xref: /openbmc/linux/net/sched/cls_cgroup.c (revision 78c99ba1) 
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/types.h>
14 #include <linux/string.h>
15 #include <linux/errno.h>
16 #include <linux/skbuff.h>
17 #include <linux/cgroup.h>
18 #include <net/rtnetlink.h>
19 #include <net/pkt_cls.h>
20 
21 struct cgroup_cls_state
22 {
23 	struct cgroup_subsys_state css;
24 	u32 classid;
25 };
26 
27 static inline struct cgroup_cls_state *cgrp_cls_state(struct cgroup *cgrp)
28 {
29 	return container_of(cgroup_subsys_state(cgrp, net_cls_subsys_id),
30 			    struct cgroup_cls_state, css);
31 }
32 
33 static inline struct cgroup_cls_state *task_cls_state(struct task_struct *p)
34 {
35 	return container_of(task_subsys_state(p, net_cls_subsys_id),
36 			    struct cgroup_cls_state, css);
37 }
38 
39 static struct cgroup_subsys_state *cgrp_create(struct cgroup_subsys *ss,
40 						 struct cgroup *cgrp)
41 {
42 	struct cgroup_cls_state *cs;
43 
44 	if (!(cs = kzalloc(sizeof(*cs), GFP_KERNEL)))
45 		return ERR_PTR(-ENOMEM);
46 
47 	if (cgrp->parent)
48 		cs->classid = cgrp_cls_state(cgrp->parent)->classid;
49 
50 	return &cs->css;
51 }
52 
53 static void cgrp_destroy(struct cgroup_subsys *ss, struct cgroup *cgrp)
54 {
55 	kfree(cgrp_cls_state(cgrp));
56 }
57 
58 static u64 read_classid(struct cgroup *cgrp, struct cftype *cft)
59 {
60 	return cgrp_cls_state(cgrp)->classid;
61 }
62 
63 static int write_classid(struct cgroup *cgrp, struct cftype *cft, u64 value)
64 {
65 	if (!cgroup_lock_live_group(cgrp))
66 		return -ENODEV;
67 
68 	cgrp_cls_state(cgrp)->classid = (u32) value;
69 
70 	cgroup_unlock();
71 
72 	return 0;
73 }
74 
75 static struct cftype ss_files[] = {
76 	{
77 		.name = "classid",
78 		.read_u64 = read_classid,
79 		.write_u64 = write_classid,
80 	},
81 };
82 
83 static int cgrp_populate(struct cgroup_subsys *ss, struct cgroup *cgrp)
84 {
85 	return cgroup_add_files(cgrp, ss, ss_files, ARRAY_SIZE(ss_files));
86 }
87 
88 struct cgroup_subsys net_cls_subsys = {
89 	.name		= "net_cls",
90 	.create		= cgrp_create,
91 	.destroy	= cgrp_destroy,
92 	.populate	= cgrp_populate,
93 	.subsys_id	= net_cls_subsys_id,
94 };
95 
96 struct cls_cgroup_head
97 {
98 	u32			handle;
99 	struct tcf_exts		exts;
100 	struct tcf_ematch_tree	ematches;
101 };
102 
103 static int cls_cgroup_classify(struct sk_buff *skb, struct tcf_proto *tp,
104 			       struct tcf_result *res)
105 {
106 	struct cls_cgroup_head *head = tp->root;
107 	u32 classid;
108 
109 	/*
110 	 * Due to the nature of the classifier it is required to ignore all
111 	 * packets originating from softirq context as accessing `current'
112 	 * would lead to false results.
113 	 *
114 	 * This test assumes that all callers of dev_queue_xmit() explicitely
115 	 * disable bh. Knowing this, it is possible to detect softirq based
116 	 * calls by looking at the number of nested bh disable calls because
117 	 * softirqs always disables bh.
118 	 */
119 	if (softirq_count() != SOFTIRQ_OFFSET)
120 		return -1;
121 
122 	rcu_read_lock();
123 	classid = task_cls_state(current)->classid;
124 	rcu_read_unlock();
125 
126 	if (!classid)
127 		return -1;
128 
129 	if (!tcf_em_tree_match(skb, &head->ematches, NULL))
130 		return -1;
131 
132 	res->classid = classid;
133 	res->class = 0;
134 	return tcf_exts_exec(skb, &head->exts, res);
135 }
136 
137 static unsigned long cls_cgroup_get(struct tcf_proto *tp, u32 handle)
138 {
139 	return 0UL;
140 }
141 
142 static void cls_cgroup_put(struct tcf_proto *tp, unsigned long f)
143 {
144 }
145 
146 static int cls_cgroup_init(struct tcf_proto *tp)
147 {
148 	return 0;
149 }
150 
151 static const struct tcf_ext_map cgroup_ext_map = {
152 	.action = TCA_CGROUP_ACT,
153 	.police = TCA_CGROUP_POLICE,
154 };
155 
156 static const struct nla_policy cgroup_policy[TCA_CGROUP_MAX + 1] = {
157 	[TCA_CGROUP_EMATCHES]	= { .type = NLA_NESTED },
158 };
159 
160 static int cls_cgroup_change(struct tcf_proto *tp, unsigned long base,
161 			     u32 handle, struct nlattr **tca,
162 			     unsigned long *arg)
163 {
164 	struct nlattr *tb[TCA_CGROUP_MAX+1];
165 	struct cls_cgroup_head *head = tp->root;
166 	struct tcf_ematch_tree t;
167 	struct tcf_exts e;
168 	int err;
169 
170 	if (!tca[TCA_OPTIONS])
171 		return -EINVAL;
172 
173 	if (head == NULL) {
174 		if (!handle)
175 			return -EINVAL;
176 
177 		head = kzalloc(sizeof(*head), GFP_KERNEL);
178 		if (head == NULL)
179 			return -ENOBUFS;
180 
181 		head->handle = handle;
182 
183 		tcf_tree_lock(tp);
184 		tp->root = head;
185 		tcf_tree_unlock(tp);
186 	}
187 
188 	if (handle != head->handle)
189 		return -ENOENT;
190 
191 	err = nla_parse_nested(tb, TCA_CGROUP_MAX, tca[TCA_OPTIONS],
192 			       cgroup_policy);
193 	if (err < 0)
194 		return err;
195 
196 	err = tcf_exts_validate(tp, tb, tca[TCA_RATE], &e, &cgroup_ext_map);
197 	if (err < 0)
198 		return err;
199 
200 	err = tcf_em_tree_validate(tp, tb[TCA_CGROUP_EMATCHES], &t);
201 	if (err < 0)
202 		return err;
203 
204 	tcf_exts_change(tp, &head->exts, &e);
205 	tcf_em_tree_change(tp, &head->ematches, &t);
206 
207 	return 0;
208 }
209 
210 static void cls_cgroup_destroy(struct tcf_proto *tp)
211 {
212 	struct cls_cgroup_head *head = tp->root;
213 
214 	if (head) {
215 		tcf_exts_destroy(tp, &head->exts);
216 		tcf_em_tree_destroy(tp, &head->ematches);
217 		kfree(head);
218 	}
219 }
220 
221 static int cls_cgroup_delete(struct tcf_proto *tp, unsigned long arg)
222 {
223 	return -EOPNOTSUPP;
224 }
225 
226 static void cls_cgroup_walk(struct tcf_proto *tp, struct tcf_walker *arg)
227 {
228 	struct cls_cgroup_head *head = tp->root;
229 
230 	if (arg->count < arg->skip)
231 		goto skip;
232 
233 	if (arg->fn(tp, (unsigned long) head, arg) < 0) {
234 		arg->stop = 1;
235 		return;
236 	}
237 skip:
238 	arg->count++;
239 }
240 
241 static int cls_cgroup_dump(struct tcf_proto *tp, unsigned long fh,
242 			   struct sk_buff *skb, struct tcmsg *t)
243 {
244 	struct cls_cgroup_head *head = tp->root;
245 	unsigned char *b = skb_tail_pointer(skb);
246 	struct nlattr *nest;
247 
248 	t->tcm_handle = head->handle;
249 
250 	nest = nla_nest_start(skb, TCA_OPTIONS);
251 	if (nest == NULL)
252 		goto nla_put_failure;
253 
254 	if (tcf_exts_dump(skb, &head->exts, &cgroup_ext_map) < 0 ||
255 	    tcf_em_tree_dump(skb, &head->ematches, TCA_CGROUP_EMATCHES) < 0)
256 		goto nla_put_failure;
257 
258 	nla_nest_end(skb, nest);
259 
260 	if (tcf_exts_dump_stats(skb, &head->exts, &cgroup_ext_map) < 0)
261 		goto nla_put_failure;
262 
263 	return skb->len;
264 
265 nla_put_failure:
266 	nlmsg_trim(skb, b);
267 	return -1;
268 }
269 
270 static struct tcf_proto_ops cls_cgroup_ops __read_mostly = {
271 	.kind		=	"cgroup",
272 	.init		=	cls_cgroup_init,
273 	.change		=	cls_cgroup_change,
274 	.classify	=	cls_cgroup_classify,
275 	.destroy	=	cls_cgroup_destroy,
276 	.get		=	cls_cgroup_get,
277 	.put		=	cls_cgroup_put,
278 	.delete		=	cls_cgroup_delete,
279 	.walk		=	cls_cgroup_walk,
280 	.dump		=	cls_cgroup_dump,
281 	.owner		=	THIS_MODULE,
282 };
283 
284 static int __init init_cgroup_cls(void)
285 {
286 	return register_tcf_proto_ops(&cls_cgroup_ops);
287 }
288 
289 static void __exit exit_cgroup_cls(void)
290 {
291 	unregister_tcf_proto_ops(&cls_cgroup_ops);
292 }
293 
294 module_init(init_cgroup_cls);
295 module_exit(exit_cgroup_cls);
296 MODULE_LICENSE("GPL");
297