Re: [PATCH v7 1/2] crypto: AF_ALG: add AEAD support

Am Montag, 5. Januar 2015, 21:51:06 schrieb Herbert Xu:

Hi Herbert,

On Mon, Jan 05, 2015 at 11:46:50AM +0100, Stephan Mueller wrote:

quoted

The need for that check lies in aead_recvmsg:
        /*
        
         * first chunk of input is AD -- one scatterlist entry is one
         page,
         * and we process only one scatterlist, the maximum size of AD is
         * one page
         */
        
        sg_init_table(&assoc, 1);
        sg_set_page(&assoc, sg_page(sg), ctx->aead_assoclen, sg->offset);
        aead_request_set_assoc(&ctx->aead_req, &assoc,
        ctx->aead_assoclen);

There you see that I only create an sg table with one entry for the AD. If
we would allow an arbitrary AD size, I would see the need of a for loop
in addition to the one directly beneath this AD scatterlist setting: one
for identifying how many sg entries I need to allocate and one for the
actual assignment.

As I felt that one page should be sufficient for the AD, I wanted to avoid
the extra overhead for another for loop.

Please remove the limit as otherwise we would never be able to
add support for this in a future kernel as appliations won't be
able to rely on it.

There is no such limit in the kernel interface and we shouldn't
be adding one here.

Ok, will do.

Cheers,

-- 
Ciao
Stephan