f84fdc3a7f279219d8bf3e8e97683562d748f711
[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 struct cgroup_subsys_state *cgrp_create(struct cgroup_subsys *ss,
26                                                struct cgroup *cgrp);
27 static void cgrp_destroy(struct cgroup_subsys *ss, struct cgroup *cgrp);
28 static int cgrp_populate(struct cgroup_subsys *ss, struct cgroup *cgrp);
29
30 struct cgroup_subsys net_cls_subsys = {
31         .name           = "net_cls",
32         .create         = cgrp_create,
33         .destroy        = cgrp_destroy,
34         .populate       = cgrp_populate,
35 #ifdef CONFIG_NET_CLS_CGROUP
36         .subsys_id      = net_cls_subsys_id,
37 #endif
38         .module         = THIS_MODULE,
39 };
40
41
42 static inline struct cgroup_cls_state *cgrp_cls_state(struct cgroup *cgrp)
43 {
44         return container_of(cgroup_subsys_state(cgrp, net_cls_subsys_id),
45                             struct cgroup_cls_state, css);
46 }
47
48 static inline struct cgroup_cls_state *task_cls_state(struct task_struct *p)
49 {
50         return container_of(task_subsys_state(p, net_cls_subsys_id),
51                             struct cgroup_cls_state, css);
52 }
53
54 static struct cgroup_subsys_state *cgrp_create(struct cgroup_subsys *ss,
55                                                  struct cgroup *cgrp)
56 {
57         struct cgroup_cls_state *cs;
58
59         cs = kzalloc(sizeof(*cs), GFP_KERNEL);
60         if (!cs)
61                 return ERR_PTR(-ENOMEM);
62
63         if (cgrp->parent)
64                 cs->classid = cgrp_cls_state(cgrp->parent)->classid;
65
66         return &cs->css;
67 }
68
69 static void cgrp_destroy(struct cgroup_subsys *ss, struct cgroup *cgrp)
70 {
71         kfree(cgrp_cls_state(cgrp));
72 }
73
74 static u64 read_classid(struct cgroup *cgrp, struct cftype *cft)
75 {
76         return cgrp_cls_state(cgrp)->classid;
77 }
78
79 static int write_classid(struct cgroup *cgrp, struct cftype *cft, u64 value)
80 {
81         cgrp_cls_state(cgrp)->classid = (u32) value;
82         return 0;
83 }
84
85 static struct cftype ss_files[] = {
86         {
87                 .name = "classid",
88                 .read_u64 = read_classid,
89                 .write_u64 = write_classid,
90         },
91 };
92
93 static int cgrp_populate(struct cgroup_subsys *ss, struct cgroup *cgrp)
94 {
95         return cgroup_add_files(cgrp, ss, ss_files, ARRAY_SIZE(ss_files));
96 }
97
98 struct cls_cgroup_head {
99         u32                     handle;
100         struct tcf_exts         exts;
101         struct tcf_ematch_tree  ematches;
102 };
103
104 static int cls_cgroup_classify(struct sk_buff *skb, const struct tcf_proto *tp,
105                                struct tcf_result *res)
106 {
107         struct cls_cgroup_head *head = tp->root;
108         u32 classid;
109
110         rcu_read_lock();
111         classid = task_cls_state(current)->classid;
112         rcu_read_unlock();
113
114         /*
115          * Due to the nature of the classifier it is required to ignore all
116          * packets originating from softirq context as accessing `current'
117          * would lead to false results.
118          *
119          * This test assumes that all callers of dev_queue_xmit() explicitely
120          * disable bh. Knowing this, it is possible to detect softirq based
121          * calls by looking at the number of nested bh disable calls because
122          * softirqs always disables bh.
123          */
124         if (in_serving_softirq()) {
125                 /* If there is an sk_classid we'll use that. */
126                 if (!skb->sk)
127                         return -1;
128                 classid = skb->sk->sk_classid;
129         }
130
131         if (!classid)
132                 return -1;
133
134         if (!tcf_em_tree_match(skb, &head->ematches, NULL))
135                 return -1;
136
137         res->classid = classid;
138         res->class = 0;
139         return tcf_exts_exec(skb, &head->exts, res);
140 }
141
142 static unsigned long cls_cgroup_get(struct tcf_proto *tp, u32 handle)
143 {
144         return 0UL;
145 }
146
147 static void cls_cgroup_put(struct tcf_proto *tp, unsigned long f)
148 {
149 }
150
151 static int cls_cgroup_init(struct tcf_proto *tp)
152 {
153         return 0;
154 }
155
156 static const struct tcf_ext_map cgroup_ext_map = {
157         .action = TCA_CGROUP_ACT,
158         .police = TCA_CGROUP_POLICE,
159 };
160
161 static const struct nla_policy cgroup_policy[TCA_CGROUP_MAX + 1] = {
162         [TCA_CGROUP_EMATCHES]   = { .type = NLA_NESTED },
163 };
164
165 static int cls_cgroup_change(struct tcf_proto *tp, unsigned long base,
166                              u32 handle, struct nlattr **tca,
167                              unsigned long *arg)
168 {
169         struct nlattr *tb[TCA_CGROUP_MAX + 1];
170         struct cls_cgroup_head *head = tp->root;
171         struct tcf_ematch_tree t;
172         struct tcf_exts e;
173         int err;
174
175         if (!tca[TCA_OPTIONS])
176                 return -EINVAL;
177
178         if (head == NULL) {
179                 if (!handle)
180                         return -EINVAL;
181
182                 head = kzalloc(sizeof(*head), GFP_KERNEL);
183                 if (head == NULL)
184                         return -ENOBUFS;
185
186                 head->handle = handle;
187
188                 tcf_tree_lock(tp);
189                 tp->root = head;
190                 tcf_tree_unlock(tp);
191         }
192
193         if (handle != head->handle)
194                 return -ENOENT;
195
196         err = nla_parse_nested(tb, TCA_CGROUP_MAX, tca[TCA_OPTIONS],
197                                cgroup_policy);
198         if (err < 0)
199                 return err;
200
201         err = tcf_exts_validate(tp, tb, tca[TCA_RATE], &e, &cgroup_ext_map);
202         if (err < 0)
203                 return err;
204
205         err = tcf_em_tree_validate(tp, tb[TCA_CGROUP_EMATCHES], &t);
206         if (err < 0)
207                 return err;
208
209         tcf_exts_change(tp, &head->exts, &e);
210         tcf_em_tree_change(tp, &head->ematches, &t);
211
212         return 0;
213 }
214
215 static void cls_cgroup_destroy(struct tcf_proto *tp)
216 {
217         struct cls_cgroup_head *head = tp->root;
218
219         if (head) {
220                 tcf_exts_destroy(tp, &head->exts);
221                 tcf_em_tree_destroy(tp, &head->ematches);
222                 kfree(head);
223         }
224 }
225
226 static int cls_cgroup_delete(struct tcf_proto *tp, unsigned long arg)
227 {
228         return -EOPNOTSUPP;
229 }
230
231 static void cls_cgroup_walk(struct tcf_proto *tp, struct tcf_walker *arg)
232 {
233         struct cls_cgroup_head *head = tp->root;
234
235         if (arg->count < arg->skip)
236                 goto skip;
237
238         if (arg->fn(tp, (unsigned long) head, arg) < 0) {
239                 arg->stop = 1;
240                 return;
241         }
242 skip:
243         arg->count++;
244 }
245
246 static int cls_cgroup_dump(struct tcf_proto *tp, unsigned long fh,
247                            struct sk_buff *skb, struct tcmsg *t)
248 {
249         struct cls_cgroup_head *head = tp->root;
250         unsigned char *b = skb_tail_pointer(skb);
251         struct nlattr *nest;
252
253         t->tcm_handle = head->handle;
254
255         nest = nla_nest_start(skb, TCA_OPTIONS);
256         if (nest == NULL)
257                 goto nla_put_failure;
258
259         if (tcf_exts_dump(skb, &head->exts, &cgroup_ext_map) < 0 ||
260             tcf_em_tree_dump(skb, &head->ematches, TCA_CGROUP_EMATCHES) < 0)
261                 goto nla_put_failure;
262
263         nla_nest_end(skb, nest);
264
265         if (tcf_exts_dump_stats(skb, &head->exts, &cgroup_ext_map) < 0)
266                 goto nla_put_failure;
267
268         return skb->len;
269
270 nla_put_failure:
271         nlmsg_trim(skb, b);
272         return -1;
273 }
274
275 static struct tcf_proto_ops cls_cgroup_ops __read_mostly = {
276         .kind           =       "cgroup",
277         .init           =       cls_cgroup_init,
278         .change         =       cls_cgroup_change,
279         .classify       =       cls_cgroup_classify,
280         .destroy        =       cls_cgroup_destroy,
281         .get            =       cls_cgroup_get,
282         .put            =       cls_cgroup_put,
283         .delete         =       cls_cgroup_delete,
284         .walk           =       cls_cgroup_walk,
285         .dump           =       cls_cgroup_dump,
286         .owner          =       THIS_MODULE,
287 };
288
289 static int __init init_cgroup_cls(void)
290 {
291         int ret;
292
293         ret = cgroup_load_subsys(&net_cls_subsys);
294         if (ret)
295                 goto out;
296
297 #ifndef CONFIG_NET_CLS_CGROUP
298         /* We can't use rcu_assign_pointer because this is an int. */
299         smp_wmb();
300         net_cls_subsys_id = net_cls_subsys.subsys_id;
301 #endif
302
303         ret = register_tcf_proto_ops(&cls_cgroup_ops);
304         if (ret)
305                 cgroup_unload_subsys(&net_cls_subsys);
306
307 out:
308         return ret;
309 }
310
311 static void __exit exit_cgroup_cls(void)
312 {
313         unregister_tcf_proto_ops(&cls_cgroup_ops);
314
315 #ifndef CONFIG_NET_CLS_CGROUP
316         net_cls_subsys_id = -1;
317         synchronize_rcu();
318 #endif
319
320         cgroup_unload_subsys(&net_cls_subsys);
321 }
322
323 module_init(init_cgroup_cls);
324 module_exit(exit_cgroup_cls);
325 MODULE_LICENSE("GPL");