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1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * net/sched/act_sample.c - Packet sampling tc action
4  * Copyright (c) 2017 Yotam Gigi <yotamg@mellanox.com>
5  */
6 
7 #include <linux/types.h>
8 #include <linux/kernel.h>
9 #include <linux/string.h>
10 #include <linux/errno.h>
11 #include <linux/skbuff.h>
12 #include <linux/rtnetlink.h>
13 #include <linux/module.h>
14 #include <linux/init.h>
15 #include <linux/gfp.h>
16 #include <net/net_namespace.h>
17 #include <net/netlink.h>
18 #include <net/pkt_sched.h>
19 #include <linux/tc_act/tc_sample.h>
20 #include <net/tc_act/tc_sample.h>
21 #include <net/psample.h>
22 #include <net/pkt_cls.h>
23 
24 #include <linux/if_arp.h>
25 
26 static unsigned int sample_net_id;
27 static struct tc_action_ops act_sample_ops;
28 
29 static const struct nla_policy sample_policy[TCA_SAMPLE_MAX + 1] = {
30 	[TCA_SAMPLE_PARMS]		= { .len = sizeof(struct tc_sample) },
31 	[TCA_SAMPLE_RATE]		= { .type = NLA_U32 },
32 	[TCA_SAMPLE_TRUNC_SIZE]		= { .type = NLA_U32 },
33 	[TCA_SAMPLE_PSAMPLE_GROUP]	= { .type = NLA_U32 },
34 };
35 
tcf_sample_init(struct net * net,struct nlattr * nla,struct nlattr * est,struct tc_action ** a,int ovr,int bind,bool rtnl_held,struct tcf_proto * tp,struct netlink_ext_ack * extack)36 static int tcf_sample_init(struct net *net, struct nlattr *nla,
37 			   struct nlattr *est, struct tc_action **a, int ovr,
38 			   int bind, bool rtnl_held, struct tcf_proto *tp,
39 			   struct netlink_ext_ack *extack)
40 {
41 	struct tc_action_net *tn = net_generic(net, sample_net_id);
42 	struct nlattr *tb[TCA_SAMPLE_MAX + 1];
43 	struct psample_group *psample_group;
44 	u32 psample_group_num, rate, index;
45 	struct tcf_chain *goto_ch = NULL;
46 	struct tc_sample *parm;
47 	struct tcf_sample *s;
48 	bool exists = false;
49 	int ret, err;
50 
51 	if (!nla)
52 		return -EINVAL;
53 	ret = nla_parse_nested_deprecated(tb, TCA_SAMPLE_MAX, nla,
54 					  sample_policy, NULL);
55 	if (ret < 0)
56 		return ret;
57 	if (!tb[TCA_SAMPLE_PARMS] || !tb[TCA_SAMPLE_RATE] ||
58 	    !tb[TCA_SAMPLE_PSAMPLE_GROUP])
59 		return -EINVAL;
60 
61 	parm = nla_data(tb[TCA_SAMPLE_PARMS]);
62 	index = parm->index;
63 	err = tcf_idr_check_alloc(tn, &index, a, bind);
64 	if (err < 0)
65 		return err;
66 	exists = err;
67 	if (exists && bind)
68 		return 0;
69 
70 	if (!exists) {
71 		ret = tcf_idr_create(tn, index, est, a,
72 				     &act_sample_ops, bind, true);
73 		if (ret) {
74 			tcf_idr_cleanup(tn, index);
75 			return ret;
76 		}
77 		ret = ACT_P_CREATED;
78 	} else if (!ovr) {
79 		tcf_idr_release(*a, bind);
80 		return -EEXIST;
81 	}
82 	err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack);
83 	if (err < 0)
84 		goto release_idr;
85 
86 	rate = nla_get_u32(tb[TCA_SAMPLE_RATE]);
87 	if (!rate) {
88 		NL_SET_ERR_MSG(extack, "invalid sample rate");
89 		err = -EINVAL;
90 		goto put_chain;
91 	}
92 	psample_group_num = nla_get_u32(tb[TCA_SAMPLE_PSAMPLE_GROUP]);
93 	psample_group = psample_group_get(net, psample_group_num);
94 	if (!psample_group) {
95 		err = -ENOMEM;
96 		goto put_chain;
97 	}
98 
99 	s = to_sample(*a);
100 
101 	spin_lock_bh(&s->tcf_lock);
102 	goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
103 	s->rate = rate;
104 	s->psample_group_num = psample_group_num;
105 	rcu_swap_protected(s->psample_group, psample_group,
106 			   lockdep_is_held(&s->tcf_lock));
107 
108 	if (tb[TCA_SAMPLE_TRUNC_SIZE]) {
109 		s->truncate = true;
110 		s->trunc_size = nla_get_u32(tb[TCA_SAMPLE_TRUNC_SIZE]);
111 	}
112 	spin_unlock_bh(&s->tcf_lock);
113 
114 	if (psample_group)
115 		psample_group_put(psample_group);
116 	if (goto_ch)
117 		tcf_chain_put_by_act(goto_ch);
118 
119 	if (ret == ACT_P_CREATED)
120 		tcf_idr_insert(tn, *a);
121 	return ret;
122 put_chain:
123 	if (goto_ch)
124 		tcf_chain_put_by_act(goto_ch);
125 release_idr:
126 	tcf_idr_release(*a, bind);
127 	return err;
128 }
129 
tcf_sample_cleanup(struct tc_action * a)130 static void tcf_sample_cleanup(struct tc_action *a)
131 {
132 	struct tcf_sample *s = to_sample(a);
133 	struct psample_group *psample_group;
134 
135 	/* last reference to action, no need to lock */
136 	psample_group = rcu_dereference_protected(s->psample_group, 1);
137 	RCU_INIT_POINTER(s->psample_group, NULL);
138 	if (psample_group)
139 		psample_group_put(psample_group);
140 }
141 
tcf_sample_dev_ok_push(struct net_device * dev)142 static bool tcf_sample_dev_ok_push(struct net_device *dev)
143 {
144 	switch (dev->type) {
145 	case ARPHRD_TUNNEL:
146 	case ARPHRD_TUNNEL6:
147 	case ARPHRD_SIT:
148 	case ARPHRD_IPGRE:
149 	case ARPHRD_IP6GRE:
150 	case ARPHRD_VOID:
151 	case ARPHRD_NONE:
152 		return false;
153 	default:
154 		return true;
155 	}
156 }
157 
tcf_sample_act(struct sk_buff * skb,const struct tc_action * a,struct tcf_result * res)158 static int tcf_sample_act(struct sk_buff *skb, const struct tc_action *a,
159 			  struct tcf_result *res)
160 {
161 	struct tcf_sample *s = to_sample(a);
162 	struct psample_group *psample_group;
163 	int retval;
164 	int size;
165 	int iif;
166 	int oif;
167 
168 	tcf_lastuse_update(&s->tcf_tm);
169 	bstats_cpu_update(this_cpu_ptr(s->common.cpu_bstats), skb);
170 	retval = READ_ONCE(s->tcf_action);
171 
172 	psample_group = rcu_dereference_bh(s->psample_group);
173 
174 	/* randomly sample packets according to rate */
175 	if (psample_group && (prandom_u32() % s->rate == 0)) {
176 		if (!skb_at_tc_ingress(skb)) {
177 			iif = skb->skb_iif;
178 			oif = skb->dev->ifindex;
179 		} else {
180 			iif = skb->dev->ifindex;
181 			oif = 0;
182 		}
183 
184 		/* on ingress, the mac header gets popped, so push it back */
185 		if (skb_at_tc_ingress(skb) && tcf_sample_dev_ok_push(skb->dev))
186 			skb_push(skb, skb->mac_len);
187 
188 		size = s->truncate ? s->trunc_size : skb->len;
189 		psample_sample_packet(psample_group, skb, size, iif, oif,
190 				      s->rate);
191 
192 		if (skb_at_tc_ingress(skb) && tcf_sample_dev_ok_push(skb->dev))
193 			skb_pull(skb, skb->mac_len);
194 	}
195 
196 	return retval;
197 }
198 
tcf_sample_dump(struct sk_buff * skb,struct tc_action * a,int bind,int ref)199 static int tcf_sample_dump(struct sk_buff *skb, struct tc_action *a,
200 			   int bind, int ref)
201 {
202 	unsigned char *b = skb_tail_pointer(skb);
203 	struct tcf_sample *s = to_sample(a);
204 	struct tc_sample opt = {
205 		.index      = s->tcf_index,
206 		.refcnt     = refcount_read(&s->tcf_refcnt) - ref,
207 		.bindcnt    = atomic_read(&s->tcf_bindcnt) - bind,
208 	};
209 	struct tcf_t t;
210 
211 	spin_lock_bh(&s->tcf_lock);
212 	opt.action = s->tcf_action;
213 	if (nla_put(skb, TCA_SAMPLE_PARMS, sizeof(opt), &opt))
214 		goto nla_put_failure;
215 
216 	tcf_tm_dump(&t, &s->tcf_tm);
217 	if (nla_put_64bit(skb, TCA_SAMPLE_TM, sizeof(t), &t, TCA_SAMPLE_PAD))
218 		goto nla_put_failure;
219 
220 	if (nla_put_u32(skb, TCA_SAMPLE_RATE, s->rate))
221 		goto nla_put_failure;
222 
223 	if (s->truncate)
224 		if (nla_put_u32(skb, TCA_SAMPLE_TRUNC_SIZE, s->trunc_size))
225 			goto nla_put_failure;
226 
227 	if (nla_put_u32(skb, TCA_SAMPLE_PSAMPLE_GROUP, s->psample_group_num))
228 		goto nla_put_failure;
229 	spin_unlock_bh(&s->tcf_lock);
230 
231 	return skb->len;
232 
233 nla_put_failure:
234 	spin_unlock_bh(&s->tcf_lock);
235 	nlmsg_trim(skb, b);
236 	return -1;
237 }
238 
tcf_sample_walker(struct net * net,struct sk_buff * skb,struct netlink_callback * cb,int type,const struct tc_action_ops * ops,struct netlink_ext_ack * extack)239 static int tcf_sample_walker(struct net *net, struct sk_buff *skb,
240 			     struct netlink_callback *cb, int type,
241 			     const struct tc_action_ops *ops,
242 			     struct netlink_ext_ack *extack)
243 {
244 	struct tc_action_net *tn = net_generic(net, sample_net_id);
245 
246 	return tcf_generic_walker(tn, skb, cb, type, ops, extack);
247 }
248 
tcf_sample_search(struct net * net,struct tc_action ** a,u32 index)249 static int tcf_sample_search(struct net *net, struct tc_action **a, u32 index)
250 {
251 	struct tc_action_net *tn = net_generic(net, sample_net_id);
252 
253 	return tcf_idr_search(tn, a, index);
254 }
255 
tcf_psample_group_put(void * priv)256 static void tcf_psample_group_put(void *priv)
257 {
258 	struct psample_group *group = priv;
259 
260 	psample_group_put(group);
261 }
262 
263 static struct psample_group *
tcf_sample_get_group(const struct tc_action * a,tc_action_priv_destructor * destructor)264 tcf_sample_get_group(const struct tc_action *a,
265 		     tc_action_priv_destructor *destructor)
266 {
267 	struct tcf_sample *s = to_sample(a);
268 	struct psample_group *group;
269 
270 	spin_lock_bh(&s->tcf_lock);
271 	group = rcu_dereference_protected(s->psample_group,
272 					  lockdep_is_held(&s->tcf_lock));
273 	if (group) {
274 		psample_group_take(group);
275 		*destructor = tcf_psample_group_put;
276 	}
277 	spin_unlock_bh(&s->tcf_lock);
278 
279 	return group;
280 }
281 
282 static struct tc_action_ops act_sample_ops = {
283 	.kind	  = "sample",
284 	.id	  = TCA_ID_SAMPLE,
285 	.owner	  = THIS_MODULE,
286 	.act	  = tcf_sample_act,
287 	.dump	  = tcf_sample_dump,
288 	.init	  = tcf_sample_init,
289 	.cleanup  = tcf_sample_cleanup,
290 	.walk	  = tcf_sample_walker,
291 	.lookup	  = tcf_sample_search,
292 	.get_psample_group = tcf_sample_get_group,
293 	.size	  = sizeof(struct tcf_sample),
294 };
295 
sample_init_net(struct net * net)296 static __net_init int sample_init_net(struct net *net)
297 {
298 	struct tc_action_net *tn = net_generic(net, sample_net_id);
299 
300 	return tc_action_net_init(net, tn, &act_sample_ops);
301 }
302 
sample_exit_net(struct list_head * net_list)303 static void __net_exit sample_exit_net(struct list_head *net_list)
304 {
305 	tc_action_net_exit(net_list, sample_net_id);
306 }
307 
308 static struct pernet_operations sample_net_ops = {
309 	.init = sample_init_net,
310 	.exit_batch = sample_exit_net,
311 	.id   = &sample_net_id,
312 	.size = sizeof(struct tc_action_net),
313 };
314 
sample_init_module(void)315 static int __init sample_init_module(void)
316 {
317 	return tcf_register_action(&act_sample_ops, &sample_net_ops);
318 }
319 
sample_cleanup_module(void)320 static void __exit sample_cleanup_module(void)
321 {
322 	tcf_unregister_action(&act_sample_ops, &sample_net_ops);
323 }
324 
325 module_init(sample_init_module);
326 module_exit(sample_cleanup_module);
327 
328 MODULE_AUTHOR("Yotam Gigi <yotam.gi@gmail.com>");
329 MODULE_DESCRIPTION("Packet sampling action");
330 MODULE_LICENSE("GPL v2");
331