projects/linux·blob v4.0-rc1 · refs

139 lines · 3.0 KiB

1/*
2 * Copyright (C) 2004 IBM Corporation
3 *
4 * Author: Serge Hallyn <[email protected]>
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
20static 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 */
35static 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 */
66struct 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
83void 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
93static inline struct uts_namespace *to_uts_ns(struct ns_common *ns)
94{
95 return container_of(ns, struct uts_namespace, ns);
96}
97
98static 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
114static void utsns_put(struct ns_common *ns)
115{
116 put_uts_ns(to_uts_ns(ns));
117}
118
119static 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
133const 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};