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

[Mimi Zohar]

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.

>   *
>   * 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

> + * @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.

> + * @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.

>   *
>   * 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.

thanks,

Mimi