Re: FAILED: patch "[PATCH] crypto: caam - strip input zeros from RSA input buffer" failed to apply to 4.9-stable tree

[Greg KH <gregkh@linuxfoundation.org>]

On Fri, Jun 15, 2018 at 09:07:24AM +0100, Martin Townsend wrote:
> On Thu, Jun 14, 2018 at 2:08 PM <gregkh@linuxfoundation.org> wrote:
> >
> >
> > The patch below does not apply to the 4.9-stable tree.
> > If someone wants it applied there, or to any other stable or longterm
> > tree, then please email the backport, including the original git commit
> > id to <stable@vger.kernel.org>.
> >
> > thanks,
> >
> > greg k-h
> >
> > ------------------ original commit in Linus's tree ------------------
> >
> > From 8a2a0dd35f2e54c023d9041a5428b6c5639af86c Mon Sep 17 00:00:00 2001
> > From: =?UTF-8?q?Horia=20Geant=C4=83?= <horia.geanta@nxp.com>
> > Date: Mon, 16 Apr 2018 08:07:05 -0500
> > Subject: [PATCH] crypto: caam - strip input zeros from RSA input buffer
> > MIME-Version: 1.0
> > Content-Type: text/plain; charset=UTF-8
> > Content-Transfer-Encoding: 8bit
> >
> > Sometimes the provided RSA input buffer provided is not stripped
> > of leading zeros. This could cause its size to be bigger than that
> > of the modulus, making the HW complain:
> >
> > caam_jr 2142000.jr1: 40000789: DECO: desc idx 7:
> > Protocol Size Error - A protocol has seen an error in size. When
> > running RSA, pdb size N < (size of F) when no formatting is used; or
> > pdb size N < (F + 11) when formatting is used.
> >
> > Fix the problem by stripping off the leading zero from input data
> > before feeding it to the CAAM accelerator.
> >
> > Fixes: 8c419778ab57e ("crypto: caam - add support for RSA algorithm")
> > Cc: <stable@vger.kernel.org> # 4.8+
> > Reported-by: Martin Townsend <mtownsend1973@gmail.com>
> > Link: https://lkml.kernel.org/r/CABatt_ytYORYKtApcB4izhNanEKkGFi9XAQMjHi_n-8YWoCRiw@mail.gmail.com
> > Signed-off-by: Horia Geantă <horia.geanta@nxp.com>
> > Tested-by: Fabio Estevam <fabio.estevam@nxp.com>
> > Reviewed-by: Tudor Ambarus <tudor.ambarus@microchip.com>
> > Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
> >
> > diff --git a/drivers/crypto/caam/caampkc.c b/drivers/crypto/caam/caampkc.c
> > index 7a897209f181..979072b25eaa 100644
> > --- a/drivers/crypto/caam/caampkc.c
> > +++ b/drivers/crypto/caam/caampkc.c
> > @@ -166,18 +166,71 @@ static void rsa_priv_f3_done(struct device *dev, u32 *desc, u32 err,
> >         akcipher_request_complete(req, err);
> >  }
> >
> > +static int caam_rsa_count_leading_zeros(struct scatterlist *sgl,
> > +                                       unsigned int nbytes,
> > +                                       unsigned int flags)
> > +{
> > +       struct sg_mapping_iter miter;
> > +       int lzeros, ents;
> > +       unsigned int len;
> > +       unsigned int tbytes = nbytes;
> > +       const u8 *buff;
> > +
> > +       ents = sg_nents_for_len(sgl, nbytes);
> > +       if (ents < 0)
> > +               return ents;
> > +
> > +       sg_miter_start(&miter, sgl, ents, SG_MITER_FROM_SG | flags);
> > +
> > +       lzeros = 0;
> > +       len = 0;
> > +       while (nbytes > 0) {
> > +               while (len && !*buff) {
> > +                       lzeros++;
> > +                       len--;
> > +                       buff++;
> > +               }
> > +
> > +               if (len && *buff)
> > +                       break;
> > +
> > +               sg_miter_next(&miter);
> > +               buff = miter.addr;
> > +               len = miter.length;
> > +
> > +               nbytes -= lzeros;
> > +               lzeros = 0;
> > +       }
> > +
> > +       miter.consumed = lzeros;
> > +       sg_miter_stop(&miter);
> > +       nbytes -= lzeros;
> > +
> > +       return tbytes - nbytes;
> > +}
> > +
> >  static struct rsa_edesc *rsa_edesc_alloc(struct akcipher_request *req,
> >                                          size_t desclen)
> >  {
> >         struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
> >         struct caam_rsa_ctx *ctx = akcipher_tfm_ctx(tfm);
> >         struct device *dev = ctx->dev;
> > +       struct caam_rsa_req_ctx *req_ctx = akcipher_request_ctx(req);
> >         struct rsa_edesc *edesc;
> >         gfp_t flags = (req->base.flags & CRYPTO_TFM_REQ_MAY_SLEEP) ?
> >                        GFP_KERNEL : GFP_ATOMIC;
> > +       int sg_flags = (flags == GFP_ATOMIC) ? SG_MITER_ATOMIC : 0;
> >         int sgc;
> >         int sec4_sg_index, sec4_sg_len = 0, sec4_sg_bytes;
> >         int src_nents, dst_nents;
> > +       int lzeros;
> > +
> > +       lzeros = caam_rsa_count_leading_zeros(req->src, req->src_len, sg_flags);
> > +       if (lzeros < 0)
> > +               return ERR_PTR(lzeros);
> > +
> > +       req->src_len -= lzeros;
> > +       req->src = scatterwalk_ffwd(req_ctx->src, req->src, lzeros);
> >
> >         src_nents = sg_nents_for_len(req->src, req->src_len);
> >         dst_nents = sg_nents_for_len(req->dst, req->dst_len);
> > @@ -953,6 +1006,7 @@ static struct akcipher_alg caam_rsa = {
> >         .max_size = caam_rsa_max_size,
> >         .init = caam_rsa_init_tfm,
> >         .exit = caam_rsa_exit_tfm,
> > +       .reqsize = sizeof(struct caam_rsa_req_ctx),
> >         .base = {
> >                 .cra_name = "rsa",
> >                 .cra_driver_name = "rsa-caam",
> > diff --git a/drivers/crypto/caam/caampkc.h b/drivers/crypto/caam/caampkc.h
> > index fd145c46eae1..82645bcf8b27 100644
> > --- a/drivers/crypto/caam/caampkc.h
> > +++ b/drivers/crypto/caam/caampkc.h
> > @@ -95,6 +95,14 @@ struct caam_rsa_ctx {
> >         struct device *dev;
> >  };
> >
> > +/**
> > + * caam_rsa_req_ctx - per request context.
> > + * @src: input scatterlist (stripped of leading zeros)
> > + */
> > +struct caam_rsa_req_ctx {
> > +       struct scatterlist src[2];
> > +};
> > +
> >  /**
> >   * rsa_edesc - s/w-extended rsa descriptor
> >   * @src_nents     : number of segments in input scatterlist
> >
> 
> 
> I have back ported this to 4.9 and have it running on an i.MX6UL
> board. I am happy to submit this if someone can tell me the best way
> to do this.

Just send it to stable@vger.kernel.org and say "here is the backport to
4.9 of commit id XXXX, can you please apply it?"

nothing fancy needed :)

thanks,

greg k-h