Commit | Line | Data |
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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 | ||
110 | kref_init(&ns->kref); | |
74bd59bb | 111 | ns->level = level; |
ed469a63 | 112 | ns->parent = get_pid_ns(parent_pid_ns); |
49f4d8b9 | 113 | ns->user_ns = get_user_ns(user_ns); |
0a01f2cc | 114 | INIT_WORK(&ns->proc_work, proc_cleanup_work); |
74bd59bb PE |
115 | |
116 | set_bit(0, ns->pidmap[0].page); | |
117 | atomic_set(&ns->pidmap[0].nr_free, BITS_PER_PAGE - 1); | |
118 | ||
84406c15 | 119 | for (i = 1; i < PIDMAP_ENTRIES; i++) |
74bd59bb | 120 | atomic_set(&ns->pidmap[i].nr_free, BITS_PER_PAGE); |
74bd59bb PE |
121 | |
122 | return ns; | |
123 | ||
124 | out_free_map: | |
125 | kfree(ns->pidmap[0].page); | |
126 | out_free: | |
127 | kmem_cache_free(pid_ns_cachep, ns); | |
128 | out: | |
4308eebb | 129 | return ERR_PTR(err); |
74bd59bb PE |
130 | } |
131 | ||
132 | static void destroy_pid_namespace(struct pid_namespace *ns) | |
133 | { | |
134 | int i; | |
135 | ||
136 | for (i = 0; i < PIDMAP_ENTRIES; i++) | |
137 | kfree(ns->pidmap[i].page); | |
49f4d8b9 | 138 | put_user_ns(ns->user_ns); |
74bd59bb PE |
139 | kmem_cache_free(pid_ns_cachep, ns); |
140 | } | |
141 | ||
49f4d8b9 EB |
142 | struct pid_namespace *copy_pid_ns(unsigned long flags, |
143 | struct user_namespace *user_ns, struct pid_namespace *old_ns) | |
74bd59bb | 144 | { |
74bd59bb | 145 | if (!(flags & CLONE_NEWPID)) |
dca4a979 | 146 | return get_pid_ns(old_ns); |
e5a47386 | 147 | if (flags & (CLONE_THREAD|CLONE_PARENT)) |
dca4a979 | 148 | return ERR_PTR(-EINVAL); |
49f4d8b9 | 149 | return create_pid_namespace(user_ns, old_ns); |
74bd59bb PE |
150 | } |
151 | ||
bbc2e3ef | 152 | static void free_pid_ns(struct kref *kref) |
74bd59bb | 153 | { |
bbc2e3ef | 154 | struct pid_namespace *ns; |
74bd59bb PE |
155 | |
156 | ns = container_of(kref, struct pid_namespace, kref); | |
74bd59bb | 157 | destroy_pid_namespace(ns); |
bbc2e3ef | 158 | } |
74bd59bb | 159 | |
bbc2e3ef CG |
160 | void put_pid_ns(struct pid_namespace *ns) |
161 | { | |
162 | struct pid_namespace *parent; | |
163 | ||
164 | while (ns != &init_pid_ns) { | |
165 | parent = ns->parent; | |
166 | if (!kref_put(&ns->kref, free_pid_ns)) | |
167 | break; | |
168 | ns = parent; | |
169 | } | |
74bd59bb | 170 | } |
bbc2e3ef | 171 | EXPORT_SYMBOL_GPL(put_pid_ns); |
74bd59bb PE |
172 | |
173 | void zap_pid_ns_processes(struct pid_namespace *pid_ns) | |
174 | { | |
175 | int nr; | |
176 | int rc; | |
00c10bc1 EB |
177 | struct task_struct *task, *me = current; |
178 | ||
179 | /* Ignore SIGCHLD causing any terminated children to autoreap */ | |
180 | spin_lock_irq(&me->sighand->siglock); | |
181 | me->sighand->action[SIGCHLD - 1].sa.sa_handler = SIG_IGN; | |
182 | spin_unlock_irq(&me->sighand->siglock); | |
74bd59bb PE |
183 | |
184 | /* | |
185 | * The last thread in the cgroup-init thread group is terminating. | |
186 | * Find remaining pid_ts in the namespace, signal and wait for them | |
187 | * to exit. | |
188 | * | |
189 | * Note: This signals each threads in the namespace - even those that | |
190 | * belong to the same thread group, To avoid this, we would have | |
191 | * to walk the entire tasklist looking a processes in this | |
192 | * namespace, but that could be unnecessarily expensive if the | |
193 | * pid namespace has just a few processes. Or we need to | |
194 | * maintain a tasklist for each pid namespace. | |
195 | * | |
196 | */ | |
197 | read_lock(&tasklist_lock); | |
198 | nr = next_pidmap(pid_ns, 1); | |
199 | while (nr > 0) { | |
e4da026f SB |
200 | rcu_read_lock(); |
201 | ||
e4da026f | 202 | task = pid_task(find_vpid(nr), PIDTYPE_PID); |
a02d6fd6 ON |
203 | if (task && !__fatal_signal_pending(task)) |
204 | send_sig_info(SIGKILL, SEND_SIG_FORCED, task); | |
e4da026f SB |
205 | |
206 | rcu_read_unlock(); | |
207 | ||
74bd59bb PE |
208 | nr = next_pidmap(pid_ns, nr); |
209 | } | |
210 | read_unlock(&tasklist_lock); | |
211 | ||
6347e900 | 212 | /* Firstly reap the EXIT_ZOMBIE children we may have. */ |
74bd59bb PE |
213 | do { |
214 | clear_thread_flag(TIF_SIGPENDING); | |
215 | rc = sys_wait4(-1, NULL, __WALL, NULL); | |
216 | } while (rc != -ECHILD); | |
217 | ||
6347e900 EB |
218 | /* |
219 | * sys_wait4() above can't reap the TASK_DEAD children. | |
af4b8a83 | 220 | * Make sure they all go away, see free_pid(). |
6347e900 EB |
221 | */ |
222 | for (;;) { | |
af4b8a83 EB |
223 | set_current_state(TASK_UNINTERRUPTIBLE); |
224 | if (pid_ns->nr_hashed == 1) | |
6347e900 EB |
225 | break; |
226 | schedule(); | |
227 | } | |
af4b8a83 | 228 | __set_current_state(TASK_RUNNING); |
6347e900 | 229 | |
cf3f8921 DL |
230 | if (pid_ns->reboot) |
231 | current->signal->group_exit_code = pid_ns->reboot; | |
232 | ||
0b6b030f | 233 | acct_exit_ns(pid_ns); |
74bd59bb PE |
234 | return; |
235 | } | |
236 | ||
98ed57ee | 237 | #ifdef CONFIG_CHECKPOINT_RESTORE |
b8f566b0 PE |
238 | static int pid_ns_ctl_handler(struct ctl_table *table, int write, |
239 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
240 | { | |
49f4d8b9 | 241 | struct pid_namespace *pid_ns = task_active_pid_ns(current); |
b8f566b0 PE |
242 | struct ctl_table tmp = *table; |
243 | ||
49f4d8b9 | 244 | if (write && !ns_capable(pid_ns->user_ns, CAP_SYS_ADMIN)) |
b8f566b0 PE |
245 | return -EPERM; |
246 | ||
247 | /* | |
248 | * Writing directly to ns' last_pid field is OK, since this field | |
249 | * is volatile in a living namespace anyway and a code writing to | |
250 | * it should synchronize its usage with external means. | |
251 | */ | |
252 | ||
49f4d8b9 | 253 | tmp.data = &pid_ns->last_pid; |
579035dc | 254 | return proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos); |
b8f566b0 PE |
255 | } |
256 | ||
579035dc AV |
257 | extern int pid_max; |
258 | static int zero = 0; | |
b8f566b0 PE |
259 | static struct ctl_table pid_ns_ctl_table[] = { |
260 | { | |
261 | .procname = "ns_last_pid", | |
262 | .maxlen = sizeof(int), | |
263 | .mode = 0666, /* permissions are checked in the handler */ | |
264 | .proc_handler = pid_ns_ctl_handler, | |
579035dc AV |
265 | .extra1 = &zero, |
266 | .extra2 = &pid_max, | |
b8f566b0 PE |
267 | }, |
268 | { } | |
269 | }; | |
b8f566b0 | 270 | static struct ctl_path kern_path[] = { { .procname = "kernel", }, { } }; |
98ed57ee | 271 | #endif /* CONFIG_CHECKPOINT_RESTORE */ |
b8f566b0 | 272 | |
cf3f8921 DL |
273 | int reboot_pid_ns(struct pid_namespace *pid_ns, int cmd) |
274 | { | |
275 | if (pid_ns == &init_pid_ns) | |
276 | return 0; | |
277 | ||
278 | switch (cmd) { | |
279 | case LINUX_REBOOT_CMD_RESTART2: | |
280 | case LINUX_REBOOT_CMD_RESTART: | |
281 | pid_ns->reboot = SIGHUP; | |
282 | break; | |
283 | ||
284 | case LINUX_REBOOT_CMD_POWER_OFF: | |
285 | case LINUX_REBOOT_CMD_HALT: | |
286 | pid_ns->reboot = SIGINT; | |
287 | break; | |
288 | default: | |
289 | return -EINVAL; | |
290 | } | |
291 | ||
292 | read_lock(&tasklist_lock); | |
293 | force_sig(SIGKILL, pid_ns->child_reaper); | |
294 | read_unlock(&tasklist_lock); | |
295 | ||
296 | do_exit(0); | |
297 | ||
298 | /* Not reached */ | |
299 | return 0; | |
300 | } | |
301 | ||
74bd59bb PE |
302 | static __init int pid_namespaces_init(void) |
303 | { | |
304 | pid_ns_cachep = KMEM_CACHE(pid_namespace, SLAB_PANIC); | |
98ed57ee CG |
305 | |
306 | #ifdef CONFIG_CHECKPOINT_RESTORE | |
b8f566b0 | 307 | register_sysctl_paths(kern_path, pid_ns_ctl_table); |
98ed57ee | 308 | #endif |
74bd59bb PE |
309 | return 0; |
310 | } | |
311 | ||
312 | __initcall(pid_namespaces_init); |