xref: /linux/net/sched/cls_cgroup.c (revision d39d0ed196aa1685bb24771e92f78633c66ac9cb)
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 #else
38 #define net_cls_subsys_id net_cls_subsys.subsys_id
39 #endif
40 	.module		= THIS_MODULE,
41 };
42 
43 
44 static inline struct cgroup_cls_state *cgrp_cls_state(struct cgroup *cgrp)
45 {
46 	return container_of(cgroup_subsys_state(cgrp, net_cls_subsys_id),
47 			    struct cgroup_cls_state, css);
48 }
49 
50 static inline struct cgroup_cls_state *task_cls_state(struct task_struct *p)
51 {
52 	return container_of(task_subsys_state(p, net_cls_subsys_id),
53 			    struct cgroup_cls_state, css);
54 }
55 
56 static struct cgroup_subsys_state *cgrp_create(struct cgroup_subsys *ss,
57 						 struct cgroup *cgrp)
58 {
59 	struct cgroup_cls_state *cs;
60 
61 	if (!(cs = kzalloc(sizeof(*cs), GFP_KERNEL)))
62 		return ERR_PTR(-ENOMEM);
63 
64 	if (cgrp->parent)
65 		cs->classid = cgrp_cls_state(cgrp->parent)->classid;
66 
67 	return &cs->css;
68 }
69 
70 static void cgrp_destroy(struct cgroup_subsys *ss, struct cgroup *cgrp)
71 {
72 	kfree(cgrp_cls_state(cgrp));
73 }
74 
75 static u64 read_classid(struct cgroup *cgrp, struct cftype *cft)
76 {
77 	return cgrp_cls_state(cgrp)->classid;
78 }
79 
80 static int write_classid(struct cgroup *cgrp, struct cftype *cft, u64 value)
81 {
82 	cgrp_cls_state(cgrp)->classid = (u32) value;
83 	return 0;
84 }
85 
86 static struct cftype ss_files[] = {
87 	{
88 		.name = "classid",
89 		.read_u64 = read_classid,
90 		.write_u64 = write_classid,
91 	},
92 };
93 
94 static int cgrp_populate(struct cgroup_subsys *ss, struct cgroup *cgrp)
95 {
96 	return cgroup_add_files(cgrp, ss, ss_files, ARRAY_SIZE(ss_files));
97 }
98 
99 struct cls_cgroup_head
100 {
101 	u32			handle;
102 	struct tcf_exts		exts;
103 	struct tcf_ematch_tree	ematches;
104 };
105 
106 static int cls_cgroup_classify(struct sk_buff *skb, struct tcf_proto *tp,
107 			       struct tcf_result *res)
108 {
109 	struct cls_cgroup_head *head = tp->root;
110 	u32 classid;
111 
112 	rcu_read_lock();
113 	classid = task_cls_state(current)->classid;
114 	rcu_read_unlock();
115 
116 	/*
117 	 * Due to the nature of the classifier it is required to ignore all
118 	 * packets originating from softirq context as accessing `current'
119 	 * would lead to false results.
120 	 *
121 	 * This test assumes that all callers of dev_queue_xmit() explicitely
122 	 * disable bh. Knowing this, it is possible to detect softirq based
123 	 * calls by looking at the number of nested bh disable calls because
124 	 * softirqs always disables bh.
125 	 */
126 	if (softirq_count() != SOFTIRQ_OFFSET) {
127 		/* If there is an sk_classid we'll use that. */
128 		if (!skb->sk)
129 			return -1;
130 		classid = skb->sk->sk_classid;
131 	}
132 
133 	if (!classid)
134 		return -1;
135 
136 	if (!tcf_em_tree_match(skb, &head->ematches, NULL))
137 		return -1;
138 
139 	res->classid = classid;
140 	res->class = 0;
141 	return tcf_exts_exec(skb, &head->exts, res);
142 }
143 
144 static unsigned long cls_cgroup_get(struct tcf_proto *tp, u32 handle)
145 {
146 	return 0UL;
147 }
148 
149 static void cls_cgroup_put(struct tcf_proto *tp, unsigned long f)
150 {
151 }
152 
153 static int cls_cgroup_init(struct tcf_proto *tp)
154 {
155 	return 0;
156 }
157 
158 static const struct tcf_ext_map cgroup_ext_map = {
159 	.action = TCA_CGROUP_ACT,
160 	.police = TCA_CGROUP_POLICE,
161 };
162 
163 static const struct nla_policy cgroup_policy[TCA_CGROUP_MAX + 1] = {
164 	[TCA_CGROUP_EMATCHES]	= { .type = NLA_NESTED },
165 };
166 
167 static int cls_cgroup_change(struct tcf_proto *tp, unsigned long base,
168 			     u32 handle, struct nlattr **tca,
169 			     unsigned long *arg)
170 {
171 	struct nlattr *tb[TCA_CGROUP_MAX+1];
172 	struct cls_cgroup_head *head = tp->root;
173 	struct tcf_ematch_tree t;
174 	struct tcf_exts e;
175 	int err;
176 
177 	if (!tca[TCA_OPTIONS])
178 		return -EINVAL;
179 
180 	if (head == NULL) {
181 		if (!handle)
182 			return -EINVAL;
183 
184 		head = kzalloc(sizeof(*head), GFP_KERNEL);
185 		if (head == NULL)
186 			return -ENOBUFS;
187 
188 		head->handle = handle;
189 
190 		tcf_tree_lock(tp);
191 		tp->root = head;
192 		tcf_tree_unlock(tp);
193 	}
194 
195 	if (handle != head->handle)
196 		return -ENOENT;
197 
198 	err = nla_parse_nested(tb, TCA_CGROUP_MAX, tca[TCA_OPTIONS],
199 			       cgroup_policy);
200 	if (err < 0)
201 		return err;
202 
203 	err = tcf_exts_validate(tp, tb, tca[TCA_RATE], &e, &cgroup_ext_map);
204 	if (err < 0)
205 		return err;
206 
207 	err = tcf_em_tree_validate(tp, tb[TCA_CGROUP_EMATCHES], &t);
208 	if (err < 0)
209 		return err;
210 
211 	tcf_exts_change(tp, &head->exts, &e);
212 	tcf_em_tree_change(tp, &head->ematches, &t);
213 
214 	return 0;
215 }
216 
217 static void cls_cgroup_destroy(struct tcf_proto *tp)
218 {
219 	struct cls_cgroup_head *head = tp->root;
220 
221 	if (head) {
222 		tcf_exts_destroy(tp, &head->exts);
223 		tcf_em_tree_destroy(tp, &head->ematches);
224 		kfree(head);
225 	}
226 }
227 
228 static int cls_cgroup_delete(struct tcf_proto *tp, unsigned long arg)
229 {
230 	return -EOPNOTSUPP;
231 }
232 
233 static void cls_cgroup_walk(struct tcf_proto *tp, struct tcf_walker *arg)
234 {
235 	struct cls_cgroup_head *head = tp->root;
236 
237 	if (arg->count < arg->skip)
238 		goto skip;
239 
240 	if (arg->fn(tp, (unsigned long) head, arg) < 0) {
241 		arg->stop = 1;
242 		return;
243 	}
244 skip:
245 	arg->count++;
246 }
247 
248 static int cls_cgroup_dump(struct tcf_proto *tp, unsigned long fh,
249 			   struct sk_buff *skb, struct tcmsg *t)
250 {
251 	struct cls_cgroup_head *head = tp->root;
252 	unsigned char *b = skb_tail_pointer(skb);
253 	struct nlattr *nest;
254 
255 	t->tcm_handle = head->handle;
256 
257 	nest = nla_nest_start(skb, TCA_OPTIONS);
258 	if (nest == NULL)
259 		goto nla_put_failure;
260 
261 	if (tcf_exts_dump(skb, &head->exts, &cgroup_ext_map) < 0 ||
262 	    tcf_em_tree_dump(skb, &head->ematches, TCA_CGROUP_EMATCHES) < 0)
263 		goto nla_put_failure;
264 
265 	nla_nest_end(skb, nest);
266 
267 	if (tcf_exts_dump_stats(skb, &head->exts, &cgroup_ext_map) < 0)
268 		goto nla_put_failure;
269 
270 	return skb->len;
271 
272 nla_put_failure:
273 	nlmsg_trim(skb, b);
274 	return -1;
275 }
276 
277 static struct tcf_proto_ops cls_cgroup_ops __read_mostly = {
278 	.kind		=	"cgroup",
279 	.init		=	cls_cgroup_init,
280 	.change		=	cls_cgroup_change,
281 	.classify	=	cls_cgroup_classify,
282 	.destroy	=	cls_cgroup_destroy,
283 	.get		=	cls_cgroup_get,
284 	.put		=	cls_cgroup_put,
285 	.delete		=	cls_cgroup_delete,
286 	.walk		=	cls_cgroup_walk,
287 	.dump		=	cls_cgroup_dump,
288 	.owner		=	THIS_MODULE,
289 };
290 
291 static int __init init_cgroup_cls(void)
292 {
293 	int ret;
294 
295 	ret = cgroup_load_subsys(&net_cls_subsys);
296 	if (ret)
297 		goto out;
298 
299 #ifndef CONFIG_NET_CLS_CGROUP
300 	/* We can't use rcu_assign_pointer because this is an int. */
301 	smp_wmb();
302 	net_cls_subsys_id = net_cls_subsys.subsys_id;
303 #endif
304 
305 	ret = register_tcf_proto_ops(&cls_cgroup_ops);
306 	if (ret)
307 		cgroup_unload_subsys(&net_cls_subsys);
308 
309 out:
310 	return ret;
311 }
312 
313 static void __exit exit_cgroup_cls(void)
314 {
315 	unregister_tcf_proto_ops(&cls_cgroup_ops);
316 
317 #ifndef CONFIG_NET_CLS_CGROUP
318 	net_cls_subsys_id = -1;
319 	synchronize_rcu();
320 #endif
321 
322 	cgroup_unload_subsys(&net_cls_subsys);
323 }
324 
325 module_init(init_cgroup_cls);
326 module_exit(exit_cgroup_cls);
327 MODULE_LICENSE("GPL");
328