cls_cgroup.c revision c1b52739e45f5969b208ebc377f52468280af11e 
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 <linux/fdtable.h>
21#include <net/rtnetlink.h>
22#include <net/pkt_cls.h>
23#include <net/sock.h>
24#include <net/cls_cgroup.h>
25
26static inline struct cgroup_cls_state *cgrp_cls_state(struct cgroup *cgrp)
27{
28	return container_of(cgroup_subsys_state(cgrp, net_cls_subsys_id),
29			    struct cgroup_cls_state, css);
30}
31
32static inline struct cgroup_cls_state *task_cls_state(struct task_struct *p)
33{
34	return container_of(task_subsys_state(p, net_cls_subsys_id),
35			    struct cgroup_cls_state, css);
36}
37
38static struct cgroup_subsys_state *cgrp_css_alloc(struct cgroup *cgrp)
39{
40	struct cgroup_cls_state *cs;
41
42	cs = kzalloc(sizeof(*cs), GFP_KERNEL);
43	if (!cs)
44		return ERR_PTR(-ENOMEM);
45	return &cs->css;
46}
47
48static int cgrp_css_online(struct cgroup *cgrp)
49{
50	if (cgrp->parent)
51		cgrp_cls_state(cgrp)->classid =
52			cgrp_cls_state(cgrp->parent)->classid;
53	return 0;
54}
55
56static void cgrp_css_free(struct cgroup *cgrp)
57{
58	kfree(cgrp_cls_state(cgrp));
59}
60
61static int update_classid(const void *v, struct file *file, unsigned n)
62{
63	int err;
64	struct socket *sock = sock_from_file(file, &err);
65	if (sock)
66		sock->sk->sk_classid = (u32)(unsigned long)v;
67	return 0;
68}
69
70static void cgrp_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
71{
72	struct task_struct *p;
73	void *v;
74
75	cgroup_taskset_for_each(p, cgrp, tset) {
76		task_lock(p);
77		v = (void *)(unsigned long)task_cls_classid(p);
78		iterate_fd(p->files, 0, update_classid, v);
79		task_unlock(p);
80	}
81}
82
83static u64 read_classid(struct cgroup *cgrp, struct cftype *cft)
84{
85	return cgrp_cls_state(cgrp)->classid;
86}
87
88static int write_classid(struct cgroup *cgrp, struct cftype *cft, u64 value)
89{
90	cgrp_cls_state(cgrp)->classid = (u32) value;
91	return 0;
92}
93
94static struct cftype ss_files[] = {
95	{
96		.name = "classid",
97		.read_u64 = read_classid,
98		.write_u64 = write_classid,
99	},
100	{ }	/* terminate */
101};
102
103struct cgroup_subsys net_cls_subsys = {
104	.name		= "net_cls",
105	.css_alloc	= cgrp_css_alloc,
106	.css_online	= cgrp_css_online,
107	.css_free	= cgrp_css_free,
108	.attach		= cgrp_attach,
109	.subsys_id	= net_cls_subsys_id,
110	.base_cftypes	= ss_files,
111	.module		= THIS_MODULE,
112};
113
114struct cls_cgroup_head {
115	u32			handle;
116	struct tcf_exts		exts;
117	struct tcf_ematch_tree	ematches;
118};
119
120static int cls_cgroup_classify(struct sk_buff *skb, const struct tcf_proto *tp,
121			       struct tcf_result *res)
122{
123	struct cls_cgroup_head *head = tp->root;
124	u32 classid;
125
126	rcu_read_lock();
127	classid = task_cls_state(current)->classid;
128	rcu_read_unlock();
129
130	/*
131	 * Due to the nature of the classifier it is required to ignore all
132	 * packets originating from softirq context as accessing `current'
133	 * would lead to false results.
134	 *
135	 * This test assumes that all callers of dev_queue_xmit() explicitely
136	 * disable bh. Knowing this, it is possible to detect softirq based
137	 * calls by looking at the number of nested bh disable calls because
138	 * softirqs always disables bh.
139	 */
140	if (in_serving_softirq()) {
141		/* If there is an sk_classid we'll use that. */
142		if (!skb->sk)
143			return -1;
144		classid = skb->sk->sk_classid;
145	}
146
147	if (!classid)
148		return -1;
149
150	if (!tcf_em_tree_match(skb, &head->ematches, NULL))
151		return -1;
152
153	res->classid = classid;
154	res->class = 0;
155	return tcf_exts_exec(skb, &head->exts, res);
156}
157
158static unsigned long cls_cgroup_get(struct tcf_proto *tp, u32 handle)
159{
160	return 0UL;
161}
162
163static void cls_cgroup_put(struct tcf_proto *tp, unsigned long f)
164{
165}
166
167static int cls_cgroup_init(struct tcf_proto *tp)
168{
169	return 0;
170}
171
172static const struct tcf_ext_map cgroup_ext_map = {
173	.action = TCA_CGROUP_ACT,
174	.police = TCA_CGROUP_POLICE,
175};
176
177static const struct nla_policy cgroup_policy[TCA_CGROUP_MAX + 1] = {
178	[TCA_CGROUP_EMATCHES]	= { .type = NLA_NESTED },
179};
180
181static int cls_cgroup_change(struct net *net, struct sk_buff *in_skb,
182			     struct tcf_proto *tp, unsigned long base,
183			     u32 handle, struct nlattr **tca,
184			     unsigned long *arg)
185{
186	struct nlattr *tb[TCA_CGROUP_MAX + 1];
187	struct cls_cgroup_head *head = tp->root;
188	struct tcf_ematch_tree t;
189	struct tcf_exts e;
190	int err;
191
192	if (!tca[TCA_OPTIONS])
193		return -EINVAL;
194
195	if (head == NULL) {
196		if (!handle)
197			return -EINVAL;
198
199		head = kzalloc(sizeof(*head), GFP_KERNEL);
200		if (head == NULL)
201			return -ENOBUFS;
202
203		head->handle = handle;
204
205		tcf_tree_lock(tp);
206		tp->root = head;
207		tcf_tree_unlock(tp);
208	}
209
210	if (handle != head->handle)
211		return -ENOENT;
212
213	err = nla_parse_nested(tb, TCA_CGROUP_MAX, tca[TCA_OPTIONS],
214			       cgroup_policy);
215	if (err < 0)
216		return err;
217
218	err = tcf_exts_validate(net, tp, tb, tca[TCA_RATE], &e,
219				&cgroup_ext_map);
220	if (err < 0)
221		return err;
222
223	err = tcf_em_tree_validate(tp, tb[TCA_CGROUP_EMATCHES], &t);
224	if (err < 0)
225		return err;
226
227	tcf_exts_change(tp, &head->exts, &e);
228	tcf_em_tree_change(tp, &head->ematches, &t);
229
230	return 0;
231}
232
233static void cls_cgroup_destroy(struct tcf_proto *tp)
234{
235	struct cls_cgroup_head *head = tp->root;
236
237	if (head) {
238		tcf_exts_destroy(tp, &head->exts);
239		tcf_em_tree_destroy(tp, &head->ematches);
240		kfree(head);
241	}
242}
243
244static int cls_cgroup_delete(struct tcf_proto *tp, unsigned long arg)
245{
246	return -EOPNOTSUPP;
247}
248
249static void cls_cgroup_walk(struct tcf_proto *tp, struct tcf_walker *arg)
250{
251	struct cls_cgroup_head *head = tp->root;
252
253	if (arg->count < arg->skip)
254		goto skip;
255
256	if (arg->fn(tp, (unsigned long) head, arg) < 0) {
257		arg->stop = 1;
258		return;
259	}
260skip:
261	arg->count++;
262}
263
264static int cls_cgroup_dump(struct tcf_proto *tp, unsigned long fh,
265			   struct sk_buff *skb, struct tcmsg *t)
266{
267	struct cls_cgroup_head *head = tp->root;
268	unsigned char *b = skb_tail_pointer(skb);
269	struct nlattr *nest;
270
271	t->tcm_handle = head->handle;
272
273	nest = nla_nest_start(skb, TCA_OPTIONS);
274	if (nest == NULL)
275		goto nla_put_failure;
276
277	if (tcf_exts_dump(skb, &head->exts, &cgroup_ext_map) < 0 ||
278	    tcf_em_tree_dump(skb, &head->ematches, TCA_CGROUP_EMATCHES) < 0)
279		goto nla_put_failure;
280
281	nla_nest_end(skb, nest);
282
283	if (tcf_exts_dump_stats(skb, &head->exts, &cgroup_ext_map) < 0)
284		goto nla_put_failure;
285
286	return skb->len;
287
288nla_put_failure:
289	nlmsg_trim(skb, b);
290	return -1;
291}
292
293static struct tcf_proto_ops cls_cgroup_ops __read_mostly = {
294	.kind		=	"cgroup",
295	.init		=	cls_cgroup_init,
296	.change		=	cls_cgroup_change,
297	.classify	=	cls_cgroup_classify,
298	.destroy	=	cls_cgroup_destroy,
299	.get		=	cls_cgroup_get,
300	.put		=	cls_cgroup_put,
301	.delete		=	cls_cgroup_delete,
302	.walk		=	cls_cgroup_walk,
303	.dump		=	cls_cgroup_dump,
304	.owner		=	THIS_MODULE,
305};
306
307static int __init init_cgroup_cls(void)
308{
309	int ret;
310
311	ret = cgroup_load_subsys(&net_cls_subsys);
312	if (ret)
313		goto out;
314
315	ret = register_tcf_proto_ops(&cls_cgroup_ops);
316	if (ret)
317		cgroup_unload_subsys(&net_cls_subsys);
318
319out:
320	return ret;
321}
322
323static void __exit exit_cgroup_cls(void)
324{
325	unregister_tcf_proto_ops(&cls_cgroup_ops);
326
327	cgroup_unload_subsys(&net_cls_subsys);
328}
329
330module_init(init_cgroup_cls);
331module_exit(exit_cgroup_cls);
332MODULE_LICENSE("GPL");
333