pipewire/src/modules/module-flatpak.c

/* PipeWire
 * Copyright (C) 2016 Wim Taymans <wim.taymans@gmail.com>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library 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
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with this library; if not, write to the
 * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 */

#include <string.h>
#include <stdio.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>

#include "config.h"

#include <dbus/dbus.h>

#include "pipewire/interfaces.h"
#include "pipewire/utils.h"

#include "pipewire/core.h"
#include "pipewire/module.h"

struct impl {
	struct pw_core *core;
	struct pw_properties *properties;

	DBusConnection *bus;

	struct pw_listener global_added;
	struct pw_listener global_removed;

	struct spa_list client_list;

	struct spa_source *dispatch_event;
};

struct client_info {
	struct impl *impl;
	struct spa_list link;
	struct pw_client *client;
	bool is_sandboxed;
	const struct pw_core_methods *old_methods;
	struct pw_core_methods core_methods;
	struct spa_list async_pending;
	struct pw_listener resource_impl;
	struct pw_listener resource_removed;
};

struct async_pending {
	struct spa_list link;
	struct client_info *info;
	bool handled;
	char *handle;
	struct pw_resource *resource;
	char *factory_name;
	char *name;
	struct pw_properties *properties;
	uint32_t version;
	uint32_t new_id;
};

static struct client_info *find_client_info(struct impl *impl, struct pw_client *client)
{
	struct client_info *info;

	spa_list_for_each(info, &impl->client_list, link) {
		if (info->client == client)
			return info;
	}
	return NULL;
}

static void close_request(struct async_pending *p)
{
	DBusMessage *m = NULL;
	struct impl *impl = p->info->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->factory_name);
	free(p->name);
	if (p->properties)
		pw_properties_free(p->properties);
	free(p);
}

static void client_info_free(struct client_info *cinfo)
{
	struct async_pending *p, *tmp;

	spa_list_for_each_safe(p, tmp, &cinfo->async_pending, link)
		free_pending(p);

	spa_list_remove(&cinfo->link);
	free(cinfo);
}

static bool client_is_sandboxed(struct pw_client *cl)
{
	char data[2048], *ptr;
	size_t n, size;
	const char *state = NULL;
	const char *current;
	bool result;
	int fd;
	pid_t pid;

	if (cl->ucred_valid) {
		pw_log_info("client has trusted pid %d", cl->ucred.pid);
	} else {
		pw_log_info("no trusted pid found, assuming not sandboxed\n");
		return false;
	}

	pid = cl->ucred.pid;

	sprintf(data, "/proc/%u/cgroup", pid);
	fd = open(data, O_RDONLY | O_CLOEXEC, 0);
	if (fd == -1)
		return false;

	spa_zero(data);
	size = sizeof(data);
	ptr = data;

	while (size > 0) {
		int r;

		if ((r = read(fd, data, size)) < 0) {
			if (errno == EINTR)
				continue;
			else
				break;
		}
		if (r == 0)
			break;

		ptr += r;
		size -= r;
	}
	close(fd);

	result = false;
	while ((current = pw_split_walk(data, "\n", &n, &state)) != NULL) {
		if (strncmp(current, "1:name=systemd:", strlen("1:name=systemd:")) == 0) {
			const char *p = strstr(current, "flatpak-");
			if (p && p - current < n) {
				pw_log_info("found a flatpak cgroup, assuming sandboxed\n");
				result = true;
				break;
			}
		}
	}
	return result;
}

static bool
check_global_owner(struct pw_core *core, struct pw_client *client, struct pw_global *global)
{
	if (global == NULL)
		return false;

	if (global->owner == NULL)
		return true;

	if (global->owner->client->ucred.uid == client->ucred.uid)
		return true;

	return false;
}

static bool
do_global_filter(struct pw_global *global, struct pw_client *client, void *data)
{
	if (global->type == client->core->type.link) {
		struct pw_link *link = global->object;

		/* we must be able to see both nodes */
		if (link->output
		    && !check_global_owner(client->core, client, link->output->node->global))
			 return false;

		if (link->input
		    && !check_global_owner(client->core, client, link->input->node->global))
			 return false;
	} else if (!check_global_owner(client->core, client, global))
		 return false;

	return true;
}

static DBusHandlerResult
portal_response(DBusConnection *connection, DBusMessage *msg, void *user_data)
{
	struct client_info *cinfo = user_data;

	if (dbus_message_is_signal(msg, "org.freedesktop.portal.Request", "Response")) {
		uint32_t response = 2;
		DBusError error;
		struct async_pending *p;

		dbus_error_init(&error);

		dbus_connection_remove_filter(connection, portal_response, cinfo);

		if (!dbus_message_get_args
		    (msg, &error, DBUS_TYPE_UINT32, &response, DBUS_TYPE_INVALID)) {
			pw_log_error("failed to parse Response: %s", error.message);
			dbus_error_free(&error);
		}

		p = find_pending(cinfo, dbus_message_get_path(msg));
		if (p == NULL)
			return DBUS_HANDLER_RESULT_HANDLED;

		p->handled = true;

		pw_log_debug("portal check result: %d", response);

		if (response == 0) {
			cinfo->old_methods->create_node (p->resource,
							 p->factory_name,
							 p->name,
							 &p->properties->dict,
							 p->version,
							 p->new_id);
		} else {
			pw_core_notify_error(cinfo->client->core_resource,
					     p->resource->id, SPA_RESULT_NO_PERMISSION, "not allowed");

		}
		free_pending(p);
		pw_client_set_busy(cinfo->client, false);

		return DBUS_HANDLER_RESULT_HANDLED;
	}
	return DBUS_HANDLER_RESULT_NOT_YET_HANDLED;
}


static void do_create_node(void *object,
			   const char *factory_name,
			   const char *name,
			   const struct spa_dict *props,
			   uint32_t version,
			   uint32_t new_id)
{
	struct pw_resource *resource = object;
	struct client_info *cinfo = resource->access_private;
	struct impl *impl = cinfo->impl;
	struct pw_client *client = resource->client;
	DBusMessage *m = NULL, *r = NULL;
	DBusError error;
	pid_t pid;
	DBusMessageIter msg_iter;
	DBusMessageIter dict_iter;
	const char *handle;
	const char *device;
	struct async_pending *p;

	if (!cinfo->is_sandboxed) {
		cinfo->old_methods->create_node (object, factory_name, name, props, version, new_id);
		return;
	}
	if (strcmp(factory_name, "client-node") != 0) {
		pw_log_error("can only allow client-node");
		goto not_allowed;
	}

	pw_log_info("ask portal for client %p", cinfo->client);

	dbus_error_init(&error);

	if (!(m = dbus_message_new_method_call("org.freedesktop.portal.Desktop",
					       "/org/freedesktop/portal/desktop",
					       "org.freedesktop.portal.Device", "AccessDevice")))
		goto no_method_call;

	device = "camera";

	pid = cinfo->client->ucred.pid;
	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);
	dbus_message_iter_append_basic(&dict_iter, DBUS_TYPE_STRING, &device);
	dbus_message_iter_close_container(&msg_iter, &dict_iter);

	dbus_message_iter_open_container(&msg_iter, DBUS_TYPE_ARRAY, "{sv}", &dict_iter);
	dbus_message_iter_close_container(&msg_iter, &dict_iter);

	if (!(r = dbus_connection_send_with_reply_and_block(impl->bus, m, -1, &error)))
		goto send_failed;

	dbus_message_unref(m);

	if (!dbus_message_get_args(r, &error, DBUS_TYPE_OBJECT_PATH, &handle, DBUS_TYPE_INVALID))
		goto parse_failed;

	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->info = cinfo;
	p->handle = strdup(handle);
	p->handled = false;
	p->resource = resource;
	p->factory_name = strdup(factory_name);
	p->name = strdup(name);
	p->properties = props ? pw_properties_new_dict(props) : NULL;
	p->version = version;
	p->new_id = new_id;
	pw_client_set_busy(client, true);

	pw_log_debug("pending %p: handle %s", p, handle);
	spa_list_insert(cinfo->async_pending.prev, &p->link);

	return;

      no_method_call:
	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_core_notify_error(client->core_resource,
			     resource->id, SPA_RESULT_NO_PERMISSION, "not allowed");
	return;
}

static void
do_create_link(void *object,
	       uint32_t output_node_id,
	       uint32_t output_port_id,
	       uint32_t input_node_id,
	       uint32_t input_port_id,
	       const struct spa_format *filter,
	       const struct spa_dict *props,
	       uint32_t new_id)
{
	struct pw_resource *resource = object;
	struct client_info *cinfo = resource->access_private;
	struct pw_client *client = resource->client;

	if (cinfo->is_sandboxed) {
		pw_core_notify_error(client->core_resource,
				     resource->id, SPA_RESULT_NO_PERMISSION, "not allowed");
		return;
	}
	cinfo->old_methods->create_link (object,
					 output_node_id,
					 output_port_id,
					 input_node_id,
					 input_port_id,
					 filter,
					 props,
					 new_id);
}

static void on_resource_impl(struct pw_listener *listener,
			     struct pw_client *client,
			     struct pw_resource *resource)
{
	struct client_info *cinfo = SPA_CONTAINER_OF(listener, struct client_info, resource_impl);
	struct impl *impl = cinfo->impl;

	if (resource->type == impl->core->type.core) {
		cinfo->old_methods = resource->implementation;
		cinfo->core_methods = *cinfo->old_methods;
		resource->implementation = &cinfo->core_methods;
		resource->access_private = cinfo;
		cinfo->core_methods.create_node = do_create_node;
		cinfo->core_methods.create_link = do_create_link;
	}
}

static void
on_global_added(struct pw_listener *listener, struct pw_core *core, struct pw_global *global)
{
	struct impl *impl = SPA_CONTAINER_OF(listener, struct impl, global_added);

	if (global->type == impl->core->type.client) {
		struct pw_client *client = global->object;
		struct client_info *cinfo;

		cinfo = calloc(1, sizeof(struct client_info));
		cinfo->impl = impl;
		cinfo->client = client;
		cinfo->is_sandboxed = client_is_sandboxed(client);
		spa_list_init(&cinfo->async_pending);

		pw_signal_add(&client->resource_impl, &cinfo->resource_impl, on_resource_impl);

		spa_list_insert(impl->client_list.prev, &cinfo->link);

		pw_log_debug("module %p: client %p added", impl, client);
	}
}

static void
on_global_removed(struct pw_listener *listener, struct pw_core *core, struct pw_global *global)
{
	struct impl *impl = SPA_CONTAINER_OF(listener, struct impl, global_removed);

	if (global->type == impl->core->type.client) {
		struct pw_client *client = global->object;
		struct client_info *cinfo;

		if ((cinfo = find_client_info(impl, client)))
			client_info_free(cinfo);

		pw_log_debug("module %p: client %p removed", impl, client);
	}
}

static void dispatch_cb(struct spa_loop_utils *utils, struct spa_source *source, void *userdata)
{
	struct impl *impl = userdata;

	if (dbus_connection_dispatch(impl->bus) == DBUS_DISPATCH_COMPLETE)
		pw_loop_enable_idle(impl->core->main_loop, source, false);
}

static void dispatch_status(DBusConnection *conn, DBusDispatchStatus status, void *userdata)
{
	struct impl *impl = userdata;

	pw_loop_enable_idle(impl->core->main_loop,
			    impl->dispatch_event, status == DBUS_DISPATCH_COMPLETE ? false : true);
}

static inline enum spa_io dbus_to_io(DBusWatch *watch)
{
	enum spa_io mask;
	unsigned int flags;

	/* no watch flags for disabled watches */
	if (!dbus_watch_get_enabled(watch))
		return 0;

	flags = dbus_watch_get_flags(watch);
	mask = SPA_IO_HUP | SPA_IO_ERR;

	if (flags & DBUS_WATCH_READABLE)
		mask |= SPA_IO_IN;
	if (flags & DBUS_WATCH_WRITABLE)
		mask |= SPA_IO_OUT;

	return mask;
}

static inline unsigned int io_to_dbus(enum spa_io mask)
{
	unsigned int flags = 0;

	if (mask & SPA_IO_IN)
		flags |= DBUS_WATCH_READABLE;
	if (mask & SPA_IO_OUT)
		flags |= DBUS_WATCH_WRITABLE;
	if (mask & SPA_IO_HUP)
		flags |= DBUS_WATCH_HANGUP;
	if (mask & SPA_IO_ERR)
		flags |= DBUS_WATCH_ERROR;
	return flags;
}

static void
handle_io_event(struct spa_loop_utils *utils,
		struct spa_source *source, int fd, enum spa_io mask, void *userdata)
{
	DBusWatch *watch = userdata;

	if (!dbus_watch_get_enabled(watch)) {
		pw_log_warn("Asked to handle disabled watch: %p %i", (void *) watch, fd);
		return;
	}
	dbus_watch_handle(watch, io_to_dbus(mask));
}

static dbus_bool_t add_watch(DBusWatch *watch, void *userdata)
{
	struct impl *impl = userdata;
	struct spa_source *source;

	pw_log_debug("add watch %p %d", watch, dbus_watch_get_unix_fd(watch));

	/* we dup because dbus tends to add the same fd multiple times and our epoll
	 * implementation does not like that */
	source = pw_loop_add_io(impl->core->main_loop,
				dup(dbus_watch_get_unix_fd(watch)),
				dbus_to_io(watch), true, handle_io_event, watch);

	dbus_watch_set_data(watch, source, NULL);
	return TRUE;
}

static void remove_watch(DBusWatch *watch, void *userdata)
{
	struct impl *impl = userdata;
	struct spa_source *source;

	if ((source = dbus_watch_get_data(watch)))
		pw_loop_destroy_source(impl->core->main_loop, source);
}

static void toggle_watch(DBusWatch *watch, void *userdata)
{
	struct impl *impl = userdata;
	struct spa_source *source;

	source = dbus_watch_get_data(watch);

	pw_loop_update_io(impl->core->main_loop, source, dbus_to_io(watch));
}

static void
handle_timer_event(struct spa_loop_utils *utils, struct spa_source *source, void *userdata)
{
	DBusTimeout *timeout = userdata;
	uint64_t t;
	struct timespec ts;

	if (dbus_timeout_get_enabled(timeout)) {
		t = dbus_timeout_get_interval(timeout) * SPA_NSEC_PER_MSEC;
		ts.tv_sec = t / SPA_NSEC_PER_SEC;
		ts.tv_nsec = t % SPA_NSEC_PER_SEC;
		spa_loop_utils_update_timer(utils, source, &ts, NULL, false);

		dbus_timeout_handle(timeout);
	}
}

static dbus_bool_t add_timeout(DBusTimeout *timeout, void *userdata)
{
	struct impl *impl = userdata;
	struct spa_source *source;
	struct timespec ts;
	uint64_t t;

	if (!dbus_timeout_get_enabled(timeout))
		return FALSE;

	source = pw_loop_add_timer(impl->core->main_loop, handle_timer_event, timeout);

	dbus_timeout_set_data(timeout, source, NULL);

	t = dbus_timeout_get_interval(timeout) * SPA_NSEC_PER_MSEC;
	ts.tv_sec = t / SPA_NSEC_PER_SEC;
	ts.tv_nsec = t % SPA_NSEC_PER_SEC;
	pw_loop_update_timer(impl->core->main_loop, source, &ts, NULL, false);
	return TRUE;
}

static void remove_timeout(DBusTimeout *timeout, void *userdata)
{
	struct impl *impl = userdata;
	struct spa_source *source;

	if ((source = dbus_timeout_get_data(timeout)))
		pw_loop_destroy_source(impl->core->main_loop, source);
}

static void toggle_timeout(DBusTimeout *timeout, void *userdata)
{
	struct impl *impl = userdata;
	struct spa_source *source;
	struct timespec ts, *tsp;

	source = dbus_timeout_get_data(timeout);

	if (dbus_timeout_get_enabled(timeout)) {
		uint64_t t = dbus_timeout_get_interval(timeout) * SPA_NSEC_PER_MSEC;
		ts.tv_sec = t / SPA_NSEC_PER_SEC;
		ts.tv_nsec = t % SPA_NSEC_PER_SEC;
		tsp = &ts;
	} else {
		tsp = NULL;
	}
	pw_loop_update_timer(impl->core->main_loop, source, tsp, NULL, false);
}

static void wakeup_main(void *userdata)
{
	struct impl *impl = userdata;

	pw_loop_enable_idle(impl->core->main_loop, impl->dispatch_event, true);
}

static struct impl *module_new(struct pw_core *core, struct pw_properties *properties)
{
	struct impl *impl;
	DBusError error;

	dbus_error_init(&error);

	impl = calloc(1, sizeof(struct impl));
	pw_log_debug("module %p: new", impl);

	impl->core = core;
	impl->properties = properties;

	impl->bus = dbus_bus_get_private(DBUS_BUS_SESSION, &error);
	if (impl->bus == NULL)
		goto error;

	impl->dispatch_event = pw_loop_add_idle(core->main_loop, false, dispatch_cb, impl);

	dbus_connection_set_exit_on_disconnect(impl->bus, false);
	dbus_connection_set_dispatch_status_function(impl->bus, dispatch_status, impl, NULL);
	dbus_connection_set_watch_functions(impl->bus, add_watch, remove_watch, toggle_watch, impl,
					    NULL);
	dbus_connection_set_timeout_functions(impl->bus, add_timeout, remove_timeout,
					      toggle_timeout, impl, NULL);
	dbus_connection_set_wakeup_main_function(impl->bus, wakeup_main, impl, NULL);

	spa_list_init(&impl->client_list);

	pw_signal_add(&core->global_added, &impl->global_added, on_global_added);
	pw_signal_add(&core->global_removed, &impl->global_removed, on_global_removed);
	core->global_filter = do_global_filter;
	core->global_filter_data = impl;

	return impl;

      error:
	pw_log_error("Failed to connect to system bus: %s", error.message);
	dbus_error_free(&error);
	return NULL;
}

#if 0
static void module_destroy(struct impl *impl)
{
	pw_log_debug("module %p: destroy", impl);

	dbus_connection_close(impl->bus);
	dbus_connection_unref(impl->bus);
	free(impl);
}
#endif

bool pipewire__module_init(struct pw_module *module, const char *args)
{
	module_new(module->core, NULL);
	return true;
}