[PATCH] crypto: atmel-ecc - fix to allow multi segment scatterlists

[Tudor Ambarus]

Remove the limitation of single element scatterlists. ECDH with
multi-element scatterlists is needed by TPM.

Similar to 'commit 95ec01ba1ef0 ("crypto: ecdh - fix to allow multi
segment scatterlists")'.

Signed-off-by: Tudor Ambarus <tudor.amba...@microchip.com>
---
 drivers/crypto/atmel-ecc.c | 31 ++++++++++++++++++++++---------
 1 file changed, 22 insertions(+), 9 deletions(-)

diff --git a/drivers/crypto/atmel-ecc.c b/drivers/crypto/atmel-ecc.c
index e66f18a0..a25772e 100644
--- a/drivers/crypto/atmel-ecc.c
+++ b/drivers/crypto/atmel-ecc.c
@@ -186,7 +186,10 @@ static int atmel_ecc_init_ecdh_cmd(struct atmel_ecc_cmd 
*cmd,
         * always be the same. Use a macro for the key size to avoid unnecessary
         * computations.
         */
-       copied = sg_copy_to_buffer(pubkey, 1, cmd->data, ATMEL_ECC_PUBKEY_SIZE);
+       copied = sg_copy_to_buffer(pubkey,
+                                  sg_nents_for_len(pubkey,
+                                                   ATMEL_ECC_PUBKEY_SIZE),
+                                  cmd->data, ATMEL_ECC_PUBKEY_SIZE);
        if (copied != ATMEL_ECC_PUBKEY_SIZE)
                return -EINVAL;
 
@@ -268,15 +271,17 @@ static void atmel_ecdh_done(struct atmel_ecc_work_data 
*work_data, void *areq,
        struct kpp_request *req = areq;
        struct atmel_ecdh_ctx *ctx = work_data->ctx;
        struct atmel_ecc_cmd *cmd = &work_data->cmd;
-       size_t copied;
-       size_t n_sz = ctx->n_sz;
+       size_t copied, n_sz;
 
        if (status)
                goto free_work_data;
 
+       /* might want less than we've got */
+       n_sz = min_t(size_t, ctx->n_sz, req->dst_len);
+
        /* copy the shared secret */
-       copied = sg_copy_from_buffer(req->dst, 1, &cmd->data[RSP_DATA_IDX],
-                                    n_sz);
+       copied = sg_copy_from_buffer(req->dst, sg_nents_for_len(req->dst, n_sz),
+                                    &cmd->data[RSP_DATA_IDX], n_sz);
        if (copied != n_sz)
                status = -EINVAL;
 
@@ -440,7 +445,7 @@ static int atmel_ecdh_generate_public_key(struct 
kpp_request *req)
 {
        struct crypto_kpp *tfm = crypto_kpp_reqtfm(req);
        struct atmel_ecdh_ctx *ctx = kpp_tfm_ctx(tfm);
-       size_t copied;
+       size_t copied, nbytes;
        int ret = 0;
 
        if (ctx->do_fallback) {
@@ -448,10 +453,14 @@ static int atmel_ecdh_generate_public_key(struct 
kpp_request *req)
                return crypto_kpp_generate_public_key(req);
        }
 
+       /* might want less than we've got */
+       nbytes = min_t(size_t, ATMEL_ECC_PUBKEY_SIZE, req->dst_len);
+
        /* public key was saved at private key generation */
-       copied = sg_copy_from_buffer(req->dst, 1, ctx->public_key,
-                                    ATMEL_ECC_PUBKEY_SIZE);
-       if (copied != ATMEL_ECC_PUBKEY_SIZE)
+       copied = sg_copy_from_buffer(req->dst,
+                                    sg_nents_for_len(req->dst, nbytes),
+                                    ctx->public_key, nbytes);
+       if (copied != nbytes)
                ret = -EINVAL;
 
        return ret;
@@ -470,6 +479,10 @@ static int atmel_ecdh_compute_shared_secret(struct 
kpp_request *req)
                return crypto_kpp_compute_shared_secret(req);
        }
 
+       /* must have exactly two points to be on the curve */
+       if (req->src_len != ATMEL_ECC_PUBKEY_SIZE)
+               return -EINVAL;
+
        gfp = (req->base.flags & CRYPTO_TFM_REQ_MAY_SLEEP) ? GFP_KERNEL :
                                                             GFP_ATOMIC;
 
-- 
2.9.4