Revise EVP_PKEY param handling

We add new functions for getting parameters and discovering the gettable
and settable parameters. We also make EVP_PKEY_CTX_get_signature_md() a
function and implement it in terms of the new functions.

This enables applications to discover the set of parameters that are
supported for a given algorithm implementation.

Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/9753)

1 files changed, 114 insertions, 0 deletions

diff --git a/test/evp_extra_test.c b/test/evp_extra_test.c
index 1ad62d2f79..7b7c632dd1 100644
--- a/test/evp_extra_test.c
+++ b/test/evp_extra_test.c
@@ -19,6 +19,8 @@
 #include <openssl/pem.h>
 #include <openssl/kdf.h>
 #include <openssl/provider.h>
+#include <openssl/core_names.h>
+#include <openssl/dsa.h>
 #include "testutil.h"
 #include "internal/nelem.h"
 #include "internal/evp_int.h"
@@ -1393,6 +1395,117 @@ static int test_EVP_CIPHER_fetch(int tst)
     return ret;
 }
 
+/* Test getting and setting parameters on an EVP_PKEY_CTX */
+static int test_EVP_PKEY_CTX_get_set_params(void)
+{
+    EVP_PKEY_CTX *ctx = NULL;
+    EVP_SIGNATURE *dsaimpl = NULL;
+    const OSSL_PARAM *params;
+    OSSL_PARAM ourparams[2], *param = ourparams;
+    DSA *dsa = NULL;
+    BIGNUM *p = NULL, *q = NULL, *g = NULL;
+    EVP_PKEY *pkey = NULL;
+    int ret = 0;
+    const EVP_MD *md;
+    size_t mdsize = SHA512_DIGEST_LENGTH;
+
+    /*
+     * Setup the parameters for our DSA object. For our purposes they don't have
+     * to actually be *valid* parameters. We just need to set something. We
+     * don't even need a pub_key/priv_key.
+     */
+    dsa = DSA_new();
+    p = BN_new();
+    q = BN_new();
+    g = BN_new();
+    if (!TEST_ptr(dsa)
+            || !TEST_ptr(p)
+            || !TEST_ptr(q)
+            || !TEST_ptr(g)
+            || !DSA_set0_pqg(dsa, p, q, g))
+        goto err;
+    p = q = g = NULL;
+
+    pkey = EVP_PKEY_new();
+    if (!TEST_ptr(pkey)
+            || !TEST_true(EVP_PKEY_assign_DSA(pkey, dsa)))
+        goto err;
+
+    dsa = NULL;
+
+    /* Initialise a sign operation */
+    ctx = EVP_PKEY_CTX_new(pkey, NULL);
+    dsaimpl = EVP_SIGNATURE_fetch(NULL, "DSA", NULL);
+    if (!TEST_ptr(ctx)
+            || !TEST_ptr(dsaimpl)
+            || !TEST_int_gt(EVP_PKEY_sign_init_ex(ctx, dsaimpl), 0))
+        goto err;
+
+    /*
+     * We should be able to query the parameters now. The default DSA
+     * implementation supports exactly one parameter - so we expect to see that
+     * returned and no more.
+     */
+    params = EVP_PKEY_CTX_settable_params(ctx);
+    if (!TEST_ptr(params)
+            || !TEST_int_eq(strcmp(params[0].key,
+                            OSSL_SIGNATURE_PARAM_DIGEST_SIZE), 0)
+            || !TEST_int_eq(strcmp(params[1].key, OSSL_SIGNATURE_PARAM_DIGEST),
+                            0)
+               /* The final key should be NULL */
+            || !TEST_ptr_null(params[2].key))
+        goto err;
+
+    /* Gettable params are the same as the settable ones */
+    params = EVP_PKEY_CTX_gettable_params(ctx);
+    if (!TEST_ptr(params)
+            || !TEST_int_eq(strcmp(params[0].key,
+                            OSSL_SIGNATURE_PARAM_DIGEST_SIZE), 0)
+            || !TEST_int_eq(strcmp(params[1].key, OSSL_SIGNATURE_PARAM_DIGEST),
+                            0)
+               /* The final key should be NULL */
+            || !TEST_ptr_null(params[2].key))
+        goto err;
+
+    /*
+     * Test getting and setting params via EVP_PKEY_CTX_set_params() and
+     * EVP_PKEY_CTX_get_params()
+     */
+    *param++ = OSSL_PARAM_construct_size_t(OSSL_SIGNATURE_PARAM_DIGEST_SIZE,
+                                           &mdsize);
+    *param++ = OSSL_PARAM_construct_end();
+
+    if (!TEST_true(EVP_PKEY_CTX_set_params(ctx, ourparams)))
+        goto err;
+
+    mdsize = 0;
+    if (!TEST_true(EVP_PKEY_CTX_get_params(ctx, ourparams))
+            || !TEST_size_t_eq(mdsize, SHA512_DIGEST_LENGTH))
+        goto err;
+
+    /*
+     * Test the TEST_PKEY_CTX_set_signature_md() and
+     * TEST_PKEY_CTX_get_signature_md() functions
+     */
+    if (!TEST_int_gt(EVP_PKEY_CTX_set_signature_md(ctx, EVP_sha256()), 0)
+            || !TEST_int_gt(EVP_PKEY_CTX_get_signature_md(ctx, &md), 0)
+            || !TEST_ptr_eq(md, EVP_sha256()))
+        goto err;
+
+    ret = 1;
+
+ err:
+    EVP_PKEY_CTX_free(ctx);
+    EVP_SIGNATURE_free(dsaimpl);
+    EVP_PKEY_free(pkey);
+    DSA_free(dsa);
+    BN_free(p);
+    BN_free(q);
+    BN_free(g);
+
+    return ret;
+}
+
 int setup_tests(void)
 {
     ADD_TEST(test_EVP_DigestSignInit);
@@ -1429,5 +1542,6 @@ int setup_tests(void)
     ADD_ALL_TESTS(test_EVP_MD_fetch, 5);
     ADD_ALL_TESTS(test_EVP_CIPHER_fetch, 5);
 #endif
+    ADD_TEST(test_EVP_PKEY_CTX_get_set_params);
     return 1;
 }