Re: [PATCH v4 08/10] IMA: Defined functions to queue and dequeue keys for measurement

Mimi Zohar
2019-11-06T22:44:54Z

On Wed, 2019-11-06 at 11:01 -0800, Lakshmi Ramasubramanian wrote:

> +int ima_queue_or_process_key_for_measurement(struct key *keyring,
> + struct key *key)
> +{
> + int rc = 0;
> + struct ima_measure_key_entry *entry = NULL;
> + const struct public_key *pk;
> +
> + if (key->type != &key_type_asymmetric)
> + return 0;
> +
> + mutex_lock(&ima_measure_keys_mutex);

Unless the key is being queued, there's no reason to take the lock.

> +
> + if (ima_initialized) {

ima_initialized is being set in ima_init(), before a custom policy is
loaded.  I would think that is too early.  ima_update_policy() is
called after loading a custom policy.  Please see how to detect when a
custom policy is loaded.

> + /*
> + * keyring->description points to the name of the keyring
> + * (such as ".builtin_trusted_keys", ".ima", etc.) to
> + * which the given key is linked to.
> + *
> + * The name of the keyring is passed in the "eventname"
> + * parameter to process_buffer_measurement() and is set
> + * in the "eventname" field in ima_event_data for
> + * the key measurement IMA event.
> + *
> + * The name of the keyring is also passed in the "keyring"
> + * parameter to process_buffer_measurement() to check
> + * if the IMA policy is configured to measure a key linked
> + * to the given keyring.
> + */
> + pk = key->payload.data[asym_crypto];
> + process_buffer_measurement(pk->key, pk->keylen,
> + keyring->description,
> + KEYRING_CHECK, 0,
> + keyring->description);

Measuring the key should be done in ima_post_key_create_or_update()
unless, it is being deferred.  Please update the function name to
reflect this.

Mimi

> + } else {
> + entry = ima_alloc_measure_key_entry(keyring, key);
> + if (entry != NULL) {
> + INIT_LIST_HEAD(&entry->list);
> + list_add_tail(&entry->list, &ima_measure_keys);
> + } else
> + rc = -ENOMEM;
> + }
> +
> + mutex_unlock(&ima_measure_keys_mutex);
> +
> + return rc;
> +}