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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/export.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 #include <linux/proc_ns.h>
26 #include <linux/file.h>
27 #include <linux/syscalls.h>
28
29 static struct kmem_cache *nsproxy_cachep;
30
31 struct nsproxy init_nsproxy = {
32 .count = ATOMIC_INIT(1),
33 .uts_ns = &init_uts_ns,
34 #if defined(CONFIG_POSIX_MQUEUE) || defined(CONFIG_SYSVIPC)
35 .ipc_ns = &init_ipc_ns,
36 #endif
37 .mnt_ns = NULL,
38 .pid_ns_for_children = &init_pid_ns,
39 #ifdef CONFIG_NET
40 .net_ns = &init_net,
41 #endif
42 };
43
44 static inline struct nsproxy *create_nsproxy(void)
45 {
46 struct nsproxy *nsproxy;
47
48 nsproxy = kmem_cache_alloc(nsproxy_cachep, GFP_KERNEL);
49 if (nsproxy)
50 atomic_set(&nsproxy->count, 1);
51 return nsproxy;
52 }
53
54 /*
55 * Create new nsproxy and all of its the associated namespaces.
56 * Return the newly created nsproxy. Do not attach this to the task,
57 * leave it to the caller to do proper locking and attach it to task.
58 */
59 static struct nsproxy *create_new_namespaces(unsigned long flags,
60 struct task_struct *tsk, struct user_namespace *user_ns,
61 struct fs_struct *new_fs)
62 {
63 struct nsproxy *new_nsp;
64 int err;
65
66 new_nsp = create_nsproxy();
67 if (!new_nsp)
68 return ERR_PTR(-ENOMEM);
69
70 new_nsp->mnt_ns = copy_mnt_ns(flags, tsk->nsproxy->mnt_ns, user_ns, new_fs);
71 if (IS_ERR(new_nsp->mnt_ns)) {
72 err = PTR_ERR(new_nsp->mnt_ns);
73 goto out_ns;
74 }
75
76 new_nsp->uts_ns = copy_utsname(flags, user_ns, tsk->nsproxy->uts_ns);
77 if (IS_ERR(new_nsp->uts_ns)) {
78 err = PTR_ERR(new_nsp->uts_ns);
79 goto out_uts;
80 }
81
82 new_nsp->ipc_ns = copy_ipcs(flags, user_ns, tsk->nsproxy->ipc_ns);
83 if (IS_ERR(new_nsp->ipc_ns)) {
84 err = PTR_ERR(new_nsp->ipc_ns);
85 goto out_ipc;
86 }
87
88 new_nsp->pid_ns_for_children =
89 copy_pid_ns(flags, user_ns, tsk->nsproxy->pid_ns_for_children);
90 if (IS_ERR(new_nsp->pid_ns_for_children)) {
91 err = PTR_ERR(new_nsp->pid_ns_for_children);
92 goto out_pid;
93 }
94
95 new_nsp->net_ns = copy_net_ns(flags, user_ns, tsk->nsproxy->net_ns);
96 if (IS_ERR(new_nsp->net_ns)) {
97 err = PTR_ERR(new_nsp->net_ns);
98 goto out_net;
99 }
100
101 return new_nsp;
102
103 out_net:
104 if (new_nsp->pid_ns_for_children)
105 put_pid_ns(new_nsp->pid_ns_for_children);
106 out_pid:
107 if (new_nsp->ipc_ns)
108 put_ipc_ns(new_nsp->ipc_ns);
109 out_ipc:
110 if (new_nsp->uts_ns)
111 put_uts_ns(new_nsp->uts_ns);
112 out_uts:
113 if (new_nsp->mnt_ns)
114 put_mnt_ns(new_nsp->mnt_ns);
115 out_ns:
116 kmem_cache_free(nsproxy_cachep, new_nsp);
117 return ERR_PTR(err);
118 }
119
120 /*
121 * called from clone. This now handles copy for nsproxy and all
122 * namespaces therein.
123 */
124 int copy_namespaces(unsigned long flags, struct task_struct *tsk)
125 {
126 struct nsproxy *old_ns = tsk->nsproxy;
127 struct user_namespace *user_ns = task_cred_xxx(tsk, user_ns);
128 struct nsproxy *new_ns;
129
130 if (likely(!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
131 CLONE_NEWPID | CLONE_NEWNET)))) {
132 get_nsproxy(old_ns);
133 return 0;
134 }
135
136 if (!ns_capable(user_ns, CAP_SYS_ADMIN))
137 return -EPERM;
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 | CLONE_SYSVSEM)) ==
147 (CLONE_NEWIPC | CLONE_SYSVSEM))
148 return -EINVAL;
149
150 new_ns = create_new_namespaces(flags, tsk, user_ns, tsk->fs);
151 if (IS_ERR(new_ns))
152 return PTR_ERR(new_ns);
153
154 tsk->nsproxy = new_ns;
155 return 0;
156 }
157
158 void free_nsproxy(struct nsproxy *ns)
159 {
160 if (ns->mnt_ns)
161 put_mnt_ns(ns->mnt_ns);
162 if (ns->uts_ns)
163 put_uts_ns(ns->uts_ns);
164 if (ns->ipc_ns)
165 put_ipc_ns(ns->ipc_ns);
166 if (ns->pid_ns_for_children)
167 put_pid_ns(ns->pid_ns_for_children);
168 put_net(ns->net_ns);
169 kmem_cache_free(nsproxy_cachep, ns);
170 }
171
172 /*
173 * Called from unshare. Unshare all the namespaces part of nsproxy.
174 * On success, returns the new nsproxy.
175 */
176 int unshare_nsproxy_namespaces(unsigned long unshare_flags,
177 struct nsproxy **new_nsp, struct cred *new_cred, struct fs_struct *new_fs)
178 {
179 struct user_namespace *user_ns;
180 int err = 0;
181
182 if (!(unshare_flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
183 CLONE_NEWNET | CLONE_NEWPID)))
184 return 0;
185
186 user_ns = new_cred ? new_cred->user_ns : current_user_ns();
187 if (!ns_capable(user_ns, CAP_SYS_ADMIN))
188 return -EPERM;
189
190 *new_nsp = create_new_namespaces(unshare_flags, current, user_ns,
191 new_fs ? new_fs : current->fs);
192 if (IS_ERR(*new_nsp)) {
193 err = PTR_ERR(*new_nsp);
194 goto out;
195 }
196
197 out:
198 return err;
199 }
200
201 void switch_task_namespaces(struct task_struct *p, struct nsproxy *new)
202 {
203 struct nsproxy *ns;
204
205 might_sleep();
206
207 task_lock(p);
208 ns = p->nsproxy;
209 p->nsproxy = new;
210 task_unlock(p);
211
212 if (ns && atomic_dec_and_test(&ns->count))
213 free_nsproxy(ns);
214 }
215
216 void exit_task_namespaces(struct task_struct *p)
217 {
218 switch_task_namespaces(p, NULL);
219 }
220
221 SYSCALL_DEFINE2(setns, int, fd, int, nstype)
222 {
223 struct task_struct *tsk = current;
224 struct nsproxy *new_nsproxy;
225 struct file *file;
226 struct ns_common *ns;
227 int err;
228
229 file = proc_ns_fget(fd);
230 if (IS_ERR(file))
231 return PTR_ERR(file);
232
233 err = -EINVAL;
234 ns = get_proc_ns(file_inode(file));
235 if (nstype && (ns->ops->type != nstype))
236 goto out;
237
238 new_nsproxy = create_new_namespaces(0, tsk, current_user_ns(), tsk->fs);
239 if (IS_ERR(new_nsproxy)) {
240 err = PTR_ERR(new_nsproxy);
241 goto out;
242 }
243
244 err = ns->ops->install(new_nsproxy, ns);
245 if (err) {
246 free_nsproxy(new_nsproxy);
247 goto out;
248 }
249 switch_task_namespaces(tsk, new_nsproxy);
250 out:
251 fput(file);
252 return err;
253 }
254
255 int __init nsproxy_cache_init(void)
256 {
257 nsproxy_cachep = KMEM_CACHE(nsproxy, SLAB_PANIC);
258 return 0;
259 }