module-portal: Use permission store for portal initiated clients

Detect what clients were started by the portal, and use the permission
store to determine permissions of existing and future nodes.

Clients are detected whether they are from the portal or not by
comparing the PID of the client with the PID of the owner of the
portal D-Bus name.

It is assumed that the portal will set an appropriate app_id, and a
comma seperated list of media roles (e.g. "Camera"), that should be
queried. If app_id is an empty string, it's assumed to be a
non-sandboxed client, and permissions are assumed to be allowing.

src/modules/module-portal.c

@@ -1,5 +1,6 @@
 /* PipeWire
  * Copyright (C) 2016 Wim Taymans <wim.taymans@gmail.com>
+ * Copyright (C) 2019 Red Hat Inc.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ -38,6 +39,12 @@
 #include "pipewire/module.h"
 #include "pipewire/utils.h"
 
+enum media_role {
+	MEDIA_ROLE_NONE = 0,
+	MEDIA_ROLE_CAMERA = 1 << 0,
+};
+#define MEDIA_ROLE_ALL (MEDIA_ROLE_CAMERA)
+
 struct impl {
 	struct pw_core *core;
 	struct pw_type *type;
@@ -50,6 +57,9 @@ struct impl {
 	struct spa_hook module_listener;
 
 	struct spa_list client_list;
+
+	DBusPendingCall *portal_pid_pending;
+	pid_t portal_pid;
 };
 
 struct client_info {
@@ -58,17 +68,12 @@ struct client_info {
 	struct pw_client *client;
 	struct spa_hook client_listener;
         struct spa_list resources;
-	struct spa_list async_pending;
-	bool checked;
-	bool camera_allowed;
-	bool sandboxed;
-};
 
-struct async_pending {
+	bool portal_managed;
-	struct spa_list link;
+	bool setup_complete;
-	struct client_info *cinfo;
+	char *app_id;
-	bool handled;
+	enum media_role media_roles;
-	char *handle;
+	enum media_role allowed_media_roles;
 };
 
 static struct client_info *find_client_info(struct impl *impl, struct pw_client *client)
@@ -82,143 +87,95 @@ static struct client_info *find_client_info(struct impl *impl, struct pw_client
 	return NULL;
 }
 
-static void close_request(struct async_pending *p)
-{
-	DBusMessage *m = NULL;
-	struct impl *impl = p->cinfo->impl;
-
-	pw_log_debug("pending %p: handle %s", p, p->handle);
-
-	if (!(m = dbus_message_new_method_call("org.freedesktop.portal.Request",
-					       p->handle,
-					       "org.freedesktop.portal.Request", "Close"))) {
-		pw_log_error("Failed to create message");
-		return;
-	}
-
-	if (!dbus_connection_send(impl->bus, m, NULL))
-		pw_log_error("Failed to send message");
-
-	dbus_message_unref(m);
-}
-
-static struct async_pending *find_pending(struct client_info *cinfo, const char *handle)
-{
-	struct async_pending *p;
-
-	spa_list_for_each(p, &cinfo->async_pending, link) {
-		if (strcmp(p->handle, handle) == 0)
-			return p;
-	}
-	return NULL;
-}
-
-static void free_pending(struct async_pending *p)
-{
-	if (!p->handled)
-		close_request(p);
-
-	pw_log_debug("pending %p: handle %s", p, p->handle);
-	spa_list_remove(&p->link);
-	free(p->handle);
-	free(p);
-}
-
 static void client_info_free(struct client_info *cinfo)
 {
-	struct async_pending *p, *tp;
-
-	spa_list_for_each_safe(p, tp, &cinfo->async_pending, link)
-		free_pending(p);
-
 	spa_hook_remove(&cinfo->client_listener);
 	spa_list_remove(&cinfo->link);
+	free(cinfo->app_id);
 	free(cinfo);
 }
 
-static int check_sandboxed(struct pw_client *client)
+static enum media_role media_role_from_string(const char *media_role_str)
 {
-	char root_path[2048];
+	if (strcmp(media_role_str, "Camera") == 0)
-	int root_fd, info_fd, res, pid;
+		return MEDIA_ROLE_CAMERA;
-	const char *str;
-	const struct pw_properties *props;
-	struct stat stat_buf;
-
-	if ((props = pw_client_get_properties(client)))
-		str = pw_properties_get(props, PW_CLIENT_PROP_UCRED_PID);
 	else
-		str = NULL;
+		return -1;
-
-	if (str) {
-		pid = atoi(str);
-		pw_log_info("client has trusted pid %d", pid);
-	} else {
-		pw_log_info("no trusted pid found, assuming not sandboxed\n");
-		return 0;
 }
 
-	sprintf(root_path, "/proc/%u/root", pid);
+static enum media_role parse_media_roles(const char *media_types_str)
-	root_fd = openat (AT_FDCWD, root_path, O_RDONLY | O_NONBLOCK | O_DIRECTORY | O_CLOEXEC | O_NOCTTY);
-	if (root_fd == -1) {
-		/* Not able to open the root dir shouldn't happen. Probably the app died and
-		 * we're failing due to /proc/$pid not existing. In that case fail instead
-		 * of treating this as privileged. */
-		res = -errno;
-		pw_log_error("failed to open \"%s\": %m", root_path);
-		return res;
-	}
-	info_fd = openat (root_fd, ".flatpak-info", O_RDONLY | O_CLOEXEC | O_NOCTTY);
-	close (root_fd);
-	if (info_fd == -1) {
-		if (errno == ENOENT) {
-			pw_log_debug("no .flatpak-info, client on the host");
-			/* No file => on the host */
-			return 0;
-		}
-		res = -errno;
-		pw_log_error("error opening .flatpak-info: %m");
-		return res;
-        }
-	if (fstat (info_fd, &stat_buf) != 0 || !S_ISREG (stat_buf.st_mode)) {
-		/* Some weird fd => failure, assume sandboxed */
-		close(info_fd);
-		pw_log_error("error fstat .flatpak-info: %m");
-	}
-	return 1;
-}
-
-static int get_client_prop(struct pw_client *client, const char *prop)
 {
+	enum media_role media_roles = 0;
+	char *buf_orig;
+	char *buf;
+
+	buf_orig = strdup(media_types_str);
+	buf = buf_orig;
+	while (buf) {
+		char *media_role_str;
+		enum media_role media_role;
+
+		media_role_str = buf;
+		strsep(&buf, ",");
+
+		media_role = media_role_from_string(media_role_str);
+		if (media_role != -1) {
+			media_roles |= MEDIA_ROLE_CAMERA;
+		}
+		else {
+			pw_log_debug("Client specified unknown media role '%s'",
+				     media_role_str);
+		}
+	}
+	free(buf);
+
+	return media_roles;
+}
+
+static enum media_role media_role_from_properties(const struct pw_properties *props)
+{
+	const char *media_class_str;
+	const char *media_role_str;
+
+	media_class_str = pw_properties_get(props, "media.class");
+	media_role_str = pw_properties_get(props, "media.role");
+
+	if (media_class_str == NULL)
+		return -1;
+
+	if (media_role_str == NULL)
+		return -1;
+
+	if (strcmp(media_class_str, "Video/Source") != 0)
+		return -1;
+
+	return media_role_from_string(media_role_str);
+}
+
+static void check_portal_managed(struct client_info *cinfo)
+{
+	struct impl *impl = cinfo->impl;
 	const struct pw_properties *props;
-	const char *str;
+
-	if ((props = pw_client_get_properties(client)) == NULL)
+	if (impl->portal_pid == 0)
-		return -EINVAL;
+		return;
-	if ((str = pw_properties_get(props, prop)) == NULL)
+
-		return -EINVAL;
+	props = pw_client_get_properties(cinfo->client);
-	return atoi(str);
+	if (props) {
+		const char *pid_str;
+		pid_t pid;
+
+		pid_str = pw_properties_get(props, PW_CLIENT_PROP_UCRED_PID);
+
+		pid = atoi(pid_str);
+
+		if (pid == impl->portal_pid) {
+			cinfo->portal_managed = true;
+
+			pw_log_debug("module %p: portal managed client %p added",
+				     impl, cinfo->client);
+		}
 	}
-
-static bool
-check_global_owner(struct pw_client *client, struct pw_global *global)
-{
-	struct pw_client *owner;
-	int owner_uid, client_uid;
-
-	if (global == NULL)
-		return false;
-
-	owner = pw_global_get_owner(global);
-	if (owner == NULL)
-		return false;
-
-	owner_uid = get_client_prop(owner, PW_CLIENT_PROP_UCRED_UID);
-	client_uid = get_client_prop(client, PW_CLIENT_PROP_UCRED_UID);
-
-	if (owner_uid < 0 || client_uid < 0)
-		return false;
-
-	/* same user can see eachothers objects */
-	return owner_uid == client_uid;
 }
 
 static int
@@ -228,177 +185,194 @@ set_global_permissions(void *data, struct pw_global *global)
 	struct impl *impl = cinfo->impl;
 	struct pw_client *client = cinfo->client;
 	const struct pw_properties *props;
-	const char *str;
 	struct spa_dict_item items[1];
 	int n_items = 0;
 	char perms[16];
+	bool set_permission;
 	bool allowed = false;
 
 	props = pw_global_get_properties(global);
 
 	if (pw_global_get_type(global) == impl->type->core) {
+		set_permission = true;
 		allowed = true;
 	}
-	else if (pw_global_get_type(global) == impl->type->factory) {
+	else if (props) {
-		if (props && (str = pw_properties_get(props, "factory.name"))) {
+		if (pw_global_get_type(global) == impl->type->factory) {
-			if (strcmp(str, "client-node") == 0)
+			const char *factory_name;
+
+			factory_name = pw_properties_get(props, "factory.name");
+			if (factory_name &&
+			    strcmp(factory_name, "client-node") == 0) {
+				set_permission = true;
 				allowed = true;
 			}
+			else {
+				set_permission = false;
+			}
+		}
+		else if (pw_global_get_type(global) == impl->type->module) {
+			set_permission = true;
+			allowed = true;
 		}
 		else if (pw_global_get_type(global) == impl->type->node) {
-		if (props && (str = pw_properties_get(props, "media.class"))) {
+			enum media_role media_role;
-			if (strcmp(str, "Video/Source") == 0 && cinfo->camera_allowed)
+
+			media_role = media_role_from_properties(props);
+
+			if (media_role == -1) {
+				set_permission = false;
+			}
+			else if (cinfo->allowed_media_roles & media_role) {
+				set_permission = true;
 				allowed = true;
 			}
-		allowed |= check_global_owner(client, global);
+			else if (cinfo->media_roles & media_role) {
+				set_permission = true;
+				allowed = false;
+			}
+			else {
+				set_permission = false;
+			}
+		}
+		else {
+			set_permission = false;
+		}
+	}
+	else {
+		set_permission = false;
 	}
-	else
-		allowed = check_global_owner(client, global);
 
-	snprintf(perms, sizeof(perms), "%d:%c--", pw_global_get_id(global), allowed ? 'r' : '-');
+	if (set_permission) {
-	items[n_items++] = SPA_DICT_ITEM_INIT(PW_CORE_PROXY_PERMISSIONS_GLOBAL, perms);
+		snprintf(perms, sizeof(perms),
-	pw_client_update_permissions(client, &SPA_DICT_INIT(items, n_items));
+			 "%d:%c--", pw_global_get_id(global), allowed ? 'r' : '-');
+		items[n_items++] =
+			SPA_DICT_ITEM_INIT(PW_CORE_PROXY_PERMISSIONS_GLOBAL,
+					   perms);
+		pw_client_update_permissions(client,
+					     &SPA_DICT_INIT(items, n_items));
+	}
 
 	return 0;
 }
 
-static DBusHandlerResult
+static bool
-portal_response(DBusConnection *connection, DBusMessage *msg, void *user_data)
+check_permission_allowed(DBusMessageIter *iter)
 {
-	struct client_info *cinfo = user_data;
+	bool allowed = false;
-	struct pw_client *client = cinfo->client;
 
-	if (dbus_message_is_signal(msg, "org.freedesktop.portal.Request", "Response")) {
+	while (dbus_message_iter_get_arg_type (iter) != DBUS_TYPE_INVALID) {
-		uint32_t response = 2;
+		const char *permission_value;
-		DBusError error;
-		struct async_pending *p;
 
-		dbus_error_init(&error);
+		dbus_message_iter_get_basic(iter, &permission_value);
 
-		dbus_connection_remove_filter(connection, portal_response, cinfo);
+		if (strcmp(permission_value, "yes") == 0) {
-
+			allowed = true;
-		if (!dbus_message_get_args
+			break;
-		    (msg, &error, DBUS_TYPE_UINT32, &response, DBUS_TYPE_INVALID)) {
+		}
-			pw_log_error("failed to parse Response: %s", error.message);
+		dbus_message_iter_next(iter);
-			dbus_error_free(&error);
 	}
 
-		p = find_pending(cinfo, dbus_message_get_path(msg));
+	return allowed;
-		if (p == NULL)
-			return DBUS_HANDLER_RESULT_HANDLED;
-
-		p->handled = true;
-
-		pw_log_debug("portal check result: %d", response);
-
-		if (response == 0) {
-			/* allowed */
-			cinfo->camera_allowed = true;
-			pw_log_debug("camera access allowed");
-		} else {
-			cinfo->camera_allowed = false;
-			pw_log_debug("camera access not allowed");
-		}
-		cinfo->checked = true;
-		pw_core_for_each_global(cinfo->impl->core, set_global_permissions, cinfo);
-
-		free_pending(p);
-		pw_client_set_busy(client, false);
-
-		return DBUS_HANDLER_RESULT_HANDLED;
-	}
-	return DBUS_HANDLER_RESULT_NOT_YET_HANDLED;
 }
 
-
+static void do_permission_store_check(struct client_info *cinfo)
-static void do_portal_check(struct client_info *cinfo)
 {
 	struct impl *impl = cinfo->impl;
 	struct pw_client *client = cinfo->client;
 	DBusMessage *m = NULL, *r = NULL;
 	DBusError error;
-	pid_t pid;
 	DBusMessageIter msg_iter;
-	DBusMessageIter dict_iter;
+	const char *table;
-	const char *handle;
+	const char *id;
-	const char *device;
+	DBusMessageIter r_iter;
-	struct async_pending *p;
+	DBusMessageIter permissions_iter;
 
-	pw_log_info("ask portal for client %p", client);
+	if (cinfo->app_id == NULL) {
-	pw_client_set_busy(client, true);
+		pw_log_debug("Ignoring portal check for broken portal managed client %p",
+			     client);
+		goto err_not_allowed;
+	}
+
+	if (cinfo->media_roles == 0) {
+		pw_log_debug("Ignoring portal check for portal client %p with static permissions",
+			     client);
+		pw_core_for_each_global(cinfo->impl->core,
+					set_global_permissions,
+					cinfo);
+		return;
+	}
+
+	if (strcmp(cinfo->app_id, "") == 0) {
+		pw_log_debug("Ignoring portal check for non-sandboxed portal client %p",
+			     client);
+		cinfo->allowed_media_roles = MEDIA_ROLE_ALL;
+		pw_core_for_each_global(cinfo->impl->core,
+					set_global_permissions,
+					cinfo);
+		return;
+	}
+
+	cinfo->allowed_media_roles = MEDIA_ROLE_NONE;
 
 	dbus_error_init(&error);
 
-	if (!(m = dbus_message_new_method_call("org.freedesktop.portal.Desktop",
+	m = dbus_message_new_method_call("org.freedesktop.impl.portal.PermissionStore",
-					       "/org/freedesktop/portal/desktop",
+					 "/org/freedesktop/impl/portal/PermissionStore",
-					       "org.freedesktop.portal.Device", "AccessDevice")))
+					 "org.freedesktop.impl.portal.PermissionStore",
-		goto no_method_call;
+					 "Lookup");
-
-	device = "camera";
-
-	pid = get_client_prop(client, PW_CLIENT_PROP_UCRED_PID);
-	if (pid < 0)
-		goto not_allowed;
-	if (!dbus_message_append_args(m, DBUS_TYPE_UINT32, &pid, DBUS_TYPE_INVALID))
-		goto message_failed;
 
 	dbus_message_iter_init_append(m, &msg_iter);
-	dbus_message_iter_open_container(&msg_iter, DBUS_TYPE_ARRAY, "s", &dict_iter);
+	table = "devices";
-	dbus_message_iter_append_basic(&dict_iter, DBUS_TYPE_STRING, &device);
+	dbus_message_iter_append_basic(&msg_iter, DBUS_TYPE_STRING, &table);
-	dbus_message_iter_close_container(&msg_iter, &dict_iter);
+	id = "camera";
+	dbus_message_iter_append_basic(&msg_iter, DBUS_TYPE_STRING, &id);
 
-	dbus_message_iter_open_container(&msg_iter, DBUS_TYPE_ARRAY, "{sv}", &dict_iter);
+	if (!(r = dbus_connection_send_with_reply_and_block(impl->bus, m, -1, &error))) {
-	dbus_message_iter_close_container(&msg_iter, &dict_iter);
+		pw_log_error("Failed to call permission store: %s", error.message);
-
+		dbus_error_free(&error);
-	if (!(r = dbus_connection_send_with_reply_and_block(impl->bus, m, -1, &error)))
+		goto err_not_allowed;
-		goto send_failed;
+	}
 
 	dbus_message_unref(m);
 
-	if (!dbus_message_get_args(r, &error, DBUS_TYPE_OBJECT_PATH, &handle, DBUS_TYPE_INVALID))
+	dbus_message_iter_init(r, &r_iter);
-		goto parse_failed;
+	dbus_message_iter_recurse(&r_iter, &permissions_iter);
+	while (dbus_message_iter_get_arg_type(&permissions_iter) !=
+	       DBUS_TYPE_INVALID) {
+		DBusMessageIter permissions_entry_iter;
+		const char *app_id;
+		DBusMessageIter permission_values_iter;
+		bool camera_allowed;
+
+		dbus_message_iter_recurse(&permissions_iter,
+					  &permissions_entry_iter);
+		dbus_message_iter_get_basic(&permissions_entry_iter, &app_id);
+
+		if (strcmp(app_id, cinfo->app_id) != 0) {
+			dbus_message_iter_next(&permissions_iter);
+			continue;
+		}
+
+		dbus_message_iter_next(&permissions_entry_iter);
+		dbus_message_iter_recurse(&permissions_entry_iter,
+					  &permission_values_iter);
+
+		camera_allowed = check_permission_allowed(&permission_values_iter);
+		cinfo->allowed_media_roles |=
+			camera_allowed ? MEDIA_ROLE_CAMERA : MEDIA_ROLE_NONE;
+		pw_core_for_each_global(cinfo->impl->core,
+					set_global_permissions,
+					cinfo);
+
+		break;
+	}
 
 	dbus_message_unref(r);
 
-	dbus_bus_add_match(impl->bus,
-			   "type='signal',interface='org.freedesktop.portal.Request'", &error);
-	dbus_connection_flush(impl->bus);
-	if (dbus_error_is_set(&error))
-		goto subscribe_failed;
-
-	dbus_connection_add_filter(impl->bus, portal_response, cinfo, NULL);
-
-	p = calloc(1, sizeof(struct async_pending));
-	p->cinfo = cinfo;
-	p->handle = strdup(handle);
-	p->handled = false;
-
-	pw_log_debug("pending %p: handle %s", p, handle);
-	spa_list_append(&cinfo->async_pending, &p->link);
-
 	return;
 
-      no_method_call:
+      err_not_allowed:
-	pw_log_error("Failed to create message");
-	goto not_allowed;
-      message_failed:
-	dbus_message_unref(m);
-	goto not_allowed;
-      send_failed:
-	pw_log_error("Failed to call portal: %s", error.message);
-	dbus_error_free(&error);
-	dbus_message_unref(m);
-	goto not_allowed;
-      parse_failed:
-	pw_log_error("Failed to parse AccessDevice result: %s", error.message);
-	dbus_error_free(&error);
-	dbus_message_unref(r);
-	goto not_allowed;
-      subscribe_failed:
-	pw_log_error("Failed to subscribe to Request signal: %s", error.message);
-	dbus_error_free(&error);
-	goto not_allowed;
-      not_allowed:
 	pw_resource_error(pw_client_get_core_resource(client), -EPERM, "not allowed");
 	return;
 }
@@ -406,22 +380,45 @@ static void do_portal_check(struct client_info *cinfo)
 static void client_info_changed(void *data, struct pw_client_info *info)
 {
 	struct client_info *cinfo = data;
-	const char *str;
+	const struct pw_properties *properties;
+	const char *app_id;
+	const char *media_roles;
+
+	if (!cinfo->portal_managed)
+		return;
 
 	if (info->props == NULL)
 		return;
 
-	if ((str = spa_dict_lookup(info->props, "pipewire.access")) == NULL)
+	if (cinfo->setup_complete)
 		return;
+	cinfo->setup_complete = true;
 
-	if (strcmp(str, "flatpak") != 0)
+	properties = pw_client_get_properties(cinfo->client);
+	if (properties == NULL) {
+		pw_log_error("Portal managed client didn't have any properties");
 		return;
-
+	}
-	if (cinfo->checked)
+	app_id = pw_properties_get(properties,
+				   "pipewire.access.portal.app_id");
+	if (app_id == NULL) {
+		pw_log_error("Portal managed client didn't set app_id");
 		return;
+	}
+	media_roles = pw_properties_get(properties,
+					"pipewire.access.portal.media_roles");
 
-	pw_log_debug("module %p: client %p set to flatpak access", cinfo->impl, cinfo->client);
+	if (media_roles == NULL) {
-	do_portal_check(cinfo);
+		pw_log_error("Portal managed client didn't set media_roles");
+		return;
+	}
+
+	cinfo->app_id = strdup(app_id);
+	cinfo->media_roles = parse_media_roles(media_roles);
+
+	pw_log_debug("module %p: client %p with app_id '%s' set to portal access",
+		     cinfo->impl, cinfo->client, cinfo->app_id);
+	do_permission_store_check(cinfo);
 }
 
 static const struct pw_client_events client_events = {
@@ -434,40 +431,22 @@ core_global_added(void *data, struct pw_global *global)
 {
 	struct impl *impl = data;
 	struct client_info *cinfo;
-	int res;
 
 	if (pw_global_get_type(global) == impl->type->client) {
 		struct pw_client *client = pw_global_get_object(global);
 
-		/* clients are placed in a list and we do a portal check when needed */
 		cinfo = calloc(1, sizeof(struct client_info));
 		cinfo->impl = impl;
 		cinfo->client = client;
-		spa_list_init(&cinfo->async_pending);
 		pw_client_add_listener(client, &cinfo->client_listener, &client_events, cinfo);
 
 		spa_list_append(&impl->client_list, &cinfo->link);
 
-		res = check_sandboxed(client);
+		check_portal_managed(cinfo);
-		if (res == 0) {
-			pw_log_debug("module %p: non sandboxed client %p", impl, client);
-			return;
-		}
-		cinfo->sandboxed = true;
-
-		if (res < 0) {
-			pw_log_warn("module %p: client %p sandbox check failed: %s",
-					impl, client, spa_strerror(res));
-		}
-		else {
-			pw_log_debug("module %p: sandboxed client %p added", impl, client);
-		}
-
-		do_portal_check(cinfo);
 	}
 	else {
 		spa_list_for_each(cinfo, &impl->client_list, link) {
-			if (cinfo->sandboxed)
+			if (cinfo->portal_managed)
 				set_global_permissions(cinfo, global);
 		}
 	}
@@ -519,6 +498,234 @@ static const struct pw_module_events module_events = {
 	.destroy = module_destroy,
 };
 
+static void on_portal_pid_received(DBusPendingCall *pending,
+				   void *user_data)
+{
+	struct impl *impl = user_data;
+	DBusMessage *m;
+	DBusError error;
+	uint32_t portal_pid = 0;
+
+	m = dbus_pending_call_steal_reply(pending);
+	dbus_pending_call_unref(pending);
+	impl->portal_pid_pending = NULL;
+
+	if (!m) {
+		pw_log_error("Failed to receive portal pid");
+		return;
+	}
+
+	dbus_error_init(&error);
+	dbus_message_get_args(m, &error, DBUS_TYPE_UINT32, &portal_pid,
+			      DBUS_TYPE_INVALID);
+	dbus_message_unref(m);
+
+	if (dbus_error_is_set(&error)) {
+		impl->portal_pid = 0;
+	}
+	else {
+		struct client_info *cinfo;
+
+		impl->portal_pid = portal_pid;
+
+		spa_list_for_each(cinfo, &impl->client_list, link) {
+			if (cinfo->portal_managed)
+				continue;
+
+			check_portal_managed(cinfo);
+		}
+	}
+}
+
+static void update_portal_pid(struct impl *impl)
+{
+	DBusMessage *m;
+	const char *name;
+	DBusPendingCall *pending;
+
+	impl->portal_pid = 0;
+
+	m = dbus_message_new_method_call("org.freedesktop.DBus",
+					 "/",
+					 "org.freedesktop.DBus",
+					 "GetConnectionUnixProcessID");
+
+	name = "org.freedesktop.portal.Desktop";
+	dbus_message_append_args(m,
+				 DBUS_TYPE_STRING, &name,
+				 DBUS_TYPE_INVALID);
+
+	dbus_connection_send_with_reply(impl->bus, m, &pending, -1);
+	dbus_pending_call_set_notify(pending, on_portal_pid_received, impl, NULL);
+	if (impl->portal_pid_pending != NULL) {
+		dbus_pending_call_cancel(impl->portal_pid_pending);
+		dbus_pending_call_unref(impl->portal_pid_pending);
+	}
+	impl->portal_pid_pending = pending;
+}
+
+static DBusHandlerResult name_owner_changed_handler(DBusConnection *connection,
+						    DBusMessage *message,
+						    void *user_data)
+{
+	struct impl *impl = user_data;
+	const char *name;
+	const char *old_owner;
+	const char *new_owner;
+
+	if (!dbus_message_is_signal(message, "org.freedesktop.DBus",
+				   "NameOwnerChanged"))
+		return DBUS_HANDLER_RESULT_NOT_YET_HANDLED;
+
+	if (!dbus_message_get_args(message, NULL,
+				   DBUS_TYPE_STRING, &name,
+				   DBUS_TYPE_STRING, &old_owner,
+				   DBUS_TYPE_STRING, &new_owner,
+				   DBUS_TYPE_INVALID)) {
+		pw_log_error("Failed to get OwnerChanged args");
+		return DBUS_HANDLER_RESULT_NOT_YET_HANDLED;
+	}
+
+	if (strcmp(name, "org.freedesktop.portal.Desktop") != 0)
+		return DBUS_HANDLER_RESULT_NOT_YET_HANDLED;
+
+	if (strcmp(new_owner, "") == 0) {
+		impl->portal_pid = 0;
+		if (impl->portal_pid_pending != NULL) {
+			dbus_pending_call_cancel(impl->portal_pid_pending);
+			dbus_pending_call_unref(impl->portal_pid_pending);
+		}
+	}
+	else {
+		update_portal_pid(impl);
+	}
+
+	return DBUS_HANDLER_RESULT_HANDLED;
+}
+
+static DBusHandlerResult permission_store_changed_handler(DBusConnection *connection,
+							  DBusMessage *message,
+							  void *user_data)
+{
+	struct impl *impl = user_data;
+	struct client_info *cinfo;
+	DBusMessageIter iter;
+	const char *table;
+	const char *id;
+	dbus_bool_t deleted;
+	DBusMessageIter permissions_iter;
+
+	if (!dbus_message_is_signal(message, "org.freedesktop.impl.portal.PermissionStore",
+				   "Changed"))
+		return DBUS_HANDLER_RESULT_NOT_YET_HANDLED;
+
+	spa_list_for_each(cinfo, &impl->client_list, link) {
+		if (!cinfo->portal_managed)
+			continue;
+
+		cinfo->allowed_media_roles = MEDIA_ROLE_NONE;
+	}
+
+	dbus_message_iter_init(message, &iter);
+	dbus_message_iter_get_basic(&iter, &table);
+
+	dbus_message_iter_next(&iter);
+	dbus_message_iter_get_basic(&iter, &id);
+
+	if (strcmp(table, "devices") != 0 || strcmp(id, "camera") != 0)
+		return DBUS_HANDLER_RESULT_HANDLED;
+
+	dbus_message_iter_next(&iter);
+	dbus_message_iter_get_basic(&iter, &deleted);
+
+	dbus_message_iter_next(&iter);
+	/* data variant (ignored) */
+
+	dbus_message_iter_next(&iter);
+	dbus_message_iter_recurse(&iter, &permissions_iter);
+	while (dbus_message_iter_get_arg_type(&permissions_iter) !=
+	       DBUS_TYPE_INVALID) {
+		DBusMessageIter permissions_entry_iter;
+		const char *app_id;
+		DBusMessageIter permission_values_iter;
+		bool camera_allowed;
+
+		dbus_message_iter_recurse(&permissions_iter,
+					  &permissions_entry_iter);
+		dbus_message_iter_get_basic(&permissions_entry_iter, &app_id);
+
+		dbus_message_iter_next(&permissions_entry_iter);
+		dbus_message_iter_recurse(&permissions_entry_iter,
+					  &permission_values_iter);
+
+		camera_allowed = check_permission_allowed(&permission_values_iter);
+
+		spa_list_for_each(cinfo, &impl->client_list, link) {
+			if (!cinfo->portal_managed)
+				continue;
+
+			if (strcmp(cinfo->app_id, app_id) != 0)
+				continue;
+
+			if (!(cinfo->media_roles & MEDIA_ROLE_CAMERA))
+				continue;
+
+			if (camera_allowed)
+				cinfo->allowed_media_roles |= MEDIA_ROLE_CAMERA;
+			pw_core_for_each_global(cinfo->impl->core,
+						set_global_permissions,
+						cinfo);
+		}
+
+		dbus_message_iter_next(&permissions_iter);
+	}
+
+	return DBUS_HANDLER_RESULT_HANDLED;
+}
+
+static int init_dbus_connection(struct impl *impl)
+{
+	DBusError error;
+
+	impl->bus = spa_dbus_connection_get(impl->conn);
+
+	dbus_error_init(&error);
+
+	dbus_bus_add_match(impl->bus,
+			   "type='signal',\
+			   sender='org.freedesktop.DBus',\
+			   interface='org.freedesktop.DBus',\
+			   member='NameOwnerChanged'",
+			   &error);
+	if (dbus_error_is_set(&error)) {
+		pw_log_error("Failed to add name owner changed listener: %s",
+			     error.message);
+		dbus_error_free(&error);
+		return -1;
+	}
+
+	dbus_bus_add_match(impl->bus,
+			   "type='signal',\
+			   sender='org.freedesktop.impl.portal.PermissionStore',\
+			   interface='org.freedesktop.impl.portal.PermissionStore',\
+			   member='Changed'",
+			   &error);
+	if (dbus_error_is_set(&error)) {
+		pw_log_error("Failed to add permission store changed listener: %s",
+			     error.message);
+		dbus_error_free(&error);
+		return -1;
+	}
+
+	dbus_connection_add_filter(impl->bus, name_owner_changed_handler,
+				   impl, NULL);
+	dbus_connection_add_filter(impl->bus, permission_store_changed_handler,
+				   impl, NULL);
+	update_portal_pid(impl);
+
+	return 0;
+}
+
 static int module_init(struct pw_module *module, struct pw_properties *properties)
 {
 	struct pw_core *core = pw_module_get_core(module);
@@ -547,7 +754,8 @@ static int module_init(struct pw_module *module, struct pw_properties *propertie
 	if (impl->conn == NULL)
 		goto error;
 
-	impl->bus = spa_dbus_connection_get(impl->conn);
+	if (init_dbus_connection(impl) != 0)
+		goto error;
 
 	spa_list_init(&impl->client_list);