Root/kernel/nsproxy.c

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_fs.h>
26#include <linux/file.h>
27#include <linux/syscalls.h>
28
29static struct kmem_cache *nsproxy_cachep;
30
31struct 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
44static 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 */
59static struct nsproxy *create_new_namespaces(unsigned long flags,
60            struct task_struct *tsk, struct fs_struct *new_fs)
61{
62    struct nsproxy *new_nsp;
63    int err;
64
65    new_nsp = create_nsproxy();
66    if (!new_nsp)
67        return ERR_PTR(-ENOMEM);
68
69    new_nsp->mnt_ns = copy_mnt_ns(flags, tsk->nsproxy->mnt_ns, new_fs);
70    if (IS_ERR(new_nsp->mnt_ns)) {
71        err = PTR_ERR(new_nsp->mnt_ns);
72        goto out_ns;
73    }
74
75    new_nsp->uts_ns = copy_utsname(flags, tsk);
76    if (IS_ERR(new_nsp->uts_ns)) {
77        err = PTR_ERR(new_nsp->uts_ns);
78        goto out_uts;
79    }
80
81    new_nsp->ipc_ns = copy_ipcs(flags, tsk);
82    if (IS_ERR(new_nsp->ipc_ns)) {
83        err = PTR_ERR(new_nsp->ipc_ns);
84        goto out_ipc;
85    }
86
87    new_nsp->pid_ns = copy_pid_ns(flags, task_active_pid_ns(tsk));
88    if (IS_ERR(new_nsp->pid_ns)) {
89        err = PTR_ERR(new_nsp->pid_ns);
90        goto out_pid;
91    }
92
93    new_nsp->net_ns = copy_net_ns(flags, tsk->nsproxy->net_ns);
94    if (IS_ERR(new_nsp->net_ns)) {
95        err = PTR_ERR(new_nsp->net_ns);
96        goto out_net;
97    }
98
99    return new_nsp;
100
101out_net:
102    if (new_nsp->pid_ns)
103        put_pid_ns(new_nsp->pid_ns);
104out_pid:
105    if (new_nsp->ipc_ns)
106        put_ipc_ns(new_nsp->ipc_ns);
107out_ipc:
108    if (new_nsp->uts_ns)
109        put_uts_ns(new_nsp->uts_ns);
110out_uts:
111    if (new_nsp->mnt_ns)
112        put_mnt_ns(new_nsp->mnt_ns);
113out_ns:
114    kmem_cache_free(nsproxy_cachep, new_nsp);
115    return ERR_PTR(err);
116}
117
118/*
119 * called from clone. This now handles copy for nsproxy and all
120 * namespaces therein.
121 */
122int copy_namespaces(unsigned long flags, struct task_struct *tsk)
123{
124    struct nsproxy *old_ns = tsk->nsproxy;
125    struct nsproxy *new_ns;
126    int err = 0;
127
128    if (!old_ns)
129        return 0;
130
131    get_nsproxy(old_ns);
132
133    if (!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
134                CLONE_NEWPID | CLONE_NEWNET)))
135        return 0;
136
137    if (!capable(CAP_SYS_ADMIN)) {
138        err = -EPERM;
139        goto out;
140    }
141
142    /*
143     * CLONE_NEWIPC must detach from the undolist: after switching
144     * to a new ipc namespace, the semaphore arrays from the old
145     * namespace are unreachable. In clone parlance, CLONE_SYSVSEM
146     * means share undolist with parent, so we must forbid using
147     * it along with CLONE_NEWIPC.
148     */
149    if ((flags & CLONE_NEWIPC) && (flags & CLONE_SYSVSEM)) {
150        err = -EINVAL;
151        goto out;
152    }
153
154    new_ns = create_new_namespaces(flags, tsk, tsk->fs);
155    if (IS_ERR(new_ns)) {
156        err = PTR_ERR(new_ns);
157        goto out;
158    }
159
160    tsk->nsproxy = new_ns;
161
162out:
163    put_nsproxy(old_ns);
164    return err;
165}
166
167void free_nsproxy(struct nsproxy *ns)
168{
169    if (ns->mnt_ns)
170        put_mnt_ns(ns->mnt_ns);
171    if (ns->uts_ns)
172        put_uts_ns(ns->uts_ns);
173    if (ns->ipc_ns)
174        put_ipc_ns(ns->ipc_ns);
175    if (ns->pid_ns)
176        put_pid_ns(ns->pid_ns);
177    put_net(ns->net_ns);
178    kmem_cache_free(nsproxy_cachep, ns);
179}
180
181/*
182 * Called from unshare. Unshare all the namespaces part of nsproxy.
183 * On success, returns the new nsproxy.
184 */
185int unshare_nsproxy_namespaces(unsigned long unshare_flags,
186        struct nsproxy **new_nsp, struct fs_struct *new_fs)
187{
188    int err = 0;
189
190    if (!(unshare_flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
191                   CLONE_NEWNET)))
192        return 0;
193
194    if (!capable(CAP_SYS_ADMIN))
195        return -EPERM;
196
197    *new_nsp = create_new_namespaces(unshare_flags, current,
198                new_fs ? new_fs : current->fs);
199    if (IS_ERR(*new_nsp)) {
200        err = PTR_ERR(*new_nsp);
201        goto out;
202    }
203
204out:
205    return err;
206}
207
208void switch_task_namespaces(struct task_struct *p, struct nsproxy *new)
209{
210    struct nsproxy *ns;
211
212    might_sleep();
213
214    ns = p->nsproxy;
215
216    rcu_assign_pointer(p->nsproxy, new);
217
218    if (ns && atomic_dec_and_test(&ns->count)) {
219        /*
220         * wait for others to get what they want from this nsproxy.
221         *
222         * cannot release this nsproxy via the call_rcu() since
223         * put_mnt_ns() will want to sleep
224         */
225        synchronize_rcu();
226        free_nsproxy(ns);
227    }
228}
229
230void exit_task_namespaces(struct task_struct *p)
231{
232    switch_task_namespaces(p, NULL);
233}
234
235SYSCALL_DEFINE2(setns, int, fd, int, nstype)
236{
237    const struct proc_ns_operations *ops;
238    struct task_struct *tsk = current;
239    struct nsproxy *new_nsproxy;
240    struct proc_inode *ei;
241    struct file *file;
242    int err;
243
244    if (!capable(CAP_SYS_ADMIN))
245        return -EPERM;
246
247    file = proc_ns_fget(fd);
248    if (IS_ERR(file))
249        return PTR_ERR(file);
250
251    err = -EINVAL;
252    ei = PROC_I(file->f_dentry->d_inode);
253    ops = ei->ns_ops;
254    if (nstype && (ops->type != nstype))
255        goto out;
256
257    new_nsproxy = create_new_namespaces(0, tsk, tsk->fs);
258    if (IS_ERR(new_nsproxy)) {
259        err = PTR_ERR(new_nsproxy);
260        goto out;
261    }
262
263    err = ops->install(new_nsproxy, ei->ns);
264    if (err) {
265        free_nsproxy(new_nsproxy);
266        goto out;
267    }
268    switch_task_namespaces(tsk, new_nsproxy);
269out:
270    fput(file);
271    return err;
272}
273
274int __init nsproxy_cache_init(void)
275{
276    nsproxy_cachep = KMEM_CACHE(nsproxy, SLAB_PANIC);
277    return 0;
278}
279

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