Hi, I need to store some crypto keys in the kernel where each key is related to a path on the disk. A restricted set of users can create files on such a path but the crypto keys are shared by all such user. I am thinking of using linux kernel key management facilities for my project. I have a usermode application that manages key and a kernel module. However the add_key interface is not clear to me. How do I create a global keyring that is accessible to everyone? Man page of add_key has this to say about add_key -----------------------8<------------------------------------8<---------------------- key_serial_t add_key(const char *type, const char *description, const void *payload, size_t plen, key_serial_t keyring); DESCRIPTION add_key() asks the kernel to create or update a key of the given type and description, Instantiate it with the payload of length plen, and to attach it to the nominated keyring and to return its serial number. The destination keyring serial number may be that of a valid keyring to which the caller has write permission, or it may be a special keyring ID: KEY_SPEC_THREAD_KEYRING This specifies the caller's thread-specific keyring. KEY_SPEC_PROCESS_KEYRING This specifies the caller's process-specific keyring. KEY_SPEC_SESSION_KEYRING This specifies the caller's session-specific keyring. KEY_SPEC_USER_KEYRING This specifies the caller's UID-specific keyring. KEY_SPEC_USER_SESSION_KEYRING This specifies the caller's UID-session keyring. -----------------------8<------------------------------------8<---------------------- I understand that I may need to register my own "type" in the kernel using register_key_type API in the kernel. However I do not understand what value should be passed to the keyring parameter. Also what is meant by possessor in assigning permissions? Also what should be passed to uid and gid parameters in the call to kernel API key_alloc() -- Regards, Ranjan