[PATCH v2 1/6] device_cgroup: add "behavior" in dev_cgroup structure

[Aristeu Rozanski]

behavior will determine if the default policy is to deny all device access
unless for the ones in the exception list.

This variable will be used in the next patches to convert device_cgroup
internally into a default policy + rules.

v2:
- renamed deny_all to behavior

Cc: Tejun Heo <tj@xxxxxxxxxx>
Cc: Li Zefan <lizefan@xxxxxxxxxx>
Cc: James Morris <jmorris@xxxxxxxxx>
Cc: Pavel Emelyanov <xemul@xxxxxxxxxx>
Cc: Serge Hallyn <serge.hallyn@xxxxxxxxxxxxx>
Signed-off-by: Aristeu Rozanski <aris@xxxxxxxxxx>

---
 security/device_cgroup.c |    8 ++++++++
 1 file changed, 8 insertions(+)

Index: github/security/device_cgroup.c
===================================================================
--- github.orig/security/device_cgroup.c	2012-08-21 09:49:38.698415513 -0400
+++ github/security/device_cgroup.c	2012-08-21 10:50:34.650810797 -0400
@@ -42,6 +42,10 @@
 struct dev_cgroup {
 	struct cgroup_subsys_state css;
 	struct list_head whitelist;
+	enum {
+		DEVCG_DEFAULT_ALLOW,
+		DEVCG_DEFAULT_DENY,
+	} behavior;
 };
 
 static inline struct dev_cgroup *css_to_devcgroup(struct cgroup_subsys_state *s)
@@ -178,12 +182,14 @@
 		wh->minor = wh->major = ~0;
 		wh->type = DEV_ALL;
 		wh->access = ACC_MASK;
+		dev_cgroup->behavior = DEVCG_DEFAULT_ALLOW;
 		list_add(&wh->list, &dev_cgroup->whitelist);
 	} else {
 		parent_dev_cgroup = cgroup_to_devcgroup(parent_cgroup);
 		mutex_lock(&devcgroup_mutex);
 		ret = dev_whitelist_copy(&dev_cgroup->whitelist,
 				&parent_dev_cgroup->whitelist);
+		dev_cgroup->behavior = parent_dev_cgroup->behavior;
 		mutex_unlock(&devcgroup_mutex);
 		if (ret) {
 			kfree(dev_cgroup);
@@ -409,9 +415,11 @@
 	case DEVCG_ALLOW:
 		if (!parent_has_perm(devcgroup, &wh))
 			return -EPERM;
+		devcgroup->behavior = DEVCG_DEFAULT_ALLOW;
 		return dev_whitelist_add(devcgroup, &wh);
 	case DEVCG_DENY:
 		dev_whitelist_rm(devcgroup, &wh);
+		devcgroup->behavior = DEVCG_DEFAULT_DENY;
 		break;
 	default:
 		return -EINVAL;

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