1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
|
#include "cgroup-internal.h"
#include <linux/sched/task.h>
#include <linux/slab.h>
#include <linux/nsproxy.h>
#include <linux/proc_ns.h>
/* cgroup namespaces */
static struct ucounts *inc_cgroup_namespaces(struct user_namespace *ns)
{
return inc_ucount(ns, current_euid(), UCOUNT_CGROUP_NAMESPACES);
}
static void dec_cgroup_namespaces(struct ucounts *ucounts)
{
dec_ucount(ucounts, UCOUNT_CGROUP_NAMESPACES);
}
static struct cgroup_namespace *alloc_cgroup_ns(void)
{
struct cgroup_namespace *new_ns;
int ret;
new_ns = kzalloc(sizeof(struct cgroup_namespace), GFP_KERNEL);
if (!new_ns)
return ERR_PTR(-ENOMEM);
ret = ns_alloc_inum(&new_ns->ns);
if (ret) {
kfree(new_ns);
return ERR_PTR(ret);
}
atomic_set(&new_ns->count, 1);
new_ns->ns.ops = &cgroupns_operations;
return new_ns;
}
void free_cgroup_ns(struct cgroup_namespace *ns)
{
put_css_set(ns->root_cset);
dec_cgroup_namespaces(ns->ucounts);
put_user_ns(ns->user_ns);
ns_free_inum(&ns->ns);
kfree(ns);
}
EXPORT_SYMBOL(free_cgroup_ns);
struct cgroup_namespace *copy_cgroup_ns(unsigned long flags,
struct user_namespace *user_ns,
struct cgroup_namespace *old_ns)
{
struct cgroup_namespace *new_ns;
struct ucounts *ucounts;
struct css_set *cset;
BUG_ON(!old_ns);
if (!(flags & CLONE_NEWCGROUP)) {
get_cgroup_ns(old_ns);
return old_ns;
}
/* Allow only sysadmin to create cgroup namespace. */
if (!ns_capable(user_ns, CAP_SYS_ADMIN))
return ERR_PTR(-EPERM);
ucounts = inc_cgroup_namespaces(user_ns);
if (!ucounts)
return ERR_PTR(-ENOSPC);
/* It is not safe to take cgroup_mutex here */
spin_lock_irq(&css_set_lock);
cset = task_css_set(current);
get_css_set(cset);
spin_unlock_irq(&css_set_lock);
new_ns = alloc_cgroup_ns();
if (IS_ERR(new_ns)) {
put_css_set(cset);
dec_cgroup_namespaces(ucounts);
return new_ns;
}
new_ns->user_ns = get_user_ns(user_ns);
new_ns->ucounts = ucounts;
new_ns->root_cset = cset;
return new_ns;
}
static inline struct cgroup_namespace *to_cg_ns(struct ns_common *ns)
{
return container_of(ns, struct cgroup_namespace, ns);
}
static int cgroupns_install(struct nsproxy *nsproxy, struct ns_common *ns)
{
struct cgroup_namespace *cgroup_ns = to_cg_ns(ns);
if (!ns_capable(current_user_ns(), CAP_SYS_ADMIN) ||
!ns_capable(cgroup_ns->user_ns, CAP_SYS_ADMIN))
return -EPERM;
/* Don't need to do anything if we are attaching to our own cgroupns. */
if (cgroup_ns == nsproxy->cgroup_ns)
return 0;
get_cgroup_ns(cgroup_ns);
put_cgroup_ns(nsproxy->cgroup_ns);
nsproxy->cgroup_ns = cgroup_ns;
return 0;
}
static struct ns_common *cgroupns_get(struct task_struct *task)
{
struct cgroup_namespace *ns = NULL;
struct nsproxy *nsproxy;
task_lock(task);
nsproxy = task->nsproxy;
if (nsproxy) {
ns = nsproxy->cgroup_ns;
get_cgroup_ns(ns);
}
task_unlock(task);
return ns ? &ns->ns : NULL;
}
static void cgroupns_put(struct ns_common *ns)
{
put_cgroup_ns(to_cg_ns(ns));
}
static struct user_namespace *cgroupns_owner(struct ns_common *ns)
{
return to_cg_ns(ns)->user_ns;
}
const struct proc_ns_operations cgroupns_operations = {
.name = "cgroup",
.type = CLONE_NEWCGROUP,
.get = cgroupns_get,
.put = cgroupns_put,
.install = cgroupns_install,
.owner = cgroupns_owner,
};
static __init int cgroup_namespaces_init(void)
{
return 0;
}
subsys_initcall(cgroup_namespaces_init);
|
