crypto/hash-afalg: Implement new hash API

Updates the afalg hash driver to support the new accumulative
hashing changes as part of the patch series.

Implements opening/closing of contexts, updating hash data
and finalizing the hash digest.

In order to support the update function, a flag needs to be passed
to the kernel via the socket send call (MSG_MORE) to notify it that more
data is to be expected to calculate the hash correctly.
As a result, a new function was added to the iov helper utils to allow
passing a flag to the socket send call.

Signed-off-by: Alejandro Zeise <alejandro.zeise@seagate.com>
[ clg: - Handled qcrypto_afalg_hash_ctx_new() errors in
         qcrypto_afalg_hash_new()
       - Freed alg_name in qcrypto_afalg_hash_new()
       - Reworked qcrypto_afalg_recv_from_kernel()
       - Split iov changes from original patch ]
Signed-off-by: Cédric Le Goater <clg@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

crypto/hash-afalg.c

@@ -1,6 +1,7 @@
 /*
  * QEMU Crypto af_alg-backend hash/hmac support
  *
+ * Copyright (c) 2024 Seagate Technology LLC and/or its Affiliates
  * Copyright (c) 2017 HUAWEI TECHNOLOGIES CO., LTD.
  *
  * Authors:
@@ -113,6 +114,128 @@ qcrypto_afalg_hmac_ctx_new(QCryptoHashAlgo alg,
     return qcrypto_afalg_hash_hmac_ctx_new(alg, key, nkey, true, errp);
 }
 
+static
+QCryptoHash *qcrypto_afalg_hash_new(QCryptoHashAlgo alg, Error **errp)
+{
+    /* Check if hash algorithm is supported */
+    char *alg_name = qcrypto_afalg_hash_format_name(alg, false, NULL);
+    QCryptoHash *hash;
+
+    if (alg_name == NULL) {
+        error_setg(errp, "Unknown hash algorithm %d", alg);
+        return NULL;
+    }
+
+    g_free(alg_name);
+
+    hash = g_new(QCryptoHash, 1);
+    hash->alg = alg;
+    hash->opaque = qcrypto_afalg_hash_ctx_new(alg, errp);
+    if (!hash->opaque) {
+        free(hash);
+        return NULL;
+    }
+
+    return hash;
+}
+
+static
+void qcrypto_afalg_hash_free(QCryptoHash *hash)
+{
+    QCryptoAFAlg *ctx = hash->opaque;
+
+    if (ctx) {
+        qcrypto_afalg_comm_free(ctx);
+    }
+
+    g_free(hash);
+}
+
+/**
+ * Send data to the kernel's crypto core.
+ *
+ * The more_data parameter is used to notify the crypto engine
+ * that this is an "update" operation, and that more data will
+ * be provided to calculate the final hash.
+ */
+static
+int qcrypto_afalg_send_to_kernel(QCryptoAFAlg *afalg,
+                                 const struct iovec *iov,
+                                 size_t niov,
+                                 bool more_data,
+                                 Error **errp)
+{
+    int ret = 0;
+    int flags = (more_data ? MSG_MORE : 0);
+
+    /* send data to kernel's crypto core */
+    ret = iov_send_recv_with_flags(afalg->opfd, flags, iov, niov,
+                                   0, iov_size(iov, niov), true);
+    if (ret < 0) {
+        error_setg_errno(errp, errno, "Send data to afalg-core failed");
+        ret = -1;
+    } else {
+        /* No error, so return 0 */
+        ret = 0;
+    }
+
+    return ret;
+}
+
+static
+int qcrypto_afalg_recv_from_kernel(QCryptoAFAlg *afalg,
+                                   QCryptoHashAlgo alg,
+                                   uint8_t **result,
+                                   size_t *result_len,
+                                   Error **errp)
+{
+    struct iovec outv;
+    int ret;
+    const int expected_len = qcrypto_hash_digest_len(alg);
+
+    if (*result_len == 0) {
+        *result_len = expected_len;
+        *result = g_new0(uint8_t, *result_len);
+    } else if (*result_len != expected_len) {
+        error_setg(errp,
+                   "Result buffer size %zu is not match hash %d",
+                   *result_len, expected_len);
+        return -1;
+    }
+
+    /* hash && get result */
+    outv.iov_base = *result;
+    outv.iov_len = *result_len;
+    ret = iov_send_recv(afalg->opfd, &outv, 1,
+                        0, iov_size(&outv, 1), false);
+    if (ret < 0) {
+        error_setg_errno(errp, errno, "Recv result from afalg-core failed");
+        return -1;
+    }
+
+    return 0;
+}
+
+static
+int qcrypto_afalg_hash_update(QCryptoHash *hash,
+                              const struct iovec *iov,
+                              size_t niov,
+                              Error **errp)
+{
+    return qcrypto_afalg_send_to_kernel((QCryptoAFAlg *) hash->opaque,
+                                        iov, niov, true, errp);
+}
+
+static
+int qcrypto_afalg_hash_finalize(QCryptoHash *hash,
+                                 uint8_t **result,
+                                 size_t *result_len,
+                                 Error **errp)
+{
+    return qcrypto_afalg_recv_from_kernel((QCryptoAFAlg *) hash->opaque,
+                                          hash->alg, result, result_len, errp);
+}
+
 static int
 qcrypto_afalg_hash_hmac_bytesv(QCryptoAFAlgo *hmac,
                                QCryptoHashAlgo alg,
@@ -205,6 +328,10 @@ static void qcrypto_afalg_hmac_ctx_free(QCryptoHmac *hmac)
 
 QCryptoHashDriver qcrypto_hash_afalg_driver = {
     .hash_bytesv = qcrypto_afalg_hash_bytesv,
+    .hash_new      = qcrypto_afalg_hash_new,
+    .hash_free     = qcrypto_afalg_hash_free,
+    .hash_update   = qcrypto_afalg_hash_update,
+    .hash_finalize = qcrypto_afalg_hash_finalize
 };
 
 QCryptoHmacDriver qcrypto_hmac_afalg_driver = {