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
create_uts_ns(void)20 static 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 */
clone_uts_ns(struct user_namespace * user_ns,struct uts_namespace * old_ns)35 static 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 */
copy_utsname(unsigned long flags,struct user_namespace * user_ns,struct uts_namespace * old_ns)64 struct 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
free_uts_ns(struct kref * kref)81 void 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
utsns_get(struct task_struct * task)91 static 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
utsns_put(void * ns)107 static void utsns_put(void *ns)
108 {
109 put_uts_ns(ns);
110 }
111
utsns_install(struct nsproxy * nsproxy,void * new)112 static 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 !nsown_capable(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
utsns_inum(void * vp)126 static unsigned int utsns_inum(void *vp)
127 {
128 struct uts_namespace *ns = vp;
129
130 return ns->proc_inum;
131 }
132
133 const 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 };
141