> Its unfortunate that applications use loopback to do their own local > IPC. Such applications are inherently busted IMO (unless they are > *intended* to operate over the network as well as locally), since they > rely on a correct network configuration and wind up utilizing a lot of > extra overhead associated with TCP/IP that a simpler IPC could elide.
I don't think such applications are "inherently busted". Given that the operating system itself sets up loopback and moreover that loopback configuration has nothing to do with broader network configuration, it seems perfectly reasonable to assume it to be correct, and Solaris features like TCP fusion make it quite fast. However, this is also an irrelevant debate: the fact is that applications have been free to use loopback AF_INET for IPC for decades and invariably some have done so. Those applications will be broken by this privilege that was never intended to restrict IPC. I see two paths forward: redefine the privilege to include the wart of restricting loopback AF_INET IPC (and to rework impacted applications as the need arises -- including third-party applications), or to design a different mechanism to implement this restriction. FWIW, I do not consider leaving this matter an undocumented side effect and crossing our fingers as an option. -- meem
