From f7e47677e39a03057dcced2016c92a9c868693ec Mon Sep 17 00:00:00 2001 From: David Howells Date: Tue, 14 Jan 2020 17:07:11 +0000 Subject: watch_queue: Add a key/keyring notification facility 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: pipe2(fds, O_NOTIFICATION_PIPE); ioctl(fds[1], IOC_WATCH_QUEUE_SET_SIZE, 256); 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(fds[1], IOC_WATCH_QUEUE_SET_FILTER, &filter); keyctl_watch_key(KEY_SPEC_SESSION_KEYRING, fds[1], 0x01); After that, records will be placed into the queue when events occur in which keys are changed in some way. Records are of the following format: struct key_notification { struct watch_notification watch; __u32 key_id; __u32 aux; } *n; Where: n->watch.type will be WATCH_TYPE_KEY_NOTIFY. n->watch.subtype will indicate the type of event, such as NOTIFY_KEY_REVOKED. n->watch.info & WATCH_INFO_LENGTH will indicate the length of the record. n->watch.info & WATCH_INFO_ID will be the second argument to keyctl_watch_key(), shifted. n->key will be the ID of the affected key. n->aux will hold subtype-dependent information, such as the key being linked into the keyring specified by n->key in the case of NOTIFY_KEY_LINKED. Note that it is permissible for event records to be of variable length - or, at least, the length may be dependent on the subtype. Note also that the queue can be shared between multiple notifications of various types. Signed-off-by: David Howells Reviewed-by: James Morris --- security/keys/Kconfig | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'security/keys/Kconfig') diff --git a/security/keys/Kconfig b/security/keys/Kconfig index 47c041563d41..d4dc5ea208af 100644 --- a/security/keys/Kconfig +++ b/security/keys/Kconfig @@ -116,3 +116,12 @@ config KEY_DH_OPERATIONS in the kernel. If you are unsure as to whether this is required, answer N. + +config KEY_NOTIFICATIONS + bool "Provide key/keyring change notifications" + depends on KEYS && WATCH_QUEUE + help + This option provides support for getting change notifications on keys + and keyrings on which the caller has View permission. This makes use + of the /dev/watch_queue misc device to handle the notification + buffer and provides KEYCTL_WATCH_KEY to enable/disable watches. -- cgit v1.2.3-59-g8ed1b