net: config: Verify that the config format hash is not changed

The hash is used to detect whether the yaml schema file is changed.
If the data format in the settings is different that what is found
in the ROM, then the settings db must be discarded because the
data is now incompatible.

Signed-off-by: Jukka Rissanen <[email protected]>

Author: jukkar

subsys/net/lib/config/init.c

@@ -1075,6 +1075,18 @@ int net_config_get(struct net_init_config *cfg)
 		settings_loaded = true;
 	}
 
+	/* Verify that the yaml schema file is not changed between what is in
+	 * use and what was used when the user modified the configuration.
+	 */
+	if (net_init_config_user.config_format_hash != NULL &&
+	    strncmp(config->config_format_hash,
+		    net_init_config_user.config_format_hash,
+		    sizeof(config->config_format_hash) - 1) != 0) {
+		NET_ERR("User network configuration format hash mismatch");
+		settings_loaded = false;
+		return -EINVAL;
+	}
+
 	/* Make a union of the default config and the user modified one and
 	 * return results in cfg pointer.
 	 */