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 = &init_pid_ns,
39 #ifdef CONFIG_NET
40 .net_ns = &init_net,
41 #endif
42 };
43
create_nsproxy(void)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 */
create_new_namespaces(unsigned long flags,struct task_struct * tsk,struct user_namespace * user_ns,struct fs_struct * new_fs)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 = copy_pid_ns(flags, user_ns, tsk->nsproxy->pid_ns);
89 if (IS_ERR(new_nsp->pid_ns)) {
90 err = PTR_ERR(new_nsp->pid_ns);
91 goto out_pid;
92 }
93
94 new_nsp->net_ns = copy_net_ns(flags, user_ns, tsk->nsproxy->net_ns);
95 if (IS_ERR(new_nsp->net_ns)) {
96 err = PTR_ERR(new_nsp->net_ns);
97 goto out_net;
98 }
99
100 return new_nsp;
101
102 out_net:
103 if (new_nsp->pid_ns)
104 put_pid_ns(new_nsp->pid_ns);
105 out_pid:
106 if (new_nsp->ipc_ns)
107 put_ipc_ns(new_nsp->ipc_ns);
108 out_ipc:
109 if (new_nsp->uts_ns)
110 put_uts_ns(new_nsp->uts_ns);
111 out_uts:
112 if (new_nsp->mnt_ns)
113 put_mnt_ns(new_nsp->mnt_ns);
114 out_ns:
115 kmem_cache_free(nsproxy_cachep, new_nsp);
116 return ERR_PTR(err);
117 }
118
119 /*
120 * called from clone. This now handles copy for nsproxy and all
121 * namespaces therein.
122 */
copy_namespaces(unsigned long flags,struct task_struct * tsk)123 int copy_namespaces(unsigned long flags, struct task_struct *tsk)
124 {
125 struct nsproxy *old_ns = tsk->nsproxy;
126 struct user_namespace *user_ns = task_cred_xxx(tsk, user_ns);
127 struct nsproxy *new_ns;
128 int err = 0;
129
130 if (!old_ns)
131 return 0;
132
133 get_nsproxy(old_ns);
134
135 if (!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
136 CLONE_NEWPID | CLONE_NEWNET)))
137 return 0;
138
139 if (!ns_capable(user_ns, CAP_SYS_ADMIN)) {
140 err = -EPERM;
141 goto out;
142 }
143
144 /*
145 * CLONE_NEWIPC must detach from the undolist: after switching
146 * to a new ipc namespace, the semaphore arrays from the old
147 * namespace are unreachable. In clone parlance, CLONE_SYSVSEM
148 * means share undolist with parent, so we must forbid using
149 * it along with CLONE_NEWIPC.
150 */
151 if ((flags & CLONE_NEWIPC) && (flags & CLONE_SYSVSEM)) {
152 err = -EINVAL;
153 goto out;
154 }
155
156 new_ns = create_new_namespaces(flags, tsk, user_ns, tsk->fs);
157 if (IS_ERR(new_ns)) {
158 err = PTR_ERR(new_ns);
159 goto out;
160 }
161
162 tsk->nsproxy = new_ns;
163
164 out:
165 put_nsproxy(old_ns);
166 return err;
167 }
168
free_nsproxy(struct nsproxy * ns)169 void free_nsproxy(struct nsproxy *ns)
170 {
171 if (ns->mnt_ns)
172 put_mnt_ns(ns->mnt_ns);
173 if (ns->uts_ns)
174 put_uts_ns(ns->uts_ns);
175 if (ns->ipc_ns)
176 put_ipc_ns(ns->ipc_ns);
177 if (ns->pid_ns)
178 put_pid_ns(ns->pid_ns);
179 put_net(ns->net_ns);
180 kmem_cache_free(nsproxy_cachep, ns);
181 }
182
183 /*
184 * Called from unshare. Unshare all the namespaces part of nsproxy.
185 * On success, returns the new nsproxy.
186 */
unshare_nsproxy_namespaces(unsigned long unshare_flags,struct nsproxy ** new_nsp,struct cred * new_cred,struct fs_struct * new_fs)187 int unshare_nsproxy_namespaces(unsigned long unshare_flags,
188 struct nsproxy **new_nsp, struct cred *new_cred, struct fs_struct *new_fs)
189 {
190 struct user_namespace *user_ns;
191 int err = 0;
192
193 if (!(unshare_flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
194 CLONE_NEWNET | CLONE_NEWPID)))
195 return 0;
196
197 user_ns = new_cred ? new_cred->user_ns : current_user_ns();
198 if (!ns_capable(user_ns, CAP_SYS_ADMIN))
199 return -EPERM;
200
201 *new_nsp = create_new_namespaces(unshare_flags, current, user_ns,
202 new_fs ? new_fs : current->fs);
203 if (IS_ERR(*new_nsp)) {
204 err = PTR_ERR(*new_nsp);
205 goto out;
206 }
207
208 out:
209 return err;
210 }
211
switch_task_namespaces(struct task_struct * p,struct nsproxy * new)212 void switch_task_namespaces(struct task_struct *p, struct nsproxy *new)
213 {
214 struct nsproxy *ns;
215
216 might_sleep();
217
218 ns = p->nsproxy;
219
220 rcu_assign_pointer(p->nsproxy, new);
221
222 if (ns && atomic_dec_and_test(&ns->count)) {
223 /*
224 * wait for others to get what they want from this nsproxy.
225 *
226 * cannot release this nsproxy via the call_rcu() since
227 * put_mnt_ns() will want to sleep
228 */
229 synchronize_rcu();
230 free_nsproxy(ns);
231 }
232 }
233
exit_task_namespaces(struct task_struct * p)234 void exit_task_namespaces(struct task_struct *p)
235 {
236 switch_task_namespaces(p, NULL);
237 }
238
SYSCALL_DEFINE2(setns,int,fd,int,nstype)239 SYSCALL_DEFINE2(setns, int, fd, int, nstype)
240 {
241 const struct proc_ns_operations *ops;
242 struct task_struct *tsk = current;
243 struct nsproxy *new_nsproxy;
244 struct proc_ns *ei;
245 struct file *file;
246 int err;
247
248 file = proc_ns_fget(fd);
249 if (IS_ERR(file))
250 return PTR_ERR(file);
251
252 err = -EINVAL;
253 ei = get_proc_ns(file_inode(file));
254 ops = ei->ns_ops;
255 if (nstype && (ops->type != nstype))
256 goto out;
257
258 new_nsproxy = create_new_namespaces(0, tsk, current_user_ns(), tsk->fs);
259 if (IS_ERR(new_nsproxy)) {
260 err = PTR_ERR(new_nsproxy);
261 goto out;
262 }
263
264 err = ops->install(new_nsproxy, ei->ns);
265 if (err) {
266 free_nsproxy(new_nsproxy);
267 goto out;
268 }
269 switch_task_namespaces(tsk, new_nsproxy);
270 out:
271 fput(file);
272 return err;
273 }
274
nsproxy_cache_init(void)275 int __init nsproxy_cache_init(void)
276 {
277 nsproxy_cachep = KMEM_CACHE(nsproxy, SLAB_PANIC);
278 return 0;
279 }
280