DH: make the private key length importable / exportable

The DH private key length, which is an optional parameter, wasn't
properly imported / exported between legacy and provider side
implementations.

Reviewed-by: Paul Dale <paul.dale@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/13166)

3 files changed, 73 insertions, 20 deletions

diff --git a/crypto/dh/dh_ameth.c b/crypto/dh/dh_ameth.c
index 69b166362a..49e65e4d6c 100644
--- a/crypto/dh/dh_ameth.c
+++ b/crypto/dh/dh_ameth.c
@@ -485,6 +485,7 @@ static int dh_pkey_export_to(const EVP_PKEY *from, void *to_keydata,
     DH *dh = from->pkey.dh;
     OSSL_PARAM_BLD *tmpl;
     const BIGNUM *p = DH_get0_p(dh), *g = DH_get0_g(dh), *q = DH_get0_q(dh);
+    long l = DH_get_length(dh);
     const BIGNUM *pub_key = DH_get0_pub_key(dh);
     const BIGNUM *priv_key = DH_get0_priv_key(dh);
     OSSL_PARAM *params = NULL;
@@ -512,6 +513,11 @@ static int dh_pkey_export_to(const EVP_PKEY *from, void *to_keydata,
             goto err;
     }
     selection |= OSSL_KEYMGMT_SELECT_DOMAIN_PARAMETERS;
+    if (l > 0) {
+        if (!OSSL_PARAM_BLD_push_long(tmpl, OSSL_PKEY_PARAM_DH_PRIV_LEN, l))
+            goto err;
+        selection |= OSSL_KEYMGMT_SELECT_OTHER_PARAMETERS;
+    }
     if (pub_key != NULL) {
         if (!OSSL_PARAM_BLD_push_BN(tmpl, OSSL_PKEY_PARAM_PUB_KEY, pub_key))
             goto err;
@@ -550,7 +556,7 @@ static int dh_pkey_import_from_type(const OSSL_PARAM params[], void *vpctx,
     DH_clear_flags(dh, DH_FLAG_TYPE_MASK);
     DH_set_flags(dh, type == EVP_PKEY_DH ? DH_FLAG_TYPE_DH : DH_FLAG_TYPE_DHX);
 
-    if (!dh_ffc_params_fromdata(dh, params)
+    if (!dh_params_fromdata(dh, params)
         || !dh_key_fromdata(dh, params)
         || !EVP_PKEY_assign(pkey, type, dh)) {
         DH_free(dh);
diff --git a/crypto/dh/dh_backend.c b/crypto/dh/dh_backend.c
index 704f6efac1..1ce29e652d 100644
--- a/crypto/dh/dh_backend.c
+++ b/crypto/dh/dh_backend.c
@@ -8,6 +8,7 @@
  */
 
 #include <openssl/core_names.h>
+#include "internal/param_build_set.h"
 #include "crypto/dh.h"
 
 /*
@@ -16,6 +17,41 @@
  * implementations alike.
  */
 
+static int dh_ffc_params_fromdata(DH *dh, const OSSL_PARAM params[])
+{
+    int ret;
+    FFC_PARAMS *ffc;
+
+    if (dh == NULL)
+        return 0;
+    ffc = dh_get0_params(dh);
+    if (ffc == NULL)
+        return 0;
+
+    ret = ossl_ffc_params_fromdata(ffc, params);
+    if (ret)
+        dh_cache_named_group(dh); /* This increments dh->dirt_cnt */
+    return ret;
+}
+
+int dh_params_fromdata(DH *dh, const OSSL_PARAM params[])
+{
+    const OSSL_PARAM *param_priv_len;
+    long priv_len;
+
+    if (!dh_ffc_params_fromdata(dh, params))
+        return 0;
+
+    param_priv_len =
+        OSSL_PARAM_locate_const(params, OSSL_PKEY_PARAM_DH_PRIV_LEN);
+    if (param_priv_len != NULL
+        && (!OSSL_PARAM_get_long(param_priv_len, &priv_len)
+            || !DH_set_length(dh, priv_len)))
+        return 0;
+
+    return 1;
+}
+
 int dh_key_fromdata(DH *dh, const OSSL_PARAM params[])
 {
     const OSSL_PARAM *param_priv_key, *param_pub_key;
@@ -52,3 +88,33 @@ int dh_key_fromdata(DH *dh, const OSSL_PARAM params[])
     BN_free(pub_key);
     return 0;
 }
+
+int dh_params_todata(DH *dh, OSSL_PARAM_BLD *bld, OSSL_PARAM params[])
+{
+    long l = DH_get_length(dh);
+
+    if (!ossl_ffc_params_todata(dh_get0_params(dh), bld, params))
+        return 0;
+    if (l > 0
+        && !ossl_param_build_set_long(bld, params, OSSL_PKEY_PARAM_DH_PRIV_LEN, l))
+        return 0;
+    return 1;
+}
+
+int dh_key_todata(DH *dh, OSSL_PARAM_BLD *bld, OSSL_PARAM params[])
+{
+    const BIGNUM *priv = NULL, *pub = NULL;
+
+    if (dh == NULL)
+        return 0;
+
+    DH_get0_key(dh, &pub, &priv);
+    if (priv != NULL
+        && !ossl_param_build_set_bn(bld, params, OSSL_PKEY_PARAM_PRIV_KEY, priv))
+        return 0;
+    if (pub != NULL
+        && !ossl_param_build_set_bn(bld, params, OSSL_PKEY_PARAM_PUB_KEY, pub))
+        return 0;
+
+    return 1;
+}
diff --git a/crypto/dh/dh_lib.c b/crypto/dh/dh_lib.c
index 94978a2cb2..e6eba34ac9 100644
--- a/crypto/dh/dh_lib.c
+++ b/crypto/dh/dh_lib.c
@@ -325,22 +325,3 @@ int dh_get0_nid(const DH *dh)
 {
     return dh->params.nid;
 }
-
-int dh_ffc_params_fromdata(DH *dh, const OSSL_PARAM params[])
-{
-    int ret;
-    FFC_PARAMS *ffc;
-
-    if (dh == NULL)
-        return 0;
-    ffc = dh_get0_params(dh);
-    if (ffc == NULL)
-        return 0;
-
-    ret = ossl_ffc_params_fromdata(ffc, params);
-    if (ret) {
-        dh_cache_named_group(dh);
-        dh->dirty_cnt++;
-    }
-    return ret;
-}