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177 lines
4.0 KiB
177 lines
4.0 KiB
// SPDX-License-Identifier: GPL-2.0+ |
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/* |
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* Copyright (C) 2019 Microsoft Corporation |
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* |
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* Author: Lakshmi Ramasubramanian ([email protected]) |
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* |
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* File: ima_queue_keys.c |
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* Enables deferred processing of keys |
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*/ |
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#include <linux/user_namespace.h> |
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#include <linux/workqueue.h> |
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#include <keys/asymmetric-type.h> |
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#include "ima.h" |
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/* |
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* Flag to indicate whether a key can be processed |
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* right away or should be queued for processing later. |
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*/ |
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static bool ima_process_keys; |
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/* |
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* To synchronize access to the list of keys that need to be measured |
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*/ |
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static DEFINE_MUTEX(ima_keys_lock); |
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static LIST_HEAD(ima_keys); |
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/* |
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* If custom IMA policy is not loaded then keys queued up |
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* for measurement should be freed. This worker is used |
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* for handling this scenario. |
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*/ |
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static long ima_key_queue_timeout = 300000; /* 5 Minutes */ |
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static void ima_keys_handler(struct work_struct *work); |
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static DECLARE_DELAYED_WORK(ima_keys_delayed_work, ima_keys_handler); |
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static bool timer_expired; |
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/* |
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* This worker function frees keys that may still be |
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* queued up in case custom IMA policy was not loaded. |
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*/ |
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static void ima_keys_handler(struct work_struct *work) |
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{ |
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timer_expired = true; |
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ima_process_queued_keys(); |
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} |
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/* |
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* This function sets up a worker to free queued keys in case |
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* custom IMA policy was never loaded. |
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*/ |
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void ima_init_key_queue(void) |
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{ |
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schedule_delayed_work(&ima_keys_delayed_work, |
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msecs_to_jiffies(ima_key_queue_timeout)); |
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} |
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static void ima_free_key_entry(struct ima_key_entry *entry) |
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{ |
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if (entry) { |
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kfree(entry->payload); |
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kfree(entry->keyring_name); |
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kfree(entry); |
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} |
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} |
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static struct ima_key_entry *ima_alloc_key_entry(struct key *keyring, |
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const void *payload, |
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size_t payload_len) |
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{ |
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int rc = 0; |
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const char *audit_cause = "ENOMEM"; |
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struct ima_key_entry *entry; |
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entry = kzalloc(sizeof(*entry), GFP_KERNEL); |
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if (entry) { |
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entry->payload = kmemdup(payload, payload_len, GFP_KERNEL); |
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entry->keyring_name = kstrdup(keyring->description, |
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GFP_KERNEL); |
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entry->payload_len = payload_len; |
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} |
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if ((entry == NULL) || (entry->payload == NULL) || |
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(entry->keyring_name == NULL)) { |
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rc = -ENOMEM; |
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goto out; |
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} |
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INIT_LIST_HEAD(&entry->list); |
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out: |
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if (rc) { |
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integrity_audit_message(AUDIT_INTEGRITY_PCR, NULL, |
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keyring->description, |
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func_measure_str(KEY_CHECK), |
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audit_cause, rc, 0, rc); |
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ima_free_key_entry(entry); |
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entry = NULL; |
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} |
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return entry; |
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} |
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bool ima_queue_key(struct key *keyring, const void *payload, |
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size_t payload_len) |
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{ |
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bool queued = false; |
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struct ima_key_entry *entry; |
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entry = ima_alloc_key_entry(keyring, payload, payload_len); |
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if (!entry) |
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return false; |
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mutex_lock(&ima_keys_lock); |
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if (!ima_process_keys) { |
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list_add_tail(&entry->list, &ima_keys); |
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queued = true; |
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} |
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mutex_unlock(&ima_keys_lock); |
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if (!queued) |
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ima_free_key_entry(entry); |
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return queued; |
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} |
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/* |
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* ima_process_queued_keys() - process keys queued for measurement |
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* |
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* This function sets ima_process_keys to true and processes queued keys. |
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* From here on keys will be processed right away (not queued). |
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*/ |
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void ima_process_queued_keys(void) |
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{ |
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struct ima_key_entry *entry, *tmp; |
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bool process = false; |
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if (ima_process_keys) |
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return; |
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/* |
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* Since ima_process_keys is set to true, any new key will be |
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* processed immediately and not be queued to ima_keys list. |
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* First one setting the ima_process_keys flag to true will |
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* process the queued keys. |
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*/ |
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mutex_lock(&ima_keys_lock); |
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if (!ima_process_keys) { |
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ima_process_keys = true; |
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process = true; |
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} |
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mutex_unlock(&ima_keys_lock); |
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if (!process) |
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return; |
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if (!timer_expired) |
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cancel_delayed_work_sync(&ima_keys_delayed_work); |
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list_for_each_entry_safe(entry, tmp, &ima_keys, list) { |
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if (!timer_expired) |
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process_buffer_measurement(&init_user_ns, NULL, |
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entry->payload, |
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entry->payload_len, |
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entry->keyring_name, |
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KEY_CHECK, 0, |
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entry->keyring_name, |
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false); |
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list_del(&entry->list); |
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ima_free_key_entry(entry); |
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} |
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} |
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inline bool ima_should_queue_key(void) |
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{ |
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return !ima_process_keys; |
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}
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