Re: [PATCH] Keys: Add LSM hooks for key management

[serue@us.ibm.com]

> +int key_task_permission(const key_ref_t key_ref,
> +			struct task_struct *context,
> +			key_perm_t perm)
> +{
> +	struct key *key;
> +	key_perm_t kperm;
> +	int ret;
> +
> +	/* let the security module have first say
> +	 * - it should return:
> +	 *	+ve to grant access
> +	 *	0   to deny access
> +	 *	-ve to fall back to normal permission checking
> +	 */
> +	ret = security_key_permission(key_ref, context, perm);
> +	if (ret >= 0)
> +		return ret;

Hmm, my only problem here is that this is nonstandard compared to
expected return values from other security_ authorization hooks.
Could this be switched to

	-ve : deny access (and return the error)
	0: grant access
	+ve: fall back to normal permission checking

Actually that's still nonstandard.  On the whole, LSM only
restricts, does not authorize, with capable() being the notable
exception.  Is there good reason to allow LSMs to fully authorize
in this case?

thanks,
-serge