Eric W. Biederman [ebied...@xmission.com] wrote:
| > | + if (target < RESERVED_PIDS)
| >
| > Should we replace RESERVED_PIDS with 0 ? We currently allow new
| > containers to have pids 1..32K in the first pass and in subsequent
| > passes assign starting at RESERVED_PIDS.
|
| If it is a preexisting namespace pid namespace removing the RESERVED_PIDS
| check removes most if not all of the point of RESERVED_PIDS.
|
| In a new fresh pid namespace I have no problem with not performing
| the RESERVED_PIDS check.
In that case can we do this
if (target_pid < RESERVED_PIDS && !pid_ns->level)
return -EINVAL;
instead ?
|
| So I guess that makes the check.
|
| if ((target < RESERVED_PIDS) && pid_ns->last_pid >= RESERVED_PIDS)
| return -EINVAL;
I am just wondering if there is a small corner case where C/R would randomly
fail because of this sequence:
- C/R code calls clone() or clone3() say about RESERVED_PIDS-1
times and ->last_pid == RESERVED_PIDS-1.
- C/R code calls normal fork()/alloc_pidmap() for a short-lived
child - its pid == ->last_pid == RESERVED_PIDS
- C/R code then calls clone3()/set_pidmap() to set the pid of
a new child to RESERVED_PID but fails (i.e it fails to restore
a pid even when the pid is not in use).
We could argue that mixing alloc_pidmap() and set_pidmap() during restart
is bad since set_pidmap() may fail.
The C/R developer could argue that we are forcing them to specify a pid
even for a short lived process that they wait()s on and thus ensure that
pid is not in use.
Anyway, is RESERVED_PIDS meant for initial kernel-threads/daemons - if so
would it be ok enforce it only in init_pid_ns ?
Sukadev
_______________________________________________
Containers mailing list
contain...@lists.linux-foundation.org
https://lists.linux-foundation.org/mailman/listinfo/containers
_______________________________________________
Devel mailing list
Devel@openvz.org
https://openvz.org/mailman/listinfo/devel
