Re: [PATCH v9 1/8] IMA: generalize keyring specific measurement constructs

[Tushar Sugandhi <tusharsu@linux.microsoft.com>]

Hello Mimi,
Sorry for the late response. I was on vacation last week.

On 2020-12-24 5:06 a.m., Mimi Zohar wrote:
> On Sat, 2020-12-12 at 10:02 -0800, Tushar Sugandhi wrote:
>>
>> diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
>> index 68956e884403..e76ef4bfd0f4 100644
>> --- a/security/integrity/ima/ima_main.c
>> +++ b/security/integrity/ima/ima_main.c
>> @@ -786,13 +786,13 @@ int ima_post_load_data(char *buf, loff_t size,
>>    * @eventname: event name to be used for the buffer entry.
>>    * @func: IMA hook
>>    * @pcr: pcr to extend the measurement
>> - * @keyring: keyring name to determine the action to be performed
>> + * @func_data: private data specific to @func, can be NULL.
> 
> This can be simplified to "func specific data, may be NULL".   Please
> update in all places.
> 
Ok, will do.
>>    *
>>    * Based on policy, the buffer is measured into the ima log.
>>    */
>>   void process_buffer_measurement(struct inode *inode, const void *buf, int size,
>>   				const char *eventname, enum ima_hooks func,
>> -				int pcr, const char *keyring)
>> +				int pcr, const char *func_data)
>>   {
>>   	int ret = 0;
>>   	const char *audit_cause = "ENOMEM";
>> @@ -831,7 +831,7 @@ void process_buffer_measurement(struct inode *inode, const void *buf, int size,
>>   	if (func) {
>>   		security_task_getsecid(current, &secid);
>>   		action = ima_get_action(inode, current_cred(), secid, 0, func,
>> -					&pcr, &template, keyring);
>> +					&pcr, &template, func_data);
>>   		if (!(action & IMA_MEASURE))
>>   			return;
>>   	}
>> diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
>> index 823a0c1379cb..a09d1a41a290 100644
>> --- a/security/integrity/ima/ima_policy.c
>> +++ b/security/integrity/ima/ima_policy.c
>> @@ -453,30 +453,41 @@ int ima_lsm_policy_change(struct notifier_block *nb, unsigned long event,
>>   }
>>   
>>   /**
>> - * ima_match_keyring - determine whether the keyring matches the measure rule
>> - * @rule: a pointer to a rule
>> - * @keyring: name of the keyring to match against the measure rule
>> + * ima_match_rule_data - determine whether the given func_data matches
>> + *			 the measure rule data
> 
> After the function_name is a brief description of the function, which
> should not span multiple lines.  Refer to Documentation/doc-
> guide/kernel-doc.rst for details.
> 
> Please trim the function description to:
> determine whether func_data matches the policy rule
> 
Thanks, will do.

>> + * @rule: IMA policy rule
> 
> This patch should be limited to renaming "keyring" to "func_data".   It
> shouldn't make other changes, even simple ones like this.
> 
Agreed. I will revert the rule description to the old one.
>> + * @func_data: data to match against the measure rule data
>>    * @cred: a pointer to a credentials structure for user validation
>>    *
>> - * Returns true if keyring matches one in the rule, false otherwise.
>> + * Returns true if func_data matches one in the rule, false otherwise.
>>    */
>> -static bool ima_match_keyring(struct ima_rule_entry *rule,
>> -			      const char *keyring, const struct cred *cred)
>> +static bool ima_match_rule_data(struct ima_rule_entry *rule,
>> +				const char *func_data,
>> +				const struct cred *cred)
>>   {
>> +	const struct ima_rule_opt_list *opt_list = NULL;
>>   	bool matched = false;
>>   	size_t i;
>>   
>>   	if ((rule->flags & IMA_UID) && !rule->uid_op(cred->uid, rule->uid))
>>   		return false;
>>   
>> -	if (!rule->keyrings)
>> -		return true;
>> +	switch (rule->func) {
>> +	case KEY_CHECK:
>> +		if (!rule->keyrings)
>> +			return true;
>> +
>> +		opt_list = rule->keyrings;
>> +		break;
>> +	default:
>> +		return false;
>> +	}
>>   
>> -	if (!keyring)
>> +	if (!func_data)
>>   		return false;
>>   
>> -	for (i = 0; i < rule->keyrings->count; i++) {
>> -		if (!strcmp(rule->keyrings->items[i], keyring)) {
>> +	for (i = 0; i < opt_list->count; i++) {
>> +		if (!strcmp(opt_list->items[i], func_data)) {
>>   			matched = true;
>>   			break;
>>   		}
>> @@ -493,20 +504,20 @@ static bool ima_match_keyring(struct ima_rule_entry *rule,
>>    * @secid: the secid of the task to be validated
>>    * @func: LIM hook identifier
>>    * @mask: requested action (MAY_READ | MAY_WRITE | MAY_APPEND | MAY_EXEC)
>> - * @keyring: keyring name to check in policy for KEY_CHECK func
>> + * @func_data: private data specific to @func, can be NULL.
> 
> Update as previously suggested.
> 
Yes.
>>    *
>>    * Returns true on rule match, false on failure.
>>    */
>>   static bool ima_match_rules(struct ima_rule_entry *rule, struct inode *inode,
>>   			    const struct cred *cred, u32 secid,
>>   			    enum ima_hooks func, int mask,
>> -			    const char *keyring)
>> +			    const char *func_data)
>>   {
>>   	int i;
>>   
>>   	if (func == KEY_CHECK) {
>>   		return (rule->flags & IMA_FUNC) && (rule->func == func) &&
>> -		       ima_match_keyring(rule, keyring, cred);
>> +			ima_match_rule_data(rule, func_data, cred);
>>   	}
>>   	if ((rule->flags & IMA_FUNC) &&
>>   	    (rule->func != func && func != POST_SETATTR))
>> @@ -610,8 +621,7 @@ static int get_subaction(struct ima_rule_entry *rule, enum ima_hooks func)
>>    * @mask: requested action (MAY_READ | MAY_WRITE | MAY_APPEND | MAY_EXEC)
>>    * @pcr: set the pcr to extend
>>    * @template_desc: the template that should be used for this rule
>> - * @keyring: the keyring name, if given, to be used to check in the policy.
>> - *           keyring can be NULL if func is anything other than KEY_CHECK.
>> + * @func_data: private data specific to @func, can be NULL.
> 
> And again here.
> 
Yes.
> thanks,
> 
> Mimi
> 

Thanks,
Tushar