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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 | ||
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 | */ | |
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 | */ | |
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 | ||
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 | */ | |
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 | ||
201 | void switch_task_namespaces(struct task_struct *p, struct nsproxy *new) | |
202 | { | |
203 | struct nsproxy *ns; | |
204 | ||
205 | might_sleep(); | |
206 | ||
207 | ns = p->nsproxy; | |
208 | ||
209 | rcu_assign_pointer(p->nsproxy, new); | |
210 | ||
211 | if (ns && atomic_dec_and_test(&ns->count)) { | |
212 | /* | |
213 | * wait for others to get what they want from this nsproxy. | |
214 | * | |
215 | * cannot release this nsproxy via the call_rcu() since | |
216 | * put_mnt_ns() will want to sleep | |
217 | */ | |
218 | synchronize_rcu(); | |
219 | free_nsproxy(ns); | |
220 | } | |
221 | } | |
222 | ||
223 | void exit_task_namespaces(struct task_struct *p) | |
224 | { | |
225 | switch_task_namespaces(p, NULL); | |
226 | } | |
227 | ||
228 | SYSCALL_DEFINE2(setns, int, fd, int, nstype) | |
229 | { | |
230 | const struct proc_ns_operations *ops; | |
231 | struct task_struct *tsk = current; | |
232 | struct nsproxy *new_nsproxy; | |
233 | struct proc_ns *ei; | |
234 | struct file *file; | |
235 | int err; | |
236 | ||
237 | file = proc_ns_fget(fd); | |
238 | if (IS_ERR(file)) | |
239 | return PTR_ERR(file); | |
240 | ||
241 | err = -EINVAL; | |
242 | ei = get_proc_ns(file_inode(file)); | |
243 | ops = ei->ns_ops; | |
244 | if (nstype && (ops->type != nstype)) | |
245 | goto out; | |
246 | ||
247 | new_nsproxy = create_new_namespaces(0, tsk, current_user_ns(), tsk->fs); | |
248 | if (IS_ERR(new_nsproxy)) { | |
249 | err = PTR_ERR(new_nsproxy); | |
250 | goto out; | |
251 | } | |
252 | ||
253 | err = ops->install(new_nsproxy, ei->ns); | |
254 | if (err) { | |
255 | free_nsproxy(new_nsproxy); | |
256 | goto out; | |
257 | } | |
258 | switch_task_namespaces(tsk, new_nsproxy); | |
259 | out: | |
260 | fput(file); | |
261 | return err; | |
262 | } | |
263 | ||
264 | int __init nsproxy_cache_init(void) | |
265 | { | |
266 | nsproxy_cachep = KMEM_CACHE(nsproxy, SLAB_PANIC); | |
267 | return 0; | |
268 | } |