xref: /openbmc/linux/net/sched/cls_cgroup.c (revision 3c6a73cc)
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/skbuff.h>
15 #include <linux/rcupdate.h>
16 #include <net/rtnetlink.h>
17 #include <net/pkt_cls.h>
18 #include <net/sock.h>
19 #include <net/cls_cgroup.h>
20 
21 struct cls_cgroup_head {
22 	u32			handle;
23 	struct tcf_exts		exts;
24 	struct tcf_ematch_tree	ematches;
25 	struct tcf_proto	*tp;
26 	struct rcu_head		rcu;
27 };
28 
29 static int cls_cgroup_classify(struct sk_buff *skb, const struct tcf_proto *tp,
30 			       struct tcf_result *res)
31 {
32 	struct cls_cgroup_head *head = rcu_dereference_bh(tp->root);
33 	u32 classid;
34 
35 	classid = task_cls_state(current)->classid;
36 
37 	/*
38 	 * Due to the nature of the classifier it is required to ignore all
39 	 * packets originating from softirq context as accessing `current'
40 	 * would lead to false results.
41 	 *
42 	 * This test assumes that all callers of dev_queue_xmit() explicitely
43 	 * disable bh. Knowing this, it is possible to detect softirq based
44 	 * calls by looking at the number of nested bh disable calls because
45 	 * softirqs always disables bh.
46 	 */
47 	if (in_serving_softirq()) {
48 		/* If there is an sk_classid we'll use that. */
49 		if (!skb->sk)
50 			return -1;
51 		classid = skb->sk->sk_classid;
52 	}
53 
54 	if (!classid)
55 		return -1;
56 
57 	if (!tcf_em_tree_match(skb, &head->ematches, NULL))
58 		return -1;
59 
60 	res->classid = classid;
61 	res->class = 0;
62 	return tcf_exts_exec(skb, &head->exts, res);
63 }
64 
65 static unsigned long cls_cgroup_get(struct tcf_proto *tp, u32 handle)
66 {
67 	return 0UL;
68 }
69 
70 static void cls_cgroup_put(struct tcf_proto *tp, unsigned long f)
71 {
72 }
73 
74 static int cls_cgroup_init(struct tcf_proto *tp)
75 {
76 	return 0;
77 }
78 
79 static const struct nla_policy cgroup_policy[TCA_CGROUP_MAX + 1] = {
80 	[TCA_CGROUP_EMATCHES]	= { .type = NLA_NESTED },
81 };
82 
83 static void cls_cgroup_destroy_rcu(struct rcu_head *root)
84 {
85 	struct cls_cgroup_head *head = container_of(root,
86 						    struct cls_cgroup_head,
87 						    rcu);
88 
89 	tcf_exts_destroy(&head->exts);
90 	tcf_em_tree_destroy(&head->ematches);
91 	kfree(head);
92 }
93 
94 static int cls_cgroup_change(struct net *net, struct sk_buff *in_skb,
95 			     struct tcf_proto *tp, unsigned long base,
96 			     u32 handle, struct nlattr **tca,
97 			     unsigned long *arg, bool ovr)
98 {
99 	struct nlattr *tb[TCA_CGROUP_MAX + 1];
100 	struct cls_cgroup_head *head = rtnl_dereference(tp->root);
101 	struct cls_cgroup_head *new;
102 	struct tcf_ematch_tree t;
103 	struct tcf_exts e;
104 	int err;
105 
106 	if (!tca[TCA_OPTIONS])
107 		return -EINVAL;
108 
109 	if (!head && !handle)
110 		return -EINVAL;
111 
112 	if (head && handle != head->handle)
113 		return -ENOENT;
114 
115 	new = kzalloc(sizeof(*head), GFP_KERNEL);
116 	if (!new)
117 		return -ENOBUFS;
118 
119 	tcf_exts_init(&new->exts, TCA_CGROUP_ACT, TCA_CGROUP_POLICE);
120 	if (head)
121 		new->handle = head->handle;
122 	else
123 		new->handle = handle;
124 
125 	new->tp = tp;
126 	err = nla_parse_nested(tb, TCA_CGROUP_MAX, tca[TCA_OPTIONS],
127 			       cgroup_policy);
128 	if (err < 0)
129 		goto errout;
130 
131 	tcf_exts_init(&e, TCA_CGROUP_ACT, TCA_CGROUP_POLICE);
132 	err = tcf_exts_validate(net, tp, tb, tca[TCA_RATE], &e, ovr);
133 	if (err < 0)
134 		goto errout;
135 
136 	err = tcf_em_tree_validate(tp, tb[TCA_CGROUP_EMATCHES], &t);
137 	if (err < 0) {
138 		tcf_exts_destroy(&e);
139 		goto errout;
140 	}
141 
142 	tcf_exts_change(tp, &new->exts, &e);
143 	tcf_em_tree_change(tp, &new->ematches, &t);
144 
145 	rcu_assign_pointer(tp->root, new);
146 	if (head)
147 		call_rcu(&head->rcu, cls_cgroup_destroy_rcu);
148 	return 0;
149 errout:
150 	kfree(new);
151 	return err;
152 }
153 
154 static void cls_cgroup_destroy(struct tcf_proto *tp)
155 {
156 	struct cls_cgroup_head *head = rtnl_dereference(tp->root);
157 
158 	if (head) {
159 		RCU_INIT_POINTER(tp->root, NULL);
160 		call_rcu(&head->rcu, cls_cgroup_destroy_rcu);
161 	}
162 }
163 
164 static int cls_cgroup_delete(struct tcf_proto *tp, unsigned long arg)
165 {
166 	return -EOPNOTSUPP;
167 }
168 
169 static void cls_cgroup_walk(struct tcf_proto *tp, struct tcf_walker *arg)
170 {
171 	struct cls_cgroup_head *head = rtnl_dereference(tp->root);
172 
173 	if (arg->count < arg->skip)
174 		goto skip;
175 
176 	if (arg->fn(tp, (unsigned long) head, arg) < 0) {
177 		arg->stop = 1;
178 		return;
179 	}
180 skip:
181 	arg->count++;
182 }
183 
184 static int cls_cgroup_dump(struct net *net, struct tcf_proto *tp, unsigned long fh,
185 			   struct sk_buff *skb, struct tcmsg *t)
186 {
187 	struct cls_cgroup_head *head = rtnl_dereference(tp->root);
188 	unsigned char *b = skb_tail_pointer(skb);
189 	struct nlattr *nest;
190 
191 	t->tcm_handle = head->handle;
192 
193 	nest = nla_nest_start(skb, TCA_OPTIONS);
194 	if (nest == NULL)
195 		goto nla_put_failure;
196 
197 	if (tcf_exts_dump(skb, &head->exts) < 0 ||
198 	    tcf_em_tree_dump(skb, &head->ematches, TCA_CGROUP_EMATCHES) < 0)
199 		goto nla_put_failure;
200 
201 	nla_nest_end(skb, nest);
202 
203 	if (tcf_exts_dump_stats(skb, &head->exts) < 0)
204 		goto nla_put_failure;
205 
206 	return skb->len;
207 
208 nla_put_failure:
209 	nlmsg_trim(skb, b);
210 	return -1;
211 }
212 
213 static struct tcf_proto_ops cls_cgroup_ops __read_mostly = {
214 	.kind		=	"cgroup",
215 	.init		=	cls_cgroup_init,
216 	.change		=	cls_cgroup_change,
217 	.classify	=	cls_cgroup_classify,
218 	.destroy	=	cls_cgroup_destroy,
219 	.get		=	cls_cgroup_get,
220 	.put		=	cls_cgroup_put,
221 	.delete		=	cls_cgroup_delete,
222 	.walk		=	cls_cgroup_walk,
223 	.dump		=	cls_cgroup_dump,
224 	.owner		=	THIS_MODULE,
225 };
226 
227 static int __init init_cgroup_cls(void)
228 {
229 	return register_tcf_proto_ops(&cls_cgroup_ops);
230 }
231 
232 static void __exit exit_cgroup_cls(void)
233 {
234 	unregister_tcf_proto_ops(&cls_cgroup_ops);
235 }
236 
237 module_init(init_cgroup_cls);
238 module_exit(exit_cgroup_cls);
239 MODULE_LICENSE("GPL");
240