devcgroup: fix odd behaviour when writing 'a' to devices.allow
# 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: Li 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/Documentation/controllers/devices.txt b/Documentation/controllers/devices.txt
index 4dcea42..7cc6e6a 100644
--- a/Documentation/controllers/devices.txt
+++ b/Documentation/controllers/devices.txt
@@ -13,7 +13,7 @@
The root device cgroup starts with rwm to 'all'. A child device
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
+never receive a device access which is denied by its parent. However
when a device access is removed from a parent it will not also be
removed from the child(ren).
@@ -29,7 +29,11 @@
echo a > /cgroups/1/devices.deny
-will remove the default 'a *:* mrw' entry.
+will remove the default 'a *:* rwm' entry. Doing
+
+ echo a > /cgroups/1/devices.allow
+
+will add the 'a *:* rwm' entry to the whitelist.
3. Security