crypto: atmel-sha - Add zero length message digest support for hmac

Add softare padding to hmac-sha digest for zero length messages.
Using the atmel_sha_fill_padding() to fill the buffer with a padded
empty message with a length of the block size.

Create a temporary scatter list from the padded buffer to pass into the
data processing functions.

Signed-off-by: Ryan Wanner <Ryan.Wanner@microchip.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/drivers/crypto/atmel-sha.c b/drivers/crypto/atmel-sha.c
index e7c1db2..6bef634 100644 (file)
--- a/drivers/crypto/atmel-sha.c
+++ b/drivers/crypto/atmel-sha.c
@@ -1948,14 +1948,32 @@ static int atmel_sha_hmac_digest2(struct atmel_sha_dev *dd)
        struct atmel_sha_reqctx *ctx = ahash_request_ctx(req);
        struct crypto_ahash *tfm = crypto_ahash_reqtfm(req);
        struct atmel_sha_hmac_ctx *hmac = crypto_ahash_ctx(tfm);
+       struct scatterlist *sgbuf;
        size_t hs = ctx->hash_size;
        size_t i, num_words = hs / sizeof(u32);
        bool use_dma = false;
        u32 mr;
 
        /* Special case for empty message. */
-       if (!req->nbytes)
-               return atmel_sha_complete(dd, -EINVAL); // TODO:
+       if (!req->nbytes) {
+               req->nbytes = 0;
+               ctx->bufcnt = 0;
+               ctx->digcnt[0] = 0;
+               ctx->digcnt[1] = 0;
+               switch (ctx->flags & SHA_FLAGS_ALGO_MASK) {
+               case SHA_FLAGS_SHA1:
+               case SHA_FLAGS_SHA224:
+               case SHA_FLAGS_SHA256:
+                       atmel_sha_fill_padding(ctx, 64);
+                       break;
+
+               case SHA_FLAGS_SHA384:
+               case SHA_FLAGS_SHA512:
+                       atmel_sha_fill_padding(ctx, 128);
+                       break;
+               }
+               sg_init_one(&dd->tmp, ctx->buffer, ctx->bufcnt);
+       }
 
        /* Check DMA threshold and alignment. */
        if (req->nbytes > ATMEL_SHA_DMA_THRESHOLD &&
@@ -1985,12 +2003,20 @@ static int atmel_sha_hmac_digest2(struct atmel_sha_dev *dd)
 
        atmel_sha_write(dd, SHA_CR, SHA_CR_FIRST);
 
+       /* Special case for empty message. */
+       if (!req->nbytes) {
+               sgbuf = &dd->tmp;
+               req->nbytes = ctx->bufcnt;
+       } else {
+               sgbuf = req->src;
+       }
+
        /* Process data. */
        if (use_dma)
-               return atmel_sha_dma_start(dd, req->src, req->nbytes,
+               return atmel_sha_dma_start(dd, sgbuf, req->nbytes,
                                           atmel_sha_hmac_final_done);
 
-       return atmel_sha_cpu_start(dd, req->src, req->nbytes, false, true,
+       return atmel_sha_cpu_start(dd, sgbuf, req->nbytes, false, true,
                                   atmel_sha_hmac_final_done);
 }