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- // 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 = 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(&init_user_ns, 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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