- Issue #18709: Fix CVE-2013-4238. The SSL module now handles NULL bytes

  inside subjectAltName correctly. Formerly the module has used OpenSSL's
  GENERAL_NAME_print() function to get the string represention of ASN.1
  strings for `rfc822Name` (email), `dNSName` (DNS) and
  `uniformResourceIdentifier` (URI).

Lib/test/keycert.pem

------BEGIN RSA PRIVATE KEY-----
-MIICXwIBAAKBgQC8ddrhm+LutBvjYcQlnH21PPIseJ1JVG2HMmN2CmZk2YukO+9L
-opdJhTvbGfEj0DQs1IE8M+kTUyOmuKfVrFMKwtVeCJphrAnhoz7TYOuLBSqt7lVH
-fhi/VwovESJlaBOp+WMnfhcduPEYHYx/6cnVapIkZnLt30zu2um+DzA9jQIDAQAB
-AoGBAK0FZpaKj6WnJZN0RqhhK+ggtBWwBnc0U/ozgKz2j1s3fsShYeiGtW6CK5nU
-D1dZ5wzhbGThI7LiOXDvRucc9n7vUgi0alqPQ/PFodPxAN/eEYkmXQ7W2k7zwsDA
-IUK0KUhktQbLu8qF/m8qM86ba9y9/9YkXuQbZ3COl5ahTZrhAkEA301P08RKv3KM
-oXnGU2UHTuJ1MAD2hOrPxjD4/wxA/39EWG9bZczbJyggB4RHu0I3NOSFjAm3HQm0
-ANOu5QK9owJBANgOeLfNNcF4pp+UikRFqxk5hULqRAWzVxVrWe85FlPm0VVmHbb/
-loif7mqjU8o1jTd/LM7RD9f2usZyE2psaw8CQQCNLhkpX3KO5kKJmS9N7JMZSc4j
-oog58yeYO8BBqKKzpug0LXuQultYv2K4veaIO04iL9VLe5z9S/Q1jaCHBBuXAkEA
-z8gjGoi1AOp6PBBLZNsncCvcV/0aC+1se4HxTNo2+duKSDnbq+ljqOM+E7odU+Nq
-ewvIWOG//e8fssd0mq3HywJBAJ8l/c8GVmrpFTx8r/nZ2Pyyjt3dH1widooDXYSV
-q6Gbf41Llo5sYAtmxdndTLASuHKecacTgZVhy0FryZpLKrU=
------END RSA PRIVATE KEY-----
+-----BEGIN PRIVATE KEY-----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+-----END PRIVATE KEY-----
 -----BEGIN CERTIFICATE-----
-MIICpzCCAhCgAwIBAgIJAP+qStv1cIGNMA0GCSqGSIb3DQEBBQUAMIGJMQswCQYD
-VQQGEwJVUzERMA8GA1UECBMIRGVsYXdhcmUxEzARBgNVBAcTCldpbG1pbmd0b24x
-IzAhBgNVBAoTGlB5dGhvbiBTb2Z0d2FyZSBGb3VuZGF0aW9uMQwwCgYDVQQLEwNT
-U0wxHzAdBgNVBAMTFnNvbWVtYWNoaW5lLnB5dGhvbi5vcmcwHhcNMDcwODI3MTY1
-NDUwWhcNMTMwMjE2MTY1NDUwWjCBiTELMAkGA1UEBhMCVVMxETAPBgNVBAgTCERl
-bGF3YXJlMRMwEQYDVQQHEwpXaWxtaW5ndG9uMSMwIQYDVQQKExpQeXRob24gU29m
-dHdhcmUgRm91bmRhdGlvbjEMMAoGA1UECxMDU1NMMR8wHQYDVQQDExZzb21lbWFj
-aGluZS5weXRob24ub3JnMIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQC8ddrh
-m+LutBvjYcQlnH21PPIseJ1JVG2HMmN2CmZk2YukO+9LopdJhTvbGfEj0DQs1IE8
-M+kTUyOmuKfVrFMKwtVeCJphrAnhoz7TYOuLBSqt7lVHfhi/VwovESJlaBOp+WMn
-fhcduPEYHYx/6cnVapIkZnLt30zu2um+DzA9jQIDAQABoxUwEzARBglghkgBhvhC
-AQEEBAMCBkAwDQYJKoZIhvcNAQEFBQADgYEAF4Q5BVqmCOLv1n8je/Jw9K669VXb
-08hyGzQhkemEBYQd6fzQ9A/1ZzHkJKb1P6yreOLSEh4KcxYPyrLRC1ll8nr5OlCx
-CMhKkTnR6qBsdNV0XtdU2+N25hqW+Ma4ZeqsN/iiJVCGNOZGnvQuvCAGWF8+J/f/
-iHkC6gGdBJhogs4=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 -----END CERTIFICATE-----

Lib/test/nullbytecert.pem

+Certificate:
+    Data:
+        Version: 3 (0x2)
+        Serial Number: 0 (0x0)
+    Signature Algorithm: sha1WithRSAEncryption
+        Issuer: C=US, ST=Oregon, L=Beaverton, O=Python Software Foundation, OU=Python Core Development, CN=null.python.org\x00example.org/emailAddress=python-dev@python.org
+        Validity
+            Not Before: Aug  7 13:11:52 2013 GMT
+            Not After : Aug  7 13:12:52 2013 GMT
+        Subject: C=US, ST=Oregon, L=Beaverton, O=Python Software Foundation, OU=Python Core Development, CN=null.python.org\x00example.org/emailAddress=python-dev@python.org
+        Subject Public Key Info:
+            Public Key Algorithm: rsaEncryption
+                Public-Key: (2048 bit)
+                Modulus:
+                    00:b5:ea:ed:c9:fb:46:7d:6f:3b:76:80:dd:3a:f3:
+                    03:94:0b:a7:a6:db:ec:1d:df:ff:23:74:08:9d:97:
+                    16:3f:a3:a4:7b:3e:1b:0e:96:59:25:03:a7:26:e2:
+                    88:a9:cf:79:cd:f7:04:56:b0:ab:79:32:6e:59:c1:
+                    32:30:54:eb:58:a8:cb:91:f0:42:a5:64:27:cb:d4:
+                    56:31:88:52:ad:cf:bd:7f:f0:06:64:1f:cc:27:b8:
+                    a3:8b:8c:f3:d8:29:1f:25:0b:f5:46:06:1b:ca:02:
+                    45:ad:7b:76:0a:9c:bf:bb:b9:ae:0d:16:ab:60:75:
+                    ae:06:3e:9c:7c:31:dc:92:2f:29:1a:e0:4b:0c:91:
+                    90:6c:e9:37:c5:90:d7:2a:d7:97:15:a3:80:8f:5d:
+                    7b:49:8f:54:30:d4:97:2c:1c:5b:37:b5:ab:69:30:
+                    68:43:d3:33:78:4b:02:60:f5:3c:44:80:a1:8f:e7:
+                    f0:0f:d1:5e:87:9e:46:cf:62:fc:f9:bf:0c:65:12:
+                    f1:93:c8:35:79:3f:c8:ec:ec:47:f5:ef:be:44:d5:
+                    ae:82:1e:2d:9a:9f:98:5a:67:65:e1:74:70:7c:cb:
+                    d3:c2:ce:0e:45:49:27:dc:e3:2d:d4:fb:48:0e:2f:
+                    9e:77:b8:14:46:c0:c4:36:ca:02:ae:6a:91:8c:da:
+                    2f:85
+                Exponent: 65537 (0x10001)
+        X509v3 extensions:
+            X509v3 Basic Constraints: critical
+                CA:FALSE
+            X509v3 Subject Key Identifier:
+                88:5A:55:C0:52:FF:61:CD:52:A3:35:0F:EA:5A:9C:24:38:22:F7:5C
+            X509v3 Key Usage:
+                Digital Signature, Non Repudiation, Key Encipherment
+            X509v3 Subject Alternative Name:
+                *************************************************************
+                WARNING: The values for DNS, email and URI are WRONG. OpenSSL
+                         doesn't print the text after a NULL byte.
+                *************************************************************
+                DNS:altnull.python.org, email:null@python.org, URI:http://null.python.org, IP Address:192.0.2.1, IP Address:2001:DB8:0:0:0:0:0:1
+    Signature Algorithm: sha1WithRSAEncryption
+         ac:4f:45:ef:7d:49:a8:21:70:8e:88:59:3e:d4:36:42:70:f5:
+         a3:bd:8b:d7:a8:d0:58:f6:31:4a:b1:a4:a6:dd:6f:d9:e8:44:
+         3c:b6:0a:71:d6:7f:b1:08:61:9d:60:ce:75:cf:77:0c:d2:37:
+         86:02:8d:5e:5d:f9:0f:71:b4:16:a8:c1:3d:23:1c:f1:11:b3:
+         56:6e:ca:d0:8d:34:94:e6:87:2a:99:f2:ae:ae:cc:c2:e8:86:
+         de:08:a8:7f:c5:05:fa:6f:81:a7:82:e6:d0:53:9d:34:f4:ac:
+         3e:40:fe:89:57:7a:29:a4:91:7e:0b:c6:51:31:e5:10:2f:a4:
+         60:76:cd:95:51:1a:be:8b:a1:b0:fd:ad:52:bd:d7:1b:87:60:
+         d2:31:c7:17:c4:18:4f:2d:08:25:a3:a7:4f:b7:92:ca:e2:f5:
+         25:f1:54:75:81:9d:b3:3d:61:a2:f7:da:ed:e1:c6:6f:2c:60:
+         1f:d8:6f:c5:92:05:ab:c9:09:62:49:a9:14:ad:55:11:cc:d6:
+         4a:19:94:99:97:37:1d:81:5f:8b:cf:a3:a8:96:44:51:08:3d:
+         0b:05:65:12:eb:b6:70:80:88:48:72:4f:c6:c2:da:cf:cd:8e:
+         5b:ba:97:2f:60:b4:96:56:49:5e:3a:43:76:63:04:be:2a:f6:
+         c1:ca:a9:94
+-----BEGIN CERTIFICATE-----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=
+-----END CERTIFICATE-----

Lib/test/test_ssl.py

@@ -31,6 +31,7 @@ except ImportError:
 HOST = test_support.HOST
 CERTFILE = None
 SVN_PYTHON_ORG_ROOT_CERT = None
+NULLBYTECERT = None
 
 def handle_error(prefix):
     exc_format = ' '.join(traceback.format_exception(*sys.exc_info()))
@@ -88,6 +89,27 @@ class BasicTests(unittest.TestCase):
         if test_support.verbose:
             sys.stdout.write("\n" + pprint.pformat(p) + "\n")
 
+    def test_parse_cert_CVE_2013_4073(self):
+        p = ssl._ssl._test_decode_cert(NULLBYTECERT)
+        if test_support.verbose:
+            sys.stdout.write("\n" + pprint.pformat(p) + "\n")
+        subject = ((('countryName', 'US'),),
+                   (('stateOrProvinceName', 'Oregon'),),
+                   (('localityName', 'Beaverton'),),
+                   (('organizationName', 'Python Software Foundation'),),
+                   (('organizationalUnitName', 'Python Core Development'),),
+                   (('commonName', 'null.python.org\x00example.org'),),
+                   (('emailAddress', 'python-dev@python.org'),))
+        self.assertEqual(p['subject'], subject)
+        self.assertEqual(p['issuer'], subject)
+        self.assertEqual(p['subjectAltName'],
+                         (('DNS', 'altnull.python.org\x00example.com'),
+                         ('email', 'null@python.org\x00user@example.org'),
+                         ('URI', 'http://null.python.org\x00http://example.org'),
+                         ('IP Address', '192.0.2.1'),
+                         ('IP Address', '2001:DB8:0:0:0:0:0:1\n'))
+                        )
+
     def test_DER_to_PEM(self):
         with open(SVN_PYTHON_ORG_ROOT_CERT, 'r') as f:
             pem = f.read()
@@ -1210,15 +1232,18 @@ def test_main(verbose=False):
     if skip_expected:
         raise test_support.TestSkipped("No SSL support")
 
-    global CERTFILE, SVN_PYTHON_ORG_ROOT_CERT
+    global CERTFILE, SVN_PYTHON_ORG_ROOT_CERT, NULLBYTECERT
     CERTFILE = os.path.join(os.path.dirname(__file__) or os.curdir,
                             "keycert.pem")
     SVN_PYTHON_ORG_ROOT_CERT = os.path.join(
         os.path.dirname(__file__) or os.curdir,
         "https_svn_python_org_root.pem")
+    NULLBYTECERT = os.path.join(os.path.dirname(__file__) or os.curdir,
+                                "nullbytecert.pem")
 
     if (not os.path.exists(CERTFILE) or
-        not os.path.exists(SVN_PYTHON_ORG_ROOT_CERT)):
+        not os.path.exists(SVN_PYTHON_ORG_ROOT_CERT) or
+        not os.path.exists(NULLBYTECERT)):
         raise test_support.TestFailed("Can't read certificate files!")
 
     tests = [BasicTests]

Misc/NEWS

@@ -16,6 +16,15 @@ Library
 - Issue #16248: Disable code execution from the user's home directory by
   tkinter when the -E flag is passed to Python.  Patch by Zachary Ware.
 
+Extension Modules
+-----------------
+
+- Issue #18709: Fix CVE-2013-4238. The SSL module now handles NULL bytes
+  inside subjectAltName correctly. Formerly the module has used OpenSSL's
+  GENERAL_NAME_print() function to get the string represention of ASN.1
+  strings for `rfc822Name` (email), `dNSName` (DNS) and 
+  `uniformResourceIdentifier` (URI).
+
 
 What's New in Python 2.6.8?
 ===========================

Modules/_ssl.c

@@ -302,8 +302,10 @@ newPySSLObject(PySocketSockObject *Sock, char *key_file, char *cert_file,
         self->ctx = SSL_CTX_new(TLSv1_method()); /* Set up context */
     else if (proto_version == PY_SSL_VERSION_SSL3)
         self->ctx = SSL_CTX_new(SSLv3_method()); /* Set up context */
+#ifndef OPENSSL_NO_SSL2
     else if (proto_version == PY_SSL_VERSION_SSL2)
         self->ctx = SSL_CTX_new(SSLv2_method()); /* Set up context */
+#endif
     else if (proto_version == PY_SSL_VERSION_SSL23)
         self->ctx = SSL_CTX_new(SSLv23_method()); /* Set up context */
     PySSL_END_ALLOW_THREADS
@@ -718,8 +720,13 @@ _get_peer_alt_names (X509 *certificate) {
 
             /* get a rendering of each name in the set of names */
 
+            int gntype;
+            ASN1_STRING *as = NULL;
+
             name = sk_GENERAL_NAME_value(names, j);
-            if (name->type == GEN_DIRNAME) {
+            gntype = name-> type;
+            switch (gntype) {
+            case GEN_DIRNAME:
 
                 /* we special-case DirName as a tuple of tuples of attributes */
 
@@ -741,11 +748,61 @@ _get_peer_alt_names (X509 *certificate) {
                     goto fail;
                 }
                 PyTuple_SET_ITEM(t, 1, v);
+                break;
 
-            } else {
+            case GEN_EMAIL:
+            case GEN_DNS:
+            case GEN_URI:
+                /* GENERAL_NAME_print() doesn't handle NUL bytes in ASN1_string
+                   correctly. */
+                t = PyTuple_New(2);
+                if (t == NULL)
+                    goto fail;
+                switch (gntype) {
+                case GEN_EMAIL:
+                    v = PyUnicode_FromString("email");
+                    as = name->d.rfc822Name;
+                    break;
+                case GEN_DNS:
+                    v = PyUnicode_FromString("DNS");
+                    as = name->d.dNSName;
+                    break;
+                case GEN_URI:
+                    v = PyUnicode_FromString("URI");
+                    as = name->d.uniformResourceIdentifier;
+                    break;
+                }
+                if (v == NULL) {
+                    Py_DECREF(t);
+                    goto fail;
+                }
+                PyTuple_SET_ITEM(t, 0, v);
+                v = PyString_FromStringAndSize((char *)ASN1_STRING_data(as),
+                                               ASN1_STRING_length(as));
+                if (v == NULL) {
+                    Py_DECREF(t);
+                    goto fail;
+                }
+                PyTuple_SET_ITEM(t, 1, v);
+                break;
 
+            default:
                 /* for everything else, we use the OpenSSL print form */
-
+                switch (gntype) {
+                    /* check for new general name type */
+                    case GEN_OTHERNAME:
+                    case GEN_X400:
+                    case GEN_EDIPARTY:
+                    case GEN_IPADD:
+                    case GEN_RID:
+                        break;
+                    default:
+                        if (PyErr_Warn(PyExc_RuntimeWarning,
+				       "Unknown general name type") == -1) {
+                            goto fail;
+                        }
+                        break;
+                }
                 (void) BIO_reset(biobuf);
                 GENERAL_NAME_print(biobuf, name);
                 len = BIO_gets(biobuf, buf, sizeof(buf)-1);
@@ -771,6 +828,7 @@ _get_peer_alt_names (X509 *certificate) {
                     goto fail;
                 }
                 PyTuple_SET_ITEM(t, 1, v);
+		break;
             }
 
             /* and add that rendering to the list */