cls_cgroup.c revision 6a328d8c6f03501657ad580f6f98bf9a42583ff7 
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_create(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
46	if (cgrp->parent)
47		cs->classid = cgrp_cls_state(cgrp->parent)->classid;
48
49	return &cs->css;
50}
51
52static void cgrp_destroy(struct cgroup *cgrp)
53{
54	kfree(cgrp_cls_state(cgrp));
55}
56
57static int update_classid(const void *v, struct file *file, unsigned n)
58{
59	int err;
60	struct socket *sock = sock_from_file(file, &err);
61	if (sock)
62		sock->sk->sk_classid = (u32)(unsigned long)v;
63	return 0;
64}
65
66static void cgrp_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
67{
68	struct task_struct *p;
69	void *v;
70
71	cgroup_taskset_for_each(p, cgrp, tset) {
72		task_lock(p);
73		v = (void *)(unsigned long)task_cls_classid(p);
74		iterate_fd(p->files, 0, update_classid, v);
75		task_unlock(p);
76	}
77}
78
79static u64 read_classid(struct cgroup *cgrp, struct cftype *cft)
80{
81	return cgrp_cls_state(cgrp)->classid;
82}
83
84static int write_classid(struct cgroup *cgrp, struct cftype *cft, u64 value)
85{
86	cgrp_cls_state(cgrp)->classid = (u32) value;
87	return 0;
88}
89
90static struct cftype ss_files[] = {
91	{
92		.name = "classid",
93		.read_u64 = read_classid,
94		.write_u64 = write_classid,
95	},
96	{ }	/* terminate */
97};
98
99struct cgroup_subsys net_cls_subsys = {
100	.name		= "net_cls",
101	.create		= cgrp_create,
102	.destroy	= cgrp_destroy,
103	.attach		= cgrp_attach,
104	.subsys_id	= net_cls_subsys_id,
105	.base_cftypes	= ss_files,
106	.module		= THIS_MODULE,
107
108	/*
109	 * While net_cls cgroup has the rudimentary hierarchy support of
110	 * inheriting the parent's classid on cgroup creation, it doesn't
111	 * properly propagates config changes in ancestors to their
112	 * descendents.  A child should follow the parent's configuration
113	 * but be allowed to override it.  Fix it and remove the following.
114	 */
115	.broken_hierarchy = true,
116};
117
118struct cls_cgroup_head {
119	u32			handle;
120	struct tcf_exts		exts;
121	struct tcf_ematch_tree	ematches;
122};
123
124static int cls_cgroup_classify(struct sk_buff *skb, const struct tcf_proto *tp,
125			       struct tcf_result *res)
126{
127	struct cls_cgroup_head *head = tp->root;
128	u32 classid;
129
130	rcu_read_lock();
131	classid = task_cls_state(current)->classid;
132	rcu_read_unlock();
133
134	/*
135	 * Due to the nature of the classifier it is required to ignore all
136	 * packets originating from softirq context as accessing `current'
137	 * would lead to false results.
138	 *
139	 * This test assumes that all callers of dev_queue_xmit() explicitely
140	 * disable bh. Knowing this, it is possible to detect softirq based
141	 * calls by looking at the number of nested bh disable calls because
142	 * softirqs always disables bh.
143	 */
144	if (in_serving_softirq()) {
145		/* If there is an sk_classid we'll use that. */
146		if (!skb->sk)
147			return -1;
148		classid = skb->sk->sk_classid;
149	}
150
151	if (!classid)
152		return -1;
153
154	if (!tcf_em_tree_match(skb, &head->ematches, NULL))
155		return -1;
156
157	res->classid = classid;
158	res->class = 0;
159	return tcf_exts_exec(skb, &head->exts, res);
160}
161
162static unsigned long cls_cgroup_get(struct tcf_proto *tp, u32 handle)
163{
164	return 0UL;
165}
166
167static void cls_cgroup_put(struct tcf_proto *tp, unsigned long f)
168{
169}
170
171static int cls_cgroup_init(struct tcf_proto *tp)
172{
173	return 0;
174}
175
176static const struct tcf_ext_map cgroup_ext_map = {
177	.action = TCA_CGROUP_ACT,
178	.police = TCA_CGROUP_POLICE,
179};
180
181static const struct nla_policy cgroup_policy[TCA_CGROUP_MAX + 1] = {
182	[TCA_CGROUP_EMATCHES]	= { .type = NLA_NESTED },
183};
184
185static int cls_cgroup_change(struct sk_buff *in_skb,
186			     struct tcf_proto *tp, unsigned long base,
187			     u32 handle, struct nlattr **tca,
188			     unsigned long *arg)
189{
190	struct nlattr *tb[TCA_CGROUP_MAX + 1];
191	struct cls_cgroup_head *head = tp->root;
192	struct tcf_ematch_tree t;
193	struct tcf_exts e;
194	int err;
195
196	if (!tca[TCA_OPTIONS])
197		return -EINVAL;
198
199	if (head == NULL) {
200		if (!handle)
201			return -EINVAL;
202
203		head = kzalloc(sizeof(*head), GFP_KERNEL);
204		if (head == NULL)
205			return -ENOBUFS;
206
207		head->handle = handle;
208
209		tcf_tree_lock(tp);
210		tp->root = head;
211		tcf_tree_unlock(tp);
212	}
213
214	if (handle != head->handle)
215		return -ENOENT;
216
217	err = nla_parse_nested(tb, TCA_CGROUP_MAX, tca[TCA_OPTIONS],
218			       cgroup_policy);
219	if (err < 0)
220		return err;
221
222	err = tcf_exts_validate(tp, tb, tca[TCA_RATE], &e, &cgroup_ext_map);
223	if (err < 0)
224		return err;
225
226	err = tcf_em_tree_validate(tp, tb[TCA_CGROUP_EMATCHES], &t);
227	if (err < 0)
228		return err;
229
230	tcf_exts_change(tp, &head->exts, &e);
231	tcf_em_tree_change(tp, &head->ematches, &t);
232
233	return 0;
234}
235
236static void cls_cgroup_destroy(struct tcf_proto *tp)
237{
238	struct cls_cgroup_head *head = tp->root;
239
240	if (head) {
241		tcf_exts_destroy(tp, &head->exts);
242		tcf_em_tree_destroy(tp, &head->ematches);
243		kfree(head);
244	}
245}
246
247static int cls_cgroup_delete(struct tcf_proto *tp, unsigned long arg)
248{
249	return -EOPNOTSUPP;
250}
251
252static void cls_cgroup_walk(struct tcf_proto *tp, struct tcf_walker *arg)
253{
254	struct cls_cgroup_head *head = tp->root;
255
256	if (arg->count < arg->skip)
257		goto skip;
258
259	if (arg->fn(tp, (unsigned long) head, arg) < 0) {
260		arg->stop = 1;
261		return;
262	}
263skip:
264	arg->count++;
265}
266
267static int cls_cgroup_dump(struct tcf_proto *tp, unsigned long fh,
268			   struct sk_buff *skb, struct tcmsg *t)
269{
270	struct cls_cgroup_head *head = tp->root;
271	unsigned char *b = skb_tail_pointer(skb);
272	struct nlattr *nest;
273
274	t->tcm_handle = head->handle;
275
276	nest = nla_nest_start(skb, TCA_OPTIONS);
277	if (nest == NULL)
278		goto nla_put_failure;
279
280	if (tcf_exts_dump(skb, &head->exts, &cgroup_ext_map) < 0 ||
281	    tcf_em_tree_dump(skb, &head->ematches, TCA_CGROUP_EMATCHES) < 0)
282		goto nla_put_failure;
283
284	nla_nest_end(skb, nest);
285
286	if (tcf_exts_dump_stats(skb, &head->exts, &cgroup_ext_map) < 0)
287		goto nla_put_failure;
288
289	return skb->len;
290
291nla_put_failure:
292	nlmsg_trim(skb, b);
293	return -1;
294}
295
296static struct tcf_proto_ops cls_cgroup_ops __read_mostly = {
297	.kind		=	"cgroup",
298	.init		=	cls_cgroup_init,
299	.change		=	cls_cgroup_change,
300	.classify	=	cls_cgroup_classify,
301	.destroy	=	cls_cgroup_destroy,
302	.get		=	cls_cgroup_get,
303	.put		=	cls_cgroup_put,
304	.delete		=	cls_cgroup_delete,
305	.walk		=	cls_cgroup_walk,
306	.dump		=	cls_cgroup_dump,
307	.owner		=	THIS_MODULE,
308};
309
310static int __init init_cgroup_cls(void)
311{
312	int ret;
313
314	ret = cgroup_load_subsys(&net_cls_subsys);
315	if (ret)
316		goto out;
317
318	ret = register_tcf_proto_ops(&cls_cgroup_ops);
319	if (ret)
320		cgroup_unload_subsys(&net_cls_subsys);
321
322out:
323	return ret;
324}
325
326static void __exit exit_cgroup_cls(void)
327{
328	unregister_tcf_proto_ops(&cls_cgroup_ops);
329
330	cgroup_unload_subsys(&net_cls_subsys);
331}
332
333module_init(init_cgroup_cls);
334module_exit(exit_cgroup_cls);
335MODULE_LICENSE("GPL");
336