Re: [PATCH] IMA: Handle early boot data measurement

From: Lakshmi Ramasubramanian
Date: Tue Aug 25 2020 - 15:35:27 EST


On 8/25/20 11:03 AM, Mimi Zohar wrote:
On Tue, 2020-08-25 at 10:55 -0700, Lakshmi Ramasubramanian wrote:
On 8/25/20 10:42 AM, Mimi Zohar wrote:

Please limit the changes in this patch to renaming the functions and/or
files. For example, adding "measure_payload_hash" should be a separate
patch, not hidden here.


Thanks for the feedback Mimi.

I'll split this into 2 patches:

PATCH 1: Rename files + rename CONFIG
PATCH 2: Update IMA hook to utilize early boot data measurement.

I'm referring to introducing the "measure_payload_hash" flag. I assume
this is to indicate whether the buffer should be hashed or not.

Example 1: ima_alloc_key_entry() and ima_alloc_data_entry(0 comparison
-static struct ima_key_entry *ima_alloc_key_entry(struct key *keyring,
- const void *payload,
- size_t payload_len)
-{
+static struct ima_data_entry *ima_alloc_data_entry(const char *event_name,
+ const void *payload,
+ size_t payload_len,
+ const char *event_data,
+ enum ima_hooks func,
+ bool measure_payload_hash) <====
+{

Example 2:
diff --git a/security/integrity/ima/ima_asymmetric_keys.c b/security/integrity/ima/ima_asymmetric_keys.c
index a74095793936..65423754765f 100644
--- a/security/integrity/ima/ima_asymmetric_keys.c
+++ b/security/integrity/ima/ima_asymmetric_keys.c
@@ -37,9 +37,10 @@ void ima_post_key_create_or_update(struct key *keyring, struct key *key,
if (!payload || (payload_len == 0))
return;
- if (ima_should_queue_key())
- queued = ima_queue_key(keyring, payload, payload_len);
-
+ if (ima_should_queue_data())
+ queued = ima_queue_data(keyring->description, payload,
+ payload_len, keyring->description,
+ KEY_CHECK, false); <===
if (queued)
return;

But in general, as much as possible function and file name changes
should be done independently of other changes.

thanks,

I agree - but in this case, Tushar's patch series on adding support for
"Critical Data" measurement has already introduced
"measure_payload_hash" flag. His patch updates
"process_buffer_measurement()" to take this new flag and measure hash of
the given data.

My patches extend that to queuing the early boot requests and processing
them after a custom IMA policy is loaded.

If you still think "measure_payload_hash" flag should be introduced in
the queuing change as a separate patch I'll split the patches further.
Please let me know.

There's a major problem if his changes add new function arguments
without modifying all the callers of the function. I assume the kernel
would fail to compile properly.

Tushar's patch series does update all the existing callers of process_buffer_measurement() to handle the new arguments. His patch series is self contained, and builds and works fine.


Changing the function parameters to include "measure_payload_hash"
needs to be a separate patch, whether it is part of his patch set or
yours.


ok - I'll split the queuing patch to include "measure_payload_hash" in a separate patch.

thanks,
-lakshmi