From 3ea01e31b6d298e3849299e637e05f3a589aa415b483e71acdbb4443c917ecbc Mon Sep 17 00:00:00 2001 From: Steve Kowalik Date: Thu, 1 Sep 2022 04:20:31 +0000 Subject: [PATCH] - http.server: Fix an open redirection vulnerability in the HTTP server when an URI path starts with //. (bsc#1202624, CVE-2021-28861) OBS-URL: https://build.opensuse.org/package/show/devel:languages:python:Factory/python38?expand=0&rev=95 --- CVE-2021-28861-double-slash-path.patch | 127 +++++++++++++++++++++++++ python38.changes | 6 ++ python38.spec | 4 + 3 files changed, 137 insertions(+) create mode 100644 CVE-2021-28861-double-slash-path.patch diff --git a/CVE-2021-28861-double-slash-path.patch b/CVE-2021-28861-double-slash-path.patch new file mode 100644 index 0000000..d114856 --- /dev/null +++ b/CVE-2021-28861-double-slash-path.patch @@ -0,0 +1,127 @@ +From d01648738934922d413b65f2f97951cbab66e0bd Mon Sep 17 00:00:00 2001 +From: "Gregory P. Smith" +Date: Tue, 21 Jun 2022 13:16:57 -0700 +Subject: [PATCH] gh-87389: Fix an open redirection vulnerability in + http.server. (GH-93879) + +Fix an open redirection vulnerability in the `http.server` module when +an URI path starts with `//` that could produce a 301 Location header +with a misleading target. Vulnerability discovered, and logic fix +proposed, by Hamza Avvan (@hamzaavvan). + +Test and comments authored by Gregory P. Smith [Google]. +(cherry picked from commit 4abab6b603dd38bec1168e9a37c40a48ec89508e) + +Co-authored-by: Gregory P. Smith +--- + Lib/http/server.py | 7 +++ + Lib/test/test_httpservers.py | 53 ++++++++++++++++++- + ...2-06-15-20-09-23.gh-issue-87389.QVaC3f.rst | 3 ++ + 3 files changed, 61 insertions(+), 2 deletions(-) + create mode 100644 Misc/NEWS.d/next/Security/2022-06-15-20-09-23.gh-issue-87389.QVaC3f.rst + +diff --git a/Lib/http/server.py b/Lib/http/server.py +index 38f7accad7a3..39de35458c38 100644 +--- a/Lib/http/server.py ++++ b/Lib/http/server.py +@@ -332,6 +332,13 @@ def parse_request(self): + return False + self.command, self.path = command, path + ++ # gh-87389: The purpose of replacing '//' with '/' is to protect ++ # against open redirect attacks possibly triggered if the path starts ++ # with '//' because http clients treat //path as an absolute URI ++ # without scheme (similar to http://path) rather than a path. ++ if self.path.startswith('//'): ++ self.path = '/' + self.path.lstrip('/') # Reduce to a single / ++ + # Examine the headers and look for a Connection directive. + try: + self.headers = http.client.parse_headers(self.rfile, +diff --git a/Lib/test/test_httpservers.py b/Lib/test/test_httpservers.py +index 87d4924a34b3..fb026188f0b4 100644 +--- a/Lib/test/test_httpservers.py ++++ b/Lib/test/test_httpservers.py +@@ -330,7 +330,7 @@ class request_handler(NoLogRequestHandler, SimpleHTTPRequestHandler): + pass + + def setUp(self): +- BaseTestCase.setUp(self) ++ super().setUp() + self.cwd = os.getcwd() + basetempdir = tempfile.gettempdir() + os.chdir(basetempdir) +@@ -358,7 +358,7 @@ def tearDown(self): + except: + pass + finally: +- BaseTestCase.tearDown(self) ++ super().tearDown() + + def check_status_and_reason(self, response, status, data=None): + def close_conn(): +@@ -414,6 +414,55 @@ def test_undecodable_filename(self): + self.check_status_and_reason(response, HTTPStatus.OK, + data=support.TESTFN_UNDECODABLE) + ++ def test_get_dir_redirect_location_domain_injection_bug(self): ++ """Ensure //evil.co/..%2f../../X does not put //evil.co/ in Location. ++ ++ //netloc/ in a Location header is a redirect to a new host. ++ https://github.com/python/cpython/issues/87389 ++ ++ This checks that a path resolving to a directory on our server cannot ++ resolve into a redirect to another server. ++ """ ++ os.mkdir(os.path.join(self.tempdir, 'existing_directory')) ++ url = f'/python.org/..%2f..%2f..%2f..%2f..%2f../%0a%0d/../{self.tempdir_name}/existing_directory' ++ expected_location = f'{url}/' # /python.org.../ single slash single prefix, trailing slash ++ # Canonicalizes to /tmp/tempdir_name/existing_directory which does ++ # exist and is a dir, triggering the 301 redirect logic. ++ response = self.request(url) ++ self.check_status_and_reason(response, HTTPStatus.MOVED_PERMANENTLY) ++ location = response.getheader('Location') ++ self.assertEqual(location, expected_location, msg='non-attack failed!') ++ ++ # //python.org... multi-slash prefix, no trailing slash ++ attack_url = f'/{url}' ++ response = self.request(attack_url) ++ self.check_status_and_reason(response, HTTPStatus.MOVED_PERMANENTLY) ++ location = response.getheader('Location') ++ self.assertFalse(location.startswith('//'), msg=location) ++ self.assertEqual(location, expected_location, ++ msg='Expected Location header to start with a single / and ' ++ 'end with a / as this is a directory redirect.') ++ ++ # ///python.org... triple-slash prefix, no trailing slash ++ attack3_url = f'//{url}' ++ response = self.request(attack3_url) ++ self.check_status_and_reason(response, HTTPStatus.MOVED_PERMANENTLY) ++ self.assertEqual(response.getheader('Location'), expected_location) ++ ++ # If the second word in the http request (Request-URI for the http ++ # method) is a full URI, we don't worry about it, as that'll be parsed ++ # and reassembled as a full URI within BaseHTTPRequestHandler.send_head ++ # so no errant scheme-less //netloc//evil.co/ domain mixup can happen. ++ attack_scheme_netloc_2slash_url = f'https://pypi.org/{url}' ++ expected_scheme_netloc_location = f'{attack_scheme_netloc_2slash_url}/' ++ response = self.request(attack_scheme_netloc_2slash_url) ++ self.check_status_and_reason(response, HTTPStatus.MOVED_PERMANENTLY) ++ location = response.getheader('Location') ++ # We're just ensuring that the scheme and domain make it through, if ++ # there are or aren't multiple slashes at the start of the path that ++ # follows that isn't important in this Location: header. ++ self.assertTrue(location.startswith('https://pypi.org/'), msg=location) ++ + def test_get(self): + #constructs the path relative to the root directory of the HTTPServer + response = self.request(self.base_url + '/test') +diff --git a/Misc/NEWS.d/next/Security/2022-06-15-20-09-23.gh-issue-87389.QVaC3f.rst b/Misc/NEWS.d/next/Security/2022-06-15-20-09-23.gh-issue-87389.QVaC3f.rst +new file mode 100644 +index 000000000000..029d437190de +--- /dev/null ++++ b/Misc/NEWS.d/next/Security/2022-06-15-20-09-23.gh-issue-87389.QVaC3f.rst +@@ -0,0 +1,3 @@ ++:mod:`http.server`: Fix an open redirection vulnerability in the HTTP server ++when an URI path starts with ``//``. Vulnerability discovered, and initial ++fix proposed, by Hamza Avvan. diff --git a/python38.changes b/python38.changes index ab114a3..ff68293 100644 --- a/python38.changes +++ b/python38.changes @@ -1,3 +1,9 @@ +------------------------------------------------------------------- +Thu Sep 1 04:20:04 UTC 2022 - Steve Kowalik + +- http.server: Fix an open redirection vulnerability in the HTTP server + when an URI path starts with //. (bsc#1202624, CVE-2021-28861) + ------------------------------------------------------------------- Wed Aug 31 08:47:57 UTC 2022 - Matej Cepl diff --git a/python38.spec b/python38.spec index b88c2ec..23c9d8b 100644 --- a/python38.spec +++ b/python38.spec @@ -167,6 +167,9 @@ Patch33: bpo44426-complex-keyword-sphinx.patch # PATCH-FIX-UPSTREAM bpo34990-2038-problem-compileall.patch gh#python/cpython#79171 mcepl@suse.com # Make compileall.py compatible with year 2038 Patch34: bpo34990-2038-problem-compileall.patch +# PATCH-FIX-UPSTREAM CVE-2021-28861 bsc#1202624 gh#python/cpython#94094 +# Coerce // to / in Lib/http/server.py +Patch35: CVE-2021-28861-double-slash-path.patch BuildRequires: autoconf-archive BuildRequires: automake BuildRequires: fdupes @@ -432,6 +435,7 @@ other applications. %patch32 -p1 %patch33 -p1 %patch34 -p1 +%patch35 -p1 # drop Autoconf version requirement sed -i 's/^AC_PREREQ/dnl AC_PREREQ/' configure.ac