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// 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		kref_init(&uts_ns->kref);
 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 kref *kref)
107{
108	struct uts_namespace *ns;
109
110	ns = container_of(kref, struct uts_namespace, kref);
111	dec_uts_namespaces(ns->ucounts);
112	put_user_ns(ns->user_ns);
113	ns_free_inum(&ns->ns);
114	kmem_cache_free(uts_ns_cache, ns);
115}
116
117static inline struct uts_namespace *to_uts_ns(struct ns_common *ns)
118{
119	return container_of(ns, struct uts_namespace, ns);
120}
121
122static struct ns_common *utsns_get(struct task_struct *task)
123{
124	struct uts_namespace *ns = NULL;
125	struct nsproxy *nsproxy;
126
127	task_lock(task);
128	nsproxy = task->nsproxy;
129	if (nsproxy) {
130		ns = nsproxy->uts_ns;
131		get_uts_ns(ns);
132	}
133	task_unlock(task);
134
135	return ns ? &ns->ns : NULL;
136}
137
138static void utsns_put(struct ns_common *ns)
139{
140	put_uts_ns(to_uts_ns(ns));
141}
142
143static int utsns_install(struct nsproxy *nsproxy, struct ns_common *new)
144{
145	struct uts_namespace *ns = to_uts_ns(new);
146
147	if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN) ||
148	    !ns_capable(current_user_ns(), CAP_SYS_ADMIN))
149		return -EPERM;
150
151	get_uts_ns(ns);
152	put_uts_ns(nsproxy->uts_ns);
153	nsproxy->uts_ns = ns;
154	return 0;
155}
156
157static struct user_namespace *utsns_owner(struct ns_common *ns)
158{
159	return to_uts_ns(ns)->user_ns;
 
 
160}
161
162const struct proc_ns_operations utsns_operations = {
163	.name		= "uts",
164	.type		= CLONE_NEWUTS,
165	.get		= utsns_get,
166	.put		= utsns_put,
167	.install	= utsns_install,
168	.owner		= utsns_owner,
169};
170
171void __init uts_ns_init(void)
172{
173	uts_ns_cache = kmem_cache_create_usercopy(
174			"uts_namespace", sizeof(struct uts_namespace), 0,
175			SLAB_PANIC|SLAB_ACCOUNT,
176			offsetof(struct uts_namespace, name),
177			sizeof_field(struct uts_namespace, name),
178			NULL);
179}