On Mon, Apr 16, 2018 at 10:34 AM, Horia Geantă <horia.geanta@xxxxxxx> wrote:
> 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@xxxxxxxxxxxxxxx> # 4.8+
> Reported-by: Martin Townsend <mtownsend1973@xxxxxxxxx>
> Link: https://lkml.kernel.org/r/CABatt_ytYORYKtApcB4izhNanEKkGFi9XAQMjHi_n-8YWoCRiw@xxxxxxxxxxxxxx
> Signed-off-by: Horia Geantă <horia.geanta@xxxxxxx>
> ---
> drivers/crypto/caam/caampkc.c | 54 +++++++++++++++++++++++++++++++++++++++++++
> drivers/crypto/caam/caampkc.h | 8 +++++++
> 2 files changed, 62 insertions(+)
>
> 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
> --
> 2.16.2
>
Using linux-imx 4.9 I can confirm that with the patch it boots to the
prompt and IMA/EVM is happily measuring files.
Tested-by: Martin Townsend <mtownsend1973@xxxxxxxxx>
