linux/security/integrity/ima/ima_queue_keys.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * Copyright (C) 2019 Microsoft Corporation
 *
 * Author: Lakshmi Ramasubramanian ([email protected])
 *
 * File: ima_queue_keys.c
 *       Enables deferred processing of keys
 */

#include <linux/user_namespace.h>
#include <linux/workqueue.h>
#include <keys/asymmetric-type.h>
#include "ima.h"

/*
 * Flag to indicate whether a key can be processed
 * right away or should be queued for processing later.
 */
static bool ima_process_keys;

/*
 * To synchronize access to the list of keys that need to be measured
 */
static DEFINE_MUTEX(ima_keys_lock);
static LIST_HEAD(ima_keys);

/*
 * If custom IMA policy is not loaded then keys queued up
 * for measurement should be freed. This worker is used
 * for handling this scenario.
 */
static long ima_key_queue_timeout = …; /* 5 Minutes */
static void ima_keys_handler(struct work_struct *work);
static DECLARE_DELAYED_WORK(ima_keys_delayed_work, ima_keys_handler);
static bool timer_expired;

/*
 * This worker function frees keys that may still be
 * queued up in case custom IMA policy was not loaded.
 */
static void ima_keys_handler(struct work_struct *work)
{ … }

/*
 * This function sets up a worker to free queued keys in case
 * custom IMA policy was never loaded.
 */
void ima_init_key_queue(void)
{ … }

static void ima_free_key_entry(struct ima_key_entry *entry)
{ … }

static struct ima_key_entry *ima_alloc_key_entry(struct key *keyring,
						 const void *payload,
						 size_t payload_len)
{ … }

bool ima_queue_key(struct key *keyring, const void *payload,
		   size_t payload_len)
{ … }

/*
 * ima_process_queued_keys() - process keys queued for measurement
 *
 * This function sets ima_process_keys to true and processes queued keys.
 * From here on keys will be processed right away (not queued).
 */
void ima_process_queued_keys(void)
{ … }

inline bool ima_should_queue_key(void)
{ … }