On 04/16/2018 04:07 PM, Horia Geantă 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> --- (Hopefully this one will reach the mailing list. Sorry for the noise, problems with SMTP.) 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);
This is interesting, you are overwriting the request's src sg. I kept wondering if one could have a problem if we are modifying its src sg. I couldn't find any failing scenario, so: Reviewed-by: Tudor Ambarus <tudor.ambarus@xxxxxxxxxxxxx>
