crypto: allow adding extra certs to well-known CAs

In closed environments, self-signed or privately signed certificates are
commonly used, and rejected by Node.js since their root CAs are not
well-known. Allow extending the set of well-known compiled-in CAs via
environment, so they can be set as a matter of policy.

PR-URL: #9139
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Fedor Indutny <fedor.indutny@gmail.com>

doc/api/cli.md

@@ -315,7 +315,18 @@ asynchronous when outputting to a TTY on platforms which support async stdio.
 Setting this will void any guarantee that stdio will not be interleaved or
 dropped at program exit. **Use of this mode is not recommended.**
 
+### `NODE_EXTRA_CA_CERTS=file`
 
+When set, the well known "root" CAs (like VeriSign) will be extended with the
+extra certificates in `file`. The file should consist of one or more trusted
+certificates in PEM format. A message will be emitted (once) with
+[`process.emitWarning()`][emit_warning] if the file is missing or
+misformatted, but any errors are otherwise ignored.
+
+Note that neither the well known nor extra certificates are used when the `ca`
+options property is explicitly specified for a TLS or HTTPS client or server.
+
+[emit_warning]: process.html#process_process_emitwarning_warning_name_ctor
 [Buffer]: buffer.html#buffer_buffer
 [debugger]: debugger.html
 [REPL]: repl.html

src/node.cc

@@ -4535,6 +4535,8 @@ int Start(int argc, char** argv) {
   Init(&argc, const_cast<const char**>(argv), &exec_argc, &exec_argv);
 
 #if HAVE_OPENSSL
+  if (const char* extra = secure_getenv("NODE_EXTRA_CA_CERTS"))
+    crypto::UseExtraCaCerts(extra);
 #ifdef NODE_FIPS_MODE
   // In the case of FIPS builds we should make sure
   // the random source is properly initialized first.

src/node_crypto.cc

@@ -120,6 +120,8 @@ const char* const root_certs[] = {
 #include "node_root_certs.h"  // NOLINT(build/include_order)
 };
 
+std::string extra_root_certs_file;  // NOLINT(runtime/string)
+
 X509_STORE* root_cert_store;
 std::vector<X509*>* root_certs_vector;
 
@@ -789,6 +791,39 @@ void SecureContext::AddCRL(const FunctionCallbackInfo<Value>& args) {
 }
 
 
+void UseExtraCaCerts(const std::string& file) {
+  extra_root_certs_file = file;
+}
+
+
+static unsigned long AddCertsFromFile(  // NOLINT(runtime/int)
+    X509_STORE* store,
+    const char* file) {
+  ERR_clear_error();
+  MarkPopErrorOnReturn mark_pop_error_on_return;
+
+  BIO* bio = BIO_new_file(file, "r");
+  if (!bio) {
+    return ERR_get_error();
+  }
+
+  while (X509* x509 =
+      PEM_read_bio_X509(bio, nullptr, CryptoPemCallback, nullptr)) {
+    X509_STORE_add_cert(store, x509);
+    X509_free(x509);
+  }
+  BIO_free_all(bio);
+
+  unsigned long err = ERR_peek_error();  // NOLINT(runtime/int)
+  // Ignore error if its EOF/no start line found.
+  if (ERR_GET_LIB(err) == ERR_LIB_PEM &&
+      ERR_GET_REASON(err) == PEM_R_NO_START_LINE) {
+    return 0;
+  }
+
+  return err;
+}
+
 void SecureContext::AddRootCerts(const FunctionCallbackInfo<Value>& args) {
   SecureContext* sc;
   ASSIGN_OR_RETURN_UNWRAP(&sc, args.Holder());
@@ -797,6 +832,18 @@ void SecureContext::AddRootCerts(const FunctionCallbackInfo<Value>& args) {
 
   if (!root_cert_store) {
     root_cert_store = NewRootCertStore();
+
+    if (!extra_root_certs_file.empty()) {
+      unsigned long err = AddCertsFromFile(  // NOLINT(runtime/int)
+                                           root_cert_store,
+                                           extra_root_certs_file.c_str());
+      if (err) {
+        ProcessEmitWarning(sc->env(),
+                           "Ignoring extra certs from `%s`, load failed: %s\n",
+                           extra_root_certs_file.c_str(),
+                           ERR_error_string(err, nullptr));
+      }
+    }
   }
 
   // Increment reference count so global store is not deleted along with CTX.

src/node_crypto.h

@@ -65,6 +65,8 @@ extern int VerifyCallback(int preverify_ok, X509_STORE_CTX* ctx);
 
 extern X509_STORE* root_cert_store;
 
+extern void UseExtraCaCerts(const std::string& file);
+
 // Forward declaration
 class Connection;
 

test/parallel/test-tls-env-bad-extra-ca.js

@@ -0,0 +1,43 @@
+// Setting NODE_EXTRA_CA_CERTS to non-existent file emits a warning
+
+'use strict';
+const common = require('../common');
+
+if (!common.hasCrypto) {
+  common.skip('missing crypto');
+  return;
+}
+
+const assert = require('assert');
+const tls = require('tls');
+const fork = require('child_process').fork;
+
+if (process.env.CHILD) {
+  // This will try to load the extra CA certs, and emit a warning when it fails.
+  return tls.createServer({});
+}
+
+const env = {
+  CHILD: 'yes',
+  NODE_EXTRA_CA_CERTS: common.fixturesDir + '/no-such-file-exists',
+};
+
+var opts = {
+  env: env,
+  silent: true,
+};
+var stderr = '';
+
+fork(__filename, opts)
+  .on('exit', common.mustCall(function(status) {
+    assert.equal(status, 0, 'client did not succeed in connecting');
+  }))
+  .on('close', common.mustCall(function() {
+    assert(stderr.match(new RegExp(
+      'Warning: Ignoring extra certs from.*no-such-file-exists' +
+      '.* load failed:.*No such file or directory'
+    )), stderr);
+  }))
+  .stderr.setEncoding('utf8').on('data', function(str) {
+    stderr += str;
+  });

test/parallel/test-tls-env-extra-ca.js

@@ -0,0 +1,45 @@
+// Certs in NODE_EXTRA_CA_CERTS are used for TLS peer validation
+
+'use strict';
+const common = require('../common');
+
+if (!common.hasCrypto) {
+  common.skip('missing crypto');
+  return;
+}
+
+const assert = require('assert');
+const tls = require('tls');
+const fork = require('child_process').fork;
+const fs = require('fs');
+
+if (process.env.CHILD) {
+  const copts = {
+    port: process.env.PORT,
+    checkServerIdentity: function() {},
+  };
+  const client = tls.connect(copts, function() {
+    client.end('hi');
+  });
+  return;
+}
+
+const options = {
+  key: fs.readFileSync(common.fixturesDir + '/keys/agent1-key.pem'),
+  cert: fs.readFileSync(common.fixturesDir + '/keys/agent1-cert.pem'),
+};
+
+const server = tls.createServer(options, function(s) {
+  s.end('bye');
+  server.close();
+}).listen(0, common.mustCall(function() {
+  const env = {
+    CHILD: 'yes',
+    PORT: this.address().port,
+    NODE_EXTRA_CA_CERTS: common.fixturesDir + '/keys/ca1-cert.pem',
+  };
+
+  fork(__filename, {env: env}).on('exit', common.mustCall(function(status) {
+    assert.equal(status, 0, 'client did not succeed in connecting');
+  }));
+}));