xref: /openbmc/linux/kernel/nsproxy.c (revision ecd25094)
1  // SPDX-License-Identifier: GPL-2.0-only
2  /*
3   *  Copyright (C) 2006 IBM Corporation
4   *
5   *  Author: Serge Hallyn <serue@us.ibm.com>
6   *
7   *  Jun 2006 - namespaces support
8   *             OpenVZ, SWsoft Inc.
9   *             Pavel Emelianov <xemul@openvz.org>
10   */
11  
12  #include <linux/slab.h>
13  #include <linux/export.h>
14  #include <linux/nsproxy.h>
15  #include <linux/init_task.h>
16  #include <linux/mnt_namespace.h>
17  #include <linux/utsname.h>
18  #include <linux/pid_namespace.h>
19  #include <net/net_namespace.h>
20  #include <linux/ipc_namespace.h>
21  #include <linux/proc_ns.h>
22  #include <linux/file.h>
23  #include <linux/syscalls.h>
24  #include <linux/cgroup.h>
25  #include <linux/perf_event.h>
26  
27  static struct kmem_cache *nsproxy_cachep;
28  
29  struct nsproxy init_nsproxy = {
30  	.count			= ATOMIC_INIT(1),
31  	.uts_ns			= &init_uts_ns,
32  #if defined(CONFIG_POSIX_MQUEUE) || defined(CONFIG_SYSVIPC)
33  	.ipc_ns			= &init_ipc_ns,
34  #endif
35  	.mnt_ns			= NULL,
36  	.pid_ns_for_children	= &init_pid_ns,
37  #ifdef CONFIG_NET
38  	.net_ns			= &init_net,
39  #endif
40  #ifdef CONFIG_CGROUPS
41  	.cgroup_ns		= &init_cgroup_ns,
42  #endif
43  };
44  
45  static inline struct nsproxy *create_nsproxy(void)
46  {
47  	struct nsproxy *nsproxy;
48  
49  	nsproxy = kmem_cache_alloc(nsproxy_cachep, GFP_KERNEL);
50  	if (nsproxy)
51  		atomic_set(&nsproxy->count, 1);
52  	return nsproxy;
53  }
54  
55  /*
56   * Create new nsproxy and all of its the associated namespaces.
57   * Return the newly created nsproxy.  Do not attach this to the task,
58   * leave it to the caller to do proper locking and attach it to task.
59   */
60  static struct nsproxy *create_new_namespaces(unsigned long flags,
61  	struct task_struct *tsk, struct user_namespace *user_ns,
62  	struct fs_struct *new_fs)
63  {
64  	struct nsproxy *new_nsp;
65  	int err;
66  
67  	new_nsp = create_nsproxy();
68  	if (!new_nsp)
69  		return ERR_PTR(-ENOMEM);
70  
71  	new_nsp->mnt_ns = copy_mnt_ns(flags, tsk->nsproxy->mnt_ns, user_ns, new_fs);
72  	if (IS_ERR(new_nsp->mnt_ns)) {
73  		err = PTR_ERR(new_nsp->mnt_ns);
74  		goto out_ns;
75  	}
76  
77  	new_nsp->uts_ns = copy_utsname(flags, user_ns, tsk->nsproxy->uts_ns);
78  	if (IS_ERR(new_nsp->uts_ns)) {
79  		err = PTR_ERR(new_nsp->uts_ns);
80  		goto out_uts;
81  	}
82  
83  	new_nsp->ipc_ns = copy_ipcs(flags, user_ns, tsk->nsproxy->ipc_ns);
84  	if (IS_ERR(new_nsp->ipc_ns)) {
85  		err = PTR_ERR(new_nsp->ipc_ns);
86  		goto out_ipc;
87  	}
88  
89  	new_nsp->pid_ns_for_children =
90  		copy_pid_ns(flags, user_ns, tsk->nsproxy->pid_ns_for_children);
91  	if (IS_ERR(new_nsp->pid_ns_for_children)) {
92  		err = PTR_ERR(new_nsp->pid_ns_for_children);
93  		goto out_pid;
94  	}
95  
96  	new_nsp->cgroup_ns = copy_cgroup_ns(flags, user_ns,
97  					    tsk->nsproxy->cgroup_ns);
98  	if (IS_ERR(new_nsp->cgroup_ns)) {
99  		err = PTR_ERR(new_nsp->cgroup_ns);
100  		goto out_cgroup;
101  	}
102  
103  	new_nsp->net_ns = copy_net_ns(flags, user_ns, tsk->nsproxy->net_ns);
104  	if (IS_ERR(new_nsp->net_ns)) {
105  		err = PTR_ERR(new_nsp->net_ns);
106  		goto out_net;
107  	}
108  
109  	return new_nsp;
110  
111  out_net:
112  	put_cgroup_ns(new_nsp->cgroup_ns);
113  out_cgroup:
114  	if (new_nsp->pid_ns_for_children)
115  		put_pid_ns(new_nsp->pid_ns_for_children);
116  out_pid:
117  	if (new_nsp->ipc_ns)
118  		put_ipc_ns(new_nsp->ipc_ns);
119  out_ipc:
120  	if (new_nsp->uts_ns)
121  		put_uts_ns(new_nsp->uts_ns);
122  out_uts:
123  	if (new_nsp->mnt_ns)
124  		put_mnt_ns(new_nsp->mnt_ns);
125  out_ns:
126  	kmem_cache_free(nsproxy_cachep, new_nsp);
127  	return ERR_PTR(err);
128  }
129  
130  /*
131   * called from clone.  This now handles copy for nsproxy and all
132   * namespaces therein.
133   */
134  int copy_namespaces(unsigned long flags, struct task_struct *tsk)
135  {
136  	struct nsproxy *old_ns = tsk->nsproxy;
137  	struct user_namespace *user_ns = task_cred_xxx(tsk, user_ns);
138  	struct nsproxy *new_ns;
139  
140  	if (likely(!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
141  			      CLONE_NEWPID | CLONE_NEWNET |
142  			      CLONE_NEWCGROUP)))) {
143  		get_nsproxy(old_ns);
144  		return 0;
145  	}
146  
147  	if (!ns_capable(user_ns, CAP_SYS_ADMIN))
148  		return -EPERM;
149  
150  	/*
151  	 * CLONE_NEWIPC must detach from the undolist: after switching
152  	 * to a new ipc namespace, the semaphore arrays from the old
153  	 * namespace are unreachable.  In clone parlance, CLONE_SYSVSEM
154  	 * means share undolist with parent, so we must forbid using
155  	 * it along with CLONE_NEWIPC.
156  	 */
157  	if ((flags & (CLONE_NEWIPC | CLONE_SYSVSEM)) ==
158  		(CLONE_NEWIPC | CLONE_SYSVSEM))
159  		return -EINVAL;
160  
161  	new_ns = create_new_namespaces(flags, tsk, user_ns, tsk->fs);
162  	if (IS_ERR(new_ns))
163  		return  PTR_ERR(new_ns);
164  
165  	tsk->nsproxy = new_ns;
166  	return 0;
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_for_children)
178  		put_pid_ns(ns->pid_ns_for_children);
179  	put_cgroup_ns(ns->cgroup_ns);
180  	put_net(ns->net_ns);
181  	kmem_cache_free(nsproxy_cachep, ns);
182  }
183  
184  /*
185   * Called from unshare. Unshare all the namespaces part of nsproxy.
186   * On success, returns the new nsproxy.
187   */
188  int unshare_nsproxy_namespaces(unsigned long unshare_flags,
189  	struct nsproxy **new_nsp, struct cred *new_cred, struct fs_struct *new_fs)
190  {
191  	struct user_namespace *user_ns;
192  	int err = 0;
193  
194  	if (!(unshare_flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
195  			       CLONE_NEWNET | CLONE_NEWPID | CLONE_NEWCGROUP)))
196  		return 0;
197  
198  	user_ns = new_cred ? new_cred->user_ns : current_user_ns();
199  	if (!ns_capable(user_ns, CAP_SYS_ADMIN))
200  		return -EPERM;
201  
202  	*new_nsp = create_new_namespaces(unshare_flags, current, user_ns,
203  					 new_fs ? new_fs : current->fs);
204  	if (IS_ERR(*new_nsp)) {
205  		err = PTR_ERR(*new_nsp);
206  		goto out;
207  	}
208  
209  out:
210  	return err;
211  }
212  
213  void switch_task_namespaces(struct task_struct *p, struct nsproxy *new)
214  {
215  	struct nsproxy *ns;
216  
217  	might_sleep();
218  
219  	task_lock(p);
220  	ns = p->nsproxy;
221  	p->nsproxy = new;
222  	task_unlock(p);
223  
224  	if (ns && atomic_dec_and_test(&ns->count))
225  		free_nsproxy(ns);
226  }
227  
228  void exit_task_namespaces(struct task_struct *p)
229  {
230  	switch_task_namespaces(p, NULL);
231  }
232  
233  SYSCALL_DEFINE2(setns, int, fd, int, nstype)
234  {
235  	struct task_struct *tsk = current;
236  	struct nsproxy *new_nsproxy;
237  	struct file *file;
238  	struct ns_common *ns;
239  	int err;
240  
241  	file = proc_ns_fget(fd);
242  	if (IS_ERR(file))
243  		return PTR_ERR(file);
244  
245  	err = -EINVAL;
246  	ns = get_proc_ns(file_inode(file));
247  	if (nstype && (ns->ops->type != nstype))
248  		goto out;
249  
250  	new_nsproxy = create_new_namespaces(0, tsk, current_user_ns(), tsk->fs);
251  	if (IS_ERR(new_nsproxy)) {
252  		err = PTR_ERR(new_nsproxy);
253  		goto out;
254  	}
255  
256  	err = ns->ops->install(new_nsproxy, ns);
257  	if (err) {
258  		free_nsproxy(new_nsproxy);
259  		goto out;
260  	}
261  	switch_task_namespaces(tsk, new_nsproxy);
262  
263  	perf_event_namespaces(tsk);
264  out:
265  	fput(file);
266  	return err;
267  }
268  
269  int __init nsproxy_cache_init(void)
270  {
271  	nsproxy_cachep = KMEM_CACHE(nsproxy, SLAB_PANIC);
272  	return 0;
273  }
274