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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | LINKING | SEE ALSO | COLOPHON |
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KEYCTL_...RMISSION(3) Linux Key Management Calls KEYCTL_...RMISSION(3)
keyctl_watch_key - Watch for changes to a key
#include <keyutils.h>
long keyctl_watch_key(key_serial_t key,
int watch_queue_fd
int watch_id);
keyctl_watch_key() sets or removes a watch on key.
watch_id specifies the ID for a watch that will be included in
notification messages. It can be between 0 and 255 to add a key;
it should be -1 to remove a key.
watch_queue_fd is a file descriptor attached to a watch_queue
device instance. Multiple openings of a device provide separate
instances. Each device instance can only have one watch on any
particular key.
Notification Record
Key-specific notification messages that the kernel emits into the
buffer have the following format:
struct key_notification {
struct watch_notification watch;
__u32 key_id;
__u32 aux;
};
The watch.type field will be set to WATCH_TYPE_KEY_NOTIFY and the
watch.subtype field will contain one of the following constants,
indicating the event that occurred and the watch_id passed to
keyctl_watch_key() will be placed in watch.info in the ID field.
The following events are defined:
NOTIFY_KEY_INSTANTIATED
This indicates that a watched key got instantiated or
negatively instantiated. key_id indicates the key that
was instantiated and aux is unused.
NOTIFY_KEY_UPDATED
This indicates that a watched key got updated or
instantiated by update. key_id indicates the key that was
updated and aux is unused.
NOTIFY_KEY_LINKED
This indicates that a key got linked into a watched
keyring. key_id indicates the keyring that was modified
aux indicates the key that was added.
NOTIFY_KEY_UNLINKED
This indicates that a key got unlinked from a watched
keyring. key_id indicates the keyring that was modified
aux indicates the key that was removed.
NOTIFY_KEY_CLEARED
This indicates that a watched keyring got cleared. key_id
indicates the keyring that was cleared and aux is unused.
NOTIFY_KEY_REVOKED
This indicates that a watched key got revoked. key_id
indicates the key that was revoked and aux is unused.
NOTIFY_KEY_INVALIDATED
This indicates that a watched key got invalidated. key_id
indicates the key that was invalidated and aux is unused.
NOTIFY_KEY_SETATTR
This indicates that a watched key had its attributes
(owner, group, permissions, timeout) modified. key_id
indicates the key that was modified and aux is unused.
Removal Notification
When a watched key is garbage collected, all of its watches are
automatically destroyed and a notification is delivered to each
watcher. This will normally be an extended notification of the
form:
struct watch_notification_removal {
struct watch_notification watch;
__u64 id;
};
The watch.type field will be set to WATCH_TYPE_META and the
watch.subtype field will contain WATCH_META_REMOVAL_NOTIFICATION.
If the extended notification is given, then the length will be 2
units, otherwise it will be 1 and only the header will be
present.
The watch_id passed to keyctl_watch_key() will be placed in
watch.info in the ID field.
If the extension is present, id will be set to the ID of the
destroyed key.
On success keyctl_watch_key() returns 0 . On error, the value -1
will be returned and errno will have been set to an appropriate
error.
ENOKEY The specified key does not exist.
EKEYEXPIRED
The specified key has expired.
EKEYREVOKED
The specified key has been revoked.
EACCES The named key exists, but does not grant view permission
to the calling process.
EBUSY The specified key already has a watch on it for that
device instance (add only).
EBADSLT
The specified key doesn't have a watch on it (removal
only).
This is a library function that can be found in libkeyutils.
When linking, -lkeyutils should be specified to the linker.
keyctl(1), add_key(2), keyctl(2), request_key(2), keyctl(3),
keyrings(7), keyutils(7)
This page is part of the keyutils (key management utilities)
project. Information about the project can be found at [unknown
-- if you know, please contact man-pages@man7.org] If you have a
bug report for this manual page, send it to
keyrings@linux-nfs.org. This page was obtained from the
project's upstream Git repository
⟨http://git.kernel.org/pub/scm/linux/kernel/git/dhowells/keyutils.git⟩
on 2024-06-14. (At that time, the date of the most recent commit
that was found in the repository was 2023-03-20.) If you
discover any rendering problems in this HTML version of the page,
or you believe there is a better or more up-to-date source for
the page, or you have corrections or improvements to the
information in this COLOPHON (which is not part of the original
manual page), send a mail to man-pages@man7.org
Linux 28 Aug 2019 KEYCTL_...RMISSION(3)
Pages that refer to this page: keyctl(3)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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