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

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Message-ID: <15ff4fc5b4386e588c4314ad9712b7044c0bb8f8.camel@linux.ibm.com>
Date:   Fri, 18 Feb 2022 15:04:18 -0500
From:   Mimi Zohar <zohar@...ux.ibm.com>
To:     Stefan Berger <stefanb@...ux.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 v10 16/27] ima: Implement ima_free_policy_rules() for
 freeing of an ima_namespace

On Fri, 2022-02-18 at 14:38 -0500, Stefan Berger wrote:
> 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.

ima_free_policy_rules() isn't free all the rules, just the custom
policy rules.  I would update the patch description as:

Implement ima_free_policy_rules() to free the custom policy rules, when
...

Otherwise,

Reviewd-by: Mimi Zohar <zohar@...ux.ibm.com>

> >>
> >> Signed-off-by: Stefan Berger <stefanb@...ux.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).

Yes, that is fine.

-- 
thanks,

Mimi