setns on a cgroup namespace is allowed only if
task has CAP_SYS_ADMIN in its current user-namespace and
over the user-namespace associated with target cgroupns.
No implicit cgroup changes happen with attaching to another
cgroupns. It is expected that the somone moves the attaching
process under the target cgroupns-root.
Signed-off-by: Aditya Kali <adityakali@xxxxxxxxxx>
---
kernel/cgroup_namespace.c | 18 ++++++++++++++++--
1 file changed, 16 insertions(+), 2 deletions(-)
diff --git a/kernel/cgroup_namespace.c b/kernel/cgroup_namespace.c
index 7e9bda0..0803575 100644
--- a/kernel/cgroup_namespace.c
+++ b/kernel/cgroup_namespace.c
@@ -86,8 +86,22 @@ err_out:
static int cgroupns_install(struct nsproxy *nsproxy, void *ns)
{
- pr_info("setns not supported for cgroup namespace");
- return -EINVAL;
+ struct cgroup_namespace *cgroup_ns = ns;
+
+ if (!ns_capable(current_user_ns(), CAP_SYS_ADMIN) ||
+ !ns_capable(cgroup_ns->user_ns, CAP_SYS_ADMIN))
+ return -EPERM;
+
+ /* Prevent cgroup changes for this task. */
+ threadgroup_lock(current);
+
+ get_cgroup_ns(cgroup_ns);
+ put_cgroup_ns(nsproxy->cgroup_ns);
+ nsproxy->cgroup_ns = cgroup_ns;
+
+ threadgroup_unlock(current);
+
+ return 0;
}
static void *cgroupns_get(struct task_struct *task)
--
2.1.0.rc2.206.gedb03e5
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