On 2/23/21 9:31 AM, Petr Vorel wrote:
ima-buf is the default IMA template used for all buffer measurements.
Therefore, IMA policy rule for measuring keys need not specify
an IMA template.
Good catch. But was it alway?
IMHO ima-buf as default was added in dea87d0889dd ("ima: select ima-buf template for buffer measurement") in v5.11-rc1.
For key measurements ima-buf template was required in the policy rule, but
with the above commit (dea87d0889dd) it was changed to ima-buf. So we no
longer need to specify the template in the policy.
But test1() tests 450d0fd51564 ("IMA: Call workqueue functions to measure queued keys") from v5.6-rc1.
Is it safe to ignore it?
Even when the key is queued for measurement, ima-buf template will be used
when the key is dequeued. Not sure if that answers your question.
IMHO template=ima-buf is required from v5.6-rc1 to v5.10, right?
That is correct Petr.
But maybe it's just enough to check that no other template is used as we discuss
below.
I agree.
BTW template=ima-buf requirement was added in commit b0418c93f ("IMA/ima_keys.sh: Require template=ima-buf, fix grep pattern")
Also, shouldn't we check that there is none of the other templates (e.g. template=ima-ng, ...)?
This is a good point - yes: we should check if no other template other than
ima-buf is specified in the policy rule for measuring keys.
It'd be great if you include it in v2.
Will do.
...
FUNC_KEYCHECK='func=KEY_CHECK'
-TEMPLATE_BUF='template=ima-buf'
-REQUIRED_POLICY="^measure.*($FUNC_KEYCHECK.*$TEMPLATE_BUF|$TEMPLATE_BUF.*$FUNC_KEYCHECK)"
+REQUIRED_POLICY="^measure.*($FUNC_KEYCHECK)"
nit: remove brackets:
REQUIRED_POLICY="^measure.*$FUNC_KEYCHECK"
Sure - will remove that.
Thanks!
There is
testcases/kernel/security/integrity/ima/datafiles/ima_keys/keycheck.policy file,
which should be a helper to load proper policy and needs to be updated as well:
-measure func=KEY_CHECK keyrings=.ima|.evm|.builtin_trusted_keys|.blacklist|key_import_test template=ima-buf
+measure func=KEY_CHECK keyrings=.ima|.evm|.builtin_trusted_keys|.blacklist|key_import_test
I was also thinking to move keyrings to REQUIRED_POLICY, e.g.:
KEYRINGS="keyrings=\.[a-z]+"
REQUIRED_POLICY="^measure.*($FUNC_KEYCHECK.*$KEYRINGS|$KEYRINGS.*$FUNC_KEYCHECK)"
"keyrings=" is optional in the policy. If keyrings is specified it should be
checked.
OK, just optional.
I'll see how to validate an optional field and update the test.
thanks,
-lakshmi
