linux/init
Serge E. Hallyn 08ce5f16ee cgroups: implement device whitelist
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: Serge E. Hallyn <serue@us.ibm.com>
Acked-by: James 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-04-29 08:06:09 -07:00
..
calibrate.c calibrate_delay() must be __cpuinit 2008-02-06 10:41:08 -08:00
do_mounts.c Use struct path in fs_struct 2008-02-14 21:13:33 -08:00
do_mounts.h Remove all inclusions of <linux/config.h> 2006-10-04 03:38:54 -04:00
do_mounts_initrd.c Freezer: Fix s2disk resume from initrd 2007-11-20 22:22:42 -05:00
do_mounts_md.c init: fix integer as NULL pointer warnings 2008-04-28 17:29:18 -07:00
do_mounts_rd.c init: fix integer as NULL pointer warnings 2008-04-28 17:29:18 -07:00
initramfs.c directly use kmalloc() and kfree() in init/initramfs.c 2008-04-29 08:06:06 -07:00
Kconfig cgroups: implement device whitelist 2008-04-29 08:06:09 -07:00
main.c Simplify initcall_debug output 2008-04-29 08:06:02 -07:00
Makefile kbuild: fix make V=1 2008-02-11 17:43:54 +01:00
noinitramfs.c [PATCH] disable init/initramfs.c 2007-02-11 10:51:25 -08:00
version.c [PATCH] remove many unneeded #includes of sched.h 2007-02-14 08:09:54 -08:00