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1 | /* |
2 | * Copyright (C) 2004 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 | |
12 | #include <linux/export.h> |
13 | #include <linux/uts.h> |
14 | #include <linux/utsname.h> |
15 | #include <linux/err.h> |
16 | #include <linux/slab.h> |
17 | #include <linux/user_namespace.h> |
18 | #include <linux/proc_fs.h> |
19 | |
20 | static struct uts_namespace *create_uts_ns(void) |
21 | { |
22 | struct uts_namespace *uts_ns; |
23 | |
24 | uts_ns = kmalloc(sizeof(struct uts_namespace), GFP_KERNEL); |
25 | if (uts_ns) |
26 | kref_init(&uts_ns->kref); |
27 | return uts_ns; |
28 | } |
29 | |
30 | /* |
31 | * Clone a new ns copying an original utsname, setting refcount to 1 |
32 | * @old_ns: namespace to clone |
33 | * Return NULL on error (failure to kmalloc), new ns otherwise |
34 | */ |
35 | static struct uts_namespace *clone_uts_ns(struct task_struct *tsk, |
36 | struct uts_namespace *old_ns) |
37 | { |
38 | struct uts_namespace *ns; |
39 | |
40 | ns = create_uts_ns(); |
41 | if (!ns) |
42 | return ERR_PTR(-ENOMEM); |
43 | |
44 | down_read(&uts_sem); |
45 | memcpy(&ns->name, &old_ns->name, sizeof(ns->name)); |
46 | ns->user_ns = get_user_ns(task_cred_xxx(tsk, user_ns)); |
47 | up_read(&uts_sem); |
48 | return ns; |
49 | } |
50 | |
51 | /* |
52 | * Copy task tsk's utsname namespace, or clone it if flags |
53 | * specifies CLONE_NEWUTS. In latter case, changes to the |
54 | * utsname of this process won't be seen by parent, and vice |
55 | * versa. |
56 | */ |
57 | struct uts_namespace *copy_utsname(unsigned long flags, |
58 | struct task_struct *tsk) |
59 | { |
60 | struct uts_namespace *old_ns = tsk->nsproxy->uts_ns; |
61 | struct uts_namespace *new_ns; |
62 | |
63 | BUG_ON(!old_ns); |
64 | get_uts_ns(old_ns); |
65 | |
66 | if (!(flags & CLONE_NEWUTS)) |
67 | return old_ns; |
68 | |
69 | new_ns = clone_uts_ns(tsk, old_ns); |
70 | |
71 | put_uts_ns(old_ns); |
72 | return new_ns; |
73 | } |
74 | |
75 | void free_uts_ns(struct kref *kref) |
76 | { |
77 | struct uts_namespace *ns; |
78 | |
79 | ns = container_of(kref, struct uts_namespace, kref); |
80 | put_user_ns(ns->user_ns); |
81 | kfree(ns); |
82 | } |
83 | |
84 | static void *utsns_get(struct task_struct *task) |
85 | { |
86 | struct uts_namespace *ns = NULL; |
87 | struct nsproxy *nsproxy; |
88 | |
89 | rcu_read_lock(); |
90 | nsproxy = task_nsproxy(task); |
91 | if (nsproxy) { |
92 | ns = nsproxy->uts_ns; |
93 | get_uts_ns(ns); |
94 | } |
95 | rcu_read_unlock(); |
96 | |
97 | return ns; |
98 | } |
99 | |
100 | static void utsns_put(void *ns) |
101 | { |
102 | put_uts_ns(ns); |
103 | } |
104 | |
105 | static int utsns_install(struct nsproxy *nsproxy, void *ns) |
106 | { |
107 | get_uts_ns(ns); |
108 | put_uts_ns(nsproxy->uts_ns); |
109 | nsproxy->uts_ns = ns; |
110 | return 0; |
111 | } |
112 | |
113 | const struct proc_ns_operations utsns_operations = { |
114 | .name = "uts", |
115 | .type = CLONE_NEWUTS, |
116 | .get = utsns_get, |
117 | .put = utsns_put, |
118 | .install = utsns_install, |
119 | }; |
120 | |
121 |
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Tags:
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v2.6.34-rc5
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v3.9