Commit | Line | Data |
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457c8996 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
74bd59bb PE |
2 | /* |
3 | * Pid namespaces | |
4 | * | |
5 | * Authors: | |
6 | * (C) 2007 Pavel Emelyanov <xemul@openvz.org>, OpenVZ, SWsoft Inc. | |
7 | * (C) 2007 Sukadev Bhattiprolu <sukadev@us.ibm.com>, IBM | |
8 | * Many thanks to Oleg Nesterov for comments and help | |
9 | * | |
10 | */ | |
11 | ||
12 | #include <linux/pid.h> | |
13 | #include <linux/pid_namespace.h> | |
49f4d8b9 | 14 | #include <linux/user_namespace.h> |
74bd59bb | 15 | #include <linux/syscalls.h> |
5b825c3a | 16 | #include <linux/cred.h> |
74bd59bb | 17 | #include <linux/err.h> |
0b6b030f | 18 | #include <linux/acct.h> |
5a0e3ad6 | 19 | #include <linux/slab.h> |
0bb80f24 | 20 | #include <linux/proc_ns.h> |
cf3f8921 | 21 | #include <linux/reboot.h> |
523a6a94 | 22 | #include <linux/export.h> |
29930025 | 23 | #include <linux/sched/task.h> |
f361bf4a | 24 | #include <linux/sched/signal.h> |
95846ecf | 25 | #include <linux/idr.h> |
105ff533 | 26 | #include "pid_sysctl.h" |
74bd59bb | 27 | |
74bd59bb PE |
28 | static DEFINE_MUTEX(pid_caches_mutex); |
29 | static struct kmem_cache *pid_ns_cachep; | |
dd206bec AD |
30 | /* Write once array, filled from the beginning. */ |
31 | static struct kmem_cache *pid_cache[MAX_PID_NS_LEVEL]; | |
74bd59bb PE |
32 | |
33 | /* | |
34 | * creates the kmem cache to allocate pids from. | |
dd206bec | 35 | * @level: pid namespace level |
74bd59bb PE |
36 | */ |
37 | ||
dd206bec | 38 | static struct kmem_cache *create_pid_cachep(unsigned int level) |
74bd59bb | 39 | { |
dd206bec AD |
40 | /* Level 0 is init_pid_ns.pid_cachep */ |
41 | struct kmem_cache **pkc = &pid_cache[level - 1]; | |
42 | struct kmem_cache *kc; | |
43 | char name[4 + 10 + 1]; | |
44 | unsigned int len; | |
45 | ||
46 | kc = READ_ONCE(*pkc); | |
47 | if (kc) | |
48 | return kc; | |
49 | ||
50 | snprintf(name, sizeof(name), "pid_%u", level + 1); | |
dd546618 | 51 | len = struct_size_t(struct pid, numbers, level + 1); |
74bd59bb | 52 | mutex_lock(&pid_caches_mutex); |
dd206bec AD |
53 | /* Name collision forces to do allocation under mutex. */ |
54 | if (!*pkc) | |
fab827db | 55 | *pkc = kmem_cache_create(name, len, 0, |
c06d7aaf | 56 | SLAB_HWCACHE_ALIGN | SLAB_ACCOUNT, NULL); |
74bd59bb | 57 | mutex_unlock(&pid_caches_mutex); |
dd206bec AD |
58 | /* current can fail, but someone else can succeed. */ |
59 | return READ_ONCE(*pkc); | |
74bd59bb PE |
60 | } |
61 | ||
f333c700 EB |
62 | static struct ucounts *inc_pid_namespaces(struct user_namespace *ns) |
63 | { | |
64 | return inc_ucount(ns, current_euid(), UCOUNT_PID_NAMESPACES); | |
65 | } | |
66 | ||
67 | static void dec_pid_namespaces(struct ucounts *ucounts) | |
68 | { | |
69 | dec_ucount(ucounts, UCOUNT_PID_NAMESPACES); | |
70 | } | |
71 | ||
49f4d8b9 EB |
72 | static struct pid_namespace *create_pid_namespace(struct user_namespace *user_ns, |
73 | struct pid_namespace *parent_pid_ns) | |
74bd59bb PE |
74 | { |
75 | struct pid_namespace *ns; | |
ed469a63 | 76 | unsigned int level = parent_pid_ns->level + 1; |
f333c700 | 77 | struct ucounts *ucounts; |
f2302505 AV |
78 | int err; |
79 | ||
a2b42626 EB |
80 | err = -EINVAL; |
81 | if (!in_userns(parent_pid_ns->user_ns, user_ns)) | |
82 | goto out; | |
83 | ||
df75e774 | 84 | err = -ENOSPC; |
f333c700 EB |
85 | if (level > MAX_PID_NS_LEVEL) |
86 | goto out; | |
87 | ucounts = inc_pid_namespaces(user_ns); | |
88 | if (!ucounts) | |
f2302505 | 89 | goto out; |
74bd59bb | 90 | |
f2302505 | 91 | err = -ENOMEM; |
84406c15 | 92 | ns = kmem_cache_zalloc(pid_ns_cachep, GFP_KERNEL); |
74bd59bb | 93 | if (ns == NULL) |
f333c700 | 94 | goto out_dec; |
74bd59bb | 95 | |
95846ecf | 96 | idr_init(&ns->idr); |
74bd59bb | 97 | |
dd206bec | 98 | ns->pid_cachep = create_pid_cachep(level); |
74bd59bb | 99 | if (ns->pid_cachep == NULL) |
95846ecf | 100 | goto out_free_idr; |
74bd59bb | 101 | |
6344c433 | 102 | err = ns_alloc_inum(&ns->ns); |
98f842e6 | 103 | if (err) |
95846ecf | 104 | goto out_free_idr; |
33c42940 | 105 | ns->ns.ops = &pidns_operations; |
98f842e6 | 106 | |
8eb71d95 | 107 | refcount_set(&ns->ns.count, 1); |
74bd59bb | 108 | ns->level = level; |
ed469a63 | 109 | ns->parent = get_pid_ns(parent_pid_ns); |
49f4d8b9 | 110 | ns->user_ns = get_user_ns(user_ns); |
f333c700 | 111 | ns->ucounts = ucounts; |
e8cfbc24 | 112 | ns->pid_allocated = PIDNS_ADDING; |
9876cfe8 AS |
113 | #if defined(CONFIG_SYSCTL) && defined(CONFIG_MEMFD_CREATE) |
114 | ns->memfd_noexec_scope = pidns_memfd_noexec_scope(parent_pid_ns); | |
115 | #endif | |
74bd59bb PE |
116 | return ns; |
117 | ||
95846ecf GS |
118 | out_free_idr: |
119 | idr_destroy(&ns->idr); | |
74bd59bb | 120 | kmem_cache_free(pid_ns_cachep, ns); |
f333c700 EB |
121 | out_dec: |
122 | dec_pid_namespaces(ucounts); | |
74bd59bb | 123 | out: |
4308eebb | 124 | return ERR_PTR(err); |
74bd59bb PE |
125 | } |
126 | ||
1adfcb03 AV |
127 | static void delayed_free_pidns(struct rcu_head *p) |
128 | { | |
add7c65c AV |
129 | struct pid_namespace *ns = container_of(p, struct pid_namespace, rcu); |
130 | ||
131 | dec_pid_namespaces(ns->ucounts); | |
132 | put_user_ns(ns->user_ns); | |
133 | ||
134 | kmem_cache_free(pid_ns_cachep, ns); | |
1adfcb03 AV |
135 | } |
136 | ||
74bd59bb PE |
137 | static void destroy_pid_namespace(struct pid_namespace *ns) |
138 | { | |
6344c433 | 139 | ns_free_inum(&ns->ns); |
95846ecf GS |
140 | |
141 | idr_destroy(&ns->idr); | |
1adfcb03 | 142 | call_rcu(&ns->rcu, delayed_free_pidns); |
74bd59bb PE |
143 | } |
144 | ||
49f4d8b9 EB |
145 | struct pid_namespace *copy_pid_ns(unsigned long flags, |
146 | struct user_namespace *user_ns, struct pid_namespace *old_ns) | |
74bd59bb | 147 | { |
74bd59bb | 148 | if (!(flags & CLONE_NEWPID)) |
dca4a979 | 149 | return get_pid_ns(old_ns); |
225778d6 EB |
150 | if (task_active_pid_ns(current) != old_ns) |
151 | return ERR_PTR(-EINVAL); | |
49f4d8b9 | 152 | return create_pid_namespace(user_ns, old_ns); |
74bd59bb PE |
153 | } |
154 | ||
bbc2e3ef CG |
155 | void put_pid_ns(struct pid_namespace *ns) |
156 | { | |
157 | struct pid_namespace *parent; | |
158 | ||
159 | while (ns != &init_pid_ns) { | |
160 | parent = ns->parent; | |
8eb71d95 | 161 | if (!refcount_dec_and_test(&ns->ns.count)) |
bbc2e3ef | 162 | break; |
8eb71d95 | 163 | destroy_pid_namespace(ns); |
bbc2e3ef CG |
164 | ns = parent; |
165 | } | |
74bd59bb | 166 | } |
bbc2e3ef | 167 | EXPORT_SYMBOL_GPL(put_pid_ns); |
74bd59bb PE |
168 | |
169 | void zap_pid_ns_processes(struct pid_namespace *pid_ns) | |
170 | { | |
171 | int nr; | |
172 | int rc; | |
00c10bc1 | 173 | struct task_struct *task, *me = current; |
751c644b | 174 | int init_pids = thread_group_leader(me) ? 1 : 2; |
95846ecf | 175 | struct pid *pid; |
00c10bc1 | 176 | |
c876ad76 EB |
177 | /* Don't allow any more processes into the pid namespace */ |
178 | disable_pid_allocation(pid_ns); | |
179 | ||
a53b8315 ON |
180 | /* |
181 | * Ignore SIGCHLD causing any terminated children to autoreap. | |
182 | * This speeds up the namespace shutdown, plus see the comment | |
183 | * below. | |
184 | */ | |
00c10bc1 EB |
185 | spin_lock_irq(&me->sighand->siglock); |
186 | me->sighand->action[SIGCHLD - 1].sa.sa_handler = SIG_IGN; | |
187 | spin_unlock_irq(&me->sighand->siglock); | |
74bd59bb PE |
188 | |
189 | /* | |
190 | * The last thread in the cgroup-init thread group is terminating. | |
191 | * Find remaining pid_ts in the namespace, signal and wait for them | |
192 | * to exit. | |
193 | * | |
194 | * Note: This signals each threads in the namespace - even those that | |
195 | * belong to the same thread group, To avoid this, we would have | |
196 | * to walk the entire tasklist looking a processes in this | |
197 | * namespace, but that could be unnecessarily expensive if the | |
198 | * pid namespace has just a few processes. Or we need to | |
199 | * maintain a tasklist for each pid namespace. | |
200 | * | |
201 | */ | |
95846ecf | 202 | rcu_read_lock(); |
74bd59bb | 203 | read_lock(&tasklist_lock); |
95846ecf GS |
204 | nr = 2; |
205 | idr_for_each_entry_continue(&pid_ns->idr, pid, nr) { | |
206 | task = pid_task(pid, PIDTYPE_PID); | |
a02d6fd6 | 207 | if (task && !__fatal_signal_pending(task)) |
82058d66 | 208 | group_send_sig_info(SIGKILL, SEND_SIG_PRIV, task, PIDTYPE_MAX); |
74bd59bb PE |
209 | } |
210 | read_unlock(&tasklist_lock); | |
95846ecf | 211 | rcu_read_unlock(); |
74bd59bb | 212 | |
a53b8315 ON |
213 | /* |
214 | * Reap the EXIT_ZOMBIE children we had before we ignored SIGCHLD. | |
d300b610 | 215 | * kernel_wait4() will also block until our children traced from the |
a53b8315 ON |
216 | * parent namespace are detached and become EXIT_DEAD. |
217 | */ | |
74bd59bb PE |
218 | do { |
219 | clear_thread_flag(TIF_SIGPENDING); | |
d300b610 | 220 | rc = kernel_wait4(-1, NULL, __WALL, NULL); |
74bd59bb PE |
221 | } while (rc != -ECHILD); |
222 | ||
6347e900 | 223 | /* |
af9fe6d6 EB |
224 | * kernel_wait4() misses EXIT_DEAD children, and EXIT_ZOMBIE |
225 | * process whose parents processes are outside of the pid | |
226 | * namespace. Such processes are created with setns()+fork(). | |
a53b8315 | 227 | * |
af9fe6d6 EB |
228 | * If those EXIT_ZOMBIE processes are not reaped by their |
229 | * parents before their parents exit, they will be reparented | |
230 | * to pid_ns->child_reaper. Thus pidns->child_reaper needs to | |
231 | * stay valid until they all go away. | |
a53b8315 | 232 | * |
7b7b8a2c | 233 | * The code relies on the pid_ns->child_reaper ignoring |
af9fe6d6 EB |
234 | * SIGCHILD to cause those EXIT_ZOMBIE processes to be |
235 | * autoreaped if reparented. | |
236 | * | |
237 | * Semantically it is also desirable to wait for EXIT_ZOMBIE | |
238 | * processes before allowing the child_reaper to be reaped, as | |
239 | * that gives the invariant that when the init process of a | |
240 | * pid namespace is reaped all of the processes in the pid | |
241 | * namespace are gone. | |
242 | * | |
243 | * Once all of the other tasks are gone from the pid_namespace | |
244 | * free_pid() will awaken this task. | |
6347e900 EB |
245 | */ |
246 | for (;;) { | |
b9a985db | 247 | set_current_state(TASK_INTERRUPTIBLE); |
e8cfbc24 | 248 | if (pid_ns->pid_allocated == init_pids) |
6347e900 | 249 | break; |
28319d6d FW |
250 | /* |
251 | * Release tasks_rcu_exit_srcu to avoid following deadlock: | |
252 | * | |
253 | * 1) TASK A unshare(CLONE_NEWPID) | |
254 | * 2) TASK A fork() twice -> TASK B (child reaper for new ns) | |
255 | * and TASK C | |
256 | * 3) TASK B exits, kills TASK C, waits for TASK A to reap it | |
257 | * 4) TASK A calls synchronize_rcu_tasks() | |
258 | * -> synchronize_srcu(tasks_rcu_exit_srcu) | |
259 | * 5) *DEADLOCK* | |
260 | * | |
261 | * It is considered safe to release tasks_rcu_exit_srcu here | |
262 | * because we assume the current task can not be concurrently | |
263 | * reaped at this point. | |
264 | */ | |
265 | exit_tasks_rcu_stop(); | |
6347e900 | 266 | schedule(); |
28319d6d | 267 | exit_tasks_rcu_start(); |
6347e900 | 268 | } |
af4b8a83 | 269 | __set_current_state(TASK_RUNNING); |
6347e900 | 270 | |
cf3f8921 DL |
271 | if (pid_ns->reboot) |
272 | current->signal->group_exit_code = pid_ns->reboot; | |
273 | ||
0b6b030f | 274 | acct_exit_ns(pid_ns); |
74bd59bb PE |
275 | return; |
276 | } | |
277 | ||
98ed57ee | 278 | #ifdef CONFIG_CHECKPOINT_RESTORE |
b8f566b0 | 279 | static int pid_ns_ctl_handler(struct ctl_table *table, int write, |
32927393 | 280 | void *buffer, size_t *lenp, loff_t *ppos) |
b8f566b0 | 281 | { |
49f4d8b9 | 282 | struct pid_namespace *pid_ns = task_active_pid_ns(current); |
b8f566b0 | 283 | struct ctl_table tmp = *table; |
95846ecf | 284 | int ret, next; |
b8f566b0 | 285 | |
b9a3db92 | 286 | if (write && !checkpoint_restore_ns_capable(pid_ns->user_ns)) |
b8f566b0 PE |
287 | return -EPERM; |
288 | ||
289 | /* | |
290 | * Writing directly to ns' last_pid field is OK, since this field | |
291 | * is volatile in a living namespace anyway and a code writing to | |
292 | * it should synchronize its usage with external means. | |
293 | */ | |
294 | ||
95846ecf GS |
295 | next = idr_get_cursor(&pid_ns->idr) - 1; |
296 | ||
297 | tmp.data = &next; | |
298 | ret = proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos); | |
299 | if (!ret && write) | |
300 | idr_set_cursor(&pid_ns->idr, next + 1); | |
301 | ||
302 | return ret; | |
b8f566b0 PE |
303 | } |
304 | ||
579035dc | 305 | extern int pid_max; |
b8f566b0 PE |
306 | static struct ctl_table pid_ns_ctl_table[] = { |
307 | { | |
308 | .procname = "ns_last_pid", | |
309 | .maxlen = sizeof(int), | |
310 | .mode = 0666, /* permissions are checked in the handler */ | |
311 | .proc_handler = pid_ns_ctl_handler, | |
eec4844f | 312 | .extra1 = SYSCTL_ZERO, |
579035dc | 313 | .extra2 = &pid_max, |
b8f566b0 PE |
314 | }, |
315 | { } | |
316 | }; | |
98ed57ee | 317 | #endif /* CONFIG_CHECKPOINT_RESTORE */ |
b8f566b0 | 318 | |
cf3f8921 DL |
319 | int reboot_pid_ns(struct pid_namespace *pid_ns, int cmd) |
320 | { | |
321 | if (pid_ns == &init_pid_ns) | |
322 | return 0; | |
323 | ||
324 | switch (cmd) { | |
325 | case LINUX_REBOOT_CMD_RESTART2: | |
326 | case LINUX_REBOOT_CMD_RESTART: | |
327 | pid_ns->reboot = SIGHUP; | |
328 | break; | |
329 | ||
330 | case LINUX_REBOOT_CMD_POWER_OFF: | |
331 | case LINUX_REBOOT_CMD_HALT: | |
332 | pid_ns->reboot = SIGINT; | |
333 | break; | |
334 | default: | |
335 | return -EINVAL; | |
336 | } | |
337 | ||
338 | read_lock(&tasklist_lock); | |
f9070dc9 | 339 | send_sig(SIGKILL, pid_ns->child_reaper, 1); |
cf3f8921 DL |
340 | read_unlock(&tasklist_lock); |
341 | ||
342 | do_exit(0); | |
343 | ||
344 | /* Not reached */ | |
345 | return 0; | |
346 | } | |
347 | ||
3c041184 AV |
348 | static inline struct pid_namespace *to_pid_ns(struct ns_common *ns) |
349 | { | |
350 | return container_of(ns, struct pid_namespace, ns); | |
351 | } | |
352 | ||
64964528 | 353 | static struct ns_common *pidns_get(struct task_struct *task) |
57e8391d EB |
354 | { |
355 | struct pid_namespace *ns; | |
356 | ||
357 | rcu_read_lock(); | |
d2308225 ON |
358 | ns = task_active_pid_ns(task); |
359 | if (ns) | |
360 | get_pid_ns(ns); | |
57e8391d EB |
361 | rcu_read_unlock(); |
362 | ||
3c041184 | 363 | return ns ? &ns->ns : NULL; |
57e8391d EB |
364 | } |
365 | ||
eaa0d190 KT |
366 | static struct ns_common *pidns_for_children_get(struct task_struct *task) |
367 | { | |
368 | struct pid_namespace *ns = NULL; | |
369 | ||
370 | task_lock(task); | |
371 | if (task->nsproxy) { | |
372 | ns = task->nsproxy->pid_ns_for_children; | |
373 | get_pid_ns(ns); | |
374 | } | |
375 | task_unlock(task); | |
376 | ||
377 | if (ns) { | |
378 | read_lock(&tasklist_lock); | |
379 | if (!ns->child_reaper) { | |
380 | put_pid_ns(ns); | |
381 | ns = NULL; | |
382 | } | |
383 | read_unlock(&tasklist_lock); | |
384 | } | |
385 | ||
386 | return ns ? &ns->ns : NULL; | |
387 | } | |
388 | ||
64964528 | 389 | static void pidns_put(struct ns_common *ns) |
57e8391d | 390 | { |
3c041184 | 391 | put_pid_ns(to_pid_ns(ns)); |
57e8391d EB |
392 | } |
393 | ||
f2a8d52e | 394 | static int pidns_install(struct nsset *nsset, struct ns_common *ns) |
57e8391d | 395 | { |
f2a8d52e | 396 | struct nsproxy *nsproxy = nsset->nsproxy; |
57e8391d | 397 | struct pid_namespace *active = task_active_pid_ns(current); |
3c041184 | 398 | struct pid_namespace *ancestor, *new = to_pid_ns(ns); |
57e8391d | 399 | |
5e4a0847 | 400 | if (!ns_capable(new->user_ns, CAP_SYS_ADMIN) || |
f2a8d52e | 401 | !ns_capable(nsset->cred->user_ns, CAP_SYS_ADMIN)) |
57e8391d EB |
402 | return -EPERM; |
403 | ||
404 | /* | |
405 | * Only allow entering the current active pid namespace | |
406 | * or a child of the current active pid namespace. | |
407 | * | |
408 | * This is required for fork to return a usable pid value and | |
409 | * this maintains the property that processes and their | |
410 | * children can not escape their current pid namespace. | |
411 | */ | |
412 | if (new->level < active->level) | |
413 | return -EINVAL; | |
414 | ||
415 | ancestor = new; | |
416 | while (ancestor->level > active->level) | |
417 | ancestor = ancestor->parent; | |
418 | if (ancestor != active) | |
419 | return -EINVAL; | |
420 | ||
c2b1df2e AL |
421 | put_pid_ns(nsproxy->pid_ns_for_children); |
422 | nsproxy->pid_ns_for_children = get_pid_ns(new); | |
57e8391d EB |
423 | return 0; |
424 | } | |
425 | ||
a7306ed8 AV |
426 | static struct ns_common *pidns_get_parent(struct ns_common *ns) |
427 | { | |
428 | struct pid_namespace *active = task_active_pid_ns(current); | |
429 | struct pid_namespace *pid_ns, *p; | |
430 | ||
431 | /* See if the parent is in the current namespace */ | |
432 | pid_ns = p = to_pid_ns(ns)->parent; | |
433 | for (;;) { | |
434 | if (!p) | |
435 | return ERR_PTR(-EPERM); | |
436 | if (p == active) | |
437 | break; | |
438 | p = p->parent; | |
439 | } | |
440 | ||
441 | return &get_pid_ns(pid_ns)->ns; | |
442 | } | |
443 | ||
bcac25a5 AV |
444 | static struct user_namespace *pidns_owner(struct ns_common *ns) |
445 | { | |
446 | return to_pid_ns(ns)->user_ns; | |
447 | } | |
448 | ||
57e8391d EB |
449 | const struct proc_ns_operations pidns_operations = { |
450 | .name = "pid", | |
451 | .type = CLONE_NEWPID, | |
452 | .get = pidns_get, | |
453 | .put = pidns_put, | |
454 | .install = pidns_install, | |
bcac25a5 | 455 | .owner = pidns_owner, |
a7306ed8 | 456 | .get_parent = pidns_get_parent, |
57e8391d EB |
457 | }; |
458 | ||
eaa0d190 KT |
459 | const struct proc_ns_operations pidns_for_children_operations = { |
460 | .name = "pid_for_children", | |
461 | .real_ns_name = "pid", | |
462 | .type = CLONE_NEWPID, | |
463 | .get = pidns_for_children_get, | |
464 | .put = pidns_put, | |
465 | .install = pidns_install, | |
466 | .owner = pidns_owner, | |
467 | .get_parent = pidns_get_parent, | |
468 | }; | |
469 | ||
74bd59bb PE |
470 | static __init int pid_namespaces_init(void) |
471 | { | |
30acd0bd | 472 | pid_ns_cachep = KMEM_CACHE(pid_namespace, SLAB_PANIC | SLAB_ACCOUNT); |
98ed57ee CG |
473 | |
474 | #ifdef CONFIG_CHECKPOINT_RESTORE | |
9e7c73c0 | 475 | register_sysctl_init("kernel", pid_ns_ctl_table); |
98ed57ee | 476 | #endif |
105ff533 JX |
477 | |
478 | register_pid_ns_sysctl_table_vm(); | |
74bd59bb PE |
479 | return 0; |
480 | } | |
481 | ||
482 | __initcall(pid_namespaces_init); |