Commit | Line | Data |
---|---|---|
74bd59bb PE |
1 | /* |
2 | * Pid namespaces | |
3 | * | |
4 | * Authors: | |
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 | |
8 | * | |
9 | */ | |
10 | ||
11 | #include <linux/pid.h> | |
12 | #include <linux/pid_namespace.h> | |
49f4d8b9 | 13 | #include <linux/user_namespace.h> |
74bd59bb PE |
14 | #include <linux/syscalls.h> |
15 | #include <linux/err.h> | |
0b6b030f | 16 | #include <linux/acct.h> |
5a0e3ad6 | 17 | #include <linux/slab.h> |
0bb80f24 | 18 | #include <linux/proc_ns.h> |
cf3f8921 | 19 | #include <linux/reboot.h> |
523a6a94 | 20 | #include <linux/export.h> |
74bd59bb | 21 | |
74bd59bb PE |
22 | struct pid_cache { |
23 | int nr_ids; | |
24 | char name[16]; | |
25 | struct kmem_cache *cachep; | |
26 | struct list_head list; | |
27 | }; | |
28 | ||
29 | static LIST_HEAD(pid_caches_lh); | |
30 | static DEFINE_MUTEX(pid_caches_mutex); | |
31 | static struct kmem_cache *pid_ns_cachep; | |
32 | ||
33 | /* | |
34 | * creates the kmem cache to allocate pids from. | |
35 | * @nr_ids: the number of numerical ids this pid will have to carry | |
36 | */ | |
37 | ||
38 | static struct kmem_cache *create_pid_cachep(int nr_ids) | |
39 | { | |
40 | struct pid_cache *pcache; | |
41 | struct kmem_cache *cachep; | |
42 | ||
43 | mutex_lock(&pid_caches_mutex); | |
44 | list_for_each_entry(pcache, &pid_caches_lh, list) | |
45 | if (pcache->nr_ids == nr_ids) | |
46 | goto out; | |
47 | ||
48 | pcache = kmalloc(sizeof(struct pid_cache), GFP_KERNEL); | |
49 | if (pcache == NULL) | |
50 | goto err_alloc; | |
51 | ||
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); | |
56 | if (cachep == NULL) | |
57 | goto err_cachep; | |
58 | ||
59 | pcache->nr_ids = nr_ids; | |
60 | pcache->cachep = cachep; | |
61 | list_add(&pcache->list, &pid_caches_lh); | |
62 | out: | |
63 | mutex_unlock(&pid_caches_mutex); | |
64 | return pcache->cachep; | |
65 | ||
66 | err_cachep: | |
67 | kfree(pcache); | |
68 | err_alloc: | |
69 | mutex_unlock(&pid_caches_mutex); | |
70 | return NULL; | |
71 | } | |
72 | ||
0a01f2cc EB |
73 | static void proc_cleanup_work(struct work_struct *work) |
74 | { | |
75 | struct pid_namespace *ns = container_of(work, struct pid_namespace, proc_work); | |
76 | pid_ns_release_proc(ns); | |
77 | } | |
78 | ||
f2302505 AV |
79 | /* MAX_PID_NS_LEVEL is needed for limiting size of 'struct pid' */ |
80 | #define MAX_PID_NS_LEVEL 32 | |
81 | ||
f333c700 EB |
82 | static struct ucounts *inc_pid_namespaces(struct user_namespace *ns) |
83 | { | |
84 | return inc_ucount(ns, current_euid(), UCOUNT_PID_NAMESPACES); | |
85 | } | |
86 | ||
87 | static void dec_pid_namespaces(struct ucounts *ucounts) | |
88 | { | |
89 | dec_ucount(ucounts, UCOUNT_PID_NAMESPACES); | |
90 | } | |
91 | ||
49f4d8b9 EB |
92 | static struct pid_namespace *create_pid_namespace(struct user_namespace *user_ns, |
93 | struct pid_namespace *parent_pid_ns) | |
74bd59bb PE |
94 | { |
95 | struct pid_namespace *ns; | |
ed469a63 | 96 | unsigned int level = parent_pid_ns->level + 1; |
f333c700 | 97 | struct ucounts *ucounts; |
f2302505 AV |
98 | int i; |
99 | int err; | |
100 | ||
df75e774 | 101 | err = -ENOSPC; |
f333c700 EB |
102 | if (level > MAX_PID_NS_LEVEL) |
103 | goto out; | |
104 | ucounts = inc_pid_namespaces(user_ns); | |
105 | if (!ucounts) | |
f2302505 | 106 | goto out; |
74bd59bb | 107 | |
f2302505 | 108 | err = -ENOMEM; |
84406c15 | 109 | ns = kmem_cache_zalloc(pid_ns_cachep, GFP_KERNEL); |
74bd59bb | 110 | if (ns == NULL) |
f333c700 | 111 | goto out_dec; |
74bd59bb PE |
112 | |
113 | ns->pidmap[0].page = kzalloc(PAGE_SIZE, GFP_KERNEL); | |
114 | if (!ns->pidmap[0].page) | |
115 | goto out_free; | |
116 | ||
117 | ns->pid_cachep = create_pid_cachep(level + 1); | |
118 | if (ns->pid_cachep == NULL) | |
119 | goto out_free_map; | |
120 | ||
6344c433 | 121 | err = ns_alloc_inum(&ns->ns); |
98f842e6 EB |
122 | if (err) |
123 | goto out_free_map; | |
33c42940 | 124 | ns->ns.ops = &pidns_operations; |
98f842e6 | 125 | |
74bd59bb | 126 | kref_init(&ns->kref); |
74bd59bb | 127 | ns->level = level; |
ed469a63 | 128 | ns->parent = get_pid_ns(parent_pid_ns); |
49f4d8b9 | 129 | ns->user_ns = get_user_ns(user_ns); |
f333c700 | 130 | ns->ucounts = ucounts; |
c876ad76 | 131 | ns->nr_hashed = PIDNS_HASH_ADDING; |
0a01f2cc | 132 | INIT_WORK(&ns->proc_work, proc_cleanup_work); |
74bd59bb PE |
133 | |
134 | set_bit(0, ns->pidmap[0].page); | |
135 | atomic_set(&ns->pidmap[0].nr_free, BITS_PER_PAGE - 1); | |
136 | ||
84406c15 | 137 | for (i = 1; i < PIDMAP_ENTRIES; i++) |
74bd59bb | 138 | atomic_set(&ns->pidmap[i].nr_free, BITS_PER_PAGE); |
74bd59bb PE |
139 | |
140 | return ns; | |
141 | ||
142 | out_free_map: | |
143 | kfree(ns->pidmap[0].page); | |
144 | out_free: | |
145 | kmem_cache_free(pid_ns_cachep, ns); | |
f333c700 EB |
146 | out_dec: |
147 | dec_pid_namespaces(ucounts); | |
74bd59bb | 148 | out: |
4308eebb | 149 | return ERR_PTR(err); |
74bd59bb PE |
150 | } |
151 | ||
1adfcb03 AV |
152 | static void delayed_free_pidns(struct rcu_head *p) |
153 | { | |
154 | kmem_cache_free(pid_ns_cachep, | |
155 | container_of(p, struct pid_namespace, rcu)); | |
156 | } | |
157 | ||
74bd59bb PE |
158 | static void destroy_pid_namespace(struct pid_namespace *ns) |
159 | { | |
160 | int i; | |
161 | ||
6344c433 | 162 | ns_free_inum(&ns->ns); |
74bd59bb PE |
163 | for (i = 0; i < PIDMAP_ENTRIES; i++) |
164 | kfree(ns->pidmap[i].page); | |
f333c700 | 165 | dec_pid_namespaces(ns->ucounts); |
49f4d8b9 | 166 | put_user_ns(ns->user_ns); |
1adfcb03 | 167 | call_rcu(&ns->rcu, delayed_free_pidns); |
74bd59bb PE |
168 | } |
169 | ||
49f4d8b9 EB |
170 | struct pid_namespace *copy_pid_ns(unsigned long flags, |
171 | struct user_namespace *user_ns, struct pid_namespace *old_ns) | |
74bd59bb | 172 | { |
74bd59bb | 173 | if (!(flags & CLONE_NEWPID)) |
dca4a979 | 174 | return get_pid_ns(old_ns); |
225778d6 EB |
175 | if (task_active_pid_ns(current) != old_ns) |
176 | return ERR_PTR(-EINVAL); | |
49f4d8b9 | 177 | return create_pid_namespace(user_ns, old_ns); |
74bd59bb PE |
178 | } |
179 | ||
bbc2e3ef | 180 | static void free_pid_ns(struct kref *kref) |
74bd59bb | 181 | { |
bbc2e3ef | 182 | struct pid_namespace *ns; |
74bd59bb PE |
183 | |
184 | ns = container_of(kref, struct pid_namespace, kref); | |
74bd59bb | 185 | destroy_pid_namespace(ns); |
bbc2e3ef | 186 | } |
74bd59bb | 187 | |
bbc2e3ef CG |
188 | void put_pid_ns(struct pid_namespace *ns) |
189 | { | |
190 | struct pid_namespace *parent; | |
191 | ||
192 | while (ns != &init_pid_ns) { | |
193 | parent = ns->parent; | |
194 | if (!kref_put(&ns->kref, free_pid_ns)) | |
195 | break; | |
196 | ns = parent; | |
197 | } | |
74bd59bb | 198 | } |
bbc2e3ef | 199 | EXPORT_SYMBOL_GPL(put_pid_ns); |
74bd59bb PE |
200 | |
201 | void zap_pid_ns_processes(struct pid_namespace *pid_ns) | |
202 | { | |
203 | int nr; | |
204 | int rc; | |
00c10bc1 | 205 | struct task_struct *task, *me = current; |
751c644b | 206 | int init_pids = thread_group_leader(me) ? 1 : 2; |
00c10bc1 | 207 | |
c876ad76 EB |
208 | /* Don't allow any more processes into the pid namespace */ |
209 | disable_pid_allocation(pid_ns); | |
210 | ||
a53b8315 ON |
211 | /* |
212 | * Ignore SIGCHLD causing any terminated children to autoreap. | |
213 | * This speeds up the namespace shutdown, plus see the comment | |
214 | * below. | |
215 | */ | |
00c10bc1 EB |
216 | spin_lock_irq(&me->sighand->siglock); |
217 | me->sighand->action[SIGCHLD - 1].sa.sa_handler = SIG_IGN; | |
218 | spin_unlock_irq(&me->sighand->siglock); | |
74bd59bb PE |
219 | |
220 | /* | |
221 | * The last thread in the cgroup-init thread group is terminating. | |
222 | * Find remaining pid_ts in the namespace, signal and wait for them | |
223 | * to exit. | |
224 | * | |
225 | * Note: This signals each threads in the namespace - even those that | |
226 | * belong to the same thread group, To avoid this, we would have | |
227 | * to walk the entire tasklist looking a processes in this | |
228 | * namespace, but that could be unnecessarily expensive if the | |
229 | * pid namespace has just a few processes. Or we need to | |
230 | * maintain a tasklist for each pid namespace. | |
231 | * | |
232 | */ | |
233 | read_lock(&tasklist_lock); | |
234 | nr = next_pidmap(pid_ns, 1); | |
235 | while (nr > 0) { | |
e4da026f SB |
236 | rcu_read_lock(); |
237 | ||
e4da026f | 238 | task = pid_task(find_vpid(nr), PIDTYPE_PID); |
a02d6fd6 ON |
239 | if (task && !__fatal_signal_pending(task)) |
240 | send_sig_info(SIGKILL, SEND_SIG_FORCED, task); | |
e4da026f SB |
241 | |
242 | rcu_read_unlock(); | |
243 | ||
74bd59bb PE |
244 | nr = next_pidmap(pid_ns, nr); |
245 | } | |
246 | read_unlock(&tasklist_lock); | |
247 | ||
a53b8315 ON |
248 | /* |
249 | * Reap the EXIT_ZOMBIE children we had before we ignored SIGCHLD. | |
250 | * sys_wait4() will also block until our children traced from the | |
251 | * parent namespace are detached and become EXIT_DEAD. | |
252 | */ | |
74bd59bb PE |
253 | do { |
254 | clear_thread_flag(TIF_SIGPENDING); | |
255 | rc = sys_wait4(-1, NULL, __WALL, NULL); | |
256 | } while (rc != -ECHILD); | |
257 | ||
6347e900 | 258 | /* |
a53b8315 ON |
259 | * sys_wait4() above can't reap the EXIT_DEAD children but we do not |
260 | * really care, we could reparent them to the global init. We could | |
261 | * exit and reap ->child_reaper even if it is not the last thread in | |
262 | * this pid_ns, free_pid(nr_hashed == 0) calls proc_cleanup_work(), | |
263 | * pid_ns can not go away until proc_kill_sb() drops the reference. | |
264 | * | |
265 | * But this ns can also have other tasks injected by setns()+fork(). | |
266 | * Again, ignoring the user visible semantics we do not really need | |
267 | * to wait until they are all reaped, but they can be reparented to | |
268 | * us and thus we need to ensure that pid->child_reaper stays valid | |
269 | * until they all go away. See free_pid()->wake_up_process(). | |
270 | * | |
271 | * We rely on ignored SIGCHLD, an injected zombie must be autoreaped | |
272 | * if reparented. | |
6347e900 EB |
273 | */ |
274 | for (;;) { | |
af4b8a83 | 275 | set_current_state(TASK_UNINTERRUPTIBLE); |
751c644b | 276 | if (pid_ns->nr_hashed == init_pids) |
6347e900 EB |
277 | break; |
278 | schedule(); | |
279 | } | |
af4b8a83 | 280 | __set_current_state(TASK_RUNNING); |
6347e900 | 281 | |
cf3f8921 DL |
282 | if (pid_ns->reboot) |
283 | current->signal->group_exit_code = pid_ns->reboot; | |
284 | ||
0b6b030f | 285 | acct_exit_ns(pid_ns); |
74bd59bb PE |
286 | return; |
287 | } | |
288 | ||
98ed57ee | 289 | #ifdef CONFIG_CHECKPOINT_RESTORE |
b8f566b0 PE |
290 | static int pid_ns_ctl_handler(struct ctl_table *table, int write, |
291 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
292 | { | |
49f4d8b9 | 293 | struct pid_namespace *pid_ns = task_active_pid_ns(current); |
b8f566b0 PE |
294 | struct ctl_table tmp = *table; |
295 | ||
49f4d8b9 | 296 | if (write && !ns_capable(pid_ns->user_ns, CAP_SYS_ADMIN)) |
b8f566b0 PE |
297 | return -EPERM; |
298 | ||
299 | /* | |
300 | * Writing directly to ns' last_pid field is OK, since this field | |
301 | * is volatile in a living namespace anyway and a code writing to | |
302 | * it should synchronize its usage with external means. | |
303 | */ | |
304 | ||
49f4d8b9 | 305 | tmp.data = &pid_ns->last_pid; |
579035dc | 306 | return proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos); |
b8f566b0 PE |
307 | } |
308 | ||
579035dc AV |
309 | extern int pid_max; |
310 | static int zero = 0; | |
b8f566b0 PE |
311 | static struct ctl_table pid_ns_ctl_table[] = { |
312 | { | |
313 | .procname = "ns_last_pid", | |
314 | .maxlen = sizeof(int), | |
315 | .mode = 0666, /* permissions are checked in the handler */ | |
316 | .proc_handler = pid_ns_ctl_handler, | |
579035dc AV |
317 | .extra1 = &zero, |
318 | .extra2 = &pid_max, | |
b8f566b0 PE |
319 | }, |
320 | { } | |
321 | }; | |
b8f566b0 | 322 | static struct ctl_path kern_path[] = { { .procname = "kernel", }, { } }; |
98ed57ee | 323 | #endif /* CONFIG_CHECKPOINT_RESTORE */ |
b8f566b0 | 324 | |
cf3f8921 DL |
325 | int reboot_pid_ns(struct pid_namespace *pid_ns, int cmd) |
326 | { | |
327 | if (pid_ns == &init_pid_ns) | |
328 | return 0; | |
329 | ||
330 | switch (cmd) { | |
331 | case LINUX_REBOOT_CMD_RESTART2: | |
332 | case LINUX_REBOOT_CMD_RESTART: | |
333 | pid_ns->reboot = SIGHUP; | |
334 | break; | |
335 | ||
336 | case LINUX_REBOOT_CMD_POWER_OFF: | |
337 | case LINUX_REBOOT_CMD_HALT: | |
338 | pid_ns->reboot = SIGINT; | |
339 | break; | |
340 | default: | |
341 | return -EINVAL; | |
342 | } | |
343 | ||
344 | read_lock(&tasklist_lock); | |
345 | force_sig(SIGKILL, pid_ns->child_reaper); | |
346 | read_unlock(&tasklist_lock); | |
347 | ||
348 | do_exit(0); | |
349 | ||
350 | /* Not reached */ | |
351 | return 0; | |
352 | } | |
353 | ||
3c041184 AV |
354 | static inline struct pid_namespace *to_pid_ns(struct ns_common *ns) |
355 | { | |
356 | return container_of(ns, struct pid_namespace, ns); | |
357 | } | |
358 | ||
64964528 | 359 | static struct ns_common *pidns_get(struct task_struct *task) |
57e8391d EB |
360 | { |
361 | struct pid_namespace *ns; | |
362 | ||
363 | rcu_read_lock(); | |
d2308225 ON |
364 | ns = task_active_pid_ns(task); |
365 | if (ns) | |
366 | get_pid_ns(ns); | |
57e8391d EB |
367 | rcu_read_unlock(); |
368 | ||
3c041184 | 369 | return ns ? &ns->ns : NULL; |
57e8391d EB |
370 | } |
371 | ||
64964528 | 372 | static void pidns_put(struct ns_common *ns) |
57e8391d | 373 | { |
3c041184 | 374 | put_pid_ns(to_pid_ns(ns)); |
57e8391d EB |
375 | } |
376 | ||
64964528 | 377 | static int pidns_install(struct nsproxy *nsproxy, struct ns_common *ns) |
57e8391d EB |
378 | { |
379 | struct pid_namespace *active = task_active_pid_ns(current); | |
3c041184 | 380 | struct pid_namespace *ancestor, *new = to_pid_ns(ns); |
57e8391d | 381 | |
5e4a0847 | 382 | if (!ns_capable(new->user_ns, CAP_SYS_ADMIN) || |
c7b96acf | 383 | !ns_capable(current_user_ns(), CAP_SYS_ADMIN)) |
57e8391d EB |
384 | return -EPERM; |
385 | ||
386 | /* | |
387 | * Only allow entering the current active pid namespace | |
388 | * or a child of the current active pid namespace. | |
389 | * | |
390 | * This is required for fork to return a usable pid value and | |
391 | * this maintains the property that processes and their | |
392 | * children can not escape their current pid namespace. | |
393 | */ | |
394 | if (new->level < active->level) | |
395 | return -EINVAL; | |
396 | ||
397 | ancestor = new; | |
398 | while (ancestor->level > active->level) | |
399 | ancestor = ancestor->parent; | |
400 | if (ancestor != active) | |
401 | return -EINVAL; | |
402 | ||
c2b1df2e AL |
403 | put_pid_ns(nsproxy->pid_ns_for_children); |
404 | nsproxy->pid_ns_for_children = get_pid_ns(new); | |
57e8391d EB |
405 | return 0; |
406 | } | |
407 | ||
a7306ed8 AV |
408 | static struct ns_common *pidns_get_parent(struct ns_common *ns) |
409 | { | |
410 | struct pid_namespace *active = task_active_pid_ns(current); | |
411 | struct pid_namespace *pid_ns, *p; | |
412 | ||
413 | /* See if the parent is in the current namespace */ | |
414 | pid_ns = p = to_pid_ns(ns)->parent; | |
415 | for (;;) { | |
416 | if (!p) | |
417 | return ERR_PTR(-EPERM); | |
418 | if (p == active) | |
419 | break; | |
420 | p = p->parent; | |
421 | } | |
422 | ||
423 | return &get_pid_ns(pid_ns)->ns; | |
424 | } | |
425 | ||
bcac25a5 AV |
426 | static struct user_namespace *pidns_owner(struct ns_common *ns) |
427 | { | |
428 | return to_pid_ns(ns)->user_ns; | |
429 | } | |
430 | ||
57e8391d EB |
431 | const struct proc_ns_operations pidns_operations = { |
432 | .name = "pid", | |
433 | .type = CLONE_NEWPID, | |
434 | .get = pidns_get, | |
435 | .put = pidns_put, | |
436 | .install = pidns_install, | |
bcac25a5 | 437 | .owner = pidns_owner, |
a7306ed8 | 438 | .get_parent = pidns_get_parent, |
57e8391d EB |
439 | }; |
440 | ||
74bd59bb PE |
441 | static __init int pid_namespaces_init(void) |
442 | { | |
443 | pid_ns_cachep = KMEM_CACHE(pid_namespace, SLAB_PANIC); | |
98ed57ee CG |
444 | |
445 | #ifdef CONFIG_CHECKPOINT_RESTORE | |
b8f566b0 | 446 | register_sysctl_paths(kern_path, pid_ns_ctl_table); |
98ed57ee | 447 | #endif |
74bd59bb PE |
448 | return 0; |
449 | } | |
450 | ||
451 | __initcall(pid_namespaces_init); |