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

Mimi Zohar
2022-02-18T17:12:02Z

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().

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

--
thanks,

Mimi