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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> | |
13 | #include <linux/syscalls.h> | |
14 | #include <linux/err.h> | |
0b6b030f | 15 | #include <linux/acct.h> |
5a0e3ad6 | 16 | #include <linux/slab.h> |
74bd59bb PE |
17 | |
18 | #define BITS_PER_PAGE (PAGE_SIZE*8) | |
19 | ||
20 | struct pid_cache { | |
21 | int nr_ids; | |
22 | char name[16]; | |
23 | struct kmem_cache *cachep; | |
24 | struct list_head list; | |
25 | }; | |
26 | ||
27 | static LIST_HEAD(pid_caches_lh); | |
28 | static DEFINE_MUTEX(pid_caches_mutex); | |
29 | static struct kmem_cache *pid_ns_cachep; | |
30 | ||
31 | /* | |
32 | * creates the kmem cache to allocate pids from. | |
33 | * @nr_ids: the number of numerical ids this pid will have to carry | |
34 | */ | |
35 | ||
36 | static struct kmem_cache *create_pid_cachep(int nr_ids) | |
37 | { | |
38 | struct pid_cache *pcache; | |
39 | struct kmem_cache *cachep; | |
40 | ||
41 | mutex_lock(&pid_caches_mutex); | |
42 | list_for_each_entry(pcache, &pid_caches_lh, list) | |
43 | if (pcache->nr_ids == nr_ids) | |
44 | goto out; | |
45 | ||
46 | pcache = kmalloc(sizeof(struct pid_cache), GFP_KERNEL); | |
47 | if (pcache == NULL) | |
48 | goto err_alloc; | |
49 | ||
50 | snprintf(pcache->name, sizeof(pcache->name), "pid_%d", nr_ids); | |
51 | cachep = kmem_cache_create(pcache->name, | |
52 | sizeof(struct pid) + (nr_ids - 1) * sizeof(struct upid), | |
53 | 0, SLAB_HWCACHE_ALIGN, NULL); | |
54 | if (cachep == NULL) | |
55 | goto err_cachep; | |
56 | ||
57 | pcache->nr_ids = nr_ids; | |
58 | pcache->cachep = cachep; | |
59 | list_add(&pcache->list, &pid_caches_lh); | |
60 | out: | |
61 | mutex_unlock(&pid_caches_mutex); | |
62 | return pcache->cachep; | |
63 | ||
64 | err_cachep: | |
65 | kfree(pcache); | |
66 | err_alloc: | |
67 | mutex_unlock(&pid_caches_mutex); | |
68 | return NULL; | |
69 | } | |
70 | ||
ed469a63 | 71 | static struct pid_namespace *create_pid_namespace(struct pid_namespace *parent_pid_ns) |
74bd59bb PE |
72 | { |
73 | struct pid_namespace *ns; | |
ed469a63 | 74 | unsigned int level = parent_pid_ns->level + 1; |
74bd59bb PE |
75 | int i; |
76 | ||
84406c15 | 77 | ns = kmem_cache_zalloc(pid_ns_cachep, GFP_KERNEL); |
74bd59bb PE |
78 | if (ns == NULL) |
79 | goto out; | |
80 | ||
81 | ns->pidmap[0].page = kzalloc(PAGE_SIZE, GFP_KERNEL); | |
82 | if (!ns->pidmap[0].page) | |
83 | goto out_free; | |
84 | ||
85 | ns->pid_cachep = create_pid_cachep(level + 1); | |
86 | if (ns->pid_cachep == NULL) | |
87 | goto out_free_map; | |
88 | ||
89 | kref_init(&ns->kref); | |
74bd59bb | 90 | ns->level = level; |
ed469a63 | 91 | ns->parent = get_pid_ns(parent_pid_ns); |
74bd59bb PE |
92 | |
93 | set_bit(0, ns->pidmap[0].page); | |
94 | atomic_set(&ns->pidmap[0].nr_free, BITS_PER_PAGE - 1); | |
95 | ||
84406c15 | 96 | for (i = 1; i < PIDMAP_ENTRIES; i++) |
74bd59bb | 97 | atomic_set(&ns->pidmap[i].nr_free, BITS_PER_PAGE); |
74bd59bb PE |
98 | |
99 | return ns; | |
100 | ||
101 | out_free_map: | |
102 | kfree(ns->pidmap[0].page); | |
103 | out_free: | |
104 | kmem_cache_free(pid_ns_cachep, ns); | |
105 | out: | |
106 | return ERR_PTR(-ENOMEM); | |
107 | } | |
108 | ||
109 | static void destroy_pid_namespace(struct pid_namespace *ns) | |
110 | { | |
111 | int i; | |
112 | ||
113 | for (i = 0; i < PIDMAP_ENTRIES; i++) | |
114 | kfree(ns->pidmap[i].page); | |
115 | kmem_cache_free(pid_ns_cachep, ns); | |
116 | } | |
117 | ||
118 | struct pid_namespace *copy_pid_ns(unsigned long flags, struct pid_namespace *old_ns) | |
119 | { | |
74bd59bb | 120 | if (!(flags & CLONE_NEWPID)) |
dca4a979 | 121 | return get_pid_ns(old_ns); |
e5a47386 | 122 | if (flags & (CLONE_THREAD|CLONE_PARENT)) |
dca4a979 AD |
123 | return ERR_PTR(-EINVAL); |
124 | return create_pid_namespace(old_ns); | |
74bd59bb PE |
125 | } |
126 | ||
127 | void free_pid_ns(struct kref *kref) | |
128 | { | |
129 | struct pid_namespace *ns, *parent; | |
130 | ||
131 | ns = container_of(kref, struct pid_namespace, kref); | |
132 | ||
133 | parent = ns->parent; | |
134 | destroy_pid_namespace(ns); | |
135 | ||
136 | if (parent != NULL) | |
137 | put_pid_ns(parent); | |
138 | } | |
139 | ||
140 | void zap_pid_ns_processes(struct pid_namespace *pid_ns) | |
141 | { | |
142 | int nr; | |
143 | int rc; | |
e4da026f | 144 | struct task_struct *task; |
74bd59bb PE |
145 | |
146 | /* | |
147 | * The last thread in the cgroup-init thread group is terminating. | |
148 | * Find remaining pid_ts in the namespace, signal and wait for them | |
149 | * to exit. | |
150 | * | |
151 | * Note: This signals each threads in the namespace - even those that | |
152 | * belong to the same thread group, To avoid this, we would have | |
153 | * to walk the entire tasklist looking a processes in this | |
154 | * namespace, but that could be unnecessarily expensive if the | |
155 | * pid namespace has just a few processes. Or we need to | |
156 | * maintain a tasklist for each pid namespace. | |
157 | * | |
158 | */ | |
159 | read_lock(&tasklist_lock); | |
160 | nr = next_pidmap(pid_ns, 1); | |
161 | while (nr > 0) { | |
e4da026f SB |
162 | rcu_read_lock(); |
163 | ||
164 | /* | |
13aa9a6b ON |
165 | * Any nested-container's init processes won't ignore the |
166 | * SEND_SIG_NOINFO signal, see send_signal()->si_fromuser(). | |
e4da026f SB |
167 | */ |
168 | task = pid_task(find_vpid(nr), PIDTYPE_PID); | |
169 | if (task) | |
13aa9a6b | 170 | send_sig_info(SIGKILL, SEND_SIG_NOINFO, task); |
e4da026f SB |
171 | |
172 | rcu_read_unlock(); | |
173 | ||
74bd59bb PE |
174 | 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 | ||
0b6b030f | 183 | acct_exit_ns(pid_ns); |
74bd59bb PE |
184 | return; |
185 | } | |
186 | ||
187 | static __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); |