No permission to access webApplication properties

Question

When activating a site feature I automaticly want to set a WebApplication property. Even if a farm administrator activates the feature, the security exception is thrown ("access denied").

AFAIK SPSecurity.RunWithElevatedPrivileges runs as a site admin, not farm admin. But HOW can this be done? I tried the following codes:

SPWebServiceCollection wsc = new SPWebServiceCollection(SPFarm.Local);
            foreach (SPWebService ws in wsc)
            {
                SPWebApplicationCollection wac = ws.WebApplications;
                foreach (SPWebApplication wa in wac)
                {
                    try
                    {
                        if (wa.MaxQueryLookupFields < maxLookupFields)
                        {
                            wa.MaxQueryLookupFields = maxLookupFields;
                        }

                    }
                    catch (System.Security.SecurityException ex)
                    {
                        _log.ErrorFormat("Access denied");
                    }
                }
            }

Error at currentApplication.MaxQueryLookupFields = maxLookupFields

another attempt with same Exception:

 SPSecurity.RunWithElevatedPrivileges(delegate()
            {
                SPWeb currentWeb = ContentTypes.ValidateFeatureActivation(properties);
                using (SPSite site = new SPSite(SPContext.Current.Site.ID, SPUserToken.SystemAccount))
                {
                    SPWebApplication currentApplication = site.WebApplication;
                    if (currentApplication.MaxQueryLookupFields < newMaxValue)
                    {
                        try
                        {
                            currentApplication.MaxQueryLookupFields = newMaxValue;
                            success = currentApplication.MaxQueryLookupFields == newMaxValue;
                        }    
                        catch (System.Security.SecurityException ex)
                        {
                            _log.ErrorFormat("no permission");
                        }
                    } else
                    {
                        success = true;
                    }
                }
            });

Answer 1

I think that these properties are stored in Configuration Data Base. By security reason, access to this DB is limmited. This post describes how to solve this issue for self-site creation process. I think that the solution in your case will be the same.