cgroup: mark subsystems with broken hierarchy support and whine if cgroups are nested...
[linux-3.10.git] / net / sched / cls_cgroup.c
1 /*
2  * net/sched/cls_cgroup.c       Control Group Classifier
3  *
4  *              This program is free software; you can redistribute it and/or
5  *              modify it under the terms of the GNU General Public License
6  *              as published by the Free Software Foundation; either version
7  *              2 of the License, or (at your option) any later version.
8  *
9  * Authors:     Thomas Graf <tgraf@suug.ch>
10  */
11
12 #include <linux/module.h>
13 #include <linux/slab.h>
14 #include <linux/types.h>
15 #include <linux/string.h>
16 #include <linux/errno.h>
17 #include <linux/skbuff.h>
18 #include <linux/cgroup.h>
19 #include <linux/rcupdate.h>
20 #include <net/rtnetlink.h>
21 #include <net/pkt_cls.h>
22 #include <net/sock.h>
23 #include <net/cls_cgroup.h>
24
25 static inline struct cgroup_cls_state *cgrp_cls_state(struct cgroup *cgrp)
26 {
27         return container_of(cgroup_subsys_state(cgrp, net_cls_subsys_id),
28                             struct cgroup_cls_state, css);
29 }
30
31 static inline struct cgroup_cls_state *task_cls_state(struct task_struct *p)
32 {
33         return container_of(task_subsys_state(p, net_cls_subsys_id),
34                             struct cgroup_cls_state, css);
35 }
36
37 static struct cgroup_subsys_state *cgrp_create(struct cgroup *cgrp)
38 {
39         struct cgroup_cls_state *cs;
40
41         cs = kzalloc(sizeof(*cs), GFP_KERNEL);
42         if (!cs)
43                 return ERR_PTR(-ENOMEM);
44
45         if (cgrp->parent)
46                 cs->classid = cgrp_cls_state(cgrp->parent)->classid;
47
48         return &cs->css;
49 }
50
51 static void cgrp_destroy(struct cgroup *cgrp)
52 {
53         kfree(cgrp_cls_state(cgrp));
54 }
55
56 static u64 read_classid(struct cgroup *cgrp, struct cftype *cft)
57 {
58         return cgrp_cls_state(cgrp)->classid;
59 }
60
61 static int write_classid(struct cgroup *cgrp, struct cftype *cft, u64 value)
62 {
63         cgrp_cls_state(cgrp)->classid = (u32) value;
64         return 0;
65 }
66
67 static struct cftype ss_files[] = {
68         {
69                 .name = "classid",
70                 .read_u64 = read_classid,
71                 .write_u64 = write_classid,
72         },
73         { }     /* terminate */
74 };
75
76 struct cgroup_subsys net_cls_subsys = {
77         .name           = "net_cls",
78         .create         = cgrp_create,
79         .destroy        = cgrp_destroy,
80 #ifdef CONFIG_NET_CLS_CGROUP
81         .subsys_id      = net_cls_subsys_id,
82 #endif
83         .base_cftypes   = ss_files,
84         .module         = THIS_MODULE,
85
86         /*
87          * While net_cls cgroup has the rudimentary hierarchy support of
88          * inheriting the parent's classid on cgroup creation, it doesn't
89          * properly propagates config changes in ancestors to their
90          * descendents.  A child should follow the parent's configuration
91          * but be allowed to override it.  Fix it and remove the following.
92          */
93         .broken_hierarchy = true,
94 };
95
96 struct cls_cgroup_head {
97         u32                     handle;
98         struct tcf_exts         exts;
99         struct tcf_ematch_tree  ematches;
100 };
101
102 static int cls_cgroup_classify(struct sk_buff *skb, const struct tcf_proto *tp,
103                                struct tcf_result *res)
104 {
105         struct cls_cgroup_head *head = tp->root;
106         u32 classid;
107
108         rcu_read_lock();
109         classid = task_cls_state(current)->classid;
110         rcu_read_unlock();
111
112         /*
113          * Due to the nature of the classifier it is required to ignore all
114          * packets originating from softirq context as accessing `current'
115          * would lead to false results.
116          *
117          * This test assumes that all callers of dev_queue_xmit() explicitely
118          * disable bh. Knowing this, it is possible to detect softirq based
119          * calls by looking at the number of nested bh disable calls because
120          * softirqs always disables bh.
121          */
122         if (in_serving_softirq()) {
123                 /* If there is an sk_classid we'll use that. */
124                 if (!skb->sk)
125                         return -1;
126                 classid = skb->sk->sk_classid;
127         }
128
129         if (!classid)
130                 return -1;
131
132         if (!tcf_em_tree_match(skb, &head->ematches, NULL))
133                 return -1;
134
135         res->classid = classid;
136         res->class = 0;
137         return tcf_exts_exec(skb, &head->exts, res);
138 }
139
140 static unsigned long cls_cgroup_get(struct tcf_proto *tp, u32 handle)
141 {
142         return 0UL;
143 }
144
145 static void cls_cgroup_put(struct tcf_proto *tp, unsigned long f)
146 {
147 }
148
149 static int cls_cgroup_init(struct tcf_proto *tp)
150 {
151         return 0;
152 }
153
154 static const struct tcf_ext_map cgroup_ext_map = {
155         .action = TCA_CGROUP_ACT,
156         .police = TCA_CGROUP_POLICE,
157 };
158
159 static const struct nla_policy cgroup_policy[TCA_CGROUP_MAX + 1] = {
160         [TCA_CGROUP_EMATCHES]   = { .type = NLA_NESTED },
161 };
162
163 static int cls_cgroup_change(struct tcf_proto *tp, unsigned long base,
164                              u32 handle, struct nlattr **tca,
165                              unsigned long *arg)
166 {
167         struct nlattr *tb[TCA_CGROUP_MAX + 1];
168         struct cls_cgroup_head *head = tp->root;
169         struct tcf_ematch_tree t;
170         struct tcf_exts e;
171         int err;
172
173         if (!tca[TCA_OPTIONS])
174                 return -EINVAL;
175
176         if (head == NULL) {
177                 if (!handle)
178                         return -EINVAL;
179
180                 head = kzalloc(sizeof(*head), GFP_KERNEL);
181                 if (head == NULL)
182                         return -ENOBUFS;
183
184                 head->handle = handle;
185
186                 tcf_tree_lock(tp);
187                 tp->root = head;
188                 tcf_tree_unlock(tp);
189         }
190
191         if (handle != head->handle)
192                 return -ENOENT;
193
194         err = nla_parse_nested(tb, TCA_CGROUP_MAX, tca[TCA_OPTIONS],
195                                cgroup_policy);
196         if (err < 0)
197                 return err;
198
199         err = tcf_exts_validate(tp, tb, tca[TCA_RATE], &e, &cgroup_ext_map);
200         if (err < 0)
201                 return err;
202
203         err = tcf_em_tree_validate(tp, tb[TCA_CGROUP_EMATCHES], &t);
204         if (err < 0)
205                 return err;
206
207         tcf_exts_change(tp, &head->exts, &e);
208         tcf_em_tree_change(tp, &head->ematches, &t);
209
210         return 0;
211 }
212
213 static void cls_cgroup_destroy(struct tcf_proto *tp)
214 {
215         struct cls_cgroup_head *head = tp->root;
216
217         if (head) {
218                 tcf_exts_destroy(tp, &head->exts);
219                 tcf_em_tree_destroy(tp, &head->ematches);
220                 kfree(head);
221         }
222 }
223
224 static int cls_cgroup_delete(struct tcf_proto *tp, unsigned long arg)
225 {
226         return -EOPNOTSUPP;
227 }
228
229 static void cls_cgroup_walk(struct tcf_proto *tp, struct tcf_walker *arg)
230 {
231         struct cls_cgroup_head *head = tp->root;
232
233         if (arg->count < arg->skip)
234                 goto skip;
235
236         if (arg->fn(tp, (unsigned long) head, arg) < 0) {
237                 arg->stop = 1;
238                 return;
239         }
240 skip:
241         arg->count++;
242 }
243
244 static int cls_cgroup_dump(struct tcf_proto *tp, unsigned long fh,
245                            struct sk_buff *skb, struct tcmsg *t)
246 {
247         struct cls_cgroup_head *head = tp->root;
248         unsigned char *b = skb_tail_pointer(skb);
249         struct nlattr *nest;
250
251         t->tcm_handle = head->handle;
252
253         nest = nla_nest_start(skb, TCA_OPTIONS);
254         if (nest == NULL)
255                 goto nla_put_failure;
256
257         if (tcf_exts_dump(skb, &head->exts, &cgroup_ext_map) < 0 ||
258             tcf_em_tree_dump(skb, &head->ematches, TCA_CGROUP_EMATCHES) < 0)
259                 goto nla_put_failure;
260
261         nla_nest_end(skb, nest);
262
263         if (tcf_exts_dump_stats(skb, &head->exts, &cgroup_ext_map) < 0)
264                 goto nla_put_failure;
265
266         return skb->len;
267
268 nla_put_failure:
269         nlmsg_trim(skb, b);
270         return -1;
271 }
272
273 static struct tcf_proto_ops cls_cgroup_ops __read_mostly = {
274         .kind           =       "cgroup",
275         .init           =       cls_cgroup_init,
276         .change         =       cls_cgroup_change,
277         .classify       =       cls_cgroup_classify,
278         .destroy        =       cls_cgroup_destroy,
279         .get            =       cls_cgroup_get,
280         .put            =       cls_cgroup_put,
281         .delete         =       cls_cgroup_delete,
282         .walk           =       cls_cgroup_walk,
283         .dump           =       cls_cgroup_dump,
284         .owner          =       THIS_MODULE,
285 };
286
287 static int __init init_cgroup_cls(void)
288 {
289         int ret;
290
291         ret = cgroup_load_subsys(&net_cls_subsys);
292         if (ret)
293                 goto out;
294
295 #ifndef CONFIG_NET_CLS_CGROUP
296         /* We can't use rcu_assign_pointer because this is an int. */
297         smp_wmb();
298         net_cls_subsys_id = net_cls_subsys.subsys_id;
299 #endif
300
301         ret = register_tcf_proto_ops(&cls_cgroup_ops);
302         if (ret)
303                 cgroup_unload_subsys(&net_cls_subsys);
304
305 out:
306         return ret;
307 }
308
309 static void __exit exit_cgroup_cls(void)
310 {
311         unregister_tcf_proto_ops(&cls_cgroup_ops);
312
313 #ifndef CONFIG_NET_CLS_CGROUP
314         net_cls_subsys_id = -1;
315         synchronize_rcu();
316 #endif
317
318         cgroup_unload_subsys(&net_cls_subsys);
319 }
320
321 module_init(init_cgroup_cls);
322 module_exit(exit_cgroup_cls);
323 MODULE_LICENSE("GPL");