Support for client certs in ssl_server_socket.

net/socket/ssl_server_socket_openssl.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/socket/ssl_server_socket_openssl.h"
 
 #include <openssl/err.h>
 #include <openssl/ssl.h>
 
 #include "base/callback_helpers.h"
 #include "base/logging.h"
 #include "base/strings/string_util.h"
 #include "crypto/openssl_util.h"
 #include "crypto/rsa_private_key.h"
 #include "crypto/scoped_openssl_types.h"
 #include "net/base/net_errors.h"
+#include "net/cert/cert_verify_result.h"
+#include "net/cert/client_cert_verifier.h"
+#include "net/cert/x509_util_openssl.h"
 #include "net/ssl/openssl_ssl_util.h"
 #include "net/ssl/scoped_openssl_types.h"
+#include "net/ssl/ssl_connection_status_flags.h"
+#include "net/ssl/ssl_info.h"
 
 #define GotoState(s) next_handshake_state_ = s
 
 namespace net {
 
+namespace {
+
+scoped_refptr<X509Certificate> CreateX509Certificate(X509* cert,
+                                                     STACK_OF(X509) * chain) {
+  std::vector<base::StringPiece> der_chain;
+  base::StringPiece der_cert;
+  scoped_refptr<X509Certificate> client_cert;
+  if (cert) {
+    if (!x509_util::GetDER(cert, &der_cert))
+      return client_cert;
+    der_chain.push_back(der_cert);
+  }
+
+  ScopedX509_STACK openssl_chain(X509_chain_up_ref(chain));
+  for (size_t i = 0; i < sk_X509_num(openssl_chain.get()); ++i) {
+    X509* x = sk_X509_value(openssl_chain.get(), i);
+    if (x509_util::GetDER(x, &der_cert)) {
+      der_chain.push_back(der_cert);
+    } else {
+      return nullptr;
+    }
+  }
+
+  return X509Certificate::CreateFromDERCertChain(der_chain);
+}
+
+}  // namespace
+
 void EnableSSLServerSockets() {
   // No-op because CreateSSLServerSocket() calls crypto::EnsureOpenSSLInit().
 }
 
 scoped_ptr<SSLServerSocket> CreateSSLServerSocket(
     scoped_ptr<StreamSocket> socket,
     X509Certificate* certificate,
     crypto::RSAPrivateKey* key,
-    const SSLServerConfig& ssl_config) {
+    const SSLServerConfig& ssl_server_config) {
   crypto::EnsureOpenSSLInit();
-  return scoped_ptr<SSLServerSocket>(
-      new SSLServerSocketOpenSSL(socket.Pass(), certificate, key, ssl_config));
+  return scoped_ptr<SSLServerSocket>(new SSLServerSocketOpenSSL(
+      socket.Pass(), certificate, key, ssl_server_config));
 }
 
 SSLServerSocketOpenSSL::SSLServerSocketOpenSSL(
     scoped_ptr<StreamSocket> transport_socket,
     scoped_refptr<X509Certificate> certificate,
     crypto::RSAPrivateKey* key,
-    const SSLServerConfig& ssl_config)
+    const SSLServerConfig& ssl_server_config)
     : transport_send_busy_(false),
       transport_recv_busy_(false),
       transport_recv_eof_(false),
       user_read_buf_len_(0),
       user_write_buf_len_(0),
       transport_write_error_(OK),
       ssl_(NULL),
       transport_bio_(NULL),
       transport_socket_(transport_socket.Pass()),
-      ssl_config_(ssl_config),
+      ssl_server_config_(ssl_server_config),
       cert_(certificate),
       next_handshake_state_(STATE_NONE),
       completed_handshake_(false) {
   // TODO(byungchul): Need a better way to clone a key.
   std::vector<uint8> key_bytes;
   CHECK(key->ExportPrivateKey(&key_bytes));
   key_.reset(crypto::RSAPrivateKey::CreateFromPrivateKeyInfo(key_bytes));
   CHECK(key_.get());
 }
 
@@ skipping 173 matching lines @@
 bool SSLServerSocketOpenSSL::WasNpnNegotiated() const {
   NOTIMPLEMENTED();
   return false;
 }
 
 NextProto SSLServerSocketOpenSSL::GetNegotiatedProtocol() const {
   // NPN is not supported by this class.
   return kProtoUnknown;
 }
 
 bool SSLServerSocketOpenSSL::GetSSLInfo(SSLInfo* ssl_info) {

[Ryan Sleevi, 2015/12/17 03:47:36]

I'm pretty sure this is just a wrong interface for server sockets. It doesn't
make sense when so much of SSLInfo is client-socket specific.

[ryanchung, 2015/12/18 00:00:55]

Should this be in a new interface like GetSSLServerInfo(SSLServerInfo*) where
SSLServerInfo only has the server related info?

-  NOTIMPLEMENTED();
-  return false;
+  ssl_info->Reset();
+  if (!completed_handshake_) {
+    return false;
+  }

[Ryan Sleevi, 2015/12/17 03:47:35]

nit: We don't do braces for one-line if's in //net
nit 2: Extra newline between return false and ExtractClientCert

[ryanchung, 2015/12/18 00:00:55]

Done.

+  ExtractClientCert();
+  ssl_info->cert = client_cert_;
+
+  const SSL_CIPHER* cipher = SSL_get_current_cipher(ssl_);
+  CHECK(cipher);
+  ssl_info->security_bits = SSL_CIPHER_get_bits(cipher, NULL);
+
+  SSLConnectionStatusSetCipherSuite(
+      static_cast<uint16>(SSL_CIPHER_get_id(cipher)),
+      &ssl_info->connection_status);
+  SSLConnectionStatusSetVersion(GetNetSSLVersion(ssl_),
+                                &ssl_info->connection_status);
+
+  if (!SSL_get_secure_renegotiation_support(ssl_))
+    ssl_info->connection_status |= SSL_CONNECTION_NO_RENEGOTIATION_EXTENSION;
+
+  ssl_info->handshake_type = SSL_session_reused(ssl_)
+                                 ? SSLInfo::HANDSHAKE_RESUME
+                                 : SSLInfo::HANDSHAKE_FULL;
+
+  return true;
 }
 
 void SSLServerSocketOpenSSL::GetConnectionAttempts(
     ConnectionAttempts* out) const {
   out->clear();
 }
 
 int64_t SSLServerSocketOpenSSL::GetTotalReceivedBytes() const {
   return transport_socket_->GetTotalReceivedBytes();
 }
@@ skipping 302 matching lines @@
   return rv;
 }
 
 int SSLServerSocketOpenSSL::DoHandshake() {
   crypto::OpenSSLErrStackTracer err_tracer(FROM_HERE);
   int net_error = OK;
   int rv = SSL_do_handshake(ssl_);
 
   if (rv == 1) {
     completed_handshake_ = true;
+    ExtractClientCert();

[Ryan Sleevi, 2015/12/17 03:47:35]

This feels weird, in that it leaves multiple places for client_cert_ to be
assigned. Why is that? I would logically expect it to just happen in the
handshake.

[ryanchung, 2015/12/18 00:00:55]

This was supposed to be the only place this is called. I missed removing the
call in GetSSLInfo(). Sorry.

   } else {
     int ssl_error = SSL_get_error(ssl_, rv);
     OpenSSLErrorInfo error_info;
     net_error = MapOpenSSLErrorWithDetails(ssl_error, err_tracer, &error_info);
 
+    // This hack is necessary because the mapping of SSL error codes to
+    // net_errors assumes (correctly for client sockets, but erroneously for
+    // server sockets) that peer cert verification failure can only occur if
+    // the cert changed during a renego. crbug.com/570351
+    if (net_error == ERR_SSL_SERVER_CERT_CHANGED)
+      net_error = ERR_BAD_SSL_CLIENT_AUTH_CERT;
+
     // If not done, stay in this state
     if (net_error == ERR_IO_PENDING) {
       GotoState(STATE_HANDSHAKE);
     } else {
       LOG(ERROR) << "handshake failed; returned " << rv
                  << ", SSL error code " << ssl_error
                  << ", net_error " << net_error;
       net_log_.AddEvent(
           NetLog::TYPE_SSL_HANDSHAKE_ERROR,
           CreateNetLogOpenSSLErrorCallback(net_error, ssl_error, error_info));
@@ skipping 25 matching lines @@
   ResetAndReturn(&user_write_callback_).Run(rv);
 }
 
 int SSLServerSocketOpenSSL::Init() {
   DCHECK(!ssl_);
   DCHECK(!transport_bio_);
 
   crypto::OpenSSLErrStackTracer err_tracer(FROM_HERE);
 
   ScopedSSL_CTX ssl_ctx(SSL_CTX_new(SSLv23_server_method()));
-
-  if (ssl_config_.require_client_cert)
-    SSL_CTX_set_verify(ssl_ctx.get(), SSL_VERIFY_PEER, NULL);
-
+  if (ssl_server_config_.require_client_cert)
+    SSL_CTX_set_verify(ssl_ctx.get(),
+                       SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT, NULL);

[Ryan Sleevi, 2015/12/17 03:47:36]

Ironically, you should use braces here, even though it's multi-line in the
parenthesis.

[ryanchung, 2015/12/18 00:00:55]

Done.

+  SSL_CTX_set_cert_verify_callback(ssl_ctx.get(), CertVerifyCallback,
+                                   ssl_server_config_.client_cert_verifier);
   ssl_ = SSL_new(ssl_ctx.get());
   if (!ssl_)
     return ERR_UNEXPECTED;
 
   BIO* ssl_bio = NULL;
   // 0 => use default buffer sizes.
   if (!BIO_new_bio_pair(&ssl_bio, 0, &transport_bio_, 0))
     return ERR_UNEXPECTED;
   DCHECK(ssl_bio);
   DCHECK(transport_bio_);
@@ skipping 26 matching lines @@
     return ERR_UNEXPECTED;
   }
 #endif  // USE_OPENSSL_CERTS
 
   DCHECK(key_->key());
   if (SSL_use_PrivateKey(ssl_, key_->key()) != 1) {
     LOG(ERROR) << "Cannot set private key.";
     return ERR_UNEXPECTED;
   }
 
-  DCHECK_LT(SSL3_VERSION, ssl_config_.version_min);
-  DCHECK_LT(SSL3_VERSION, ssl_config_.version_max);
-  SSL_set_min_version(ssl_, ssl_config_.version_min);
-  SSL_set_max_version(ssl_, ssl_config_.version_max);
+  DCHECK_LT(SSL3_VERSION, ssl_server_config_.version_min);
+  DCHECK_LT(SSL3_VERSION, ssl_server_config_.version_max);
+  SSL_set_min_version(ssl_, ssl_server_config_.version_min);
+  SSL_set_max_version(ssl_, ssl_server_config_.version_max);
 
   // OpenSSL defaults some options to on, others to off. To avoid ambiguity,
   // set everything we care about to an absolute value.
   SslSetClearMask options;
   options.ConfigureFlag(SSL_OP_NO_COMPRESSION, true);
 
   SSL_set_options(ssl_, options.set_mask);
   SSL_clear_options(ssl_, options.clear_mask);
 
   // Same as above, this time for the SSL mode.
   SslSetClearMask mode;
 
   mode.ConfigureFlag(SSL_MODE_RELEASE_BUFFERS, true);
 
   SSL_set_mode(ssl_, mode.set_mask);
   SSL_clear_mode(ssl_, mode.clear_mask);
 
   // See SSLServerConfig::disabled_cipher_suites for description of the suites
   // disabled by default. Note that !SHA256 and !SHA384 only remove HMAC-SHA256
   // and HMAC-SHA384 cipher suites, not GCM cipher suites with SHA256 or SHA384
   // as the handshake hash.
   std::string command("DEFAULT:!SHA256:!SHA384:!AESGCM+AES256:!aPSK");
 
-  if (ssl_config_.require_ecdhe)
+  if (ssl_server_config_.require_ecdhe)
     command.append(":!kRSA:!kDHE");
 
   // Remove any disabled ciphers.
-  for (uint16_t id : ssl_config_.disabled_cipher_suites) {
+  for (uint16_t id : ssl_server_config_.disabled_cipher_suites) {
     const SSL_CIPHER* cipher = SSL_get_cipher_by_value(id);
     if (cipher) {
       command.append(":!");
       command.append(SSL_CIPHER_get_name(cipher));
     }
   }
 
   int rv = SSL_set_cipher_list(ssl_, command.c_str());
   // If this fails (rv = 0) it means there are no ciphers enabled on this SSL.
   // This will almost certainly result in the socket failing to complete the
   // handshake at which point the appropriate error is bubbled up to the client.
   LOG_IF(WARNING, rv != 1) << "SSL_set_cipher_list('" << command
                            << "') returned " << rv;
 
+  if (ssl_server_config_.require_client_cert) {
+    if (!ssl_server_config_.client_cert_ca_list.empty()) {

[Ryan Sleevi, 2015/12/17 03:47:36]

Could you combine these two conditionals?

[ryanchung, 2015/12/18 00:00:55]

Done.

+      ScopedX509_NAME_STACK stack(sk_X509_NAME_new_null());
+      for (const auto& certificate : ssl_server_config_.client_cert_ca_list) {
+        ScopedX509 ca_cert =
+            OSCertHandleToOpenSSL(certificate->os_cert_handle());
+        ScopedX509_NAME subj(X509_NAME_dup(ca_cert->cert_info->subject));
+        sk_X509_NAME_push(stack.get(), subj.release());
+      }
+      SSL_set_client_CA_list(ssl_, stack.release());
+    }
+  }
+
   return OK;
 }
 
+void SSLServerSocketOpenSSL::ExtractClientCert() {
+  X509* cert = SSL_get_peer_certificate(ssl_);
+  STACK_OF(X509)* chain = SSL_get_peer_cert_chain(ssl_);
+  client_cert_ = CreateX509Certificate(cert, chain);
+}

[Ryan Sleevi, 2015/12/17 03:47:36]

This feels like a weird API contract; why not just do something like

namespace {
scoped_refptr<X509Certificate> GetClientCert(SSL* ssl) {
 ...
}
}

and in DoHandshake something like

client_cert_ = GetClientCert(ssl_)

[ryanchung, 2015/12/18 00:00:55]

Done.

+
+// static
+int SSLServerSocketOpenSSL::CertVerifyCallback(X509_STORE_CTX* store_ctx,
+                                               void* arg) {
+  ClientCertVerifier* verifier = reinterpret_cast<ClientCertVerifier*>(arg);
+  // If a verifier was not supplied, all certificates are accepted.
+  if (!verifier)
+    return 1;
+  SSL* ssl = reinterpret_cast<SSL*>(X509_STORE_CTX_get_ex_data(
+      store_ctx, SSL_get_ex_data_X509_STORE_CTX_idx()));
+  DCHECK(ssl);
+  STACK_OF(X509)* chain = store_ctx->untrusted;
+  scoped_refptr<X509Certificate> client_cert(
+      CreateX509Certificate(nullptr, chain));
+
+  int res = verifier->Verify(client_cert.get());
+  if (res == OK) {

[Ryan Sleevi, 2015/12/17 03:47:36]

DESIGN: Please handle errors first, which will reduce indentation

if (res != OK) {
  X509_STORE_CTX_set_error(...);
  return 0;
}

return 1;

[ryanchung, 2015/12/18 00:00:55]

Done.

+    return 1;
+  } else {
+    X509_STORE_CTX_set_error(store_ctx, X509_V_ERR_CERT_REJECTED);
+    return 0;
+  }
+}
+
 }  // namespace net