111 lines
2.5 KiB
C
111 lines
2.5 KiB
C
/*
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* ns_cgroup.c - namespace cgroup subsystem
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*
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* Copyright 2006, 2007 IBM Corp
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*/
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#include <linux/module.h>
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#include <linux/cgroup.h>
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#include <linux/fs.h>
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#include <linux/proc_fs.h>
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#include <linux/slab.h>
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#include <linux/nsproxy.h>
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struct ns_cgroup {
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struct cgroup_subsys_state css;
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};
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struct cgroup_subsys ns_subsys;
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static inline struct ns_cgroup *cgroup_to_ns(
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struct cgroup *cgroup)
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{
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return container_of(cgroup_subsys_state(cgroup, ns_subsys_id),
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struct ns_cgroup, css);
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}
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int ns_cgroup_clone(struct task_struct *task, struct pid *pid)
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{
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char name[PROC_NUMBUF];
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snprintf(name, PROC_NUMBUF, "%d", pid_vnr(pid));
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return cgroup_clone(task, &ns_subsys, name);
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}
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/*
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* Rules:
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* 1. you can only enter a cgroup which is a descendant of your current
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* cgroup
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* 2. you can only place another process into a cgroup if
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* a. you have CAP_SYS_ADMIN
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* b. your cgroup is an ancestor of task's destination cgroup
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* (hence either you are in the same cgroup as task, or in an
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* ancestor cgroup thereof)
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*/
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static int ns_can_attach(struct cgroup_subsys *ss, struct cgroup *new_cgroup,
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struct task_struct *task, bool threadgroup)
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{
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if (current != task) {
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if (!capable(CAP_SYS_ADMIN))
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return -EPERM;
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if (!cgroup_is_descendant(new_cgroup, current))
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return -EPERM;
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}
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if (!cgroup_is_descendant(new_cgroup, task))
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return -EPERM;
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if (threadgroup) {
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struct task_struct *c;
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rcu_read_lock();
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list_for_each_entry_rcu(c, &task->thread_group, thread_group) {
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if (!cgroup_is_descendant(new_cgroup, c)) {
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rcu_read_unlock();
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return -EPERM;
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}
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}
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rcu_read_unlock();
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}
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return 0;
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}
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/*
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* Rules: you can only create a cgroup if
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* 1. you are capable(CAP_SYS_ADMIN)
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* 2. the target cgroup is a descendant of your own cgroup
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*/
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static struct cgroup_subsys_state *ns_create(struct cgroup_subsys *ss,
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struct cgroup *cgroup)
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{
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struct ns_cgroup *ns_cgroup;
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if (!capable(CAP_SYS_ADMIN))
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return ERR_PTR(-EPERM);
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if (!cgroup_is_descendant(cgroup, current))
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return ERR_PTR(-EPERM);
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ns_cgroup = kzalloc(sizeof(*ns_cgroup), GFP_KERNEL);
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if (!ns_cgroup)
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return ERR_PTR(-ENOMEM);
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return &ns_cgroup->css;
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}
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static void ns_destroy(struct cgroup_subsys *ss,
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struct cgroup *cgroup)
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{
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struct ns_cgroup *ns_cgroup;
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ns_cgroup = cgroup_to_ns(cgroup);
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kfree(ns_cgroup);
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}
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struct cgroup_subsys ns_subsys = {
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.name = "ns",
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.can_attach = ns_can_attach,
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.create = ns_create,
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.destroy = ns_destroy,
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.subsys_id = ns_subsys_id,
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};
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