]>
Commit | Line | Data |
---|---|---|
b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
dcfe149b TH |
2 | #include "cgroup-internal.h" |
3 | ||
56cd6973 | 4 | #include <linux/sched/task.h> |
dcfe149b TH |
5 | #include <linux/slab.h> |
6 | #include <linux/nsproxy.h> | |
7 | #include <linux/proc_ns.h> | |
8 | ||
9 | ||
10 | /* cgroup namespaces */ | |
11 | ||
12 | static struct ucounts *inc_cgroup_namespaces(struct user_namespace *ns) | |
13 | { | |
14 | return inc_ucount(ns, current_euid(), UCOUNT_CGROUP_NAMESPACES); | |
15 | } | |
16 | ||
17 | static void dec_cgroup_namespaces(struct ucounts *ucounts) | |
18 | { | |
19 | dec_ucount(ucounts, UCOUNT_CGROUP_NAMESPACES); | |
20 | } | |
21 | ||
22 | static struct cgroup_namespace *alloc_cgroup_ns(void) | |
23 | { | |
24 | struct cgroup_namespace *new_ns; | |
25 | int ret; | |
26 | ||
27 | new_ns = kzalloc(sizeof(struct cgroup_namespace), GFP_KERNEL); | |
28 | if (!new_ns) | |
29 | return ERR_PTR(-ENOMEM); | |
30 | ret = ns_alloc_inum(&new_ns->ns); | |
31 | if (ret) { | |
32 | kfree(new_ns); | |
33 | return ERR_PTR(ret); | |
34 | } | |
f387882d | 35 | refcount_set(&new_ns->ns.count, 1); |
dcfe149b TH |
36 | new_ns->ns.ops = &cgroupns_operations; |
37 | return new_ns; | |
38 | } | |
39 | ||
40 | void free_cgroup_ns(struct cgroup_namespace *ns) | |
41 | { | |
42 | put_css_set(ns->root_cset); | |
43 | dec_cgroup_namespaces(ns->ucounts); | |
44 | put_user_ns(ns->user_ns); | |
45 | ns_free_inum(&ns->ns); | |
46 | kfree(ns); | |
47 | } | |
48 | EXPORT_SYMBOL(free_cgroup_ns); | |
49 | ||
50 | struct cgroup_namespace *copy_cgroup_ns(unsigned long flags, | |
51 | struct user_namespace *user_ns, | |
52 | struct cgroup_namespace *old_ns) | |
53 | { | |
54 | struct cgroup_namespace *new_ns; | |
55 | struct ucounts *ucounts; | |
56 | struct css_set *cset; | |
57 | ||
58 | BUG_ON(!old_ns); | |
59 | ||
60 | if (!(flags & CLONE_NEWCGROUP)) { | |
61 | get_cgroup_ns(old_ns); | |
62 | return old_ns; | |
63 | } | |
64 | ||
65 | /* Allow only sysadmin to create cgroup namespace. */ | |
66 | if (!ns_capable(user_ns, CAP_SYS_ADMIN)) | |
67 | return ERR_PTR(-EPERM); | |
68 | ||
69 | ucounts = inc_cgroup_namespaces(user_ns); | |
70 | if (!ucounts) | |
71 | return ERR_PTR(-ENOSPC); | |
72 | ||
73 | /* It is not safe to take cgroup_mutex here */ | |
74 | spin_lock_irq(&css_set_lock); | |
75 | cset = task_css_set(current); | |
76 | get_css_set(cset); | |
77 | spin_unlock_irq(&css_set_lock); | |
78 | ||
79 | new_ns = alloc_cgroup_ns(); | |
80 | if (IS_ERR(new_ns)) { | |
81 | put_css_set(cset); | |
82 | dec_cgroup_namespaces(ucounts); | |
83 | return new_ns; | |
84 | } | |
85 | ||
86 | new_ns->user_ns = get_user_ns(user_ns); | |
87 | new_ns->ucounts = ucounts; | |
88 | new_ns->root_cset = cset; | |
89 | ||
90 | return new_ns; | |
91 | } | |
92 | ||
93 | static inline struct cgroup_namespace *to_cg_ns(struct ns_common *ns) | |
94 | { | |
95 | return container_of(ns, struct cgroup_namespace, ns); | |
96 | } | |
97 | ||
f2a8d52e | 98 | static int cgroupns_install(struct nsset *nsset, struct ns_common *ns) |
dcfe149b | 99 | { |
f2a8d52e | 100 | struct nsproxy *nsproxy = nsset->nsproxy; |
dcfe149b TH |
101 | struct cgroup_namespace *cgroup_ns = to_cg_ns(ns); |
102 | ||
f2a8d52e | 103 | if (!ns_capable(nsset->cred->user_ns, CAP_SYS_ADMIN) || |
dcfe149b TH |
104 | !ns_capable(cgroup_ns->user_ns, CAP_SYS_ADMIN)) |
105 | return -EPERM; | |
106 | ||
107 | /* Don't need to do anything if we are attaching to our own cgroupns. */ | |
108 | if (cgroup_ns == nsproxy->cgroup_ns) | |
109 | return 0; | |
110 | ||
111 | get_cgroup_ns(cgroup_ns); | |
112 | put_cgroup_ns(nsproxy->cgroup_ns); | |
113 | nsproxy->cgroup_ns = cgroup_ns; | |
114 | ||
115 | return 0; | |
116 | } | |
117 | ||
118 | static struct ns_common *cgroupns_get(struct task_struct *task) | |
119 | { | |
120 | struct cgroup_namespace *ns = NULL; | |
121 | struct nsproxy *nsproxy; | |
122 | ||
123 | task_lock(task); | |
124 | nsproxy = task->nsproxy; | |
125 | if (nsproxy) { | |
126 | ns = nsproxy->cgroup_ns; | |
127 | get_cgroup_ns(ns); | |
128 | } | |
129 | task_unlock(task); | |
130 | ||
131 | return ns ? &ns->ns : NULL; | |
132 | } | |
133 | ||
134 | static void cgroupns_put(struct ns_common *ns) | |
135 | { | |
136 | put_cgroup_ns(to_cg_ns(ns)); | |
137 | } | |
138 | ||
139 | static struct user_namespace *cgroupns_owner(struct ns_common *ns) | |
140 | { | |
141 | return to_cg_ns(ns)->user_ns; | |
142 | } | |
143 | ||
144 | const struct proc_ns_operations cgroupns_operations = { | |
145 | .name = "cgroup", | |
146 | .type = CLONE_NEWCGROUP, | |
147 | .get = cgroupns_get, | |
148 | .put = cgroupns_put, | |
149 | .install = cgroupns_install, | |
150 | .owner = cgroupns_owner, | |
151 | }; | |
152 | ||
153 | static __init int cgroup_namespaces_init(void) | |
154 | { | |
155 | return 0; | |
156 | } | |
157 | subsys_initcall(cgroup_namespaces_init); |