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Source at commit ec7cab4cbb721bff91ec924ec691efd8daf36579 created 12 years 8 months ago. By Maarten ter Huurne, MIPS: JZ4740: A320: Updated quickstart documentation. | |
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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/syscalls.h> |
14 | #include <linux/err.h> |
15 | #include <linux/acct.h> |
16 | #include <linux/slab.h> |
17 | #include <linux/proc_fs.h> |
18 | |
19 | #define BITS_PER_PAGE (PAGE_SIZE*8) |
20 | |
21 | struct pid_cache { |
22 | int nr_ids; |
23 | char name[16]; |
24 | struct kmem_cache *cachep; |
25 | struct list_head list; |
26 | }; |
27 | |
28 | static LIST_HEAD(pid_caches_lh); |
29 | static DEFINE_MUTEX(pid_caches_mutex); |
30 | static struct kmem_cache *pid_ns_cachep; |
31 | |
32 | /* |
33 | * creates the kmem cache to allocate pids from. |
34 | * @nr_ids: the number of numerical ids this pid will have to carry |
35 | */ |
36 | |
37 | static struct kmem_cache *create_pid_cachep(int nr_ids) |
38 | { |
39 | struct pid_cache *pcache; |
40 | struct kmem_cache *cachep; |
41 | |
42 | mutex_lock(&pid_caches_mutex); |
43 | list_for_each_entry(pcache, &pid_caches_lh, list) |
44 | if (pcache->nr_ids == nr_ids) |
45 | goto out; |
46 | |
47 | pcache = kmalloc(sizeof(struct pid_cache), GFP_KERNEL); |
48 | if (pcache == NULL) |
49 | goto err_alloc; |
50 | |
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); |
55 | if (cachep == NULL) |
56 | goto err_cachep; |
57 | |
58 | pcache->nr_ids = nr_ids; |
59 | pcache->cachep = cachep; |
60 | list_add(&pcache->list, &pid_caches_lh); |
61 | out: |
62 | mutex_unlock(&pid_caches_mutex); |
63 | return pcache->cachep; |
64 | |
65 | err_cachep: |
66 | kfree(pcache); |
67 | err_alloc: |
68 | mutex_unlock(&pid_caches_mutex); |
69 | return NULL; |
70 | } |
71 | |
72 | static struct pid_namespace *create_pid_namespace(struct pid_namespace *parent_pid_ns) |
73 | { |
74 | struct pid_namespace *ns; |
75 | unsigned int level = parent_pid_ns->level + 1; |
76 | int i, err = -ENOMEM; |
77 | |
78 | ns = kmem_cache_zalloc(pid_ns_cachep, GFP_KERNEL); |
79 | if (ns == NULL) |
80 | goto out; |
81 | |
82 | ns->pidmap[0].page = kzalloc(PAGE_SIZE, GFP_KERNEL); |
83 | if (!ns->pidmap[0].page) |
84 | goto out_free; |
85 | |
86 | ns->pid_cachep = create_pid_cachep(level + 1); |
87 | if (ns->pid_cachep == NULL) |
88 | goto out_free_map; |
89 | |
90 | kref_init(&ns->kref); |
91 | ns->level = level; |
92 | ns->parent = get_pid_ns(parent_pid_ns); |
93 | |
94 | set_bit(0, ns->pidmap[0].page); |
95 | atomic_set(&ns->pidmap[0].nr_free, BITS_PER_PAGE - 1); |
96 | |
97 | for (i = 1; i < PIDMAP_ENTRIES; i++) |
98 | atomic_set(&ns->pidmap[i].nr_free, BITS_PER_PAGE); |
99 | |
100 | err = pid_ns_prepare_proc(ns); |
101 | if (err) |
102 | goto out_put_parent_pid_ns; |
103 | |
104 | return ns; |
105 | |
106 | out_put_parent_pid_ns: |
107 | put_pid_ns(parent_pid_ns); |
108 | out_free_map: |
109 | kfree(ns->pidmap[0].page); |
110 | out_free: |
111 | kmem_cache_free(pid_ns_cachep, ns); |
112 | out: |
113 | return ERR_PTR(err); |
114 | } |
115 | |
116 | static void destroy_pid_namespace(struct pid_namespace *ns) |
117 | { |
118 | int i; |
119 | |
120 | for (i = 0; i < PIDMAP_ENTRIES; i++) |
121 | kfree(ns->pidmap[i].page); |
122 | kmem_cache_free(pid_ns_cachep, ns); |
123 | } |
124 | |
125 | struct pid_namespace *copy_pid_ns(unsigned long flags, struct pid_namespace *old_ns) |
126 | { |
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); |
132 | } |
133 | |
134 | void free_pid_ns(struct kref *kref) |
135 | { |
136 | struct pid_namespace *ns, *parent; |
137 | |
138 | ns = container_of(kref, struct pid_namespace, kref); |
139 | |
140 | parent = ns->parent; |
141 | destroy_pid_namespace(ns); |
142 | |
143 | if (parent != NULL) |
144 | put_pid_ns(parent); |
145 | } |
146 | |
147 | void zap_pid_ns_processes(struct pid_namespace *pid_ns) |
148 | { |
149 | int nr; |
150 | int rc; |
151 | struct task_struct *task; |
152 | |
153 | /* |
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 |
156 | * to exit. |
157 | * |
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. |
164 | * |
165 | */ |
166 | read_lock(&tasklist_lock); |
167 | nr = next_pidmap(pid_ns, 1); |
168 | while (nr > 0) { |
169 | rcu_read_lock(); |
170 | |
171 | /* |
172 | * Any nested-container's init processes won't ignore the |
173 | * SEND_SIG_NOINFO signal, see send_signal()->si_fromuser(). |
174 | */ |
175 | task = pid_task(find_vpid(nr), PIDTYPE_PID); |
176 | if (task) |
177 | send_sig_info(SIGKILL, SEND_SIG_NOINFO, task); |
178 | |
179 | rcu_read_unlock(); |
180 | |
181 | nr = next_pidmap(pid_ns, nr); |
182 | } |
183 | read_unlock(&tasklist_lock); |
184 | |
185 | do { |
186 | clear_thread_flag(TIF_SIGPENDING); |
187 | rc = sys_wait4(-1, NULL, __WALL, NULL); |
188 | } while (rc != -ECHILD); |
189 | |
190 | acct_exit_ns(pid_ns); |
191 | return; |
192 | } |
193 | |
194 | static __init int pid_namespaces_init(void) |
195 | { |
196 | pid_ns_cachep = KMEM_CACHE(pid_namespace, SLAB_PANIC); |
197 | return 0; |
198 | } |
199 | |
200 | __initcall(pid_namespaces_init); |
201 |
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