual(p.fragment, "frag")
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+ self.assertEqual(p.username, "User")
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+ self.assertEqual(p.password, "Pass")
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+ self.assertEqual(p.hostname, "www.python.org")
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+ self.assertEqual(p.port, 80)
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+ self.assertEqual(p.geturl(), base_url)
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+
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+ url = noise + base_url.encode("utf-8")
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+ p = urllib.parse.urlsplit(url)
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+ self.assertEqual(p.scheme, b"http")
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+ self.assertEqual(p.netloc, b"User:Pass@www.python.org:080")
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+ self.assertEqual(p.path, b"/doc/")
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+ self.assertEqual(p.query, b"query=yes")
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+ self.assertEqual(p.fragment, b"frag")
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+ self.assertEqual(p.username, b"User")
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+ self.assertEqual(p.password, b"Pass")
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+ self.assertEqual(p.hostname, b"www.python.org")
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+ self.assertEqual(p.port, 80)
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+ self.assertEqual(p.geturl(), base_url.encode("utf-8"))
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+
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+ # Test that trailing space is preserved as some applications rely on
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+ # this within query strings.
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+ query_spaces_url = "https://www.python.org:88/doc/?query= "
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+ p = urllib.parse.urlsplit(noise.decode("utf-8") + query_spaces_url)
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+ self.assertEqual(p.scheme, "https")
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+ self.assertEqual(p.netloc, "www.python.org:88")
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+ self.assertEqual(p.path, "/doc/")
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+ self.assertEqual(p.query, "query= ")
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+ self.assertEqual(p.port, 88)
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+ self.assertEqual(p.geturl(), query_spaces_url)
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+
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+ p = urllib.parse.urlsplit("www.pypi.org ")
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+ # That "hostname" gets considered a "path" due to the
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+ # trailing space and our existing logic... YUCK...
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+ # and re-assembles via geturl aka unurlsplit into the original.
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+ # django.core.validators.URLValidator (at least through v3.2) relies on
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+ # this, for better or worse, to catch it in a ValidationError via its
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+ # regular expressions.
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+ # Here we test the basic round trip concept of such a trailing space.
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+ self.assertEqual(urllib.parse.urlunsplit(p), "www.pypi.org ")
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+
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+ # with scheme as cache-key
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+ url = "//www.python.org/"
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+ scheme = noise.decode("utf-8") + "https" + noise.decode("utf-8")
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+ for _ in range(2):
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+ p = urllib.parse.urlsplit(url, scheme=scheme)
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+ self.assertEqual(p.scheme, "https")
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+ self.assertEqual(p.geturl(), "https://www.python.org/")
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+
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def test_attributes_bad_port(self):
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"""Check handling of invalid ports."""
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for bytes in (False, True):
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@@ -667,7 +726,7 @@ class UrlParseTestCase(unittest.TestCase):
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for port in ("foo", "1.5", "-1", "0x10"):
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with self.subTest(bytes=bytes, parse=parse, port=port):
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netloc = "www.example.net:" + port
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- url = "http://" + netloc
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+ url = "http://" + netloc + "/"
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if bytes:
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netloc = netloc.encode("ascii")
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url = url.encode("ascii")
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diff --git a/Lib/urllib/parse.py b/Lib/urllib/parse.py
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index ac6e7a9cee..717e990997 100644
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--- a/Lib/urllib/parse.py
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+++ b/Lib/urllib/parse.py
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@@ -25,6 +25,10 @@ currently not entirely compliant with this RFC due to defacto
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scenarios for parsing, and for backward compatibility purposes, some
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parsing quirks from older RFCs are retained. The testcases in
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test_urlparse.py provides a good indicator of parsing behavior.
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+
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+The WHATWG URL Parser spec should also be considered. We are not compliant with
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+it either due to existing user code API behavior expectations (Hyrum's Law).
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+It serves as a useful guide when making changes.
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"""
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import re
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@@ -76,6 +80,10 @@ scheme_chars = ('abcdefghijklmnopqrstuvwxyz'
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'0123456789'
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'+-.')
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+# Leading and trailing C0 control and space to be stripped per WHATWG spec.
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+# == "".join([chr(i) for i in range(0, 0x20 + 1)])
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+_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 '
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+
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# Unsafe bytes to be removed per WHATWG spec
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_UNSAFE_URL_BYTES_TO_REMOVE = ['\t', '\r', '\n']
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@@ -426,6 +434,10 @@ def urlsplit(url, scheme='', allow_fragments=True):
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url, scheme, _coerce_result = _coerce_args(url, scheme)
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url = _remove_unsafe_bytes_from_url(url)
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scheme = _remove_unsafe_bytes_from_url(scheme)
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+ # Only lstrip url as some applications rely on preserving trailing space.
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+ # (https://url.spec.whatwg.org/#concept-basic-url-parser would strip both)
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+ url = url.lstrip(_WHATWG_C0_CONTROL_OR_SPACE)
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+ scheme = scheme.strip(_WHATWG_C0_CONTROL_OR_SPACE)
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allow_fragments = bool(allow_fragments)
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key = url, scheme, allow_fragments, type(url), type(scheme)
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cached = _parse_cache.get(key, None)
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diff --git a/Misc/NEWS.d/next/Security/2023-03-07-20-59-17.gh-issue-102153.14CLSZ.rst b/Misc/NEWS.d/next/Security/2023-03-07-20-59-17.gh-issue-102153.14CLSZ.rst
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new file mode 100644
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index 0000000000..e57ac4ed3a
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--- /dev/null
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+++ b/Misc/NEWS.d/next/Security/2023-03-07-20-59-17.gh-issue-102153.14CLSZ.rst
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@@ -0,0 +1,3 @@
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+:func:`urllib.parse.urlsplit` now strips leading C0 control and space
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+characters following the specification for URLs defined by WHATWG in
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+response to CVE-2023-24329. Patch by Illia Volochii.
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