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Date: Thu, 23 Jan 2020 09:19:58 -0500
From: Mimi Zohar <zohar@...ux.ibm.com>
To: Lakshmi Ramasubramanian <nramas@...ux.microsoft.com>,
James.Bottomley@...senPartnership.com,
linux-integrity@...r.kernel.org
Cc: sashal@...nel.org, dhowells@...hat.com,
linux-kernel@...r.kernel.org, keyrings@...r.kernel.org
Subject: Re: [PATCH v9 1/3] IMA: Define workqueue for early boot key
measurements
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 <nramas@...ux.microsoft.com>
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 (nramas@...ux.microsoft.com)
> + *
> + * 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;
> +}
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