linux-kernel - Re: [PATCH v9 16/23] ima: Implement ima_free_policy_rules() for freeing of an ima

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Message-ID: <83d32ac3-6633-3ccc-1377-91caaf709445@linux.ibm.com>
Date:   Mon, 31 Jan 2022 13:56:48 -0500
From:   Stefan Berger <stefanb@...ux.ibm.com>
To:     Mimi Zohar <zohar@...ux.ibm.com>,
        Stefan Berger <stefanb@...ux.vnet.ibm.com>,
        linux-integrity@...r.kernel.org
Cc:     serge@...lyn.com, christian.brauner@...ntu.com,
        containers@...ts.linux.dev, dmitry.kasatkin@...il.com,
        ebiederm@...ssion.com, krzysztof.struczynski@...wei.com,
        roberto.sassu@...wei.com, mpeters@...hat.com, lhinds@...hat.com,
        lsturman@...hat.com, puiterwi@...hat.com, jejb@...ux.ibm.com,
        jamjoom@...ibm.com, linux-kernel@...r.kernel.org,
        paul@...l-moore.com, rgb@...hat.com,
        linux-security-module@...r.kernel.org, jmorris@...ei.org
Subject: Re: [PATCH v9 16/23] ima: Implement ima_free_policy_rules() for
 freeing of an ima_namespace


On 1/28/22 09:02, Mimi Zohar wrote:
> Hi Stefan,
>
> On Tue, 2022-01-25 at 17:46 -0500, Stefan Berger wrote:
>> From: Stefan Berger <stefanb@...ux.ibm.com>
>>
>> Implement ima_free_policy_rules() that is needed when an ima_namespace
>> is freed.
>>
>> Only reset temp_ima_appraise when using init_ima_ns.
> Instead of having to walk the policy rules to know if there are any
> "appraise" rules, the ima_appraise flag is set.  For now, only reset
> temp_ima_appraise flag on failed policy rule updates for init_ima_ns.


Ok, I am taking this whole text.


>
>> Signed-off-by: Stefan Berger <stefanb@...ux.ibm.com>
>>
>> ---
>>   v9:
>>    - Only reset temp_ima_appraise when using init_ima_ns.
>> ---
>>   security/integrity/ima/ima.h        |  1 +
>>   security/integrity/ima/ima_policy.c | 20 +++++++++++++++++++-
>>   2 files changed, 20 insertions(+), 1 deletion(-)
>>
>> diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
>> index aea8fb8d2854..8c757223d549 100644
>> --- a/security/integrity/ima/ima.h
>> +++ b/security/integrity/ima/ima.h
>> @@ -329,6 +329,7 @@ void ima_update_policy_flags(struct ima_namespace *ns);
>>   ssize_t ima_parse_add_rule(struct ima_namespace *ns, char *rule);
>>   void ima_delete_rules(struct ima_namespace *ns);
>>   int ima_check_policy(struct ima_namespace *ns);
>> +void ima_free_policy_rules(struct ima_namespace *ns);
>>   void *ima_policy_start(struct seq_file *m, loff_t *pos);
>>   void *ima_policy_next(struct seq_file *m, void *v, loff_t *pos);
>>   void ima_policy_stop(struct seq_file *m, void *v);
>> diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
>> index e8140e73d80b..47f2d1b5d156 100644
>> --- a/security/integrity/ima/ima_policy.c
>> +++ b/security/integrity/ima/ima_policy.c
>> @@ -1880,13 +1880,31 @@ void ima_delete_rules(struct ima_namespace *ns)
>>   {
>>   	struct ima_rule_entry *entry, *tmp;
>>   
>> -	temp_ima_appraise = 0;
>> +	if (ns == &init_ima_ns)
>> +		temp_ima_appraise = 0;
>> +
>>   	list_for_each_entry_safe(entry, tmp, &ns->ima_temp_rules, list) {
>>   		list_del(&entry->list);
>>   		ima_free_rule(entry);
>>   	}
>>   }
>>   
>> +/**
>> + * ima_free_policy_rules - free all policy rules
>> + * @ns: IMA namespace that has the policy
>> + */
>> +void ima_free_policy_rules(struct ima_namespace *ns)
>> +{
>> +	struct ima_rule_entry *entry, *tmp;
>> +
>> +	ima_delete_rules(ns);
> When the IMA policy is being extended, new rules are temporarily added
> to the ima_temp_rules list.  If the entire set of rules being added are
> valid, they're appended to the tail.
>
> There shouldn't be any rules on the ima_temp_rules list unless the
> policy is currently being extended.  Is that possible at this point?

Actually, no. Nothing can be left. I am removing this call.

I wonder whether to split this patch into into two patches?


>
>> +
>> +	list_for_each_entry_safe(entry, tmp, &ns->ima_policy_rules, list) {
>> +		list_del(&entry->list);
>> +		ima_free_rule(entry);
>> +	}
>> +}
>> +
>>   #define __ima_hook_stringify(func, str)	(#func),
>>   
>>   const char *const func_tokens[] = {
> thanks,
>
> Mimi
>