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/user_namespace.h>
14 #include <linux/syscalls.h>
15 #include <linux/err.h>
16 #include <linux/acct.h>
17 #include <linux/slab.h>
18 #include <linux/proc_ns.h>
19 #include <linux/reboot.h>
20 #include <linux/export.h>
25 struct kmem_cache *cachep;
26 struct list_head list;
29 static LIST_HEAD(pid_caches_lh);
30 static DEFINE_MUTEX(pid_caches_mutex);
31 static struct kmem_cache *pid_ns_cachep;
34 * creates the kmem cache to allocate pids from.
35 * @nr_ids: the number of numerical ids this pid will have to carry
38 static struct kmem_cache *create_pid_cachep(int nr_ids)
40 struct pid_cache *pcache;
41 struct kmem_cache *cachep;
43 mutex_lock(&pid_caches_mutex);
44 list_for_each_entry(pcache, &pid_caches_lh, list)
45 if (pcache->nr_ids == nr_ids)
48 pcache = kmalloc(sizeof(struct pid_cache), GFP_KERNEL);
52 snprintf(pcache->name, sizeof(pcache->name), "pid_%d", nr_ids);
53 cachep = kmem_cache_create(pcache->name,
54 sizeof(struct pid) + (nr_ids - 1) * sizeof(struct upid),
55 0, SLAB_HWCACHE_ALIGN, NULL);
59 pcache->nr_ids = nr_ids;
60 pcache->cachep = cachep;
61 list_add(&pcache->list, &pid_caches_lh);
63 mutex_unlock(&pid_caches_mutex);
64 return pcache->cachep;
69 mutex_unlock(&pid_caches_mutex);
73 static void proc_cleanup_work(struct work_struct *work)
75 struct pid_namespace *ns = container_of(work, struct pid_namespace, proc_work);
76 pid_ns_release_proc(ns);
79 /* MAX_PID_NS_LEVEL is needed for limiting size of 'struct pid' */
80 #define MAX_PID_NS_LEVEL 32
82 static struct pid_namespace *create_pid_namespace(struct user_namespace *user_ns,
83 struct pid_namespace *parent_pid_ns)
85 struct pid_namespace *ns;
86 unsigned int level = parent_pid_ns->level + 1;
90 if (level > MAX_PID_NS_LEVEL) {
96 ns = kmem_cache_zalloc(pid_ns_cachep, GFP_KERNEL);
100 ns->pidmap[0].page = kzalloc(PAGE_SIZE, GFP_KERNEL);
101 if (!ns->pidmap[0].page)
104 ns->pid_cachep = create_pid_cachep(level + 1);
105 if (ns->pid_cachep == NULL)
108 err = ns_alloc_inum(&ns->ns);
111 ns->ns.ops = &pidns_operations;
113 kref_init(&ns->kref);
115 ns->parent = get_pid_ns(parent_pid_ns);
116 ns->user_ns = get_user_ns(user_ns);
117 ns->nr_hashed = PIDNS_HASH_ADDING;
118 INIT_WORK(&ns->proc_work, proc_cleanup_work);
120 set_bit(0, ns->pidmap[0].page);
121 atomic_set(&ns->pidmap[0].nr_free, BITS_PER_PAGE - 1);
123 for (i = 1; i < PIDMAP_ENTRIES; i++)
124 atomic_set(&ns->pidmap[i].nr_free, BITS_PER_PAGE);
129 kfree(ns->pidmap[0].page);
131 kmem_cache_free(pid_ns_cachep, ns);
136 static void delayed_free_pidns(struct rcu_head *p)
138 kmem_cache_free(pid_ns_cachep,
139 container_of(p, struct pid_namespace, rcu));
142 static void destroy_pid_namespace(struct pid_namespace *ns)
146 ns_free_inum(&ns->ns);
147 for (i = 0; i < PIDMAP_ENTRIES; i++)
148 kfree(ns->pidmap[i].page);
149 put_user_ns(ns->user_ns);
150 call_rcu(&ns->rcu, delayed_free_pidns);
153 struct pid_namespace *copy_pid_ns(unsigned long flags,
154 struct user_namespace *user_ns, struct pid_namespace *old_ns)
156 if (!(flags & CLONE_NEWPID))
157 return get_pid_ns(old_ns);
158 if (task_active_pid_ns(current) != old_ns)
159 return ERR_PTR(-EINVAL);
160 return create_pid_namespace(user_ns, old_ns);
163 static void free_pid_ns(struct kref *kref)
165 struct pid_namespace *ns;
167 ns = container_of(kref, struct pid_namespace, kref);
168 destroy_pid_namespace(ns);
171 void put_pid_ns(struct pid_namespace *ns)
173 struct pid_namespace *parent;
175 while (ns != &init_pid_ns) {
177 if (!kref_put(&ns->kref, free_pid_ns))
182 EXPORT_SYMBOL_GPL(put_pid_ns);
184 void zap_pid_ns_processes(struct pid_namespace *pid_ns)
188 struct task_struct *task, *me = current;
189 int init_pids = thread_group_leader(me) ? 1 : 2;
191 /* Don't allow any more processes into the pid namespace */
192 disable_pid_allocation(pid_ns);
194 /* Ignore SIGCHLD causing any terminated children to autoreap */
195 spin_lock_irq(&me->sighand->siglock);
196 me->sighand->action[SIGCHLD - 1].sa.sa_handler = SIG_IGN;
197 spin_unlock_irq(&me->sighand->siglock);
200 * The last thread in the cgroup-init thread group is terminating.
201 * Find remaining pid_ts in the namespace, signal and wait for them
204 * Note: This signals each threads in the namespace - even those that
205 * belong to the same thread group, To avoid this, we would have
206 * to walk the entire tasklist looking a processes in this
207 * namespace, but that could be unnecessarily expensive if the
208 * pid namespace has just a few processes. Or we need to
209 * maintain a tasklist for each pid namespace.
212 read_lock(&tasklist_lock);
213 nr = next_pidmap(pid_ns, 1);
217 task = pid_task(find_vpid(nr), PIDTYPE_PID);
218 if (task && !__fatal_signal_pending(task))
219 send_sig_info(SIGKILL, SEND_SIG_FORCED, task);
223 nr = next_pidmap(pid_ns, nr);
225 read_unlock(&tasklist_lock);
227 /* Firstly reap the EXIT_ZOMBIE children we may have. */
229 clear_thread_flag(TIF_SIGPENDING);
230 rc = sys_wait4(-1, NULL, __WALL, NULL);
231 } while (rc != -ECHILD);
234 * sys_wait4() above can't reap the TASK_DEAD children.
235 * Make sure they all go away, see free_pid().
238 set_current_state(TASK_UNINTERRUPTIBLE);
239 if (pid_ns->nr_hashed == init_pids)
243 __set_current_state(TASK_RUNNING);
246 current->signal->group_exit_code = pid_ns->reboot;
248 acct_exit_ns(pid_ns);
252 #ifdef CONFIG_CHECKPOINT_RESTORE
253 static int pid_ns_ctl_handler(struct ctl_table *table, int write,
254 void __user *buffer, size_t *lenp, loff_t *ppos)
256 struct pid_namespace *pid_ns = task_active_pid_ns(current);
257 struct ctl_table tmp = *table;
259 if (write && !ns_capable(pid_ns->user_ns, CAP_SYS_ADMIN))
263 * Writing directly to ns' last_pid field is OK, since this field
264 * is volatile in a living namespace anyway and a code writing to
265 * it should synchronize its usage with external means.
268 tmp.data = &pid_ns->last_pid;
269 return proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos);
274 static struct ctl_table pid_ns_ctl_table[] = {
276 .procname = "ns_last_pid",
277 .maxlen = sizeof(int),
278 .mode = 0666, /* permissions are checked in the handler */
279 .proc_handler = pid_ns_ctl_handler,
285 static struct ctl_path kern_path[] = { { .procname = "kernel", }, { } };
286 #endif /* CONFIG_CHECKPOINT_RESTORE */
288 int reboot_pid_ns(struct pid_namespace *pid_ns, int cmd)
290 if (pid_ns == &init_pid_ns)
294 case LINUX_REBOOT_CMD_RESTART2:
295 case LINUX_REBOOT_CMD_RESTART:
296 pid_ns->reboot = SIGHUP;
299 case LINUX_REBOOT_CMD_POWER_OFF:
300 case LINUX_REBOOT_CMD_HALT:
301 pid_ns->reboot = SIGINT;
307 read_lock(&tasklist_lock);
308 force_sig(SIGKILL, pid_ns->child_reaper);
309 read_unlock(&tasklist_lock);
317 static inline struct pid_namespace *to_pid_ns(struct ns_common *ns)
319 return container_of(ns, struct pid_namespace, ns);
322 static struct ns_common *pidns_get(struct task_struct *task)
324 struct pid_namespace *ns;
327 ns = task_active_pid_ns(task);
332 return ns ? &ns->ns : NULL;
335 static void pidns_put(struct ns_common *ns)
337 put_pid_ns(to_pid_ns(ns));
340 static int pidns_install(struct nsproxy *nsproxy, struct ns_common *ns)
342 struct pid_namespace *active = task_active_pid_ns(current);
343 struct pid_namespace *ancestor, *new = to_pid_ns(ns);
345 if (!ns_capable(new->user_ns, CAP_SYS_ADMIN) ||
346 !ns_capable(current_user_ns(), CAP_SYS_ADMIN))
350 * Only allow entering the current active pid namespace
351 * or a child of the current active pid namespace.
353 * This is required for fork to return a usable pid value and
354 * this maintains the property that processes and their
355 * children can not escape their current pid namespace.
357 if (new->level < active->level)
361 while (ancestor->level > active->level)
362 ancestor = ancestor->parent;
363 if (ancestor != active)
366 put_pid_ns(nsproxy->pid_ns_for_children);
367 nsproxy->pid_ns_for_children = get_pid_ns(new);
371 const struct proc_ns_operations pidns_operations = {
373 .type = CLONE_NEWPID,
376 .install = pidns_install,
379 static __init int pid_namespaces_init(void)
381 pid_ns_cachep = KMEM_CACHE(pid_namespace, SLAB_PANIC);
383 #ifdef CONFIG_CHECKPOINT_RESTORE
384 register_sysctl_paths(kern_path, pid_ns_ctl_table);
389 __initcall(pid_namespaces_init);