linux-kernel - Re: [PATCH v3 2/3] IMA: Add log statements for failure conditions.

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Date:   Wed, 12 Feb 2020 14:30:26 -0800
From:   Tushar Sugandhi <tusharsu@...ux.microsoft.com>
To:     Mimi Zohar <zohar@...ux.ibm.com>, joe@...ches.com,
        skhan@...uxfoundation.org, linux-integrity@...r.kernel.org
Cc:     sashal@...nel.org, nramas@...ux.microsoft.com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 2/3] IMA: Add log statements for failure conditions.



On 2020-02-12 6:47 a.m., Mimi Zohar wrote:
> Hi Tushar,
> 
> Please remove the period at the end of the  Subject line.
Thanks. I will fix it in the next iteration.
> 
> On Tue, 2020-02-11 at 15:14 -0800, Tushar Sugandhi wrote:
>> process_buffer_measurement() does not have log messages for failure
>> conditions.
>>
>> This change adds a log statement in the above function.
> 
> I agree some form of notification needs to be added.  The question is
> whether the failure should be audited or a kernel message emitted.
>   IMA emits audit messages (integrity_audit_msg) for a number of
> reasons - on failure to calculate a file hash, invalid policy rules,
> failure to communicate with the TPM, signature verification errors,
> etc.
I believe both IMA audit messages and kernel message should be emitted -
for better discoverability and diagnosability.
> 
>>
>> Signed-off-by: Tushar Sugandhi <tusharsu@...ux.microsoft.com>
>> Reviewed-by: Lakshmi Ramasubramanian <nramas@...ux.microsoft.com>
>> Suggested-by: Joe Perches <joe@...ches.com>
>> ---
>>   security/integrity/ima/ima_main.c | 3 +++
>>   1 file changed, 3 insertions(+)
>>
>> diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
>> index 9fe949c6a530..6e1576d9eb48 100644
>> --- a/security/integrity/ima/ima_main.c
>> +++ b/security/integrity/ima/ima_main.c
>> @@ -757,6 +757,9 @@ void process_buffer_measurement(const void *buf, int size,
>>   		ima_free_template_entry(entry);
>>   
>>   out:
>> +	if (ret < 0)
>> +		pr_err("%s: failed, result: %d\n", __func__, ret);
>> +
>>   	return;
>>   }
>>   
> 
> With 3/3 "IMA: Add module name and base name prefix to log", the
> resulting message will be "KBUILD_MODNAME: KBUILD_BASENAME: func:".
>   Isn't that a bit much?
> 
For this specific message, it will look like below.
"ima: ima_main: process_buffer_measurement: failed, result: %d"

In general, adding KBUILD_BASENAME seems helpful to pinpoint the 
location of the issue.


> Mimi
>