• Home
  • Line#
  • Scopes#
  • Navigate#
  • Raw
  • Download
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 
create_nsproxy(void)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  */
create_new_namespaces(unsigned long flags,struct task_struct * tsk,struct user_namespace * user_ns,struct fs_struct * new_fs)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  */
copy_namespaces(unsigned long flags,struct task_struct * tsk)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 
free_nsproxy(struct nsproxy * ns)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  */
unshare_nsproxy_namespaces(unsigned long unshare_flags,struct nsproxy ** new_nsp,struct cred * new_cred,struct fs_struct * new_fs)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 
switch_task_namespaces(struct task_struct * p,struct nsproxy * new)201 void switch_task_namespaces(struct task_struct *p, struct nsproxy *new)
202 {
203 	struct nsproxy *ns;
204 
205 	might_sleep();
206 
207 	task_lock(p);
208 	ns = p->nsproxy;
209 	p->nsproxy = new;
210 	task_unlock(p);
211 
212 	if (ns && atomic_dec_and_test(&ns->count))
213 		free_nsproxy(ns);
214 }
215 
exit_task_namespaces(struct task_struct * p)216 void exit_task_namespaces(struct task_struct *p)
217 {
218 	switch_task_namespaces(p, NULL);
219 }
220 
SYSCALL_DEFINE2(setns,int,fd,int,nstype)221 SYSCALL_DEFINE2(setns, int, fd, int, nstype)
222 {
223 	const struct proc_ns_operations *ops;
224 	struct task_struct *tsk = current;
225 	struct nsproxy *new_nsproxy;
226 	struct proc_ns *ei;
227 	struct file *file;
228 	int err;
229 
230 	file = proc_ns_fget(fd);
231 	if (IS_ERR(file))
232 		return PTR_ERR(file);
233 
234 	err = -EINVAL;
235 	ei = get_proc_ns(file_inode(file));
236 	ops = ei->ns_ops;
237 	if (nstype && (ops->type != nstype))
238 		goto out;
239 
240 	new_nsproxy = create_new_namespaces(0, tsk, current_user_ns(), tsk->fs);
241 	if (IS_ERR(new_nsproxy)) {
242 		err = PTR_ERR(new_nsproxy);
243 		goto out;
244 	}
245 
246 	err = ops->install(new_nsproxy, ei->ns);
247 	if (err) {
248 		free_nsproxy(new_nsproxy);
249 		goto out;
250 	}
251 	switch_task_namespaces(tsk, new_nsproxy);
252 out:
253 	fput(file);
254 	return err;
255 }
256 
nsproxy_cache_init(void)257 int __init nsproxy_cache_init(void)
258 {
259 	nsproxy_cachep = KMEM_CACHE(nsproxy, SLAB_PANIC);
260 	return 0;
261 }
262