io: add QIOChannelTLS class

Add a QIOChannel subclass that can run the TLS protocol over
the top of another QIOChannel instance. The object provides a
simplified API to perform the handshake when starting the TLS
session. The layering of TLS over the underlying channel does
not have to be setup immediately. It is possible to take an
existing QIOChannel that has done some handshake and then swap
in the QIOChannelTLS layer. This allows for use with protocols
which start TLS right away, and those which start plain text
and then negotiate TLS.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>

include/io/channel-tls.h

@@ -0,0 +1,142 @@
+/*
+ * QEMU I/O channels TLS driver
+ *
+ * Copyright (c) 2015 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#ifndef QIO_CHANNEL_TLS_H__
+#define QIO_CHANNEL_TLS_H__
+
+#include "io/channel.h"
+#include "io/task.h"
+#include "crypto/tlssession.h"
+
+#define TYPE_QIO_CHANNEL_TLS "qio-channel-tls"
+#define QIO_CHANNEL_TLS(obj)                                     \
+    OBJECT_CHECK(QIOChannelTLS, (obj), TYPE_QIO_CHANNEL_TLS)
+
+typedef struct QIOChannelTLS QIOChannelTLS;
+
+/**
+ * QIOChannelTLS
+ *
+ * The QIOChannelTLS class provides a channel wrapper which
+ * can transparently run the TLS encryption protocol. It is
+ * usually used over a TCP socket, but there is actually no
+ * technical restriction on which type of master channel is
+ * used as the transport.
+ *
+ * This channel object is capable of running as either a
+ * TLS server or TLS client.
+ */
+
+struct QIOChannelTLS {
+    QIOChannel parent;
+    QIOChannel *master;
+    QCryptoTLSSession *session;
+};
+
+/**
+ * qio_channel_tls_new_server:
+ * @master: the underlying channel object
+ * @creds: the credentials to use for TLS handshake
+ * @aclname: the access control list for validating clients
+ * @errp: pointer to an uninitialized error object
+ *
+ * Create a new TLS channel that runs the server side of
+ * a TLS session. The TLS session handshake will use the
+ * credentials provided in @creds. If the @aclname parameter
+ * is non-NULL, then the client will have to provide
+ * credentials (ie a x509 client certificate) which will
+ * then be validated against the ACL.
+ *
+ * After creating the channel, it is mandatory to call
+ * the qio_channel_tls_handshake() method before attempting
+ * todo any I/O on the channel.
+ *
+ * Once the handshake has completed, all I/O should be done
+ * via the new TLS channel object and not the original
+ * master channel
+ *
+ * Returns: the new TLS channel object, or NULL
+ */
+QIOChannelTLS *
+qio_channel_tls_new_server(QIOChannel *master,
+                           QCryptoTLSCreds *creds,
+                           const char *aclname,
+                           Error **errp);
+
+/**
+ * qio_channel_tls_new_client:
+ * @master: the underlying channel object
+ * @creds: the credentials to use for TLS handshake
+ * @hostname: the user specified server hostname
+ * @errp: pointer to an uninitialized error object
+ *
+ * Create a new TLS channel that runs the client side of
+ * a TLS session. The TLS session handshake will use the
+ * credentials provided in @creds. The @hostname parameter
+ * should provide the user specified hostname of the server
+ * and will be validated against the server's credentials
+ * (ie CommonName of the x509 certificate)
+ *
+ * After creating the channel, it is mandatory to call
+ * the qio_channel_tls_handshake() method before attempting
+ * todo any I/O on the channel.
+ *
+ * Once the handshake has completed, all I/O should be done
+ * via the new TLS channel object and not the original
+ * master channel
+ *
+ * Returns: the new TLS channel object, or NULL
+ */
+QIOChannelTLS *
+qio_channel_tls_new_client(QIOChannel *master,
+                           QCryptoTLSCreds *creds,
+                           const char *hostname,
+                           Error **errp);
+
+/**
+ * qio_channel_tls_handshake:
+ * @ioc: the TLS channel object
+ * @func: the callback to invoke when completed
+ * @opaque: opaque data to pass to @func
+ * @destroy: optional callback to free @opaque
+ *
+ * Perform the TLS session handshake. This method
+ * will return immediately and the handshake will
+ * continue in the background, provided the main
+ * loop is running. When the handshake is complete,
+ * or fails, the @func callback will be invoked.
+ */
+void qio_channel_tls_handshake(QIOChannelTLS *ioc,
+                               QIOTaskFunc func,
+                               gpointer opaque,
+                               GDestroyNotify destroy);
+
+/**
+ * qio_channel_tls_get_session:
+ * @ioc: the TLS channel object
+ *
+ * Get the TLS session used by the channel.
+ *
+ * Returns: the TLS session
+ */
+QCryptoTLSSession *
+qio_channel_tls_get_session(QIOChannelTLS *ioc);
+
+#endif /* QIO_CHANNEL_TLS_H__ */

io/Makefile.objs

@@ -1,5 +1,6 @@
 io-obj-y = channel.o
 io-obj-y += channel-file.o
 io-obj-y += channel-socket.o
+io-obj-y += channel-tls.o
 io-obj-y += channel-watch.o
 io-obj-y += task.o