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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 #include <linux/cgroup.h>
 29 
 30 static struct kmem_cache *nsproxy_cachep;
 31 
 32 struct nsproxy init_nsproxy = {
 33         .count                  = ATOMIC_INIT(1),
 34         .uts_ns                 = &init_uts_ns,
 35 #if defined(CONFIG_POSIX_MQUEUE) || defined(CONFIG_SYSVIPC)
 36         .ipc_ns                 = &init_ipc_ns,
 37 #endif
 38         .mnt_ns                 = NULL,
 39         .pid_ns_for_children    = &init_pid_ns,
 40 #ifdef CONFIG_NET
 41         .net_ns                 = &init_net,
 42 #endif
 43 #ifdef CONFIG_CGROUPS
 44         .cgroup_ns              = &init_cgroup_ns,
 45 #endif
 46 };
 47 
 48 static inline struct nsproxy *create_nsproxy(void)
 49 {
 50         struct nsproxy *nsproxy;
 51 
 52         nsproxy = kmem_cache_alloc(nsproxy_cachep, GFP_KERNEL);
 53         if (nsproxy)
 54                 atomic_set(&nsproxy->count, 1);
 55         return nsproxy;
 56 }
 57 
 58 /*
 59  * Create new nsproxy and all of its the associated namespaces.
 60  * Return the newly created nsproxy.  Do not attach this to the task,
 61  * leave it to the caller to do proper locking and attach it to task.
 62  */
 63 static struct nsproxy *create_new_namespaces(unsigned long flags,
 64         struct task_struct *tsk, struct user_namespace *user_ns,
 65         struct fs_struct *new_fs)
 66 {
 67         struct nsproxy *new_nsp;
 68         int err;
 69 
 70         new_nsp = create_nsproxy();
 71         if (!new_nsp)
 72                 return ERR_PTR(-ENOMEM);
 73 
 74         new_nsp->mnt_ns = copy_mnt_ns(flags, tsk->nsproxy->mnt_ns, user_ns, new_fs);
 75         if (IS_ERR(new_nsp->mnt_ns)) {
 76                 err = PTR_ERR(new_nsp->mnt_ns);
 77                 goto out_ns;
 78         }
 79 
 80         new_nsp->uts_ns = copy_utsname(flags, user_ns, tsk->nsproxy->uts_ns);
 81         if (IS_ERR(new_nsp->uts_ns)) {
 82                 err = PTR_ERR(new_nsp->uts_ns);
 83                 goto out_uts;
 84         }
 85 
 86         new_nsp->ipc_ns = copy_ipcs(flags, user_ns, tsk->nsproxy->ipc_ns);
 87         if (IS_ERR(new_nsp->ipc_ns)) {
 88                 err = PTR_ERR(new_nsp->ipc_ns);
 89                 goto out_ipc;
 90         }
 91 
 92         new_nsp->pid_ns_for_children =
 93                 copy_pid_ns(flags, user_ns, tsk->nsproxy->pid_ns_for_children);
 94         if (IS_ERR(new_nsp->pid_ns_for_children)) {
 95                 err = PTR_ERR(new_nsp->pid_ns_for_children);
 96                 goto out_pid;
 97         }
 98 
 99         new_nsp->cgroup_ns = copy_cgroup_ns(flags, user_ns,
100                                             tsk->nsproxy->cgroup_ns);
101         if (IS_ERR(new_nsp->cgroup_ns)) {
102                 err = PTR_ERR(new_nsp->cgroup_ns);
103                 goto out_cgroup;
104         }
105 
106         new_nsp->net_ns = copy_net_ns(flags, user_ns, tsk->nsproxy->net_ns);
107         if (IS_ERR(new_nsp->net_ns)) {
108                 err = PTR_ERR(new_nsp->net_ns);
109                 goto out_net;
110         }
111 
112         return new_nsp;
113 
114 out_net:
115         put_cgroup_ns(new_nsp->cgroup_ns);
116 out_cgroup:
117         if (new_nsp->pid_ns_for_children)
118                 put_pid_ns(new_nsp->pid_ns_for_children);
119 out_pid:
120         if (new_nsp->ipc_ns)
121                 put_ipc_ns(new_nsp->ipc_ns);
122 out_ipc:
123         if (new_nsp->uts_ns)
124                 put_uts_ns(new_nsp->uts_ns);
125 out_uts:
126         if (new_nsp->mnt_ns)
127                 put_mnt_ns(new_nsp->mnt_ns);
128 out_ns:
129         kmem_cache_free(nsproxy_cachep, new_nsp);
130         return ERR_PTR(err);
131 }
132 
133 /*
134  * called from clone.  This now handles copy for nsproxy and all
135  * namespaces therein.
136  */
137 int copy_namespaces(unsigned long flags, struct task_struct *tsk)
138 {
139         struct nsproxy *old_ns = tsk->nsproxy;
140         struct user_namespace *user_ns = task_cred_xxx(tsk, user_ns);
141         struct nsproxy *new_ns;
142 
143         if (likely(!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
144                               CLONE_NEWPID | CLONE_NEWNET |
145                               CLONE_NEWCGROUP)))) {
146                 get_nsproxy(old_ns);
147                 return 0;
148         }
149 
150         if (!ns_capable(user_ns, CAP_SYS_ADMIN))
151                 return -EPERM;
152 
153         /*
154          * CLONE_NEWIPC must detach from the undolist: after switching
155          * to a new ipc namespace, the semaphore arrays from the old
156          * namespace are unreachable.  In clone parlance, CLONE_SYSVSEM
157          * means share undolist with parent, so we must forbid using
158          * it along with CLONE_NEWIPC.
159          */
160         if ((flags & (CLONE_NEWIPC | CLONE_SYSVSEM)) ==
161                 (CLONE_NEWIPC | CLONE_SYSVSEM)) 
162                 return -EINVAL;
163 
164         new_ns = create_new_namespaces(flags, tsk, user_ns, tsk->fs);
165         if (IS_ERR(new_ns))
166                 return  PTR_ERR(new_ns);
167 
168         tsk->nsproxy = new_ns;
169         return 0;
170 }
171 
172 void free_nsproxy(struct nsproxy *ns)
173 {
174         if (ns->mnt_ns)
175                 put_mnt_ns(ns->mnt_ns);
176         if (ns->uts_ns)
177                 put_uts_ns(ns->uts_ns);
178         if (ns->ipc_ns)
179                 put_ipc_ns(ns->ipc_ns);
180         if (ns->pid_ns_for_children)
181                 put_pid_ns(ns->pid_ns_for_children);
182         put_cgroup_ns(ns->cgroup_ns);
183         put_net(ns->net_ns);
184         kmem_cache_free(nsproxy_cachep, ns);
185 }
186 
187 /*
188  * Called from unshare. Unshare all the namespaces part of nsproxy.
189  * On success, returns the new nsproxy.
190  */
191 int unshare_nsproxy_namespaces(unsigned long unshare_flags,
192         struct nsproxy **new_nsp, struct cred *new_cred, struct fs_struct *new_fs)
193 {
194         struct user_namespace *user_ns;
195         int err = 0;
196 
197         if (!(unshare_flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
198                                CLONE_NEWNET | CLONE_NEWPID | CLONE_NEWCGROUP)))
199                 return 0;
200 
201         user_ns = new_cred ? new_cred->user_ns : current_user_ns();
202         if (!ns_capable(user_ns, CAP_SYS_ADMIN))
203                 return -EPERM;
204 
205         *new_nsp = create_new_namespaces(unshare_flags, current, user_ns,
206                                          new_fs ? new_fs : current->fs);
207         if (IS_ERR(*new_nsp)) {
208                 err = PTR_ERR(*new_nsp);
209                 goto out;
210         }
211 
212 out:
213         return err;
214 }
215 
216 void switch_task_namespaces(struct task_struct *p, struct nsproxy *new)
217 {
218         struct nsproxy *ns;
219 
220         might_sleep();
221 
222         task_lock(p);
223         ns = p->nsproxy;
224         p->nsproxy = new;
225         task_unlock(p);
226 
227         if (ns && atomic_dec_and_test(&ns->count))
228                 free_nsproxy(ns);
229 }
230 
231 void exit_task_namespaces(struct task_struct *p)
232 {
233         switch_task_namespaces(p, NULL);
234 }
235 
236 SYSCALL_DEFINE2(setns, int, fd, int, nstype)
237 {
238         struct task_struct *tsk = current;
239         struct nsproxy *new_nsproxy;
240         struct file *file;
241         struct ns_common *ns;
242         int err;
243 
244         file = proc_ns_fget(fd);
245         if (IS_ERR(file))
246                 return PTR_ERR(file);
247 
248         err = -EINVAL;
249         ns = get_proc_ns(file_inode(file));
250         if (nstype && (ns->ops->type != nstype))
251                 goto out;
252 
253         new_nsproxy = create_new_namespaces(0, tsk, current_user_ns(), tsk->fs);
254         if (IS_ERR(new_nsproxy)) {
255                 err = PTR_ERR(new_nsproxy);
256                 goto out;
257         }
258 
259         err = ns->ops->install(new_nsproxy, ns);
260         if (err) {
261                 free_nsproxy(new_nsproxy);
262                 goto out;
263         }
264         switch_task_namespaces(tsk, new_nsproxy);
265 out:
266         fput(file);
267         return err;
268 }
269 
270 int __init nsproxy_cache_init(void)
271 {
272         nsproxy_cachep = KMEM_CACHE(nsproxy, SLAB_PANIC);
273         return 0;
274 }
275 

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