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1 /*
2 * Copyright (C) 2006 IBM Corporation
3 *
4 * Author: Serge Hallyn <serue@us.ibm.com>
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License as
8 * published by the Free Software Foundation, version 2 of the
9 * License.
10 *
11 * Jun 2006 - namespaces support
12 * OpenVZ, SWsoft Inc.
13 * Pavel Emelianov <xemul@openvz.org>
14 */
15
16 #include <linux/slab.h>
17 #include <linux/module.h>
18 #include <linux/nsproxy.h>
19 #include <linux/init_task.h>
20 #include <linux/mnt_namespace.h>
21 #include <linux/utsname.h>
22 #include <linux/pid_namespace.h>
23 #include <net/net_namespace.h>
24 #include <linux/ipc_namespace.h>
25
26 static struct kmem_cache *nsproxy_cachep;
27
28 struct nsproxy init_nsproxy = {
29 .count = ATOMIC_INIT(1),
30 .uts_ns = &init_uts_ns,
31 #if defined(CONFIG_POSIX_MQUEUE) || defined(CONFIG_SYSVIPC)
32 .ipc_ns = &init_ipc_ns,
33 #endif
34 .mnt_ns = NULL,
35 .pid_ns = &init_pid_ns,
36 #ifdef CONFIG_NET
37 .net_ns = &init_net,
38 #endif
39 };
40
41 static inline struct nsproxy *create_nsproxy(void)
42 {
43 struct nsproxy *nsproxy;
44
45 nsproxy = kmem_cache_alloc(nsproxy_cachep, GFP_KERNEL);
46 if (nsproxy)
47 atomic_set(&nsproxy->count, 1);
48 return nsproxy;
49 }
50
51 /*
52 * Create new nsproxy and all of its the associated namespaces.
53 * Return the newly created nsproxy. Do not attach this to the task,
54 * leave it to the caller to do proper locking and attach it to task.
55 */
56 static struct nsproxy *create_new_namespaces(unsigned long flags,
57 struct task_struct *tsk, struct fs_struct *new_fs)
58 {
59 struct nsproxy *new_nsp;
60 int err;
61
62 new_nsp = create_nsproxy();
63 if (!new_nsp)
64 return ERR_PTR(-ENOMEM);
65
66 new_nsp->mnt_ns = copy_mnt_ns(flags, tsk->nsproxy->mnt_ns, new_fs);
67 if (IS_ERR(new_nsp->mnt_ns)) {
68 err = PTR_ERR(new_nsp->mnt_ns);
69 goto out_ns;
70 }
71
72 new_nsp->uts_ns = copy_utsname(flags, tsk->nsproxy->uts_ns);
73 if (IS_ERR(new_nsp->uts_ns)) {
74 err = PTR_ERR(new_nsp->uts_ns);
75 goto out_uts;
76 }
77
78 new_nsp->ipc_ns = copy_ipcs(flags, tsk->nsproxy->ipc_ns);
79 if (IS_ERR(new_nsp->ipc_ns)) {
80 err = PTR_ERR(new_nsp->ipc_ns);
81 goto out_ipc;
82 }
83
84 new_nsp->pid_ns = copy_pid_ns(flags, task_active_pid_ns(tsk));
85 if (IS_ERR(new_nsp->pid_ns)) {
86 err = PTR_ERR(new_nsp->pid_ns);
87 goto out_pid;
88 }
89
90 new_nsp->net_ns = copy_net_ns(flags, tsk->nsproxy->net_ns);
91 if (IS_ERR(new_nsp->net_ns)) {
92 err = PTR_ERR(new_nsp->net_ns);
93 goto out_net;
94 }
95
96 return new_nsp;
97
98 out_net:
99 if (new_nsp->pid_ns)
100 put_pid_ns(new_nsp->pid_ns);
101 out_pid:
102 if (new_nsp->ipc_ns)
103 put_ipc_ns(new_nsp->ipc_ns);
104 out_ipc:
105 if (new_nsp->uts_ns)
106 put_uts_ns(new_nsp->uts_ns);
107 out_uts:
108 if (new_nsp->mnt_ns)
109 put_mnt_ns(new_nsp->mnt_ns);
110 out_ns:
111 kmem_cache_free(nsproxy_cachep, new_nsp);
112 return ERR_PTR(err);
113 }
114
115 /*
116 * called from clone. This now handles copy for nsproxy and all
117 * namespaces therein.
118 */
119 int copy_namespaces(unsigned long flags, struct task_struct *tsk)
120 {
121 struct nsproxy *old_ns = tsk->nsproxy;
122 struct nsproxy *new_ns;
123 int err = 0;
124
125 if (!old_ns)
126 return 0;
127
128 get_nsproxy(old_ns);
129
130 if (!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
131 CLONE_NEWPID | CLONE_NEWNET)))
132 return 0;
133
134 if (!capable(CAP_SYS_ADMIN)) {
135 err = -EPERM;
136 goto out;
137 }
138
139 /*
140 * CLONE_NEWIPC must detach from the undolist: after switching
141 * to a new ipc namespace, the semaphore arrays from the old
142 * namespace are unreachable. In clone parlance, CLONE_SYSVSEM
143 * means share undolist with parent, so we must forbid using
144 * it along with CLONE_NEWIPC.
145 */
146 if ((flags & CLONE_NEWIPC) && (flags & CLONE_SYSVSEM)) {
147 err = -EINVAL;
148 goto out;
149 }
150
151 new_ns = create_new_namespaces(flags, tsk, tsk->fs);
152 if (IS_ERR(new_ns)) {
153 err = PTR_ERR(new_ns);
154 goto out;
155 }
156
157 tsk->nsproxy = new_ns;
158
159 out:
160 put_nsproxy(old_ns);
161 return err;
162 }
163
164 void free_nsproxy(struct nsproxy *ns)
165 {
166 if (ns->mnt_ns)
167 put_mnt_ns(ns->mnt_ns);
168 if (ns->uts_ns)
169 put_uts_ns(ns->uts_ns);
170 if (ns->ipc_ns)
171 put_ipc_ns(ns->ipc_ns);
172 if (ns->pid_ns)
173 put_pid_ns(ns->pid_ns);
174 put_net(ns->net_ns);
175 kmem_cache_free(nsproxy_cachep, ns);
176 }
177
178 /*
179 * Called from unshare. Unshare all the namespaces part of nsproxy.
180 * On success, returns the new nsproxy.
181 */
182 int unshare_nsproxy_namespaces(unsigned long unshare_flags,
183 struct nsproxy **new_nsp, struct fs_struct *new_fs)
184 {
185 int err = 0;
186
187 if (!(unshare_flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
188 CLONE_NEWNET)))
189 return 0;
190
191 if (!capable(CAP_SYS_ADMIN))
192 return -EPERM;
193
194 *new_nsp = create_new_namespaces(unshare_flags, current,
195 new_fs ? new_fs : current->fs);
196 if (IS_ERR(*new_nsp)) {
197 err = PTR_ERR(*new_nsp);
198 goto out;
199 }
200
201 err = ns_cgroup_clone(current, task_pid(current));
202 if (err)
203 put_nsproxy(*new_nsp);
204
205 out:
206 return err;
207 }
208
209 void switch_task_namespaces(struct task_struct *p, struct nsproxy *new)
210 {
211 struct nsproxy *ns;
212
213 might_sleep();
214
215 ns = p->nsproxy;
216
217 rcu_assign_pointer(p->nsproxy, new);
218
219 if (ns && atomic_dec_and_test(&ns->count)) {
220 /*
221 * wait for others to get what they want from this nsproxy.
222 *
223 * cannot release this nsproxy via the call_rcu() since
224 * put_mnt_ns() will want to sleep
225 */
226 synchronize_rcu();
227 free_nsproxy(ns);
228 }
229 }
230
231 void exit_task_namespaces(struct task_struct *p)
232 {
233 switch_task_namespaces(p, NULL);
234 }
235
236 static int __init nsproxy_cache_init(void)
237 {
238 nsproxy_cachep = KMEM_CACHE(nsproxy, SLAB_PANIC);
239 return 0;
240 }
241
242 module_init(nsproxy_cache_init);