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 #include <linux/perf_event.h>
30 
31 static struct kmem_cache *nsproxy_cachep;
32 
33 struct nsproxy init_nsproxy = {
34 	.count			= ATOMIC_INIT(1),
35 	.uts_ns			= &init_uts_ns,
36 #if defined(CONFIG_POSIX_MQUEUE) || defined(CONFIG_SYSVIPC)
37 	.ipc_ns			= &init_ipc_ns,
38 #endif
39 	.mnt_ns			= NULL,
40 	.pid_ns_for_children	= &init_pid_ns,
41 #ifdef CONFIG_NET
42 	.net_ns			= &init_net,
43 #endif
44 #ifdef CONFIG_CGROUPS
45 	.cgroup_ns		= &init_cgroup_ns,
46 #endif
47 };
48 
create_nsproxy(void)49 static inline struct nsproxy *create_nsproxy(void)
50 {
51 	struct nsproxy *nsproxy;
52 
53 	nsproxy = kmem_cache_alloc(nsproxy_cachep, GFP_KERNEL);
54 	if (nsproxy)
55 		atomic_set(&nsproxy->count, 1);
56 	return nsproxy;
57 }
58 
59 /*
60  * Create new nsproxy and all of its the associated namespaces.
61  * Return the newly created nsproxy.  Do not attach this to the task,
62  * leave it to the caller to do proper locking and attach it to task.
63  */
create_new_namespaces(unsigned long flags,struct task_struct * tsk,struct user_namespace * user_ns,struct fs_struct * new_fs)64 static struct nsproxy *create_new_namespaces(unsigned long flags,
65 	struct task_struct *tsk, struct user_namespace *user_ns,
66 	struct fs_struct *new_fs)
67 {
68 	struct nsproxy *new_nsp;
69 	int err;
70 
71 	new_nsp = create_nsproxy();
72 	if (!new_nsp)
73 		return ERR_PTR(-ENOMEM);
74 
75 	new_nsp->mnt_ns = copy_mnt_ns(flags, tsk->nsproxy->mnt_ns, user_ns, new_fs);
76 	if (IS_ERR(new_nsp->mnt_ns)) {
77 		err = PTR_ERR(new_nsp->mnt_ns);
78 		goto out_ns;
79 	}
80 
81 	new_nsp->uts_ns = copy_utsname(flags, user_ns, tsk->nsproxy->uts_ns);
82 	if (IS_ERR(new_nsp->uts_ns)) {
83 		err = PTR_ERR(new_nsp->uts_ns);
84 		goto out_uts;
85 	}
86 
87 	new_nsp->ipc_ns = copy_ipcs(flags, user_ns, tsk->nsproxy->ipc_ns);
88 	if (IS_ERR(new_nsp->ipc_ns)) {
89 		err = PTR_ERR(new_nsp->ipc_ns);
90 		goto out_ipc;
91 	}
92 
93 	new_nsp->pid_ns_for_children =
94 		copy_pid_ns(flags, user_ns, tsk->nsproxy->pid_ns_for_children);
95 	if (IS_ERR(new_nsp->pid_ns_for_children)) {
96 		err = PTR_ERR(new_nsp->pid_ns_for_children);
97 		goto out_pid;
98 	}
99 
100 	new_nsp->cgroup_ns = copy_cgroup_ns(flags, user_ns,
101 					    tsk->nsproxy->cgroup_ns);
102 	if (IS_ERR(new_nsp->cgroup_ns)) {
103 		err = PTR_ERR(new_nsp->cgroup_ns);
104 		goto out_cgroup;
105 	}
106 
107 	new_nsp->net_ns = copy_net_ns(flags, user_ns, tsk->nsproxy->net_ns);
108 	if (IS_ERR(new_nsp->net_ns)) {
109 		err = PTR_ERR(new_nsp->net_ns);
110 		goto out_net;
111 	}
112 
113 	return new_nsp;
114 
115 out_net:
116 	put_cgroup_ns(new_nsp->cgroup_ns);
117 out_cgroup:
118 	if (new_nsp->pid_ns_for_children)
119 		put_pid_ns(new_nsp->pid_ns_for_children);
120 out_pid:
121 	if (new_nsp->ipc_ns)
122 		put_ipc_ns(new_nsp->ipc_ns);
123 out_ipc:
124 	if (new_nsp->uts_ns)
125 		put_uts_ns(new_nsp->uts_ns);
126 out_uts:
127 	if (new_nsp->mnt_ns)
128 		put_mnt_ns(new_nsp->mnt_ns);
129 out_ns:
130 	kmem_cache_free(nsproxy_cachep, new_nsp);
131 	return ERR_PTR(err);
132 }
133 
134 /*
135  * called from clone.  This now handles copy for nsproxy and all
136  * namespaces therein.
137  */
copy_namespaces(unsigned long flags,struct task_struct * tsk)138 int copy_namespaces(unsigned long flags, struct task_struct *tsk)
139 {
140 	struct nsproxy *old_ns = tsk->nsproxy;
141 	struct user_namespace *user_ns = task_cred_xxx(tsk, user_ns);
142 	struct nsproxy *new_ns;
143 
144 	if (likely(!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
145 			      CLONE_NEWPID | CLONE_NEWNET |
146 			      CLONE_NEWCGROUP)))) {
147 		get_nsproxy(old_ns);
148 		return 0;
149 	}
150 
151 	if (!ns_capable(user_ns, CAP_SYS_ADMIN))
152 		return -EPERM;
153 
154 	/*
155 	 * CLONE_NEWIPC must detach from the undolist: after switching
156 	 * to a new ipc namespace, the semaphore arrays from the old
157 	 * namespace are unreachable.  In clone parlance, CLONE_SYSVSEM
158 	 * means share undolist with parent, so we must forbid using
159 	 * it along with CLONE_NEWIPC.
160 	 */
161 	if ((flags & (CLONE_NEWIPC | CLONE_SYSVSEM)) ==
162 		(CLONE_NEWIPC | CLONE_SYSVSEM))
163 		return -EINVAL;
164 
165 	new_ns = create_new_namespaces(flags, tsk, user_ns, tsk->fs);
166 	if (IS_ERR(new_ns))
167 		return  PTR_ERR(new_ns);
168 
169 	tsk->nsproxy = new_ns;
170 	return 0;
171 }
172 
free_nsproxy(struct nsproxy * ns)173 void free_nsproxy(struct nsproxy *ns)
174 {
175 	if (ns->mnt_ns)
176 		put_mnt_ns(ns->mnt_ns);
177 	if (ns->uts_ns)
178 		put_uts_ns(ns->uts_ns);
179 	if (ns->ipc_ns)
180 		put_ipc_ns(ns->ipc_ns);
181 	if (ns->pid_ns_for_children)
182 		put_pid_ns(ns->pid_ns_for_children);
183 	put_cgroup_ns(ns->cgroup_ns);
184 	put_net(ns->net_ns);
185 	kmem_cache_free(nsproxy_cachep, ns);
186 }
187 
188 /*
189  * Called from unshare. Unshare all the namespaces part of nsproxy.
190  * On success, returns the new nsproxy.
191  */
unshare_nsproxy_namespaces(unsigned long unshare_flags,struct nsproxy ** new_nsp,struct cred * new_cred,struct fs_struct * new_fs)192 int unshare_nsproxy_namespaces(unsigned long unshare_flags,
193 	struct nsproxy **new_nsp, struct cred *new_cred, struct fs_struct *new_fs)
194 {
195 	struct user_namespace *user_ns;
196 	int err = 0;
197 
198 	if (!(unshare_flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
199 			       CLONE_NEWNET | CLONE_NEWPID | CLONE_NEWCGROUP)))
200 		return 0;
201 
202 	user_ns = new_cred ? new_cred->user_ns : current_user_ns();
203 	if (!ns_capable(user_ns, CAP_SYS_ADMIN))
204 		return -EPERM;
205 
206 	*new_nsp = create_new_namespaces(unshare_flags, current, user_ns,
207 					 new_fs ? new_fs : current->fs);
208 	if (IS_ERR(*new_nsp)) {
209 		err = PTR_ERR(*new_nsp);
210 		goto out;
211 	}
212 
213 out:
214 	return err;
215 }
216 
switch_task_namespaces(struct task_struct * p,struct nsproxy * new)217 void switch_task_namespaces(struct task_struct *p, struct nsproxy *new)
218 {
219 	struct nsproxy *ns;
220 
221 	might_sleep();
222 
223 	task_lock(p);
224 	ns = p->nsproxy;
225 	p->nsproxy = new;
226 	task_unlock(p);
227 
228 	if (ns && atomic_dec_and_test(&ns->count))
229 		free_nsproxy(ns);
230 }
231 
exit_task_namespaces(struct task_struct * p)232 void exit_task_namespaces(struct task_struct *p)
233 {
234 	switch_task_namespaces(p, NULL);
235 }
236 
SYSCALL_DEFINE2(setns,int,fd,int,nstype)237 SYSCALL_DEFINE2(setns, int, fd, int, nstype)
238 {
239 	struct task_struct *tsk = current;
240 	struct nsproxy *new_nsproxy;
241 	struct file *file;
242 	struct ns_common *ns;
243 	int err;
244 
245 	file = proc_ns_fget(fd);
246 	if (IS_ERR(file))
247 		return PTR_ERR(file);
248 
249 	err = -EINVAL;
250 	ns = get_proc_ns(file_inode(file));
251 	if (nstype && (ns->ops->type != nstype))
252 		goto out;
253 
254 	new_nsproxy = create_new_namespaces(0, tsk, current_user_ns(), tsk->fs);
255 	if (IS_ERR(new_nsproxy)) {
256 		err = PTR_ERR(new_nsproxy);
257 		goto out;
258 	}
259 
260 	err = ns->ops->install(new_nsproxy, ns);
261 	if (err) {
262 		free_nsproxy(new_nsproxy);
263 		goto out;
264 	}
265 	switch_task_namespaces(tsk, new_nsproxy);
266 
267 	perf_event_namespaces(tsk);
268 out:
269 	fput(file);
270 	return err;
271 }
272 
nsproxy_cache_init(void)273 int __init nsproxy_cache_init(void)
274 {
275 	nsproxy_cachep = KMEM_CACHE(nsproxy, SLAB_PANIC);
276 	return 0;
277 }
278