On 12/2/19 10:00 AM, Mimi Zohar wrote:
ima_update_policy() is called from multiple places. Initially, it is
called before a custom policy has been loaded. The call to
ima_process_queued_keys_for_measurement() needs to be moved to within
the test, otherwise it runs the risk of dropping "key" measurements.
static const struct file_operations ima_measure_policy_ops = {
.release = ima_release_policy,
};
ima_update_policy() is called from ima_release_policy() function.
On my test machine I have the IMA policy in /etc/ima/ima-policy file.
When IMA policy is setup from this file, I see ima_release_policy()
called (which in turn calls ima_update_policy()).
How can I have ima_update_policy() called before a custom policy is loaded?
If CONFIG_IMA_WRITE_POLICY is enabled, IMA policy can be updated at
runtime - which would invoke ima_update_policy().
Is there any other way ima_update_policy() can get called?
All the queued keys need to be processed at the same time. Afterwards
the queue should be deleted. Unfortunately, the current queue locking
assumes ima_process_queued_keys_for_measurement() is called multiple
times.
When ima_process_queued_keys_for_measurement() is called the first time,
the flag ima_process_keys_for_measurement is set to true and all queued
keys are processed at that time.
The queue is not used after this point - In the IMA hook the key is
processed immediately when ima_process_keys_for_measurement is set to true.
ima_process_queued_keys_for_measurement() can be called multiple times,
but on 2nd and subsequent calls it will be a NOP.
Perhaps using the RCU method of walking lists would help. I need to
think about it some more.
Mimi
Please let me know how using RCU method would help.
thanks,
-lakshmi
