ftrace: Add self-tests for multiple function trace users
[linux-2.6.git] / kernel / ns_cgroup.c
1 /*
2  * ns_cgroup.c - namespace cgroup subsystem
3  *
4  * Copyright 2006, 2007 IBM Corp
5  */
6
7 #include <linux/module.h>
8 #include <linux/cgroup.h>
9 #include <linux/fs.h>
10 #include <linux/proc_fs.h>
11 #include <linux/slab.h>
12 #include <linux/nsproxy.h>
13
14 struct ns_cgroup {
15         struct cgroup_subsys_state css;
16 };
17
18 struct cgroup_subsys ns_subsys;
19
20 static inline struct ns_cgroup *cgroup_to_ns(
21                 struct cgroup *cgroup)
22 {
23         return container_of(cgroup_subsys_state(cgroup, ns_subsys_id),
24                             struct ns_cgroup, css);
25 }
26
27 int ns_cgroup_clone(struct task_struct *task, struct pid *pid)
28 {
29         char name[PROC_NUMBUF];
30
31         snprintf(name, PROC_NUMBUF, "%d", pid_vnr(pid));
32         return cgroup_clone(task, &ns_subsys, name);
33 }
34
35 /*
36  * Rules:
37  *   1. you can only enter a cgroup which is a descendant of your current
38  *     cgroup
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)
44  */
45 static int ns_can_attach(struct cgroup_subsys *ss, struct cgroup *new_cgroup,
46                          struct task_struct *task, bool threadgroup)
47 {
48         if (current != task) {
49                 if (!capable(CAP_SYS_ADMIN))
50                         return -EPERM;
51
52                 if (!cgroup_is_descendant(new_cgroup, current))
53                         return -EPERM;
54         }
55
56         if (!cgroup_is_descendant(new_cgroup, task))
57                 return -EPERM;
58
59         if (threadgroup) {
60                 struct task_struct *c;
61                 rcu_read_lock();
62                 list_for_each_entry_rcu(c, &task->thread_group, thread_group) {
63                         if (!cgroup_is_descendant(new_cgroup, c)) {
64                                 rcu_read_unlock();
65                                 return -EPERM;
66                         }
67                 }
68                 rcu_read_unlock();
69         }
70
71         return 0;
72 }
73
74 /*
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
78  */
79 static struct cgroup_subsys_state *ns_create(struct cgroup_subsys *ss,
80                                                 struct cgroup *cgroup)
81 {
82         struct ns_cgroup *ns_cgroup;
83
84         if (!capable(CAP_SYS_ADMIN))
85                 return ERR_PTR(-EPERM);
86         if (!cgroup_is_descendant(cgroup, current))
87                 return ERR_PTR(-EPERM);
88         if (test_bit(CGRP_CLONE_CHILDREN, &cgroup->flags)) {
89                 printk("ns_cgroup can't be created with parent "
90                        "'clone_children' set.\n");
91                 return ERR_PTR(-EINVAL);
92         }
93
94         printk_once("ns_cgroup deprecated: consider using the "
95                     "'clone_children' flag without the ns_cgroup.\n");
96
97         ns_cgroup = kzalloc(sizeof(*ns_cgroup), GFP_KERNEL);
98         if (!ns_cgroup)
99                 return ERR_PTR(-ENOMEM);
100         return &ns_cgroup->css;
101 }
102
103 static void ns_destroy(struct cgroup_subsys *ss,
104                         struct cgroup *cgroup)
105 {
106         struct ns_cgroup *ns_cgroup;
107
108         ns_cgroup = cgroup_to_ns(cgroup);
109         kfree(ns_cgroup);
110 }
111
112 struct cgroup_subsys ns_subsys = {
113         .name = "ns",
114         .can_attach = ns_can_attach,
115         .create = ns_create,
116         .destroy  = ns_destroy,
117         .subsys_id = ns_subsys_id,
118 };