lib/sign: initial implementation

Added the initial version of signing interface allowing to allowing to
sign and verify commits.
Implemented initial signing modules:
 - dummy -- simple module allowing to sign/verify with ASCII string
 - ed25519 -- module allowing to sign/verify commit with ed25519
   (EdDSA) signature scheme provided by libsodium library.

Signed-off-by: Denis Pynkin <denis.pynkin@collabora.com>

src/libostree/ostree-sign-dummy.c

@@ -0,0 +1,181 @@
+/* vim:set et sw=2 cin cino=t0,f0,(0,{s,>2s,n-s,^-s,e2s: */
+
+/*
+ * Copyright © 2019 Collabora Ltd.
+ *
+ * SPDX-License-Identifier: LGPL-2.0+
+ *
+ * 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, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ *
+ */
+
+#include "config.h"
+
+#include "ostree-sign-dummy.h"
+#include <string.h>
+
+#define OSTREE_SIGN_DUMMY_NAME "dummy"
+
+#define OSTREE_SIGN_METADATA_DUMMY_KEY "ostree.sign.dummy"
+#define OSTREE_SIGN_METADATA_DUMMY_TYPE "aay"
+
+#define OSTREE_SIGN_DUMMY_SIGNATURE "dummysign"
+
+struct _OstreeSignDummy
+{
+  GObject parent;
+  gchar *signature_ascii;
+};
+
+static void
+ostree_sign_dummy_iface_init (OstreeSignInterface *self);
+
+G_DEFINE_TYPE_WITH_CODE (OstreeSignDummy, ostree_sign_dummy, G_TYPE_OBJECT,
+        G_IMPLEMENT_INTERFACE (OSTREE_TYPE_SIGN, ostree_sign_dummy_iface_init));
+
+static void
+ostree_sign_dummy_iface_init (OstreeSignInterface *self)
+{
+  g_debug ("%s enter", __FUNCTION__);
+
+  self->data = ostree_sign_dummy_data;
+  self->get_name = ostree_sign_dummy_get_name;
+  self->metadata_key = ostree_sign_dummy_metadata_key;
+  self->metadata_format = ostree_sign_dummy_metadata_format;
+  self->metadata_verify = ostree_sign_dummy_metadata_verify;
+  self->set_sk = ostree_sign_dummy_set_signature;
+  self->set_pk = ostree_sign_dummy_set_signature;
+}
+
+static void
+ostree_sign_dummy_class_init (OstreeSignDummyClass *self)
+{
+  g_debug ("%s enter", __FUNCTION__);
+  GObjectClass *object_class = G_OBJECT_CLASS(self);
+}
+
+static void
+ostree_sign_dummy_init (OstreeSignDummy *self)
+{
+  g_debug ("%s enter", __FUNCTION__);
+
+  self->signature_ascii = g_strdup(OSTREE_SIGN_DUMMY_SIGNATURE);
+}
+
+gboolean ostree_sign_dummy_set_signature (OstreeSign *self, GVariant *key, GError **error)
+{
+  g_debug ("%s enter", __FUNCTION__);
+
+  OstreeSignDummy *sign =  ostree_sign_dummy_get_instance_private(OSTREE_SIGN_DUMMY(self));
+
+  if (sign->signature_ascii != NULL)
+    g_free(sign->signature_ascii);
+
+  sign->signature_ascii = g_variant_dup_string (key, 0);
+
+  return TRUE;
+}
+
+gboolean ostree_sign_dummy_data (OstreeSign *self,
+                                 GBytes *data,
+                                 GBytes **signature,
+                                 GCancellable *cancellable,
+                                 GError **error)
+{
+
+  g_debug ("%s enter", __FUNCTION__);
+  g_return_val_if_fail (OSTREE_IS_SIGN (self), FALSE);
+
+  OstreeSignDummy *sign =  ostree_sign_dummy_get_instance_private(OSTREE_SIGN_DUMMY(self));
+
+  *signature = g_bytes_new (sign->signature_ascii, strlen(sign->signature_ascii));
+
+  return TRUE;
+}
+
+gchar * ostree_sign_dummy_get_name (OstreeSign *self)
+{
+  g_debug ("%s enter", __FUNCTION__);
+  g_return_val_if_fail (OSTREE_IS_SIGN (self), FALSE);
+
+  g_autofree gchar *name = g_strdup(OSTREE_SIGN_DUMMY_NAME);
+
+  return g_steal_pointer (&name);
+}
+
+gchar * ostree_sign_dummy_metadata_key (OstreeSign *self)
+{
+  g_debug ("%s enter", __FUNCTION__);
+
+  g_autofree gchar *key = g_strdup(OSTREE_SIGN_METADATA_DUMMY_KEY);
+  return g_steal_pointer (&key);
+}
+
+gchar * ostree_sign_dummy_metadata_format (OstreeSign *self)
+{
+  g_debug ("%s enter", __FUNCTION__);
+
+  g_autofree gchar *type = g_strdup(OSTREE_SIGN_METADATA_DUMMY_TYPE);
+  return g_steal_pointer (&type);
+}
+
+gboolean ostree_sign_dummy_metadata_verify (OstreeSign *self,
+                                            GBytes     *data,
+                                            GVariant   *signatures,
+                                            GError     **error)
+{
+  g_debug ("%s enter", __FUNCTION__);
+  g_return_val_if_fail (OSTREE_IS_SIGN (self), FALSE);
+  g_return_val_if_fail (data != NULL, FALSE);
+
+  OstreeSignDummy *sign =  ostree_sign_dummy_get_instance_private(OSTREE_SIGN_DUMMY(self));
+
+  gboolean ret = FALSE;
+
+  if (signatures == NULL)
+    {
+      g_set_error_literal (error,
+                           G_IO_ERROR, G_IO_ERROR_FAILED,
+                           "signature: dummy: commit have no signatures of my type");
+      goto err;
+    }
+
+
+  if (!g_variant_is_of_type (signatures, (GVariantType *) OSTREE_SIGN_METADATA_DUMMY_TYPE))
+    {
+      g_set_error_literal (error,
+                           G_IO_ERROR, G_IO_ERROR_FAILED,
+                           "signature: dummy: wrong type passed for verification");
+      goto err;
+    }
+
+  for (gsize i = 0; i < g_variant_n_children(signatures); i++)
+    {
+      g_autoptr (GVariant) child = g_variant_get_child_value (signatures, i);
+      g_autoptr (GBytes) signature = g_variant_get_data_as_bytes(child);
+
+      gsize sign_size = 0;
+      g_bytes_get_data (signature, &sign_size);
+      g_autofree gchar *sign_ascii = g_strndup(g_bytes_get_data (signature, NULL), sign_size);
+      g_debug("Read signature %d: %s", (gint)i, sign_ascii);
+
+      if (!g_strcmp0(sign_ascii, sign->signature_ascii))
+          ret = TRUE;
+    }
+
+err:
+  return ret;
+}