tls: add PSK support

Add the `pskCallback` client/server option, which resolves an identity
or identity hint to a pre-shared key.

Add the `pskIdentityHint` server option to set the identity hint for the
ServerKeyExchange message.

Co-authored-by: Chris Osborn <chris.osborn@sitelier.com>
Co-authored-by: stephank <gh@stephank.nl>
Co-authored-by: Taylor Zane Glaeser <tzglaeser@gmail.com>

PR-URL: https://github.com/nodejs/node/pull/23188
Reviewed-By: Sam Roberts <vieuxtech@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>

1 files changed, 114 insertions, 3 deletions

diff --git a/lib/_tls_wrap.js b/lib/_tls_wrap.js
index 02a5074b4fe..47a59c02fc5 100644
--- a/lib/_tls_wrap.js
+++ b/lib/_tls_wrap.js
@@ -50,10 +50,12 @@ const { TCP, constants: TCPConstants } = internalBinding('tcp_wrap');
 const tls_wrap = internalBinding('tls_wrap');
 const { Pipe, constants: PipeConstants } = internalBinding('pipe_wrap');
 const { owner_symbol } = require('internal/async_hooks').symbols;
+const { isArrayBufferView } = require('internal/util/types');
 const { SecureContext: NativeSecureContext } = internalBinding('crypto');
 const { connResetException, codes } = require('internal/errors');
 const {
   ERR_INVALID_ARG_TYPE,
+  ERR_INVALID_ARG_VALUE,
   ERR_INVALID_CALLBACK,
   ERR_MULTIPLE_CALLBACK,
   ERR_SOCKET_CLOSED,
@@ -65,8 +67,9 @@ const {
   ERR_TLS_SESSION_ATTACK,
   ERR_TLS_SNI_FROM_SERVER
 } = codes;
+const { onpskexchange: kOnPskExchange } = internalBinding('symbols');
 const { getOptionValue } = require('internal/options');
-const { validateString } = require('internal/validators');
+const { validateString, validateBuffer } = require('internal/validators');
 const traceTls = getOptionValue('--trace-tls');
 const tlsKeylog = getOptionValue('--tls-keylog');
 const { appendFile } = require('fs');
@@ -77,6 +80,8 @@ const kHandshakeTimeout = Symbol('handshake-timeout');
 const kRes = Symbol('res');
 const kSNICallback = Symbol('snicallback');
 const kEnableTrace = Symbol('enableTrace');
+const kPskCallback = Symbol('pskcallback');
+const kPskIdentityHint = Symbol('pskidentityhint');
 
 const noop = () => {};
 
@@ -296,6 +301,67 @@ function onnewsession(sessionId, session) {
     done();
 }
 
+function onPskServerCallback(identity, maxPskLen) {
+  const owner = this[owner_symbol];
+  const ret = owner[kPskCallback](owner, identity);
+  if (ret == null)
+    return undefined;
+
+  let psk;
+  if (isArrayBufferView(ret)) {
+    psk = ret;
+  } else {
+    if (typeof ret !== 'object') {
+      throw new ERR_INVALID_ARG_TYPE(
+        'ret',
+        ['Object', 'Buffer', 'TypedArray', 'DataView'],
+        ret
+      );
+    }
+    psk = ret.psk;
+    validateBuffer(psk, 'psk');
+  }
+
+  if (psk.length > maxPskLen) {
+    throw new ERR_INVALID_ARG_VALUE(
+      'psk',
+      psk,
+      `Pre-shared key exceeds ${maxPskLen} bytes`
+    );
+  }
+
+  return psk;
+}
+
+function onPskClientCallback(hint, maxPskLen, maxIdentityLen) {
+  const owner = this[owner_symbol];
+  const ret = owner[kPskCallback](hint);
+  if (ret == null)
+    return undefined;
+
+  if (typeof ret !== 'object')
+    throw new ERR_INVALID_ARG_TYPE('ret', 'Object', ret);
+
+  validateBuffer(ret.psk, 'psk');
+  if (ret.psk.length > maxPskLen) {
+    throw new ERR_INVALID_ARG_VALUE(
+      'psk',
+      ret.psk,
+      `Pre-shared key exceeds ${maxPskLen} bytes`
+    );
+  }
+
+  validateString(ret.identity, 'identity');
+  if (Buffer.byteLength(ret.identity) > maxIdentityLen) {
+    throw new ERR_INVALID_ARG_VALUE(
+      'identity',
+      ret.identity,
+      `PSK identity exceeds ${maxIdentityLen} bytes`
+    );
+  }
+
+  return { psk: ret.psk, identity: ret.identity };
+}
 
 function onkeylogclient(line) {
   debug('client onkeylog');
@@ -694,6 +760,32 @@ TLSSocket.prototype._init = function(socket, wrap) {
     ssl.setALPNProtocols(ssl._secureContext.alpnBuffer);
   }
 
+  if (options.pskCallback && ssl.enablePskCallback) {
+    if (typeof options.pskCallback !== 'function') {
+      throw new ERR_INVALID_ARG_TYPE('pskCallback',
+                                     'function',
+                                     options.pskCallback);
+    }
+
+    ssl[kOnPskExchange] = options.isServer ?
+      onPskServerCallback : onPskClientCallback;
+
+    this[kPskCallback] = options.pskCallback;
+    ssl.enablePskCallback();
+
+    if (options.pskIdentityHint) {
+      if (typeof options.pskIdentityHint !== 'string') {
+        throw new ERR_INVALID_ARG_TYPE(
+          'options.pskIdentityHint',
+          'string',
+          options.pskIdentityHint
+        );
+      }
+      ssl.setPskIdentityHint(options.pskIdentityHint);
+    }
+  }
+
+
   if (options.handshakeTimeout > 0)
     this.setTimeout(options.handshakeTimeout, this._handleTimeout);
 
@@ -905,7 +997,7 @@ function makeSocketMethodProxy(name) {
   TLSSocket.prototype[method] = makeSocketMethodProxy(method);
 });
 
-// TODO: support anonymous (nocert) and PSK
+// TODO: support anonymous (nocert)
 
 
 function onServerSocketSecure() {
@@ -961,6 +1053,8 @@ function tlsConnectionListener(rawSocket) {
     SNICallback: this[kSNICallback] || SNICallback,
     enableTrace: this[kEnableTrace],
     pauseOnConnect: this.pauseOnConnect,
+    pskCallback: this[kPskCallback],
+    pskIdentityHint: this[kPskIdentityHint],
   });
 
   socket.on('secure', onServerSocketSecure);
@@ -1065,6 +1159,8 @@ function Server(options, listener) {
 
   this[kHandshakeTimeout] = options.handshakeTimeout || (120 * 1000);
   this[kSNICallback] = options.SNICallback;
+  this[kPskCallback] = options.pskCallback;
+  this[kPskIdentityHint] = options.pskIdentityHint;
 
   if (typeof this[kHandshakeTimeout] !== 'number') {
     throw new ERR_INVALID_ARG_TYPE(
@@ -1076,6 +1172,18 @@ function Server(options, listener) {
       'options.SNICallback', 'function', options.SNICallback);
   }
 
+  if (this[kPskCallback] && typeof this[kPskCallback] !== 'function') {
+    throw new ERR_INVALID_ARG_TYPE(
+      'options.pskCallback', 'function', options.pskCallback);
+  }
+  if (this[kPskIdentityHint] && typeof this[kPskIdentityHint] !== 'string') {
+    throw new ERR_INVALID_ARG_TYPE(
+      'options.pskIdentityHint',
+      'string',
+      options.pskIdentityHint
+    );
+  }
+
   // constructor call
   net.Server.call(this, options, tlsConnectionListener);
 
@@ -1272,6 +1380,8 @@ Server.prototype.setOptions = deprecate(function(options) {
                                   .digest('hex')
                                   .slice(0, 32);
   }
+  if (options.pskCallback) this[kPskCallback] = options.pskCallback;
+  if (options.pskIdentityHint) this[kPskIdentityHint] = options.pskIdentityHint;
 }, 'Server.prototype.setOptions() is deprecated', 'DEP0122');
 
 // SNI Contexts High-Level API
@@ -1459,7 +1569,8 @@ exports.connect = function connect(...args) {
     session: options.session,
     ALPNProtocols: options.ALPNProtocols,
     requestOCSP: options.requestOCSP,
-    enableTrace: options.enableTrace
+    enableTrace: options.enableTrace,
+    pskCallback: options.pskCallback,
   });
 
   tlssock[kConnectOptions] = options;