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python-doc.33823
CVE-2021-23336-only-amp-as-query-sep.patch
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File CVE-2021-23336-only-amp-as-query-sep.patch of Package python-doc.33823
From 5c17dfc5d70ce88be99bc5769b91ce79d7a90d61 Mon Sep 17 00:00:00 2001 From: Senthil Kumaran <senthil@uthcode.com> Date: Mon, 15 Feb 2021 11:16:43 -0800 Subject: [PATCH] [3.6] bpo-42967: only use '&' as a query string separator (GH-24297) (GH-24532) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit bpo-42967: [security] Address a web cache-poisoning issue reported in urllib.parse.parse_qsl(). urllib.parse will only us "&" as query string separator by default instead of both ";" and "&" as allowed in earlier versions. An optional argument seperator with default value "&" is added to specify the separator. Co-authored-by: Éric Araujo <merwok@netwok.org> Co-authored-by: Ken Jin <28750310+Fidget-Spinner@users.noreply.github.com> Co-authored-by: Adam Goldschmidt <adamgold7@gmail.com> --- Doc/library/cgi.rst | 8 ++- Doc/library/urllib.parse.rst | 22 +++++- Doc/whatsnew/3.6.rst | 13 ++++ Lib/cgi.py | 17 +++-- Lib/test/test_cgi.py | 29 ++++++-- Lib/test/test_urlparse.py | 68 +++++++++++++------ Lib/urllib/parse.py | 19 ++++-- .../2021-02-14-15-59-16.bpo-42967.YApqDS.rst | 1 + 8 files changed, 134 insertions(+), 43 deletions(-) create mode 100644 Misc/NEWS.d/next/Security/2021-02-14-15-59-16.bpo-42967.YApqDS.rst --- a/Doc/library/cgi.rst +++ b/Doc/library/cgi.rst @@ -287,10 +287,11 @@ algorithms implemented in this module in .. function:: parse(fp[, environ[, keep_blank_values[, strict_parsing]]]) - Parse a query in the environment or from a file (the file defaults to - ``sys.stdin`` and environment defaults to ``os.environ``). The *keep_blank_values* and *strict_parsing* parameters are - passed to :func:`urlparse.parse_qs` unchanged. - + Parse a query in the environment or from a file (the file + defaults to ``sys.stdin`` and environment defaults to + ``os.environ``). The *keep_blank_values*, *strict_parsing*, + and *separator* parameters are passed to + :func:`urlparse.parse_qs` unchanged. .. function:: parse_qs(qs[, keep_blank_values[, strict_parsing[, max_num_fields]]]) @@ -316,6 +317,9 @@ algorithms implemented in this module in Note that this does not parse nested multipart parts --- use :class:`FieldStorage` for that. + .. versionchanged:: 3.6.13 + Added the *separator* parameter. + .. function:: parse_header(string) --- a/Lib/cgi.py +++ b/Lib/cgi.py @@ -121,7 +121,8 @@ log = initlog # The current lo # 0 ==> unlimited input maxlen = 0 -def parse(fp=None, environ=os.environ, keep_blank_values=0, strict_parsing=0): +def parse(fp=None, environ=os.environ, keep_blank_values=0, + strict_parsing=0, separator='&'): """Parse a query in the environment or from a file (default stdin) Arguments, all optional: @@ -140,6 +141,9 @@ def parse(fp=None, environ=os.environ, k strict_parsing: flag indicating what to do with parsing errors. If false (the default), errors are silently ignored. If true, errors raise a ValueError exception. + + separator: str. The symbol to use for separating the query arguments. + Defaults to &. """ if fp is None: fp = sys.stdin @@ -171,7 +175,8 @@ def parse(fp=None, environ=os.environ, k else: qs = "" environ['QUERY_STRING'] = qs # XXX Shouldn't, really - return urlparse.parse_qs(qs, keep_blank_values, strict_parsing) + return urlparse.parse_qs(qs, keep_blank_values, strict_parsing, + separator=separator) # parse query string function called from urlparse, @@ -395,7 +400,7 @@ class FieldStorage: def __init__(self, fp=None, headers=None, outerboundary="", environ=os.environ, keep_blank_values=0, strict_parsing=0, - max_num_fields=None): + max_num_fields=None, separator='&'): """Constructor. Read multipart/* until last part. Arguments, all optional: @@ -430,6 +435,7 @@ class FieldStorage: self.keep_blank_values = keep_blank_values self.strict_parsing = strict_parsing self.max_num_fields = max_num_fields + self.separator = separator if 'REQUEST_METHOD' in environ: method = environ['REQUEST_METHOD'].upper() self.qs_on_post = None @@ -613,7 +619,9 @@ class FieldStorage: if self.qs_on_post: qs += '&' + self.qs_on_post query = urlparse.parse_qsl(qs, self.keep_blank_values, - self.strict_parsing, self.max_num_fields) + self.strict_parsing, + self.max_num_fields, + separator=self.separator) self.list = [MiniFieldStorage(key, value) for key, value in query] self.skip_lines() @@ -629,7 +637,8 @@ class FieldStorage: query = urlparse.parse_qsl(self.qs_on_post, self.keep_blank_values, self.strict_parsing, - self.max_num_fields) + self.max_num_fields, + self.separator) self.list.extend(MiniFieldStorage(key, value) for key, value in query) FieldStorageClass = None @@ -642,7 +651,8 @@ class FieldStorage: klass = self.FieldStorageClass or self.__class__ part = klass(self.fp, {}, ib, environ, keep_blank_values, strict_parsing, - max_num_fields) + max_num_fields, + self.separator) # Throw first part away while not part.done: --- a/Lib/test/test_cgi.py +++ b/Lib/test/test_cgi.py @@ -61,12 +61,9 @@ parse_strict_test_cases = [ ("", ValueError("bad query field: ''")), ("&", ValueError("bad query field: ''")), ("&&", ValueError("bad query field: ''")), - (";", ValueError("bad query field: ''")), - (";&;", ValueError("bad query field: ''")), # Should the next few really be valid? ("=", {}), ("=&=", {}), - ("=;=", {}), # This rest seem to make sense ("=a", {'': ['a']}), ("&=a", ValueError("bad query field: ''")), @@ -81,8 +78,6 @@ parse_strict_test_cases = [ ("a=a+b&b=b+c", {'a': ['a b'], 'b': ['b c']}), ("a=a+b&a=b+a", {'a': ['a b', 'b a']}), ("x=1&y=2.0&z=2-3.%2b0", {'x': ['1'], 'y': ['2.0'], 'z': ['2-3.+0']}), - ("x=1;y=2.0&z=2-3.%2b0", {'x': ['1'], 'y': ['2.0'], 'z': ['2-3.+0']}), - ("x=1;y=2.0;z=2-3.%2b0", {'x': ['1'], 'y': ['2.0'], 'z': ['2-3.+0']}), ("Hbc5161168c542333633315dee1182227:key_store_seqid=400006&cuyer=r&view=bustomer&order_id=0bb2e248638833d48cb7fed300000f1b&expire=964546263&lobale=en-US&kid=130003.300038&ss=env", {'Hbc5161168c542333633315dee1182227:key_store_seqid': ['400006'], 'cuyer': ['r'], @@ -188,6 +183,30 @@ class CgiTests(unittest.TestCase): self.assertEqual(expect[k], v) self.assertItemsEqual(expect.values(), d.values()) + def test_separator(self): + parse_semicolon = [ + ("x=1;y=2.0", {'x': ['1'], 'y': ['2.0']}), + ("x=1;y=2.0;z=2-3.%2b0", {'x': ['1'], 'y': ['2.0'], 'z': ['2-3.+0']}), + (";", ValueError("bad query field: ''")), + (";;", ValueError("bad query field: ''")), + ("=;a", ValueError("bad query field: 'a'")), + (";b=a", ValueError("bad query field: ''")), + ("b;=a", ValueError("bad query field: 'b'")), + ("a=a+b;b=b+c", {'a': ['a b'], 'b': ['b c']}), + ("a=a+b;a=b+a", {'a': ['a b', 'b a']}), + ] + for orig, expect in parse_semicolon: + env = {'QUERY_STRING': orig} + fs = cgi.FieldStorage(separator=';', environ=env) + if isinstance(expect, dict): + for key in expect.keys(): + expect_val = expect[key] + self.assertIn(key, fs) + if len(expect_val) > 1: + self.assertEqual(fs.getvalue(key), expect_val) + else: + self.assertEqual(fs.getvalue(key), expect_val[0]) + def test_log(self): cgi.log("Testing") --- a/Lib/test/test_urlparse.py +++ b/Lib/test/test_urlparse.py @@ -24,16 +24,10 @@ parse_qsl_test_cases = [ ("&a=b", [('a', 'b')]), ("a=a+b&b=b+c", [('a', 'a b'), ('b', 'b c')]), ("a=1&a=2", [('a', '1'), ('a', '2')]), - (";", []), - (";;", []), - (";a=b", [('a', 'b')]), - ("a=a+b;b=b+c", [('a', 'a b'), ('b', 'b c')]), - ("a=1;a=2", [('a', '1'), ('a', '2')]), - (b";", []), - (b";;", []), - (b";a=b", [(b'a', b'b')]), - (b"a=a+b;b=b+c", [(b'a', b'a b'), (b'b', b'b c')]), - (b"a=1;a=2", [(b'a', b'1'), (b'a', b'2')]), + (";a=b", [(';a', 'b')]), + ("a=a+b;b=b+c", [('a', 'a b;b=b c')]), + (b";a=b", [(b';a', b'b')]), + (b"a=a+b;b=b+c", [(b'a', b'a b;b=b c')]), ] parse_qs_test_cases = [ @@ -57,16 +51,10 @@ parse_qs_test_cases = [ (b"&a=b", {b'a': [b'b']}), (b"a=a+b&b=b+c", {b'a': [b'a b'], b'b': [b'b c']}), (b"a=1&a=2", {b'a': [b'1', b'2']}), - (";", {}), - (";;", {}), - (";a=b", {'a': ['b']}), - ("a=a+b;b=b+c", {'a': ['a b'], 'b': ['b c']}), - ("a=1;a=2", {'a': ['1', '2']}), - (b";", {}), - (b";;", {}), - (b";a=b", {b'a': [b'b']}), - (b"a=a+b;b=b+c", {b'a': [b'a b'], b'b': [b'b c']}), - (b"a=1;a=2", {b'a': [b'1', b'2']}), + (";a=b", {';a': ['b']}), + ("a=a+b;b=b+c", {'a': ['a b;b=b c']}), + (b";a=b", {b';a': [b'b']}), + (b"a=a+b;b=b+c", {b'a':[ b'a b;b=b c']}), ] class UrlParseTestCase(unittest.TestCase): @@ -665,6 +653,43 @@ class UrlParseTestCase(unittest.TestCase "under NFKC normalization") self.assertIsInstance(cm.exception.args[0], str) + def test_parse_qs_separator(self): + parse_qs_semicolon_cases = [ + (";", {}), + (";;", {}), + (";a=b", {'a': ['b']}), + ("a=a+b;b=b+c", {'a': ['a b'], 'b': ['b c']}), + ("a=1;a=2", {'a': ['1', '2']}), + (b";", {}), + (b";;", {}), + (b";a=b", {b'a': [b'b']}), + (b"a=a+b;b=b+c", {b'a': [b'a b'], b'b': [b'b c']}), + (b"a=1;a=2", {b'a': [b'1', b'2']}), + ] + for orig, expect in parse_qs_semicolon_cases: + result = urlparse.parse_qs(orig, separator=';') + self.assertEqual(result, expect, "Error parsing %r" % orig) + + + def test_parse_qsl_separator(self): + parse_qsl_semicolon_cases = [ + (";", []), + (";;", []), + (";a=b", [('a', 'b')]), + ("a=a+b;b=b+c", [('a', 'a b'), ('b', 'b c')]), + ("a=1;a=2", [('a', '1'), ('a', '2')]), + (b";", []), + (b";;", []), + (b";a=b", [(b'a', b'b')]), + (b"a=a+b;b=b+c", [(b'a', b'a b'), (b'b', b'b c')]), + (b"a=1;a=2", [(b'a', b'1'), (b'a', b'2')]), + ] + for orig, expect in parse_qsl_semicolon_cases: + result = urlparse.parse_qsl(orig, separator=';') + self.assertEqual(result, expect, "Error parsing %r" % orig) + + + def test_main(): test_support.run_unittest(UrlParseTestCase) --- /dev/null +++ b/Misc/NEWS.d/next/Security/2021-02-14-15-59-16.bpo-42967.YApqDS.rst @@ -0,0 +1 @@ +Fix web cache poisoning vulnerability by defaulting the query args separator to ``&``, and allowing the user to choose a custom separator. --- a/Lib/test/test_urllib2.py +++ b/Lib/test/test_urllib2.py @@ -1331,7 +1331,7 @@ class MiscTests(unittest.TestCase, FakeH # level 'def urlopen()' function defined in this... (quite ugly) # test suite. They use different url opening codepaths. Plain # urlopen uses FancyURLOpener which goes via a codepath that - # calls urllib.parse.quote() on the URL which makes all of the + # calls urlparse.quote() on the URL which makes all of the # above attempts at injection within the url _path_ safe. escaped_char_repr = repr(char).replace('\\', r'\\') InvalidURL = httplib.InvalidURL @@ -1354,7 +1354,7 @@ class MiscTests(unittest.TestCase, FakeH # level 'def urlopen()' function defined in this... (quite ugly) # test suite. They use different url opening codepaths. Plain # urlopen uses FancyURLOpener which goes via a codepath that - # calls urllib.parse.quote() on the URL which makes all of the + # calls urlparse.quote() on the URL which makes all of the # above attempts at injection within the url _path_ safe. InvalidURL = httplib.InvalidURL with self.assertRaisesRegexp(InvalidURL, --- a/Misc/NEWS +++ b/Misc/NEWS @@ -4246,7 +4246,7 @@ Library - bpo-18167: cgi.FieldStorage no longer fails to handle multipart/form-data when \r\n appears at end of 65535 bytes without other newlines. -- bpo-17403: urllib.parse.robotparser normalizes the urls before adding to +- bpo-17403: urlparse.robotparser normalizes the urls before adding to ruleline. This helps in handling certain types invalid urls in a conservative manner. Patch contributed by Mher Movsisyan. @@ -8271,7 +8271,7 @@ Core and Builtins Library ------- -- bpo-7904: Changes to urllib.parse.urlsplit to handle schemes as defined by +- bpo-7904: Changes to urlparse.urlsplit to handle schemes as defined by RFC3986. Anything before :// is considered a scheme and is followed by an authority (or netloc) and by '/' led path, which is optional. --- a/Lib/urlparse.py +++ b/Lib/urlparse.py @@ -382,7 +382,8 @@ def unquote(s): append(item) return ''.join(res) -def parse_qs(qs, keep_blank_values=0, strict_parsing=0, max_num_fields=None): +def parse_qs(qs, keep_blank_values=0, strict_parsing=0, + max_num_fields=None, separator='&'): """Parse a query given as a string argument. Arguments: @@ -402,17 +403,21 @@ def parse_qs(qs, keep_blank_values=0, st max_num_fields: int. If set, then throws a ValueError if there are more than n fields read by parse_qsl(). + + separator: str. The symbol to use for separating the query arguments. + Defaults to &. """ dict = {} for name, value in parse_qsl(qs, keep_blank_values, strict_parsing, - max_num_fields): + max_num_fields, separator=separator): if name in dict: dict[name].append(value) else: dict[name] = [value] return dict -def parse_qsl(qs, keep_blank_values=0, strict_parsing=0, max_num_fields=None): +def parse_qsl(qs, keep_blank_values=0, strict_parsing=0, + max_num_fields=None, separator='&'): """Parse a query given as a string argument. Arguments: @@ -432,17 +437,23 @@ def parse_qsl(qs, keep_blank_values=0, s max_num_fields: int. If set, then throws a ValueError if there are more than n fields read by parse_qsl(). + separator: str. The symbol to use for separating the query arguments. + Defaults to &. + Returns a list, as G-d intended. """ # If max_num_fields is defined then check that the number of fields # is less than max_num_fields. This prevents a memory exhaustion DOS # attack via post bodies with many fields. + if not separator or (not isinstance(separator, (str, bytes))): + raise ValueError("Separator must be of type string or bytes.") + if max_num_fields is not None: - num_fields = 1 + qs.count('&') + qs.count(';') + num_fields = 1 + qs.count(separator) if max_num_fields < num_fields: raise ValueError('Max number of fields exceeded') - pairs = [s2 for s1 in qs.split('&') for s2 in s1.split(';')] + pairs = [s1 for s1 in qs.split(separator)] r = [] for name_value in pairs: if not name_value and not strict_parsing:
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