drivers: crypto: Add multipart hash support

Add a new API to support multipart hash calculation. The API allows
split the data input to be split in small chunks.

Signed-off-by: Flavio Ceolin <flavio.ceolin@intel.com>

Author: Flavio Ceolin

drivers/crypto/crypto_mtls_shim.c

@@ -462,55 +462,72 @@ static int mtls_session_free(const struct device *dev, struct cipher_ctx *ctx)
 	return 0;
 }
 
-static int mtls_sha256_compute(struct hash_ctx *ctx, struct hash_pkt *pkt)
+static int mtls_sha256_compute(struct hash_ctx *ctx, struct hash_pkt *pkt,
+			       bool finish)
 {
 	int ret;
 	mbedtls_sha256_context *sha256_ctx = MTLS_GET_CTX(ctx, sha256);
 
 
-	ret = mbedtls_sha256_starts(sha256_ctx,
-			    MTLS_GET_ALGO(ctx) == CRYPTO_HASH_ALGO_SHA224);
-	if (ret != 0) {
-		LOG_ERR("Could not compute the hash");
-		return -EINVAL;
+	if (!ctx->started) {
+		ret = mbedtls_sha256_starts(sha256_ctx,
+					    MTLS_GET_ALGO(ctx) == CRYPTO_HASH_ALGO_SHA224);
+		if (ret != 0) {
+			LOG_ERR("Could not compute the hash");
+			return -EINVAL;
+		}
+		ctx->started = true;
 	}
 
 	ret = mbedtls_sha256_update(sha256_ctx, pkt->in_buf, pkt->in_len);
 	if (ret != 0) {
-		LOG_ERR("Could not compute the hash");
+		LOG_ERR("Could not update the hash");
+		ctx->started = false;
 		return -EINVAL;
 	}
 
-	ret = mbedtls_sha256_finish(sha256_ctx, pkt->out_buf);
-	if (ret != 0) {
-		LOG_ERR("Could not compute the hash");
-		return -EINVAL;
+	if (finish) {
+		ctx->started = false;
+		ret = mbedtls_sha256_finish(sha256_ctx, pkt->out_buf);
+		if (ret != 0) {
+			LOG_ERR("Could not compute the hash");
+			return -EINVAL;
+		}
 	}
 
 	return 0;
 }
 
-static int mtls_sha512_compute(struct hash_ctx *ctx, struct hash_pkt *pkt)
+static int mtls_sha512_compute(struct hash_ctx *ctx, struct hash_pkt *pkt,
+			       bool finish)
 {
 	int ret;
 	mbedtls_sha512_context *sha512_ctx = MTLS_GET_CTX(ctx, sha512);
 
-	ret = mbedtls_sha512_starts(sha512_ctx,
-			    MTLS_GET_ALGO(ctx) == CRYPTO_HASH_ALGO_SHA384);
-	if (ret != 0) {
-		LOG_ERR("Could not compute the hash");
-		return -EINVAL;
+	if (!ctx->started) {
+		ret = mbedtls_sha512_starts(sha512_ctx,
+					    MTLS_GET_ALGO(ctx) == CRYPTO_HASH_ALGO_SHA384);
+		if (ret != 0) {
+			LOG_ERR("Could not compute the hash");
+			return -EINVAL;
+		}
+		ctx->started = true;
 	}
+
 	ret = mbedtls_sha512_update(sha512_ctx, pkt->in_buf, pkt->in_len);
 	if (ret != 0) {
-		LOG_ERR("Could not compute the hash");
+		LOG_ERR("Could not update the hash");
+		ctx->started = false;
 		return -EINVAL;
 	}
 
-	ret = mbedtls_sha512_finish(sha512_ctx, pkt->out_buf);
-	if (ret != 0) {
-		LOG_ERR("Could not compute the hash");
-		return -EINVAL;
+	if (finish) {
+		ctx->started = false;
+		ret = mbedtls_sha512_finish(sha512_ctx, pkt->out_buf);
+		if (ret != 0) {
+			LOG_ERR("Could not compute the hash");
+			return -EINVAL;
+		}
 	}
 
 	return 0;
@@ -543,6 +560,7 @@ static int mtls_hash_session_setup(const struct device *dev,
 
 	mtls_sessions[ctx_idx].algo = algo;
 	ctx->drv_sessn_state = &mtls_sessions[ctx_idx];
+	ctx->started = false;
 
 	if ((algo == CRYPTO_HASH_ALGO_SHA224) ||
 	    (algo == CRYPTO_HASH_ALGO_SHA256)) {

include/crypto/crypto.h

@@ -465,9 +465,27 @@ static inline int hash_compute(struct hash_ctx *ctx, struct hash_pkt *pkt)
 {
 	pkt->ctx = ctx;
 
-	return ctx->hash_hndlr(ctx, pkt);
+	return ctx->hash_hndlr(ctx, pkt, true);
 }
 
+/**
+ * @brief Perform  a cryptographic multipart hash operation.
+ *
+ * This function can be called zero or more times, passing a slice of the
+ * the data. The hash is calculated using all the given pieces.
+ * To calculate the hash call @c hash_compute().
+ *
+ * @param  ctx       Pointer to the hash context of this op.
+ * @param  pkt       Structure holding the input.
+
+ * @return 0 on success, negative errno code on fail.
+ */
+static inline int hash_update(struct hash_ctx *ctx, struct hash_pkt *pkt)
+{
+	pkt->ctx = ctx;
+
+	return ctx->hash_hndlr(ctx, pkt, false);
+}
 
 /**
  * @}

include/crypto/hash.h

@@ -35,7 +35,8 @@ struct hash_ctx;
 struct hash_pkt;
 
 
-typedef int (*hash_op_t)(struct hash_ctx *ctx, struct hash_pkt *pkt);
+typedef int (*hash_op_t)(struct hash_ctx *ctx, struct hash_pkt *pkt,
+			 bool finish);
 
 /**
  * Structure encoding session parameters.
@@ -63,6 +64,11 @@ struct hash_ctx {
 	 */
 	hash_op_t hash_hndlr;
 
+	/**
+	 * If it has started a multipart hash operation.
+	 */
+	bool started;
+
 	/** How certain fields are to be interpreted for this session.
 	 * (A bitmask of CAP_* below.)
 	 * To be populated by the app before calling hash_begin_session().