Re: [PATCH] cgroups: devices: add Documentation/ file

From: Randy Dunlap
Date: Thu Mar 27 2008 - 12:02:32 EST


On Thu, 27 Mar 2008 10:12:27 -0500 Serge E. Hallyn wrote:

> Fill a Documentation/controllers/devices.txt file with a
> modified text from the patch description.
>
> Signed-off-by: Serge E. Hallyn <serue@xxxxxxxxxx>
> ---
> Documentation/controllers/devices.txt | 48 +++++++++++++++++++++++++++++++++
> 1 files changed, 48 insertions(+), 0 deletions(-)
> create mode 100644 Documentation/controllers/devices.txt
>
> diff --git a/Documentation/controllers/devices.txt b/Documentation/controllers/devices.txt
> new file mode 100644
> index 0000000..a157f53
> --- /dev/null
> +++ b/Documentation/controllers/devices.txt
> @@ -0,0 +1,48 @@
> +Device Whitelist Controller
> +
> +1. Description:
> +

...

> +The root device cgroup starts with rwm to 'all'. A child devices

device's

> +cgroup gets a copy of the parent. Administrators can then remove
> +devices from the whitelist or add new entries. A child cgroup can
> +never receive a device access which is denied its parent. However
> +when a device access is removed from a parent it will not also be
> +removed from the child(ren).
> +
> +2. User Interface
> +
...
> +
> +3. Security
> +
> +Any task can move itself between cgroups. This of clearly won't

s/of//

> +suffice, but we can decide the best way to adequately restrict
> +movement as people get some experience with this. We may just want
> +to require CAP_SYS_ADMIN, which at least is a separate bit from
> +CAP_MKNOD. We may want to just refuse moving to a cgroup which
> +isn't a descendent of the current one. Or we may want to use
> +CAP_MAC_ADMIN, since we really are trying to lock down root.
> +
> +CAP_SYS_ADMIN is needed to modify the whitelist or move another
> +task to a new cgroup. (Again we'll probably want to change that).
> +
> +A cgroup may not be granted more permissions than the cgroup's
> +parent has.
> --

---
~Randy
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