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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/module.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 | |
26 | static struct kmem_cache *nsproxy_cachep; |
27 | |
28 | struct nsproxy init_nsproxy = { |
29 | .count = ATOMIC_INIT(1), |
30 | .uts_ns = &init_uts_ns, |
31 | #if defined(CONFIG_POSIX_MQUEUE) || defined(CONFIG_SYSVIPC) |
32 | .ipc_ns = &init_ipc_ns, |
33 | #endif |
34 | .mnt_ns = NULL, |
35 | .pid_ns = &init_pid_ns, |
36 | #ifdef CONFIG_NET |
37 | .net_ns = &init_net, |
38 | #endif |
39 | }; |
40 | |
41 | static inline struct nsproxy *create_nsproxy(void) |
42 | { |
43 | struct nsproxy *nsproxy; |
44 | |
45 | nsproxy = kmem_cache_alloc(nsproxy_cachep, GFP_KERNEL); |
46 | if (nsproxy) |
47 | atomic_set(&nsproxy->count, 1); |
48 | return nsproxy; |
49 | } |
50 | |
51 | /* |
52 | * Create new nsproxy and all of its the associated namespaces. |
53 | * Return the newly created nsproxy. Do not attach this to the task, |
54 | * leave it to the caller to do proper locking and attach it to task. |
55 | */ |
56 | static struct nsproxy *create_new_namespaces(unsigned long flags, |
57 | struct task_struct *tsk, struct fs_struct *new_fs) |
58 | { |
59 | struct nsproxy *new_nsp; |
60 | int err; |
61 | |
62 | new_nsp = create_nsproxy(); |
63 | if (!new_nsp) |
64 | return ERR_PTR(-ENOMEM); |
65 | |
66 | new_nsp->mnt_ns = copy_mnt_ns(flags, tsk->nsproxy->mnt_ns, new_fs); |
67 | if (IS_ERR(new_nsp->mnt_ns)) { |
68 | err = PTR_ERR(new_nsp->mnt_ns); |
69 | goto out_ns; |
70 | } |
71 | |
72 | new_nsp->uts_ns = copy_utsname(flags, tsk->nsproxy->uts_ns); |
73 | if (IS_ERR(new_nsp->uts_ns)) { |
74 | err = PTR_ERR(new_nsp->uts_ns); |
75 | goto out_uts; |
76 | } |
77 | |
78 | new_nsp->ipc_ns = copy_ipcs(flags, tsk->nsproxy->ipc_ns); |
79 | if (IS_ERR(new_nsp->ipc_ns)) { |
80 | err = PTR_ERR(new_nsp->ipc_ns); |
81 | goto out_ipc; |
82 | } |
83 | |
84 | new_nsp->pid_ns = copy_pid_ns(flags, task_active_pid_ns(tsk)); |
85 | if (IS_ERR(new_nsp->pid_ns)) { |
86 | err = PTR_ERR(new_nsp->pid_ns); |
87 | goto out_pid; |
88 | } |
89 | |
90 | new_nsp->net_ns = copy_net_ns(flags, tsk->nsproxy->net_ns); |
91 | if (IS_ERR(new_nsp->net_ns)) { |
92 | err = PTR_ERR(new_nsp->net_ns); |
93 | goto out_net; |
94 | } |
95 | |
96 | return new_nsp; |
97 | |
98 | out_net: |
99 | if (new_nsp->pid_ns) |
100 | put_pid_ns(new_nsp->pid_ns); |
101 | out_pid: |
102 | if (new_nsp->ipc_ns) |
103 | put_ipc_ns(new_nsp->ipc_ns); |
104 | out_ipc: |
105 | if (new_nsp->uts_ns) |
106 | put_uts_ns(new_nsp->uts_ns); |
107 | out_uts: |
108 | if (new_nsp->mnt_ns) |
109 | put_mnt_ns(new_nsp->mnt_ns); |
110 | out_ns: |
111 | kmem_cache_free(nsproxy_cachep, new_nsp); |
112 | return ERR_PTR(err); |
113 | } |
114 | |
115 | /* |
116 | * called from clone. This now handles copy for nsproxy and all |
117 | * namespaces therein. |
118 | */ |
119 | int copy_namespaces(unsigned long flags, struct task_struct *tsk) |
120 | { |
121 | struct nsproxy *old_ns = tsk->nsproxy; |
122 | struct nsproxy *new_ns; |
123 | int err = 0; |
124 | |
125 | if (!old_ns) |
126 | return 0; |
127 | |
128 | get_nsproxy(old_ns); |
129 | |
130 | if (!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC | |
131 | CLONE_NEWPID | CLONE_NEWNET))) |
132 | return 0; |
133 | |
134 | if (!capable(CAP_SYS_ADMIN)) { |
135 | err = -EPERM; |
136 | goto out; |
137 | } |
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) && (flags & CLONE_SYSVSEM)) { |
147 | err = -EINVAL; |
148 | goto out; |
149 | } |
150 | |
151 | new_ns = create_new_namespaces(flags, tsk, tsk->fs); |
152 | if (IS_ERR(new_ns)) { |
153 | err = PTR_ERR(new_ns); |
154 | goto out; |
155 | } |
156 | |
157 | tsk->nsproxy = new_ns; |
158 | |
159 | out: |
160 | put_nsproxy(old_ns); |
161 | return err; |
162 | } |
163 | |
164 | void free_nsproxy(struct nsproxy *ns) |
165 | { |
166 | if (ns->mnt_ns) |
167 | put_mnt_ns(ns->mnt_ns); |
168 | if (ns->uts_ns) |
169 | put_uts_ns(ns->uts_ns); |
170 | if (ns->ipc_ns) |
171 | put_ipc_ns(ns->ipc_ns); |
172 | if (ns->pid_ns) |
173 | put_pid_ns(ns->pid_ns); |
174 | put_net(ns->net_ns); |
175 | kmem_cache_free(nsproxy_cachep, ns); |
176 | } |
177 | |
178 | /* |
179 | * Called from unshare. Unshare all the namespaces part of nsproxy. |
180 | * On success, returns the new nsproxy. |
181 | */ |
182 | int unshare_nsproxy_namespaces(unsigned long unshare_flags, |
183 | struct nsproxy **new_nsp, struct fs_struct *new_fs) |
184 | { |
185 | int err = 0; |
186 | |
187 | if (!(unshare_flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC | |
188 | CLONE_NEWNET))) |
189 | return 0; |
190 | |
191 | if (!capable(CAP_SYS_ADMIN)) |
192 | return -EPERM; |
193 | |
194 | *new_nsp = create_new_namespaces(unshare_flags, current, |
195 | new_fs ? new_fs : current->fs); |
196 | if (IS_ERR(*new_nsp)) { |
197 | err = PTR_ERR(*new_nsp); |
198 | goto out; |
199 | } |
200 | |
201 | err = ns_cgroup_clone(current, task_pid(current)); |
202 | if (err) |
203 | put_nsproxy(*new_nsp); |
204 | |
205 | out: |
206 | return err; |
207 | } |
208 | |
209 | void switch_task_namespaces(struct task_struct *p, struct nsproxy *new) |
210 | { |
211 | struct nsproxy *ns; |
212 | |
213 | might_sleep(); |
214 | |
215 | ns = p->nsproxy; |
216 | |
217 | rcu_assign_pointer(p->nsproxy, new); |
218 | |
219 | if (ns && atomic_dec_and_test(&ns->count)) { |
220 | /* |
221 | * wait for others to get what they want from this nsproxy. |
222 | * |
223 | * cannot release this nsproxy via the call_rcu() since |
224 | * put_mnt_ns() will want to sleep |
225 | */ |
226 | synchronize_rcu(); |
227 | free_nsproxy(ns); |
228 | } |
229 | } |
230 | |
231 | void exit_task_namespaces(struct task_struct *p) |
232 | { |
233 | switch_task_namespaces(p, NULL); |
234 | } |
235 | |
236 | static int __init nsproxy_cache_init(void) |
237 | { |
238 | nsproxy_cachep = KMEM_CACHE(nsproxy, SLAB_PANIC); |
239 | return 0; |
240 | } |
241 | |
242 | module_init(nsproxy_cache_init); |
243 |
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