[cgmanager-devel] getTasks method
stgraber at ubuntu.com
Wed Jan 15 22:10:36 UTC 2014
On Wed, Jan 15, 2014 at 03:21:28PM -0600, Serge Hallyn wrote:
> One method which somehow never made it into my design is nrtasks, to
> return the list of tasks in the container.
> For the non-scm, same-pidns version, this could return a dbus array
> of int32s. For the scm version, I only see two possibilities. The
> potentially insecure one involves sending an fd for the open tasks
> file over SCM. The client can then read the file, which should have
> pids translated to the client's pidns.
Are you sure this would work?
I quickly tried in a container doing:
echo 1 > /sys/fs/cgroup/devices/tasks
Then in the same container in a python shell:
And finally from outside the container:
cat /proc/<pid of python shell>/fd/3
Which didn't give me the translated PID of PID 1 but instead a whole ton
of completely unrelated entries (no idea why...).
> The other possibility, which I'll go with unless I hear better ideas,
> is to send back to the client (which is the proxy) (1) an integer n saying
> how many tasks there are, followed by n scm_creds to send the pids,
> which will be translated en route by the kernel.
> Any other ideas?
> cgmanager-devel mailing list
> cgmanager-devel at lists.linuxcontainers.org
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