xref: /openbmc/linux/net/sched/cls_cgroup.c (revision 2d6bed9c) 
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 	 * While net_cls cgroup has the rudimentary hierarchy support of
86 	 * inheriting the parent's classid on cgroup creation, it doesn't
87 	 * properly propagates config changes in ancestors to their
88 	 * descendents.  A child should follow the parent's configuration
89 	 * but be allowed to override it.  Fix it and remove the following.
90 	 */
91 	.broken_hierarchy = true,
92 };
93 
94 struct cls_cgroup_head {
95 	u32			handle;
96 	struct tcf_exts		exts;
97 	struct tcf_ematch_tree	ematches;
98 };
99 
100 static int cls_cgroup_classify(struct sk_buff *skb, const struct tcf_proto *tp,
101 			       struct tcf_result *res)
102 {
103 	struct cls_cgroup_head *head = tp->root;
104 	u32 classid;
105 
106 	rcu_read_lock();
107 	classid = task_cls_state(current)->classid;
108 	rcu_read_unlock();
109 
110 	/*
111 	 * Due to the nature of the classifier it is required to ignore all
112 	 * packets originating from softirq context as accessing `current'
113 	 * would lead to false results.
114 	 *
115 	 * This test assumes that all callers of dev_queue_xmit() explicitely
116 	 * disable bh. Knowing this, it is possible to detect softirq based
117 	 * calls by looking at the number of nested bh disable calls because
118 	 * softirqs always disables bh.
119 	 */
120 	if (in_serving_softirq()) {
121 		/* If there is an sk_classid we'll use that. */
122 		if (!skb->sk)
123 			return -1;
124 		classid = skb->sk->sk_classid;
125 	}
126 
127 	if (!classid)
128 		return -1;
129 
130 	if (!tcf_em_tree_match(skb, &head->ematches, NULL))
131 		return -1;
132 
133 	res->classid = classid;
134 	res->class = 0;
135 	return tcf_exts_exec(skb, &head->exts, res);
136 }
137 
138 static unsigned long cls_cgroup_get(struct tcf_proto *tp, u32 handle)
139 {
140 	return 0UL;
141 }
142 
143 static void cls_cgroup_put(struct tcf_proto *tp, unsigned long f)
144 {
145 }
146 
147 static int cls_cgroup_init(struct tcf_proto *tp)
148 {
149 	return 0;
150 }
151 
152 static const struct tcf_ext_map cgroup_ext_map = {
153 	.action = TCA_CGROUP_ACT,
154 	.police = TCA_CGROUP_POLICE,
155 };
156 
157 static const struct nla_policy cgroup_policy[TCA_CGROUP_MAX + 1] = {
158 	[TCA_CGROUP_EMATCHES]	= { .type = NLA_NESTED },
159 };
160 
161 static int cls_cgroup_change(struct sk_buff *in_skb,
162 			     struct tcf_proto *tp, unsigned long base,
163 			     u32 handle, struct nlattr **tca,
164 			     unsigned long *arg)
165 {
166 	struct nlattr *tb[TCA_CGROUP_MAX + 1];
167 	struct cls_cgroup_head *head = tp->root;
168 	struct tcf_ematch_tree t;
169 	struct tcf_exts e;
170 	int err;
171 
172 	if (!tca[TCA_OPTIONS])
173 		return -EINVAL;
174 
175 	if (head == NULL) {
176 		if (!handle)
177 			return -EINVAL;
178 
179 		head = kzalloc(sizeof(*head), GFP_KERNEL);
180 		if (head == NULL)
181 			return -ENOBUFS;
182 
183 		head->handle = handle;
184 
185 		tcf_tree_lock(tp);
186 		tp->root = head;
187 		tcf_tree_unlock(tp);
188 	}
189 
190 	if (handle != head->handle)
191 		return -ENOENT;
192 
193 	err = nla_parse_nested(tb, TCA_CGROUP_MAX, tca[TCA_OPTIONS],
194 			       cgroup_policy);
195 	if (err < 0)
196 		return err;
197 
198 	err = tcf_exts_validate(tp, tb, tca[TCA_RATE], &e, &cgroup_ext_map);
199 	if (err < 0)
200 		return err;
201 
202 	err = tcf_em_tree_validate(tp, tb[TCA_CGROUP_EMATCHES], &t);
203 	if (err < 0)
204 		return err;
205 
206 	tcf_exts_change(tp, &head->exts, &e);
207 	tcf_em_tree_change(tp, &head->ematches, &t);
208 
209 	return 0;
210 }
211 
212 static void cls_cgroup_destroy(struct tcf_proto *tp)
213 {
214 	struct cls_cgroup_head *head = tp->root;
215 
216 	if (head) {
217 		tcf_exts_destroy(tp, &head->exts);
218 		tcf_em_tree_destroy(tp, &head->ematches);
219 		kfree(head);
220 	}
221 }
222 
223 static int cls_cgroup_delete(struct tcf_proto *tp, unsigned long arg)
224 {
225 	return -EOPNOTSUPP;
226 }
227 
228 static void cls_cgroup_walk(struct tcf_proto *tp, struct tcf_walker *arg)
229 {
230 	struct cls_cgroup_head *head = tp->root;
231 
232 	if (arg->count < arg->skip)
233 		goto skip;
234 
235 	if (arg->fn(tp, (unsigned long) head, arg) < 0) {
236 		arg->stop = 1;
237 		return;
238 	}
239 skip:
240 	arg->count++;
241 }
242 
243 static int cls_cgroup_dump(struct tcf_proto *tp, unsigned long fh,
244 			   struct sk_buff *skb, struct tcmsg *t)
245 {
246 	struct cls_cgroup_head *head = tp->root;
247 	unsigned char *b = skb_tail_pointer(skb);
248 	struct nlattr *nest;
249 
250 	t->tcm_handle = head->handle;
251 
252 	nest = nla_nest_start(skb, TCA_OPTIONS);
253 	if (nest == NULL)
254 		goto nla_put_failure;
255 
256 	if (tcf_exts_dump(skb, &head->exts, &cgroup_ext_map) < 0 ||
257 	    tcf_em_tree_dump(skb, &head->ematches, TCA_CGROUP_EMATCHES) < 0)
258 		goto nla_put_failure;
259 
260 	nla_nest_end(skb, nest);
261 
262 	if (tcf_exts_dump_stats(skb, &head->exts, &cgroup_ext_map) < 0)
263 		goto nla_put_failure;
264 
265 	return skb->len;
266 
267 nla_put_failure:
268 	nlmsg_trim(skb, b);
269 	return -1;
270 }
271 
272 static struct tcf_proto_ops cls_cgroup_ops __read_mostly = {
273 	.kind		=	"cgroup",
274 	.init		=	cls_cgroup_init,
275 	.change		=	cls_cgroup_change,
276 	.classify	=	cls_cgroup_classify,
277 	.destroy	=	cls_cgroup_destroy,
278 	.get		=	cls_cgroup_get,
279 	.put		=	cls_cgroup_put,
280 	.delete		=	cls_cgroup_delete,
281 	.walk		=	cls_cgroup_walk,
282 	.dump		=	cls_cgroup_dump,
283 	.owner		=	THIS_MODULE,
284 };
285 
286 static int __init init_cgroup_cls(void)
287 {
288 	int ret;
289 
290 	ret = cgroup_load_subsys(&net_cls_subsys);
291 	if (ret)
292 		goto out;
293 
294 	ret = register_tcf_proto_ops(&cls_cgroup_ops);
295 	if (ret)
296 		cgroup_unload_subsys(&net_cls_subsys);
297 
298 out:
299 	return ret;
300 }
301 
302 static void __exit exit_cgroup_cls(void)
303 {
304 	unregister_tcf_proto_ops(&cls_cgroup_ops);
305 
306 	cgroup_unload_subsys(&net_cls_subsys);
307 }
308 
309 module_init(init_cgroup_cls);
310 module_exit(exit_cgroup_cls);
311 MODULE_LICENSE("GPL");
312