Re: [PATCH] IMA: Add test for selinux measurement

[Lakshmi Ramasubramanian <nramas@linux.microsoft.com>]

On 2/23/21 2:14 PM, Petr Vorel wrote:
>> On 2/23/21 10:00 AM, Petr Vorel wrote:
> 
> 
>>>> +++ b/testcases/kernel/security/integrity/ima/tests/ima_selinux.sh
>>> ...
>>>> +validate_policy_capabilities()
>>>> +{
>>>> +	local measured_cap measured_value expected_value
>>>> +	local result=1
>>>> +	local inx=7
>>>> +
>>>> +	# Policy capabilities flags start from "network_peer_controls"
>>>> +	# in the measured SELinux state at offset 7 for 'awk'
>>>> +	while [ $inx -lt 20 ]; do
>>>> +		measured_cap=$(echo $1 | awk -F'[=;]' -v inx="$inx" '{print $inx}')
>>>> +		inx=$(( $inx + 1 ))
>>>> +
>>>> +		measured_value=$(echo $1 | awk -F'[=;]' -v inx="$inx" '{print $inx}')
>>>> +		expected_value=$(cat "$SELINUX_DIR/policy_capabilities/$measured_cap")
>>>> +		if [ "$measured_value" != "$expected_value" ];then
>>>> +			tst_res TWARN "$measured_cap: expected: $expected_value, got: $digest"
>>> We rarely use TWARN in the tests, only when the error is not related to the test result.
>>> Otherwise we use TFAIL.
>> ok - I will change it to TFAIL.
> Thanks!
> But I've noticed that this error is handled twice, first in validate_policy_capabilities()
> as TWARN (or TFAIL) and then in test2(). Let's use TPASS/TFAIL in
> validate_policy_capabilities():
Sure - will make that change.

> 
> validate_policy_capabilities()
> {
> 	local measured_cap measured_value expected_value
> 	local inx=7
> 
> 	# Policy capabilities flags start from "network_peer_controls"
> 	# in the measured SELinux state at offset 7 for 'awk'
> 	while [ $inx -lt 20 ]; do
> 		measured_cap=$(echo $1 | awk -F'[=;]' -v inx="$inx" '{print $inx}')
> 		inx=$(($inx + 1))
> 
> 		measured_value=$(echo $1 | awk -F'[=;]' -v inx="$inx" '{print $inx}')
> 		expected_value=$(cat "$SELINUX_DIR/policy_capabilities/$measured_cap")
> 		if [ "$measured_value" != "$expected_value" ]; then
> 			tst_res TFAIL "$measured_cap: expected: $expected_value, got: $digest"
> 			return
> 		fi
> 
> 		inx=$(($inx + 1))
> 	done
> 
> 	tst_res TPASS "SELinux state measured correctly"
> }
> 
> test2()
> {
> 	...
> 	validate_policy_capabilities $measured_data
> }
> 
> ...
>>> As we discuss, I'm going tom merge test when patchset is merged in maintainers tree,
>>> please ping me. And ideally we should mention kernel commit hash as a comment in
>>> the test.
>> Will do. Thank you.
> Thanks!
> 
> ...
>>> +++ testcases/kernel/security/integrity/ima/tests/ima_selinux.sh
>>> @@ -13,16 +13,14 @@ TST_SETUP="setup"
>>>    . ima_setup.sh
>>>    FUNC_CRITICAL_DATA='func=CRITICAL_DATA'
>>> -REQUIRED_POLICY="^measure.*($FUNC_CRITICAL_DATA)"
>>> +REQUIRED_POLICY="^measure.*$FUNC_CRITICAL_DATA"
>>>    setup()
>>>    {
>>> -	SELINUX_DIR=$(tst_get_selinux_dir)
>>> -	if [ -z "$SELINUX_DIR" ]; then
>>> -		tst_brk TCONF "SELinux is not enabled"
>>> -		return
>>> -	fi
>>> +	tst_require_selinux_enabled
>> Please correct me if I have misunderstood this one:
> 
>> tst_require_selinux_enabled is checking if SELinux is enabled in "enforce"
>> mode. Would this check fail if SELinux is enabled in "permissive" mode?
> 
>> For running the test, we just need SELinux to be enabled. I verify that by
>> checking for the presence of SELINUX_DIR.
> 
> Good catch. Your original version is correct (put it back into ima/selinux.v2.fixes).
> I didn't put a helper for it, because you need $SELINUX_DIR anyway.
> Thus removed tst_require_selinux_enabled() as not needed.
Thanks

> 
> I renamed tst_selinux_enabled() to tst_selinux_enforced() to make the purpose clearer
> (commit 82b598ea1 IMA: Add test for selinux measurement).
> 
> I've updated branch ima/selinux.v2.fixes with all mentioned changes
> https://github.com/pevik/ltp/commits/ima/selinux.v2.fixes
> 
Thanks again. I'll make my changes in this branch and post the patches 
later this week.

  -lakshmi