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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_ns.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 ERR_PTR(-ENOMEM) on error (failure to kmalloc), new ns otherwise | |
34 | */ | |
35 | static struct uts_namespace *clone_uts_ns(struct user_namespace *user_ns, | |
36 | struct uts_namespace *old_ns) | |
37 | { | |
38 | struct uts_namespace *ns; | |
39 | int err; | |
40 | ||
41 | ns = create_uts_ns(); | |
42 | if (!ns) | |
43 | return ERR_PTR(-ENOMEM); | |
44 | ||
45 | err = ns_alloc_inum(&ns->ns); | |
46 | if (err) { | |
47 | kfree(ns); | |
48 | return ERR_PTR(err); | |
49 | } | |
50 | ||
51 | ns->ns.ops = &utsns_operations; | |
52 | ||
53 | down_read(&uts_sem); | |
54 | memcpy(&ns->name, &old_ns->name, sizeof(ns->name)); | |
55 | ns->user_ns = get_user_ns(user_ns); | |
56 | up_read(&uts_sem); | |
57 | return ns; | |
58 | } | |
59 | ||
60 | /* | |
61 | * Copy task tsk's utsname namespace, or clone it if flags | |
62 | * specifies CLONE_NEWUTS. In latter case, changes to the | |
63 | * utsname of this process won't be seen by parent, and vice | |
64 | * versa. | |
65 | */ | |
66 | struct uts_namespace *copy_utsname(unsigned long flags, | |
67 | struct user_namespace *user_ns, struct uts_namespace *old_ns) | |
68 | { | |
69 | struct uts_namespace *new_ns; | |
70 | ||
71 | BUG_ON(!old_ns); | |
72 | get_uts_ns(old_ns); | |
73 | ||
74 | if (!(flags & CLONE_NEWUTS)) | |
75 | return old_ns; | |
76 | ||
77 | new_ns = clone_uts_ns(user_ns, old_ns); | |
78 | ||
79 | put_uts_ns(old_ns); | |
80 | return new_ns; | |
81 | } | |
82 | ||
83 | void free_uts_ns(struct kref *kref) | |
84 | { | |
85 | struct uts_namespace *ns; | |
86 | ||
87 | ns = container_of(kref, struct uts_namespace, kref); | |
88 | put_user_ns(ns->user_ns); | |
89 | ns_free_inum(&ns->ns); | |
90 | kfree(ns); | |
91 | } | |
92 | ||
93 | static inline struct uts_namespace *to_uts_ns(struct ns_common *ns) | |
94 | { | |
95 | return container_of(ns, struct uts_namespace, ns); | |
96 | } | |
97 | ||
98 | static struct ns_common *utsns_get(struct task_struct *task) | |
99 | { | |
100 | struct uts_namespace *ns = NULL; | |
101 | struct nsproxy *nsproxy; | |
102 | ||
103 | task_lock(task); | |
104 | nsproxy = task->nsproxy; | |
105 | if (nsproxy) { | |
106 | ns = nsproxy->uts_ns; | |
107 | get_uts_ns(ns); | |
108 | } | |
109 | task_unlock(task); | |
110 | ||
111 | return ns ? &ns->ns : NULL; | |
112 | } | |
113 | ||
114 | static void utsns_put(struct ns_common *ns) | |
115 | { | |
116 | put_uts_ns(to_uts_ns(ns)); | |
117 | } | |
118 | ||
119 | static int utsns_install(struct nsproxy *nsproxy, struct ns_common *new) | |
120 | { | |
121 | struct uts_namespace *ns = to_uts_ns(new); | |
122 | ||
123 | if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN) || | |
124 | !ns_capable(current_user_ns(), CAP_SYS_ADMIN)) | |
125 | return -EPERM; | |
126 | ||
127 | get_uts_ns(ns); | |
128 | put_uts_ns(nsproxy->uts_ns); | |
129 | nsproxy->uts_ns = ns; | |
130 | return 0; | |
131 | } | |
132 | ||
133 | const struct proc_ns_operations utsns_operations = { | |
134 | .name = "uts", | |
135 | .type = CLONE_NEWUTS, | |
136 | .get = utsns_get, | |
137 | .put = utsns_put, | |
138 | .install = utsns_install, | |
139 | }; |