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
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_fs.h>
19 #include <linux/reboot.h>
20 #include <linux/export.h>
22 #define BITS_PER_PAGE (PAGE_SIZE*8)
27 struct kmem_cache
*cachep
;
28 struct list_head list
;
31 static LIST_HEAD(pid_caches_lh
);
32 static DEFINE_MUTEX(pid_caches_mutex
);
33 static struct kmem_cache
*pid_ns_cachep
;
36 * creates the kmem cache to allocate pids from.
37 * @nr_ids: the number of numerical ids this pid will have to carry
40 static struct kmem_cache
*create_pid_cachep(int nr_ids
)
42 struct pid_cache
*pcache
;
43 struct kmem_cache
*cachep
;
45 mutex_lock(&pid_caches_mutex
);
46 list_for_each_entry(pcache
, &pid_caches_lh
, list
)
47 if (pcache
->nr_ids
== nr_ids
)
50 pcache
= kmalloc(sizeof(struct pid_cache
), GFP_KERNEL
);
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
);
61 pcache
->nr_ids
= nr_ids
;
62 pcache
->cachep
= cachep
;
63 list_add(&pcache
->list
, &pid_caches_lh
);
65 mutex_unlock(&pid_caches_mutex
);
66 return pcache
->cachep
;
71 mutex_unlock(&pid_caches_mutex
);
75 static void proc_cleanup_work(struct work_struct
*work
)
77 struct pid_namespace
*ns
= container_of(work
, struct pid_namespace
, proc_work
);
78 pid_ns_release_proc(ns
);
81 /* MAX_PID_NS_LEVEL is needed for limiting size of 'struct pid' */
82 #define MAX_PID_NS_LEVEL 32
84 static struct pid_namespace
*create_pid_namespace(struct user_namespace
*user_ns
,
85 struct pid_namespace
*parent_pid_ns
)
87 struct pid_namespace
*ns
;
88 unsigned int level
= parent_pid_ns
->level
+ 1;
92 if (level
> MAX_PID_NS_LEVEL
) {
98 ns
= kmem_cache_zalloc(pid_ns_cachep
, GFP_KERNEL
);
102 ns
->pidmap
[0].page
= kzalloc(PAGE_SIZE
, GFP_KERNEL
);
103 if (!ns
->pidmap
[0].page
)
106 ns
->pid_cachep
= create_pid_cachep(level
+ 1);
107 if (ns
->pid_cachep
== NULL
)
110 err
= proc_alloc_inum(&ns
->proc_inum
);
114 kref_init(&ns
->kref
);
116 ns
->parent
= get_pid_ns(parent_pid_ns
);
117 ns
->user_ns
= get_user_ns(user_ns
);
118 INIT_WORK(&ns
->proc_work
, proc_cleanup_work
);
120 set_bit(0, ns
->pidmap
[0].page
);
121 atomic_set(&ns
->pidmap
[0].nr_free
, BITS_PER_PAGE
- 1);
123 for (i
= 1; i
< PIDMAP_ENTRIES
; i
++)
124 atomic_set(&ns
->pidmap
[i
].nr_free
, BITS_PER_PAGE
);
129 kfree(ns
->pidmap
[0].page
);
131 kmem_cache_free(pid_ns_cachep
, ns
);
136 static void destroy_pid_namespace(struct pid_namespace
*ns
)
140 proc_free_inum(ns
->proc_inum
);
141 for (i
= 0; i
< PIDMAP_ENTRIES
; i
++)
142 kfree(ns
->pidmap
[i
].page
);
143 put_user_ns(ns
->user_ns
);
144 kmem_cache_free(pid_ns_cachep
, ns
);
147 struct pid_namespace
*copy_pid_ns(unsigned long flags
,
148 struct user_namespace
*user_ns
, struct pid_namespace
*old_ns
)
150 if (!(flags
& CLONE_NEWPID
))
151 return get_pid_ns(old_ns
);
152 if (task_active_pid_ns(current
) != old_ns
)
153 return ERR_PTR(-EINVAL
);
154 return create_pid_namespace(user_ns
, old_ns
);
157 static void free_pid_ns(struct kref
*kref
)
159 struct pid_namespace
*ns
;
161 ns
= container_of(kref
, struct pid_namespace
, kref
);
162 destroy_pid_namespace(ns
);
165 void put_pid_ns(struct pid_namespace
*ns
)
167 struct pid_namespace
*parent
;
169 while (ns
!= &init_pid_ns
) {
171 if (!kref_put(&ns
->kref
, free_pid_ns
))
176 EXPORT_SYMBOL_GPL(put_pid_ns
);
178 void zap_pid_ns_processes(struct pid_namespace
*pid_ns
)
182 struct task_struct
*task
, *me
= current
;
184 /* Ignore SIGCHLD causing any terminated children to autoreap */
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
);
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
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.
202 read_lock(&tasklist_lock
);
203 nr
= next_pidmap(pid_ns
, 1);
207 task
= pid_task(find_vpid(nr
), PIDTYPE_PID
);
208 if (task
&& !__fatal_signal_pending(task
))
209 send_sig_info(SIGKILL
, SEND_SIG_FORCED
, task
);
213 nr
= next_pidmap(pid_ns
, nr
);
215 read_unlock(&tasklist_lock
);
217 /* Firstly reap the EXIT_ZOMBIE children we may have. */
219 clear_thread_flag(TIF_SIGPENDING
);
220 rc
= sys_wait4(-1, NULL
, __WALL
, NULL
);
221 } while (rc
!= -ECHILD
);
224 * sys_wait4() above can't reap the TASK_DEAD children.
225 * Make sure they all go away, see free_pid().
228 set_current_state(TASK_UNINTERRUPTIBLE
);
229 if (pid_ns
->nr_hashed
== 1)
233 __set_current_state(TASK_RUNNING
);
236 current
->signal
->group_exit_code
= pid_ns
->reboot
;
238 acct_exit_ns(pid_ns
);
242 #ifdef CONFIG_CHECKPOINT_RESTORE
243 static int pid_ns_ctl_handler(struct ctl_table
*table
, int write
,
244 void __user
*buffer
, size_t *lenp
, loff_t
*ppos
)
246 struct pid_namespace
*pid_ns
= task_active_pid_ns(current
);
247 struct ctl_table tmp
= *table
;
249 if (write
&& !ns_capable(pid_ns
->user_ns
, CAP_SYS_ADMIN
))
253 * Writing directly to ns' last_pid field is OK, since this field
254 * is volatile in a living namespace anyway and a code writing to
255 * it should synchronize its usage with external means.
258 tmp
.data
= &pid_ns
->last_pid
;
259 return proc_dointvec_minmax(&tmp
, write
, buffer
, lenp
, ppos
);
264 static struct ctl_table pid_ns_ctl_table
[] = {
266 .procname
= "ns_last_pid",
267 .maxlen
= sizeof(int),
268 .mode
= 0666, /* permissions are checked in the handler */
269 .proc_handler
= pid_ns_ctl_handler
,
275 static struct ctl_path kern_path
[] = { { .procname
= "kernel", }, { } };
276 #endif /* CONFIG_CHECKPOINT_RESTORE */
278 int reboot_pid_ns(struct pid_namespace
*pid_ns
, int cmd
)
280 if (pid_ns
== &init_pid_ns
)
284 case LINUX_REBOOT_CMD_RESTART2
:
285 case LINUX_REBOOT_CMD_RESTART
:
286 pid_ns
->reboot
= SIGHUP
;
289 case LINUX_REBOOT_CMD_POWER_OFF
:
290 case LINUX_REBOOT_CMD_HALT
:
291 pid_ns
->reboot
= SIGINT
;
297 read_lock(&tasklist_lock
);
298 force_sig(SIGKILL
, pid_ns
->child_reaper
);
299 read_unlock(&tasklist_lock
);
307 static void *pidns_get(struct task_struct
*task
)
309 struct pid_namespace
*ns
;
312 ns
= get_pid_ns(task_active_pid_ns(task
));
318 static void pidns_put(void *ns
)
323 static int pidns_install(struct nsproxy
*nsproxy
, void *ns
)
325 struct pid_namespace
*active
= task_active_pid_ns(current
);
326 struct pid_namespace
*ancestor
, *new = ns
;
328 if (!ns_capable(new->user_ns
, CAP_SYS_ADMIN
) ||
329 !nsown_capable(CAP_SYS_ADMIN
))
333 * Only allow entering the current active pid namespace
334 * or a child of the current active pid namespace.
336 * This is required for fork to return a usable pid value and
337 * this maintains the property that processes and their
338 * children can not escape their current pid namespace.
340 if (new->level
< active
->level
)
344 while (ancestor
->level
> active
->level
)
345 ancestor
= ancestor
->parent
;
346 if (ancestor
!= active
)
349 put_pid_ns(nsproxy
->pid_ns
);
350 nsproxy
->pid_ns
= get_pid_ns(new);
354 static unsigned int pidns_inum(void *ns
)
356 struct pid_namespace
*pid_ns
= ns
;
357 return pid_ns
->proc_inum
;
360 const struct proc_ns_operations pidns_operations
= {
362 .type
= CLONE_NEWPID
,
365 .install
= pidns_install
,
369 static __init
int pid_namespaces_init(void)
371 pid_ns_cachep
= KMEM_CACHE(pid_namespace
, SLAB_PANIC
);
373 #ifdef CONFIG_CHECKPOINT_RESTORE
374 register_sysctl_paths(kern_path
, pid_ns_ctl_table
);
379 __initcall(pid_namespaces_init
);