xref: /openbmc/linux/net/sched/cls_cgroup.c (revision 8a8e04df4747661daaee77e98e102d99c9e09b98) 
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 	.subsys_id	= net_cls_subsys_id,
81 	.base_cftypes	= ss_files,
82 	.module		= THIS_MODULE,
83 };
84 
85 struct cls_cgroup_head {
86 	u32			handle;
87 	struct tcf_exts		exts;
88 	struct tcf_ematch_tree	ematches;
89 };
90 
91 static int cls_cgroup_classify(struct sk_buff *skb, const struct tcf_proto *tp,
92 			       struct tcf_result *res)
93 {
94 	struct cls_cgroup_head *head = tp->root;
95 	u32 classid;
96 
97 	rcu_read_lock();
98 	classid = task_cls_state(current)->classid;
99 	rcu_read_unlock();
100 
101 	/*
102 	 * Due to the nature of the classifier it is required to ignore all
103 	 * packets originating from softirq context as accessing `current'
104 	 * would lead to false results.
105 	 *
106 	 * This test assumes that all callers of dev_queue_xmit() explicitely
107 	 * disable bh. Knowing this, it is possible to detect softirq based
108 	 * calls by looking at the number of nested bh disable calls because
109 	 * softirqs always disables bh.
110 	 */
111 	if (in_serving_softirq()) {
112 		/* If there is an sk_classid we'll use that. */
113 		if (!skb->sk)
114 			return -1;
115 		classid = skb->sk->sk_classid;
116 	}
117 
118 	if (!classid)
119 		return -1;
120 
121 	if (!tcf_em_tree_match(skb, &head->ematches, NULL))
122 		return -1;
123 
124 	res->classid = classid;
125 	res->class = 0;
126 	return tcf_exts_exec(skb, &head->exts, res);
127 }
128 
129 static unsigned long cls_cgroup_get(struct tcf_proto *tp, u32 handle)
130 {
131 	return 0UL;
132 }
133 
134 static void cls_cgroup_put(struct tcf_proto *tp, unsigned long f)
135 {
136 }
137 
138 static int cls_cgroup_init(struct tcf_proto *tp)
139 {
140 	return 0;
141 }
142 
143 static const struct tcf_ext_map cgroup_ext_map = {
144 	.action = TCA_CGROUP_ACT,
145 	.police = TCA_CGROUP_POLICE,
146 };
147 
148 static const struct nla_policy cgroup_policy[TCA_CGROUP_MAX + 1] = {
149 	[TCA_CGROUP_EMATCHES]	= { .type = NLA_NESTED },
150 };
151 
152 static int cls_cgroup_change(struct tcf_proto *tp, unsigned long base,
153 			     u32 handle, struct nlattr **tca,
154 			     unsigned long *arg)
155 {
156 	struct nlattr *tb[TCA_CGROUP_MAX + 1];
157 	struct cls_cgroup_head *head = tp->root;
158 	struct tcf_ematch_tree t;
159 	struct tcf_exts e;
160 	int err;
161 
162 	if (!tca[TCA_OPTIONS])
163 		return -EINVAL;
164 
165 	if (head == NULL) {
166 		if (!handle)
167 			return -EINVAL;
168 
169 		head = kzalloc(sizeof(*head), GFP_KERNEL);
170 		if (head == NULL)
171 			return -ENOBUFS;
172 
173 		head->handle = handle;
174 
175 		tcf_tree_lock(tp);
176 		tp->root = head;
177 		tcf_tree_unlock(tp);
178 	}
179 
180 	if (handle != head->handle)
181 		return -ENOENT;
182 
183 	err = nla_parse_nested(tb, TCA_CGROUP_MAX, tca[TCA_OPTIONS],
184 			       cgroup_policy);
185 	if (err < 0)
186 		return err;
187 
188 	err = tcf_exts_validate(tp, tb, tca[TCA_RATE], &e, &cgroup_ext_map);
189 	if (err < 0)
190 		return err;
191 
192 	err = tcf_em_tree_validate(tp, tb[TCA_CGROUP_EMATCHES], &t);
193 	if (err < 0)
194 		return err;
195 
196 	tcf_exts_change(tp, &head->exts, &e);
197 	tcf_em_tree_change(tp, &head->ematches, &t);
198 
199 	return 0;
200 }
201 
202 static void cls_cgroup_destroy(struct tcf_proto *tp)
203 {
204 	struct cls_cgroup_head *head = tp->root;
205 
206 	if (head) {
207 		tcf_exts_destroy(tp, &head->exts);
208 		tcf_em_tree_destroy(tp, &head->ematches);
209 		kfree(head);
210 	}
211 }
212 
213 static int cls_cgroup_delete(struct tcf_proto *tp, unsigned long arg)
214 {
215 	return -EOPNOTSUPP;
216 }
217 
218 static void cls_cgroup_walk(struct tcf_proto *tp, struct tcf_walker *arg)
219 {
220 	struct cls_cgroup_head *head = tp->root;
221 
222 	if (arg->count < arg->skip)
223 		goto skip;
224 
225 	if (arg->fn(tp, (unsigned long) head, arg) < 0) {
226 		arg->stop = 1;
227 		return;
228 	}
229 skip:
230 	arg->count++;
231 }
232 
233 static int cls_cgroup_dump(struct tcf_proto *tp, unsigned long fh,
234 			   struct sk_buff *skb, struct tcmsg *t)
235 {
236 	struct cls_cgroup_head *head = tp->root;
237 	unsigned char *b = skb_tail_pointer(skb);
238 	struct nlattr *nest;
239 
240 	t->tcm_handle = head->handle;
241 
242 	nest = nla_nest_start(skb, TCA_OPTIONS);
243 	if (nest == NULL)
244 		goto nla_put_failure;
245 
246 	if (tcf_exts_dump(skb, &head->exts, &cgroup_ext_map) < 0 ||
247 	    tcf_em_tree_dump(skb, &head->ematches, TCA_CGROUP_EMATCHES) < 0)
248 		goto nla_put_failure;
249 
250 	nla_nest_end(skb, nest);
251 
252 	if (tcf_exts_dump_stats(skb, &head->exts, &cgroup_ext_map) < 0)
253 		goto nla_put_failure;
254 
255 	return skb->len;
256 
257 nla_put_failure:
258 	nlmsg_trim(skb, b);
259 	return -1;
260 }
261 
262 static struct tcf_proto_ops cls_cgroup_ops __read_mostly = {
263 	.kind		=	"cgroup",
264 	.init		=	cls_cgroup_init,
265 	.change		=	cls_cgroup_change,
266 	.classify	=	cls_cgroup_classify,
267 	.destroy	=	cls_cgroup_destroy,
268 	.get		=	cls_cgroup_get,
269 	.put		=	cls_cgroup_put,
270 	.delete		=	cls_cgroup_delete,
271 	.walk		=	cls_cgroup_walk,
272 	.dump		=	cls_cgroup_dump,
273 	.owner		=	THIS_MODULE,
274 };
275 
276 static int __init init_cgroup_cls(void)
277 {
278 	int ret;
279 
280 	ret = cgroup_load_subsys(&net_cls_subsys);
281 	if (ret)
282 		goto out;
283 
284 	ret = register_tcf_proto_ops(&cls_cgroup_ops);
285 	if (ret)
286 		cgroup_unload_subsys(&net_cls_subsys);
287 
288 out:
289 	return ret;
290 }
291 
292 static void __exit exit_cgroup_cls(void)
293 {
294 	unregister_tcf_proto_ops(&cls_cgroup_ops);
295 
296 	cgroup_unload_subsys(&net_cls_subsys);
297 }
298 
299 module_init(init_cgroup_cls);
300 module_exit(exit_cgroup_cls);
301 MODULE_LICENSE("GPL");
302