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Thomas Gleixnerb886d83c2019-06-01 10:08:55 +02001// SPDX-License-Identifier: GPL-2.0-only
Serge E. Hallyn4865ecf2006-10-02 02:18:14 -07002/*
3 * Copyright (C) 2004 IBM Corporation
4 *
5 * Author: Serge Hallyn <serue@us.ibm.com>
Serge E. Hallyn4865ecf2006-10-02 02:18:14 -07006 */
7
Paul Gortmaker9984de12011-05-23 14:51:41 -04008#include <linux/export.h>
Serge E. Hallyn4865ecf2006-10-02 02:18:14 -07009#include <linux/uts.h>
10#include <linux/utsname.h>
Cedric Le Goater467e9f42007-07-15 23:41:06 -070011#include <linux/err.h>
Robert P. J. Day1aeb2722008-04-29 00:59:25 -070012#include <linux/slab.h>
Ingo Molnar5b825c32017-02-02 17:54:15 +010013#include <linux/cred.h>
Serge E. Hallyn59607db2011-03-23 16:43:16 -070014#include <linux/user_namespace.h>
David Howells0bb80f22013-04-12 01:50:06 +010015#include <linux/proc_ns.h>
Ingo Molnarf719ff9b2017-02-06 10:57:33 +010016#include <linux/sched/task.h>
Serge E. Hallyn4865ecf2006-10-02 02:18:14 -070017
Alexey Dobriyan3ea056c2018-04-10 16:32:36 -070018static struct kmem_cache *uts_ns_cache __ro_after_init;
19
Eric W. Biedermanf7af3d12016-08-08 14:11:25 -050020static struct ucounts *inc_uts_namespaces(struct user_namespace *ns)
21{
22 return inc_ucount(ns, current_euid(), UCOUNT_UTS_NAMESPACES);
23}
24
25static void dec_uts_namespaces(struct ucounts *ucounts)
26{
27 dec_ucount(ucounts, UCOUNT_UTS_NAMESPACES);
28}
29
Alexey Dobriyan4c2a7e72009-06-17 16:27:54 -070030static struct uts_namespace *create_uts_ns(void)
31{
32 struct uts_namespace *uts_ns;
33
Alexey Dobriyan3ea056c2018-04-10 16:32:36 -070034 uts_ns = kmem_cache_alloc(uts_ns_cache, GFP_KERNEL);
Alexey Dobriyan4c2a7e72009-06-17 16:27:54 -070035 if (uts_ns)
Kirill Tkhai9a564932020-08-03 13:16:21 +030036 refcount_set(&uts_ns->ns.count, 1);
Alexey Dobriyan4c2a7e72009-06-17 16:27:54 -070037 return uts_ns;
38}
39
Serge E. Hallyn4865ecf2006-10-02 02:18:14 -070040/*
Serge E. Hallyn071df1042006-10-02 02:18:17 -070041 * Clone a new ns copying an original utsname, setting refcount to 1
42 * @old_ns: namespace to clone
Alexey Dobriyan3ea056c2018-04-10 16:32:36 -070043 * Return ERR_PTR(-ENOMEM) on error (failure to allocate), new ns otherwise
Serge E. Hallyn071df1042006-10-02 02:18:17 -070044 */
Eric W. Biedermanbcf58e72012-07-26 04:02:49 -070045static struct uts_namespace *clone_uts_ns(struct user_namespace *user_ns,
Serge E. Hallynbb96a6f2011-03-23 16:43:18 -070046 struct uts_namespace *old_ns)
Serge E. Hallyn071df1042006-10-02 02:18:17 -070047{
48 struct uts_namespace *ns;
Eric W. Biedermanf7af3d12016-08-08 14:11:25 -050049 struct ucounts *ucounts;
Eric W. Biederman98f842e2011-06-15 10:21:48 -070050 int err;
Serge E. Hallyn071df1042006-10-02 02:18:17 -070051
Eric W. Biedermandf75e772016-09-22 13:08:36 -050052 err = -ENOSPC;
Eric W. Biedermanf7af3d12016-08-08 14:11:25 -050053 ucounts = inc_uts_namespaces(user_ns);
54 if (!ucounts)
55 goto fail;
56
57 err = -ENOMEM;
Alexey Dobriyan4c2a7e72009-06-17 16:27:54 -070058 ns = create_uts_ns();
Cedric Le Goater467e9f42007-07-15 23:41:06 -070059 if (!ns)
Eric W. Biedermanf7af3d12016-08-08 14:11:25 -050060 goto fail_dec;
Cedric Le Goater467e9f42007-07-15 23:41:06 -070061
Al Viro6344c432014-11-01 00:45:45 -040062 err = ns_alloc_inum(&ns->ns);
Eric W. Biedermanf7af3d12016-08-08 14:11:25 -050063 if (err)
64 goto fail_free;
Eric W. Biederman98f842e2011-06-15 10:21:48 -070065
Eric W. Biedermanf7af3d12016-08-08 14:11:25 -050066 ns->ucounts = ucounts;
Al Viro33c42942014-11-01 02:32:53 -040067 ns->ns.ops = &utsns_operations;
68
Alexey Dobriyanefc63c42007-09-18 22:46:27 -070069 down_read(&uts_sem);
Cedric Le Goater467e9f42007-07-15 23:41:06 -070070 memcpy(&ns->name, &old_ns->name, sizeof(ns->name));
Eric W. Biedermanbcf58e72012-07-26 04:02:49 -070071 ns->user_ns = get_user_ns(user_ns);
Alexey Dobriyanefc63c42007-09-18 22:46:27 -070072 up_read(&uts_sem);
Serge E. Hallyn071df1042006-10-02 02:18:17 -070073 return ns;
Eric W. Biedermanf7af3d12016-08-08 14:11:25 -050074
75fail_free:
Alexey Dobriyan3ea056c2018-04-10 16:32:36 -070076 kmem_cache_free(uts_ns_cache, ns);
Eric W. Biedermanf7af3d12016-08-08 14:11:25 -050077fail_dec:
78 dec_uts_namespaces(ucounts);
79fail:
80 return ERR_PTR(err);
Serge E. Hallyn071df1042006-10-02 02:18:17 -070081}
82
83/*
Serge E. Hallyn4865ecf2006-10-02 02:18:14 -070084 * Copy task tsk's utsname namespace, or clone it if flags
85 * specifies CLONE_NEWUTS. In latter case, changes to the
86 * utsname of this process won't be seen by parent, and vice
87 * versa.
88 */
Serge E. Hallynbb96a6f2011-03-23 16:43:18 -070089struct uts_namespace *copy_utsname(unsigned long flags,
Eric W. Biedermanbcf58e72012-07-26 04:02:49 -070090 struct user_namespace *user_ns, struct uts_namespace *old_ns)
Serge E. Hallyn4865ecf2006-10-02 02:18:14 -070091{
Serge E. Hallyn071df1042006-10-02 02:18:17 -070092 struct uts_namespace *new_ns;
Serge E. Hallyn4865ecf2006-10-02 02:18:14 -070093
Badari Pulavartye3222c42007-05-08 00:25:21 -070094 BUG_ON(!old_ns);
Serge E. Hallyn4865ecf2006-10-02 02:18:14 -070095 get_uts_ns(old_ns);
96
Serge E. Hallyn071df1042006-10-02 02:18:17 -070097 if (!(flags & CLONE_NEWUTS))
Badari Pulavartye3222c42007-05-08 00:25:21 -070098 return old_ns;
Serge E. Hallyn071df1042006-10-02 02:18:17 -070099
Eric W. Biedermanbcf58e72012-07-26 04:02:49 -0700100 new_ns = clone_uts_ns(user_ns, old_ns);
Serge E. Hallyn071df1042006-10-02 02:18:17 -0700101
Serge E. Hallyn071df1042006-10-02 02:18:17 -0700102 put_uts_ns(old_ns);
Badari Pulavartye3222c42007-05-08 00:25:21 -0700103 return new_ns;
Serge E. Hallyn4865ecf2006-10-02 02:18:14 -0700104}
105
Kirill Tkhai9a564932020-08-03 13:16:21 +0300106void free_uts_ns(struct uts_namespace *ns)
Serge E. Hallyn4865ecf2006-10-02 02:18:14 -0700107{
Eric W. Biedermanf7af3d12016-08-08 14:11:25 -0500108 dec_uts_namespaces(ns->ucounts);
Serge E. Hallyn59607db2011-03-23 16:43:16 -0700109 put_user_ns(ns->user_ns);
Al Viro6344c432014-11-01 00:45:45 -0400110 ns_free_inum(&ns->ns);
Alexey Dobriyan3ea056c2018-04-10 16:32:36 -0700111 kmem_cache_free(uts_ns_cache, ns);
Serge E. Hallyn4865ecf2006-10-02 02:18:14 -0700112}
Eric W. Biederman34482e82010-03-07 18:43:27 -0800113
Al Viro3c041182014-11-01 00:25:30 -0400114static inline struct uts_namespace *to_uts_ns(struct ns_common *ns)
115{
116 return container_of(ns, struct uts_namespace, ns);
117}
118
Al Viro64964522014-11-01 00:37:32 -0400119static struct ns_common *utsns_get(struct task_struct *task)
Eric W. Biederman34482e82010-03-07 18:43:27 -0800120{
121 struct uts_namespace *ns = NULL;
122 struct nsproxy *nsproxy;
123
Eric W. Biederman728dba32014-02-03 19:13:49 -0800124 task_lock(task);
125 nsproxy = task->nsproxy;
Eric W. Biederman34482e82010-03-07 18:43:27 -0800126 if (nsproxy) {
127 ns = nsproxy->uts_ns;
128 get_uts_ns(ns);
129 }
Eric W. Biederman728dba32014-02-03 19:13:49 -0800130 task_unlock(task);
Eric W. Biederman34482e82010-03-07 18:43:27 -0800131
Al Viro3c041182014-11-01 00:25:30 -0400132 return ns ? &ns->ns : NULL;
Eric W. Biederman34482e82010-03-07 18:43:27 -0800133}
134
Al Viro64964522014-11-01 00:37:32 -0400135static void utsns_put(struct ns_common *ns)
Eric W. Biederman34482e82010-03-07 18:43:27 -0800136{
Al Viro3c041182014-11-01 00:25:30 -0400137 put_uts_ns(to_uts_ns(ns));
Eric W. Biederman34482e82010-03-07 18:43:27 -0800138}
139
Christian Braunerf2a8d522020-05-05 16:04:30 +0200140static int utsns_install(struct nsset *nsset, struct ns_common *new)
Eric W. Biederman34482e82010-03-07 18:43:27 -0800141{
Christian Braunerf2a8d522020-05-05 16:04:30 +0200142 struct nsproxy *nsproxy = nsset->nsproxy;
Al Viro3c041182014-11-01 00:25:30 -0400143 struct uts_namespace *ns = to_uts_ns(new);
Eric W. Biederman142e1d12012-07-26 01:13:20 -0700144
Eric W. Biederman5e4a0842012-12-14 07:55:36 -0800145 if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN) ||
Christian Braunerf2a8d522020-05-05 16:04:30 +0200146 !ns_capable(nsset->cred->user_ns, CAP_SYS_ADMIN))
Eric W. Biederman142e1d12012-07-26 01:13:20 -0700147 return -EPERM;
148
Eric W. Biederman34482e82010-03-07 18:43:27 -0800149 get_uts_ns(ns);
150 put_uts_ns(nsproxy->uts_ns);
151 nsproxy->uts_ns = ns;
152 return 0;
153}
154
Andrey Vaginbcac25a2016-09-06 00:47:13 -0700155static struct user_namespace *utsns_owner(struct ns_common *ns)
156{
157 return to_uts_ns(ns)->user_ns;
158}
159
Eric W. Biederman34482e82010-03-07 18:43:27 -0800160const struct proc_ns_operations utsns_operations = {
161 .name = "uts",
162 .type = CLONE_NEWUTS,
163 .get = utsns_get,
164 .put = utsns_put,
165 .install = utsns_install,
Andrey Vaginbcac25a2016-09-06 00:47:13 -0700166 .owner = utsns_owner,
Eric W. Biederman34482e82010-03-07 18:43:27 -0800167};
Alexey Dobriyan3ea056c2018-04-10 16:32:36 -0700168
169void __init uts_ns_init(void)
170{
171 uts_ns_cache = kmem_cache_create_usercopy(
172 "uts_namespace", sizeof(struct uts_namespace), 0,
173 SLAB_PANIC|SLAB_ACCOUNT,
174 offsetof(struct uts_namespace, name),
175 sizeof_field(struct uts_namespace, name),
176 NULL);
177}