Quoting Kay Sievers (kay.sievers@xxxxxxxx): > On Tue, Jan 24, 2012 at 23:02, Serge E. Hallyn <serge@xxxxxxxxxx> wrote: > > Quoting Eric W. Biederman (ebiederm@xxxxxxxxxxxx): > > >> It looks like relatively recent udev still creates /dev/ptmx and does > > > > Boy, it does, and it's stubborn about it. Removing the /lib/udev/rules.d > > entry doesn't stop it. (this is after I've had an init job replace the > > devtmpfs-created ptmx entry with a symlink) > > Udev has nothing to do with that. The kernel creates that device node. > Udev does not carry any rules you could remove, to name device nodes, > it only set permissions and creates symlinks to device nodes. That's odd, because I was sure I deleted the node after the kernel created it. But it sounds like I must have done it wrong. > It will never replace a kernel-created device node with a symlink, > there is no way to express that. If you don't want a device node > there, you need to change the kernel, to not export > /sys/class/tty/ptmx/ the way it is today. > > > So current distros (well, Ubuntu and Fedora at least) would need to at least > > (a) fix udev, > > To do what? Nothing, as I'm sure you're right above :) > > (b) change the default devpts mount (done from initramfs) to > > add ptmxmode=666, > > > (c) (if not done in udev) create the /dev/ptmx symlink. > > Udev can only create symlinks to devices the driver-core creates, not > to devices inside a custom filesystem. I see. > > For safety I'd recommend creating /dev/pts/ptmx with > > DEVPTS_MULTIPLE_INSTANCES=n (or dropping that support), and by default > > setting ptmxmode to 666 as that's what udev does. > > The mode for ptmx is set by the kernel itself, and does not even need > udev to do that: > $ cat /sys/class/tty/ptmx/uevent > MAJOR=5 > MINOR=2 > DEVNAME=ptmx > DEVMODE=0666 That has nothing to do with /dev/pts/ptmx, whose perms are set based on the '-o ptmxmode=" argument, and default to 000 if not specified. If /dev/ptmx is going to be a symlink to /dev/pts/ptmx, then we have to set the /dev/pts/ptmx perms to not be 000, or users won't be able to create ptys. -serge _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/containers
