Check system integrity when installing UEFI updates

Recently we had an update that changed the system-defined Platform Key, and
we've certainly had updates in the past that changed the Boot#### variables.

Store some core ACPI and UEFI system integrity state from before and after the
update which can be used to mark (waivable) test failures on the LVFS.

libfwupd/fwupd-enums.c

@@ -448,6 +448,8 @@ fwupd_plugin_flag_to_string(FwupdPluginFlags plugin_flag)
 		return "secure-config";
 	if (plugin_flag == FWUPD_PLUGIN_FLAG_MODULAR)
 		return "modular";
+	if (plugin_flag == FWUPD_PLUGIN_FLAG_MEASURE_SYSTEM_INTEGRITY)
+		return "measure-system-integrity";
 	return NULL;
 }
 
@@ -496,6 +498,8 @@ fwupd_plugin_flag_from_string(const gchar *plugin_flag)
 		return FWUPD_PLUGIN_FLAG_SECURE_CONFIG;
 	if (g_strcmp0(plugin_flag, "modular") == 0)
 		return FWUPD_PLUGIN_FLAG_MODULAR;
+	if (g_strcmp0(plugin_flag, "measure-system-integrity") == 0)
+		return FWUPD_PLUGIN_FLAG_MEASURE_SYSTEM_INTEGRITY;
 	return FWUPD_DEVICE_FLAG_UNKNOWN;
 }
 

libfwupd/fwupd-enums.h

@@ -879,6 +879,14 @@ typedef enum {
  * Since: 1.8.6
  */
 #define FWUPD_PLUGIN_FLAG_MODULAR (1u << 14)
+/**
+ * FWUPD_PLUGIN_FLAG_MEASURE_SYSTEM_INTEGRITY:
+ *
+ * The plugin will be checked that it preserves system state such as `KEK`, `PK`, `BOOT####` etc.
+ *
+ * Since: 1.8.7
+ */
+#define FWUPD_PLUGIN_FLAG_MEASURE_SYSTEM_INTEGRITY (1u << 15)
 /**
  * FWUPD_PLUGIN_FLAG_UNKNOWN:
  *

libfwupd/fwupd-self-test.c

@@ -170,7 +170,7 @@ fwupd_enums_func(void)
 		g_assert_cmpstr(tmp, !=, NULL);
 		g_assert_cmpint(fwupd_device_problem_from_string(tmp), ==, i);
 	}
-	for (guint64 i = 1; i <= FWUPD_PLUGIN_FLAG_MODULAR; i *= 2) {
+	for (guint64 i = 1; i <= FWUPD_PLUGIN_FLAG_MEASURE_SYSTEM_INTEGRITY; i *= 2) {
 		const gchar *tmp = fwupd_plugin_flag_to_string(i);
 		if (tmp == NULL)
 			g_warning("missing plugin flag 0x%x", (guint)i);

plugins/flashrom/fu-flashrom-plugin.c

@@ -339,6 +339,7 @@ fu_flashrom_plugin_constructed(GObject *obj)
 	fu_plugin_add_rule(plugin, FU_PLUGIN_RULE_METADATA_SOURCE, "linux_lockdown");
 	fu_plugin_add_rule(plugin, FU_PLUGIN_RULE_CONFLICTS, "coreboot"); /* obsoleted */
 	fu_plugin_add_flag(plugin, FWUPD_PLUGIN_FLAG_REQUIRE_HWID);
+	fu_plugin_add_flag(plugin, FWUPD_PLUGIN_FLAG_MEASURE_SYSTEM_INTEGRITY);
 }
 
 static void

plugins/uefi-capsule/fu-uefi-capsule-plugin.c

@@ -997,6 +997,7 @@ static void
 fu_uefi_capsule_plugin_init(FuUefiCapsulePlugin *self)
 {
 	self->bgrt = fu_uefi_bgrt_new();
+	fu_plugin_add_flag(FU_PLUGIN(self), FWUPD_PLUGIN_FLAG_MEASURE_SYSTEM_INTEGRITY);
 }
 
 static void

src/fu-engine-helper.c

@@ -1,5 +1,6 @@
 /*
  * Copyright (C) 2020 Mario Limonciello <mario.limonciello@dell.com>
+ * Copyright (C) 2022 Richard Hughes <richard@hughsie.com>
  *
  * SPDX-License-Identifier: LGPL-2.1+
  */
@@ -187,3 +188,106 @@ fu_engine_update_devices_file(FuEngine *self, GError **error)
 	target = g_build_filename(directory, "devices.json", NULL);
 	return g_file_set_contents(target, data, (gssize)len, error);
 }
+
+static void
+fu_engine_integrity_add_measurement(GHashTable *self, const gchar *id, GBytes *blob)
+{
+	g_autofree gchar *csum = g_compute_checksum_for_bytes(G_CHECKSUM_SHA256, blob);
+	g_hash_table_insert(self, g_strdup(id), g_steal_pointer(&csum));
+}
+
+static void
+fu_engine_integrity_measure_acpi(GHashTable *self)
+{
+	g_autofree gchar *path = fu_path_from_kind(FU_PATH_KIND_ACPI_TABLES);
+	const gchar *tables[] = {"SLIC", "MSDM", "TPM2", NULL};
+
+	for (guint i = 0; tables[i] != NULL; i++) {
+		g_autofree gchar *fn = g_build_filename(path, tables[i], NULL);
+		g_autoptr(GBytes) blob = NULL;
+
+		blob = fu_bytes_get_contents(fn, NULL);
+		if (blob != NULL && g_bytes_get_size(blob) > 0) {
+			g_autofree gchar *id = g_strdup_printf("ACPI:%s", tables[i]);
+			fu_engine_integrity_add_measurement(self, id, blob);
+		}
+	}
+}
+
+static void
+fu_engine_integrity_measure_uefi(GHashTable *self)
+{
+	struct {
+		const gchar *guid;
+		const gchar *name;
+	} keys[] = {{FU_EFIVAR_GUID_EFI_GLOBAL, "BootOrder"},
+		    {FU_EFIVAR_GUID_EFI_GLOBAL, "BootCurrent"},
+		    {FU_EFIVAR_GUID_EFI_GLOBAL, "KEK"},
+		    {FU_EFIVAR_GUID_EFI_GLOBAL, "PK"},
+		    {FU_EFIVAR_GUID_SECURITY_DATABASE, "db"},
+		    {FU_EFIVAR_GUID_SECURITY_DATABASE, "dbx"},
+		    {NULL, NULL}};
+
+	/* important keys */
+	for (guint i = 0; keys[i].guid != NULL; i++) {
+		g_autoptr(GBytes) blob =
+		    fu_efivar_get_data_bytes(keys[i].guid, keys[i].name, NULL, NULL);
+		if (blob != NULL) {
+			g_autofree gchar *id = g_strdup_printf("UEFI:%s", keys[i].name);
+			fu_engine_integrity_add_measurement(self, id, blob);
+		}
+	}
+
+	/* Boot#### */
+	for (guint i = 0; i < 0xFF; i++) {
+		g_autofree gchar *name = g_strdup_printf("Boot%04X", i);
+		g_autoptr(GBytes) blob =
+		    fu_efivar_get_data_bytes(FU_EFIVAR_GUID_EFI_GLOBAL, name, NULL, NULL);
+		if (blob != NULL && g_bytes_get_size(blob) > 0) {
+			g_autofree gchar *id = g_strdup_printf("UEFI:%s", name);
+			fu_engine_integrity_add_measurement(self, id, blob);
+		}
+	}
+}
+
+GHashTable *
+fu_engine_integrity_new(GError **error)
+{
+	g_autoptr(GHashTable) self = g_hash_table_new_full(g_str_hash, g_str_equal, g_free, g_free);
+
+	g_return_val_if_fail(error == NULL || *error == NULL, NULL);
+
+	fu_engine_integrity_measure_uefi(self);
+	fu_engine_integrity_measure_acpi(self);
+
+	/* nothing of use */
+	if (g_hash_table_size(self) == 0) {
+		g_set_error_literal(error, G_IO_ERROR, G_IO_ERROR_NOT_FOUND, "no measurements");
+		return NULL;
+	}
+
+	/* success */
+	return g_steal_pointer(&self);
+}
+
+gchar *
+fu_engine_integrity_to_string(GHashTable *self)
+{
+	GHashTableIter iter;
+	gpointer key, value;
+	g_autoptr(GPtrArray) array = g_ptr_array_new_with_free_func(g_free);
+
+	g_return_val_if_fail(self != NULL, NULL);
+
+	/* sanity check */
+	if (g_hash_table_size(self) == 0)
+		return NULL;
+
+	/* build into KV array */
+	g_hash_table_iter_init(&iter, self);
+	while (g_hash_table_iter_next(&iter, &key, &value)) {
+		g_ptr_array_add(array,
+				g_strdup_printf("%s=%s", (const gchar *)key, (const gchar *)value));
+	}
+	return fu_strjoin("\n", array);
+}

src/fu-engine-helper.h

@@ -1,5 +1,6 @@
 /*
  * Copyright (C) 2020 Mario Limonciello <mario.limonciello@dell.com>
+ * Copyright (C) 2022 Richard Hughes <richard@hughsie.com>
  *
  * SPDX-License-Identifier: LGPL-2.1+
  */
@@ -11,3 +12,8 @@ gboolean
 fu_engine_update_motd(FuEngine *self, GError **error);
 gboolean
 fu_engine_update_devices_file(FuEngine *self, GError **error);
+
+GHashTable *
+fu_engine_integrity_new(GError **error);
+gchar *
+fu_engine_integrity_to_string(GHashTable *self);

src/fu-engine.c

@@ -2413,6 +2413,16 @@ fu_engine_install_releases(FuEngine *self,
 	return TRUE;
 }
 
+static void
+fu_engine_update_release_integrity(FuEngine *self, FwupdRelease *release, const gchar *key)
+{
+	g_autoptr(GHashTable) integrity = fu_engine_integrity_new(NULL);
+	if (integrity != NULL) {
+		g_autofree gchar *str = fu_engine_integrity_to_string(integrity);
+		fwupd_release_add_metadata_item(FWUPD_RELEASE(release), key, str);
+	}
+}
+
 static gboolean
 fu_engine_add_release_metadata(FuEngine *self, FuRelease *release, FuPlugin *plugin, GError **error)
 {
@@ -2455,6 +2465,14 @@ fu_engine_add_release_metadata(FuEngine *self, FuRelease *release, FuPlugin *plu
 			}
 		}
 	}
+
+	/* measure the "old" system state */
+	if (fu_plugin_has_flag(plugin, FWUPD_PLUGIN_FLAG_MEASURE_SYSTEM_INTEGRITY)) {
+		fu_engine_update_release_integrity(self,
+						   FWUPD_RELEASE(release),
+						   "SystemIntegrityOld");
+	}
+
 	return TRUE;
 }
 
@@ -7315,6 +7333,13 @@ fu_engine_update_history_device(FuEngine *self, FuDevice *dev_history, GError **
 		}
 	}
 
+	/* measure the "new" system state */
+	plugin = fu_plugin_list_find_by_name(self->plugin_list, fu_device_get_plugin(dev), error);
+	if (plugin == NULL)
+		return FALSE;
+	if (fu_plugin_has_flag(plugin, FWUPD_PLUGIN_FLAG_MEASURE_SYSTEM_INTEGRITY))
+		fu_engine_update_release_integrity(self, rel_history, "SystemIntegrityNew");
+
 	/* the system is running with the new firmware version */
 	if (fu_version_compare(fu_device_get_version(dev),
 			       fwupd_release_get_version(rel_history),
@@ -7338,9 +7363,6 @@ fu_engine_update_history_device(FuEngine *self, FuDevice *dev_history, GError **
 	}
 
 	/* does the plugin know the update failure */
-	plugin = fu_plugin_list_find_by_name(self->plugin_list, fu_device_get_plugin(dev), error);
-	if (plugin == NULL)
-		return FALSE;
 	if (!fu_plugin_runner_get_results(plugin, dev, error))
 		return FALSE;
 

src/fu-util-common.c

@@ -1702,6 +1702,10 @@ fu_util_plugin_flag_to_string(FwupdPluginFlags plugin_flag)
 		/* TRANSLATORS: the plugin was created from a .so object, and was not built-in */
 		return _("Loaded from an external module");
 	}
+	if (plugin_flag == FWUPD_PLUGIN_FLAG_MEASURE_SYSTEM_INTEGRITY) {
+		/* TRANSLATORS: check various UEFI and ACPI tables are unchanged after the update */
+		return _("Will measure elements of system integrity around an update");
+	}
 	if (plugin_flag == FWUPD_PLUGIN_FLAG_EFIVAR_NOT_MOUNTED) {
 		/* TRANSLATORS: the user is using Gentoo/Arch and has screwed something up */
 		return _("Required efivarfs filesystem was not found");