[PATCH 06/13] keys: Add a notification facility [ver #4]

[Jonathan Corbet]

On Fri, 07 Jun 2019 15:18:19 +0100
David Howells <dhowells at redhat.com> wrote:

> Add a key/keyring change notification facility whereby notifications about
> changes in key and keyring content and attributes can be received.
> 
> Firstly, an event queue needs to be created:
> 
> 	fd = open("/dev/event_queue", O_RDWR);
> 	ioctl(fd, IOC_WATCH_QUEUE_SET_SIZE, page_size << n);
> 
> then a notification can be set up to report notifications via that queue:
> 
> 	struct watch_notification_filter filter = {
> 		.nr_filters = 1,
> 		.filters = {
> 			[0] = {
> 				.type = WATCH_TYPE_KEY_NOTIFY,
> 				.subtype_filter[0] = UINT_MAX,
> 			},
> 		},
> 	};
> 	ioctl(fd, IOC_WATCH_QUEUE_SET_FILTER, &filter);
> 	keyctl_watch_key(KEY_SPEC_SESSION_KEYRING, fd, 0x01);

One little nit: it seems that keyctl_watch_key is actually spelled
keyctl(KEYCTL_WATCH_KEY, ...).

jon