Report MACAddress is read-only for a D-Bus Not Allowed response

The BMC Manager MACAddress ethernet property is a Read/Write property
in the Redfish spec. There are OpenBMC users that configure the
property to be Read Only. The phosphor-network build includes a
'persist-mac' configuration switch which controls MAC address
assignment. An attempt to set a R/O MACAddress causes D-Bus to return
an error. The exact error is available in a sdbus message.

The EthernetInterface XML indicates this is acceptable behavior:
"If an assignable MAC address is not supported, this value is a
read-only alias of the PermanentMACAddress."

As this condition is considered proper behavior it is incorrect to
return an internalError(). It is better behavior to return a
"Read-only" error message.

Tested:
Performed a Redfish PATCH for the MACAddress property.
The PATCH command returns a 403 error code, and a message body
indicating that the MACAddress is not writable.

Change-Id: Ice97affe694f4bee15436293c9e5944bcae7f4cc
Signed-off-by: Johnathan Mantey <johnathanx.mantey@intel.com>

1 files changed, 16 insertions, 1 deletions

diff --git a/redfish-core/lib/ethernet.hpp b/redfish-core/lib/ethernet.hpp
index 5ccc25fe39..0469f74098 100644
--- a/redfish-core/lib/ethernet.hpp
+++ b/redfish-core/lib/ethernet.hpp
@@ -1123,10 +1123,25 @@ inline void
                           const std::string& macAddress,
                           const std::shared_ptr<bmcweb::AsyncResp>& asyncResp)
 {
+    static constexpr std::string_view dbusNotAllowedError =
+        "xyz.openbmc_project.Common.Error.NotAllowed";
+
     crow::connections::systemBus->async_method_call(
-        [asyncResp, macAddress](const boost::system::error_code ec) {
+        [asyncResp, macAddress](const boost::system::error_code ec,
+                                const sdbusplus::message::message& msg) {
         if (ec)
         {
+            const sd_bus_error* err = msg.get_error();
+            if (err == nullptr)
+            {
+                messages::internalError(asyncResp->res);
+                return;
+            }
+            if (err->name == dbusNotAllowedError)
+            {
+                messages::propertyNotWritable(asyncResp->res, "MACAddress");
+                return;
+            }
             messages::internalError(asyncResp->res);
             return;
         }