summaryrefslogtreecommitdiffstats
path: root/security/integrity/ima/ima_queue_keys.c
diff options
context:
space:
mode:
Diffstat (limited to 'security/integrity/ima/ima_queue_keys.c')
-rw-r--r--security/integrity/ima/ima_queue_keys.c177
1 files changed, 177 insertions, 0 deletions
diff --git a/security/integrity/ima/ima_queue_keys.c b/security/integrity/ima/ima_queue_keys.c
new file mode 100644
index 000000000..93056c03b
--- /dev/null
+++ b/security/integrity/ima/ima_queue_keys.c
@@ -0,0 +1,177 @@
+// 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(&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;
+}