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Source at commit fbf123cd4cc0c097fe9a99c90109ebb2a5e94a50 created 10 years 3 months ago. By Lars-Peter Clausen, dma: jz4740: Dequeue descriptor from active list before completing it | |
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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> |
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> |
21 | |
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 | |
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 | |
79 | /* MAX_PID_NS_LEVEL is needed for limiting size of 'struct pid' */ |
80 | #define MAX_PID_NS_LEVEL 32 |
81 | |
82 | static struct pid_namespace *create_pid_namespace(struct user_namespace *user_ns, |
83 | struct pid_namespace *parent_pid_ns) |
84 | { |
85 | struct pid_namespace *ns; |
86 | unsigned int level = parent_pid_ns->level + 1; |
87 | int i; |
88 | int err; |
89 | |
90 | if (level > MAX_PID_NS_LEVEL) { |
91 | err = -EINVAL; |
92 | goto out; |
93 | } |
94 | |
95 | err = -ENOMEM; |
96 | ns = kmem_cache_zalloc(pid_ns_cachep, GFP_KERNEL); |
97 | if (ns == NULL) |
98 | goto out; |
99 | |
100 | ns->pidmap[0].page = kzalloc(PAGE_SIZE, GFP_KERNEL); |
101 | if (!ns->pidmap[0].page) |
102 | goto out_free; |
103 | |
104 | ns->pid_cachep = create_pid_cachep(level + 1); |
105 | if (ns->pid_cachep == NULL) |
106 | goto out_free_map; |
107 | |
108 | err = proc_alloc_inum(&ns->proc_inum); |
109 | if (err) |
110 | goto out_free_map; |
111 | |
112 | kref_init(&ns->kref); |
113 | ns->level = level; |
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); |
118 | |
119 | set_bit(0, ns->pidmap[0].page); |
120 | atomic_set(&ns->pidmap[0].nr_free, BITS_PER_PAGE - 1); |
121 | |
122 | for (i = 1; i < PIDMAP_ENTRIES; i++) |
123 | atomic_set(&ns->pidmap[i].nr_free, BITS_PER_PAGE); |
124 | |
125 | return ns; |
126 | |
127 | out_free_map: |
128 | kfree(ns->pidmap[0].page); |
129 | out_free: |
130 | kmem_cache_free(pid_ns_cachep, ns); |
131 | out: |
132 | return ERR_PTR(err); |
133 | } |
134 | |
135 | static void delayed_free_pidns(struct rcu_head *p) |
136 | { |
137 | kmem_cache_free(pid_ns_cachep, |
138 | container_of(p, struct pid_namespace, rcu)); |
139 | } |
140 | |
141 | static void destroy_pid_namespace(struct pid_namespace *ns) |
142 | { |
143 | int i; |
144 | |
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); |
150 | } |
151 | |
152 | struct pid_namespace *copy_pid_ns(unsigned long flags, |
153 | struct user_namespace *user_ns, struct pid_namespace *old_ns) |
154 | { |
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); |
160 | } |
161 | |
162 | static void free_pid_ns(struct kref *kref) |
163 | { |
164 | struct pid_namespace *ns; |
165 | |
166 | ns = container_of(kref, struct pid_namespace, kref); |
167 | destroy_pid_namespace(ns); |
168 | } |
169 | |
170 | void put_pid_ns(struct pid_namespace *ns) |
171 | { |
172 | struct pid_namespace *parent; |
173 | |
174 | while (ns != &init_pid_ns) { |
175 | parent = ns->parent; |
176 | if (!kref_put(&ns->kref, free_pid_ns)) |
177 | break; |
178 | ns = parent; |
179 | } |
180 | } |
181 | EXPORT_SYMBOL_GPL(put_pid_ns); |
182 | |
183 | void zap_pid_ns_processes(struct pid_namespace *pid_ns) |
184 | { |
185 | int nr; |
186 | int rc; |
187 | struct task_struct *task, *me = current; |
188 | int init_pids = thread_group_leader(me) ? 1 : 2; |
189 | |
190 | /* Don't allow any more processes into the pid namespace */ |
191 | disable_pid_allocation(pid_ns); |
192 | |
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); |
197 | |
198 | /* |
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 |
201 | * to exit. |
202 | * |
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. |
209 | * |
210 | */ |
211 | read_lock(&tasklist_lock); |
212 | nr = next_pidmap(pid_ns, 1); |
213 | while (nr > 0) { |
214 | rcu_read_lock(); |
215 | |
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); |
219 | |
220 | rcu_read_unlock(); |
221 | |
222 | nr = next_pidmap(pid_ns, nr); |
223 | } |
224 | read_unlock(&tasklist_lock); |
225 | |
226 | /* Firstly reap the EXIT_ZOMBIE children we may have. */ |
227 | do { |
228 | clear_thread_flag(TIF_SIGPENDING); |
229 | rc = sys_wait4(-1, NULL, __WALL, NULL); |
230 | } while (rc != -ECHILD); |
231 | |
232 | /* |
233 | * sys_wait4() above can't reap the TASK_DEAD children. |
234 | * Make sure they all go away, see free_pid(). |
235 | */ |
236 | for (;;) { |
237 | set_current_state(TASK_UNINTERRUPTIBLE); |
238 | if (pid_ns->nr_hashed == init_pids) |
239 | break; |
240 | schedule(); |
241 | } |
242 | __set_current_state(TASK_RUNNING); |
243 | |
244 | if (pid_ns->reboot) |
245 | current->signal->group_exit_code = pid_ns->reboot; |
246 | |
247 | acct_exit_ns(pid_ns); |
248 | return; |
249 | } |
250 | |
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) |
254 | { |
255 | struct pid_namespace *pid_ns = task_active_pid_ns(current); |
256 | struct ctl_table tmp = *table; |
257 | |
258 | if (write && !ns_capable(pid_ns->user_ns, CAP_SYS_ADMIN)) |
259 | return -EPERM; |
260 | |
261 | /* |
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. |
265 | */ |
266 | |
267 | tmp.data = &pid_ns->last_pid; |
268 | return proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos); |
269 | } |
270 | |
271 | extern int pid_max; |
272 | static int zero = 0; |
273 | static struct ctl_table pid_ns_ctl_table[] = { |
274 | { |
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, |
279 | .extra1 = &zero, |
280 | .extra2 = &pid_max, |
281 | }, |
282 | { } |
283 | }; |
284 | static struct ctl_path kern_path[] = { { .procname = "kernel", }, { } }; |
285 | #endif /* CONFIG_CHECKPOINT_RESTORE */ |
286 | |
287 | int reboot_pid_ns(struct pid_namespace *pid_ns, int cmd) |
288 | { |
289 | if (pid_ns == &init_pid_ns) |
290 | return 0; |
291 | |
292 | switch (cmd) { |
293 | case LINUX_REBOOT_CMD_RESTART2: |
294 | case LINUX_REBOOT_CMD_RESTART: |
295 | pid_ns->reboot = SIGHUP; |
296 | break; |
297 | |
298 | case LINUX_REBOOT_CMD_POWER_OFF: |
299 | case LINUX_REBOOT_CMD_HALT: |
300 | pid_ns->reboot = SIGINT; |
301 | break; |
302 | default: |
303 | return -EINVAL; |
304 | } |
305 | |
306 | read_lock(&tasklist_lock); |
307 | force_sig(SIGKILL, pid_ns->child_reaper); |
308 | read_unlock(&tasklist_lock); |
309 | |
310 | do_exit(0); |
311 | |
312 | /* Not reached */ |
313 | return 0; |
314 | } |
315 | |
316 | static void *pidns_get(struct task_struct *task) |
317 | { |
318 | struct pid_namespace *ns; |
319 | |
320 | rcu_read_lock(); |
321 | ns = task_active_pid_ns(task); |
322 | if (ns) |
323 | get_pid_ns(ns); |
324 | rcu_read_unlock(); |
325 | |
326 | return ns; |
327 | } |
328 | |
329 | static void pidns_put(void *ns) |
330 | { |
331 | put_pid_ns(ns); |
332 | } |
333 | |
334 | static int pidns_install(struct nsproxy *nsproxy, void *ns) |
335 | { |
336 | struct pid_namespace *active = task_active_pid_ns(current); |
337 | struct pid_namespace *ancestor, *new = ns; |
338 | |
339 | if (!ns_capable(new->user_ns, CAP_SYS_ADMIN) || |
340 | !ns_capable(current_user_ns(), CAP_SYS_ADMIN)) |
341 | return -EPERM; |
342 | |
343 | /* |
344 | * Only allow entering the current active pid namespace |
345 | * or a child of the current active pid namespace. |
346 | * |
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. |
350 | */ |
351 | if (new->level < active->level) |
352 | return -EINVAL; |
353 | |
354 | ancestor = new; |
355 | while (ancestor->level > active->level) |
356 | ancestor = ancestor->parent; |
357 | if (ancestor != active) |
358 | return -EINVAL; |
359 | |
360 | put_pid_ns(nsproxy->pid_ns_for_children); |
361 | nsproxy->pid_ns_for_children = get_pid_ns(new); |
362 | return 0; |
363 | } |
364 | |
365 | static unsigned int pidns_inum(void *ns) |
366 | { |
367 | struct pid_namespace *pid_ns = ns; |
368 | return pid_ns->proc_inum; |
369 | } |
370 | |
371 | const struct proc_ns_operations pidns_operations = { |
372 | .name = "pid", |
373 | .type = CLONE_NEWPID, |
374 | .get = pidns_get, |
375 | .put = pidns_put, |
376 | .install = pidns_install, |
377 | .inum = pidns_inum, |
378 | }; |
379 | |
380 | static __init int pid_namespaces_init(void) |
381 | { |
382 | pid_ns_cachep = KMEM_CACHE(pid_namespace, SLAB_PANIC); |
383 | |
384 | #ifdef CONFIG_CHECKPOINT_RESTORE |
385 | register_sysctl_paths(kern_path, pid_ns_ctl_table); |
386 | #endif |
387 | return 0; |
388 | } |
389 | |
390 | __initcall(pid_namespaces_init); |
391 |
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