From 7cf314f3eb83750ec70f5b86045a5f5d195cddef Mon Sep 17 00:00:00 2001 From: Trevor Gamblin Date: Thu, 23 Apr 2020 07:04:36 -0700 Subject: python3: fix CVE-2020-8492 CVE: CVE-2020-8492 Signed-off-by: Trevor Gamblin Signed-off-by: Richard Purdie --- ...VE-2020-8492-Fix-AbstractBasicAuthHandler.patch | 248 +++++++++++++++++++++ meta/recipes-devtools/python/python3_3.8.2.bb | 1 + 2 files changed, 249 insertions(+) create mode 100644 meta/recipes-devtools/python/files/0001-bpo-39503-CVE-2020-8492-Fix-AbstractBasicAuthHandler.patch diff --git a/meta/recipes-devtools/python/files/0001-bpo-39503-CVE-2020-8492-Fix-AbstractBasicAuthHandler.patch b/meta/recipes-devtools/python/files/0001-bpo-39503-CVE-2020-8492-Fix-AbstractBasicAuthHandler.patch new file mode 100644 index 0000000000..e16b99bcb9 --- /dev/null +++ b/meta/recipes-devtools/python/files/0001-bpo-39503-CVE-2020-8492-Fix-AbstractBasicAuthHandler.patch @@ -0,0 +1,248 @@ +From 0b297d4ff1c0e4480ad33acae793fbaf4bf015b4 Mon Sep 17 00:00:00 2001 +From: Victor Stinner +Date: Thu, 2 Apr 2020 02:52:20 +0200 +Subject: [PATCH] bpo-39503: CVE-2020-8492: Fix AbstractBasicAuthHandler + (GH-18284) + +Upstream-Status: Backport +(https://github.com/python/cpython/commit/0b297d4ff1c0e4480ad33acae793fbaf4bf015b4) + +CVE: CVE-2020-8492 + +The AbstractBasicAuthHandler class of the urllib.request module uses +an inefficient regular expression which can be exploited by an +attacker to cause a denial of service. Fix the regex to prevent the +catastrophic backtracking. Vulnerability reported by Ben Caller +and Matt Schwager. + +AbstractBasicAuthHandler of urllib.request now parses all +WWW-Authenticate HTTP headers and accepts multiple challenges per +header: use the realm of the first Basic challenge. + +Co-Authored-By: Serhiy Storchaka +Signed-off-by: Trevor Gamblin +--- + Lib/test/test_urllib2.py | 90 ++++++++++++------- + Lib/urllib/request.py | 69 ++++++++++---- + .../2020-03-25-16-02-16.bpo-39503.YmMbYn.rst | 3 + + .../2020-01-30-16-15-29.bpo-39503.B299Yq.rst | 5 ++ + 4 files changed, 115 insertions(+), 52 deletions(-) + create mode 100644 Misc/NEWS.d/next/Library/2020-03-25-16-02-16.bpo-39503.YmMbYn.rst + create mode 100644 Misc/NEWS.d/next/Security/2020-01-30-16-15-29.bpo-39503.B299Yq.rst + +diff --git a/Lib/test/test_urllib2.py b/Lib/test/test_urllib2.py +index 8abedaac98..e69ac3e213 100644 +--- a/Lib/test/test_urllib2.py ++++ b/Lib/test/test_urllib2.py +@@ -1446,40 +1446,64 @@ class HandlerTests(unittest.TestCase): + bypass = {'exclude_simple': True, 'exceptions': []} + self.assertTrue(_proxy_bypass_macosx_sysconf('test', bypass)) + +- def test_basic_auth(self, quote_char='"'): +- opener = OpenerDirector() +- password_manager = MockPasswordManager() +- auth_handler = urllib.request.HTTPBasicAuthHandler(password_manager) +- realm = "ACME Widget Store" +- http_handler = MockHTTPHandler( +- 401, 'WWW-Authenticate: Basic realm=%s%s%s\r\n\r\n' % +- (quote_char, realm, quote_char)) +- opener.add_handler(auth_handler) +- opener.add_handler(http_handler) +- self._test_basic_auth(opener, auth_handler, "Authorization", +- realm, http_handler, password_manager, +- "http://acme.example.com/protected", +- "http://acme.example.com/protected", +- ) +- +- def test_basic_auth_with_single_quoted_realm(self): +- self.test_basic_auth(quote_char="'") +- +- def test_basic_auth_with_unquoted_realm(self): +- opener = OpenerDirector() +- password_manager = MockPasswordManager() +- auth_handler = urllib.request.HTTPBasicAuthHandler(password_manager) +- realm = "ACME Widget Store" +- http_handler = MockHTTPHandler( +- 401, 'WWW-Authenticate: Basic realm=%s\r\n\r\n' % realm) +- opener.add_handler(auth_handler) +- opener.add_handler(http_handler) +- with self.assertWarns(UserWarning): ++ def check_basic_auth(self, headers, realm): ++ with self.subTest(realm=realm, headers=headers): ++ opener = OpenerDirector() ++ password_manager = MockPasswordManager() ++ auth_handler = urllib.request.HTTPBasicAuthHandler(password_manager) ++ body = '\r\n'.join(headers) + '\r\n\r\n' ++ http_handler = MockHTTPHandler(401, body) ++ opener.add_handler(auth_handler) ++ opener.add_handler(http_handler) + self._test_basic_auth(opener, auth_handler, "Authorization", +- realm, http_handler, password_manager, +- "http://acme.example.com/protected", +- "http://acme.example.com/protected", +- ) ++ realm, http_handler, password_manager, ++ "http://acme.example.com/protected", ++ "http://acme.example.com/protected") ++ ++ def test_basic_auth(self): ++ realm = "realm2@example.com" ++ realm2 = "realm2@example.com" ++ basic = f'Basic realm="{realm}"' ++ basic2 = f'Basic realm="{realm2}"' ++ other_no_realm = 'Otherscheme xxx' ++ digest = (f'Digest realm="{realm2}", ' ++ f'qop="auth, auth-int", ' ++ f'nonce="dcd98b7102dd2f0e8b11d0f600bfb0c093", ' ++ f'opaque="5ccc069c403ebaf9f0171e9517f40e41"') ++ for realm_str in ( ++ # test "quote" and 'quote' ++ f'Basic realm="{realm}"', ++ f"Basic realm='{realm}'", ++ ++ # charset is ignored ++ f'Basic realm="{realm}", charset="UTF-8"', ++ ++ # Multiple challenges per header ++ f'{basic}, {basic2}', ++ f'{basic}, {other_no_realm}', ++ f'{other_no_realm}, {basic}', ++ f'{basic}, {digest}', ++ f'{digest}, {basic}', ++ ): ++ headers = [f'WWW-Authenticate: {realm_str}'] ++ self.check_basic_auth(headers, realm) ++ ++ # no quote: expect a warning ++ with support.check_warnings(("Basic Auth Realm was unquoted", ++ UserWarning)): ++ headers = [f'WWW-Authenticate: Basic realm={realm}'] ++ self.check_basic_auth(headers, realm) ++ ++ # Multiple headers: one challenge per header. ++ # Use the first Basic realm. ++ for challenges in ( ++ [basic, basic2], ++ [basic, digest], ++ [digest, basic], ++ ): ++ headers = [f'WWW-Authenticate: {challenge}' ++ for challenge in challenges] ++ self.check_basic_auth(headers, realm) + + def test_proxy_basic_auth(self): + opener = OpenerDirector() +diff --git a/Lib/urllib/request.py b/Lib/urllib/request.py +index 7fe50535da..2a3d71554f 100644 +--- a/Lib/urllib/request.py ++++ b/Lib/urllib/request.py +@@ -937,8 +937,15 @@ class AbstractBasicAuthHandler: + + # allow for double- and single-quoted realm values + # (single quotes are a violation of the RFC, but appear in the wild) +- rx = re.compile('(?:.*,)*[ \t]*([^ \t]+)[ \t]+' +- 'realm=(["\']?)([^"\']*)\\2', re.I) ++ rx = re.compile('(?:^|,)' # start of the string or ',' ++ '[ \t]*' # optional whitespaces ++ '([^ \t]+)' # scheme like "Basic" ++ '[ \t]+' # mandatory whitespaces ++ # realm=xxx ++ # realm='xxx' ++ # realm="xxx" ++ 'realm=(["\']?)([^"\']*)\\2', ++ re.I) + + # XXX could pre-emptively send auth info already accepted (RFC 2617, + # end of section 2, and section 1.2 immediately after "credentials" +@@ -950,27 +957,51 @@ class AbstractBasicAuthHandler: + self.passwd = password_mgr + self.add_password = self.passwd.add_password + ++ def _parse_realm(self, header): ++ # parse WWW-Authenticate header: accept multiple challenges per header ++ found_challenge = False ++ for mo in AbstractBasicAuthHandler.rx.finditer(header): ++ scheme, quote, realm = mo.groups() ++ if quote not in ['"', "'"]: ++ warnings.warn("Basic Auth Realm was unquoted", ++ UserWarning, 3) ++ ++ yield (scheme, realm) ++ ++ found_challenge = True ++ ++ if not found_challenge: ++ if header: ++ scheme = header.split()[0] ++ else: ++ scheme = '' ++ yield (scheme, None) ++ + def http_error_auth_reqed(self, authreq, host, req, headers): + # host may be an authority (without userinfo) or a URL with an + # authority +- # XXX could be multiple headers +- authreq = headers.get(authreq, None) ++ headers = headers.get_all(authreq) ++ if not headers: ++ # no header found ++ return + +- if authreq: +- scheme = authreq.split()[0] +- if scheme.lower() != 'basic': +- raise ValueError("AbstractBasicAuthHandler does not" +- " support the following scheme: '%s'" % +- scheme) +- else: +- mo = AbstractBasicAuthHandler.rx.search(authreq) +- if mo: +- scheme, quote, realm = mo.groups() +- if quote not in ['"',"'"]: +- warnings.warn("Basic Auth Realm was unquoted", +- UserWarning, 2) +- if scheme.lower() == 'basic': +- return self.retry_http_basic_auth(host, req, realm) ++ unsupported = None ++ for header in headers: ++ for scheme, realm in self._parse_realm(header): ++ if scheme.lower() != 'basic': ++ unsupported = scheme ++ continue ++ ++ if realm is not None: ++ # Use the first matching Basic challenge. ++ # Ignore following challenges even if they use the Basic ++ # scheme. ++ return self.retry_http_basic_auth(host, req, realm) ++ ++ if unsupported is not None: ++ raise ValueError("AbstractBasicAuthHandler does not " ++ "support the following scheme: %r" ++ % (scheme,)) + + def retry_http_basic_auth(self, host, req, realm): + user, pw = self.passwd.find_user_password(realm, host) +diff --git a/Misc/NEWS.d/next/Library/2020-03-25-16-02-16.bpo-39503.YmMbYn.rst b/Misc/NEWS.d/next/Library/2020-03-25-16-02-16.bpo-39503.YmMbYn.rst +new file mode 100644 +index 0000000000..be80ce79d9 +--- /dev/null ++++ b/Misc/NEWS.d/next/Library/2020-03-25-16-02-16.bpo-39503.YmMbYn.rst +@@ -0,0 +1,3 @@ ++:class:`~urllib.request.AbstractBasicAuthHandler` of :mod:`urllib.request` ++now parses all WWW-Authenticate HTTP headers and accepts multiple challenges ++per header: use the realm of the first Basic challenge. +diff --git a/Misc/NEWS.d/next/Security/2020-01-30-16-15-29.bpo-39503.B299Yq.rst b/Misc/NEWS.d/next/Security/2020-01-30-16-15-29.bpo-39503.B299Yq.rst +new file mode 100644 +index 0000000000..9f2800581c +--- /dev/null ++++ b/Misc/NEWS.d/next/Security/2020-01-30-16-15-29.bpo-39503.B299Yq.rst +@@ -0,0 +1,5 @@ ++CVE-2020-8492: The :class:`~urllib.request.AbstractBasicAuthHandler` class of the ++:mod:`urllib.request` module uses an inefficient regular expression which can ++be exploited by an attacker to cause a denial of service. Fix the regex to ++prevent the catastrophic backtracking. Vulnerability reported by Ben Caller ++and Matt Schwager. +-- +2.24.1 + diff --git a/meta/recipes-devtools/python/python3_3.8.2.bb b/meta/recipes-devtools/python/python3_3.8.2.bb index fc01935948..a4a16fd495 100644 --- a/meta/recipes-devtools/python/python3_3.8.2.bb +++ b/meta/recipes-devtools/python/python3_3.8.2.bb @@ -32,6 +32,7 @@ SRC_URI = "http://www.python.org/ftp/python/${PV}/Python-${PV}.tar.xz \ file://0001-configure.ac-fix-LIBPL.patch \ file://0001-python3-Do-not-hardcode-lib-for-distutils.patch \ file://0020-configure.ac-setup.py-do-not-add-a-curses-include-pa.patch \ + file://0001-bpo-39503-CVE-2020-8492-Fix-AbstractBasicAuthHandler.patch \ " SRC_URI_append_class-native = " \ -- cgit 1.2.3-korg