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Merge tag 'iio-fixes-for-4.11c' of git://git.kernel.org/pub/scm/linux/kernel/git...
[mirror_ubuntu-bionic-kernel.git] / kernel / utsname.c
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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
9984de1a 12#include <linux/export.h>
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13#include <linux/uts.h>
14#include <linux/utsname.h>
467e9f4b 15#include <linux/err.h>
1aeb272c 16#include <linux/slab.h>
5b825c3a 17#include <linux/cred.h>
59607db3 18#include <linux/user_namespace.h>
0bb80f24 19#include <linux/proc_ns.h>
f719ff9b 20#include <linux/sched/task.h>
4865ecf1 21
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22static struct ucounts *inc_uts_namespaces(struct user_namespace *ns)
23{
24 return inc_ucount(ns, current_euid(), UCOUNT_UTS_NAMESPACES);
25}
26
27static void dec_uts_namespaces(struct ucounts *ucounts)
28{
29 dec_ucount(ucounts, UCOUNT_UTS_NAMESPACES);
30}
31
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32static struct uts_namespace *create_uts_ns(void)
33{
34 struct uts_namespace *uts_ns;
35
36 uts_ns = kmalloc(sizeof(struct uts_namespace), GFP_KERNEL);
37 if (uts_ns)
38 kref_init(&uts_ns->kref);
39 return uts_ns;
40}
41
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42/*
43 * Clone a new ns copying an original utsname, setting refcount to 1
44 * @old_ns: namespace to clone
bf531536 45 * Return ERR_PTR(-ENOMEM) on error (failure to kmalloc), new ns otherwise
071df104 46 */
bcf58e72 47static struct uts_namespace *clone_uts_ns(struct user_namespace *user_ns,
bb96a6f5 48 struct uts_namespace *old_ns)
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49{
50 struct uts_namespace *ns;
f7af3d1c 51 struct ucounts *ucounts;
98f842e6 52 int err;
071df104 53
df75e774 54 err = -ENOSPC;
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55 ucounts = inc_uts_namespaces(user_ns);
56 if (!ucounts)
57 goto fail;
58
59 err = -ENOMEM;
4c2a7e72 60 ns = create_uts_ns();
467e9f4b 61 if (!ns)
f7af3d1c 62 goto fail_dec;
467e9f4b 63
6344c433 64 err = ns_alloc_inum(&ns->ns);
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65 if (err)
66 goto fail_free;
98f842e6 67
f7af3d1c 68 ns->ucounts = ucounts;
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69 ns->ns.ops = &utsns_operations;
70
efc63c4f 71 down_read(&uts_sem);
467e9f4b 72 memcpy(&ns->name, &old_ns->name, sizeof(ns->name));
bcf58e72 73 ns->user_ns = get_user_ns(user_ns);
efc63c4f 74 up_read(&uts_sem);
071df104 75 return ns;
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76
77fail_free:
78 kfree(ns);
79fail_dec:
80 dec_uts_namespaces(ucounts);
81fail:
82 return ERR_PTR(err);
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83}
84
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85/*
86 * Copy task tsk's utsname namespace, or clone it if flags
87 * specifies CLONE_NEWUTS. In latter case, changes to the
88 * utsname of this process won't be seen by parent, and vice
89 * versa.
90 */
bb96a6f5 91struct uts_namespace *copy_utsname(unsigned long flags,
bcf58e72 92 struct user_namespace *user_ns, struct uts_namespace *old_ns)
4865ecf1 93{
071df104 94 struct uts_namespace *new_ns;
4865ecf1 95
e3222c4e 96 BUG_ON(!old_ns);
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97 get_uts_ns(old_ns);
98
071df104 99 if (!(flags & CLONE_NEWUTS))
e3222c4e 100 return old_ns;
071df104 101
bcf58e72 102 new_ns = clone_uts_ns(user_ns, old_ns);
071df104 103
071df104 104 put_uts_ns(old_ns);
e3222c4e 105 return new_ns;
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106}
107
108void free_uts_ns(struct kref *kref)
109{
110 struct uts_namespace *ns;
111
112 ns = container_of(kref, struct uts_namespace, kref);
f7af3d1c 113 dec_uts_namespaces(ns->ucounts);
59607db3 114 put_user_ns(ns->user_ns);
6344c433 115 ns_free_inum(&ns->ns);
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116 kfree(ns);
117}
34482e89 118
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119static inline struct uts_namespace *to_uts_ns(struct ns_common *ns)
120{
121 return container_of(ns, struct uts_namespace, ns);
122}
123
64964528 124static struct ns_common *utsns_get(struct task_struct *task)
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125{
126 struct uts_namespace *ns = NULL;
127 struct nsproxy *nsproxy;
128
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129 task_lock(task);
130 nsproxy = task->nsproxy;
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131 if (nsproxy) {
132 ns = nsproxy->uts_ns;
133 get_uts_ns(ns);
134 }
728dba3a 135 task_unlock(task);
34482e89 136
3c041184 137 return ns ? &ns->ns : NULL;
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138}
139
64964528 140static void utsns_put(struct ns_common *ns)
34482e89 141{
3c041184 142 put_uts_ns(to_uts_ns(ns));
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143}
144
64964528 145static int utsns_install(struct nsproxy *nsproxy, struct ns_common *new)
34482e89 146{
3c041184 147 struct uts_namespace *ns = to_uts_ns(new);
142e1d1d 148
5e4a0847 149 if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN) ||
c7b96acf 150 !ns_capable(current_user_ns(), CAP_SYS_ADMIN))
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151 return -EPERM;
152
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153 get_uts_ns(ns);
154 put_uts_ns(nsproxy->uts_ns);
155 nsproxy->uts_ns = ns;
156 return 0;
157}
158
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159static struct user_namespace *utsns_owner(struct ns_common *ns)
160{
161 return to_uts_ns(ns)->user_ns;
162}
163
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164const struct proc_ns_operations utsns_operations = {
165 .name = "uts",
166 .type = CLONE_NEWUTS,
167 .get = utsns_get,
168 .put = utsns_put,
169 .install = utsns_install,
bcac25a5 170 .owner = utsns_owner,
34482e89 171};