* Oren Laadan <orenl@xxxxxxxxxxxxxxx> wrote: > <3> Clone with pid: > > To restart processes from userspace, there needs to be a way to > request a specific pid--in the current pid_ns--for the child > process (clearly, if it isn't in use). > > Why is it a disadvantage ? to Linus, a syscall clone_with_pid() > "sounds like a _wonderful_ attack vector against badly written > user-land software...". Actually, getting a specific pid is > possible without this syscall. But the point is that it's > undesirable to have this functionality unrestricted. The point is that there's a class of a difference between a racy and unreliable method of 'create tens of thousands of tasks to steal the right PID you are interested in' and a built-in syscall that gives this within a couple of microseconds. Most signal races are timing dependent so the ability to do it really quickly makes or breaks the practicality of many classes of exploits. > So one option is to require root privileges. Another option is to > restrict such action in pid_ns created by the same user. Even more > so, restrict to only containers that are being restarted. Requiring root privileges seems to remove much of the appeal of allowing this to be a more generic sub-container creation thing. If regular unprivileged apps cannot use this to save/restore their own local task hierarchy, the whole thing becomes rather pointless, right? Ingo _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/containers
