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;
19 struct cgroup_subsys ns_subsys;
21 static inline struct ns_cgroup *cgroup_to_ns(
22 struct cgroup *cgroup)
24 return container_of(cgroup_subsys_state(cgroup, ns_subsys_id),
25 struct ns_cgroup, css);
28 int ns_cgroup_clone(struct task_struct *task, struct pid *pid)
30 char name[PROC_NUMBUF];
32 snprintf(name, PROC_NUMBUF, "%d", pid_vnr(pid));
33 return cgroup_clone(task, &ns_subsys, name);
38 * 1. you can only enter a cgroup which is a child of your current
40 * 2. you can only place another process into a cgroup if
41 * a. you have CAP_SYS_ADMIN
42 * b. your cgroup is an ancestor of task's destination cgroup
43 * (hence either you are in the same cgroup as task, or in an
44 * ancestor cgroup thereof)
46 static int ns_can_attach(struct cgroup_subsys *ss,
47 struct cgroup *new_cgroup, struct task_struct *task)
51 if (current != task) {
52 if (!capable(CAP_SYS_ADMIN))
55 if (!cgroup_is_descendant(new_cgroup))
59 if (atomic_read(&new_cgroup->count) != 0)
62 orig = task_cgroup(task, ns_subsys_id);
63 if (orig && orig != new_cgroup->parent)
70 * Rules: you can only create a cgroup if
71 * 1. you are capable(CAP_SYS_ADMIN)
72 * 2. the target cgroup is a descendant of your own cgroup
74 static struct cgroup_subsys_state *ns_create(struct cgroup_subsys *ss,
75 struct cgroup *cgroup)
77 struct ns_cgroup *ns_cgroup;
79 if (!capable(CAP_SYS_ADMIN))
80 return ERR_PTR(-EPERM);
81 if (!cgroup_is_descendant(cgroup))
82 return ERR_PTR(-EPERM);
84 ns_cgroup = kzalloc(sizeof(*ns_cgroup), GFP_KERNEL);
86 return ERR_PTR(-ENOMEM);
87 spin_lock_init(&ns_cgroup->lock);
88 return &ns_cgroup->css;
91 static void ns_destroy(struct cgroup_subsys *ss,
92 struct cgroup *cgroup)
94 struct ns_cgroup *ns_cgroup;
96 ns_cgroup = cgroup_to_ns(cgroup);
100 struct cgroup_subsys ns_subsys = {
102 .can_attach = ns_can_attach,
104 .destroy = ns_destroy,
105 .subsys_id = ns_subsys_id,