Quoting sukadev@xxxxxxxxxx (sukadev@xxxxxxxxxx): > Serge E. Hallyn [serue@xxxxxxxxxx] wrote: > | > | I suppose you could just create /dev/pts/ptmx and /dev/pts/tty. > | > | Recommend that in containers /dev/ptmx and /dev/tty be symlinks > | > | into /dev/pts. Applications don't need to change. If > | > | ptmx_open() sees that inode->i_sb is a devptsfs, it gets the > | > | namespace from the sb. If not, then it was a device in /dev > | > | and it gets the nmespace from current. > | > > | > But we would still depend on user-space remounting /dev/pts after > | > the clone right ? Until they do that we would access the parent > | > container's /dev/pts/ptmx ? > | > | Yes. Which is the right thing to do imo. > > Hmm, that sounds reasonable, although slightly inconsistent with pid-ns, > where pid starts at 1 regardless of whether /proc is remounted. Very different cases. The pid is the task's pid in the new pidns. The task ALSO has a different pid in the parent pidns. The pts only has an identity in one ptsns. > But even so, if user fails to establish the symlink, clones the pts ns > and tries to create a pty, we would end up with different pts nses again ? Yes. So what? > i.e > /dev/ptmx is still a char dev in root fs > clone(pts_ns) > ( In child, (before remount /dev/pts)) > open("/dev/ptmx") > open("/dev/pts/0") > > Since ptmx is not in devpts, we use current_pts_ns() or child-pts-ns > Since /dev/pts is not remounted in child, we get the parent pts-ns from > > If we can somehow detect the incorrect configuration and fail either > open, we should be ok :-) I completely disagree with this sentiment. The kernel doesn't need to detect an "incorrect configuration" if it isn't dangerous. One man's "incorrect configuration" is another man's useful trick. -serge _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/containers