blob: 6976cd47dcf6028270eee444228eca7a340ca2d2
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 | |
20 | static struct ucounts *inc_uts_namespaces(struct user_namespace *ns) |
21 | { |
22 | return inc_ucount(ns, current_euid(), UCOUNT_UTS_NAMESPACES); |
23 | } |
24 | |
25 | static void dec_uts_namespaces(struct ucounts *ucounts) |
26 | { |
27 | dec_ucount(ucounts, UCOUNT_UTS_NAMESPACES); |
28 | } |
29 | |
30 | static struct uts_namespace *create_uts_ns(void) |
31 | { |
32 | struct uts_namespace *uts_ns; |
33 | |
34 | uts_ns = kmalloc(sizeof(struct uts_namespace), 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 kmalloc), new ns otherwise |
44 | */ |
45 | static 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 | |
75 | fail_free: |
76 | kfree(ns); |
77 | fail_dec: |
78 | dec_uts_namespaces(ucounts); |
79 | fail: |
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 | */ |
89 | struct 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 | |
106 | void 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 | kfree(ns); |
115 | } |
116 | |
117 | static inline struct uts_namespace *to_uts_ns(struct ns_common *ns) |
118 | { |
119 | return container_of(ns, struct uts_namespace, ns); |
120 | } |
121 | |
122 | static 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 | |
138 | static void utsns_put(struct ns_common *ns) |
139 | { |
140 | put_uts_ns(to_uts_ns(ns)); |
141 | } |
142 | |
143 | static 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 | |
157 | static struct user_namespace *utsns_owner(struct ns_common *ns) |
158 | { |
159 | return to_uts_ns(ns)->user_ns; |
160 | } |
161 | |
162 | const 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 |