Module Nn_datanode_ctrl

module Nn_datanode_ctrl: sig .. end

Manage tickets and push ticket secrets to the datanodes

---

val reset : unit -> unit

type ticket_verifier = {

	tv_safetrans_id : int64;
	tv_safetrans_tmo : int64;
	tv_safetrans_sec : int64;
	tv_datanodes : int list;
	mutable tv_enabled : bool;

}

val new_ticket_verifier : unit -> ticket_verifier

val enable_ticket_verifier_e : ticket_verifier -> unit Uq_engines.engine

val disable_ticket_verifier : ticket_verifier -> (unit -> unit) -> unit

val disconnect : int -> unit

val post_start_hook : Netmcore.res_id -> Pfs_auth.client_auth -> unit

Note that disable_ticket_verifier does not disable the verifier immediately, but delays this to the next round of housekeeping - which usually happens once every second.

There is a security risk here: The verifier remains valid even after the transaction is closed. Although this is only for a very short period of time, this can be abused by a malicious user.

This problem is handled in this way: The verifier can be used to access blocks. There is no problem when only the blocks are accessed for which the ticket was originally valid, i.e. the blocks of the accessed files. The security hole exists only when these blocks are reused for other files - the verifier would then grant access to these other files although there is actually no permission.

So the idea is to prevent that blocks are reused for other files until the verifier is really cancelled. We already have a mechanism - the blocks need to be pinned in the blockmaps (method pin). Such blocks are not freed as long as the pinning remains.

The Nn_blockmap module has been changed so that the pinning remains intact even when a commit or rollback occurs. First when the special release method is called the pinning is revoked. We do this now right after the cancellation of the ticket, using the f_post callback of Nn_datanode_ctrl.disable_ticket_verifier.

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