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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/cred.h>
16#include <linux/err.h>
17#include <linux/acct.h>
18#include <linux/slab.h>
19#include <linux/proc_ns.h>
20#include <linux/reboot.h>
21#include <linux/export.h>
22#include <linux/sched/task.h>
23#include <linux/sched/signal.h>
24
25struct pid_cache {
26 int nr_ids;
27 char name[16];
28 struct kmem_cache *cachep;
29 struct list_head list;
30};
31
32static LIST_HEAD(pid_caches_lh);
33static DEFINE_MUTEX(pid_caches_mutex);
34static struct kmem_cache *pid_ns_cachep;
35
36
37
38
39
40
41static struct kmem_cache *create_pid_cachep(int nr_ids)
42{
43 struct pid_cache *pcache;
44 struct kmem_cache *cachep;
45
46 mutex_lock(&pid_caches_mutex);
47 list_for_each_entry(pcache, &pid_caches_lh, list)
48 if (pcache->nr_ids == nr_ids)
49 goto out;
50
51 pcache = kmalloc(sizeof(struct pid_cache), GFP_KERNEL);
52 if (pcache == NULL)
53 goto err_alloc;
54
55 snprintf(pcache->name, sizeof(pcache->name), "pid_%d", nr_ids);
56 cachep = kmem_cache_create(pcache->name,
57 sizeof(struct pid) + (nr_ids - 1) * sizeof(struct upid),
58 0, SLAB_HWCACHE_ALIGN, NULL);
59 if (cachep == NULL)
60 goto err_cachep;
61
62 pcache->nr_ids = nr_ids;
63 pcache->cachep = cachep;
64 list_add(&pcache->list, &pid_caches_lh);
65out:
66 mutex_unlock(&pid_caches_mutex);
67 return pcache->cachep;
68
69err_cachep:
70 kfree(pcache);
71err_alloc:
72 mutex_unlock(&pid_caches_mutex);
73 return NULL;
74}
75
76static void proc_cleanup_work(struct work_struct *work)
77{
78 struct pid_namespace *ns = container_of(work, struct pid_namespace, proc_work);
79 pid_ns_release_proc(ns);
80}
81
82
83#define MAX_PID_NS_LEVEL 32
84
85static struct ucounts *inc_pid_namespaces(struct user_namespace *ns)
86{
87 return inc_ucount(ns, current_euid(), UCOUNT_PID_NAMESPACES);
88}
89
90static void dec_pid_namespaces(struct ucounts *ucounts)
91{
92 dec_ucount(ucounts, UCOUNT_PID_NAMESPACES);
93}
94
95static struct pid_namespace *create_pid_namespace(struct user_namespace *user_ns,
96 struct pid_namespace *parent_pid_ns)
97{
98 struct pid_namespace *ns;
99 unsigned int level = parent_pid_ns->level + 1;
100 struct ucounts *ucounts;
101 int i;
102 int err;
103
104 err = -ENOSPC;
105 if (level > MAX_PID_NS_LEVEL)
106 goto out;
107 ucounts = inc_pid_namespaces(user_ns);
108 if (!ucounts)
109 goto out;
110
111 err = -ENOMEM;
112 ns = kmem_cache_zalloc(pid_ns_cachep, GFP_KERNEL);
113 if (ns == NULL)
114 goto out_dec;
115
116 ns->pidmap[0].page = kzalloc(PAGE_SIZE, GFP_KERNEL);
117 if (!ns->pidmap[0].page)
118 goto out_free;
119
120 ns->pid_cachep = create_pid_cachep(level + 1);
121 if (ns->pid_cachep == NULL)
122 goto out_free_map;
123
124 err = ns_alloc_inum(&ns->ns);
125 if (err)
126 goto out_free_map;
127 ns->ns.ops = &pidns_operations;
128
129 kref_init(&ns->kref);
130 ns->level = level;
131 ns->parent = get_pid_ns(parent_pid_ns);
132 ns->user_ns = get_user_ns(user_ns);
133 ns->ucounts = ucounts;
134 ns->nr_hashed = PIDNS_HASH_ADDING;
135 INIT_WORK(&ns->proc_work, proc_cleanup_work);
136
137 set_bit(0, ns->pidmap[0].page);
138 atomic_set(&ns->pidmap[0].nr_free, BITS_PER_PAGE - 1);
139
140 for (i = 1; i < PIDMAP_ENTRIES; i++)
141 atomic_set(&ns->pidmap[i].nr_free, BITS_PER_PAGE);
142
143 return ns;
144
145out_free_map:
146 kfree(ns->pidmap[0].page);
147out_free:
148 kmem_cache_free(pid_ns_cachep, ns);
149out_dec:
150 dec_pid_namespaces(ucounts);
151out:
152 return ERR_PTR(err);
153}
154
155static void delayed_free_pidns(struct rcu_head *p)
156{
157 struct pid_namespace *ns = container_of(p, struct pid_namespace, rcu);
158
159 dec_pid_namespaces(ns->ucounts);
160 put_user_ns(ns->user_ns);
161
162 kmem_cache_free(pid_ns_cachep, ns);
163}
164
165static void destroy_pid_namespace(struct pid_namespace *ns)
166{
167 int i;
168
169 ns_free_inum(&ns->ns);
170 for (i = 0; i < PIDMAP_ENTRIES; i++)
171 kfree(ns->pidmap[i].page);
172 call_rcu(&ns->rcu, delayed_free_pidns);
173}
174
175struct pid_namespace *copy_pid_ns(unsigned long flags,
176 struct user_namespace *user_ns, struct pid_namespace *old_ns)
177{
178 if (!(flags & CLONE_NEWPID))
179 return get_pid_ns(old_ns);
180 if (task_active_pid_ns(current) != old_ns)
181 return ERR_PTR(-EINVAL);
182 return create_pid_namespace(user_ns, old_ns);
183}
184
185static void free_pid_ns(struct kref *kref)
186{
187 struct pid_namespace *ns;
188
189 ns = container_of(kref, struct pid_namespace, kref);
190 destroy_pid_namespace(ns);
191}
192
193void put_pid_ns(struct pid_namespace *ns)
194{
195 struct pid_namespace *parent;
196
197 while (ns != &init_pid_ns) {
198 parent = ns->parent;
199 if (!kref_put(&ns->kref, free_pid_ns))
200 break;
201 ns = parent;
202 }
203}
204EXPORT_SYMBOL_GPL(put_pid_ns);
205
206void zap_pid_ns_processes(struct pid_namespace *pid_ns)
207{
208 int nr;
209 int rc;
210 struct task_struct *task, *me = current;
211 int init_pids = thread_group_leader(me) ? 1 : 2;
212
213
214 disable_pid_allocation(pid_ns);
215
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220
221 spin_lock_irq(&me->sighand->siglock);
222 me->sighand->action[SIGCHLD - 1].sa.sa_handler = SIG_IGN;
223 spin_unlock_irq(&me->sighand->siglock);
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238 read_lock(&tasklist_lock);
239 nr = next_pidmap(pid_ns, 1);
240 while (nr > 0) {
241 rcu_read_lock();
242
243 task = pid_task(find_vpid(nr), PIDTYPE_PID);
244 if (task && !__fatal_signal_pending(task))
245 send_sig_info(SIGKILL, SEND_SIG_FORCED, task);
246
247 rcu_read_unlock();
248
249 nr = next_pidmap(pid_ns, nr);
250 }
251 read_unlock(&tasklist_lock);
252
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256
257
258 do {
259 clear_thread_flag(TIF_SIGPENDING);
260 rc = sys_wait4(-1, NULL, __WALL, NULL);
261 } while (rc != -ECHILD);
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279 for (;;) {
280 set_current_state(TASK_UNINTERRUPTIBLE);
281 if (pid_ns->nr_hashed == init_pids)
282 break;
283 schedule();
284 }
285 __set_current_state(TASK_RUNNING);
286
287 if (pid_ns->reboot)
288 current->signal->group_exit_code = pid_ns->reboot;
289
290 acct_exit_ns(pid_ns);
291 return;
292}
293
294#ifdef CONFIG_CHECKPOINT_RESTORE
295static int pid_ns_ctl_handler(struct ctl_table *table, int write,
296 void __user *buffer, size_t *lenp, loff_t *ppos)
297{
298 struct pid_namespace *pid_ns = task_active_pid_ns(current);
299 struct ctl_table tmp = *table;
300
301 if (write && !ns_capable(pid_ns->user_ns, CAP_SYS_ADMIN))
302 return -EPERM;
303
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310 tmp.data = &pid_ns->last_pid;
311 return proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos);
312}
313
314extern int pid_max;
315static int zero = 0;
316static struct ctl_table pid_ns_ctl_table[] = {
317 {
318 .procname = "ns_last_pid",
319 .maxlen = sizeof(int),
320 .mode = 0666,
321 .proc_handler = pid_ns_ctl_handler,
322 .extra1 = &zero,
323 .extra2 = &pid_max,
324 },
325 { }
326};
327static struct ctl_path kern_path[] = { { .procname = "kernel", }, { } };
328#endif
329
330int reboot_pid_ns(struct pid_namespace *pid_ns, int cmd)
331{
332 if (pid_ns == &init_pid_ns)
333 return 0;
334
335 switch (cmd) {
336 case LINUX_REBOOT_CMD_RESTART2:
337 case LINUX_REBOOT_CMD_RESTART:
338 pid_ns->reboot = SIGHUP;
339 break;
340
341 case LINUX_REBOOT_CMD_POWER_OFF:
342 case LINUX_REBOOT_CMD_HALT:
343 pid_ns->reboot = SIGINT;
344 break;
345 default:
346 return -EINVAL;
347 }
348
349 read_lock(&tasklist_lock);
350 force_sig(SIGKILL, pid_ns->child_reaper);
351 read_unlock(&tasklist_lock);
352
353 do_exit(0);
354
355
356 return 0;
357}
358
359static inline struct pid_namespace *to_pid_ns(struct ns_common *ns)
360{
361 return container_of(ns, struct pid_namespace, ns);
362}
363
364static struct ns_common *pidns_get(struct task_struct *task)
365{
366 struct pid_namespace *ns;
367
368 rcu_read_lock();
369 ns = task_active_pid_ns(task);
370 if (ns)
371 get_pid_ns(ns);
372 rcu_read_unlock();
373
374 return ns ? &ns->ns : NULL;
375}
376
377static void pidns_put(struct ns_common *ns)
378{
379 put_pid_ns(to_pid_ns(ns));
380}
381
382static int pidns_install(struct nsproxy *nsproxy, struct ns_common *ns)
383{
384 struct pid_namespace *active = task_active_pid_ns(current);
385 struct pid_namespace *ancestor, *new = to_pid_ns(ns);
386
387 if (!ns_capable(new->user_ns, CAP_SYS_ADMIN) ||
388 !ns_capable(current_user_ns(), CAP_SYS_ADMIN))
389 return -EPERM;
390
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399 if (new->level < active->level)
400 return -EINVAL;
401
402 ancestor = new;
403 while (ancestor->level > active->level)
404 ancestor = ancestor->parent;
405 if (ancestor != active)
406 return -EINVAL;
407
408 put_pid_ns(nsproxy->pid_ns_for_children);
409 nsproxy->pid_ns_for_children = get_pid_ns(new);
410 return 0;
411}
412
413static struct ns_common *pidns_get_parent(struct ns_common *ns)
414{
415 struct pid_namespace *active = task_active_pid_ns(current);
416 struct pid_namespace *pid_ns, *p;
417
418
419 pid_ns = p = to_pid_ns(ns)->parent;
420 for (;;) {
421 if (!p)
422 return ERR_PTR(-EPERM);
423 if (p == active)
424 break;
425 p = p->parent;
426 }
427
428 return &get_pid_ns(pid_ns)->ns;
429}
430
431static struct user_namespace *pidns_owner(struct ns_common *ns)
432{
433 return to_pid_ns(ns)->user_ns;
434}
435
436const struct proc_ns_operations pidns_operations = {
437 .name = "pid",
438 .type = CLONE_NEWPID,
439 .get = pidns_get,
440 .put = pidns_put,
441 .install = pidns_install,
442 .owner = pidns_owner,
443 .get_parent = pidns_get_parent,
444};
445
446static __init int pid_namespaces_init(void)
447{
448 pid_ns_cachep = KMEM_CACHE(pid_namespace, SLAB_PANIC);
449
450#ifdef CONFIG_CHECKPOINT_RESTORE
451 register_sysctl_paths(kern_path, pid_ns_ctl_table);
452#endif
453 return 0;
454}
455
456__initcall(pid_namespaces_init);
457