Brent Casavant <[EMAIL PROTECTED]> wrote: [...] > I could mmap a temporary tmpfs file (tmpfs so that if there is a > machine crash no sensitive data persists) which is created with > permissions of 0, immediately unlink it, and pass the file > descriptor through an AF_UNIX socket. This does open up a very > small window of vulnerability if another process is able to chmod > the file and open it before the unlink.
If the process can chmod the file, it can ptrace the daemon, too. Or, using CAP_DAC_OVERRIDE, it can patch the daemon. Both will void any security. > However, it occurs to me that this problem goes away if there were > a method create a file in an unlinked state to begin with. However > there does not appear to be any such mechanism in Linux's open() > interface. Having no window for creating stale temp files is nice to have. We only need a clever fool to implement it.-) But since it's hard to get killed just in the right moment for having a stale temp file, there is very low interest for this feature. -- You know you're in trouble when packet floods are competing to flood you. -- grc.com Friß, Spammer: [EMAIL PROTECTED] [EMAIL PROTECTED] - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/