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

[Stefan Berger]

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@xxxxxxxxxxxxx>
> >
> > ---
> > 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[] = {