Minor typo and spelling corrections fixed whilst reading
to learn about cgroups capabilities.
Signed-off-by: NChris Samuel <chris@csamuel.org>
Acked-by: NPaul Menage <menage@google.com>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>

Move Documentation/cpusets.txt and Documentation/controllers/* to
Documentation/cgroups/
Signed-off-by: NLi Zefan <lizf@cn.fujitsu.com>
Acked-by: NKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: NBalbir Singh <balbir@linux.vnet.ibm.com>
Acked-by: NPaul Menage <menage@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

 # cat /devcg/devices.list
 a *:* rwm
 # echo a > devices.allow
 # cat /devcg/devices.list
 a *:* rwm
 a 0:0 rwm

This is odd and maybe confusing.  With this patch, writing 'a' to
devices.allow will add 'a *:* rwm' to the whitelist.

Also a few fixes and updates to the document.
Signed-off-by: NLi Zefan <lizf@cn.fujitsu.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Serge E. Hallyn <serue@us.ibm.com>
Cc: Paul Menage <menage@google.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: James Morris <jmorris@namei.org>
Cc: Chris Wright <chrisw@sous-sol.org>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

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.

[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: fix may-be-used-uninitialized warning]
Signed-off-by: NSerge E. Hallyn <serue@us.ibm.com>
Acked-by: NJames Morris <jmorris@namei.org>
Looks-good-to: Pavel Emelyanov <xemul@openvz.org>
Cc: Daniel Hokka Zakrisson <daniel@hozac.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Paul Menage <menage@google.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>