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authorAristeu Rozanski <aris@redhat.com>2012-11-06 07:25:04 -0800
committerTejun Heo <tj@kernel.org>2012-11-06 07:25:20 -0800
commit64e104771351d365e51e588a0e9a656ae6ed2f50 (patch)
treee5078e0ba32729735846aa465c1f53f5d98c11ac /security/device_cgroup.c
parent3d70f8c617a436c7146ecb81df2265b4626dfe89 (diff)
downloadvexpress-lsk-64e104771351d365e51e588a0e9a656ae6ed2f50.tar.gz
device_cgroup: fix unchecked cgroup parent usage
In 4cef7299b478687 ("device_cgroup: add proper checking when changing default behavior") the cgroup parent usage is unchecked. root will not have a parent and trying to use device.{allow,deny} will cause problems. For some reason my stressing scripts didn't test the root directory so I didn't catch it on my regular tests. Signed-off-by: Aristeu Rozanski <aris@redhat.com> Cc: Li Zefan <lizefan@huawei.com> Cc: James Morris <jmorris@namei.org> Cc: Pavel Emelyanov <xemul@openvz.org> Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'security/device_cgroup.c')
-rw-r--r--security/device_cgroup.c12
1 files changed, 10 insertions, 2 deletions
diff --git a/security/device_cgroup.c b/security/device_cgroup.c
index 842c254396d..96d87eab166 100644
--- a/security/device_cgroup.c
+++ b/security/device_cgroup.c
@@ -352,6 +352,8 @@ static int parent_has_perm(struct dev_cgroup *childcg,
*/
static inline int may_allow_all(struct dev_cgroup *parent)
{
+ if (!parent)
+ return 1;
return parent->behavior == DEVCG_DEFAULT_ALLOW;
}
@@ -376,11 +378,14 @@ static int devcgroup_update_access(struct dev_cgroup *devcgroup,
int count, rc;
struct dev_exception_item ex;
struct cgroup *p = devcgroup->css.cgroup;
- struct dev_cgroup *parent = cgroup_to_devcgroup(p->parent);
+ struct dev_cgroup *parent = NULL;
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
+ if (p->parent)
+ parent = cgroup_to_devcgroup(p->parent);
+
memset(&ex, 0, sizeof(ex));
b = buffer;
@@ -391,11 +396,14 @@ static int devcgroup_update_access(struct dev_cgroup *devcgroup,
if (!may_allow_all(parent))
return -EPERM;
dev_exception_clean(devcgroup);
+ devcgroup->behavior = DEVCG_DEFAULT_ALLOW;
+ if (!parent)
+ break;
+
rc = dev_exceptions_copy(&devcgroup->exceptions,
&parent->exceptions);
if (rc)
return rc;
- devcgroup->behavior = DEVCG_DEFAULT_ALLOW;
break;
case DEVCG_DENY:
dev_exception_clean(devcgroup);