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;
+}