Certificate Transparency TLS extension patch for NSS

net/third_party/nss/ssl/ssl3ext.c

Index: net/third_party/nss/ssl/ssl3ext.c
diff --git a/net/third_party/nss/ssl/ssl3ext.c b/net/third_party/nss/ssl/ssl3ext.c
index 04157701e9028e670098fa47469960ffc05513c9..4b5145152c68f5704c20b7fa3af2bd69ac981a56 100644
--- a/net/third_party/nss/ssl/ssl3ext.c
+++ b/net/third_party/nss/ssl/ssl3ext.c
@@ -81,6 +81,12 @@ static PRInt32 ssl3_ClientSendSigAlgsXtn(sslSocket *ss, PRBool append,
                                          PRUint32 maxBytes);
 static SECStatus ssl3_ServerHandleSigAlgsXtn(sslSocket *ss, PRUint16 ex_type,
                                              SECItem *data);
+static PRInt32 ssl3_ClientSendSignedCertTimestampXtn(sslSocket *ss,
+						     PRBool append,
+						     PRUint32 maxBytes);
+static SECStatus ssl3_ClientHandleSignedCertTimestampXtn(sslSocket *ss,
+							 PRUint16 ex_type,
+							 SECItem *data);
 
 /*
  * Write bytes.  Using this function means the SECItem structure
@@ -259,6 +265,8 @@ static const ssl3HelloExtensionHandler serverHelloHandlersTLS[] = {
     { ssl_use_srtp_xtn,           &ssl3_HandleUseSRTPXtn },
     { ssl_channel_id_xtn,         &ssl3_ClientHandleChannelIDXtn },
     { ssl_cert_status_xtn,        &ssl3_ClientHandleStatusRequestXtn },
+    { ssl_signed_certificate_timestamp_xtn,
+      &ssl3_ClientHandleSignedCertTimestampXtn },
     { -1, NULL }
 };
 
@@ -287,7 +295,9 @@ ssl3HelloExtensionSender clientHelloSendersTLS[SSL_MAX_EXTENSIONS] = {
     { ssl_use_srtp_xtn,               &ssl3_SendUseSRTPXtn },
     { ssl_channel_id_xtn,             &ssl3_ClientSendChannelIDXtn },
     { ssl_cert_status_xtn,            &ssl3_ClientSendStatusRequestXtn },
-    { ssl_signature_algorithms_xtn,   &ssl3_ClientSendSigAlgsXtn }
+    { ssl_signature_algorithms_xtn,   &ssl3_ClientSendSigAlgsXtn },
+    { ssl_signed_certificate_timestamp_xtn,
+      &ssl3_ClientSendSignedCertTimestampXtn },

[wtc, 2013/11/08 19:51:31]

Nit: omit the comma (,).

[ekasper, 2013/11/18 17:47:18]

Done.

     /* any extra entries will appear as { 0, NULL }    */
 };
 
@@ -2297,3 +2307,60 @@ ssl3_ClientSendSigAlgsXtn(sslSocket * ss, PRBool append, PRUint32 maxBytes)
 loser:
     return -1;
 }
+
+/* ssl3_ClientSendSignedCertTimestampXtn sends the signed_certificate_timestamp
+ * extension for TLS ClientHellos. */
+static PRInt32
+ssl3_ClientSendSignedCertTimestampXtn(sslSocket *ss, PRBool append,
+				      PRUint32 maxBytes)
+{
+    /* Only send the extension if processing is enabled. */
+    if (!ss->opt.enableSignedCertTimestamps)
+	return 0;
+
+    PRInt32 extension_length = 2 /* extension_type */ +
+	    2 /* length(extension_data) */;

[wtc, 2013/11/08 19:51:31]

IMPORTANT: move the variable declaration to the beginning of the function.
Unfortunately Visual C++ still doesn't support this C99 feature.

[ekasper, 2013/11/18 17:47:18]

Done, thanks for catching this.

+
+    if (append && maxBytes >= extension_length) {
+	SECStatus rv;
+	/* extension_type */
+	rv = ssl3_AppendHandshakeNumber(ss,
+					ssl_signed_certificate_timestamp_xtn,
+					2);
+	if (rv != SECSuccess)
+	    goto loser;
+	/* zero length */
+	rv = ssl3_AppendHandshakeNumber(ss, 0, 2);
+	if (rv != SECSuccess)
+	    goto loser;
+	ss->xtnData.advertised[ss->xtnData.numAdvertised++] =
+		ssl_signed_certificate_timestamp_xtn;
+    } else if (maxBytes < extension_length) {
+	PORT_Assert(0);
+	return 0;
+    }
+
+    return extension_length;
+loser:
+    return -1;
+}
+
+static SECStatus
+ssl3_ClientHandleSignedCertTimestampXtn(sslSocket *ss, PRUint16 ex_type,
+					SECItem *data)
+{
+    /* We do not yet know whether we'll be reusing a session or creating

[wtc, 2013/11/08 19:51:31]

Nit: reusing => resuming

[ekasper, 2013/11/18 17:47:18]

I actually meant "reusing" (as in reusing the structure). But both work, so
done.

+     * a new one, so we keep a pointer to the data in the TLSExtensionData
+     * structure. This pointer is only valid in the scope of
+     * ssl3_HandleServerHello, and, if not resuming a session, a copy of the
+     * data is made once a new session has been set up.

[wtc, 2013/11/08 19:51:31]

Nit: "a copy of the data is made" => "the data is copied"

[ekasper, 2013/11/18 17:47:18]

Done.

+     * All parsing is currently left to the application and we accept
+     * everything, including empty data.
+     */
+    SECItem *scts = &ss->xtnData.signedCertTimestamps;
+    PORT_Assert(!scts->data && !scts->len);
+    *scts = *data;
+    /* Keep track of negotiated extensions. */
+    ss->xtnData.negotiated[ss->xtnData.numNegotiated++] = ex_type;
+    return SECSuccess;
+}