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 <[email protected]>
---
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 ([email protected])
+ *
+ * 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
Hi Lakshmi,
On Wed, 2020-01-22 at 17:32 -0800, Lakshmi Ramasubramanian wrote:
> 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.
The addition of "and the keys" makes the sentence a run-on. I've
reverted this change.
>
> 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 <[email protected]>
Thanks! With this patch, if queueing keys ever becomes an issue,
resolving it will be straight forward.
This patch set is now in the next-integrity-testing branch. Assuming
there are no problems, it will be merged into the next-integrity
branch, requiring a rebase. I'm sorry for any inconvenience this may
cause.
Mimi
> ---
> 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 ([email protected])
> + *
> + * 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;
> +}