tls: expose SSL_export_keying_material

Fixes: #31802 PR-URL: #31814 Reviewed-By: Anna Henningsen <anna@addaleax.net> Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl> Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Tobias Nießen <tniessen@tnie.de>
nodejs · Apr 28, 2020 · 6348fae · 6348fae
1 parent 02de66a
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diff --git a/doc/api/errors.md b/doc/api/errors.md
@@ -1850,6 +1850,15 @@ added: v12.16.0
 
 The context must be a `SecureContext`.
 
+<a id="ERR_TLS_INVALID_STATE"></a>
+### `ERR_TLS_INVALID_STATE`
+<!-- YAML
+added: REPLACEME
+-->
+
+The TLS socket must be connected and securily established. Ensure the 'secure'
+event is emitted, before you continue.
+
 <a id="ERR_TLS_INVALID_PROTOCOL_METHOD"></a>
 ### `ERR_TLS_INVALID_PROTOCOL_METHOD`
 

diff --git a/doc/api/tls.md b/doc/api/tls.md
@@ -1094,6 +1094,39 @@ See
 [SSL_get_shared_sigalgs](https://www.openssl.org/docs/man1.1.1/man3/SSL_get_shared_sigalgs.html)
 for more information.
 
+### `tlsSocket.exportKeyingMaterial(length, label[, context])`
+<!-- YAML
+added: REPLACEME
+-->
+
+* `length` {number} number of bytes to retrieve from keying material
+* `label` {string} an application specific label, typically this will be a
+value from the
+[IANA Exporter Label Registry](https://www.iana.org/assignments/tls-parameters/tls-parameters.xhtml#exporter-labels).
+* `context` {Buffer} Optionally provide a context.
+
+* Returns: {Buffer} requested bytes of the keying material
+
+Keying material is used for validations to prevent different kind of attacks in
+network protocols, for example in the specifications of IEEE 802.1X.
+
+Example
+
+```js
+const keyingMaterial = tlsSocket.exportKeyingMaterial(
+  128,
+  'client finished');
+
+/**
+ Example return value of keyingMaterial:
+ <Buffer 76 26 af 99 c5 56 8e 42 09 91 ef 9f 93 cb ad 6c 7b 65 f8 53 f1 d8 d9
+    12 5a 33 b8 b5 25 df 7b 37 9f e0 e2 4f b8 67 83 a3 2f cd 5d 41 42 4c 91
+    74 ef 2c ... 78 more bytes>
+*/
+```
+See the OpenSSL [`SSL_export_keying_material`][] documentation for more
+information.
+
 ### `tlsSocket.getTLSTicket()`
 <!-- YAML
 added: v0.11.4
@@ -1899,6 +1932,7 @@ where `secureSocket` has the same API as `pair.cleartext`.
 [`'session'`]: #tls_event_session
 [`--tls-cipher-list`]: cli.html#cli_tls_cipher_list_list
 [`NODE_OPTIONS`]: cli.html#cli_node_options_options
+[`SSL_export_keying_material`]: https://www.openssl.org/docs/man1.1.1/man3/SSL_export_keying_material.html
 [`SSL_get_version`]: https://www.openssl.org/docs/man1.1.1/man3/SSL_get_version.html
 [`crypto.getCurves()`]: crypto.html#crypto_crypto_getcurves
 [`net.createServer()`]: net.html#net_net_createserver_options_connectionlistener

diff --git a/lib/_tls_wrap.js b/lib/_tls_wrap.js
@@ -65,11 +65,16 @@ const {
   ERR_TLS_RENEGOTIATION_DISABLED,
   ERR_TLS_REQUIRED_SERVER_NAME,
   ERR_TLS_SESSION_ATTACK,
-  ERR_TLS_SNI_FROM_SERVER
+  ERR_TLS_SNI_FROM_SERVER,
+  ERR_TLS_INVALID_STATE
 } = codes;
 const { onpskexchange: kOnPskExchange } = internalBinding('symbols');
 const { getOptionValue } = require('internal/options');
-const { validateString, validateBuffer } = require('internal/validators');
+const {
+  validateString,
+  validateBuffer,
+  validateUint32
+} = require('internal/validators');
 const traceTls = getOptionValue('--trace-tls');
 const tlsKeylog = getOptionValue('--tls-keylog');
 const { appendFile } = require('fs');
@@ -859,6 +864,18 @@ TLSSocket.prototype.renegotiate = function(options, callback) {
   return true;
 };
 
+TLSSocket.prototype.exportKeyingMaterial = function(length, label, context) {
+  validateUint32(length, 'length', true);
+  validateString(label, 'label');
+  if (context !== undefined)
+    validateBuffer(context, 'context');
+
+  if (!this._secureEstablished)
+    throw new ERR_TLS_INVALID_STATE();
+
+  return this._handle.exportKeyingMaterial(length, label, context);
+};
+
 TLSSocket.prototype.setMaxSendFragment = function setMaxSendFragment(size) {
   return this._handle.setMaxSendFragment(size) === 1;
 };

diff --git a/lib/internal/errors.js b/lib/internal/errors.js
@@ -1308,6 +1308,8 @@ E('ERR_TLS_CERT_ALTNAME_INVALID', function(reason, host, cert) {
 E('ERR_TLS_DH_PARAM_SIZE', 'DH parameter size %s is less than 2048', Error);
 E('ERR_TLS_HANDSHAKE_TIMEOUT', 'TLS handshake timeout', Error);
 E('ERR_TLS_INVALID_CONTEXT', '%s must be a SecureContext', TypeError),
+E('ERR_TLS_INVALID_STATE', 'TLS socket connection must be securely established',
+  Error),
 E('ERR_TLS_INVALID_PROTOCOL_VERSION',
   '%j is not a valid %s TLS protocol version', TypeError);
 E('ERR_TLS_PROTOCOL_VERSION_CONFLICT',

diff --git a/src/node_crypto.cc b/src/node_crypto.cc
@@ -1701,6 +1701,8 @@ void SSLWrap<Base>::AddMethods(Environment* env, Local<FunctionTemplate> t) {
   env->SetProtoMethodNoSideEffect(t, "verifyError", VerifyError);
   env->SetProtoMethodNoSideEffect(t, "getCipher", GetCipher);
   env->SetProtoMethodNoSideEffect(t, "getSharedSigalgs", GetSharedSigalgs);
+  env->SetProtoMethodNoSideEffect(
+      t, "exportKeyingMaterial", ExportKeyingMaterial);
   env->SetProtoMethod(t, "endParser", EndParser);
   env->SetProtoMethod(t, "certCbDone", CertCbDone);
   env->SetProtoMethod(t, "renegotiate", Renegotiate);
@@ -2216,6 +2218,44 @@ void SSLWrap<Base>::GetSharedSigalgs(const FunctionCallbackInfo<Value>& args) {
                  Array::New(env->isolate(), ret_arr.out(), ret_arr.length()));
 }
 
+template <class Base>
+void SSLWrap<Base>::ExportKeyingMaterial(
+    const FunctionCallbackInfo<Value>& args) {
+  CHECK(args[0]->IsInt32());
+  CHECK(args[1]->IsString());
+
+  Base* w;
+  ASSIGN_OR_RETURN_UNWRAP(&w, args.Holder());
+  Environment* env = w->ssl_env();
+
+  uint32_t olen = args[0].As<Uint32>()->Value();
+  node::Utf8Value label(env->isolate(), args[1]);
+
+  AllocatedBuffer out = env->AllocateManaged(olen);
+
+  ByteSource key;
+
+  int useContext = 0;
+  if (!args[2]->IsNull() && Buffer::HasInstance(args[2])) {
+    key = ByteSource::FromBuffer(args[2]);
+
+    useContext = 1;
+  }
+
+  if (SSL_export_keying_material(w->ssl_.get(),
+                                 reinterpret_cast<unsigned char*>(out.data()),
+                                 olen,
+                                 *label,
+                                 label.length(),
+                                 reinterpret_cast<const unsigned char*>(
+                                   key.get()),
+                                 key.size(),
+                                 useContext) != 1) {
+    return ThrowCryptoError(env, ERR_get_error(), "SSL_export_keying_material");
+  }
+
+  args.GetReturnValue().Set(out.ToBuffer().ToLocalChecked());
+}
 
 template <class Base>
 void SSLWrap<Base>::GetProtocol(const FunctionCallbackInfo<Value>& args) {

diff --git a/src/node_crypto.h b/src/node_crypto.h
@@ -251,6 +251,8 @@ class SSLWrap {
   static void VerifyError(const v8::FunctionCallbackInfo<v8::Value>& args);
   static void GetCipher(const v8::FunctionCallbackInfo<v8::Value>& args);
   static void GetSharedSigalgs(const v8::FunctionCallbackInfo<v8::Value>& args);
+  static void ExportKeyingMaterial(
+      const v8::FunctionCallbackInfo<v8::Value>& args);
   static void EndParser(const v8::FunctionCallbackInfo<v8::Value>& args);
   static void CertCbDone(const v8::FunctionCallbackInfo<v8::Value>& args);
   static void Renegotiate(const v8::FunctionCallbackInfo<v8::Value>& args);

diff --git a/test/parallel/test-tls-exportkeyingmaterial.js b/test/parallel/test-tls-exportkeyingmaterial.js
@@ -0,0 +1,102 @@
+'use strict';
+
+// Test return value of tlsSocket.exportKeyingMaterial
+
+const common = require('../common');
+
+if (!common.hasCrypto)
+  common.skip('missing crypto');
+
+const assert = require('assert');
+const net = require('net');
+const tls = require('tls');
+const fixtures = require('../common/fixtures');
+
+const key = fixtures.readKey('agent1-key.pem');
+const cert = fixtures.readKey('agent1-cert.pem');
+
+const server = net.createServer(common.mustCall((s) => {
+  const tlsSocket = new tls.TLSSocket(s, {
+    isServer: true,
+    server: server,
+    secureContext: tls.createSecureContext({ key, cert })
+  });
+
+  assert.throws(() => {
+    tlsSocket.exportKeyingMaterial(128, 'label');
+  }, {
+    name: 'Error',
+    message: 'TLS socket connection must be securely established',
+    code: 'ERR_TLS_INVALID_STATE'
+  });
+
+  tlsSocket.on('secure', common.mustCall(() => {
+    const label = 'client finished';
+
+    const validKeyingMaterial = tlsSocket.exportKeyingMaterial(128, label);
+    assert.strictEqual(validKeyingMaterial.length, 128);
+
+    const validKeyingMaterialWithContext = tlsSocket
+      .exportKeyingMaterial(128, label, Buffer.from([0, 1, 2, 3]));
+    assert.strictEqual(validKeyingMaterialWithContext.length, 128);
+
+    // Ensure providing a context results in a different key than without
+    assert.notStrictEqual(validKeyingMaterial, validKeyingMaterialWithContext);
+
+    const validKeyingMaterialWithEmptyContext = tlsSocket
+      .exportKeyingMaterial(128, label, Buffer.from([]));
+    assert.strictEqual(validKeyingMaterialWithEmptyContext.length, 128);
+
+    assert.throws(() => {
+      tlsSocket.exportKeyingMaterial(128, label, 'stringAsContextNotSupported');
+    }, {
+      name: 'TypeError',
+      code: 'ERR_INVALID_ARG_TYPE'
+    });
+
+    assert.throws(() => {
+      tlsSocket.exportKeyingMaterial(128, label, 1234);
+    }, {
+      name: 'TypeError',
+      code: 'ERR_INVALID_ARG_TYPE'
+    });
+
+    assert.throws(() => {
+      tlsSocket.exportKeyingMaterial(10, null);
+    }, {
+      name: 'TypeError',
+      code: 'ERR_INVALID_ARG_TYPE'
+    });
+
+    assert.throws(() => {
+      tlsSocket.exportKeyingMaterial('length', 1234);
+    }, {
+      name: 'TypeError',
+      code: 'ERR_INVALID_ARG_TYPE'
+    });
+
+    assert.throws(() => {
+      tlsSocket.exportKeyingMaterial(-3, 'a');
+    }, {
+      name: 'RangeError',
+      code: 'ERR_OUT_OF_RANGE'
+    });
+
+    assert.throws(() => {
+      tlsSocket.exportKeyingMaterial(0, 'a');
+    }, {
+      name: 'RangeError',
+      code: 'ERR_OUT_OF_RANGE'
+    });
+
+    tlsSocket.end();
+    server.close();
+  }));
+})).listen(0, () => {
+  const opts = {
+    port: server.address().port,
+    rejectUnauthorized: false
+  };
+
+  tls.connect(opts, common.mustCall(function() { this.end(); }));
+});