Implement provider-side keymgmt_dup function

To avoid mutating key data add OSSL_FUNC_KEYMGMT_DUP function
to the provider API and implement it for all asym-key key
managements.

Use it when copying everything to an empty EVP_PKEY
which is the case with EVP_PKEY_dup().

Fixes #14658

Reviewed-by: Shane Lontis <shane.lontis@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/14793)

3 files changed, 47 insertions, 41 deletions

diff --git a/crypto/dh/dh_ameth.c b/crypto/dh/dh_ameth.c
index 907a867eca..1e72561d25 100644
--- a/crypto/dh/dh_ameth.c
+++ b/crypto/dh/dh_ameth.c
@@ -536,46 +536,6 @@ static int dhx_pkey_import_from(const OSSL_PARAM params[], void *vpctx)
     return dh_pkey_import_from_type(params, vpctx, EVP_PKEY_DHX);
 }
 
-static ossl_inline int dh_bn_dup_check(BIGNUM **out, const BIGNUM *f)
-{
-    if (f != NULL && (*out = BN_dup(f)) == NULL)
-        return 0;
-    return 1;
-}
-
-static DH *dh_dup(const DH *dh)
-{
-    DH *dupkey = NULL;
-
-    /* Do not try to duplicate foreign DH keys */
-    if (ossl_dh_get_method(dh) != DH_OpenSSL())
-        return NULL;
-
-    if ((dupkey = ossl_dh_new_ex(dh->libctx)) == NULL)
-        return NULL;
-
-    dupkey->length = DH_get_length(dh);
-    if (!ossl_ffc_params_copy(&dupkey->params, &dh->params))
-        goto err;
-
-    dupkey->flags = dh->flags;
-
-    if (!dh_bn_dup_check(&dupkey->pub_key, dh->pub_key))
-        goto err;
-    if (!dh_bn_dup_check(&dupkey->priv_key, dh->priv_key))
-        goto err;
-
-    if (!CRYPTO_dup_ex_data(CRYPTO_EX_INDEX_DH,
-                            &dupkey->ex_data, &dh->ex_data))
-        goto err;
-
-    return dupkey;
-
- err:
-    DH_free(dupkey);
-    return NULL;
-}
-
 static int dh_pkey_copy(EVP_PKEY *to, EVP_PKEY *from)
 {
     DH *dh = from->pkey.dh;
@@ -583,7 +543,7 @@ static int dh_pkey_copy(EVP_PKEY *to, EVP_PKEY *from)
     int ret;
 
     if (dh != NULL) {
-        dupkey = dh_dup(dh);
+        dupkey = ossl_dh_dup(dh);
         if (dupkey == NULL)
             return 0;
     }
diff --git a/crypto/dh/dh_backend.c b/crypto/dh/dh_backend.c
index 97f5271a5a..aebb38d1c9 100644
--- a/crypto/dh/dh_backend.c
+++ b/crypto/dh/dh_backend.c
@@ -17,6 +17,7 @@
 #include <openssl/core_names.h>
 #include "internal/param_build_set.h"
 #include "crypto/dh.h"
+#include "dh_local.h"
 
 /*
  * The intention with the "backend" source file is to offer backend functions
@@ -117,6 +118,49 @@ int ossl_dh_key_todata(DH *dh, OSSL_PARAM_BLD *bld, OSSL_PARAM params[])
     return 1;
 }
 
+static ossl_inline int dh_bn_dup_check(BIGNUM **out, const BIGNUM *f)
+{
+    if (f != NULL && (*out = BN_dup(f)) == NULL)
+        return 0;
+    return 1;
+}
+
+DH *ossl_dh_dup(const DH *dh)
+{
+    DH *dupkey = NULL;
+
+#ifndef FIPS_MODULE
+    /* Do not try to duplicate foreign DH keys */
+    if (ossl_dh_get_method(dh) != DH_OpenSSL())
+        return NULL;
+#endif
+
+    if ((dupkey = ossl_dh_new_ex(dh->libctx)) == NULL)
+        return NULL;
+
+    dupkey->length = DH_get_length(dh);
+    if (!ossl_ffc_params_copy(&dupkey->params, &dh->params))
+        goto err;
+
+    dupkey->flags = dh->flags;
+
+    if (!dh_bn_dup_check(&dupkey->pub_key, dh->pub_key))
+        goto err;
+    if (!dh_bn_dup_check(&dupkey->priv_key, dh->priv_key))
+        goto err;
+
+#ifndef FIPS_MODULE
+    if (!CRYPTO_dup_ex_data(CRYPTO_EX_INDEX_DH,
+                            &dupkey->ex_data, &dh->ex_data))
+        goto err;
+#endif
+
+    return dupkey;
+
+ err:
+    DH_free(dupkey);
+    return NULL;
+}
 #ifndef FIPS_MODULE
 DH *ossl_dh_key_from_pkcs8(const PKCS8_PRIV_KEY_INFO *p8inf,
                            OSSL_LIB_CTX *libctx, const char *propq)
diff --git a/crypto/dh/dh_lib.c b/crypto/dh/dh_lib.c
index f5e0f893c1..92767a94c2 100644
--- a/crypto/dh/dh_lib.c
+++ b/crypto/dh/dh_lib.c
@@ -325,3 +325,5 @@ int ossl_dh_get0_nid(const DH *dh)
 {
     return dh->params.nid;
 }
+
+