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_ns.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_for_children = &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 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
103out_net:
104    if (new_nsp->pid_ns_for_children)
105        put_pid_ns(new_nsp->pid_ns_for_children);
106out_pid:
107    if (new_nsp->ipc_ns)
108        put_ipc_ns(new_nsp->ipc_ns);
109out_ipc:
110    if (new_nsp->uts_ns)
111        put_uts_ns(new_nsp->uts_ns);
112out_uts:
113    if (new_nsp->mnt_ns)
114        put_mnt_ns(new_nsp->mnt_ns);
115out_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 */
124int 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
158void 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 */
176int 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
197out:
198    return err;
199}
200
201void switch_task_namespaces(struct task_struct *p, struct nsproxy *new)
202{
203    struct nsproxy *ns;
204
205    might_sleep();
206
207    ns = p->nsproxy;
208
209    rcu_assign_pointer(p->nsproxy, new);
210
211    if (ns && atomic_dec_and_test(&ns->count)) {
212        /*
213         * wait for others to get what they want from this nsproxy.
214         *
215         * cannot release this nsproxy via the call_rcu() since
216         * put_mnt_ns() will want to sleep
217         */
218        synchronize_rcu();
219        free_nsproxy(ns);
220    }
221}
222
223void exit_task_namespaces(struct task_struct *p)
224{
225    switch_task_namespaces(p, NULL);
226}
227
228SYSCALL_DEFINE2(setns, int, fd, int, nstype)
229{
230    const struct proc_ns_operations *ops;
231    struct task_struct *tsk = current;
232    struct nsproxy *new_nsproxy;
233    struct proc_ns *ei;
234    struct file *file;
235    int err;
236
237    file = proc_ns_fget(fd);
238    if (IS_ERR(file))
239        return PTR_ERR(file);
240
241    err = -EINVAL;
242    ei = get_proc_ns(file_inode(file));
243    ops = ei->ns_ops;
244    if (nstype && (ops->type != nstype))
245        goto out;
246
247    new_nsproxy = create_new_namespaces(0, tsk, current_user_ns(), tsk->fs);
248    if (IS_ERR(new_nsproxy)) {
249        err = PTR_ERR(new_nsproxy);
250        goto out;
251    }
252
253    err = ops->install(new_nsproxy, ei->ns);
254    if (err) {
255        free_nsproxy(new_nsproxy);
256        goto out;
257    }
258    switch_task_namespaces(tsk, new_nsproxy);
259out:
260    fput(file);
261    return err;
262}
263
264int __init nsproxy_cache_init(void)
265{
266    nsproxy_cachep = KMEM_CACHE(nsproxy, SLAB_PANIC);
267    return 0;
268}
269

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