Re: [PATCH] Stacker - single-use static slots

[Chris Wright]

* serue@xxxxxxxxxx (serue@xxxxxxxxxx) wrote:
> > James had suggested to effectively stash the list in the last slot, so
> > there's only the array with one reserved slot.
> 
> Oh, I didn't catch that.  I like it.  Will do.
> 
> So you mean 3 slots total including the shared one?

Yeah, i.e. common case is $LSM and capabilities.  Stack slot is last
one, and gets put to use only if needed.

> Any comments on the added argument to register_security and
> mod_reg_security to request a static slot?

Why would you not request a static slot?

> +	spin_lock(&security_field_spinlock);
> +	if (idx && *idx) {
> +		int i;
> +
> +		*idx = -1;

So, I guess this means you request one, but who knows which one you'll
get?

> +		for (i=0; i<CONFIG_SECURITY_STACKER_NUMFIELDS; i++) {
> +			if (security_field_owners[i] == NULL) {
> +				security_field_owners[i] = ops;
> +				*idx = i;
> +				break;
> +			}
> +		}
> +	}
> +	spin_unlock(&security_field_spinlock);

> Given the likelyhood of
> capability/cap_stack being registered, it seemed worthwhile not to have
> it waste a spot, but it is an API change...

API change is no big deal.  Seems useful to get index value so you can
do optimized retrieve later.  But, I don't see it useful to request that
way.  Just register, get index, if index == last slot, lookup hits list.

thanks,
-chris
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