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Merge branches 'clk-qcom-rpmh', 'clk-npcm7xx', 'clk-of-parent-count' and 'clk-qcom...
[mirror_ubuntu-eoan-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 kmem_cache *uts_ns_cache __ro_after_init;
23
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24static struct ucounts *inc_uts_namespaces(struct user_namespace *ns)
25{
26 return inc_ucount(ns, current_euid(), UCOUNT_UTS_NAMESPACES);
27}
28
29static void dec_uts_namespaces(struct ucounts *ucounts)
30{
31 dec_ucount(ucounts, UCOUNT_UTS_NAMESPACES);
32}
33
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34static struct uts_namespace *create_uts_ns(void)
35{
36 struct uts_namespace *uts_ns;
37
3ea056c5 38 uts_ns = kmem_cache_alloc(uts_ns_cache, GFP_KERNEL);
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39 if (uts_ns)
40 kref_init(&uts_ns->kref);
41 return uts_ns;
42}
43
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44/*
45 * Clone a new ns copying an original utsname, setting refcount to 1
46 * @old_ns: namespace to clone
3ea056c5 47 * Return ERR_PTR(-ENOMEM) on error (failure to allocate), new ns otherwise
071df104 48 */
bcf58e72 49static struct uts_namespace *clone_uts_ns(struct user_namespace *user_ns,
bb96a6f5 50 struct uts_namespace *old_ns)
071df104
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51{
52 struct uts_namespace *ns;
f7af3d1c 53 struct ucounts *ucounts;
98f842e6 54 int err;
071df104 55
df75e774 56 err = -ENOSPC;
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57 ucounts = inc_uts_namespaces(user_ns);
58 if (!ucounts)
59 goto fail;
60
61 err = -ENOMEM;
4c2a7e72 62 ns = create_uts_ns();
467e9f4b 63 if (!ns)
f7af3d1c 64 goto fail_dec;
467e9f4b 65
6344c433 66 err = ns_alloc_inum(&ns->ns);
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67 if (err)
68 goto fail_free;
98f842e6 69
f7af3d1c 70 ns->ucounts = ucounts;
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71 ns->ns.ops = &utsns_operations;
72
efc63c4f 73 down_read(&uts_sem);
467e9f4b 74 memcpy(&ns->name, &old_ns->name, sizeof(ns->name));
bcf58e72 75 ns->user_ns = get_user_ns(user_ns);
efc63c4f 76 up_read(&uts_sem);
071df104 77 return ns;
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78
79fail_free:
3ea056c5 80 kmem_cache_free(uts_ns_cache, ns);
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81fail_dec:
82 dec_uts_namespaces(ucounts);
83fail:
84 return ERR_PTR(err);
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85}
86
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87/*
88 * Copy task tsk's utsname namespace, or clone it if flags
89 * specifies CLONE_NEWUTS. In latter case, changes to the
90 * utsname of this process won't be seen by parent, and vice
91 * versa.
92 */
bb96a6f5 93struct uts_namespace *copy_utsname(unsigned long flags,
bcf58e72 94 struct user_namespace *user_ns, struct uts_namespace *old_ns)
4865ecf1 95{
071df104 96 struct uts_namespace *new_ns;
4865ecf1 97
e3222c4e 98 BUG_ON(!old_ns);
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99 get_uts_ns(old_ns);
100
071df104 101 if (!(flags & CLONE_NEWUTS))
e3222c4e 102 return old_ns;
071df104 103
bcf58e72 104 new_ns = clone_uts_ns(user_ns, old_ns);
071df104 105
071df104 106 put_uts_ns(old_ns);
e3222c4e 107 return new_ns;
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108}
109
110void free_uts_ns(struct kref *kref)
111{
112 struct uts_namespace *ns;
113
114 ns = container_of(kref, struct uts_namespace, kref);
f7af3d1c 115 dec_uts_namespaces(ns->ucounts);
59607db3 116 put_user_ns(ns->user_ns);
6344c433 117 ns_free_inum(&ns->ns);
3ea056c5 118 kmem_cache_free(uts_ns_cache, ns);
4865ecf1 119}
34482e89 120
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121static inline struct uts_namespace *to_uts_ns(struct ns_common *ns)
122{
123 return container_of(ns, struct uts_namespace, ns);
124}
125
64964528 126static struct ns_common *utsns_get(struct task_struct *task)
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127{
128 struct uts_namespace *ns = NULL;
129 struct nsproxy *nsproxy;
130
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131 task_lock(task);
132 nsproxy = task->nsproxy;
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133 if (nsproxy) {
134 ns = nsproxy->uts_ns;
135 get_uts_ns(ns);
136 }
728dba3a 137 task_unlock(task);
34482e89 138
3c041184 139 return ns ? &ns->ns : NULL;
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140}
141
64964528 142static void utsns_put(struct ns_common *ns)
34482e89 143{
3c041184 144 put_uts_ns(to_uts_ns(ns));
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145}
146
64964528 147static int utsns_install(struct nsproxy *nsproxy, struct ns_common *new)
34482e89 148{
3c041184 149 struct uts_namespace *ns = to_uts_ns(new);
142e1d1d 150
5e4a0847 151 if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN) ||
c7b96acf 152 !ns_capable(current_user_ns(), CAP_SYS_ADMIN))
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153 return -EPERM;
154
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155 get_uts_ns(ns);
156 put_uts_ns(nsproxy->uts_ns);
157 nsproxy->uts_ns = ns;
158 return 0;
159}
160
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161static struct user_namespace *utsns_owner(struct ns_common *ns)
162{
163 return to_uts_ns(ns)->user_ns;
164}
165
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166const struct proc_ns_operations utsns_operations = {
167 .name = "uts",
168 .type = CLONE_NEWUTS,
169 .get = utsns_get,
170 .put = utsns_put,
171 .install = utsns_install,
bcac25a5 172 .owner = utsns_owner,
34482e89 173};
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174
175void __init uts_ns_init(void)
176{
177 uts_ns_cache = kmem_cache_create_usercopy(
178 "uts_namespace", sizeof(struct uts_namespace), 0,
179 SLAB_PANIC|SLAB_ACCOUNT,
180 offsetof(struct uts_namespace, name),
181 sizeof_field(struct uts_namespace, name),
182 NULL);
183}