5 * (C) 2007 Pavel Emelyanov <xemul@openvz.org>, OpenVZ, SWsoft Inc.
6 * (C) 2007 Sukadev Bhattiprolu <sukadev@us.ibm.com>, IBM
7 * Many thanks to Oleg Nesterov for comments and help
11 #include <linux/pid.h>
12 #include <linux/pid_namespace.h>
13 #include <linux/syscalls.h>
14 #include <linux/err.h>
15 #include <linux/acct.h>
16 #include <linux/slab.h>
17 #include <linux/proc_fs.h>
18 #include <linux/reboot.h>
19 #include <linux/export.h>
21 #define BITS_PER_PAGE (PAGE_SIZE*8)
26 struct kmem_cache *cachep;
27 struct list_head list;
30 static LIST_HEAD(pid_caches_lh);
31 static DEFINE_MUTEX(pid_caches_mutex);
32 static struct kmem_cache *pid_ns_cachep;
35 * creates the kmem cache to allocate pids from.
36 * @nr_ids: the number of numerical ids this pid will have to carry
39 static struct kmem_cache *create_pid_cachep(int nr_ids)
41 struct pid_cache *pcache;
42 struct kmem_cache *cachep;
44 mutex_lock(&pid_caches_mutex);
45 list_for_each_entry(pcache, &pid_caches_lh, list)
46 if (pcache->nr_ids == nr_ids)
49 pcache = kmalloc(sizeof(struct pid_cache), GFP_KERNEL);
53 snprintf(pcache->name, sizeof(pcache->name), "pid_%d", nr_ids);
54 cachep = kmem_cache_create(pcache->name,
55 sizeof(struct pid) + (nr_ids - 1) * sizeof(struct upid),
56 0, SLAB_HWCACHE_ALIGN, NULL);
60 pcache->nr_ids = nr_ids;
61 pcache->cachep = cachep;
62 list_add(&pcache->list, &pid_caches_lh);
64 mutex_unlock(&pid_caches_mutex);
65 return pcache->cachep;
70 mutex_unlock(&pid_caches_mutex);
74 static struct pid_namespace *create_pid_namespace(struct pid_namespace *parent_pid_ns)
76 struct pid_namespace *ns;
77 unsigned int level = parent_pid_ns->level + 1;
80 ns = kmem_cache_zalloc(pid_ns_cachep, GFP_KERNEL);
84 ns->pidmap[0].page = kzalloc(PAGE_SIZE, GFP_KERNEL);
85 if (!ns->pidmap[0].page)
88 ns->pid_cachep = create_pid_cachep(level + 1);
89 if (ns->pid_cachep == NULL)
94 ns->parent = get_pid_ns(parent_pid_ns);
96 set_bit(0, ns->pidmap[0].page);
97 atomic_set(&ns->pidmap[0].nr_free, BITS_PER_PAGE - 1);
99 for (i = 1; i < PIDMAP_ENTRIES; i++)
100 atomic_set(&ns->pidmap[i].nr_free, BITS_PER_PAGE);
102 err = pid_ns_prepare_proc(ns);
104 goto out_put_parent_pid_ns;
108 out_put_parent_pid_ns:
109 put_pid_ns(parent_pid_ns);
111 kfree(ns->pidmap[0].page);
113 kmem_cache_free(pid_ns_cachep, ns);
118 static void destroy_pid_namespace(struct pid_namespace *ns)
122 for (i = 0; i < PIDMAP_ENTRIES; i++)
123 kfree(ns->pidmap[i].page);
124 kmem_cache_free(pid_ns_cachep, ns);
127 struct pid_namespace *copy_pid_ns(unsigned long flags, struct pid_namespace *old_ns)
129 if (!(flags & CLONE_NEWPID))
130 return get_pid_ns(old_ns);
131 if (flags & (CLONE_THREAD|CLONE_PARENT))
132 return ERR_PTR(-EINVAL);
133 return create_pid_namespace(old_ns);
136 static void free_pid_ns(struct kref *kref)
138 struct pid_namespace *ns;
140 ns = container_of(kref, struct pid_namespace, kref);
141 destroy_pid_namespace(ns);
144 void put_pid_ns(struct pid_namespace *ns)
146 struct pid_namespace *parent;
148 while (ns != &init_pid_ns) {
150 if (!kref_put(&ns->kref, free_pid_ns))
155 EXPORT_SYMBOL_GPL(put_pid_ns);
157 void zap_pid_ns_processes(struct pid_namespace *pid_ns)
161 struct task_struct *task, *me = current;
163 /* Ignore SIGCHLD causing any terminated children to autoreap */
164 spin_lock_irq(&me->sighand->siglock);
165 me->sighand->action[SIGCHLD - 1].sa.sa_handler = SIG_IGN;
166 spin_unlock_irq(&me->sighand->siglock);
169 * The last thread in the cgroup-init thread group is terminating.
170 * Find remaining pid_ts in the namespace, signal and wait for them
173 * Note: This signals each threads in the namespace - even those that
174 * belong to the same thread group, To avoid this, we would have
175 * to walk the entire tasklist looking a processes in this
176 * namespace, but that could be unnecessarily expensive if the
177 * pid namespace has just a few processes. Or we need to
178 * maintain a tasklist for each pid namespace.
181 read_lock(&tasklist_lock);
182 nr = next_pidmap(pid_ns, 1);
186 task = pid_task(find_vpid(nr), PIDTYPE_PID);
187 if (task && !__fatal_signal_pending(task))
188 send_sig_info(SIGKILL, SEND_SIG_FORCED, task);
192 nr = next_pidmap(pid_ns, nr);
194 read_unlock(&tasklist_lock);
196 /* Firstly reap the EXIT_ZOMBIE children we may have. */
198 clear_thread_flag(TIF_SIGPENDING);
199 rc = sys_wait4(-1, NULL, __WALL, NULL);
200 } while (rc != -ECHILD);
203 * sys_wait4() above can't reap the TASK_DEAD children.
204 * Make sure they all go away, see __unhash_process().
207 bool need_wait = false;
209 read_lock(&tasklist_lock);
210 if (!list_empty(¤t->children)) {
211 __set_current_state(TASK_UNINTERRUPTIBLE);
214 read_unlock(&tasklist_lock);
222 current->signal->group_exit_code = pid_ns->reboot;
224 acct_exit_ns(pid_ns);
228 #ifdef CONFIG_CHECKPOINT_RESTORE
229 static int pid_ns_ctl_handler(struct ctl_table *table, int write,
230 void __user *buffer, size_t *lenp, loff_t *ppos)
232 struct ctl_table tmp = *table;
234 if (write && !capable(CAP_SYS_ADMIN))
238 * Writing directly to ns' last_pid field is OK, since this field
239 * is volatile in a living namespace anyway and a code writing to
240 * it should synchronize its usage with external means.
243 tmp.data = ¤t->nsproxy->pid_ns->last_pid;
244 return proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos);
249 static struct ctl_table pid_ns_ctl_table[] = {
251 .procname = "ns_last_pid",
252 .maxlen = sizeof(int),
253 .mode = 0666, /* permissions are checked in the handler */
254 .proc_handler = pid_ns_ctl_handler,
260 static struct ctl_path kern_path[] = { { .procname = "kernel", }, { } };
261 #endif /* CONFIG_CHECKPOINT_RESTORE */
263 int reboot_pid_ns(struct pid_namespace *pid_ns, int cmd)
265 if (pid_ns == &init_pid_ns)
269 case LINUX_REBOOT_CMD_RESTART2:
270 case LINUX_REBOOT_CMD_RESTART:
271 pid_ns->reboot = SIGHUP;
274 case LINUX_REBOOT_CMD_POWER_OFF:
275 case LINUX_REBOOT_CMD_HALT:
276 pid_ns->reboot = SIGINT;
282 read_lock(&tasklist_lock);
283 force_sig(SIGKILL, pid_ns->child_reaper);
284 read_unlock(&tasklist_lock);
292 static __init int pid_namespaces_init(void)
294 pid_ns_cachep = KMEM_CACHE(pid_namespace, SLAB_PANIC);
296 #ifdef CONFIG_CHECKPOINT_RESTORE
297 register_sysctl_paths(kern_path, pid_ns_ctl_table);
302 __initcall(pid_namespaces_init);