From 3e3669c9c41a27e1466e2c28b3906e3dd0ce3e7e Mon Sep 17 00:00:00 2001 From: Steve Dower Date: Thu, 7 Mar 2019 08:25:22 -0800 Subject: [PATCH] bpo-36216: Add check for characters in netloc that normalize to separators (GH-12201) CVE: CVE-2019-9636 Upstream-Status: Backport https://github.com/python/cpython/pull/12216/commits/3e3669c9c41a27e1466e2c28b3906e3dd0ce3e7e Signed-off-by: Martin Jansa --- Doc/library/urlparse.rst | 20 ++++++++++++++++ Lib/test/test_urlparse.py | 24 +++++++++++++++++++ Lib/urlparse.py | 17 +++++++++++++ .../2019-03-06-09-38-40.bpo-36216.6q1m4a.rst | 3 +++ 4 files changed, 64 insertions(+) create mode 100644 Misc/NEWS.d/next/Security/2019-03-06-09-38-40.bpo-36216.6q1m4a.rst diff --git a/Lib/test/test_urlparse.py b/Lib/test/test_urlparse.py index 4e1ded73c266..73b0228ea8e3 100644 --- a/Lib/test/test_urlparse.py +++ b/Lib/test/test_urlparse.py @@ -1,4 +1,6 @@ from test import test_support +import sys +import unicodedata import unittest import urlparse @@ -624,6 +626,28 @@ def test_portseparator(self): self.assertEqual(urlparse.urlparse("http://www.python.org:80"), ('http','www.python.org:80','','','','')) + def test_urlsplit_normalization(self): + # Certain characters should never occur in the netloc, + # including under normalization. + # Ensure that ALL of them are detected and cause an error + illegal_chars = u'/:#?@' + hex_chars = {'{:04X}'.format(ord(c)) for c in illegal_chars} + denorm_chars = [ + c for c in map(unichr, range(128, sys.maxunicode)) + if (hex_chars & set(unicodedata.decomposition(c).split())) + and c not in illegal_chars + ] + # Sanity check that we found at least one such character + self.assertIn(u'\u2100', denorm_chars) + self.assertIn(u'\uFF03', denorm_chars) + + for scheme in [u"http", u"https", u"ftp"]: + for c in denorm_chars: + url = u"{}://netloc{}false.netloc/path".format(scheme, c) + print "Checking %r" % url + with self.assertRaises(ValueError): + urlparse.urlsplit(url) + def test_main(): test_support.run_unittest(UrlParseTestCase) diff --git a/Lib/urlparse.py b/Lib/urlparse.py index f7c2b032b097..54eda08651ab 100644 --- a/Lib/urlparse.py +++ b/Lib/urlparse.py @@ -165,6 +165,21 @@ def _splitnetloc(url, start=0): delim = min(delim, wdelim) # use earliest delim position return url[start:delim], url[delim:] # return (domain, rest) +def _checknetloc(netloc): + if not netloc or not isinstance(netloc, unicode): + return + # looking for characters like \u2100 that expand to 'a/c' + # IDNA uses NFKC equivalence, so normalize for this check + import unicodedata + netloc2 = unicodedata.normalize('NFKC', netloc) + if netloc == netloc2: + return + _, _, netloc = netloc.rpartition('@') # anything to the left of '@' is okay + for c in '/?#@:': + if c in netloc2: + raise ValueError("netloc '" + netloc2 + "' contains invalid " + + "characters under NFKC normalization") + def urlsplit(url, scheme='', allow_fragments=True): """Parse a URL into 5 components: :///?# @@ -193,6 +208,7 @@ def urlsplit(url, scheme='', allow_fragments=True): url, fragment = url.split('#', 1) if '?' in url: url, query = url.split('?', 1) + _checknetloc(netloc) v = SplitResult(scheme, netloc, url, query, fragment) _parse_cache[key] = v return v @@ -216,6 +232,7 @@ def urlsplit(url, scheme='', allow_fragments=True): url, fragment = url.split('#', 1) if '?' in url: url, query = url.split('?', 1) + _checknetloc(netloc) v = SplitResult(scheme, netloc, url, query, fragment) _parse_cache[key] = v return v diff --git a/Misc/NEWS.d/next/Security/2019-03-06-09-38-40.bpo-36216.6q1m4a.rst b/Misc/NEWS.d/next/Security/2019-03-06-09-38-40.bpo-36216.6q1m4a.rst new file mode 100644 index 000000000000..1e1ad92c6feb --- /dev/null +++ b/Misc/NEWS.d/next/Security/2019-03-06-09-38-40.bpo-36216.6q1m4a.rst @@ -0,0 +1,3 @@ +Changes urlsplit() to raise ValueError when the URL contains characters that +decompose under IDNA encoding (NFKC-normalization) into characters that +affect how the URL is parsed. \ No newline at end of file