rsa: add support of padding pss

We add the support of the padding pss for rsa signature.
This new padding is often recommended instead of pkcs-1.5.

Signed-off-by: Philippe Reynes <philippe.reynes@softathome.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/lib/rsa/rsa-sign.c b/lib/rsa/rsa-sign.c
index 6aa0e2a..fb5e07b 100644
--- a/lib/rsa/rsa-sign.c
+++ b/lib/rsa/rsa-sign.c
@@ -438,6 +438,16 @@
 		goto err_sign;
 	}
 
+#ifdef CONFIG_FIT_ENABLE_RSASSA_PSS_SUPPORT
+	if (padding_algo && !strcmp(padding_algo->name, "pss")) {
+		if (EVP_PKEY_CTX_set_rsa_padding(ckey,
+						 RSA_PKCS1_PSS_PADDING) <= 0) {
+			ret = rsa_err("Signer padding setup failed");
+			goto err_sign;
+		}
+	}
+#endif /* CONFIG_FIT_ENABLE_RSASSA_PSS_SUPPORT */
+
 	for (i = 0; i < region_count; i++) {
 		if (!EVP_DigestSignUpdate(context, region[i].data,
 					  region[i].size)) {