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    SubjectRe: [PATCH 1/1] cgroups: implement device whitelist (v6)
    Andrew Morton wrote:
    > On Wed, 26 Mar 2008 13:05:43 -0500 "Serge E. Hallyn" <> wrote:
    >> (This is identical to the version I sent on Mar 19 in response to
    >> the comments by Daniel Hokka Zakrisson, which are the last
    >> comments I've gotten.)
    >> Implement a cgroup to track and enforce open and mknod restrictions on device
    >> files. A device cgroup associates a device access whitelist with each
    >> cgroup. A whitelist entry has 4 fields. 'type' is a (all), c (char), or
    >> b (block). 'all' means it applies to all types and all major and minor
    >> numbers. Major and minor are either an integer or * for all.
    >> Access is a composition of r (read), w (write), and m (mknod).
    >> The root device cgroup starts with rwm to 'all'. A child devcg gets
    >> a copy of the parent. Admins 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).
    >> An entry is added using devices.allow, and removed using
    >> devices.deny. For instance
    >> echo 'c 1:3 mr' > /cgroups/1/devices.allow
    >> allows cgroup 1 to read and mknod the device usually known as
    >> /dev/null. Doing
    >> echo a > /cgroups/1/devices.deny
    >> will remove the default 'a *:* mrw' entry.
    >> CAP_SYS_ADMIN is needed to change permissions or move another task
    >> to a new cgroup. A cgroup may not be granted more permissions than
    >> the cgroup's parent has. Any task can move itself between cgroups.
    >> This won't be sufficient, but we can decide the best way to
    >> adequately restrict movement later.
    > The above should be in Documentation/cgroups.txt?

    You mean to add a Documentation/controller/devices.txt? ;)

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