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
create_nsproxy(void)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 */
create_new_namespaces(unsigned long flags,struct task_struct * tsk,struct user_namespace * user_ns,struct fs_struct * new_fs)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 */
copy_namespaces(unsigned long flags,struct task_struct * tsk)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
free_nsproxy(struct nsproxy * ns)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 */
unshare_nsproxy_namespaces(unsigned long unshare_flags,struct nsproxy ** new_nsp,struct cred * new_cred,struct fs_struct * new_fs)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
switch_task_namespaces(struct task_struct * p,struct nsproxy * new)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
exit_task_namespaces(struct task_struct * p)228 void exit_task_namespaces(struct task_struct *p)
229 {
230 switch_task_namespaces(p, NULL);
231 }
232
SYSCALL_DEFINE2(setns,int,fd,int,nstype)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
nsproxy_cache_init(void)269 int __init nsproxy_cache_init(void)
270 {
271 nsproxy_cachep = KMEM_CACHE(nsproxy, SLAB_PANIC);
272 return 0;
273 }
274