1 // SPDX-License-Identifier: GPL-2.0-only
3 * Copyright (C) 2004 IBM Corporation
5 * Author: Serge Hallyn <serue@us.ibm.com>
8 #include <linux/export.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>
18 static struct kmem_cache *uts_ns_cache __ro_after_init;
20 static struct ucounts *inc_uts_namespaces(struct user_namespace *ns)
22 return inc_ucount(ns, current_euid(), UCOUNT_UTS_NAMESPACES);
25 static void dec_uts_namespaces(struct ucounts *ucounts)
27 dec_ucount(ucounts, UCOUNT_UTS_NAMESPACES);
30 static struct uts_namespace *create_uts_ns(void)
32 struct uts_namespace *uts_ns;
34 uts_ns = kmem_cache_alloc(uts_ns_cache, GFP_KERNEL);
36 refcount_set(&uts_ns->ns.count, 1);
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
45 static struct uts_namespace *clone_uts_ns(struct user_namespace *user_ns,
46 struct uts_namespace *old_ns)
48 struct uts_namespace *ns;
49 struct ucounts *ucounts;
53 ucounts = inc_uts_namespaces(user_ns);
62 err = ns_alloc_inum(&ns->ns);
66 ns->ucounts = ucounts;
67 ns->ns.ops = &utsns_operations;
70 memcpy(&ns->name, &old_ns->name, sizeof(ns->name));
71 ns->user_ns = get_user_ns(user_ns);
76 kmem_cache_free(uts_ns_cache, ns);
78 dec_uts_namespaces(ucounts);
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
89 struct uts_namespace *copy_utsname(unsigned long flags,
90 struct user_namespace *user_ns, struct uts_namespace *old_ns)
92 struct uts_namespace *new_ns;
97 if (!(flags & CLONE_NEWUTS))
100 new_ns = clone_uts_ns(user_ns, old_ns);
106 void free_uts_ns(struct uts_namespace *ns)
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);
114 static inline struct uts_namespace *to_uts_ns(struct ns_common *ns)
116 return container_of(ns, struct uts_namespace, ns);
119 static struct ns_common *utsns_get(struct task_struct *task)
121 struct uts_namespace *ns = NULL;
122 struct nsproxy *nsproxy;
125 nsproxy = task->nsproxy;
127 ns = nsproxy->uts_ns;
132 return ns ? &ns->ns : NULL;
135 static void utsns_put(struct ns_common *ns)
137 put_uts_ns(to_uts_ns(ns));
140 static int utsns_install(struct nsset *nsset, struct ns_common *new)
142 struct nsproxy *nsproxy = nsset->nsproxy;
143 struct uts_namespace *ns = to_uts_ns(new);
145 if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN) ||
146 !ns_capable(nsset->cred->user_ns, CAP_SYS_ADMIN))
150 put_uts_ns(nsproxy->uts_ns);
151 nsproxy->uts_ns = ns;
155 static struct user_namespace *utsns_owner(struct ns_common *ns)
157 return to_uts_ns(ns)->user_ns;
160 const struct proc_ns_operations utsns_operations = {
162 .type = CLONE_NEWUTS,
165 .install = utsns_install,
166 .owner = utsns_owner,
169 void __init uts_ns_init(void)
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),