| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-Id: <1228328102.2821.25.camel@localhost.localdomain>
Date: Wed, 03 Dec 2008 13:15:02 -0500
From: Mimi Zohar <zohar@...ux.vnet.ibm.com>
To: Dave Hansen <dave@...ux.vnet.ibm.com>
Cc: linux-kernel@...r.kernel.org,
Andrew Morton <akpm@...ux-foundation.org>,
James Morris <jmorris@...ei.org>,
Christoph Hellwig <hch@...radead.org>,
Al Viro <viro@...IV.linux.org.uk>,
David Safford <safford@...son.ibm.com>,
Serge Hallyn <serue@...ux.vnet.ibm.com>,
Mimi Zohar <zohar@...ibm.com>
Subject: Re: [PATCH 2/6] integrity: Linux Integrity Module(LIM)
On Tue, 2008-12-02 at 14:43 -0800, Dave Hansen wrote:
> On Tue, 2008-12-02 at 16:47 -0500, Mimi Zohar wrote:
> > +#endif
> > +#endif
>
> Personally, I love to see comments on these suckers after a long header
> file. My memory sucks.
ok
> > +int register_integrity(const struct integrity_operations *ops)
> > +{
> > + if (integrity_ops != NULL)
> > + return -EAGAIN;
> > + integrity_ops = ops;
> > + return 0;
> > +}
>
> Is there some locking to keep this from racing and two integrity modules
> both thinking they succeeded? Does it matter?
Wouldn't this be a Kconfig issue.
> > +/**
> > + * integrity_register_template - registers an integrity template with the kernel
> > + * @template_name: a pointer to a string containing the template name.
> > + * @template_ops: a pointer to the template functions
> > + *
> > + * Register a set of functions to collect, appraise, store, and display
> > + * a template measurement, and a means to decide whether to do them.
> > + * Unlike integrity modules, any number of templates may be registered.
> > + *
> > + * Returns 0 on success, an error code on failure.
> > + */
> > +int integrity_register_template(const char *template_name,
> > + const struct template_operations *template_ops)
> > +{
> > + int template_len;
> > + struct template_list_entry *entry;
> > +
> > + template_len = strlen(template_name);
> > + if (template_len > TEMPLATE_NAME_LEN_MAX)
> > + return -EINVAL;
> > +
> > + entry = kzalloc(sizeof(*entry), GFP_KERNEL);
> > + if (!entry)
> > + return -ENOMEM;
> > + INIT_LIST_HEAD(&entry->template);
> > +
> > + kref_set(&entry->refcount, 1);
> > + strcpy(entry->template_name, template_name);
> > + entry->template_ops = template_ops;
> > +
> > + mutex_lock(&integrity_templates_mutex);
> > + list_add_rcu(&entry->template, &integrity_templates);
> > + mutex_unlock(&integrity_templates_mutex);
> > + synchronize_rcu();
>
> What's the synchronize_rcu() for here?
good question.
> > +int integrity_unregister_template(const char *template_name)
> > +{
> > + struct template_list_entry *entry;
> > +
> > + mutex_lock(&integrity_templates_mutex);
> > + list_for_each_entry(entry, &integrity_templates, template) {
> > + if (strncmp(entry->template_name, template_name,
> > + strlen(entry->template_name)) == 0) {
> > + list_del_rcu(&entry->template);
> > + mutex_unlock(&integrity_templates_mutex);
> > + synchronize_rcu();
> > + kref_put(&entry->refcount, template_release);
> > + return 0;
> > + }
> > + }
> > + mutex_unlock(&integrity_templates_mutex);
> > + return -EINVAL;
> > +}
> > +EXPORT_SYMBOL_GPL(integrity_unregister_template);
>
> Is this frequently called? If so, it might be better to use
> call_rcu().
I don't expect that Templates would be added/removed frequently,
but I could be wrong. Only time will tell.
> > +/**
> > + * integrity_find_get_template - search the integrity_templates list
> > + * @template_name: a pointer to a string containing the template name.
> > + *
> > + * Returns a pointer to an entry in the template list on success, NULL
> > + * on failure.
> > + */
> > +struct template_list_entry *integrity_find_get_template(const char
> > + *template_name)
> > +{
> > + struct template_list_entry *entry, *template_entry = NULL;
> > +
> > + rcu_read_lock();
> > + list_for_each_entry_rcu(entry, &integrity_templates, template) {
> > + if (strncmp(entry->template_name, template_name,
> > + strlen(entry->template_name)) == 0) {
> > + template_entry = entry;
> > + break;
> > + }
> > + }
> > + if (template_entry)
> > + kref_get(&template_entry->refcount);
> > + rcu_read_unlock();
> > + return template_entry;
> > +}
>
> Is there a reason not to do the kref_get() inside the loop? Would save
> a line of code.
none, will do.
> > +int integrity_collect_measurement(const char *template_name, void *data)
> > +{
> > + struct template_list_entry *template_entry;
> > + int rc = -EINVAL;
> > +
> > + template_entry = integrity_find_get_template(template_name);
> > + if (template_entry) {
> > + rc = template_entry->template_ops->collect_measurement(data);
> > + kref_put(&template_entry->refcount, template_release);
> > + }
> > + return rc;
> > +}
> > +EXPORT_SYMBOL_GPL(integrity_collect_measurement);
> > +
>
> It's kinda a shame to see 5 or 6 functions which are such carbon copies
> of each other. Could you do one of these, and just pass in the ops
> function as well as 'data'?
>
> You would have one of these:
>
> +int integrity_generic_template(const char *template_name,
> + void (*func)(void *data), void *data)
> +{
> + struct template_list_entry *template_entry;
> + int rc = -EINVAL;
> +
> + template_entry = integrity_find_get_template(template_name);
> + if (template_entry) {
> + rc = func(data);
> + kref_put(&template_entry->refcount, template_release);
> + }
> + return rc;
> +}
>
> And each measurement function could be something silly like:
>
> int integrity_collect_measurement(const char *template_name, void *data)
> {
> return integrity_generic_template(template_name,
> template_entry->template_ops->collect_measurement,
> data);
> }
>
> -- Dave
Yes, will re-factor the code. Thanks!
Mimi
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists