crypto: algif_skcipher - Use chunksize instead of blocksize

When algif_skcipher does a partial operation it always process data
that is a multiple of blocksize.  However, for algorithms such as
CTR this is wrong because even though it can process any number of
bytes overall, the partial block must come at the very end and not
in the middle.

This is exactly what chunksize is meant to describe so this patch
changes blocksize to chunksize.

Fixes: 8ff590903d5f ("crypto: algif_skcipher - User-space...")
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 30 insertions, 0 deletions

diff --git a/include/crypto/skcipher.h b/include/crypto/skcipher.h
index 37c164234d97..aada87916918 100644
--- a/include/crypto/skcipher.h
+++ b/include/crypto/skcipher.h
@@ -304,6 +304,36 @@ static inline unsigned int crypto_skcipher_blocksize(
 	return crypto_tfm_alg_blocksize(crypto_skcipher_tfm(tfm));
 }
 
+static inline unsigned int crypto_skcipher_alg_chunksize(
+	struct skcipher_alg *alg)
+{
+	if ((alg->base.cra_flags & CRYPTO_ALG_TYPE_MASK) ==
+	    CRYPTO_ALG_TYPE_BLKCIPHER)
+		return alg->base.cra_blocksize;
+
+	if (alg->base.cra_ablkcipher.encrypt)
+		return alg->base.cra_blocksize;
+
+	return alg->chunksize;
+}
+
+/**
+ * crypto_skcipher_chunksize() - obtain chunk size
+ * @tfm: cipher handle
+ *
+ * The block size is set to one for ciphers such as CTR.  However,
+ * you still need to provide incremental updates in multiples of
+ * the underlying block size as the IV does not have sub-block
+ * granularity.  This is known in this API as the chunk size.
+ *
+ * Return: chunk size in bytes
+ */
+static inline unsigned int crypto_skcipher_chunksize(
+	struct crypto_skcipher *tfm)
+{
+	return crypto_skcipher_alg_chunksize(crypto_skcipher_alg(tfm));
+}
+
 static inline unsigned int crypto_sync_skcipher_blocksize(
 	struct crypto_sync_skcipher *tfm)
 {