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> |
4308eebb | 18 | #include <linux/proc_fs.h> |
cf3f8921 | 19 | #include <linux/reboot.h> |
523a6a94 | 20 | #include <linux/export.h> |
74bd59bb PE |
21 | |
22 | #define BITS_PER_PAGE (PAGE_SIZE*8) | |
23 | ||
24 | struct pid_cache { | |
25 | int nr_ids; | |
26 | char name[16]; | |
27 | struct kmem_cache *cachep; | |
28 | struct list_head list; | |
29 | }; | |
30 | ||
31 | static LIST_HEAD(pid_caches_lh); | |
32 | static DEFINE_MUTEX(pid_caches_mutex); | |
33 | static struct kmem_cache *pid_ns_cachep; | |
34 | ||
35 | /* | |
36 | * creates the kmem cache to allocate pids from. | |
37 | * @nr_ids: the number of numerical ids this pid will have to carry | |
38 | */ | |
39 | ||
40 | static struct kmem_cache *create_pid_cachep(int nr_ids) | |
41 | { | |
42 | struct pid_cache *pcache; | |
43 | struct kmem_cache *cachep; | |
44 | ||
45 | mutex_lock(&pid_caches_mutex); | |
46 | list_for_each_entry(pcache, &pid_caches_lh, list) | |
47 | if (pcache->nr_ids == nr_ids) | |
48 | goto out; | |
49 | ||
50 | pcache = kmalloc(sizeof(struct pid_cache), GFP_KERNEL); | |
51 | if (pcache == NULL) | |
52 | goto err_alloc; | |
53 | ||
54 | snprintf(pcache->name, sizeof(pcache->name), "pid_%d", nr_ids); | |
55 | cachep = kmem_cache_create(pcache->name, | |
56 | sizeof(struct pid) + (nr_ids - 1) * sizeof(struct upid), | |
57 | 0, SLAB_HWCACHE_ALIGN, NULL); | |
58 | if (cachep == NULL) | |
59 | goto err_cachep; | |
60 | ||
61 | pcache->nr_ids = nr_ids; | |
62 | pcache->cachep = cachep; | |
63 | list_add(&pcache->list, &pid_caches_lh); | |
64 | out: | |
65 | mutex_unlock(&pid_caches_mutex); | |
66 | return pcache->cachep; | |
67 | ||
68 | err_cachep: | |
69 | kfree(pcache); | |
70 | err_alloc: | |
71 | mutex_unlock(&pid_caches_mutex); | |
72 | return NULL; | |
73 | } | |
74 | ||
0a01f2cc EB |
75 | static void proc_cleanup_work(struct work_struct *work) |
76 | { | |
77 | struct pid_namespace *ns = container_of(work, struct pid_namespace, proc_work); | |
78 | pid_ns_release_proc(ns); | |
79 | } | |
80 | ||
f2302505 AV |
81 | /* MAX_PID_NS_LEVEL is needed for limiting size of 'struct pid' */ |
82 | #define MAX_PID_NS_LEVEL 32 | |
83 | ||
49f4d8b9 EB |
84 | static struct pid_namespace *create_pid_namespace(struct user_namespace *user_ns, |
85 | struct pid_namespace *parent_pid_ns) | |
74bd59bb PE |
86 | { |
87 | struct pid_namespace *ns; | |
ed469a63 | 88 | unsigned int level = parent_pid_ns->level + 1; |
f2302505 AV |
89 | int i; |
90 | int err; | |
91 | ||
92 | if (level > MAX_PID_NS_LEVEL) { | |
93 | err = -EINVAL; | |
94 | goto out; | |
95 | } | |
74bd59bb | 96 | |
f2302505 | 97 | err = -ENOMEM; |
84406c15 | 98 | ns = kmem_cache_zalloc(pid_ns_cachep, GFP_KERNEL); |
74bd59bb PE |
99 | if (ns == NULL) |
100 | goto out; | |
101 | ||
102 | ns->pidmap[0].page = kzalloc(PAGE_SIZE, GFP_KERNEL); | |
103 | if (!ns->pidmap[0].page) | |
104 | goto out_free; | |
105 | ||
106 | ns->pid_cachep = create_pid_cachep(level + 1); | |
107 | if (ns->pid_cachep == NULL) | |
108 | goto out_free_map; | |
109 | ||
98f842e6 EB |
110 | err = proc_alloc_inum(&ns->proc_inum); |
111 | if (err) | |
112 | goto out_free_map; | |
113 | ||
74bd59bb | 114 | kref_init(&ns->kref); |
74bd59bb | 115 | ns->level = level; |
ed469a63 | 116 | ns->parent = get_pid_ns(parent_pid_ns); |
49f4d8b9 | 117 | ns->user_ns = get_user_ns(user_ns); |
c876ad76 | 118 | ns->nr_hashed = PIDNS_HASH_ADDING; |
0a01f2cc | 119 | INIT_WORK(&ns->proc_work, proc_cleanup_work); |
74bd59bb PE |
120 | |
121 | set_bit(0, ns->pidmap[0].page); | |
122 | atomic_set(&ns->pidmap[0].nr_free, BITS_PER_PAGE - 1); | |
123 | ||
84406c15 | 124 | for (i = 1; i < PIDMAP_ENTRIES; i++) |
74bd59bb | 125 | atomic_set(&ns->pidmap[i].nr_free, BITS_PER_PAGE); |
74bd59bb PE |
126 | |
127 | return ns; | |
128 | ||
129 | out_free_map: | |
130 | kfree(ns->pidmap[0].page); | |
131 | out_free: | |
132 | kmem_cache_free(pid_ns_cachep, ns); | |
133 | out: | |
4308eebb | 134 | return ERR_PTR(err); |
74bd59bb PE |
135 | } |
136 | ||
137 | static void destroy_pid_namespace(struct pid_namespace *ns) | |
138 | { | |
139 | int i; | |
140 | ||
98f842e6 | 141 | proc_free_inum(ns->proc_inum); |
74bd59bb PE |
142 | for (i = 0; i < PIDMAP_ENTRIES; i++) |
143 | kfree(ns->pidmap[i].page); | |
49f4d8b9 | 144 | put_user_ns(ns->user_ns); |
74bd59bb PE |
145 | kmem_cache_free(pid_ns_cachep, ns); |
146 | } | |
147 | ||
49f4d8b9 EB |
148 | struct pid_namespace *copy_pid_ns(unsigned long flags, |
149 | struct user_namespace *user_ns, struct pid_namespace *old_ns) | |
74bd59bb | 150 | { |
74bd59bb | 151 | if (!(flags & CLONE_NEWPID)) |
dca4a979 | 152 | return get_pid_ns(old_ns); |
225778d6 EB |
153 | if (task_active_pid_ns(current) != old_ns) |
154 | return ERR_PTR(-EINVAL); | |
49f4d8b9 | 155 | return create_pid_namespace(user_ns, old_ns); |
74bd59bb PE |
156 | } |
157 | ||
bbc2e3ef | 158 | static void free_pid_ns(struct kref *kref) |
74bd59bb | 159 | { |
bbc2e3ef | 160 | struct pid_namespace *ns; |
74bd59bb PE |
161 | |
162 | ns = container_of(kref, struct pid_namespace, kref); | |
74bd59bb | 163 | destroy_pid_namespace(ns); |
bbc2e3ef | 164 | } |
74bd59bb | 165 | |
bbc2e3ef CG |
166 | void put_pid_ns(struct pid_namespace *ns) |
167 | { | |
168 | struct pid_namespace *parent; | |
169 | ||
170 | while (ns != &init_pid_ns) { | |
171 | parent = ns->parent; | |
172 | if (!kref_put(&ns->kref, free_pid_ns)) | |
173 | break; | |
174 | ns = parent; | |
175 | } | |
74bd59bb | 176 | } |
bbc2e3ef | 177 | EXPORT_SYMBOL_GPL(put_pid_ns); |
74bd59bb PE |
178 | |
179 | void zap_pid_ns_processes(struct pid_namespace *pid_ns) | |
180 | { | |
181 | int nr; | |
182 | int rc; | |
00c10bc1 | 183 | struct task_struct *task, *me = current; |
751c644b | 184 | int init_pids = thread_group_leader(me) ? 1 : 2; |
00c10bc1 | 185 | |
c876ad76 EB |
186 | /* Don't allow any more processes into the pid namespace */ |
187 | disable_pid_allocation(pid_ns); | |
188 | ||
00c10bc1 EB |
189 | /* Ignore SIGCHLD causing any terminated children to autoreap */ |
190 | spin_lock_irq(&me->sighand->siglock); | |
191 | me->sighand->action[SIGCHLD - 1].sa.sa_handler = SIG_IGN; | |
192 | spin_unlock_irq(&me->sighand->siglock); | |
74bd59bb PE |
193 | |
194 | /* | |
195 | * The last thread in the cgroup-init thread group is terminating. | |
196 | * Find remaining pid_ts in the namespace, signal and wait for them | |
197 | * to exit. | |
198 | * | |
199 | * Note: This signals each threads in the namespace - even those that | |
200 | * belong to the same thread group, To avoid this, we would have | |
201 | * to walk the entire tasklist looking a processes in this | |
202 | * namespace, but that could be unnecessarily expensive if the | |
203 | * pid namespace has just a few processes. Or we need to | |
204 | * maintain a tasklist for each pid namespace. | |
205 | * | |
206 | */ | |
207 | read_lock(&tasklist_lock); | |
208 | nr = next_pidmap(pid_ns, 1); | |
209 | while (nr > 0) { | |
e4da026f SB |
210 | rcu_read_lock(); |
211 | ||
e4da026f | 212 | task = pid_task(find_vpid(nr), PIDTYPE_PID); |
a02d6fd6 ON |
213 | if (task && !__fatal_signal_pending(task)) |
214 | send_sig_info(SIGKILL, SEND_SIG_FORCED, task); | |
e4da026f SB |
215 | |
216 | rcu_read_unlock(); | |
217 | ||
74bd59bb PE |
218 | nr = next_pidmap(pid_ns, nr); |
219 | } | |
220 | read_unlock(&tasklist_lock); | |
221 | ||
6347e900 | 222 | /* Firstly reap the EXIT_ZOMBIE children we may have. */ |
74bd59bb PE |
223 | do { |
224 | clear_thread_flag(TIF_SIGPENDING); | |
225 | rc = sys_wait4(-1, NULL, __WALL, NULL); | |
226 | } while (rc != -ECHILD); | |
227 | ||
6347e900 EB |
228 | /* |
229 | * sys_wait4() above can't reap the TASK_DEAD children. | |
af4b8a83 | 230 | * Make sure they all go away, see free_pid(). |
6347e900 EB |
231 | */ |
232 | for (;;) { | |
af4b8a83 | 233 | set_current_state(TASK_UNINTERRUPTIBLE); |
751c644b | 234 | if (pid_ns->nr_hashed == init_pids) |
6347e900 EB |
235 | break; |
236 | schedule(); | |
237 | } | |
af4b8a83 | 238 | __set_current_state(TASK_RUNNING); |
6347e900 | 239 | |
cf3f8921 DL |
240 | if (pid_ns->reboot) |
241 | current->signal->group_exit_code = pid_ns->reboot; | |
242 | ||
0b6b030f | 243 | acct_exit_ns(pid_ns); |
74bd59bb PE |
244 | return; |
245 | } | |
246 | ||
98ed57ee | 247 | #ifdef CONFIG_CHECKPOINT_RESTORE |
b8f566b0 PE |
248 | static int pid_ns_ctl_handler(struct ctl_table *table, int write, |
249 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
250 | { | |
49f4d8b9 | 251 | struct pid_namespace *pid_ns = task_active_pid_ns(current); |
b8f566b0 PE |
252 | struct ctl_table tmp = *table; |
253 | ||
49f4d8b9 | 254 | if (write && !ns_capable(pid_ns->user_ns, CAP_SYS_ADMIN)) |
b8f566b0 PE |
255 | return -EPERM; |
256 | ||
257 | /* | |
258 | * Writing directly to ns' last_pid field is OK, since this field | |
259 | * is volatile in a living namespace anyway and a code writing to | |
260 | * it should synchronize its usage with external means. | |
261 | */ | |
262 | ||
49f4d8b9 | 263 | tmp.data = &pid_ns->last_pid; |
579035dc | 264 | return proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos); |
b8f566b0 PE |
265 | } |
266 | ||
579035dc AV |
267 | extern int pid_max; |
268 | static int zero = 0; | |
b8f566b0 PE |
269 | static struct ctl_table pid_ns_ctl_table[] = { |
270 | { | |
271 | .procname = "ns_last_pid", | |
272 | .maxlen = sizeof(int), | |
273 | .mode = 0666, /* permissions are checked in the handler */ | |
274 | .proc_handler = pid_ns_ctl_handler, | |
579035dc AV |
275 | .extra1 = &zero, |
276 | .extra2 = &pid_max, | |
b8f566b0 PE |
277 | }, |
278 | { } | |
279 | }; | |
b8f566b0 | 280 | static struct ctl_path kern_path[] = { { .procname = "kernel", }, { } }; |
98ed57ee | 281 | #endif /* CONFIG_CHECKPOINT_RESTORE */ |
b8f566b0 | 282 | |
cf3f8921 DL |
283 | int reboot_pid_ns(struct pid_namespace *pid_ns, int cmd) |
284 | { | |
285 | if (pid_ns == &init_pid_ns) | |
286 | return 0; | |
287 | ||
288 | switch (cmd) { | |
289 | case LINUX_REBOOT_CMD_RESTART2: | |
290 | case LINUX_REBOOT_CMD_RESTART: | |
291 | pid_ns->reboot = SIGHUP; | |
292 | break; | |
293 | ||
294 | case LINUX_REBOOT_CMD_POWER_OFF: | |
295 | case LINUX_REBOOT_CMD_HALT: | |
296 | pid_ns->reboot = SIGINT; | |
297 | break; | |
298 | default: | |
299 | return -EINVAL; | |
300 | } | |
301 | ||
302 | read_lock(&tasklist_lock); | |
303 | force_sig(SIGKILL, pid_ns->child_reaper); | |
304 | read_unlock(&tasklist_lock); | |
305 | ||
306 | do_exit(0); | |
307 | ||
308 | /* Not reached */ | |
309 | return 0; | |
310 | } | |
311 | ||
57e8391d EB |
312 | static void *pidns_get(struct task_struct *task) |
313 | { | |
314 | struct pid_namespace *ns; | |
315 | ||
316 | rcu_read_lock(); | |
317 | ns = get_pid_ns(task_active_pid_ns(task)); | |
318 | rcu_read_unlock(); | |
319 | ||
320 | return ns; | |
321 | } | |
322 | ||
323 | static void pidns_put(void *ns) | |
324 | { | |
325 | put_pid_ns(ns); | |
326 | } | |
327 | ||
328 | static int pidns_install(struct nsproxy *nsproxy, void *ns) | |
329 | { | |
330 | struct pid_namespace *active = task_active_pid_ns(current); | |
331 | struct pid_namespace *ancestor, *new = ns; | |
332 | ||
5e4a0847 EB |
333 | if (!ns_capable(new->user_ns, CAP_SYS_ADMIN) || |
334 | !nsown_capable(CAP_SYS_ADMIN)) | |
57e8391d EB |
335 | return -EPERM; |
336 | ||
337 | /* | |
338 | * Only allow entering the current active pid namespace | |
339 | * or a child of the current active pid namespace. | |
340 | * | |
341 | * This is required for fork to return a usable pid value and | |
342 | * this maintains the property that processes and their | |
343 | * children can not escape their current pid namespace. | |
344 | */ | |
345 | if (new->level < active->level) | |
346 | return -EINVAL; | |
347 | ||
348 | ancestor = new; | |
349 | while (ancestor->level > active->level) | |
350 | ancestor = ancestor->parent; | |
351 | if (ancestor != active) | |
352 | return -EINVAL; | |
353 | ||
354 | put_pid_ns(nsproxy->pid_ns); | |
355 | nsproxy->pid_ns = get_pid_ns(new); | |
356 | return 0; | |
357 | } | |
358 | ||
98f842e6 EB |
359 | static unsigned int pidns_inum(void *ns) |
360 | { | |
361 | struct pid_namespace *pid_ns = ns; | |
362 | return pid_ns->proc_inum; | |
363 | } | |
364 | ||
57e8391d EB |
365 | const struct proc_ns_operations pidns_operations = { |
366 | .name = "pid", | |
367 | .type = CLONE_NEWPID, | |
368 | .get = pidns_get, | |
369 | .put = pidns_put, | |
370 | .install = pidns_install, | |
98f842e6 | 371 | .inum = pidns_inum, |
57e8391d EB |
372 | }; |
373 | ||
74bd59bb PE |
374 | static __init int pid_namespaces_init(void) |
375 | { | |
376 | pid_ns_cachep = KMEM_CACHE(pid_namespace, SLAB_PANIC); | |
98ed57ee CG |
377 | |
378 | #ifdef CONFIG_CHECKPOINT_RESTORE | |
b8f566b0 | 379 | register_sysctl_paths(kern_path, pid_ns_ctl_table); |
98ed57ee | 380 | #endif |
74bd59bb PE |
381 | return 0; |
382 | } | |
383 | ||
384 | __initcall(pid_namespaces_init); |