| // 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/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; |
| 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) { |
| 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(entry->payload, |
| entry->payload_len, |
| entry->keyring_name, |
| KEY_CHECK, 0, |
| entry->keyring_name); |
| list_del(&entry->list); |
| ima_free_key_entry(entry); |
| } |
| } |
| |
| inline bool ima_should_queue_key(void) |
| { |
| return !ima_process_keys; |
| } |