hmac: stop using secure memory for the HMAC key

Secure memory is design for long term storage of private material.
HMAC keys are not this.

Secure memory use was introduced in July 2020 by commit
3fddbb264e87a8cef2903cbd7b02b8e1a39a2a99.

Fixes #28346

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Dmitry Belyavskiy <beldmit@gmail.com>
(Merged from https://github.com/openssl/openssl/pull/28412)

(cherry picked from commit 8e3c76085fd163e2d0c4d54ac8105407c54daff6)

diff --git a/providers/implementations/macs/hmac_prov.c b/providers/implementations/macs/hmac_prov.c
index a1f3c2db84d65b9999c63cba54ee9cc6b21454e1..a022e7f11cf2827add06e8f23cd7c6ec1b9b2c1b 100644 (file)
--- a/providers/implementations/macs/hmac_prov.c
+++ b/providers/implementations/macs/hmac_prov.c
@@ -85,7 +85,7 @@ static void hmac_free(void *vmacctx)
     if (macctx != NULL) {
         HMAC_CTX_free(macctx->ctx);
         ossl_prov_digest_reset(&macctx->digest);
-        OPENSSL_secure_clear_free(macctx->key, macctx->keylen);
+        OPENSSL_clear_free(macctx->key, macctx->keylen);
         OPENSSL_free(macctx);
     }
 }
@@ -114,13 +114,13 @@ static void *hmac_dup(void *vsrc)
         return NULL;
     }
     if (src->key != NULL) {
-        /* There is no "secure" OPENSSL_memdup */
-        dst->key = OPENSSL_secure_malloc(src->keylen > 0 ? src->keylen : 1);
+        dst->key = OPENSSL_malloc(src->keylen > 0 ? src->keylen : 1);
         if (dst->key == NULL) {
             hmac_free(dst);
             return 0;
         }
-        memcpy(dst->key, src->key, src->keylen);
+        if (src->keylen > 0)
+            memcpy(dst->key, src->key, src->keylen);
     }
     return dst;
 }
@@ -145,12 +145,14 @@ static int hmac_setkey(struct hmac_data_st *macctx,
     const EVP_MD *digest;
 
     if (macctx->key != NULL)
-        OPENSSL_secure_clear_free(macctx->key, macctx->keylen);
+        OPENSSL_clear_free(macctx->key, macctx->keylen);
     /* Keep a copy of the key in case we need it for TLS HMAC */
-    macctx->key = OPENSSL_secure_malloc(keylen > 0 ? keylen : 1);
+    macctx->key = OPENSSL_malloc(keylen > 0 ? keylen : 1);
     if (macctx->key == NULL)
         return 0;
-    memcpy(macctx->key, key, keylen);
+
+    if (keylen > 0)
+        memcpy(macctx->key, key, keylen);
     macctx->keylen = keylen;
 
     digest = ossl_prov_digest_md(&macctx->digest);