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// SPDX-License-Identifier: GPL-2.0+
/*
* Copyright (C) 2019 Microsoft Corporation
*
* Author: Lakshmi Ramasubramanian (nramas@linux.microsoft.com)
*
* 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 = 300000; /* 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)
{
timer_expired = true;
ima_process_queued_keys();
}
/*
* This function sets up a worker to free queued keys in case
* custom IMA policy was never loaded.
*/
void ima_init_key_queue(void)
{
schedule_delayed_work(&ima_keys_delayed_work,
msecs_to_jiffies(ima_key_queue_timeout));
}
static void ima_free_key_entry(struct ima_key_entry *entry)
{
if (entry) {
kfree(entry->payload);
kfree(entry->keyring_name);
kfree(entry);
}
}
static struct ima_key_entry *ima_alloc_key_entry(struct key *keyring,
const void *payload,
size_t payload_len)
{
int rc = 0;
const char *audit_cause = "ENOMEM";
struct ima_key_entry *entry;
entry = kzalloc(sizeof(*entry), GFP_KERNEL);
if (entry) {
entry->payload = kmemdup(payload, payload_len, GFP_KERNEL);
entry->keyring_name = kstrdup(keyring->description,
GFP_KERNEL);
entry->payload_len = payload_len;
}
if ((entry == NULL) || (entry->payload == NULL) ||
(entry->keyring_name == NULL)) {
rc = -ENOMEM;
goto out;
}
INIT_LIST_HEAD(&entry->list);
out:
if (rc) {
integrity_audit_message(AUDIT_INTEGRITY_PCR, NULL,
keyring->description,
func_measure_str(KEY_CHECK),
audit_cause, rc, 0, rc);
ima_free_key_entry(entry);
entry = NULL;
}
return entry;
}
bool ima_queue_key(struct key *keyring, const void *payload,
size_t payload_len)
{
bool queued = false;
struct ima_key_entry *entry;
entry = ima_alloc_key_entry(keyring, payload, payload_len);
if (!entry)
return false;
mutex_lock(&ima_keys_lock);
if (!ima_process_keys) {
list_add_tail(&entry->list, &ima_keys);
queued = true;
}
mutex_unlock(&ima_keys_lock);
if (!queued)
ima_free_key_entry(entry);
return queued;
}
/*
* 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)
{
struct ima_key_entry *entry, *tmp;
bool process = false;
if (ima_process_keys)
return;
/*
* Since ima_process_keys is set to true, any new key will be
* processed immediately and not be queued to ima_keys list.
* First one setting the ima_process_keys flag to true will
* process the queued keys.
*/
mutex_lock(&ima_keys_lock);
if (!ima_process_keys) {
ima_process_keys = true;
process = true;
}
mutex_unlock(&ima_keys_lock);
if (!process)
return;
if (!timer_expired)
cancel_delayed_work_sync(&ima_keys_delayed_work);
list_for_each_entry_safe(entry, tmp, &ima_keys, list) {
if (!timer_expired)
process_buffer_measurement(&nop_mnt_idmap, NULL,
entry->payload,
entry->payload_len,
entry->keyring_name,
KEY_CHECK, 0,
entry->keyring_name,
false, NULL, 0);
list_del(&entry->list);
ima_free_key_entry(entry);
}
}
inline bool ima_should_queue_key(void)
{
return !ima_process_keys;
}
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