linux-kernel - Re: [RFC][PATCH 3/4] ima: display template format in meas. list if template name length is zero

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Message-ID: <52A03EF0.4080702@polito.it>
Date:	Thu, 05 Dec 2013 09:53:04 +0100
From:	Roberto Sassu <roberto.sassu@...ito.it>
To:	Mimi Zohar <zohar@...ux.vnet.ibm.com>
CC:	linux-security-module@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-ima-devel@...ts.sourceforge.net, zohar@...ibm.com,
	d.kasatkin@...sung.com, james.l.morris@...cle.com
Subject: Re: [RFC][PATCH 3/4] ima: display template format in meas. list if
 template name length is zero

On 12/04/2013 10:08 PM, Mimi Zohar wrote:
> On Thu, 2013-11-07 at 15:00 +0100, Roberto Sassu wrote:
>> With the introduction of the 'ima_template_fmt' kernel cmdline parameter,
>> an user can define a new template descriptor with custom format. However,
>> in this case, userspace tools will be unable to parse the measurements
>> list because the new template is unknown. For this reason, this patch
>> modifies the current IMA behavior to display in the list the template
>> format instead of the name so that a tool can extract needed information
>> if it can handle listed fields.
>>
>> Signed-off-by: Roberto Sassu <roberto.sassu@...ito.it>
>> ---
>>   security/integrity/ima/ima_fs.c | 18 ++++++++++++++----
>>   1 file changed, 14 insertions(+), 4 deletions(-)
>>
>> diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_fs.c
>> index d47a7c8..6db74ff 100644
>> --- a/security/integrity/ima/ima_fs.c
>> +++ b/security/integrity/ima/ima_fs.c
>> @@ -118,6 +118,7 @@ static int ima_measurements_show(struct seq_file *m, void *v)
>>   	/* the list never shrinks, so we don't need a lock here */
>>   	struct ima_queue_entry *qe = v;
>>   	struct ima_template_entry *e;
>> +	char *template_name;
>>   	int namelen;
>>   	u32 pcr = CONFIG_IMA_MEASURE_PCR_IDX;
>>   	int i;
>> @@ -127,6 +128,10 @@ static int ima_measurements_show(struct seq_file *m, void *v)
>>   	if (e == NULL)
>>   		return -1;
>>
>> +	template_name = e->template_desc->name;
>> +	if (strlen(e->template_desc->name) == 0)
>> +		template_name = e->template_desc->fmt;
>> +
>
> Hi Roberto,
>
> The patch description unconditionally says, "this patch modifies the
> current IMA behavior to display in the list the template format instead
> of the name".  The code only uses the 'fmt', if the name doesn't exist.
> Please update the patch description accordingly.
>
> Nothing is wrong with the above syntax, but template_name could be
> assigned once using a ternary conditional expression(?:), like:
>
> 	template_name = (strlen(e->template_desc->name) == 0) ?
> 		e->template_desc->name : e->template_desc->fmt;
>

Ok, I will make the changes.

Thanks

Roberto Sassu


> thanks,
>
> Mimi
>
>>   	/*
>>   	 * 1st: PCRIndex
>>   	 * PCR used is always the same (config option) in
>> @@ -138,14 +143,14 @@ static int ima_measurements_show(struct seq_file *m, void *v)
>>   	ima_putc(m, e->digest, TPM_DIGEST_SIZE);
>>
>>   	/* 3rd: template name size */
>> -	namelen = strlen(e->template_desc->name);
>> +	namelen = strlen(template_name);
>>   	ima_putc(m, &namelen, sizeof namelen);
>>
>>   	/* 4th:  template name */
>> -	ima_putc(m, e->template_desc->name, namelen);
>> +	ima_putc(m, template_name, namelen);
>>
>>   	/* 5th:  template length (except for 'ima' template) */
>> -	if (strcmp(e->template_desc->name, IMA_TEMPLATE_IMA_NAME) != 0)
>> +	if (strcmp(template_name, IMA_TEMPLATE_IMA_NAME) != 0)
>>   		ima_putc(m, &e->template_data_len,
>>   			 sizeof(e->template_data_len));
>>
>> @@ -190,6 +195,7 @@ static int ima_ascii_measurements_show(struct seq_file *m, void *v)
>>   	/* the list never shrinks, so we don't need a lock here */
>>   	struct ima_queue_entry *qe = v;
>>   	struct ima_template_entry *e;
>> +	char *template_name;
>>   	int i;
>>
>>   	/* get entry */
>> @@ -197,6 +203,10 @@ static int ima_ascii_measurements_show(struct seq_file *m, void *v)
>>   	if (e == NULL)
>>   		return -1;
>>
>> +	template_name = e->template_desc->name;
>> +	if (strlen(e->template_desc->name) == 0)
>> +		template_name = e->template_desc->fmt;
>> +
>>   	/* 1st: PCR used (config option) */
>>   	seq_printf(m, "%2d ", CONFIG_IMA_MEASURE_PCR_IDX);
>>
>> @@ -204,7 +214,7 @@ static int ima_ascii_measurements_show(struct seq_file *m, void *v)
>>   	ima_print_digest(m, e->digest, TPM_DIGEST_SIZE);
>>
>>   	/* 3th:  template name */
>> -	seq_printf(m, " %s", e->template_desc->name);
>> +	seq_printf(m, " %s", template_name);
>>
>>   	/* 4th:  template specific data */
>>   	for (i = 0; i < e->template_desc->num_fields; i++) {
>
>

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