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/syscalls.h>
14 #include <linux/err.h>
15 #include <linux/acct.h>
16 #include <linux/slab.h>
17 #include <linux/proc_fs.h>
19 #define BITS_PER_PAGE (PAGE_SIZE*8)
24 struct kmem_cache
*cachep
;
25 struct list_head list
;
28 static LIST_HEAD(pid_caches_lh
);
29 static DEFINE_MUTEX(pid_caches_mutex
);
30 static struct kmem_cache
*pid_ns_cachep
;
33 * creates the kmem cache to allocate pids from.
34 * @nr_ids: the number of numerical ids this pid will have to carry
37 static struct kmem_cache
*create_pid_cachep(int nr_ids
)
39 struct pid_cache
*pcache
;
40 struct kmem_cache
*cachep
;
42 mutex_lock(&pid_caches_mutex
);
43 list_for_each_entry(pcache
, &pid_caches_lh
, list
)
44 if (pcache
->nr_ids
== nr_ids
)
47 pcache
= kmalloc(sizeof(struct pid_cache
), GFP_KERNEL
);
51 snprintf(pcache
->name
, sizeof(pcache
->name
), "pid_%d", nr_ids
);
52 cachep
= kmem_cache_create(pcache
->name
,
53 sizeof(struct pid
) + (nr_ids
- 1) * sizeof(struct upid
),
54 0, SLAB_HWCACHE_ALIGN
, NULL
);
58 pcache
->nr_ids
= nr_ids
;
59 pcache
->cachep
= cachep
;
60 list_add(&pcache
->list
, &pid_caches_lh
);
62 mutex_unlock(&pid_caches_mutex
);
63 return pcache
->cachep
;
68 mutex_unlock(&pid_caches_mutex
);
72 static struct pid_namespace
*create_pid_namespace(struct pid_namespace
*parent_pid_ns
)
74 struct pid_namespace
*ns
;
75 unsigned int level
= parent_pid_ns
->level
+ 1;
78 ns
= kmem_cache_zalloc(pid_ns_cachep
, GFP_KERNEL
);
82 ns
->pidmap
[0].page
= kzalloc(PAGE_SIZE
, GFP_KERNEL
);
83 if (!ns
->pidmap
[0].page
)
86 ns
->pid_cachep
= create_pid_cachep(level
+ 1);
87 if (ns
->pid_cachep
== NULL
)
92 ns
->parent
= get_pid_ns(parent_pid_ns
);
94 set_bit(0, ns
->pidmap
[0].page
);
95 atomic_set(&ns
->pidmap
[0].nr_free
, BITS_PER_PAGE
- 1);
97 for (i
= 1; i
< PIDMAP_ENTRIES
; i
++)
98 atomic_set(&ns
->pidmap
[i
].nr_free
, BITS_PER_PAGE
);
100 err
= pid_ns_prepare_proc(ns
);
102 goto out_put_parent_pid_ns
;
106 out_put_parent_pid_ns
:
107 put_pid_ns(parent_pid_ns
);
109 kfree(ns
->pidmap
[0].page
);
111 kmem_cache_free(pid_ns_cachep
, ns
);
116 static void destroy_pid_namespace(struct pid_namespace
*ns
)
120 for (i
= 0; i
< PIDMAP_ENTRIES
; i
++)
121 kfree(ns
->pidmap
[i
].page
);
122 kmem_cache_free(pid_ns_cachep
, ns
);
125 struct pid_namespace
*copy_pid_ns(unsigned long flags
, struct pid_namespace
*old_ns
)
127 if (!(flags
& CLONE_NEWPID
))
128 return get_pid_ns(old_ns
);
129 if (flags
& (CLONE_THREAD
|CLONE_PARENT
))
130 return ERR_PTR(-EINVAL
);
131 return create_pid_namespace(old_ns
);
134 void free_pid_ns(struct kref
*kref
)
136 struct pid_namespace
*ns
, *parent
;
138 ns
= container_of(kref
, struct pid_namespace
, kref
);
141 destroy_pid_namespace(ns
);
147 void zap_pid_ns_processes(struct pid_namespace
*pid_ns
)
151 struct task_struct
*task
;
154 * The last thread in the cgroup-init thread group is terminating.
155 * Find remaining pid_ts in the namespace, signal and wait for them
158 * Note: This signals each threads in the namespace - even those that
159 * belong to the same thread group, To avoid this, we would have
160 * to walk the entire tasklist looking a processes in this
161 * namespace, but that could be unnecessarily expensive if the
162 * pid namespace has just a few processes. Or we need to
163 * maintain a tasklist for each pid namespace.
166 read_lock(&tasklist_lock
);
167 nr
= next_pidmap(pid_ns
, 1);
172 * Any nested-container's init processes won't ignore the
173 * SEND_SIG_NOINFO signal, see send_signal()->si_fromuser().
175 task
= pid_task(find_vpid(nr
), PIDTYPE_PID
);
177 send_sig_info(SIGKILL
, SEND_SIG_NOINFO
, task
);
181 nr
= next_pidmap(pid_ns
, nr
);
183 read_unlock(&tasklist_lock
);
186 clear_thread_flag(TIF_SIGPENDING
);
187 rc
= sys_wait4(-1, NULL
, __WALL
, NULL
);
188 } while (rc
!= -ECHILD
);
190 acct_exit_ns(pid_ns
);
194 static __init
int pid_namespaces_init(void)
196 pid_ns_cachep
= KMEM_CACHE(pid_namespace
, SLAB_PANIC
);
200 __initcall(pid_namespaces_init
);
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