security-context-v1: new protocol implementation

Co-authored-by: Puck Meerburg <puck@puckipedia.com>
References: https://gitlab.freedesktop.org/wayland/wayland-protocols/-/merge_requests/68

include/wlr/types/wlr_security_context_v1.h

@@ -0,0 +1,48 @@
+/*
+ * This an unstable interface of wlroots. No guarantees are made regarding the
+ * future consistency of this API.
+ */
+#ifndef WLR_USE_UNSTABLE
+#error "Add -DWLR_USE_UNSTABLE to enable unstable wlroots features"
+#endif
+
+#ifndef WLR_TYPES_WLR_SECURITY_CONTEXT_V1_H
+#define WLR_TYPES_WLR_SECURITY_CONTEXT_V1_H
+
+#include <wayland-server-core.h>
+
+/**
+ * An implementation of the security context protocol.
+ *
+ * Compositors can create this manager, setup a filter for Wayland globals via
+ * wl_display_set_global_filter(), and inside the filter query the security
+ * context state via wlr_security_context_manager_v1_lookup_client().
+ */
+struct wlr_security_context_manager_v1 {
+	struct wl_global *global;
+
+	struct {
+		struct wl_signal destroy;
+	} events;
+
+	void *data;
+
+	// private state
+
+	struct wl_list contexts; // wlr_security_context_v1.link
+
+	struct wl_listener display_destroy;
+};
+
+struct wlr_security_context_v1_state {
+	char *sandbox_engine; // may be NULL
+	char *app_id; // may be NULL
+	char *instance_id; // may be NULL
+};
+
+struct wlr_security_context_manager_v1 *wlr_security_context_manager_v1_create(
+	struct wl_display *display);
+const struct wlr_security_context_v1_state *wlr_security_context_manager_v1_lookup_client(
+	struct wlr_security_context_manager_v1 *manager, struct wl_client *client);
+
+#endif

protocol/meson.build

@@ -24,6 +24,7 @@ protocols = {
 	'ext-idle-notify-v1': wl_protocol_dir / 'staging/ext-idle-notify/ext-idle-notify-v1.xml',
 	'ext-session-lock-v1': wl_protocol_dir / 'staging/ext-session-lock/ext-session-lock-v1.xml',
 	'fractional-scale-v1': wl_protocol_dir / 'staging/fractional-scale/fractional-scale-v1.xml',
+	'security-context-v1': wl_protocol_dir / 'staging/security-context/security-context-v1.xml',
 	'single-pixel-buffer-v1': wl_protocol_dir / 'staging/single-pixel-buffer/single-pixel-buffer-v1.xml',
 	'xdg-activation-v1': wl_protocol_dir / 'staging/xdg-activation/xdg-activation-v1.xml',
 	'xwayland-shell-v1': wl_protocol_dir / 'staging/xwayland-shell/xwayland-shell-v1.xml',

types/meson.build

@@ -69,6 +69,7 @@ wlr_files += files(
 	'wlr_region.c',
 	'wlr_relative_pointer_v1.c',
 	'wlr_screencopy_v1.c',
+	'wlr_security_context_v1.c',
 	'wlr_server_decoration.c',
 	'wlr_session_lock_v1.c',
 	'wlr_shm.c',

types/wlr_security_context_v1.c

@@ -0,0 +1,428 @@
+#define _POSIX_C_SOURCE 200809L
+#include <assert.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <wlr/types/wlr_security_context_v1.h>
+#include <wlr/util/log.h>
+#include "security-context-v1-protocol.h"
+
+#define SECURITY_CONTEXT_MANAGER_V1_VERSION 1
+
+struct wlr_security_context_v1 {
+	struct wlr_security_context_manager_v1 *manager;
+	struct wlr_security_context_v1_state state;
+	struct wl_list link; // wlr_security_context_manager_v1.contexts
+	int listen_fd, close_fd;
+	struct wl_event_source *listen_source, *close_source;
+};
+
+struct wlr_security_context_v1_client {
+	struct wlr_security_context_v1_state state;
+	struct wl_listener destroy;
+};
+
+static void resource_handle_destroy(struct wl_client *client,
+		struct wl_resource *resource) {
+	wl_resource_destroy(resource);
+}
+
+static const struct wp_security_context_manager_v1_interface manager_impl;
+static const struct wp_security_context_v1_interface security_context_impl;
+
+static struct wlr_security_context_manager_v1 *manager_from_resource(
+		struct wl_resource *resource) {
+	assert(wl_resource_instance_of(resource,
+		&wp_security_context_manager_v1_interface, &manager_impl));
+	struct wlr_security_context_manager_v1 *manager =
+		wl_resource_get_user_data(resource);
+	assert(manager != NULL);
+	return manager;
+}
+
+/**
+ * Get a struct wlr_security_context_v1 from a struct wl_resource.
+ *
+ * NULL is returned if the security context has been committed.
+ */
+static struct wlr_security_context_v1 *security_context_from_resource(
+		struct wl_resource *resource) {
+	assert(wl_resource_instance_of(resource,
+		&wp_security_context_v1_interface, &security_context_impl));
+	return wl_resource_get_user_data(resource);
+}
+
+static void security_context_state_finish(struct wlr_security_context_v1_state *state) {
+	free(state->app_id);
+	free(state->sandbox_engine);
+	free(state->instance_id);
+}
+
+static bool copy_state_field(char **dst, const char *src) {
+	if (src == NULL) {
+		return true;
+	}
+	*dst = strdup(src);
+	return *dst != NULL;
+}
+
+static bool security_context_state_copy(struct wlr_security_context_v1_state *dst,
+		const struct wlr_security_context_v1_state *src) {
+	bool ok = copy_state_field(&dst->app_id, src->app_id) &&
+		copy_state_field(&dst->sandbox_engine, src->sandbox_engine) &&
+		copy_state_field(&dst->instance_id, src->instance_id);
+	if (!ok) {
+		security_context_state_finish(dst);
+	}
+	return ok;
+}
+
+static void security_context_destroy(
+		struct wlr_security_context_v1 *security_context) {
+	if (security_context == NULL) {
+		return;
+	}
+
+	if (security_context->listen_source != NULL) {
+		wl_event_source_remove(security_context->listen_source);
+	}
+	if (security_context->close_source != NULL) {
+		wl_event_source_remove(security_context->close_source);
+	}
+
+	close(security_context->listen_fd);
+	close(security_context->close_fd);
+
+	security_context_state_finish(&security_context->state);
+	wl_list_remove(&security_context->link);
+	free(security_context);
+}
+
+static void security_context_client_handle_destroy(struct wl_listener *listener,
+		void *data) {
+	struct wlr_security_context_v1_client *security_context_client =
+		wl_container_of(listener, security_context_client, destroy);
+	wl_list_remove(&security_context_client->destroy.link);
+	security_context_state_finish(&security_context_client->state);
+	free(security_context_client);
+}
+
+static int security_context_handle_listen_fd_event(int listen_fd, uint32_t mask,
+		void *data) {
+	struct wlr_security_context_v1 *security_context = data;
+
+	if (mask & (WL_EVENT_HANGUP | WL_EVENT_ERROR)) {
+		security_context_destroy(security_context);
+		return 0;
+	}
+
+	if (mask & WL_EVENT_READABLE) {
+		int client_fd = accept(listen_fd, NULL, NULL);
+		if (client_fd < 0) {
+			wlr_log_errno(WLR_ERROR, "accept failed");
+			return 0;
+		}
+
+		struct wlr_security_context_v1_client *security_context_client =
+			calloc(1, sizeof(*security_context_client));
+		if (security_context_client == NULL) {
+			wlr_log_errno(WLR_ERROR, "Allocation failed");
+			close(client_fd);
+			return 0;
+		}
+
+		struct wl_display *display =
+			wl_global_get_display(security_context->manager->global);
+		struct wl_client *client = wl_client_create(display, client_fd);
+		if (client == NULL) {
+			wlr_log(WLR_ERROR, "wl_client_create failed");
+			close(client_fd);
+			return 0;
+		}
+
+		if (!security_context_state_copy(&security_context_client->state,
+				&security_context->state)) {
+			wl_client_post_no_memory(client);
+			return 0;
+		}
+
+		security_context_client->destroy.notify = security_context_client_handle_destroy;
+		wl_client_add_destroy_listener(client, &security_context_client->destroy);
+	}
+
+	return 0;
+}
+
+static int security_context_handle_close_fd_event(int fd, uint32_t mask,
+		void *data) {
+	struct wlr_security_context_v1 *security_context = data;
+
+	if (mask & (WL_EVENT_HANGUP | WL_EVENT_ERROR)) {
+		security_context_destroy(security_context);
+	}
+
+	return 0;
+}
+
+static void security_context_handle_commit(struct wl_client *client,
+		struct wl_resource *resource) {
+	struct wlr_security_context_v1 *security_context =
+		security_context_from_resource(resource);
+	if (security_context == NULL) {
+		wl_resource_post_error(resource,
+			WP_SECURITY_CONTEXT_V1_ERROR_ALREADY_USED,
+			"Security context has already been committed");
+		return;
+	}
+
+	// In theory the compositor should prevent this with a global filter, but
+	// let's make sure it doesn't happen.
+	if (wlr_security_context_manager_v1_lookup_client(security_context->manager,
+			client) != NULL) {
+		wl_resource_post_error(resource,
+			WP_SECURITY_CONTEXT_MANAGER_V1_ERROR_NESTED,
+			"Nested security contexts are forbidden");
+		return;
+	}
+
+	struct wl_display *display = wl_client_get_display(client);
+	struct wl_event_loop *loop = wl_display_get_event_loop(display);
+
+	security_context->listen_source = wl_event_loop_add_fd(loop,
+		security_context->listen_fd, WL_EVENT_READABLE,
+		security_context_handle_listen_fd_event, security_context);
+	if (security_context->listen_source == NULL) {
+		wl_resource_post_no_memory(resource);
+		return;
+	}
+
+	security_context->close_source = wl_event_loop_add_fd(loop,
+		security_context->close_fd, 0, security_context_handle_close_fd_event,
+		security_context);
+	if (security_context->close_source == NULL) {
+		wl_resource_post_no_memory(resource);
+		return;
+	}
+
+	wl_resource_set_user_data(resource, NULL);
+}
+
+static void security_context_handle_set_sandbox_engine(struct wl_client *client,
+		struct wl_resource *resource, const char *sandbox_engine) {
+	struct wlr_security_context_v1 *security_context =
+		security_context_from_resource(resource);
+	if (security_context == NULL) {
+		wl_resource_post_error(resource,
+			WP_SECURITY_CONTEXT_V1_ERROR_ALREADY_USED,
+			"Security context has already been committed");
+		return;
+	}
+
+	if (security_context->state.sandbox_engine != NULL) {
+		wl_resource_post_error(resource,
+			WP_SECURITY_CONTEXT_V1_ERROR_ALREADY_SET,
+			"Sandbox engine has already been set");
+		return;
+	}
+
+	security_context->state.sandbox_engine = strdup(sandbox_engine);
+	if (security_context->state.sandbox_engine == NULL) {
+		wl_resource_post_no_memory(resource);
+	}
+}
+
+static void security_context_handle_set_app_id(struct wl_client *client,
+		struct wl_resource *resource, const char *app_id) {
+	struct wlr_security_context_v1 *security_context =
+		security_context_from_resource(resource);
+	if (security_context == NULL) {
+		wl_resource_post_error(resource,
+			WP_SECURITY_CONTEXT_V1_ERROR_ALREADY_USED,
+			"Security context has already been committed");
+		return;
+	}
+
+	if (security_context->state.app_id != NULL) {
+		wl_resource_post_error(resource,
+			WP_SECURITY_CONTEXT_V1_ERROR_ALREADY_SET,
+			"App ID has already been set");
+		return;
+	}
+
+	security_context->state.app_id = strdup(app_id);
+	if (security_context->state.app_id == NULL) {
+		wl_resource_post_no_memory(resource);
+	}
+}
+
+static void security_context_handle_set_instance_id(struct wl_client *client,
+		struct wl_resource *resource, const char *instance_id) {
+	struct wlr_security_context_v1 *security_context =
+		security_context_from_resource(resource);
+	if (security_context == NULL) {
+		wl_resource_post_error(resource,
+			WP_SECURITY_CONTEXT_V1_ERROR_ALREADY_USED,
+			"Security context has already been committed");
+		return;
+	}
+
+	if (security_context->state.instance_id != NULL) {
+		wl_resource_post_error(resource,
+			WP_SECURITY_CONTEXT_V1_ERROR_ALREADY_SET,
+			"Instance ID has already been set");
+		return;
+	}
+
+	security_context->state.instance_id = strdup(instance_id);
+	if (security_context->state.instance_id == NULL) {
+		wl_resource_post_no_memory(resource);
+	}
+}
+
+static const struct wp_security_context_v1_interface security_context_impl = {
+	.destroy = resource_handle_destroy,
+	.commit = security_context_handle_commit,
+	.set_sandbox_engine = security_context_handle_set_sandbox_engine,
+	.set_app_id = security_context_handle_set_app_id,
+	.set_instance_id = security_context_handle_set_instance_id,
+};
+
+static void security_context_resource_destroy(struct wl_resource *resource) {
+	struct wlr_security_context_v1 *security_context =
+		security_context_from_resource(resource);
+	security_context_destroy(security_context);
+}
+
+static void manager_handle_create_listener(struct wl_client *client,
+		struct wl_resource *manager_resource, uint32_t id,
+		int listen_fd, int close_fd) {
+	struct wlr_security_context_manager_v1 *manager =
+		manager_from_resource(manager_resource);
+
+	struct stat stat_buf = {0};
+	if (fstat(listen_fd, &stat_buf) != 0) {
+		wlr_log_errno(WLR_ERROR, "fstat failed on listen FD");
+		wl_resource_post_error(manager_resource,
+			WP_SECURITY_CONTEXT_MANAGER_V1_ERROR_INVALID_LISTEN_FD,
+			"Invalid listen_fd");
+		return;
+	} else if (!S_ISSOCK(stat_buf.st_mode)) {
+		wl_resource_post_error(manager_resource,
+			WP_SECURITY_CONTEXT_MANAGER_V1_ERROR_INVALID_LISTEN_FD,
+			"listen_fd is not a socket");
+		return;
+	}
+
+	int accept_conn = 0;
+	socklen_t accept_conn_size = sizeof(accept_conn);
+	if (getsockopt(listen_fd, SOL_SOCKET, SO_ACCEPTCONN, &accept_conn,
+			&accept_conn_size) != 0) {
+		wlr_log_errno(WLR_ERROR, "getsockopt failed on listen FD");
+		wl_resource_post_error(manager_resource,
+			WP_SECURITY_CONTEXT_MANAGER_V1_ERROR_INVALID_LISTEN_FD,
+			"Invalid listen_fd");
+		return;
+	} else if (accept_conn == 0) {
+		wl_resource_post_error(manager_resource,
+			WP_SECURITY_CONTEXT_MANAGER_V1_ERROR_INVALID_LISTEN_FD,
+			"listen_fd is not a listening socket");
+		return;
+	}
+
+	struct wlr_security_context_v1 *security_context =
+		calloc(1, sizeof(*security_context));
+	if (security_context == NULL) {
+		wl_resource_post_no_memory(manager_resource);
+		return;
+	}
+
+	security_context->manager = manager;
+	security_context->listen_fd = listen_fd;
+	security_context->close_fd = close_fd;
+
+	uint32_t version = wl_resource_get_version(manager_resource);
+	struct wl_resource *resource = wl_resource_create(client,
+		&wp_security_context_v1_interface, version, id);
+	if (resource == NULL) {
+		free(security_context);
+		wl_resource_post_no_memory(manager_resource);
+		return;
+	}
+	wl_resource_set_implementation(resource, &security_context_impl,
+		security_context, security_context_resource_destroy);
+
+	wl_list_insert(&manager->contexts, &security_context->link);
+}
+
+static const struct wp_security_context_manager_v1_interface manager_impl = {
+	.destroy = resource_handle_destroy,
+	.create_listener = manager_handle_create_listener,
+};
+
+static void manager_bind(struct wl_client *client, void *data,
+		uint32_t version, uint32_t id) {
+	struct wlr_security_context_manager_v1 *manager = data;
+
+	struct wl_resource *resource = wl_resource_create(client,
+		&wp_security_context_manager_v1_interface, version, id);
+	if (resource == NULL) {
+		wl_client_post_no_memory(client);
+		return;
+	}
+	wl_resource_set_implementation(resource, &manager_impl, manager, NULL);
+}
+
+static void handle_display_destroy(struct wl_listener *listener, void *data) {
+	struct wlr_security_context_manager_v1 *manager =
+		wl_container_of(listener, manager, display_destroy);
+	wl_signal_emit_mutable(&manager->events.destroy, manager);
+	assert(wl_list_empty(&manager->events.destroy.listener_list));
+
+	struct wlr_security_context_v1 *security_context, *tmp;
+	wl_list_for_each_safe(security_context, tmp, &manager->contexts, link) {
+		security_context_destroy(security_context);
+	}
+
+	wl_global_destroy(manager->global);
+	wl_list_remove(&manager->display_destroy.link);
+	free(manager);
+}
+
+struct wlr_security_context_manager_v1 *wlr_security_context_manager_v1_create(
+		struct wl_display *display) {
+	struct wlr_security_context_manager_v1 *manager = calloc(1, sizeof(*manager));
+	if (manager == NULL) {
+		return NULL;
+	}
+
+	manager->global = wl_global_create(display,
+		&wp_security_context_manager_v1_interface,
+		SECURITY_CONTEXT_MANAGER_V1_VERSION, manager, manager_bind);
+	if (manager->global == NULL) {
+		free(manager);
+		return NULL;
+	}
+
+	wl_list_init(&manager->contexts);
+	wl_signal_init(&manager->events.destroy);
+
+	manager->display_destroy.notify = handle_display_destroy;
+	wl_display_add_destroy_listener(display, &manager->display_destroy);
+
+	return manager;
+}
+
+const struct wlr_security_context_v1_state *wlr_security_context_manager_v1_lookup_client(
+		struct wlr_security_context_manager_v1 *manager, struct wl_client *client) {
+	struct wl_listener *listener = wl_client_get_destroy_listener(client,
+		security_context_client_handle_destroy);
+	if (listener == NULL) {
+		return NULL;
+	}
+
+	struct wlr_security_context_v1_client *security_context_client =
+		wl_container_of(listener, security_context_client, destroy);
+	return &security_context_client->state;
+}