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171 lines
8.0 KiB
171 lines
8.0 KiB
From 6c472d3a1d334d4eeb4a25eba7bf3b01611bf667 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: Thu, 6 May 2021 09:56:01 -0700
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Subject: [PATCH] [3.6] bpo-43882 - urllib.parse should sanitize urls
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containing ASCII newline and tabs (GH-25924)
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Co-authored-by: Gregory P. Smith <greg@krypto.org>
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Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>
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(cherry picked from commit 76cd81d60310d65d01f9d7b48a8985d8ab89c8b4)
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Co-authored-by: Senthil Kumaran <senthil@uthcode.com>
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(cherry picked from commit 515a7bc4e13645d0945b46a8e1d9102b918cd407)
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Co-authored-by: Miss Islington (bot) <31488909+miss-islington@users.noreply.github.com>
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---
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Doc/library/urllib.parse.rst | 13 +++++
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Lib/test/test_urlparse.py | 48 +++++++++++++++++++
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Lib/urllib/parse.py | 10 ++++
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.../2021-04-25-07-46-37.bpo-43882.Jpwx85.rst | 6 +++
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4 files changed, 77 insertions(+)
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create mode 100644 Misc/NEWS.d/next/Security/2021-04-25-07-46-37.bpo-43882.Jpwx85.rst
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diff --git a/Doc/library/urllib.parse.rst b/Doc/library/urllib.parse.rst
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index 3c2e37ef2093a..b717d7cc05b2e 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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@@ -288,6 +288,9 @@ 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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+
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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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returning :const:`None`.
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@@ -296,6 +299,10 @@ or on combining URL components into a URL string.
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Characters that affect netloc parsing under NFKC normalization will
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now raise :exc:`ValueError`.
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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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+
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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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@@ -633,6 +640,10 @@ task isn't already covered by the URL parsing functions above.
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.. seealso::
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+ `WHATWG`_ - URL Living standard
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+ Working Group for the URL Standard that defines URLs, domains, IP addresses, the
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+ application/x-www-form-urlencoded format, and their API.
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+
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:rfc:`3986` - Uniform Resource Identifiers
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This is the current standard (STD66). Any changes to urllib.parse module
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should conform to this. Certain deviations could be observed, which are
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@@ -656,3 +667,5 @@ task isn't already covered by the URL parsing functions above.
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:rfc:`1738` - Uniform Resource Locators (URL)
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This specifies the formal syntax and semantics of absolute URLs.
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+
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+.. _WHATWG: https://url.spec.whatwg.org/
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diff --git a/Lib/test/test_urlparse.py b/Lib/test/test_urlparse.py
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index e3088b2f39bd7..3509278a01694 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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@@ -612,6 +612,54 @@ def test_urlsplit_attributes(self):
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with self.assertRaisesRegex(ValueError, "out of range"):
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p.port
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+ def test_urlsplit_remove_unsafe_bytes(self):
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+ # Remove ASCII tabs and newlines from input, for http common case scenario.
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+ url = "h\nttp://www.python\n.org\t/java\nscript:\talert('msg\r\n')/?query\n=\tsomething#frag\nment"
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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, "www.python.org")
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+ self.assertEqual(p.path, "/javascript:alert('msg')/")
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+ self.assertEqual(p.query, "query=something")
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+ self.assertEqual(p.fragment, "fragment")
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+ self.assertEqual(p.username, None)
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+ self.assertEqual(p.password, None)
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+ self.assertEqual(p.hostname, "www.python.org")
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+ self.assertEqual(p.port, None)
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+ self.assertEqual(p.geturl(), "http://www.python.org/javascript:alert('msg')/?query=something#fragment")
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+
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+ # Remove ASCII tabs and newlines from input as bytes, for http common case scenario.
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+ url = b"h\nttp://www.python\n.org\t/java\nscript:\talert('msg\r\n')/?query\n=\tsomething#frag\nment"
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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"www.python.org")
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+ self.assertEqual(p.path, b"/javascript:alert('msg')/")
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+ self.assertEqual(p.query, b"query=something")
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+ self.assertEqual(p.fragment, b"fragment")
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+ self.assertEqual(p.username, None)
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+ self.assertEqual(p.password, None)
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+ self.assertEqual(p.hostname, b"www.python.org")
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+ self.assertEqual(p.port, None)
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+ self.assertEqual(p.geturl(), b"http://www.python.org/javascript:alert('msg')/?query=something#fragment")
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+
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+ # any scheme
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+ url = "x-new-scheme\t://www.python\n.org\t/java\nscript:\talert('msg\r\n')/?query\n=\tsomething#frag\nment"
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+ p = urllib.parse.urlsplit(url)
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+ self.assertEqual(p.geturl(), "x-new-scheme://www.python.org/javascript:alert('msg')/?query=something#fragment")
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+
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+ # Remove ASCII tabs and newlines from input as bytes, any scheme.
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+ url = b"x-new-scheme\t://www.python\n.org\t/java\nscript:\talert('msg\r\n')/?query\n=\tsomething#frag\nment"
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+ p = urllib.parse.urlsplit(url)
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+ self.assertEqual(p.geturl(), b"x-new-scheme://www.python.org/javascript:alert('msg')/?query=something#fragment")
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+
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+ # Unsafe bytes is not returned from urlparse cache.
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+ # scheme is stored after parsing, sending an scheme with unsafe bytes *will not* return an unsafe scheme
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+ url = "https://www.python\n.org\t/java\nscript:\talert('msg\r\n')/?query\n=\tsomething#frag\nment"
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+ scheme = "htt\nps"
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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/javascript:alert('msg')/?query=something#fragment")
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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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diff --git a/Lib/urllib/parse.py b/Lib/urllib/parse.py
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index 66056bf589bf6..ac6e7a9cee0b9 100644
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--- a/Lib/urllib/parse.py
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+++ b/Lib/urllib/parse.py
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@@ -76,6 +76,9 @@
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'0123456789'
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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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+
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# XXX: Consider replacing with functools.lru_cache
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MAX_CACHE_SIZE = 20
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_parse_cache = {}
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@@ -409,6 +412,11 @@ def _checknetloc(netloc):
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raise ValueError("netloc '" + netloc + "' contains invalid " +
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"characters under NFKC normalization")
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+def _remove_unsafe_bytes_from_url(url):
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+ for b in _UNSAFE_URL_BYTES_TO_REMOVE:
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+ url = url.replace(b, "")
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+ return url
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+
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def urlsplit(url, scheme='', allow_fragments=True):
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"""Parse a URL into 5 components:
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<scheme>://<netloc>/<path>?<query>#<fragment>
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@@ -416,6 +424,8 @@ def urlsplit(url, scheme='', allow_fragments=True):
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Note that we don't break the components up in smaller bits
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(e.g. netloc is a single string) and we don't expand % escapes."""
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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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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/2021-04-25-07-46-37.bpo-43882.Jpwx85.rst b/Misc/NEWS.d/next/Security/2021-04-25-07-46-37.bpo-43882.Jpwx85.rst
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new file mode 100644
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index 0000000000000..a326d079dff4a
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--- /dev/null
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+++ b/Misc/NEWS.d/next/Security/2021-04-25-07-46-37.bpo-43882.Jpwx85.rst
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@@ -0,0 +1,6 @@
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+The presence of newline or tab characters in parts of a URL could allow
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+some forms of attacks.
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+
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+Following the controlling specification for URLs defined by WHATWG
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+:func:`urllib.parse` now removes ASCII newlines and tabs from URLs,
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+preventing such attacks.
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