xref: /openbmc/linux/net/sched/act_sample.c (revision 62e59c4e)
1 /*
2  * net/sched/act_sample.c - Packet sampling tc action
3  * Copyright (c) 2017 Yotam Gigi <yotamg@mellanox.com>
4  *
5  * This program is free software; you can redistribute it and/or modify
6  * it under the terms of the GNU General Public License version 2 as
7  * published by the Free Software Foundation.
8  */
9 
10 #include <linux/types.h>
11 #include <linux/kernel.h>
12 #include <linux/string.h>
13 #include <linux/errno.h>
14 #include <linux/skbuff.h>
15 #include <linux/rtnetlink.h>
16 #include <linux/module.h>
17 #include <linux/init.h>
18 #include <linux/gfp.h>
19 #include <net/net_namespace.h>
20 #include <net/netlink.h>
21 #include <net/pkt_sched.h>
22 #include <linux/tc_act/tc_sample.h>
23 #include <net/tc_act/tc_sample.h>
24 #include <net/psample.h>
25 #include <net/pkt_cls.h>
26 
27 #include <linux/if_arp.h>
28 
29 static unsigned int sample_net_id;
30 static struct tc_action_ops act_sample_ops;
31 
32 static const struct nla_policy sample_policy[TCA_SAMPLE_MAX + 1] = {
33 	[TCA_SAMPLE_PARMS]		= { .len = sizeof(struct tc_sample) },
34 	[TCA_SAMPLE_RATE]		= { .type = NLA_U32 },
35 	[TCA_SAMPLE_TRUNC_SIZE]		= { .type = NLA_U32 },
36 	[TCA_SAMPLE_PSAMPLE_GROUP]	= { .type = NLA_U32 },
37 };
38 
39 static int tcf_sample_init(struct net *net, struct nlattr *nla,
40 			   struct nlattr *est, struct tc_action **a, int ovr,
41 			   int bind, bool rtnl_held, struct tcf_proto *tp,
42 			   struct netlink_ext_ack *extack)
43 {
44 	struct tc_action_net *tn = net_generic(net, sample_net_id);
45 	struct nlattr *tb[TCA_SAMPLE_MAX + 1];
46 	struct psample_group *psample_group;
47 	struct tcf_chain *goto_ch = NULL;
48 	u32 psample_group_num, rate;
49 	struct tc_sample *parm;
50 	struct tcf_sample *s;
51 	bool exists = false;
52 	int ret, err;
53 
54 	if (!nla)
55 		return -EINVAL;
56 	ret = nla_parse_nested(tb, TCA_SAMPLE_MAX, nla, sample_policy, NULL);
57 	if (ret < 0)
58 		return ret;
59 	if (!tb[TCA_SAMPLE_PARMS] || !tb[TCA_SAMPLE_RATE] ||
60 	    !tb[TCA_SAMPLE_PSAMPLE_GROUP])
61 		return -EINVAL;
62 
63 	parm = nla_data(tb[TCA_SAMPLE_PARMS]);
64 
65 	err = tcf_idr_check_alloc(tn, &parm->index, a, bind);
66 	if (err < 0)
67 		return err;
68 	exists = err;
69 	if (exists && bind)
70 		return 0;
71 
72 	if (!exists) {
73 		ret = tcf_idr_create(tn, parm->index, est, a,
74 				     &act_sample_ops, bind, true);
75 		if (ret) {
76 			tcf_idr_cleanup(tn, parm->index);
77 			return ret;
78 		}
79 		ret = ACT_P_CREATED;
80 	} else if (!ovr) {
81 		tcf_idr_release(*a, bind);
82 		return -EEXIST;
83 	}
84 	err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack);
85 	if (err < 0)
86 		goto release_idr;
87 
88 	rate = nla_get_u32(tb[TCA_SAMPLE_RATE]);
89 	if (!rate) {
90 		NL_SET_ERR_MSG(extack, "invalid sample rate");
91 		err = -EINVAL;
92 		goto put_chain;
93 	}
94 	psample_group_num = nla_get_u32(tb[TCA_SAMPLE_PSAMPLE_GROUP]);
95 	psample_group = psample_group_get(net, psample_group_num);
96 	if (!psample_group) {
97 		err = -ENOMEM;
98 		goto put_chain;
99 	}
100 
101 	s = to_sample(*a);
102 
103 	spin_lock_bh(&s->tcf_lock);
104 	goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
105 	s->rate = rate;
106 	s->psample_group_num = psample_group_num;
107 	RCU_INIT_POINTER(s->psample_group, psample_group);
108 
109 	if (tb[TCA_SAMPLE_TRUNC_SIZE]) {
110 		s->truncate = true;
111 		s->trunc_size = nla_get_u32(tb[TCA_SAMPLE_TRUNC_SIZE]);
112 	}
113 	spin_unlock_bh(&s->tcf_lock);
114 	if (goto_ch)
115 		tcf_chain_put_by_act(goto_ch);
116 
117 	if (ret == ACT_P_CREATED)
118 		tcf_idr_insert(tn, *a);
119 	return ret;
120 put_chain:
121 	if (goto_ch)
122 		tcf_chain_put_by_act(goto_ch);
123 release_idr:
124 	tcf_idr_release(*a, bind);
125 	return err;
126 }
127 
128 static void tcf_sample_cleanup(struct tc_action *a)
129 {
130 	struct tcf_sample *s = to_sample(a);
131 	struct psample_group *psample_group;
132 
133 	/* last reference to action, no need to lock */
134 	psample_group = rcu_dereference_protected(s->psample_group, 1);
135 	RCU_INIT_POINTER(s->psample_group, NULL);
136 	if (psample_group)
137 		psample_group_put(psample_group);
138 }
139 
140 static bool tcf_sample_dev_ok_push(struct net_device *dev)
141 {
142 	switch (dev->type) {
143 	case ARPHRD_TUNNEL:
144 	case ARPHRD_TUNNEL6:
145 	case ARPHRD_SIT:
146 	case ARPHRD_IPGRE:
147 	case ARPHRD_VOID:
148 	case ARPHRD_NONE:
149 		return false;
150 	default:
151 		return true;
152 	}
153 }
154 
155 static int tcf_sample_act(struct sk_buff *skb, const struct tc_action *a,
156 			  struct tcf_result *res)
157 {
158 	struct tcf_sample *s = to_sample(a);
159 	struct psample_group *psample_group;
160 	int retval;
161 	int size;
162 	int iif;
163 	int oif;
164 
165 	tcf_lastuse_update(&s->tcf_tm);
166 	bstats_cpu_update(this_cpu_ptr(s->common.cpu_bstats), skb);
167 	retval = READ_ONCE(s->tcf_action);
168 
169 	psample_group = rcu_dereference_bh(s->psample_group);
170 
171 	/* randomly sample packets according to rate */
172 	if (psample_group && (prandom_u32() % s->rate == 0)) {
173 		if (!skb_at_tc_ingress(skb)) {
174 			iif = skb->skb_iif;
175 			oif = skb->dev->ifindex;
176 		} else {
177 			iif = skb->dev->ifindex;
178 			oif = 0;
179 		}
180 
181 		/* on ingress, the mac header gets popped, so push it back */
182 		if (skb_at_tc_ingress(skb) && tcf_sample_dev_ok_push(skb->dev))
183 			skb_push(skb, skb->mac_len);
184 
185 		size = s->truncate ? s->trunc_size : skb->len;
186 		psample_sample_packet(psample_group, skb, size, iif, oif,
187 				      s->rate);
188 
189 		if (skb_at_tc_ingress(skb) && tcf_sample_dev_ok_push(skb->dev))
190 			skb_pull(skb, skb->mac_len);
191 	}
192 
193 	return retval;
194 }
195 
196 static int tcf_sample_dump(struct sk_buff *skb, struct tc_action *a,
197 			   int bind, int ref)
198 {
199 	unsigned char *b = skb_tail_pointer(skb);
200 	struct tcf_sample *s = to_sample(a);
201 	struct tc_sample opt = {
202 		.index      = s->tcf_index,
203 		.refcnt     = refcount_read(&s->tcf_refcnt) - ref,
204 		.bindcnt    = atomic_read(&s->tcf_bindcnt) - bind,
205 	};
206 	struct tcf_t t;
207 
208 	spin_lock_bh(&s->tcf_lock);
209 	opt.action = s->tcf_action;
210 	if (nla_put(skb, TCA_SAMPLE_PARMS, sizeof(opt), &opt))
211 		goto nla_put_failure;
212 
213 	tcf_tm_dump(&t, &s->tcf_tm);
214 	if (nla_put_64bit(skb, TCA_SAMPLE_TM, sizeof(t), &t, TCA_SAMPLE_PAD))
215 		goto nla_put_failure;
216 
217 	if (nla_put_u32(skb, TCA_SAMPLE_RATE, s->rate))
218 		goto nla_put_failure;
219 
220 	if (s->truncate)
221 		if (nla_put_u32(skb, TCA_SAMPLE_TRUNC_SIZE, s->trunc_size))
222 			goto nla_put_failure;
223 
224 	if (nla_put_u32(skb, TCA_SAMPLE_PSAMPLE_GROUP, s->psample_group_num))
225 		goto nla_put_failure;
226 	spin_unlock_bh(&s->tcf_lock);
227 
228 	return skb->len;
229 
230 nla_put_failure:
231 	spin_unlock_bh(&s->tcf_lock);
232 	nlmsg_trim(skb, b);
233 	return -1;
234 }
235 
236 static int tcf_sample_walker(struct net *net, struct sk_buff *skb,
237 			     struct netlink_callback *cb, int type,
238 			     const struct tc_action_ops *ops,
239 			     struct netlink_ext_ack *extack)
240 {
241 	struct tc_action_net *tn = net_generic(net, sample_net_id);
242 
243 	return tcf_generic_walker(tn, skb, cb, type, ops, extack);
244 }
245 
246 static int tcf_sample_search(struct net *net, struct tc_action **a, u32 index)
247 {
248 	struct tc_action_net *tn = net_generic(net, sample_net_id);
249 
250 	return tcf_idr_search(tn, a, index);
251 }
252 
253 static struct tc_action_ops act_sample_ops = {
254 	.kind	  = "sample",
255 	.id	  = TCA_ID_SAMPLE,
256 	.owner	  = THIS_MODULE,
257 	.act	  = tcf_sample_act,
258 	.dump	  = tcf_sample_dump,
259 	.init	  = tcf_sample_init,
260 	.cleanup  = tcf_sample_cleanup,
261 	.walk	  = tcf_sample_walker,
262 	.lookup	  = tcf_sample_search,
263 	.size	  = sizeof(struct tcf_sample),
264 };
265 
266 static __net_init int sample_init_net(struct net *net)
267 {
268 	struct tc_action_net *tn = net_generic(net, sample_net_id);
269 
270 	return tc_action_net_init(tn, &act_sample_ops);
271 }
272 
273 static void __net_exit sample_exit_net(struct list_head *net_list)
274 {
275 	tc_action_net_exit(net_list, sample_net_id);
276 }
277 
278 static struct pernet_operations sample_net_ops = {
279 	.init = sample_init_net,
280 	.exit_batch = sample_exit_net,
281 	.id   = &sample_net_id,
282 	.size = sizeof(struct tc_action_net),
283 };
284 
285 static int __init sample_init_module(void)
286 {
287 	return tcf_register_action(&act_sample_ops, &sample_net_ops);
288 }
289 
290 static void __exit sample_cleanup_module(void)
291 {
292 	tcf_unregister_action(&act_sample_ops, &sample_net_ops);
293 }
294 
295 module_init(sample_init_module);
296 module_exit(sample_cleanup_module);
297 
298 MODULE_AUTHOR("Yotam Gigi <yotam.gi@gmail.com>");
299 MODULE_DESCRIPTION("Packet sampling action");
300 MODULE_LICENSE("GPL v2");
301