Description of problem:
In order to address issues with file-based Kerberos credential caches, we should enhance the kernel keyring interface to support newer functionality. Based on discussions between Simo, Nalin, David and myself, we propose the following behavior:

1) We will add a new key type "big_key" that allows us to create keys up to 1MiB in size, backed by internal kernel tmpfs, allowing the contents to be swapped out to disk (unlike most other keyrings, which remain in unswappable kernel memory).

2) We will create a new public interface, keyctl_get_krbcache(uid_t, key_serial_t id). This API will allow the user (and certain privileged root processes such as rpc.gssd and gss-proxy) to access the keys for a particular UID. This keyring shall not be tied to a session (so it can outlive a user on the system if they need to perform actions while not logged in, such as access to secure NFS). The kernel keyring should be created automatically on the first request if it does not yet exist. It must also be possible to manipulate the lifetime timer with functions like keyctl_set_timeout() (to align the keyring life with the credential validity) and must also be possible to be destroyed immediately using the usual keyctl APIs (such as in the kdestroy case).


Version-Release number of selected component (if applicable):
keyutils-1.5.6-1.fc20