From 1bd50d351e508b8947e5813c5f925eb4b61c8d76 Mon Sep 17 00:00:00 2001
From: Xtreak <tir.karthi@gmail.com>
Date: Sat, 15 Jun 2019 20:59:43 +0530
Subject: [PATCH] [2.7] bpo-35121: prefix dot in domain for proper subdomain
 validation (GH-10258) (GH-13426)

This is a manual backport of ca7fe5063593958e5efdf90f068582837f07bd14 since 2.7 has `http.cookiejar` in `cookielib`

https://bugs.python.org/issue35121

CVE: CVE-2018-20852
Upstream-Status: Accepted

Signed-off-by: Dan Tran <dantran@microsoft.com>
---
 Lib/cookielib.py                              | 13 ++++++--
 Lib/test/test_cookielib.py                    | 30 +++++++++++++++++++
 .../2019-05-20-00-35-12.bpo-35121.RRi-HU.rst  |  4 +++
 3 files changed, 45 insertions(+), 2 deletions(-)
 create mode 100644 Misc/NEWS.d/next/Security/2019-05-20-00-35-12.bpo-35121.RRi-HU.rst

diff --git a/Lib/cookielib.py b/Lib/cookielib.py
index 2dd7c48728..0b471a42f2 100644
--- a/Lib/cookielib.py
+++ b/Lib/cookielib.py
@@ -1139,6 +1139,11 @@ class DefaultCookiePolicy(CookiePolicy):
         req_host, erhn = eff_request_host(request)
         domain = cookie.domain
 
+        if domain and not domain.startswith("."):
+            dotdomain = "." + domain
+        else:
+            dotdomain = domain
+
         # strict check of non-domain cookies: Mozilla does this, MSIE5 doesn't
         if (cookie.version == 0 and
             (self.strict_ns_domain & self.DomainStrictNonDomain) and
@@ -1151,7 +1156,7 @@ class DefaultCookiePolicy(CookiePolicy):
             _debug("   effective request-host name %s does not domain-match "
                    "RFC 2965 cookie domain %s", erhn, domain)
             return False
-        if cookie.version == 0 and not ("."+erhn).endswith(domain):
+        if cookie.version == 0 and not ("."+erhn).endswith(dotdomain):
             _debug("   request-host %s does not match Netscape cookie domain "
                    "%s", req_host, domain)
             return False
@@ -1165,7 +1170,11 @@ class DefaultCookiePolicy(CookiePolicy):
             req_host = "."+req_host
         if not erhn.startswith("."):
             erhn = "."+erhn
-        if not (req_host.endswith(domain) or erhn.endswith(domain)):
+        if domain and not domain.startswith("."):
+            dotdomain = "." + domain
+        else:
+            dotdomain = domain
+        if not (req_host.endswith(dotdomain) or erhn.endswith(dotdomain)):
             #_debug("   request domain %s does not match cookie domain %s",
             #       req_host, domain)
             return False
diff --git a/Lib/test/test_cookielib.py b/Lib/test/test_cookielib.py
index f2dd9727d1..7f7ff614d6 100644
--- a/Lib/test/test_cookielib.py
+++ b/Lib/test/test_cookielib.py
@@ -368,6 +368,7 @@ class CookieTests(TestCase):
             ("http://foo.bar.com/", ".foo.bar.com", True),
             ("http://foo.bar.com/", "foo.bar.com", True),
             ("http://foo.bar.com/", ".bar.com", True),
+            ("http://foo.bar.com/", "bar.com", True),
             ("http://foo.bar.com/", "com", True),
             ("http://foo.com/", "rhubarb.foo.com", False),
             ("http://foo.com/", ".foo.com", True),
@@ -378,6 +379,8 @@ class CookieTests(TestCase):
             ("http://foo/", "foo", True),
             ("http://foo/", "foo.local", True),
             ("http://foo/", ".local", True),
+            ("http://barfoo.com", ".foo.com", False),
+            ("http://barfoo.com", "foo.com", False),
             ]:
             request = urllib2.Request(url)
             r = pol.domain_return_ok(domain, request)
@@ -938,6 +941,33 @@ class CookieTests(TestCase):
         c.add_cookie_header(req)
         self.assertFalse(req.has_header("Cookie"))
 
+        c.clear()
+
+        pol.set_blocked_domains([])
+        req = Request("http://acme.com/")
+        res = FakeResponse(headers, "http://acme.com/")
+        cookies = c.make_cookies(res, req)
+        c.extract_cookies(res, req)
+        self.assertEqual(len(c), 1)
+
+        req = Request("http://acme.com/")
+        c.add_cookie_header(req)
+        self.assertTrue(req.has_header("Cookie"))
+
+        req = Request("http://badacme.com/")
+        c.add_cookie_header(req)
+        self.assertFalse(pol.return_ok(cookies[0], req))
+        self.assertFalse(req.has_header("Cookie"))
+
+        p = pol.set_blocked_domains(["acme.com"])
+        req = Request("http://acme.com/")
+        c.add_cookie_header(req)
+        self.assertFalse(req.has_header("Cookie"))
+
+        req = Request("http://badacme.com/")
+        c.add_cookie_header(req)
+        self.assertFalse(req.has_header("Cookie"))
+
     def test_secure(self):
         from cookielib import CookieJar, DefaultCookiePolicy
 
diff --git a/Misc/NEWS.d/next/Security/2019-05-20-00-35-12.bpo-35121.RRi-HU.rst b/Misc/NEWS.d/next/Security/2019-05-20-00-35-12.bpo-35121.RRi-HU.rst
new file mode 100644
index 0000000000..7725180616
--- /dev/null
+++ b/Misc/NEWS.d/next/Security/2019-05-20-00-35-12.bpo-35121.RRi-HU.rst
@@ -0,0 +1,4 @@
+Don't send cookies of domain A without Domain attribute to domain B when
+domain A is a suffix match of domain B while using a cookiejar with
+:class:`cookielib.DefaultCookiePolicy` policy. Patch by Karthikeyan
+Singaravelan.
-- 
2.22.0.vfs.1.1.57.gbaf16c8

