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 
 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 
 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 = 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  */
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 
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  */
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 
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 
234 void exit_task_namespaces(struct task_struct *p)
235 {
236         switch_task_namespaces(p, NULL);
237 }
238 
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_inode *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 = PROC_I(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 
275 int __init nsproxy_cache_init(void)
276 {
277         nsproxy_cachep = KMEM_CACHE(nsproxy, SLAB_PANIC);
278         return 0;
279 }
280
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