crypto: emulate OpenSSL 1.0 ticket scheme in 1.1

davidben · rvagg · commit f72975ffa29b · 2017-11-11T20:42:50.000+11:00
OpenSSL 1.0.x used a 48-byte ticket key, but OpenSSL 1.1.x made it larger by using a larger HMAC-SHA256 key and using AES-256-CBC to encrypt. However, Node's public API exposes the 48-byte key. Implement the ticket key callback to restore the OpenSSL 1.0.x behavior. PR-URL: nodejs#16130 Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl> Reviewed-By: Rod Vagg <rod@vagg.org>
diff --git a/src/node_crypto.cc b/src/node_crypto.cc
@@ -608,6 +608,19 @@ void SecureContext::Init(const FunctionCallbackInfo<Value>& args) {
                                  SSL_SESS_CACHE_NO_AUTO_CLEAR);
   SSL_CTX_sess_set_get_cb(sc->ctx_, SSLWrap<Connection>::GetSessionCallback);
   SSL_CTX_sess_set_new_cb(sc->ctx_, SSLWrap<Connection>::NewSessionCallback);
+
+#if OPENSSL_VERSION_NUMBER >= 0x10100000L
+  // OpenSSL 1.1.0 changed the ticket key size, but the OpenSSL 1.0.x size was
+  // exposed in the public API. To retain compatibility, install a callback
+  // which restores the old algorithm.
+  if (RAND_bytes(sc->ticket_key_name_, sizeof(sc->ticket_key_name_)) <= 0 ||
+      RAND_bytes(sc->ticket_key_hmac_, sizeof(sc->ticket_key_hmac_)) <= 0 ||
+      RAND_bytes(sc->ticket_key_aes_, sizeof(sc->ticket_key_aes_)) <= 0) {
+    return env->ThrowError("Error generating ticket keys");
+  }
+  SSL_CTX_set_tlsext_ticket_key_cb(sc->ctx_,
+                                   SecureContext::TicketCompatibilityCallback);
+#endif
 }
 
 
@@ -1285,11 +1298,17 @@ void SecureContext::GetTicketKeys(const FunctionCallbackInfo<Value>& args) {
   ASSIGN_OR_RETURN_UNWRAP(&wrap, args.Holder());
 
   Local<Object> buff = Buffer::New(wrap->env(), 48).ToLocalChecked();
+#if OPENSSL_VERSION_NUMBER >= 0x10100000L
+  memcpy(Buffer::Data(buff), wrap->ticket_key_name_, 16);
+  memcpy(Buffer::Data(buff) + 16, wrap->ticket_key_hmac_, 16);
+  memcpy(Buffer::Data(buff) + 32, wrap->ticket_key_aes_, 16);
+#else
   if (SSL_CTX_get_tlsext_ticket_keys(wrap->ctx_,
                                      Buffer::Data(buff),
                                      Buffer::Length(buff)) != 1) {
     return wrap->env()->ThrowError("Failed to fetch tls ticket keys");
   }
+#endif
 
   args.GetReturnValue().Set(buff);
 #endif  // !def(OPENSSL_NO_TLSEXT) && def(SSL_CTX_get_tlsext_ticket_keys)
@@ -1312,11 +1331,17 @@ void SecureContext::SetTicketKeys(const FunctionCallbackInfo<Value>& args) {
     return env->ThrowTypeError("Ticket keys length must be 48 bytes");
   }
 
+#if OPENSSL_VERSION_NUMBER >= 0x10100000L
+  memcpy(wrap->ticket_key_name_, Buffer::Data(args[0]), 16);
+  memcpy(wrap->ticket_key_hmac_, Buffer::Data(args[0]) + 16, 16);
+  memcpy(wrap->ticket_key_aes_, Buffer::Data(args[0]) + 32, 16);
+#else
   if (SSL_CTX_set_tlsext_ticket_keys(wrap->ctx_,
                                      Buffer::Data(args[0]),
                                      Buffer::Length(args[0])) != 1) {
     return env->ThrowError("Failed to fetch tls ticket keys");
   }
+#endif
 
   args.GetReturnValue().Set(true);
 #endif  // !def(OPENSSL_NO_TLSEXT) && def(SSL_CTX_get_tlsext_ticket_keys)
@@ -1427,6 +1452,42 @@ int SecureContext::TicketKeyCallback(SSL* ssl,
 }
 
 
+#if OPENSSL_VERSION_NUMBER >= 0x10100000L
+int SecureContext::TicketCompatibilityCallback(SSL* ssl,
+                                               unsigned char* name,
+                                               unsigned char* iv,
+                                               EVP_CIPHER_CTX* ectx,
+                                               HMAC_CTX* hctx,
+                                               int enc) {
+  SecureContext* sc = static_cast<SecureContext*>(
+      SSL_CTX_get_app_data(SSL_get_SSL_CTX(ssl)));
+
+  if (enc) {
+    memcpy(name, sc->ticket_key_name_, sizeof(sc->ticket_key_name_));
+    if (RAND_bytes(iv, 16) <= 0 ||
+        EVP_EncryptInit_ex(ectx, EVP_aes_128_cbc(), nullptr,
+                           sc->ticket_key_aes_, iv) <= 0 ||
+        HMAC_Init_ex(hctx, sc->ticket_key_hmac_, sizeof(sc->ticket_key_hmac_),
+                     EVP_sha256(), nullptr) <= 0) {
+      return -1;
+    }
+    return 1;
+  }
+
+  if (memcmp(name, sc->ticket_key_name_, sizeof(sc->ticket_key_name_)) != 0) {
+    // The ticket key name does not match. Discard the ticket.
+    return 0;
+  }
+
+  if (EVP_DecryptInit_ex(ectx, EVP_aes_128_cbc(), nullptr, sc->ticket_key_aes_,
+                         iv) <= 0 ||
+      HMAC_Init_ex(hctx, sc->ticket_key_hmac_, sizeof(sc->ticket_key_hmac_),
+                   EVP_sha256(), nullptr) <= 0) {
+    return -1;
+  }
+  return 1;
+}
+#endif
 
 
 void SecureContext::CtxGetter(Local<String> property,
diff --git a/src/node_crypto.h b/src/node_crypto.h
@@ -103,6 +103,12 @@ class SecureContext : public BaseObject {
   static const int kTicketKeyNameIndex = 3;
   static const int kTicketKeyIVIndex = 4;
 
+#if OPENSSL_VERSION_NUMBER >= 0x10100000L
+  unsigned char ticket_key_name_[16];
+  unsigned char ticket_key_aes_[16];
+  unsigned char ticket_key_hmac_[16];
+#endif
+
  protected:
 #if OPENSSL_VERSION_NUMBER < 0x10100000L
   static const int64_t kExternalSize = sizeof(SSL_CTX);
@@ -148,6 +154,15 @@ class SecureContext : public BaseObject {
                                HMAC_CTX* hctx,
                                int enc);
 
+#if OPENSSL_VERSION_NUMBER >= 0x10100000L
+  static int TicketCompatibilityCallback(SSL* ssl,
+                                         unsigned char* name,
+                                         unsigned char* iv,
+                                         EVP_CIPHER_CTX* ectx,
+                                         HMAC_CTX* hctx,
+                                         int enc);
+#endif
+
   SecureContext(Environment* env, v8::Local<v8::Object> wrap)
       : BaseObject(env, wrap),
         ctx_(nullptr),
