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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
32
33
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
60
61
62
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 !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
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};
141