From d823f6bfec2844493c05961133895de21fa0e02d Mon Sep 17 00:00:00 2001 From: Li Zefan <lizf@cn.fujitsu.com> Date: Fri, 4 Jul 2008 10:00:07 -0700 Subject: [PATCH] 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> --- Documentation/controllers/devices.txt | 8 ++++++-- security/device_cgroup.c | 2 ++ 2 files changed, 8 insertions(+), 2 deletions(-) diff --git a/Documentation/controllers/devices.txt b/Documentation/controllers/devices.txt index 4dcea42432c27..7cc6e6a60672c 100644 --- a/Documentation/controllers/devices.txt +++ b/Documentation/controllers/devices.txt @@ -13,7 +13,7 @@ either an integer or * for all. Access is a composition of r 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 @@ allows cgroup 1 to read and mknod the device usually known as 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 diff --git a/security/device_cgroup.c b/security/device_cgroup.c index baf348834b66c..fd764a0858d0d 100644 --- a/security/device_cgroup.c +++ b/security/device_cgroup.c @@ -382,6 +382,8 @@ static ssize_t devcgroup_access_write(struct cgroup *cgroup, struct cftype *cft, case 'a': wh.type = DEV_ALL; wh.access = ACC_MASK; + wh.major = ~0; + wh.minor = ~0; goto handle; case 'b': wh.type = DEV_BLOCK; -- GitLab