Re: [PATCH v10 16/27] ima: Implement ima_free_policy_rules() for freeing of an ima_namespace

Stefan Berger
2022-02-18T19:38:49Z

On 2/18/22 12:09, Mimi Zohar wrote:
> On Tue, 2022-02-01 at 15:37 -0500, Stefan Berger wrote:
>> Implement ima_free_policy_rules() that is needed when an ima_namespace
>> is freed.
>>
>> Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
>>
>> ---
>> v10:
>> - Not calling ima_delete_rules() anymore
>> - Move access check from ima_delete_rules into very last patch
>>
>> v9:
>> - Only reset temp_ima_appraise when using init_ima_ns.
>> ---
>> security/integrity/ima/ima.h | 1 +
>> security/integrity/ima/ima_policy.c | 14 ++++++++++++++
>> 2 files changed, 15 insertions(+)
>>
>> 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 2dcc5a8c585a..fe3dce8fb939 100644
>> --- a/security/integrity/ima/ima_policy.c
>> +++ b/security/integrity/ima/ima_policy.c
>> @@ -1889,6 +1889,20 @@ void ima_delete_rules(struct ima_namespace *ns)
>> }
>> }
>>
>> +/**
>> + * 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;
>> +
>> + list_for_each_entry_safe(entry, tmp, &ns->ima_policy_rules, list) {
>> + list_del(&entry->list);
>> + ima_free_rule(entry);
>> + }
>> +}
>> +
> The first time a policy is loaded, the policy rules pivot
> from ima_default_rules to the custom rules. When this happens, the
> architecture specific policy rules are freed. Here too, if a custom
> policy isn't already loaded, the architecture specific rules stored as
> an array need to be freed. Refer to the comment in
> ima_update_policy().

Right. So here's how it's done (before arch_policy_entry was moved into
ima_namespace).

/*
* IMA architecture specific policy rules are specified
* as strings and converted to an array of ima_entry_rules
* on boot.  After loading a custom policy, free the
* architecture specific rules stored as an array.
*/
kfree(arch_policy_entry);

So, I now added kfree(ns->arch_policy_entry).

Thanks.

Stefan

>
>> #define __ima_hook_stringify(func, str) (#func),
>>
>> const char *const func_tokens[] = {