Am Donnerstag, 9. März 2017, 11:05:54 CET schrieb Herbert Xu:
Hi Herbert,
> On Thu, Mar 09, 2017 at 11:02:41AM +0100, Stephan Müller wrote:
> > > > The patch
> > > > 0001-crypto-algif_aead-copy-AAD-from-src-to-dst_separate.patch
> > > > simply copies the AAD over from TX SGL to RX SGL. The pro is that the
> > > > patch is small. The con is that this approach does *not* provide an
> > > > in-place crypto operation.
> > >
> > > I prefer this patch with the proviso that it copy the whole thing
> > > instead of just the AD. That way you can just feed the dst memory
> > > to crypto_aead for in-place operation. Of course you have to mangle
> > > the tag data onto the dst SG list for decryption but it shouldn't
> > > be too hard.
> >
> > I thought that is exactly the second patch. It copies the entire data to
> > the dst SGL and extends the SGL with the tag in case of decryption.
>
> Are you sure? The patch says:
>
> + /* copy AAD from src to dst */
> + err = crypto_aead_copy_sgl(ctx->null, areq->tsgl,
> + areq->first_rsgl.sgl.sg,
> ctx->aead_assoclen);
>
> Which seems to only copy the AD.
This is the first patch (0001-crypto-algif_aead-copy-AAD-from-src-to-
dst_separate.patch).
The second alternative patch (0001-crypto-algif_aead-copy-AAD-from-src-to-
dst_inplace.patch) does:
+ if (ctx->enc) {
+ /* Copy AAD || PT to RX SGL buffer for in-place operation. */
+ err = crypto_aead_copy_sgl(ctx->null, tsgl->sg,
+ areq->first_rsgl.sgl.sg, processed);
+ if (err)
+ goto free;
+ aead_pull_tsgl(sk, processed, NULL, 0);
+ } else {
+ /* Copy AAD || CT to RX SGL buffer for in-place operation. */
+ err = crypto_aead_copy_sgl(ctx->null, tsgl->sg,
+ areq->first_rsgl.sgl.sg, outlen);
+ if (err)
+ goto free;
+
+ /* Create TX SGL for tag and chain it to RX SGL. */
+ areq->tsgl_entries = aead_count_tsgl(sk, processed);
+ if (!areq->tsgl_entries)
+ areq->tsgl_entries = 1;
+ areq->tsgl = sock_kmalloc(sk, sizeof(*areq->tsgl) *
+ areq->tsgl_entries,
+ GFP_KERNEL);
+ if (!areq->tsgl) {
+ err = -ENOMEM;
+ goto free;
+ }
+ sg_init_table(areq->tsgl, areq->tsgl_entries);
+
+ /* Release TX SGL, except for tag data. */
+ aead_pull_tsgl(sk, processed, areq->tsgl, processed - as);
+
+ /* chain the areq TX SGL holding the tag with RX SGL */
+ if (!last_rsgl) {
+ /* no RX SGL present (e.g. only authentication) */
+ sg_init_table(areq->first_rsgl.sgl.sg, 2);
+ sg_chain(areq->first_rsgl.sgl.sg, 2, areq->tsgl);
+ } else {
+ /* RX SGL present */
+ struct af_alg_sgl *sgl_prev = &last_rsgl->sgl;
+
+ sg_unmark_end(sgl_prev->sg + sgl_prev->npages - 1);
+ sg_chain(sgl_prev->sg, sgl_prev->npages + 1,
areq->tsgl);
+ }
}
Ciao
Stephan
