From: Eric Biggers
Date: Tue Jul 09 2019 - 16:42:29 EST

On Thu, May 23, 2019 at 04:58:43PM +0100, David Howells wrote:
> Provide a keyctl() operation to grant/remove permissions. The grant
> operation, wrapped by libkeyutils, looks like:
> int ret = keyctl_grant_permission(key_serial_t key,
> enum key_ace_subject_type type,
> unsigned int subject,
> unsigned int perm);
> Where key is the key to be modified, type and subject represent the subject
> to which permission is to be granted (or removed) and perm is the set of
> permissions to be granted. 0 is returned on success. SET_SECURITY
> permission is required for this.
> The subject type currently must be KEY_ACE_SUBJ_STANDARD for the moment
> (other subject types will come along later).
> For subject type KEY_ACE_SUBJ_STANDARD, the following subject values are
> available:
> KEY_ACE_POSSESSOR The possessor of the key
> KEY_ACE_OWNER The owner of the key
> KEY_ACE_GROUP The key's group
> perm lists the permissions to be granted:
> KEY_ACE_VIEW Can view the key metadata
> KEY_ACE_READ Can read the key content
> KEY_ACE_WRITE Can update/modify the key content
> KEY_ACE_SEARCH Can find the key by searching/requesting
> KEY_ACE_LINK Can make a link to the key
> KEY_ACE_SET_SECURITY Can set security
> KEY_ACE_INVAL Can invalidate
> KEY_ACE_REVOKE Can revoke
> KEY_ACE_JOIN Can join this keyring
> KEY_ACE_CLEAR Can clear this keyring
> If an ACE already exists for the subject, then the permissions mask will be
> overwritten; if perm is 0, it will be deleted.
> Currently, the internal ACL is limited to a maximum of 16 entries.
> For example:
> int ret = keyctl_grant_permission(key,
> Signed-off-by: David Howells <dhowells@xxxxxxxxxx>

Where is the documentation and tests for this? I want to add syzkaller
definitions for this, but there is no documentation (a commit message doesn't
count). I checked the 'next' branch of keyutils as well.

How is anyone supposed to use this if there is no documentation?

- Eric