[PATCH 1/1] Don't allow user namespaces to bind new subsystems

[Serge Hallyn]

If memory was not mounted on the host, then root in a container
should not be able to mount it.

Signed-off-by: Serge Hallyn <serge.hallyn@xxxxxxxxxx>
---
 kernel/cgroup.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 0a3e893..db514b4 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -2102,6 +2102,11 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type,
 		goto out_unlock;
 	}
 
+	if (!opts.none && !capable(CAP_SYS_ADMIN)) {
+		ret = -EPERM;
+		goto out_unlock;
+	}
+
 	root = kzalloc(sizeof(*root), GFP_KERNEL);
 	if (!root) {
 		ret = -ENOMEM;
-- 
2.5.0

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