crypto: use X509_ALGOR accessors instead of reaching into X509_ALGOR

While the struct is still public in OpenSSL, there is a (somewhat
inconvenient) accessor. Use it to remain compatible if it becomes opaque
in the future.

PR-URL: #50057
Reviewed-By: Ben Noordhuis <[email protected]>
Reviewed-By: Tobias Nießen <[email protected]>

Author: davidben

src/crypto/crypto_rsa.cc

@@ -577,7 +577,9 @@ Maybe<bool> GetRsaKeyDetail(
       int64_t salt_length = 20;
 
       if (params->hashAlgorithm != nullptr) {
-        hash_nid = OBJ_obj2nid(params->hashAlgorithm->algorithm);
+        const ASN1_OBJECT* hash_obj;
+        X509_ALGOR_get0(&hash_obj, nullptr, nullptr, params->hashAlgorithm);
+        hash_nid = OBJ_obj2nid(hash_obj);
       }
 
       if (target
@@ -590,9 +592,13 @@ Maybe<bool> GetRsaKeyDetail(
       }
 
       if (params->maskGenAlgorithm != nullptr) {
-        mgf_nid = OBJ_obj2nid(params->maskGenAlgorithm->algorithm);
+        const ASN1_OBJECT* mgf_obj;
+        X509_ALGOR_get0(&mgf_obj, nullptr, nullptr, params->maskGenAlgorithm);
+        mgf_nid = OBJ_obj2nid(mgf_obj);
         if (mgf_nid == NID_mgf1) {
-          mgf1_hash_nid = OBJ_obj2nid(params->maskHash->algorithm);
+          const ASN1_OBJECT* mgf1_hash_obj;
+          X509_ALGOR_get0(&mgf1_hash_obj, nullptr, nullptr, params->maskHash);
+          mgf1_hash_nid = OBJ_obj2nid(mgf1_hash_obj);
         }
       }