Use X509_ALGOR_get0() in ecdh_cms_set_shared_info()

This makes things slightly less gross since it involves less reaching
into nested ASN.1 structures.  But don't get the idea that this means
the code is now clean.

ok jsing

diff --git a/lib/libcrypto/ec/ec_ameth.c b/lib/libcrypto/ec/ec_ameth.c
index 883832f..313d218 100644 (file)
--- a/lib/libcrypto/ec/ec_ameth.c
+++ b/lib/libcrypto/ec/ec_ameth.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ec_ameth.c,v 1.65 2024/04/18 11:51:53 tb Exp $ */
+/* $OpenBSD: ec_ameth.c,v 1.66 2024/04/18 11:53:40 tb Exp $ */
 /* Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL
  * project 2006.
  */
@@ -820,6 +820,10 @@ static int
 ecdh_cms_set_shared_info(EVP_PKEY_CTX *pctx, CMS_RecipientInfo *ri)
 {
        X509_ALGOR *alg, *kekalg = NULL;
+       const ASN1_OBJECT *obj;
+       int nid;
+       const void *parameter;
+       int parameter_type;
        ASN1_OCTET_STRING *ukm;
        const unsigned char *p;
        unsigned char *der = NULL;
@@ -831,16 +835,20 @@ ecdh_cms_set_shared_info(EVP_PKEY_CTX *pctx, CMS_RecipientInfo *ri)
        if (!CMS_RecipientInfo_kari_get0_alg(ri, &alg, &ukm))
                goto err;
 
-       if (!ecdh_cms_set_kdf_param(pctx, OBJ_obj2nid(alg->algorithm))) {
+       X509_ALGOR_get0(&obj, &parameter_type, &parameter, alg);
+
+       if ((nid = OBJ_obj2nid(obj)) == NID_undef)
+               goto err;
+       if (!ecdh_cms_set_kdf_param(pctx, nid)) {
                ECerror(EC_R_KDF_PARAMETER_ERROR);
                goto err;
        }
 
-       if (alg->parameter->type != V_ASN1_SEQUENCE)
+       if (parameter_type != V_ASN1_SEQUENCE)
                goto err;
-
-       p = alg->parameter->value.sequence->data;
-       plen = alg->parameter->value.sequence->length;
+       if ((p = ASN1_STRING_get0_data(parameter)) == NULL)
+               goto err;
+       plen = ASN1_STRING_length(parameter);
        if ((kekalg = d2i_X509_ALGOR(NULL, &p, plen)) == NULL)
                goto err;
        if ((kekctx = CMS_RecipientInfo_kari_get0_ctx(ri)) == NULL)