crypto: introduce new base module for TLS credentials

Introduce a QCryptoTLSCreds class to act as the base class for
storing TLS credentials. This will be later subclassed to provide
handling of anonymous and x509 credential types. The subclasses
will be user creatable objects, so instances can be created &
deleted via 'object-add' and 'object-del' QMP commands respectively,
or via the -object command line arg.

If the credentials cannot be initialized an error will be reported
as a QMP reply, or on stderr respectively.

The idea is to make it possible to represent and manage TLS
credentials independently of the network service that is using
them. This will enable multiple services to use the same set of
credentials and minimize code duplication. A later patch will
convert the current VNC server TLS code over to use this object.

The representation of credentials will be functionally equivalent
to that currently implemented in the VNC server with one exception.
The new code has the ability to (optionally) load a pre-generated
set of diffie-hellman parameters, if the file dh-params.pem exists,
whereas the current VNC server will always generate them on startup.
This is beneficial for admins who wish to avoid the (small) time
sink of generating DH parameters at startup and/or avoid depleting
entropy.

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

crypto/Makefile.objs

@@ -3,6 +3,7 @@ crypto-obj-y += hash.o
 crypto-obj-y += aes.o
 crypto-obj-y += desrfb.o
 crypto-obj-y += cipher.o
+crypto-obj-y += tlscreds.o
 
 # Let the userspace emulators avoid linking gnutls/etc
 crypto-aes-obj-y = aes.o

crypto/tlscreds.c

@@ -0,0 +1,251 @@
+/*
+ * QEMU crypto TLS credential support
+ *
+ * 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/>.
+ *
+ */
+
+#include "crypto/tlscredspriv.h"
+#include "trace.h"
+
+#define DH_BITS 2048
+
+#ifdef CONFIG_GNUTLS
+int
+qcrypto_tls_creds_get_dh_params_file(QCryptoTLSCreds *creds,
+                                     const char *filename,
+                                     gnutls_dh_params_t *dh_params,
+                                     Error **errp)
+{
+    int ret;
+
+    trace_qcrypto_tls_creds_load_dh(creds, filename ? filename : "<generated>");
+
+    if (filename == NULL) {
+        ret = gnutls_dh_params_init(dh_params);
+        if (ret < 0) {
+            error_setg(errp, "Unable to initialize DH parameters: %s",
+                       gnutls_strerror(ret));
+            return -1;
+        }
+        ret = gnutls_dh_params_generate2(*dh_params, DH_BITS);
+        if (ret < 0) {
+            gnutls_dh_params_deinit(*dh_params);
+            *dh_params = NULL;
+            error_setg(errp, "Unable to generate DH parameters: %s",
+                       gnutls_strerror(ret));
+            return -1;
+        }
+    } else {
+        GError *gerr = NULL;
+        gchar *contents;
+        gsize len;
+        gnutls_datum_t data;
+        if (!g_file_get_contents(filename,
+                                 &contents,
+                                 &len,
+                                 &gerr)) {
+
+            error_setg(errp, "%s", gerr->message);
+            g_error_free(gerr);
+            return -1;
+        }
+        data.data = (unsigned char *)contents;
+        data.size = len;
+        ret = gnutls_dh_params_init(dh_params);
+        if (ret < 0) {
+            g_free(contents);
+            error_setg(errp, "Unable to initialize DH parameters: %s",
+                       gnutls_strerror(ret));
+            return -1;
+        }
+        ret = gnutls_dh_params_import_pkcs3(*dh_params,
+                                            &data,
+                                            GNUTLS_X509_FMT_PEM);
+        g_free(contents);
+        if (ret < 0) {
+            gnutls_dh_params_deinit(*dh_params);
+            *dh_params = NULL;
+            error_setg(errp, "Unable to load DH parameters from %s: %s",
+                       filename, gnutls_strerror(ret));
+            return -1;
+        }
+    }
+
+    return 0;
+}
+
+
+int
+qcrypto_tls_creds_get_path(QCryptoTLSCreds *creds,
+                           const char *filename,
+                           bool required,
+                           char **cred,
+                           Error **errp)
+{
+    struct stat sb;
+    int ret = -1;
+
+    if (!creds->dir) {
+        if (required) {
+            error_setg(errp, "Missing 'dir' property value");
+            return -1;
+        } else {
+            return 0;
+        }
+    }
+
+    *cred = g_strdup_printf("%s/%s", creds->dir, filename);
+
+    if (stat(*cred, &sb) < 0) {
+        if (errno == ENOENT && !required) {
+            ret = 0;
+        } else {
+            error_setg_errno(errp, errno,
+                             "Unable to access credentials %s",
+                             *cred);
+        }
+        g_free(*cred);
+        *cred = NULL;
+        goto cleanup;
+    }
+
+    trace_qcrypto_tls_creds_get_path(creds, filename,
+                                     *cred ? *cred : "<none>");
+    ret = 0;
+ cleanup:
+    return ret;
+}
+
+
+#endif /* ! CONFIG_GNUTLS */
+
+
+static void
+qcrypto_tls_creds_prop_set_verify(Object *obj,
+                                  bool value,
+                                  Error **errp G_GNUC_UNUSED)
+{
+    QCryptoTLSCreds *creds = QCRYPTO_TLS_CREDS(obj);
+
+    creds->verifyPeer = value;
+}
+
+
+static bool
+qcrypto_tls_creds_prop_get_verify(Object *obj,
+                                  Error **errp G_GNUC_UNUSED)
+{
+    QCryptoTLSCreds *creds = QCRYPTO_TLS_CREDS(obj);
+
+    return creds->verifyPeer;
+}
+
+
+static void
+qcrypto_tls_creds_prop_set_dir(Object *obj,
+                               const char *value,
+                               Error **errp G_GNUC_UNUSED)
+{
+    QCryptoTLSCreds *creds = QCRYPTO_TLS_CREDS(obj);
+
+    creds->dir = g_strdup(value);
+}
+
+
+static char *
+qcrypto_tls_creds_prop_get_dir(Object *obj,
+                               Error **errp G_GNUC_UNUSED)
+{
+    QCryptoTLSCreds *creds = QCRYPTO_TLS_CREDS(obj);
+
+    return g_strdup(creds->dir);
+}
+
+
+static void
+qcrypto_tls_creds_prop_set_endpoint(Object *obj,
+                                    int value,
+                                    Error **errp G_GNUC_UNUSED)
+{
+    QCryptoTLSCreds *creds = QCRYPTO_TLS_CREDS(obj);
+
+    creds->endpoint = value;
+}
+
+
+static int
+qcrypto_tls_creds_prop_get_endpoint(Object *obj,
+                                    Error **errp G_GNUC_UNUSED)
+{
+    QCryptoTLSCreds *creds = QCRYPTO_TLS_CREDS(obj);
+
+    return creds->endpoint;
+}
+
+
+static void
+qcrypto_tls_creds_init(Object *obj)
+{
+    QCryptoTLSCreds *creds = QCRYPTO_TLS_CREDS(obj);
+
+    creds->verifyPeer = true;
+
+    object_property_add_bool(obj, "verify-peer",
+                             qcrypto_tls_creds_prop_get_verify,
+                             qcrypto_tls_creds_prop_set_verify,
+                             NULL);
+    object_property_add_str(obj, "dir",
+                            qcrypto_tls_creds_prop_get_dir,
+                            qcrypto_tls_creds_prop_set_dir,
+                            NULL);
+    object_property_add_enum(obj, "endpoint",
+                             "QCryptoTLSCredsEndpoint",
+                             QCryptoTLSCredsEndpoint_lookup,
+                             qcrypto_tls_creds_prop_get_endpoint,
+                             qcrypto_tls_creds_prop_set_endpoint,
+                             NULL);
+}
+
+
+static void
+qcrypto_tls_creds_finalize(Object *obj)
+{
+    QCryptoTLSCreds *creds = QCRYPTO_TLS_CREDS(obj);
+
+    g_free(creds->dir);
+}
+
+
+static const TypeInfo qcrypto_tls_creds_info = {
+    .parent = TYPE_OBJECT,
+    .name = TYPE_QCRYPTO_TLS_CREDS,
+    .instance_size = sizeof(QCryptoTLSCreds),
+    .instance_init = qcrypto_tls_creds_init,
+    .instance_finalize = qcrypto_tls_creds_finalize,
+    .class_size = sizeof(QCryptoTLSCredsClass),
+    .abstract = true,
+};
+
+
+static void
+qcrypto_tls_creds_register_types(void)
+{
+    type_register_static(&qcrypto_tls_creds_info);
+}
+
+
+type_init(qcrypto_tls_creds_register_types);

crypto/tlscredspriv.h

@@ -0,0 +1,42 @@
+/*
+ * QEMU crypto TLS credential support private helpers
+ *
+ * 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 QCRYPTO_TLSCRED_PRIV_H__
+#define QCRYPTO_TLSCRED_PRIV_H__
+
+#include "crypto/tlscreds.h"
+
+#ifdef CONFIG_GNUTLS
+
+int qcrypto_tls_creds_get_path(QCryptoTLSCreds *creds,
+                               const char *filename,
+                               bool required,
+                               char **cred,
+                               Error **errp);
+
+int qcrypto_tls_creds_get_dh_params_file(QCryptoTLSCreds *creds,
+                                         const char *filename,
+                                         gnutls_dh_params_t *dh_params,
+                                         Error **errp);
+
+#endif
+
+#endif /* QCRYPTO_TLSCRED_PRIV_H__ */
+

include/crypto/tlscreds.h

@@ -0,0 +1,68 @@
+/*
+ * QEMU crypto TLS credential support
+ *
+ * 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 QCRYPTO_TLSCRED_H__
+#define QCRYPTO_TLSCRED_H__
+
+#include "qemu-common.h"
+#include "qapi/error.h"
+#include "qom/object.h"
+
+#ifdef CONFIG_GNUTLS
+#include <gnutls/gnutls.h>
+#endif
+
+#define TYPE_QCRYPTO_TLS_CREDS "tls-creds"
+#define QCRYPTO_TLS_CREDS(obj)                  \
+    OBJECT_CHECK(QCryptoTLSCreds, (obj), TYPE_QCRYPTO_TLS_CREDS)
+
+typedef struct QCryptoTLSCreds QCryptoTLSCreds;
+typedef struct QCryptoTLSCredsClass QCryptoTLSCredsClass;
+
+#define QCRYPTO_TLS_CREDS_DH_PARAMS "dh-params.pem"
+
+
+/**
+ * QCryptoTLSCreds:
+ *
+ * The QCryptoTLSCreds object is an abstract base for different
+ * types of TLS handshake credentials. Most commonly the
+ * QCryptoTLSCredsX509 subclass will be used to provide x509
+ * certificate credentials.
+ */
+
+struct QCryptoTLSCreds {
+    Object parent_obj;
+    char *dir;
+    QCryptoTLSCredsEndpoint endpoint;
+#ifdef CONFIG_GNUTLS
+    gnutls_dh_params_t dh_params;
+#endif
+    bool verifyPeer;
+};
+
+
+struct QCryptoTLSCredsClass {
+    ObjectClass parent_class;
+};
+
+
+#endif /* QCRYPTO_TLSCRED_H__ */
+

qapi-schema.json

@@ -5,6 +5,9 @@
 # QAPI common definitions
 { 'include': 'qapi/common.json' }
 
+# QAPI crypto definitions
+{ 'include': 'qapi/crypto.json' }
+
 # QAPI block definitions
 { 'include': 'qapi/block.json' }