Enable OpenSSL's SP800-108 5.1 implementation

Starting in 3.0, OpenSSL implements part of SP800-108, which we use as
part of KDF for the aes2 enctypes.

src/lib/crypto/krb/derive.c

@@ -27,6 +27,12 @@
 
 #include "crypto_int.h"
 
+#ifdef HAVE_OPENSSL_KDFS
+#include <openssl/core_names.h>
+#include <openssl/evp.h>
+#include <openssl/kdf.h>
+#endif
+
 static krb5_key
 find_cached_dkey(struct derived_key *list, const krb5_data *constant)
 {
@@ -204,6 +210,64 @@ derive_random_sp800_108_feedback_cmac(const struct krb5_enc_provider *enc,
     return ret;
 }
 
+#ifdef HAVE_OPENSSL_KDFS
+krb5_error_code
+openssl_kbdkf_counter_hmac(const struct krb5_hash_provider *hash,
+                          krb5_key inkey, krb5_data *outrnd,
+                          const krb5_data *label, const krb5_data *context)
+{
+    krb5_error_code ret = KRB5_CRYPTO_INTERNAL;
+    EVP_KDF *kdf = NULL;
+    EVP_KDF_CTX *kctx = NULL;
+    OSSL_PARAM params[6];
+    size_t i = 0;
+    char *digest;
+
+    if (!strcmp(hash->hash_name, "SHA1"))
+        digest = "SHA1";
+    else if (!strcmp(hash->hash_name, "SHA-256"))
+        digest = "SHA256";
+    else if (!strcmp(hash->hash_name, "SHA-384"))
+        digest = "SHA384";
+    else
+        goto done;
+
+    kdf = EVP_KDF_fetch(NULL, "KBKDF", NULL);
+    if (!kdf)
+        goto done;
+
+    kctx = EVP_KDF_CTX_new(kdf);
+    if (!kctx)
+        goto done;
+
+    params[i++] = OSSL_PARAM_construct_utf8_string(OSSL_KDF_PARAM_DIGEST,
+                                                   digest, 0);
+    params[i++] = OSSL_PARAM_construct_utf8_string(OSSL_KDF_PARAM_MAC,
+                                                   "HMAC", 0);
+    params[i++] = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_KEY,
+                                                    inkey->keyblock.contents,
+                                                    inkey->keyblock.length);
+    params[i++] = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_INFO,
+                                                    context->data,
+                                                    context->length);
+    params[i++] = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_SALT,
+                                                    label->data,
+                                                    label->length);
+    params[i] = OSSL_PARAM_construct_end();
+    if (EVP_KDF_CTX_set_params(kctx, params) <= 0) {
+        goto done;
+    } else if (EVP_KDF_derive(kctx, (unsigned char *)outrnd->data,
+                              outrnd->length) <= 0) {
+        goto done;
+    }
+
+    ret = 0;
+done:
+    EVP_KDF_free(kdf);
+    EVP_KDF_CTX_free(kctx);
+    return ret;
+}
+#else
 /*
  * NIST SP800-108 KDF in counter mode (section 5.1).
  * Parameters:
@@ -214,9 +278,10 @@ derive_random_sp800_108_feedback_cmac(const struct krb5_enc_provider *enc,
  * There are no uses requiring more than a single PRF invocation.
  */
 krb5_error_code
-k5_sp800_108_counter_hmac(const struct krb5_hash_provider *hash,
-                          krb5_key inkey, krb5_data *outrnd,
-                          const krb5_data *label, const krb5_data *context)
+builtin_sp800_108_counter_hmac(const struct krb5_hash_provider *hash,
+                               krb5_key inkey, krb5_data *outrnd,
+                               const krb5_data *label,
+                               const krb5_data *context)
 {
     krb5_crypto_iov iov[5];
     krb5_error_code ret;
@@ -255,6 +320,20 @@ k5_sp800_108_counter_hmac(const struct krb5_hash_provider *hash,
     zapfree(prf.data, prf.length);
     return ret;
 }
+#endif
+krb5_error_code
+k5_sp800_108_counter_hmac(const struct krb5_hash_provider *hash,
+                          krb5_key inkey, krb5_data *outrnd,
+                          const krb5_data *label, const krb5_data *context)
+{
+#ifdef HAVE_OPENSSL_KDFS
+    return openssl_kbdkf_counter_hmac(hash, inkey, outrnd, label, context);
+#else
+    return builtin_sp800_108_counter_hmac(hash, inkey, outrnd, label,
+                                          context);
+#endif
+}
+
 
 krb5_error_code
 krb5int_derive_random(const struct krb5_enc_provider *enc,