Implement a EVP_PKEY KDF to KDF provider bridge

Some KDF implementations were available before the current EVP_KDF API.
They were used via EVP_PKEY_derive. There exists a bridge between the old
API and the EVP_KDF API however this bridge itself uses a legacy
EVP_PKEY_METHOD. This commit implements a provider side bridge without
having to use any legacy code.

Reviewed-by: Paul Dale <paul.dale@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/12573)

2 files changed, 151 insertions, 0 deletions

diff --git a/providers/implementations/exchange/build.info b/providers/implementations/exchange/build.info
index 3127f9a3e7..92932b9d28 100644
--- a/providers/implementations/exchange/build.info
+++ b/providers/implementations/exchange/build.info
@@ -4,6 +4,7 @@
 $DH_GOAL=../../libimplementations.a
 $ECX_GOAL=../../libimplementations.a
 $ECDH_GOAL=../../libimplementations.a
+$KDF_GOAL=../../libimplementations.a
 
 IF[{- !$disabled{dh} -}]
   SOURCE[$DH_GOAL]=dh_exch.c
@@ -25,3 +26,5 @@ IF[{- !$disabled{ec} -}]
   SOURCE[../../libfips.a]=ecdh_exch.c
   SOURCE[../../libnonfips.a]=ecdh_exch.c
 ENDIF
+
+SOURCE[$KDF_GOAL]=kdf_exch.c
diff --git a/providers/implementations/exchange/kdf_exch.c b/providers/implementations/exchange/kdf_exch.c
new file mode 100644
index 0000000000..41278e6389
--- /dev/null
+++ b/providers/implementations/exchange/kdf_exch.c
@@ -0,0 +1,148 @@
+/*
+ * Copyright 2020 The OpenSSL Project Authors. All Rights Reserved.
+ *
+ * Licensed under the Apache License 2.0 (the "License").  You may not use
+ * this file except in compliance with the License.  You can obtain a copy
+ * in the file LICENSE in the source distribution or at
+ * https://www.openssl.org/source/license.html
+ */
+
+#include <openssl/crypto.h>
+#include <openssl/kdf.h>
+#include <openssl/core_dispatch.h>
+#include <openssl/core_names.h>
+#include <openssl/params.h>
+#include "prov/implementations.h"
+#include "prov/provider_ctx.h"
+#include "prov/kdfexchange.h"
+
+static OSSL_FUNC_keyexch_newctx_fn kdf_newctx;
+static OSSL_FUNC_keyexch_init_fn kdf_init;
+static OSSL_FUNC_keyexch_derive_fn kdf_derive;
+static OSSL_FUNC_keyexch_freectx_fn kdf_freectx;
+static OSSL_FUNC_keyexch_dupctx_fn kdf_dupctx;
+static OSSL_FUNC_keyexch_set_ctx_params_fn kdf_set_ctx_params;
+static OSSL_FUNC_keyexch_settable_ctx_params_fn kdf_settable_ctx_params;
+
+typedef struct {
+    void *provctx;
+    EVP_KDF_CTX *kdfctx;
+    KDF_DATA *kdfdata;
+} PROV_KDF_CTX;
+
+static void *kdf_newctx(void *provctx)
+{
+    PROV_KDF_CTX *kdfctx = OPENSSL_zalloc(sizeof(PROV_KDF_CTX));
+    EVP_KDF *kdf = NULL;
+
+    if (kdfctx == NULL)
+        return NULL;
+
+    kdfctx->provctx = provctx;
+
+    kdf = EVP_KDF_fetch(PROV_LIBRARY_CONTEXT_OF(provctx), "TLS1-PRF", NULL);
+    if (kdf == NULL)
+        goto err;
+    kdfctx->kdfctx = EVP_KDF_new_ctx(kdf);
+    EVP_KDF_free(kdf);
+
+    if (kdfctx->kdfctx == NULL)
+        goto err;
+
+    return kdfctx;
+ err:
+    OPENSSL_free(kdfctx);
+    return NULL;
+}
+
+static int kdf_init(void *vpkdfctx, void *vkdf)
+{
+    PROV_KDF_CTX *pkdfctx = (PROV_KDF_CTX *)vpkdfctx;
+
+    if (pkdfctx == NULL || vkdf == NULL || !kdf_data_up_ref(vkdf))
+        return 0;
+    pkdfctx->kdfdata = vkdf;
+
+    return 1;
+}
+
+static int kdf_derive(void *vpkdfctx, unsigned char *secret, size_t *secretlen,
+                      size_t outlen)
+{
+    PROV_KDF_CTX *pkdfctx = (PROV_KDF_CTX *)vpkdfctx;
+
+    return EVP_KDF_derive(pkdfctx->kdfctx, secret, *secretlen);
+}
+
+static void kdf_freectx(void *vpkdfctx)
+{
+    PROV_KDF_CTX *pkdfctx = (PROV_KDF_CTX *)vpkdfctx;
+
+    EVP_KDF_CTX_free(pkdfctx->kdfctx);
+    kdf_data_free(pkdfctx->kdfdata);
+
+    OPENSSL_free(pkdfctx);
+}
+
+static void *kdf_dupctx(void *vpkdfctx)
+{
+    PROV_KDF_CTX *srcctx = (PROV_KDF_CTX *)vpkdfctx;
+    PROV_KDF_CTX *dstctx;
+
+    dstctx = OPENSSL_zalloc(sizeof(*srcctx));
+    if (dstctx == NULL)
+        return NULL;
+
+    *dstctx = *srcctx;
+
+    dstctx->kdfctx = EVP_KDF_dup_ctx(srcctx->kdfctx);
+    if (dstctx->kdfctx == NULL) {
+        OPENSSL_free(dstctx);
+        return NULL;
+    }
+    if (!kdf_data_up_ref(dstctx->kdfdata)) {
+        EVP_KDF_CTX_free(dstctx->kdfctx);
+        OPENSSL_free(dstctx);
+        return NULL;
+    }
+
+    return dstctx;
+}
+
+static int kdf_set_ctx_params(void *vpkdfctx, const OSSL_PARAM params[])
+{
+    PROV_KDF_CTX *pkdfctx = (PROV_KDF_CTX *)vpkdfctx;
+
+    return EVP_KDF_set_ctx_params(pkdfctx->kdfctx, params);
+}
+
+
+static const OSSL_PARAM *kdf_settable_ctx_params(void)
+{
+    /*
+     * TODO(3.0): FIXME FIXME!! These settable_ctx_params functions should
+     * should have a provctx argument so we can get hold of the libctx.
+     */
+    EVP_KDF *kdf = EVP_KDF_fetch(NULL, "TLS1-PRF", NULL);
+    const OSSL_PARAM *params;
+
+    if (kdf == NULL)
+        return NULL;
+
+    params = EVP_KDF_settable_ctx_params(kdf);
+    EVP_KDF_free(kdf);
+
+    return params;
+}
+
+const OSSL_DISPATCH kdf_keyexch_functions[] = {
+    { OSSL_FUNC_KEYEXCH_NEWCTX, (void (*)(void))kdf_newctx },
+    { OSSL_FUNC_KEYEXCH_INIT, (void (*)(void))kdf_init },
+    { OSSL_FUNC_KEYEXCH_DERIVE, (void (*)(void))kdf_derive },
+    { OSSL_FUNC_KEYEXCH_FREECTX, (void (*)(void))kdf_freectx },
+    { OSSL_FUNC_KEYEXCH_DUPCTX, (void (*)(void))kdf_dupctx },
+    { OSSL_FUNC_KEYEXCH_SET_CTX_PARAMS, (void (*)(void))kdf_set_ctx_params },
+    { OSSL_FUNC_KEYEXCH_SETTABLE_CTX_PARAMS,
+      (void (*)(void))kdf_settable_ctx_params },
+    { 0, NULL }
+};