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 = proc_alloc_inum(&ns->proc_inum);
112 kref_init(&ns->kref);
114 ns->parent = get_pid_ns(parent_pid_ns);
115 ns->user_ns = get_user_ns(user_ns);
116 ns->nr_hashed = PIDNS_HASH_ADDING;
117 INIT_WORK(&ns->proc_work, proc_cleanup_work);
119 set_bit(0, ns->pidmap[0].page);
120 atomic_set(&ns->pidmap[0].nr_free, BITS_PER_PAGE - 1);
122 for (i = 1; i < PIDMAP_ENTRIES; i++)
123 atomic_set(&ns->pidmap[i].nr_free, BITS_PER_PAGE);
128 kfree(ns->pidmap[0].page);
130 kmem_cache_free(pid_ns_cachep, ns);
135 static void delayed_free_pidns(struct rcu_head *p)
137 kmem_cache_free(pid_ns_cachep,
138 container_of(p, struct pid_namespace, rcu));
141 static void destroy_pid_namespace(struct pid_namespace *ns)
145 proc_free_inum(ns->proc_inum);
146 for (i = 0; i < PIDMAP_ENTRIES; i++)
147 kfree(ns->pidmap[i].page);
148 put_user_ns(ns->user_ns);
149 call_rcu(&ns->rcu, delayed_free_pidns);
152 struct pid_namespace *copy_pid_ns(unsigned long flags,
153 struct user_namespace *user_ns, struct pid_namespace *old_ns)
155 if (!(flags & CLONE_NEWPID))
156 return get_pid_ns(old_ns);
157 if (task_active_pid_ns(current) != old_ns)
158 return ERR_PTR(-EINVAL);
159 return create_pid_namespace(user_ns, old_ns);
162 static void free_pid_ns(struct kref *kref)
164 struct pid_namespace *ns;
166 ns = container_of(kref, struct pid_namespace, kref);
167 destroy_pid_namespace(ns);
170 void put_pid_ns(struct pid_namespace *ns)
172 struct pid_namespace *parent;
174 while (ns != &init_pid_ns) {
176 if (!kref_put(&ns->kref, free_pid_ns))
181 EXPORT_SYMBOL_GPL(put_pid_ns);
183 void zap_pid_ns_processes(struct pid_namespace *pid_ns)
187 struct task_struct *task, *me = current;
188 int init_pids = thread_group_leader(me) ? 1 : 2;
190 /* Don't allow any more processes into the pid namespace */
191 disable_pid_allocation(pid_ns);
193 /* Ignore SIGCHLD causing any terminated children to autoreap */
194 spin_lock_irq(&me->sighand->siglock);
195 me->sighand->action[SIGCHLD - 1].sa.sa_handler = SIG_IGN;
196 spin_unlock_irq(&me->sighand->siglock);
199 * The last thread in the cgroup-init thread group is terminating.
200 * Find remaining pid_ts in the namespace, signal and wait for them
203 * Note: This signals each threads in the namespace - even those that
204 * belong to the same thread group, To avoid this, we would have
205 * to walk the entire tasklist looking a processes in this
206 * namespace, but that could be unnecessarily expensive if the
207 * pid namespace has just a few processes. Or we need to
208 * maintain a tasklist for each pid namespace.
211 read_lock(&tasklist_lock);
212 nr = next_pidmap(pid_ns, 1);
216 task = pid_task(find_vpid(nr), PIDTYPE_PID);
217 if (task && !__fatal_signal_pending(task))
218 send_sig_info(SIGKILL, SEND_SIG_FORCED, task);
222 nr = next_pidmap(pid_ns, nr);
224 read_unlock(&tasklist_lock);
226 /* Firstly reap the EXIT_ZOMBIE children we may have. */
228 clear_thread_flag(TIF_SIGPENDING);
229 rc = sys_wait4(-1, NULL, __WALL, NULL);
230 } while (rc != -ECHILD);
233 * sys_wait4() above can't reap the TASK_DEAD children.
234 * Make sure they all go away, see free_pid().
237 set_current_state(TASK_UNINTERRUPTIBLE);
238 if (pid_ns->nr_hashed == init_pids)
242 __set_current_state(TASK_RUNNING);
245 current->signal->group_exit_code = pid_ns->reboot;
247 acct_exit_ns(pid_ns);
251 #ifdef CONFIG_CHECKPOINT_RESTORE
252 static int pid_ns_ctl_handler(struct ctl_table *table, int write,
253 void __user *buffer, size_t *lenp, loff_t *ppos)
255 struct pid_namespace *pid_ns = task_active_pid_ns(current);
256 struct ctl_table tmp = *table;
258 if (write && !ns_capable(pid_ns->user_ns, CAP_SYS_ADMIN))
262 * Writing directly to ns' last_pid field is OK, since this field
263 * is volatile in a living namespace anyway and a code writing to
264 * it should synchronize its usage with external means.
267 tmp.data = &pid_ns->last_pid;
268 return proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos);
273 static struct ctl_table pid_ns_ctl_table[] = {
275 .procname = "ns_last_pid",
276 .maxlen = sizeof(int),
277 .mode = 0666, /* permissions are checked in the handler */
278 .proc_handler = pid_ns_ctl_handler,
284 static struct ctl_path kern_path[] = { { .procname = "kernel", }, { } };
285 #endif /* CONFIG_CHECKPOINT_RESTORE */
287 int reboot_pid_ns(struct pid_namespace *pid_ns, int cmd)
289 if (pid_ns == &init_pid_ns)
293 case LINUX_REBOOT_CMD_RESTART2:
294 case LINUX_REBOOT_CMD_RESTART:
295 pid_ns->reboot = SIGHUP;
298 case LINUX_REBOOT_CMD_POWER_OFF:
299 case LINUX_REBOOT_CMD_HALT:
300 pid_ns->reboot = SIGINT;
306 read_lock(&tasklist_lock);
307 force_sig(SIGKILL, pid_ns->child_reaper);
308 read_unlock(&tasklist_lock);
316 static void *pidns_get(struct task_struct *task)
318 struct pid_namespace *ns;
321 ns = task_active_pid_ns(task);
329 static void pidns_put(void *ns)
334 static int pidns_install(struct nsproxy *nsproxy, void *ns)
336 struct pid_namespace *active = task_active_pid_ns(current);
337 struct pid_namespace *ancestor, *new = ns;
339 if (!ns_capable(new->user_ns, CAP_SYS_ADMIN) ||
340 !ns_capable(current_user_ns(), CAP_SYS_ADMIN))
344 * Only allow entering the current active pid namespace
345 * or a child of the current active pid namespace.
347 * This is required for fork to return a usable pid value and
348 * this maintains the property that processes and their
349 * children can not escape their current pid namespace.
351 if (new->level < active->level)
355 while (ancestor->level > active->level)
356 ancestor = ancestor->parent;
357 if (ancestor != active)
360 put_pid_ns(nsproxy->pid_ns_for_children);
361 nsproxy->pid_ns_for_children = get_pid_ns(new);
365 static unsigned int pidns_inum(void *ns)
367 struct pid_namespace *pid_ns = ns;
368 return pid_ns->proc_inum;
371 const struct proc_ns_operations pidns_operations = {
373 .type = CLONE_NEWPID,
376 .install = pidns_install,
380 static __init int pid_namespaces_init(void)
382 pid_ns_cachep = KMEM_CACHE(pid_namespace, SLAB_PANIC);
384 #ifdef CONFIG_CHECKPOINT_RESTORE
385 register_sysctl_paths(kern_path, pid_ns_ctl_table);
390 __initcall(pid_namespaces_init);