Messages in this thread | | | Date | Mon, 30 Jun 2008 20:43:20 +1000 (EST) | From | James Morris <> | Subject | Re: [RFC][PATCH 4/5] integrity: Linux Integrity Module(LIM) |
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On Fri, 27 Jun 2008, Mimi Zohar wrote:
> +const struct integrity_operations *integrity_ops = NULL;
This will be initialized to zero anyway.
> + > + if (!template_initialized++) > + INIT_LIST_HEAD(&integrity_templates);
Why not just intialize this at compile time with LIST_HEAD ?
> + template_len = strlen(template_name); > + if (template_len > TEMPLATE_NAME_LEN_MAX) > + template_len = TEMPLATE_NAME_LEN_MAX; > + memcpy(entry->template_name, template_name, template_len); > + entry->template_name[template_len] = '\0';
Perhaps this would be simpler if you just bail with -EINVAL if the length is too great. Then you can use strcpy and don't need to nul termiate the string for the caller.
> + rc = integrity_find_template(template_name, &template_ops); > + if (rc == 0) { > + rc = template_ops->collect_measurement(data); > + rcu_read_unlock(); > + return rc; > + } > + rcu_read_unlock(); > + return -EINVAL; > +}
If you give integrity_find_template() a standard form of returning 0 on success and -errno on failure, you can simplify the above quite a lot to have one unlock and one return.
> + int rc; > + > + rcu_read_lock(); > + rc = integrity_find_template(template_name, &template_ops); > + if (rc == 0) { > + rc = template_ops->appraise_measurement(data); > + rcu_read_unlock(); > + return rc; > + } > + rcu_read_unlock(); > + return -EINVAL; > +}
Ditto.
> + > +EXPORT_SYMBOL_GPL(integrity_appraise_measurement); > + > +/** > + * integrity_store_measurement - store template specific measurement > + * @template_name: a pointer to a string containing the template name. > + * @data: pointer to template specific data > + * > + * Store template specific integrity measurement. > + */ > +void integrity_store_measurement(const char *template_name, void *data) > +{ > + const struct template_operations *template_ops; > + int rc; > + > + rcu_read_lock(); > + rc = integrity_find_template(template_name, &template_ops); > + if (rc == 0) > + template_ops->store_measurement(data); > + rcu_read_unlock(); > + return; > +}
So, the caller does not get an error if they supply an invalid template name? That sounds like a bug which they need to know about.
> +/** > + * integrity_must_measure - measure decision based on template policy > + * @template_name: a pointer to a string containing the template name. > + * @data: pointer to template specific data > + * > + * Returns 0 on success, an error code on failure. > + */ > +int integrity_must_measure(const char *template_name, void *data) > +{ > + const struct template_operations *template_ops; > + int rc; > + > + rcu_read_lock(); > + rc = integrity_find_template(template_name, &template_ops); > + if (rc == 0) { > + rc = template_ops->must_measure(data); > + rcu_read_unlock(); > + return rc; > + } > + rcu_read_unlock(); > + return -EINVAL; > +}
Do a single unlock and return.
> +/* Hook used to measure executable file integrity. */ > +int integrity_bprm_check(struct linux_binprm *bprm) > +{ > + int rc = 0; > + > + if (integrity_ops && integrity_ops->bprm_check_integrity) > + rc = integrity_ops->bprm_check_integrity(bprm); > + return rc; > +}
Have you considered using a set of dummy ops similar to LSM, so that integrity_ops->whatever will always point to something and can be unconditionally called? (see security_fixup_ops()).
- James -- James Morris <jmorris@namei.org>
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