Quoting Eric W. Biederman (ebiederm@xxxxxxxxxxxx): > "Serge E. Hallyn" <serge@xxxxxxxxxx> writes: > > > Quoting Eric W. Biederman (ebiederm@xxxxxxxxxxxx): > >> > >> I goofed when I made unshare(CLONE_NEWPID) only work in a > >> single-threaded process. There is no need for that requirement and in > >> fact I analyzied things right for setns. The hard requirement > >> is for tasks that share a VM to all be in the pid namespace and > >> we properly prevent that in do_fork. > > > > I don't understand though - copy_process does have the right test: > > > > 1176 * If the new process will be in a different pid namespace > > 1177 * don't allow the creation of threads. > > 1178 */ > > 1179 if ((clone_flags & (CLONE_VM|CLONE_NEWPID)) && > > 1180 (task_active_pid_ns(current) != current->nsproxy->pid_ns)) > > 1181 return ERR_PTR(-EINVAL); > > > > but why is it ok for sys_unshare not to do that? Note that > > in order for check_unshare_flags() to bail on ¤t->mm->mm_users > 1 > > you do have to set CLONE_VM (for inverse interpretation). > > > > So it seems to me this isn't safe as is, and we need to at least > > set CLONE_VM if CLONE_PID is set. > > Partly this is the difference in the meaning of the flags between > unshare and clone. > > Basically in unshare all othat gets changed is > current->nsproxy->pid_ns_for_children (the rename is in the net tree). D'oh, right. Thanks! Acked-by: Serge Hallyn <serge.hallyn@xxxxxxxxxxxxx> > So because unshare of the pid namespace does not actually effect the > current processes, just the pid namespace the children of the current > thread will be in this is safe. > > And frankly having the checks be obviously different is a good thing > because it means that people will ask why in the world this is so and > realize the difference in meaning. > > Eric _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/containers
