[PATCHv1 7/8] cgroup: cgroup namespace setns support
From: Aditya Kali <hidden>
Date: 2014-10-13 21:24:30
Also in:
linux-api, lkml
Subsystem:
the rest · Maintainer:
Linus Torvalds
Possibly related (same subject, not in this thread)
- 2014-10-22 · Re: [PATCHv1 7/8] cgroup: cgroup namespace setns support · Tejun Heo <tj@kernel.org>
- 2014-10-22 · Re: [PATCHv1 7/8] cgroup: cgroup namespace setns support · Andy Lutomirski <luto@amacapital.net>
- 2014-10-22 · Re: [PATCHv1 7/8] cgroup: cgroup namespace setns support · Aditya Kali <hidden>
- 2014-10-22 · Re: [PATCHv1 7/8] cgroup: cgroup namespace setns support · Andy Lutomirski <luto@amacapital.net>
- 2014-10-22 · Re: [PATCHv1 7/8] cgroup: cgroup namespace setns support · Aditya Kali <hidden>
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. * task's current cgroup is descendent of the target cgroupns-root cgroup. * target cgroupns-root is same as or deeper than task's current cgroupns-root. This is so that the task cannot escape out of its cgroupns-root. This also ensures that setns() only makes the task get restricted to a deeper cgroup hierarchy. Signed-off-by: Aditya Kali <redacted> --- kernel/cgroup_namespace.c | 44 ++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 42 insertions(+), 2 deletions(-)
diff --git a/kernel/cgroup_namespace.c b/kernel/cgroup_namespace.c
index c16604f..c612946 100644
--- a/kernel/cgroup_namespace.c
+++ b/kernel/cgroup_namespace.c@@ -80,8 +80,48 @@ 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; + struct task_struct *task = current; + struct cgroup *cgrp = NULL; + int err = 0; + + 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(task); + + cgrp = get_task_cgroup(task); + + err = -EINVAL; + if (!cgroup_on_dfl(cgrp)) + goto out_unlock; + + /* Allow switch only if the task's current cgroup is descendant of the + * target cgroup_ns->root_cgrp. + */ + if (!cgroup_is_descendant(cgrp, cgroup_ns->root_cgrp)) + goto out_unlock; + + /* Only allow setns to a cgroupns root-ed deeper than task's current + * cgroupns-root. This will make sure that tasks cannot escape their + * cgroupns by attaching to parent cgroupns. + */ + if (!cgroup_is_descendant(cgroup_ns->root_cgrp, + task_cgroupns_root(task))) + goto out_unlock; + + err = 0; + get_cgroup_ns(cgroup_ns); + put_cgroup_ns(nsproxy->cgroup_ns); + nsproxy->cgroup_ns = cgroup_ns; + +out_unlock: + threadgroup_unlock(current); + if (cgrp) + cgroup_put(cgrp); + return err; } static void *cgroupns_get(struct task_struct *task)
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2.1.0.rc2.206.gedb03e5