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);
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
