[PATCH weston] introduces a setting to give permission to any client to do screenshots

[Bryce W. Harrington]

On Wed, Dec 04, 2013 at 05:38:23PM +0100, Sebastian Wick wrote:
> This patch adds a screenshooter section with the "restrict-access"
> setting which is on by default and is the current behavior of weston.
> When turning it off, all clients can use the screenshooter protocol.
> This makes screen capturing for clients easier because they don't
> have to be started by weston.
> ---
>  man/weston.ini.man  | 6 ++++++
>  src/screenshooter.c | 8 +++++++-
>  weston.ini.in       | 3 +++
>  3 files changed, 16 insertions(+), 1 deletion(-)
> 
> diff --git a/man/weston.ini.man b/man/weston.ini.man
> index 6be90bf..b94ac3d 100644
> --- a/man/weston.ini.man
> +++ b/man/weston.ini.man
> @@ -408,6 +408,12 @@ The terminal shell (string). Sets the $TERM variable.
>  sets the path to the xserver to run (string).
>  .RE
>  .RE
> +.SH "SCREENSHOOTER SECTION"
> +.TP 7
> +.BI "restrict-access=" true
> +only allow authenticated clients to take screenshots (boolean).
> +.RE
> +.RE
>  .SH "SEE ALSO"
>  .BR weston (1),
>  .BR weston-launch (1),
> diff --git a/src/screenshooter.c b/src/screenshooter.c
> index 0c657bc..65b6c09 100644
> --- a/src/screenshooter.c
> +++ b/src/screenshooter.c
> @@ -224,11 +224,17 @@ bind_shooter(struct wl_client *client,
>  {
>  	struct screenshooter *shooter = data;
>  	struct wl_resource *resource;
> +	struct weston_config_section *section;
> +	int restrict_access;
>  
>  	resource = wl_resource_create(client,
>  				      &screenshooter_interface, 1, id);
>  
> -	if (client != shooter->client) {
> +	section = weston_config_get_section(shooter->ec->config, "screenshooter", NULL, NULL);
> +	weston_config_section_get_bool(section,
> +				"restrict-access", &restrict_access, 1);

Could also check the return value of weston_config_section_get_bool;
it'll set errno and return -1 if the config value was typo'd or
omitted.

But does this have security implications?  I assume it is restricted by
default in order to prevent clients from snooping.  Could you add a bit
more detail about the specific problem(s) being solved with this?  Maybe
there's a way to solve the problem without fully dropping the
restriction?

> +
> +	if (restrict_access && client != shooter->client) {
>  		wl_resource_post_error(resource, WL_DISPLAY_ERROR_INVALID_OBJECT,
>  				       "screenshooter failed: permission denied");
>  		wl_resource_destroy(resource);
> diff --git a/weston.ini.in b/weston.ini.in
> index 5181a9e..bc32567 100644
> --- a/weston.ini.in
> +++ b/weston.ini.in
> @@ -65,3 +65,6 @@ path=@libexecdir@/weston-keyboard
>  #constant_accel_factor = 50
>  #min_accel_factor = 0.16
>  #max_accel_factor = 1.0
> +
> +#[screenshooter]
> +#restrict-access=false


Bryce