2 * ns_cgroup.c - namespace cgroup subsystem
4 * Copyright 2006, 2007 IBM Corp
7 #include <linux/module.h>
8 #include <linux/cgroup.h>
10 #include <linux/proc_fs.h>
11 #include <linux/slab.h>
12 #include <linux/nsproxy.h>
15 struct cgroup_subsys_state css;
18 struct cgroup_subsys ns_subsys;
20 static inline struct ns_cgroup *cgroup_to_ns(
21 struct cgroup *cgroup)
23 return container_of(cgroup_subsys_state(cgroup, ns_subsys_id),
24 struct ns_cgroup, css);
27 int ns_cgroup_clone(struct task_struct *task, struct pid *pid)
29 char name[PROC_NUMBUF];
31 snprintf(name, PROC_NUMBUF, "%d", pid_vnr(pid));
32 return cgroup_clone(task, &ns_subsys, name);
37 * 1. you can only enter a cgroup which is a descendant of your current
39 * 2. you can only place another process into a cgroup if
40 * a. you have CAP_SYS_ADMIN
41 * b. your cgroup is an ancestor of task's destination cgroup
42 * (hence either you are in the same cgroup as task, or in an
43 * ancestor cgroup thereof)
45 static int ns_can_attach(struct cgroup_subsys *ss, struct cgroup *new_cgroup,
46 struct task_struct *task, bool threadgroup)
48 if (current != task) {
49 if (!capable(CAP_SYS_ADMIN))
52 if (!cgroup_is_descendant(new_cgroup, current))
56 if (!cgroup_is_descendant(new_cgroup, task))
60 struct task_struct *c;
62 list_for_each_entry_rcu(c, &task->thread_group, thread_group) {
63 if (!cgroup_is_descendant(new_cgroup, c)) {
75 * Rules: you can only create a cgroup if
76 * 1. you are capable(CAP_SYS_ADMIN)
77 * 2. the target cgroup is a descendant of your own cgroup
79 static struct cgroup_subsys_state *ns_create(struct cgroup_subsys *ss,
80 struct cgroup *cgroup)
82 struct ns_cgroup *ns_cgroup;
84 if (!capable(CAP_SYS_ADMIN))
85 return ERR_PTR(-EPERM);
86 if (!cgroup_is_descendant(cgroup, current))
87 return ERR_PTR(-EPERM);
89 ns_cgroup = kzalloc(sizeof(*ns_cgroup), GFP_KERNEL);
91 return ERR_PTR(-ENOMEM);
92 return &ns_cgroup->css;
95 static void ns_destroy(struct cgroup_subsys *ss,
96 struct cgroup *cgroup)
98 struct ns_cgroup *ns_cgroup;
100 ns_cgroup = cgroup_to_ns(cgroup);
104 struct cgroup_subsys ns_subsys = {
106 .can_attach = ns_can_attach,
108 .destroy = ns_destroy,
109 .subsys_id = ns_subsys_id,