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dcfe149b TH |
1 | #include "cgroup-internal.h" |
2 | ||
3 | #include <linux/sched.h> | |
4 | #include <linux/slab.h> | |
5 | #include <linux/nsproxy.h> | |
6 | #include <linux/proc_ns.h> | |
7 | ||
8 | ||
9 | /* cgroup namespaces */ | |
10 | ||
11 | static struct ucounts *inc_cgroup_namespaces(struct user_namespace *ns) | |
12 | { | |
13 | return inc_ucount(ns, current_euid(), UCOUNT_CGROUP_NAMESPACES); | |
14 | } | |
15 | ||
16 | static void dec_cgroup_namespaces(struct ucounts *ucounts) | |
17 | { | |
18 | dec_ucount(ucounts, UCOUNT_CGROUP_NAMESPACES); | |
19 | } | |
20 | ||
21 | static struct cgroup_namespace *alloc_cgroup_ns(void) | |
22 | { | |
23 | struct cgroup_namespace *new_ns; | |
24 | int ret; | |
25 | ||
26 | new_ns = kzalloc(sizeof(struct cgroup_namespace), GFP_KERNEL); | |
27 | if (!new_ns) | |
28 | return ERR_PTR(-ENOMEM); | |
29 | ret = ns_alloc_inum(&new_ns->ns); | |
30 | if (ret) { | |
31 | kfree(new_ns); | |
32 | return ERR_PTR(ret); | |
33 | } | |
34 | atomic_set(&new_ns->count, 1); | |
35 | new_ns->ns.ops = &cgroupns_operations; | |
36 | return new_ns; | |
37 | } | |
38 | ||
39 | void free_cgroup_ns(struct cgroup_namespace *ns) | |
40 | { | |
41 | put_css_set(ns->root_cset); | |
42 | dec_cgroup_namespaces(ns->ucounts); | |
43 | put_user_ns(ns->user_ns); | |
44 | ns_free_inum(&ns->ns); | |
45 | kfree(ns); | |
46 | } | |
47 | EXPORT_SYMBOL(free_cgroup_ns); | |
48 | ||
49 | struct cgroup_namespace *copy_cgroup_ns(unsigned long flags, | |
50 | struct user_namespace *user_ns, | |
51 | struct cgroup_namespace *old_ns) | |
52 | { | |
53 | struct cgroup_namespace *new_ns; | |
54 | struct ucounts *ucounts; | |
55 | struct css_set *cset; | |
56 | ||
57 | BUG_ON(!old_ns); | |
58 | ||
59 | if (!(flags & CLONE_NEWCGROUP)) { | |
60 | get_cgroup_ns(old_ns); | |
61 | return old_ns; | |
62 | } | |
63 | ||
64 | /* Allow only sysadmin to create cgroup namespace. */ | |
65 | if (!ns_capable(user_ns, CAP_SYS_ADMIN)) | |
66 | return ERR_PTR(-EPERM); | |
67 | ||
68 | ucounts = inc_cgroup_namespaces(user_ns); | |
69 | if (!ucounts) | |
70 | return ERR_PTR(-ENOSPC); | |
71 | ||
72 | /* It is not safe to take cgroup_mutex here */ | |
73 | spin_lock_irq(&css_set_lock); | |
74 | cset = task_css_set(current); | |
75 | get_css_set(cset); | |
76 | spin_unlock_irq(&css_set_lock); | |
77 | ||
78 | new_ns = alloc_cgroup_ns(); | |
79 | if (IS_ERR(new_ns)) { | |
80 | put_css_set(cset); | |
81 | dec_cgroup_namespaces(ucounts); | |
82 | return new_ns; | |
83 | } | |
84 | ||
85 | new_ns->user_ns = get_user_ns(user_ns); | |
86 | new_ns->ucounts = ucounts; | |
87 | new_ns->root_cset = cset; | |
88 | ||
89 | return new_ns; | |
90 | } | |
91 | ||
92 | static inline struct cgroup_namespace *to_cg_ns(struct ns_common *ns) | |
93 | { | |
94 | return container_of(ns, struct cgroup_namespace, ns); | |
95 | } | |
96 | ||
97 | static int cgroupns_install(struct nsproxy *nsproxy, struct ns_common *ns) | |
98 | { | |
99 | struct cgroup_namespace *cgroup_ns = to_cg_ns(ns); | |
100 | ||
101 | if (!ns_capable(current_user_ns(), CAP_SYS_ADMIN) || | |
102 | !ns_capable(cgroup_ns->user_ns, CAP_SYS_ADMIN)) | |
103 | return -EPERM; | |
104 | ||
105 | /* Don't need to do anything if we are attaching to our own cgroupns. */ | |
106 | if (cgroup_ns == nsproxy->cgroup_ns) | |
107 | return 0; | |
108 | ||
109 | get_cgroup_ns(cgroup_ns); | |
110 | put_cgroup_ns(nsproxy->cgroup_ns); | |
111 | nsproxy->cgroup_ns = cgroup_ns; | |
112 | ||
113 | return 0; | |
114 | } | |
115 | ||
116 | static struct ns_common *cgroupns_get(struct task_struct *task) | |
117 | { | |
118 | struct cgroup_namespace *ns = NULL; | |
119 | struct nsproxy *nsproxy; | |
120 | ||
121 | task_lock(task); | |
122 | nsproxy = task->nsproxy; | |
123 | if (nsproxy) { | |
124 | ns = nsproxy->cgroup_ns; | |
125 | get_cgroup_ns(ns); | |
126 | } | |
127 | task_unlock(task); | |
128 | ||
129 | return ns ? &ns->ns : NULL; | |
130 | } | |
131 | ||
132 | static void cgroupns_put(struct ns_common *ns) | |
133 | { | |
134 | put_cgroup_ns(to_cg_ns(ns)); | |
135 | } | |
136 | ||
137 | static struct user_namespace *cgroupns_owner(struct ns_common *ns) | |
138 | { | |
139 | return to_cg_ns(ns)->user_ns; | |
140 | } | |
141 | ||
142 | const struct proc_ns_operations cgroupns_operations = { | |
143 | .name = "cgroup", | |
144 | .type = CLONE_NEWCGROUP, | |
145 | .get = cgroupns_get, | |
146 | .put = cgroupns_put, | |
147 | .install = cgroupns_install, | |
148 | .owner = cgroupns_owner, | |
149 | }; | |
150 | ||
151 | static __init int cgroup_namespaces_init(void) | |
152 | { | |
153 | return 0; | |
154 | } | |
155 | subsys_initcall(cgroup_namespaces_init); |