blob: 86b3796b0436726e5b0208021cc990bfdc7044e2 [file] [log] [blame]
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -08001/*
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/syscalls.h>
14#include <linux/err.h>
Pavel Emelyanov0b6b0302008-07-25 01:48:47 -070015#include <linux/acct.h>
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -080016
17#define BITS_PER_PAGE (PAGE_SIZE*8)
18
19struct pid_cache {
20 int nr_ids;
21 char name[16];
22 struct kmem_cache *cachep;
23 struct list_head list;
24};
25
26static LIST_HEAD(pid_caches_lh);
27static DEFINE_MUTEX(pid_caches_mutex);
28static struct kmem_cache *pid_ns_cachep;
29
30/*
31 * creates the kmem cache to allocate pids from.
32 * @nr_ids: the number of numerical ids this pid will have to carry
33 */
34
35static struct kmem_cache *create_pid_cachep(int nr_ids)
36{
37 struct pid_cache *pcache;
38 struct kmem_cache *cachep;
39
40 mutex_lock(&pid_caches_mutex);
41 list_for_each_entry(pcache, &pid_caches_lh, list)
42 if (pcache->nr_ids == nr_ids)
43 goto out;
44
45 pcache = kmalloc(sizeof(struct pid_cache), GFP_KERNEL);
46 if (pcache == NULL)
47 goto err_alloc;
48
49 snprintf(pcache->name, sizeof(pcache->name), "pid_%d", nr_ids);
50 cachep = kmem_cache_create(pcache->name,
51 sizeof(struct pid) + (nr_ids - 1) * sizeof(struct upid),
52 0, SLAB_HWCACHE_ALIGN, NULL);
53 if (cachep == NULL)
54 goto err_cachep;
55
56 pcache->nr_ids = nr_ids;
57 pcache->cachep = cachep;
58 list_add(&pcache->list, &pid_caches_lh);
59out:
60 mutex_unlock(&pid_caches_mutex);
61 return pcache->cachep;
62
63err_cachep:
64 kfree(pcache);
65err_alloc:
66 mutex_unlock(&pid_caches_mutex);
67 return NULL;
68}
69
Alexey Dobriyaned469a62009-06-17 16:27:52 -070070static struct pid_namespace *create_pid_namespace(struct pid_namespace *parent_pid_ns)
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -080071{
72 struct pid_namespace *ns;
Alexey Dobriyaned469a62009-06-17 16:27:52 -070073 unsigned int level = parent_pid_ns->level + 1;
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -080074 int i;
75
Pavel Emelyanov84406c12008-07-25 01:48:42 -070076 ns = kmem_cache_zalloc(pid_ns_cachep, GFP_KERNEL);
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -080077 if (ns == NULL)
78 goto out;
79
80 ns->pidmap[0].page = kzalloc(PAGE_SIZE, GFP_KERNEL);
81 if (!ns->pidmap[0].page)
82 goto out_free;
83
84 ns->pid_cachep = create_pid_cachep(level + 1);
85 if (ns->pid_cachep == NULL)
86 goto out_free_map;
87
88 kref_init(&ns->kref);
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -080089 ns->level = level;
Alexey Dobriyaned469a62009-06-17 16:27:52 -070090 ns->parent = get_pid_ns(parent_pid_ns);
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -080091
92 set_bit(0, ns->pidmap[0].page);
93 atomic_set(&ns->pidmap[0].nr_free, BITS_PER_PAGE - 1);
94
Pavel Emelyanov84406c12008-07-25 01:48:42 -070095 for (i = 1; i < PIDMAP_ENTRIES; i++)
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -080096 atomic_set(&ns->pidmap[i].nr_free, BITS_PER_PAGE);
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -080097
98 return ns;
99
100out_free_map:
101 kfree(ns->pidmap[0].page);
102out_free:
103 kmem_cache_free(pid_ns_cachep, ns);
104out:
105 return ERR_PTR(-ENOMEM);
106}
107
108static void destroy_pid_namespace(struct pid_namespace *ns)
109{
110 int i;
111
112 for (i = 0; i < PIDMAP_ENTRIES; i++)
113 kfree(ns->pidmap[i].page);
114 kmem_cache_free(pid_ns_cachep, ns);
115}
116
117struct pid_namespace *copy_pid_ns(unsigned long flags, struct pid_namespace *old_ns)
118{
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -0800119 if (!(flags & CLONE_NEWPID))
Alexey Dobriyandca4a972009-06-17 16:27:53 -0700120 return get_pid_ns(old_ns);
Sukadev Bhattiprolue5a47382009-09-23 15:57:22 -0700121 if (flags & (CLONE_THREAD|CLONE_PARENT))
Alexey Dobriyandca4a972009-06-17 16:27:53 -0700122 return ERR_PTR(-EINVAL);
123 return create_pid_namespace(old_ns);
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -0800124}
125
126void free_pid_ns(struct kref *kref)
127{
128 struct pid_namespace *ns, *parent;
129
130 ns = container_of(kref, struct pid_namespace, kref);
131
132 parent = ns->parent;
133 destroy_pid_namespace(ns);
134
135 if (parent != NULL)
136 put_pid_ns(parent);
137}
138
139void zap_pid_ns_processes(struct pid_namespace *pid_ns)
140{
141 int nr;
142 int rc;
Sukadev Bhattiprolue4da0262009-04-02 16:58:06 -0700143 struct task_struct *task;
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -0800144
145 /*
146 * The last thread in the cgroup-init thread group is terminating.
147 * Find remaining pid_ts in the namespace, signal and wait for them
148 * to exit.
149 *
150 * Note: This signals each threads in the namespace - even those that
151 * belong to the same thread group, To avoid this, we would have
152 * to walk the entire tasklist looking a processes in this
153 * namespace, but that could be unnecessarily expensive if the
154 * pid namespace has just a few processes. Or we need to
155 * maintain a tasklist for each pid namespace.
156 *
157 */
158 read_lock(&tasklist_lock);
159 nr = next_pidmap(pid_ns, 1);
160 while (nr > 0) {
Sukadev Bhattiprolue4da0262009-04-02 16:58:06 -0700161 rcu_read_lock();
162
163 /*
164 * Use force_sig() since it clears SIGNAL_UNKILLABLE ensuring
165 * any nested-container's init processes don't ignore the
166 * signal
167 */
168 task = pid_task(find_vpid(nr), PIDTYPE_PID);
169 if (task)
170 force_sig(SIGKILL, task);
171
172 rcu_read_unlock();
173
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -0800174 nr = next_pidmap(pid_ns, nr);
175 }
176 read_unlock(&tasklist_lock);
177
178 do {
179 clear_thread_flag(TIF_SIGPENDING);
180 rc = sys_wait4(-1, NULL, __WALL, NULL);
181 } while (rc != -ECHILD);
182
Pavel Emelyanov0b6b0302008-07-25 01:48:47 -0700183 acct_exit_ns(pid_ns);
Pavel Emelyanov74bd59b2008-02-08 04:18:24 -0800184 return;
185}
186
187static __init int pid_namespaces_init(void)
188{
189 pid_ns_cachep = KMEM_CACHE(pid_namespace, SLAB_PANIC);
190 return 0;
191}
192
193__initcall(pid_namespaces_init);