Messages in this thread | | | Date | Tue, 23 Jul 2013 14:04:26 -0500 | From | Serge Hallyn <> | Subject | Re: [RFC PATCH 1/2] devices cgroup: allow can_attach() if ns_capable |
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Quoting Tejun Heo (tj@kernel.org): > On Tue, Jul 23, 2013 at 2:38 PM, Serge Hallyn <serge.hallyn@ubuntu.com> wrote: > > This doesn't delegate it into the container. It allows me, on the host, > > to set the cgroup for a container. > > Hmmm? I'm a bit confused. Isn't the description saying that the patch > allows pseudo-root in userns to change cgroup membership even if it > isn't actually root?
If task A is uid 1000 on the host, and creates task B as uid X in a new user namespace, then task A, still being uid 1000 on the host, is privileged with respect to B and his namespace - i.e. ns_capable(B->userns, CAP_SYS_ADMIN) is true.
> Besides, I find the whole check rather bogus and would actually much > prefer just nuking the check and just follow the standard permission > checks.
I'd be ok with that - but there's one case I'm not sure about: If PAM sets me up with /sys/fs/cgroup/devices/serge owned by me, then if I'm thinking right, removing can_attach would mean I could move init into /sys/fs/cgroup/devices/serge...
Is there something else stopping that from happening?
-serge
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