crypto: Implement TLS Pre-Shared Keys (PSK).

Pre-Shared Keys (PSK) is a simpler mechanism for enabling TLS
connections than using certificates.  It requires only a simple secret
key:

  $ mkdir -m 0700 /tmp/keys
  $ psktool -u rjones -p /tmp/keys/keys.psk
  $ cat /tmp/keys/keys.psk
  rjones:d543770c15ad93d76443fb56f501a31969235f47e999720ae8d2336f6a13fcbc

The key can be secretly shared between clients and servers.  Clients
must specify the directory containing the "keys.psk" file and a
username (defaults to "qemu").  Servers must specify only the
directory.

Example NBD client:

  $ qemu-img info \
    --object tls-creds-psk,id=tls0,dir=/tmp/keys,username=rjones,endpoint=client \
    --image-opts \
    file.driver=nbd,file.host=localhost,file.port=10809,file.tls-creds=tls0,file.export=/

Example NBD server using qemu-nbd:

  $ qemu-nbd -t -x / \
    --object tls-creds-psk,id=tls0,endpoint=server,dir=/tmp/keys \
    --tls-creds tls0 \
    image.qcow2

Example NBD server using nbdkit:

  $ nbdkit -n -e / -fv \
    --tls=on --tls-psk=/tmp/keys/keys.psk \
    file file=disk.img

Signed-off-by: Richard W.M. Jones <rjones@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

1 files changed, 106 insertions, 0 deletions

diff --git a/include/crypto/tlscredspsk.h b/include/crypto/tlscredspsk.h
new file mode 100644
index 0000000000..306d36c67d
--- /dev/null
+++ b/include/crypto/tlscredspsk.h
@@ -0,0 +1,106 @@
+/*
+ * QEMU crypto TLS Pre-Shared Key (PSK) support
+ *
+ * Copyright (c) 2018 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 QCRYPTO_TLSCREDSPSK_H
+#define QCRYPTO_TLSCREDSPSK_H
+
+#include "crypto/tlscreds.h"
+
+#define TYPE_QCRYPTO_TLS_CREDS_PSK "tls-creds-psk"
+#define QCRYPTO_TLS_CREDS_PSK(obj)                  \
+    OBJECT_CHECK(QCryptoTLSCredsPSK, (obj), TYPE_QCRYPTO_TLS_CREDS_PSK)
+
+typedef struct QCryptoTLSCredsPSK QCryptoTLSCredsPSK;
+typedef struct QCryptoTLSCredsPSKClass QCryptoTLSCredsPSKClass;
+
+#define QCRYPTO_TLS_CREDS_PSKFILE "keys.psk"
+
+/**
+ * QCryptoTLSCredsPSK:
+ *
+ * The QCryptoTLSCredsPSK object provides a representation
+ * of the Pre-Shared Key credential used to perform a TLS handshake.
+ *
+ * This is a user creatable object, which can be instantiated
+ * via object_new_propv():
+ *
+ * <example>
+ *   <title>Creating TLS-PSK credential objects in code</title>
+ *   <programlisting>
+ *   Object *obj;
+ *   Error *err = NULL;
+ *   obj = object_new_propv(TYPE_QCRYPTO_TLS_CREDS_PSK,
+ *                          "tlscreds0",
+ *                          &err,
+ *                          "dir", "/path/to/dir",
+ *                          "endpoint", "client",
+ *                          NULL);
+ *   </programlisting>
+ * </example>
+ *
+ * Or via QMP:
+ *
+ * <example>
+ *   <title>Creating TLS-PSK credential objects via QMP</title>
+ *   <programlisting>
+ *    {
+ *       "execute": "object-add", "arguments": {
+ *          "id": "tlscreds0",
+ *          "qom-type": "tls-creds-psk",
+ *          "props": {
+ *             "dir": "/path/to/dir",
+ *             "endpoint": "client"
+ *          }
+ *       }
+ *    }
+ *   </programlisting>
+ * </example>
+ *
+ * Or via the CLI:
+ *
+ * <example>
+ *   <title>Creating TLS-PSK credential objects via CLI</title>
+ *   <programlisting>
+ *  qemu-system-x86_64 --object tls-creds-psk,id=tlscreds0,\
+ *          endpoint=client,dir=/path/to/dir[,username=qemu]
+ *   </programlisting>
+ * </example>
+ *
+ * The PSK file can be created and managed using psktool.
+ */
+
+struct QCryptoTLSCredsPSK {
+    QCryptoTLSCreds parent_obj;
+    char *username;
+#ifdef CONFIG_GNUTLS
+    union {
+        gnutls_psk_server_credentials_t server;
+        gnutls_psk_client_credentials_t client;
+    } data;
+#endif
+};
+
+
+struct QCryptoTLSCredsPSKClass {
+    QCryptoTLSCredsClass parent_class;
+};
+
+
+#endif /* QCRYPTO_TLSCREDSPSK_H */