Redesign the KEYMGMT libcrypto <-> provider interface - the basics

The KEYMGMT libcrypto <-> provider interface currently makes a few
assumptions:

1.  provider side domain parameters and key data isn't mutable. In
    other words, as soon as a key has been created in any (loaded,
    imported data, ...), it's set in stone.
2.  provider side domain parameters can be strictly separated from the
    key data.

This does work for the most part, but there are places where that's a
bit too rigid for the functionality that the EVP_PKEY API delivers.
Key data needs to be mutable to allow the flexibility that functions
like EVP_PKEY_copy_parameters promise, as well as to provide the
combinations of data that an EVP_PKEY is generally assumed to be able
to hold:

- domain parameters only
- public key only
- public key + private key
- domain parameters + public key
- domain parameters + public key + private key

To remedy all this, we:

1.  let go of the distinction between domain parameters and key
    material proper in the libcrypto <-> provider interface.

    As a consequence, functions that still need it gain a selection
    argument, which is a set of bits that indicate what parts of the
    key object are to be considered in a specific call.  This allows
    a reduction of very similar functions into one.

2.  Rework the libcrypto <-> provider interface so provider side key
    objects are created and destructed with a separate function, and
    get their data filled and extracted in through import and export.

(future work will see other key object constructors and other
functions to fill them with data)

Fixes #10979

squash! Redesign the KEYMGMT libcrypto <-> provider interface - the basics

Remedy 1 needs a rewrite:

Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Shane Lontis <shane.lontis@oracle.com>
Reviewed-by: Paul Dale <paul.dale@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/11006)

2 files changed, 44 insertions, 48 deletions

diff --git a/crypto/dsa/dsa_ameth.c b/crypto/dsa/dsa_ameth.c
index 510b204b2d..9d1b89717c 100644
--- a/crypto/dsa/dsa_ameth.c
+++ b/crypto/dsa/dsa_ameth.c
@@ -511,48 +511,44 @@ static size_t dsa_pkey_dirty_cnt(const EVP_PKEY *pkey)
     return pkey->pkey.dsa->dirty_cnt;
 }
 
-static void *dsa_pkey_export_to(const EVP_PKEY *pk, EVP_KEYMGMT *keymgmt,
-                                int want_domainparams)
+static int dsa_pkey_export_to(const EVP_PKEY *from, void *to_keydata,
+                              EVP_KEYMGMT *to_keymgmt)
 {
-    DSA *dsa = pk->pkey.dsa;
+    DSA *dsa = from->pkey.dsa;
     OSSL_PARAM_BLD tmpl;
     const BIGNUM *p = DSA_get0_p(dsa), *g = DSA_get0_g(dsa);
     const BIGNUM *q = DSA_get0_q(dsa), *pub_key = DSA_get0_pub_key(dsa);
     const BIGNUM *priv_key = DSA_get0_priv_key(dsa);
     OSSL_PARAM *params;
-    void *provdata = NULL;
+    int rv;
 
     if (p == NULL || q == NULL || g == NULL)
-        return NULL;
+        return 0;
 
     ossl_param_bld_init(&tmpl);
     if (!ossl_param_bld_push_BN(&tmpl, OSSL_PKEY_PARAM_FFC_P, p)
         || !ossl_param_bld_push_BN(&tmpl, OSSL_PKEY_PARAM_FFC_Q, q)
         || !ossl_param_bld_push_BN(&tmpl, OSSL_PKEY_PARAM_FFC_G, g))
-        return NULL;
-
-    if (!want_domainparams) {
-        /* A key must at least have a public part. */
-        if (!ossl_param_bld_push_BN(&tmpl, OSSL_PKEY_PARAM_DSA_PUB_KEY,
-                                    pub_key))
-            return NULL;
-
-        if (priv_key != NULL) {
-            if (!ossl_param_bld_push_BN(&tmpl, OSSL_PKEY_PARAM_DSA_PRIV_KEY,
-                                        priv_key))
-                return NULL;
-        }
+        return 0;
+    if (!ossl_param_bld_push_BN(&tmpl, OSSL_PKEY_PARAM_DSA_PUB_KEY,
+                                pub_key))
+        return 0;
+    if (priv_key != NULL) {
+        if (!ossl_param_bld_push_BN(&tmpl, OSSL_PKEY_PARAM_DSA_PRIV_KEY,
+                                    priv_key))
+            return 0;
     }
 
-    params = ossl_param_bld_to_param(&tmpl);
+    if ((params = ossl_param_bld_to_param(&tmpl)) == NULL)
+        return 0;
 
     /* We export, the provider imports */
-    provdata = want_domainparams
-        ? evp_keymgmt_importdomparams(keymgmt, params)
-        : evp_keymgmt_importkey(keymgmt, params);
+    rv = evp_keymgmt_import(to_keymgmt, to_keydata, OSSL_KEYMGMT_SELECT_ALL,
+                            params);
 
     ossl_param_bld_free(params);
-    return provdata;
+
+    return rv;
 }
 
 /* NB these are sorted in pkey_id order, lowest first */
diff --git a/crypto/dsa/dsa_lib.c b/crypto/dsa/dsa_lib.c
index 469746e65d..334ee747dd 100644
--- a/crypto/dsa/dsa_lib.c
+++ b/crypto/dsa/dsa_lib.c
@@ -75,31 +75,6 @@ DH *DSA_dup_DH(const DSA *r)
 }
 # endif /*  OPENSSL_NO_DH */
 
-const BIGNUM *DSA_get0_p(const DSA *d)
-{
-    return d->params.p;
-}
-
-const BIGNUM *DSA_get0_q(const DSA *d)
-{
-    return d->params.q;
-}
-
-const BIGNUM *DSA_get0_g(const DSA *d)
-{
-    return d->params.g;
-}
-
-const BIGNUM *DSA_get0_pub_key(const DSA *d)
-{
-    return d->pub_key;
-}
-
-const BIGNUM *DSA_get0_priv_key(const DSA *d)
-{
-    return d->priv_key;
-}
-
 void DSA_clear_flags(DSA *d, int flags)
 {
     d->flags &= ~flags;
@@ -278,6 +253,31 @@ int DSA_set0_pqg(DSA *d, BIGNUM *p, BIGNUM *q, BIGNUM *g)
     return 1;
 }
 
+const BIGNUM *DSA_get0_p(const DSA *d)
+{
+    return d->params.p;
+}
+
+const BIGNUM *DSA_get0_q(const DSA *d)
+{
+    return d->params.q;
+}
+
+const BIGNUM *DSA_get0_g(const DSA *d)
+{
+    return d->params.g;
+}
+
+const BIGNUM *DSA_get0_pub_key(const DSA *d)
+{
+    return d->pub_key;
+}
+
+const BIGNUM *DSA_get0_priv_key(const DSA *d)
+{
+    return d->priv_key;
+}
+
 void DSA_get0_key(const DSA *d,
                   const BIGNUM **pub_key, const BIGNUM **priv_key)
 {