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

Mimi Zohar
2022-01-28T14:03:41Z

Hi Stefan,

On Tue, 2022-01-25 at 17:46 -0500, Stefan Berger wrote:
> From: Stefan Berger <stefanb@linux.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.

>
> Signed-off-by: Stefan Berger <stefanb@linux.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?

> +
> + 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