On Fri, Nov 16, 2018 at 10:45:11AM +0100, Paolo Bonzini wrote: > Yeah, but looking at the command is what Ted wants. The thing that we > did in RHEL was a single sysfs bool that allows unfiltered access, > because it was sort of enough and made the delta very small. But for > upstream I want to do it right, even if that means learning all that > new-fangled BPF stuff. :) So what is this magic command? > I would even agree, however it's allowed right now and I would be > surprised if no one was relying on it in good faith ("I'm just doing an > INQUIRY, why do I need to open O_RDWR"). And indeed: > > $ sudo chmod a+r /dev/sda > $ strace -e openat sg_inq /dev/sda > openat(AT_FDCWD, "/dev/sda", O_RDONLY|O_NONBLOCK) = 3 Well, not if we only did that for unprivileged opens.