Add http.coookies monkeypatch (SYN-8465)

changes/bd45773cff22d0cf547370e90918ba58.yaml

@@ -0,0 +1,5 @@
+---
+desc: Added a patch for Python ``http.cookies`` module to address CVE-2024-7592 exposure.
+prs: []
+type: bug
+...

synapse/common.py

@@ -29,6 +29,8 @@
 import contextlib
 import collections
 
+import http.cookies
+
 import yaml
 import regex
 
@@ -38,6 +40,8 @@
 import synapse.lib.structlog as s_structlog
 
 import synapse.vendor.cpython.lib.ipaddress as ipaddress
+import synapse.vendor.cpython.lib.http.cookies as v_cookies
+
 
 try:
     from yaml import CSafeLoader as Loader
@@ -1218,6 +1222,17 @@
     assert n > plen
     return f'{text[:mlen]}{placeholder}'
 
+def _patch_http_cookies():
+    '''
+    Patch stdlib http.cookies._unquote from the 3.11.10 implementation if
+    the interpreter we are using is not patched for CVE-2024-7592.
+    '''
+    if not hasattr(http.cookies, '_QuotePatt'):
+        return
+    http.cookies._unquote = v_cookies._unquote
+
+_patch_http_cookies()
+
 # TODO:  Switch back to using asyncio.wait_for when we are using py 3.12+
 # This is a workaround for a race where asyncio.wait_for can end up
 # ignoring cancellation https://github.com/python/cpython/issues/86296

synapse/vendor/cpython/lib/http/cookies.py

@@ -0,0 +1,59 @@
+##############################################################################
+# Taken from the cpython 3.11 source branch after the 3.11.10 release.
+##############################################################################
+####
+# Copyright 2000 by Timothy O'Malley <timo@alum.mit.edu>
+#
+#                All Rights Reserved
+#
+# Permission to use, copy, modify, and distribute this software
+# and its documentation for any purpose and without fee is hereby
+# granted, provided that the above copyright notice appear in all
+# copies and that both that copyright notice and this permission
+# notice appear in supporting documentation, and that the name of
+# Timothy O'Malley  not be used in advertising or publicity
+# pertaining to distribution of the software without specific, written
+# prior permission.
+#
+# Timothy O'Malley DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS
+# SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+# AND FITNESS, IN NO EVENT SHALL Timothy O'Malley BE LIABLE FOR
+# ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
+# WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
+# ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+# PERFORMANCE OF THIS SOFTWARE.
+#
+
+#
+# Import our required modules
+#
+import re
+
+_unquote_sub = re.compile(r'\\(?:([0-3][0-7][0-7])|(.))').sub
+
+def _unquote_replace(m):
+    if m[1]:
+        return chr(int(m[1], 8))
+    else:
+        return m[2]
+
+def _unquote(str):
+    # If there aren't any doublequotes,
+    # then there can't be any special characters.  See RFC 2109.
+    if str is None or len(str) < 2:
+        return str
+    if str[0] != '"' or str[-1] != '"':
+        return str
+
+    # We have to assume that we must decode this string.
+    # Down to work.
+
+    # Remove the "s
+    str = str[1:-1]
+
+    # Check for special sequences.  Examples:
+    #    \012 --> \n
+    #    \"   --> "
+    #
+    return _unquote_sub(_unquote_replace, str)

synapse/vendor/cpython/lib/test/test_http_cookies.py

@@ -0,0 +1,49 @@
+##############################################################################
+# Taken from the cpython 3.11 source branch after the 3.11.10 release.
+# It has been modified for vendored imports and vendored test harness.
+##############################################################################
+
+# Simple test suite for http/cookies.py
+
+from http import cookies
+
+# s_v_utils runs the monkeypatch
+import synapse.vendor.utils as s_v_utils
+
+class CookieTests(s_v_utils.VendorTest):
+
+    def test_unquote(self):
+        cases = [
+            (r'a="b=\""', 'b="'),
+            (r'a="b=\\"', 'b=\\'),
+            (r'a="b=\="', 'b=='),
+            (r'a="b=\n"', 'b=n'),
+            (r'a="b=\042"', 'b="'),
+            (r'a="b=\134"', 'b=\\'),
+            (r'a="b=\377"', 'b=\xff'),
+            (r'a="b=\400"', 'b=400'),
+            (r'a="b=\42"', 'b=42'),
+            (r'a="b=\\042"', 'b=\\042'),
+            (r'a="b=\\134"', 'b=\\134'),
+            (r'a="b=\\\""', 'b=\\"'),
+            (r'a="b=\\\042"', 'b=\\"'),
+            (r'a="b=\134\""', 'b=\\"'),
+            (r'a="b=\134\042"', 'b=\\"'),
+        ]
+        for encoded, decoded in cases:
+            with self.subTest(encoded):
+                C = cookies.SimpleCookie()
+                C.load(encoded)
+                self.assertEqual(C['a'].value, decoded)
+
+    def test_unquote_large(self):
+        n = 10**6
+        for encoded in r'\\', r'\134':
+            with self.subTest(encoded):
+                data = 'a="b=' + encoded * n + ';"'
+                C = cookies.SimpleCookie()
+                C.load(data)
+                value = C['a'].value
+                self.assertEqual(value[:3], 'b=\\')
+                self.assertEqual(value[-2:], '\\;')
+                self.assertEqual(len(value), n + 3)