Measuring keys requires a custom IMA policy to be loaded.
Keys created or updated before a custom IMA policy is loaded should
be queued and the keys should be processed after a custom policy
is loaded.
This patch defines workqueue for queuing keys when a custom IMA policy
has not yet been loaded. An intermediate Kconfig boolean option namely
IMA_QUEUE_EARLY_BOOT_KEYS is used to declare the workqueue functions.
A flag namely ima_process_keys is used to check if the key should be
queued or should be processed immediately.
Signed-off-by: Lakshmi Ramasubramanian <nramas@xxxxxxxxxxxxxxxxxxx>
---
security/integrity/ima/Kconfig | 5 +
security/integrity/ima/Makefile | 1 +
security/integrity/ima/ima.h | 22 ++++
security/integrity/ima/ima_queue_keys.c | 137 ++++++++++++++++++++++++
4 files changed, 165 insertions(+)
create mode 100644 security/integrity/ima/ima_queue_keys.c
diff --git a/security/integrity/ima/Kconfig b/security/integrity/ima/Kconfig
index 6bec78eeeae8..711ff10fa36e 100644
--- a/security/integrity/ima/Kconfig
+++ b/security/integrity/ima/Kconfig
@@ -317,3 +317,8 @@ config IMA_MEASURE_ASYMMETRIC_KEYS
depends on ASYMMETRIC_PUBLIC_KEY_SUBTYPE=y
default y
+config IMA_QUEUE_EARLY_BOOT_KEYS
+ bool
+ depends on IMA_MEASURE_ASYMMETRIC_KEYS
+ depends on SYSTEM_TRUSTED_KEYRING
+ default y
diff --git a/security/integrity/ima/Makefile b/security/integrity/ima/Makefile
index 3e9d0ad68c7b..064a256f8725 100644
--- a/security/integrity/ima/Makefile
+++ b/security/integrity/ima/Makefile
@@ -13,3 +13,4 @@ ima-$(CONFIG_IMA_APPRAISE_MODSIG) += ima_modsig.o
ima-$(CONFIG_HAVE_IMA_KEXEC) += ima_kexec.o
obj-$(CONFIG_IMA_BLACKLIST_KEYRING) += ima_mok.o
obj-$(CONFIG_IMA_MEASURE_ASYMMETRIC_KEYS) += ima_asymmetric_keys.o
+obj-$(CONFIG_IMA_QUEUE_EARLY_BOOT_KEYS) += ima_queue_keys.o
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index f06238e41a7c..905ed2f7f778 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -205,6 +205,28 @@ extern const char *const func_tokens[];
struct modsig;
+#ifdef CONFIG_IMA_QUEUE_EARLY_BOOT_KEYS
+/*
+ * To track keys that need to be measured.
+ */
+struct ima_key_entry {
+ struct list_head list;
+ void *payload;
+ size_t payload_len;
+ char *keyring_name;
+};
+bool ima_should_queue_key(void);
+bool ima_queue_key(struct key *keyring, const void *payload,
+ size_t payload_len);
+void ima_process_queued_keys(void);
+#else
+static inline bool ima_should_queue_key(void) { return false; }
+static inline bool ima_queue_key(struct key *keyring,
+ const void *payload,
+ size_t payload_len) { return false; }
+static inline void ima_process_queued_keys(void) {}
+#endif /* CONFIG_IMA_QUEUE_EARLY_BOOT_KEYS */
+
/* LIM API function definitions */
int ima_get_action(struct inode *inode, const struct cred *cred, u32 secid,
int mask, enum ima_hooks func, int *pcr,
diff --git a/security/integrity/ima/ima_queue_keys.c b/security/integrity/ima/ima_queue_keys.c
new file mode 100644
index 000000000000..9b561f2b86db
--- /dev/null
+++ b/security/integrity/ima/ima_queue_keys.c
@@ -0,0 +1,137 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2019 Microsoft Corporation
+ *
+ * Author: Lakshmi Ramasubramanian (nramas@xxxxxxxxxxxxxxxxxxx)
+ *
+ * File: ima_queue_keys.c
+ * Enables deferred processing of keys
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#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);
+
+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;
+
+
+ list_for_each_entry_safe(entry, tmp, &ima_keys, list) {
+ 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;
+}
--
2.17.1
