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Linux/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 
 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_for_children    = &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_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 
103 out_net:
104         if (new_nsp->pid_ns_for_children)
105                 put_pid_ns(new_nsp->pid_ns_for_children);
106 out_pid:
107         if (new_nsp->ipc_ns)
108                 put_ipc_ns(new_nsp->ipc_ns);
109 out_ipc:
110         if (new_nsp->uts_ns)
111                 put_uts_ns(new_nsp->uts_ns);
112 out_uts:
113         if (new_nsp->mnt_ns)
114                 put_mnt_ns(new_nsp->mnt_ns);
115 out_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  */
124 int 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 
158 void 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  */
176 int 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 
197 out:
198         return err;
199 }
200 
201 void 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 
223 void exit_task_namespaces(struct task_struct *p)
224 {
225         switch_task_namespaces(p, NULL);
226 }
227 
228 SYSCALL_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);
259 out:
260         fput(file);
261         return err;
262 }
263 
264 int __init nsproxy_cache_init(void)
265 {
266         nsproxy_cachep = KMEM_CACHE(nsproxy, SLAB_PANIC);
267         return 0;
268 }
269 

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