de85457a6c
* BaseHTTPServer: 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/python?expand=0&rev=330
77 lines
4.0 KiB
Diff
77 lines
4.0 KiB
Diff
Index: Python-2.7.18/Lib/BaseHTTPServer.py
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===================================================================
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--- Python-2.7.18.orig/Lib/BaseHTTPServer.py
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+++ Python-2.7.18/Lib/BaseHTTPServer.py
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@@ -287,6 +287,14 @@ class BaseHTTPRequestHandler(SocketServe
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return False
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self.command, self.path, self.request_version = command, path, version
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+ # CVE-2021-28861: The purpose of replacing '//' with '/' is to
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+ # protect against open redirect attacks possibly triggered if the
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+ # path starts with '//' because http clients treat //path as an
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+ # absolute URI without scheme (similar to http://path) rather than
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+ # a path.
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+ if self.path.startswith('//'):
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+ self.path = '/' + self.path.lstrip('/') # Reduce to a single /
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+
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# Examine the headers and look for a Connection directive
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self.headers = self.MessageClass(self.rfile, 0)
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Index: Python-2.7.18/Lib/test/test_httpservers.py
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===================================================================
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--- Python-2.7.18.orig/Lib/test/test_httpservers.py
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+++ Python-2.7.18/Lib/test/test_httpservers.py
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@@ -417,6 +417,52 @@ class SimpleHTTPServerTestCase(BaseTestC
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self.assertEqual(response.getheader("Location"),
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self.tempdir_name + "/?hi=1")
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+ def test_get_dir_redirect_location_domain_injection_bug(self):
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+ """Ensure //evil.co/..%2f../../X does not put //evil.co/ in Location.
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+ //netloc/ in a Location header is a redirect to a new host.
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+ https://github.com/python/cpython/issues/87389
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+ This checks that a path resolving to a directory on our server cannot
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+ resolve into a redirect to another server.
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+ """
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+ os.mkdir(os.path.join(self.tempdir, 'existing_directory'))
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+ url = '/python.org/..%2f..%2f..%2f..%2f..%2f../%0a%0d/../' + self.tempdir_name + '/existing_directory'
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+ expected_location = url + '/' # /python.org.../ single slash single prefix, trailing slash
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+ # Canonicalizes to /tmp/tempdir_name/existing_directory which does
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+ # exist and is a dir, triggering the 301 redirect logic.
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+ response = self.request(url)
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+ self.check_status_and_reason(response, 301)
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+ location = response.getheader('Location')
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+ self.assertEqual(location, expected_location, msg='non-attack failed!')
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+
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+ # //python.org... multi-slash prefix, no trailing slash
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+ attack_url = '/' + url
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+ response = self.request(attack_url)
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+ self.check_status_and_reason(response, 301)
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+ location = response.getheader('Location')
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+ self.assertFalse(location.startswith('//'), msg=location)
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+ self.assertEqual(location, expected_location,
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+ msg='Expected Location header to start with a single / and '
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+ 'end with a / as this is a directory redirect.')
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+ # ///python.org... triple-slash prefix, no trailing slash
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+ attack3_url = '//' + url
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+ response = self.request(attack3_url)
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+ self.check_status_and_reason(response, 301)
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+ self.assertEqual(response.getheader('Location'), expected_location)
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+
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+ # If the second word in the http request (Request-URI for the http
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+ # method) is a full URI, we don't worry about it, as that'll be parsed
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+ # and reassembled as a full URI within BaseHTTPRequestHandler.send_head
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+ # so no errant scheme-less //netloc//evil.co/ domain mixup can happen.
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+ attack_scheme_netloc_2slash_url = 'https://pypi.org/' + url
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+ expected_scheme_netloc_location = attack_scheme_netloc_2slash_url + '/'
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+ response = self.request(attack_scheme_netloc_2slash_url)
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+ self.check_status_and_reason(response, 301)
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+ location = response.getheader('Location')
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+ # We're just ensuring that the scheme and domain make it through, if
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+ # there are or aren't multiple slashes at the start of the path that
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+ # follows that isn't important in this Location: header.
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+ self.assertTrue(location.startswith('https://pypi.org/'), msg=location)
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+
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cgi_file1 = """\
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#!%s
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