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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
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 = proc_alloc_inum(&ns->proc_inum);
46 if (err) {
47 kfree(ns);
48 return ERR_PTR(err);
49 }
50
51 down_read(&uts_sem);
52 memcpy(&ns->name, &old_ns->name, sizeof(ns->name));
53 ns->user_ns = get_user_ns(user_ns);
54 up_read(&uts_sem);
55 return ns;
56}
57
58/*
59 * Copy task tsk's utsname namespace, or clone it if flags
60 * specifies CLONE_NEWUTS. In latter case, changes to the
61 * utsname of this process won't be seen by parent, and vice
62 * versa.
63 */
64struct uts_namespace *copy_utsname(unsigned long flags,
65 struct user_namespace *user_ns, struct uts_namespace *old_ns)
66{
67 struct uts_namespace *new_ns;
68
69 BUG_ON(!old_ns);
70 get_uts_ns(old_ns);
71
72 if (!(flags & CLONE_NEWUTS))
73 return old_ns;
74
75 new_ns = clone_uts_ns(user_ns, old_ns);
76
77 put_uts_ns(old_ns);
78 return new_ns;
79}
80
81void free_uts_ns(struct kref *kref)
82{
83 struct uts_namespace *ns;
84
85 ns = container_of(kref, struct uts_namespace, kref);
86 put_user_ns(ns->user_ns);
87 proc_free_inum(ns->proc_inum);
88 kfree(ns);
89}
90
91static void *utsns_get(struct task_struct *task)
92{
93 struct uts_namespace *ns = NULL;
94 struct nsproxy *nsproxy;
95
96 rcu_read_lock();
97 nsproxy = task_nsproxy(task);
98 if (nsproxy) {
99 ns = nsproxy->uts_ns;
100 get_uts_ns(ns);
101 }
102 rcu_read_unlock();
103
104 return ns;
105}
106
107static void utsns_put(void *ns)
108{
109 put_uts_ns(ns);
110}
111
112static int utsns_install(struct nsproxy *nsproxy, void *new)
113{
114 struct uts_namespace *ns = new;
115
116 if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN) ||
117 !ns_capable(current_user_ns(), CAP_SYS_ADMIN))
118 return -EPERM;
119
120 get_uts_ns(ns);
121 put_uts_ns(nsproxy->uts_ns);
122 nsproxy->uts_ns = ns;
123 return 0;
124}
125
126static unsigned int utsns_inum(void *vp)
127{
128 struct uts_namespace *ns = vp;
129
130 return ns->proc_inum;
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 .inum = utsns_inum,
140};
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/cred.h>
18#include <linux/user_namespace.h>
19#include <linux/proc_ns.h>
20#include <linux/sched/task.h>
21
22static struct kmem_cache *uts_ns_cache __ro_after_init;
23
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
34static struct uts_namespace *create_uts_ns(void)
35{
36 struct uts_namespace *uts_ns;
37
38 uts_ns = kmem_cache_alloc(uts_ns_cache, GFP_KERNEL);
39 if (uts_ns)
40 kref_init(&uts_ns->kref);
41 return uts_ns;
42}
43
44/*
45 * Clone a new ns copying an original utsname, setting refcount to 1
46 * @old_ns: namespace to clone
47 * Return ERR_PTR(-ENOMEM) on error (failure to allocate), new ns otherwise
48 */
49static struct uts_namespace *clone_uts_ns(struct user_namespace *user_ns,
50 struct uts_namespace *old_ns)
51{
52 struct uts_namespace *ns;
53 struct ucounts *ucounts;
54 int err;
55
56 err = -ENOSPC;
57 ucounts = inc_uts_namespaces(user_ns);
58 if (!ucounts)
59 goto fail;
60
61 err = -ENOMEM;
62 ns = create_uts_ns();
63 if (!ns)
64 goto fail_dec;
65
66 err = ns_alloc_inum(&ns->ns);
67 if (err)
68 goto fail_free;
69
70 ns->ucounts = ucounts;
71 ns->ns.ops = &utsns_operations;
72
73 down_read(&uts_sem);
74 memcpy(&ns->name, &old_ns->name, sizeof(ns->name));
75 ns->user_ns = get_user_ns(user_ns);
76 up_read(&uts_sem);
77 return ns;
78
79fail_free:
80 kmem_cache_free(uts_ns_cache, ns);
81fail_dec:
82 dec_uts_namespaces(ucounts);
83fail:
84 return ERR_PTR(err);
85}
86
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 */
93struct uts_namespace *copy_utsname(unsigned long flags,
94 struct user_namespace *user_ns, struct uts_namespace *old_ns)
95{
96 struct uts_namespace *new_ns;
97
98 BUG_ON(!old_ns);
99 get_uts_ns(old_ns);
100
101 if (!(flags & CLONE_NEWUTS))
102 return old_ns;
103
104 new_ns = clone_uts_ns(user_ns, old_ns);
105
106 put_uts_ns(old_ns);
107 return new_ns;
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);
115 dec_uts_namespaces(ns->ucounts);
116 put_user_ns(ns->user_ns);
117 ns_free_inum(&ns->ns);
118 kmem_cache_free(uts_ns_cache, ns);
119}
120
121static inline struct uts_namespace *to_uts_ns(struct ns_common *ns)
122{
123 return container_of(ns, struct uts_namespace, ns);
124}
125
126static struct ns_common *utsns_get(struct task_struct *task)
127{
128 struct uts_namespace *ns = NULL;
129 struct nsproxy *nsproxy;
130
131 task_lock(task);
132 nsproxy = task->nsproxy;
133 if (nsproxy) {
134 ns = nsproxy->uts_ns;
135 get_uts_ns(ns);
136 }
137 task_unlock(task);
138
139 return ns ? &ns->ns : NULL;
140}
141
142static void utsns_put(struct ns_common *ns)
143{
144 put_uts_ns(to_uts_ns(ns));
145}
146
147static int utsns_install(struct nsproxy *nsproxy, struct ns_common *new)
148{
149 struct uts_namespace *ns = to_uts_ns(new);
150
151 if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN) ||
152 !ns_capable(current_user_ns(), CAP_SYS_ADMIN))
153 return -EPERM;
154
155 get_uts_ns(ns);
156 put_uts_ns(nsproxy->uts_ns);
157 nsproxy->uts_ns = ns;
158 return 0;
159}
160
161static struct user_namespace *utsns_owner(struct ns_common *ns)
162{
163 return to_uts_ns(ns)->user_ns;
164}
165
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,
172 .owner = utsns_owner,
173};
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}