On Fri, Feb 14, 2025 at 12:13:03PM -0600, Elizabeth Figura wrote: > On Friday, 14 February 2025 07:06:20 CST Greg Kroah-Hartman wrote: > > On Fri, Feb 14, 2025 at 12:28:00PM +0000, Mike Lothian wrote: > > > This allows ntsync to be usuable by non-root processes out of the box > > > > Are you sure you need/want that? If so, why? How did existing testing > > not ever catch this? > > Hi, sorry, this is of course my fault. > > We do need /dev/ntsync to be openable from user space for it to be > useful. I'm not sure what the most "correct" permissions are to have > in this case (when we don't specifically need read or write), but I > don't think I see a reason not to just set to 666 or 444. > > I originally assumed that the right way to do this was not to set the > mode on the kernel file but rather through udev; I believe I was using > the code for /dev/loop-control or /dev/fuse as an example, which both > do that. So I (and others who tested) had just manually set up udev > rules for this, with the eventual intent of adding a default rule to > systemd like the others. I only recently realized that doing something > like this patch is possible and precedented. > > I don't know what the best way to address this is, but this is > certainly the simplest. Paranoid defaults in the kernel, and then a udev rule to relax the mode at runtime. You could also have logind scripts to add add per-user allow acls to the device file at user session set up time... or however it is that /dev/sr0 has me on the allow list. I'm not sure how that happens exactly, but it works smoothly. I get far less complaining about relaxing posture than tightening it (==breaking things) after the fact. --D
