[PATCH v5 1/3] wayland-server: Add API to control globals visibility
Yong Bakos
junk at humanoriented.com
Tue Oct 18 15:54:36 UTC 2016
On Oct 18, 2016, at 7:23 AM, Olivier Fourdan <ofourdan at redhat.com> wrote:
>
> Add a new API to let compositor decide whether or not a wl_global
> should be advertised to the clients via wl_registry_bind() or
> display_get_registry()
>
> By using its own filter, the compositor can decide which wl_global would
> be listed to clients.
>
> Compositors can use this mechanism to hide their own private interfaces
> that regular clients should not use.
>
> - Hiding interfaces that expose compositor implementation details
> makes it harder for clients to identify the compositor. Therefore
> clients are a little less likely to develop compositor-specific
> workarounds instead of reporting problems upstream.
>
> - Hiding can be used to diminish the problems from missing namespacing:
> if two compositors happen to use the same named global with
> different interfaces for their special-purpose clients, the client
> expecting the different interface would probably never see it
> advertised.
>
> Signed-off-by: Olivier Fourdan <ofourdan at redhat.com>
> Reviewed-by: Jonas Ådahl <jadahl at gmail.com>
> Reviewed-by: Yong Bakos <ybakos at humanoriented.com>
> Acked-by: Pekka Paalanen <pekka.paalanen at collabora.co.uk>
This v remains
Reviewed-by: Yong Bakos <ybakos at humanoriented.com>
yong
> ---
> v2: Follow-up on Jonas' comments on v1:
> Add global's data as user data in callback filter function
> Pass wl_global instead of wl_interface in callback filter function
> Add wl_global_get_interface() to retrieve the wl_interface from the
> given wl_global
> Post an error if a client tries to bind a global which is filtered
> out.
> v3: Follow-up on Jonas' comments on v2:
> Separate from the other wl_global and test additions
> Add its own user data to the global filter
> Rephrase the API doc
> Other few small changes
> v4: Follow-up on Yong's comments on v3:
> Rename wl_display_filter_global_func_t as wl_display_global_filter_func_t
> Document wl_display_global_filter_func_t
> Rename wl_display_set_filter_global as wl_display_set_global_filter
> Rename filter_global() as wl_global_is_visible() and add a short
> explanation in the code
> v5: Rebase against current git master, amend commit message as per
> Pekka's comment and add Pekka's acked-by
>
> src/wayland-server-core.h | 25 ++++++++++++++++++
> src/wayland-server.c | 67 +++++++++++++++++++++++++++++++++++++++++++----
> 2 files changed, 87 insertions(+), 5 deletions(-)
>
> diff --git a/src/wayland-server-core.h b/src/wayland-server-core.h
> index 2c215e4..9ae51dc 100644
> --- a/src/wayland-server-core.h
> +++ b/src/wayland-server-core.h
> @@ -28,6 +28,7 @@
>
> #include <sys/types.h>
> #include <stdint.h>
> +#include <stdbool.h>
> #include "wayland-util.h"
> #include "wayland-version.h"
>
> @@ -168,6 +169,30 @@ wl_global_create(struct wl_display *display,
> void
> wl_global_destroy(struct wl_global *global);
>
> +/** A filter function for wl_global objects
> + *
> + * \param client The client object
> + * \param global The global object to show or hide
> + * \param data The user data pointer
> + *
> + * A filter function enables the server to decide which globals to
> + * advertise to each client.
> + *
> + * When a wl_global filter is set, the given callback funtion will be
> + * called during wl_global advertisment and binding.
> + *
> + * This function should return true if the global object should be made
> + * visible to the client or false otherwise.
> + */
> +typedef bool (*wl_display_global_filter_func_t)(const struct wl_client *client,
> + const struct wl_global *global,
> + void *data);
> +
> +void
> +wl_display_set_global_filter(struct wl_display *display,
> + wl_display_global_filter_func_t filter,
> + void *data);
> +
> struct wl_client *
> wl_client_create(struct wl_display *display, int fd);
>
> diff --git a/src/wayland-server.c b/src/wayland-server.c
> index 9d7d9c1..893bb56 100644
> --- a/src/wayland-server.c
> +++ b/src/wayland-server.c
> @@ -101,6 +101,9 @@ struct wl_display {
> struct wl_signal create_client_signal;
>
> struct wl_array additional_shm_formats;
> +
> + wl_display_global_filter_func_t global_filter;
> + void *global_filter_data;
> };
>
> struct wl_global {
> @@ -769,6 +772,21 @@ wl_client_destroy(struct wl_client *client)
> free(client);
> }
>
> +/* Check if a global filter is registered and use it if any.
> + *
> + * If no wl_global filter has been registered, this funtion will
> + * return true, allowing the wl_global to be visible to the wl_client
> + */
> +static bool
> +wl_global_is_visible(const struct wl_client *client,
> + const struct wl_global *global)
> +{
> + struct wl_display *display = client->display;
> +
> + return (display->global_filter == NULL ||
> + display->global_filter(client, global, display->global_filter_data));
> +}
> +
> static void
> registry_bind(struct wl_client *client,
> struct wl_resource *resource, uint32_t name,
> @@ -795,6 +813,10 @@ registry_bind(struct wl_client *client,
> WL_DISPLAY_ERROR_INVALID_OBJECT,
> "invalid version for global %s (%d): have %d, wanted %d",
> interface, name, global->version, version);
> + else if (!wl_global_is_visible(client, global))
> + wl_resource_post_error(resource,
> + WL_DISPLAY_ERROR_INVALID_OBJECT,
> + "invalid global %s (%d)", interface, name);
> else
> global->bind(client, global->data, version, id);
> }
> @@ -850,11 +872,12 @@ display_get_registry(struct wl_client *client,
> ®istry_resource->link);
>
> wl_list_for_each(global, &display->global_list, link)
> - wl_resource_post_event(registry_resource,
> - WL_REGISTRY_GLOBAL,
> - global->name,
> - global->interface->name,
> - global->version);
> + if (wl_global_is_visible(client, global))
> + wl_resource_post_event(registry_resource,
> + WL_REGISTRY_GLOBAL,
> + global->name,
> + global->interface->name,
> + global->version);
> }
>
> static const struct wl_display_interface display_interface = {
> @@ -925,6 +948,9 @@ wl_display_create(void)
> display->id = 1;
> display->serial = 0;
>
> + display->global_filter = NULL;
> + display->global_filter_data = NULL;
> +
> wl_array_init(&display->additional_shm_formats);
>
> return display;
> @@ -999,6 +1025,37 @@ wl_display_destroy(struct wl_display *display)
> free(display);
> }
>
> +/** Set a filter function for global objects
> + *
> + * \param display The Wayland display object.
> + * \param filter The global filter funtion.
> + * \param data User data to be associated with the global filter.
> + * \return None.
> + *
> + * Set a filter for the wl_display to advertise or hide global objects
> + * to clients.
> + * The set filter will be used during wl_global advertisment to
> + * determine whether a global object should be advertised to a
> + * given client, and during wl_global binding to determine whether
> + * a given client should be allowed to bind to a global.
> + *
> + * Clients that try to bind to a global that was filtered out will
> + * have an error raised.
> + *
> + * Setting the filter NULL will result in all globals being
> + * advertised to all clients. The default is no filter.
> + *
> + * \memberof wl_display
> + */
> +WL_EXPORT void
> +wl_display_set_global_filter(struct wl_display *display,
> + wl_display_global_filter_func_t filter,
> + void *data)
> +{
> + display->global_filter = filter;
> + display->global_filter_data = data;
> +}
> +
> WL_EXPORT struct wl_global *
> wl_global_create(struct wl_display *display,
> const struct wl_interface *interface, int version,
> --
> 2.9.3
>
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