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
26static struct kmem_cache *nsproxy_cachep;
27
28struct 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
41static 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 */
56static 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
98out_net:
99	if (new_nsp->pid_ns)
100		put_pid_ns(new_nsp->pid_ns);
101out_pid:
102	if (new_nsp->ipc_ns)
103		put_ipc_ns(new_nsp->ipc_ns);
104out_ipc:
105	if (new_nsp->uts_ns)
106		put_uts_ns(new_nsp->uts_ns);
107out_uts:
108	if (new_nsp->mnt_ns)
109		put_mnt_ns(new_nsp->mnt_ns);
110out_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 */
119int 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
159out:
160	put_nsproxy(old_ns);
161	return err;
162}
163
164void 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 */
182int 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
205out:
206	return err;
207}
208
209void 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
231void exit_task_namespaces(struct task_struct *p)
232{
233	switch_task_namespaces(p, NULL);
234}
235
236static int __init nsproxy_cache_init(void)
237{
238	nsproxy_cachep = KMEM_CACHE(nsproxy, SLAB_PANIC);
239	return 0;
240}
241
242module_init(nsproxy_cache_init);
243