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authorLinus Torvalds <torvalds@linux-foundation.org>2020-01-28 18:52:09 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2020-01-28 18:52:09 -0800
commit73a0bff2058f2403c604371c325fec737ac2ac61 (patch)
treeb862ab7ec0b6bf155cc491ec34343ac1df25bfa9 /security/integrity/ima/ima_queue_keys.c
parent2cf64d7cb20b04cf25e4ebffc37833298f1d4bde (diff)
parentd54e17b4066612d88c4ef3e5fb3115f12733763d (diff)
Merge branch 'next-integrity' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity
Pull IMA updates from Mimi Zohar: "Two new features - measuring certificates and querying IMA for a file hash - and three bug fixes: - Measuring certificates is like the rest of IMA, based on policy, but requires loading a custom policy. Certificates loaded onto a keyring, for example during early boot, before a custom policy has been loaded, are queued and only processed after loading the custom policy. - IMA calculates and caches files hashes. Other kernel subsystems, and possibly kernel modules, are interested in accessing these cached file hashes. The bug fixes prevent classifying a file short read (e.g. shutdown) as an invalid file signature, add a missing blank when displaying the securityfs policy rules containing LSM labels, and, lastly, fix the handling of the IMA policy information for unknown LSM labels" * 'next-integrity' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity: IMA: Defined delayed workqueue to free the queued keys IMA: Call workqueue functions to measure queued keys IMA: Define workqueue for early boot key measurements IMA: pre-allocate buffer to hold keyrings string ima: ima/lsm policy rule loading logic bug fixes ima: add the ability to query the cached hash of a given file ima: Add a space after printing LSM rules for readability IMA: fix measuring asymmetric keys Kconfig IMA: Read keyrings= option from the IMA policy IMA: Add support to limit measuring keys KEYS: Call the IMA hook to measure keys IMA: Define an IMA hook to measure keys IMA: Add KEY_CHECK func to measure keys IMA: Check IMA policy flag ima: avoid appraise error for hash calc interrupt
Diffstat (limited to 'security/integrity/ima/ima_queue_keys.c')
-rw-r--r--security/integrity/ima/ima_queue_keys.c171
1 files changed, 171 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 000000000000..c87c72299191
--- /dev/null
+++ b/security/integrity/ima/ima_queue_keys.c
@@ -0,0 +1,171 @@
+// 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
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#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;
+}