EVP: Implement support for key downgrading in backends

[oweals/openssl.git] / crypto / dh / dh_ameth.c

diff --git a/crypto/dh/dh_ameth.c b/crypto/dh/dh_ameth.c
index bee414abf7e14ea5c6e876c3487d0b30c6f5cd19..d0eaceccb4fa032f16ed715c883e6df57941c16e 100644 (file)
--- a/crypto/dh/dh_ameth.c
+++ b/crypto/dh/dh_ameth.c
@@ -7,6 +7,12 @@
  * https://www.openssl.org/source/license.html
  */
 
+/*
+ * DH low level APIs are deprecated for public use, but still ok for
+ * internal use.
+ */
+#include "internal/deprecated.h"
+
 #include <stdio.h>
 #include "internal/cryptlib.h"
 #include <openssl/x509.h>
@@ -14,10 +20,12 @@
 #include "dh_local.h"
 #include <openssl/bn.h>
 #include "crypto/asn1.h"
+#include "crypto/dh.h"
 #include "crypto/evp.h"
 #include <openssl/cms.h>
 #include <openssl/core_names.h>
 #include "internal/param_build.h"
+#include "internal/ffc.h"
 
 /*
  * i2d/d2i like DH parameter functions which use the appropriate routine for
@@ -491,8 +499,16 @@ static int dh_pkey_export_to(const EVP_PKEY *from, void *to_keydata,
     const BIGNUM *pub_key = DH_get0_pub_key(dh);
     const BIGNUM *priv_key = DH_get0_priv_key(dh);
     OSSL_PARAM *params;
+    int selection = 0;
     int rv;
 
+    /*
+     * If the DH method is foreign, then we can't be sure of anything, and
+     * can therefore not export or pretend to export.
+     */
+    if (dh_get_method(dh) != DH_OpenSSL())
+        return 0;
+
     if (p == NULL || g == NULL)
         return 0;
 
@@ -504,27 +520,49 @@ static int dh_pkey_export_to(const EVP_PKEY *from, void *to_keydata,
         if (!ossl_param_bld_push_BN(&tmpl, OSSL_PKEY_PARAM_FFC_Q, q))
             return 0;
     }
-    /* A key must at least have a public part. */
-    if (!ossl_param_bld_push_BN(&tmpl, OSSL_PKEY_PARAM_PUB_KEY, pub_key))
-        return 0;
+    selection |= OSSL_KEYMGMT_SELECT_DOMAIN_PARAMETERS;
+    if (pub_key != NULL) {
+        if (!ossl_param_bld_push_BN(&tmpl, OSSL_PKEY_PARAM_PUB_KEY, pub_key))
+            return 0;
+        selection |= OSSL_KEYMGMT_SELECT_PUBLIC_KEY;
+    }
     if (priv_key != NULL) {
         if (!ossl_param_bld_push_BN(&tmpl, OSSL_PKEY_PARAM_PRIV_KEY,
                                     priv_key))
             return 0;
+        selection |= OSSL_KEYMGMT_SELECT_PRIVATE_KEY;
     }
 
     if ((params = ossl_param_bld_to_param(&tmpl)) == NULL)
         return 0;
 
     /* We export, the provider imports */
-    rv = evp_keymgmt_import(to_keymgmt, to_keydata, OSSL_KEYMGMT_SELECT_ALL,
-                            params);
+    rv = evp_keymgmt_import(to_keymgmt, to_keydata, selection, params);
 
     ossl_param_bld_free(params);
 
     return rv;
 }
 
+static int dh_pkey_import_from(const OSSL_PARAM params[], void *key)
+{
+    EVP_PKEY *pkey = key;
+    DH *dh = DH_new();
+
+    if (dh == NULL) {
+        ERR_raise(ERR_LIB_DH, ERR_R_MALLOC_FAILURE);
+        return 0;
+    }
+
+    if (!ffc_fromdata(dh_get0_params(dh), params)
+        || !dh_key_fromdata(dh, params)
+        || !EVP_PKEY_assign_DH(pkey, dh)) {
+        DH_free(dh);
+        return 0;
+    }
+    return 1;
+}
+
 const EVP_PKEY_ASN1_METHOD dh_asn1_meth = {
     EVP_PKEY_DH,
     EVP_PKEY_DH,
@@ -567,6 +605,7 @@ const EVP_PKEY_ASN1_METHOD dh_asn1_meth = {
 
     dh_pkey_dirty_cnt,
     dh_pkey_export_to,
+    dh_pkey_import_from,
 };
 
 const EVP_PKEY_ASN1_METHOD dhx_asn1_meth = {