1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 *  Copyright (C) 2004 IBM Corporation
  4 *
  5 *  Author: Serge Hallyn <serue@us.ibm.com>
  6 */
  7
  8#include <linux/export.h>
  9#include <linux/uts.h>
 10#include <linux/utsname.h>
 11#include <linux/err.h>
 12#include <linux/slab.h>
 13#include <linux/cred.h>
 14#include <linux/user_namespace.h>
 15#include <linux/proc_ns.h>
 16#include <linux/sched/task.h>
 17
 18static struct kmem_cache *uts_ns_cache __ro_after_init;
 19
 20static 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
 30static struct uts_namespace *create_uts_ns(void)
 31{
 32	struct uts_namespace *uts_ns;
 33
 34	uts_ns = kmem_cache_alloc(uts_ns_cache, GFP_KERNEL);
 35	if (uts_ns)
 36		refcount_set(&uts_ns->ns.count, 1);
 37	return uts_ns;
 38}
 39
 40/*
 41 * Clone a new ns copying an original utsname, setting refcount to 1
 42 * @old_ns: namespace to clone
 43 * Return ERR_PTR(-ENOMEM) on error (failure to allocate), new ns otherwise
 44 */
 45static struct uts_namespace *clone_uts_ns(struct user_namespace *user_ns,
 46					  struct uts_namespace *old_ns)
 47{
 48	struct uts_namespace *ns;
 49	struct ucounts *ucounts;
 50	int err;
 51
 52	err = -ENOSPC;
 53	ucounts = inc_uts_namespaces(user_ns);
 54	if (!ucounts)
 55		goto fail;
 56
 57	err = -ENOMEM;
 58	ns = create_uts_ns();
 59	if (!ns)
 60		goto fail_dec;
 61
 62	err = ns_alloc_inum(&ns->ns);
 63	if (err)
 64		goto fail_free;
 65
 66	ns->ucounts = ucounts;
 67	ns->ns.ops = &utsns_operations;
 68
 69	down_read(&uts_sem);
 70	memcpy(&ns->name, &old_ns->name, sizeof(ns->name));
 71	ns->user_ns = get_user_ns(user_ns);
 72	up_read(&uts_sem);
 73	return ns;
 74
 75fail_free:
 76	kmem_cache_free(uts_ns_cache, ns);
 77fail_dec:
 78	dec_uts_namespaces(ucounts);
 79fail:
 80	return ERR_PTR(err);
 81}
 82
 83/*
 84 * 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 */
 89struct uts_namespace *copy_utsname(unsigned long flags,
 90	struct user_namespace *user_ns, struct uts_namespace *old_ns)
 91{
 92	struct uts_namespace *new_ns;
 93
 94	BUG_ON(!old_ns);
 95	get_uts_ns(old_ns);
 96
 97	if (!(flags & CLONE_NEWUTS))
 98		return old_ns;
 99
100	new_ns = clone_uts_ns(user_ns, old_ns);
101
102	put_uts_ns(old_ns);
103	return new_ns;
104}
105
106void free_uts_ns(struct uts_namespace *ns)
107{
108	dec_uts_namespaces(ns->ucounts);
109	put_user_ns(ns->user_ns);
110	ns_free_inum(&ns->ns);
111	kmem_cache_free(uts_ns_cache, ns);
112}
113
114static inline struct uts_namespace *to_uts_ns(struct ns_common *ns)
115{
116	return container_of(ns, struct uts_namespace, ns);
117}
118
119static struct ns_common *utsns_get(struct task_struct *task)
120{
121	struct uts_namespace *ns = NULL;
122	struct nsproxy *nsproxy;
123
124	task_lock(task);
125	nsproxy = task->nsproxy;
126	if (nsproxy) {
127		ns = nsproxy->uts_ns;
128		get_uts_ns(ns);
129	}
130	task_unlock(task);
131
132	return ns ? &ns->ns : NULL;
133}
134
135static void utsns_put(struct ns_common *ns)
136{
137	put_uts_ns(to_uts_ns(ns));
138}
139
140static int utsns_install(struct nsset *nsset, struct ns_common *new)
141{
142	struct nsproxy *nsproxy = nsset->nsproxy;
143	struct uts_namespace *ns = to_uts_ns(new);
144
145	if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN) ||
146	    !ns_capable(nsset->cred->user_ns, CAP_SYS_ADMIN))
147		return -EPERM;
148
149	get_uts_ns(ns);
150	put_uts_ns(nsproxy->uts_ns);
151	nsproxy->uts_ns = ns;
152	return 0;
153}
154
155static struct user_namespace *utsns_owner(struct ns_common *ns)
156{
157	return to_uts_ns(ns)->user_ns;
158}
159
160const 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,
166	.owner		= utsns_owner,
167};
168
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}

  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/module.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_fs.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 NULL on error (failure to kmalloc), new ns otherwise
 34 */
 35static struct uts_namespace *clone_uts_ns(struct task_struct *tsk,
 36					  struct uts_namespace *old_ns)
 37{
 38	struct uts_namespace *ns;
 39
 40	ns = create_uts_ns();
 41	if (!ns)
 42		return ERR_PTR(-ENOMEM);
 43
 44	down_read(&uts_sem);
 45	memcpy(&ns->name, &old_ns->name, sizeof(ns->name));
 46	ns->user_ns = get_user_ns(task_cred_xxx(tsk, user)->user_ns);
 47	up_read(&uts_sem);
 48	return ns;
 49}
 50
 51/*
 52 * Copy task tsk's utsname namespace, or clone it if flags
 53 * specifies CLONE_NEWUTS.  In latter case, changes to the
 54 * utsname of this process won't be seen by parent, and vice
 55 * versa.
 56 */
 57struct uts_namespace *copy_utsname(unsigned long flags,
 58				   struct task_struct *tsk)
 59{
 60	struct uts_namespace *old_ns = tsk->nsproxy->uts_ns;
 61	struct uts_namespace *new_ns;
 62
 63	BUG_ON(!old_ns);
 64	get_uts_ns(old_ns);
 65
 66	if (!(flags & CLONE_NEWUTS))
 67		return old_ns;
 68
 69	new_ns = clone_uts_ns(tsk, old_ns);
 70
 71	put_uts_ns(old_ns);
 72	return new_ns;
 73}
 74
 75void free_uts_ns(struct kref *kref)
 76{
 77	struct uts_namespace *ns;
 78
 79	ns = container_of(kref, struct uts_namespace, kref);
 80	put_user_ns(ns->user_ns);
 81	kfree(ns);
 82}
 83
 84static void *utsns_get(struct task_struct *task)
 85{
 86	struct uts_namespace *ns = NULL;
 87	struct nsproxy *nsproxy;
 88
 89	rcu_read_lock();
 90	nsproxy = task_nsproxy(task);
 91	if (nsproxy) {
 92		ns = nsproxy->uts_ns;
 93		get_uts_ns(ns);
 94	}
 95	rcu_read_unlock();
 96
 97	return ns;
 98}
 99
100static void utsns_put(void *ns)
101{
102	put_uts_ns(ns);
103}
104
105static int utsns_install(struct nsproxy *nsproxy, void *ns)
106{
107	get_uts_ns(ns);
108	put_uts_ns(nsproxy->uts_ns);
109	nsproxy->uts_ns = ns;
110	return 0;
111}
112
113const struct proc_ns_operations utsns_operations = {
114	.name		= "uts",
115	.type		= CLONE_NEWUTS,
116	.get		= utsns_get,
117	.put		= utsns_put,
118	.install	= utsns_install,
119};
120