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#include <net/tc_wrapper.h>
 24
 25#include <linux/if_arp.h>
 26
 27static struct tc_action_ops act_sample_ops;
 28
 29static 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
 36static int tcf_sample_init(struct net *net, struct nlattr *nla,
 37			   struct nlattr *est, struct tc_action **a,
 38			   struct tcf_proto *tp,
 39			   u32 flags, struct netlink_ext_ack *extack)
 40{
 41	struct tc_action_net *tn = net_generic(net, act_sample_ops.net_id);
 42	bool bind = flags & TCA_ACT_FLAGS_BIND;
 43	struct nlattr *tb[TCA_SAMPLE_MAX + 1];
 44	struct psample_group *psample_group;
 45	u32 psample_group_num, rate, index;
 46	struct tcf_chain *goto_ch = NULL;
 47	struct tc_sample *parm;
 48	struct tcf_sample *s;
 49	bool exists = false;
 50	int ret, err;
 51
 52	if (!nla)
 53		return -EINVAL;
 54	ret = nla_parse_nested_deprecated(tb, TCA_SAMPLE_MAX, nla,
 55					  sample_policy, NULL);
 56	if (ret < 0)
 57		return ret;
 58
 59	if (!tb[TCA_SAMPLE_PARMS])
 60		return -EINVAL;
 61
 62	parm = nla_data(tb[TCA_SAMPLE_PARMS]);
 63	index = parm->index;
 64	err = tcf_idr_check_alloc(tn, &index, a, bind);
 65	if (err < 0)
 66		return err;
 67	exists = err;
 68	if (exists && bind)
 69		return ACT_P_BOUND;
 70
 71	if (!exists) {
 72		ret = tcf_idr_create(tn, index, est, a,
 73				     &act_sample_ops, bind, true, flags);
 74		if (ret) {
 75			tcf_idr_cleanup(tn, index);
 76			return ret;
 77		}
 78		ret = ACT_P_CREATED;
 79	} else if (!(flags & TCA_ACT_FLAGS_REPLACE)) {
 80		tcf_idr_release(*a, bind);
 81		return -EEXIST;
 82	}
 83
 84	if (!tb[TCA_SAMPLE_RATE] || !tb[TCA_SAMPLE_PSAMPLE_GROUP]) {
 85		NL_SET_ERR_MSG(extack, "sample rate and group are required");
 86		err = -EINVAL;
 87		goto release_idr;
 88	}
 89
 90	err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack);
 91	if (err < 0)
 92		goto release_idr;
 93
 94	rate = nla_get_u32(tb[TCA_SAMPLE_RATE]);
 95	if (!rate) {
 96		NL_SET_ERR_MSG(extack, "invalid sample rate");
 97		err = -EINVAL;
 98		goto put_chain;
 99	}
100	psample_group_num = nla_get_u32(tb[TCA_SAMPLE_PSAMPLE_GROUP]);
101	psample_group = psample_group_get(net, psample_group_num);
102	if (!psample_group) {
103		err = -ENOMEM;
104		goto put_chain;
105	}
106
107	s = to_sample(*a);
108
109	spin_lock_bh(&s->tcf_lock);
110	goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
111	s->rate = rate;
112	s->psample_group_num = psample_group_num;
113	psample_group = rcu_replace_pointer(s->psample_group, psample_group,
114					    lockdep_is_held(&s->tcf_lock));
115
116	if (tb[TCA_SAMPLE_TRUNC_SIZE]) {
117		s->truncate = true;
118		s->trunc_size = nla_get_u32(tb[TCA_SAMPLE_TRUNC_SIZE]);
119	}
120	spin_unlock_bh(&s->tcf_lock);
121
122	if (psample_group)
123		psample_group_put(psample_group);
124	if (goto_ch)
125		tcf_chain_put_by_act(goto_ch);
126
127	return ret;
128put_chain:
129	if (goto_ch)
130		tcf_chain_put_by_act(goto_ch);
131release_idr:
132	tcf_idr_release(*a, bind);
133	return err;
134}
135
136static void tcf_sample_cleanup(struct tc_action *a)
137{
138	struct tcf_sample *s = to_sample(a);
139	struct psample_group *psample_group;
140
141	/* last reference to action, no need to lock */
142	psample_group = rcu_dereference_protected(s->psample_group, 1);
143	RCU_INIT_POINTER(s->psample_group, NULL);
144	if (psample_group)
145		psample_group_put(psample_group);
146}
147
148static bool tcf_sample_dev_ok_push(struct net_device *dev)
149{
150	switch (dev->type) {
151	case ARPHRD_TUNNEL:
152	case ARPHRD_TUNNEL6:
153	case ARPHRD_SIT:
154	case ARPHRD_IPGRE:
155	case ARPHRD_IP6GRE:
156	case ARPHRD_VOID:
157	case ARPHRD_NONE:
158		return false;
159	default:
160		return true;
161	}
162}
163
164TC_INDIRECT_SCOPE int tcf_sample_act(struct sk_buff *skb,
165				     const struct tc_action *a,
166				     struct tcf_result *res)
167{
168	struct tcf_sample *s = to_sample(a);
169	struct psample_group *psample_group;
170	u8 cookie_data[TC_COOKIE_MAX_SIZE];
171	struct psample_metadata md = {};
172	struct tc_cookie *user_cookie;
173	int retval;
174
175	tcf_lastuse_update(&s->tcf_tm);
176	bstats_update(this_cpu_ptr(s->common.cpu_bstats), skb);
177	retval = READ_ONCE(s->tcf_action);
178
179	psample_group = rcu_dereference_bh(s->psample_group);
180
181	/* randomly sample packets according to rate */
182	if (psample_group && (get_random_u32_below(s->rate) == 0)) {
183		if (!skb_at_tc_ingress(skb)) {
184			md.in_ifindex = skb->skb_iif;
185			md.out_ifindex = skb->dev->ifindex;
186		} else {
187			md.in_ifindex = skb->dev->ifindex;
188		}
189
190		/* on ingress, the mac header gets popped, so push it back */
191		if (skb_at_tc_ingress(skb) && tcf_sample_dev_ok_push(skb->dev))
192			skb_push(skb, skb->mac_len);
193
194		rcu_read_lock();
195		user_cookie = rcu_dereference(a->user_cookie);
196		if (user_cookie) {
197			memcpy(cookie_data, user_cookie->data,
198			       user_cookie->len);
199			md.user_cookie = cookie_data;
200			md.user_cookie_len = user_cookie->len;
201		}
202		rcu_read_unlock();
203
204		md.trunc_size = s->truncate ? s->trunc_size : skb->len;
205		psample_sample_packet(psample_group, skb, s->rate, &md);
206
207		if (skb_at_tc_ingress(skb) && tcf_sample_dev_ok_push(skb->dev))
208			skb_pull(skb, skb->mac_len);
209	}
210
211	return retval;
212}
213
214static void tcf_sample_stats_update(struct tc_action *a, u64 bytes, u64 packets,
215				    u64 drops, u64 lastuse, bool hw)
216{
217	struct tcf_sample *s = to_sample(a);
218	struct tcf_t *tm = &s->tcf_tm;
219
220	tcf_action_update_stats(a, bytes, packets, drops, hw);
221	tm->lastuse = max_t(u64, tm->lastuse, lastuse);
222}
223
224static int tcf_sample_dump(struct sk_buff *skb, struct tc_action *a,
225			   int bind, int ref)
226{
227	unsigned char *b = skb_tail_pointer(skb);
228	struct tcf_sample *s = to_sample(a);
229	struct tc_sample opt = {
230		.index      = s->tcf_index,
231		.refcnt     = refcount_read(&s->tcf_refcnt) - ref,
232		.bindcnt    = atomic_read(&s->tcf_bindcnt) - bind,
233	};
234	struct tcf_t t;
235
236	spin_lock_bh(&s->tcf_lock);
237	opt.action = s->tcf_action;
238	if (nla_put(skb, TCA_SAMPLE_PARMS, sizeof(opt), &opt))
239		goto nla_put_failure;
240
241	tcf_tm_dump(&t, &s->tcf_tm);
242	if (nla_put_64bit(skb, TCA_SAMPLE_TM, sizeof(t), &t, TCA_SAMPLE_PAD))
243		goto nla_put_failure;
244
245	if (nla_put_u32(skb, TCA_SAMPLE_RATE, s->rate))
246		goto nla_put_failure;
247
248	if (s->truncate)
249		if (nla_put_u32(skb, TCA_SAMPLE_TRUNC_SIZE, s->trunc_size))
250			goto nla_put_failure;
251
252	if (nla_put_u32(skb, TCA_SAMPLE_PSAMPLE_GROUP, s->psample_group_num))
253		goto nla_put_failure;
254	spin_unlock_bh(&s->tcf_lock);
255
256	return skb->len;
257
258nla_put_failure:
259	spin_unlock_bh(&s->tcf_lock);
260	nlmsg_trim(skb, b);
261	return -1;
262}
263
264static void tcf_psample_group_put(void *priv)
265{
266	struct psample_group *group = priv;
267
268	psample_group_put(group);
269}
270
271static struct psample_group *
272tcf_sample_get_group(const struct tc_action *a,
273		     tc_action_priv_destructor *destructor)
274{
275	struct tcf_sample *s = to_sample(a);
276	struct psample_group *group;
277
278	group = rcu_dereference_protected(s->psample_group,
279					  lockdep_is_held(&s->tcf_lock));
280	if (group) {
281		psample_group_take(group);
282		*destructor = tcf_psample_group_put;
283	}
284
285	return group;
286}
287
288static void tcf_offload_sample_get_group(struct flow_action_entry *entry,
289					 const struct tc_action *act)
290{
291	entry->sample.psample_group =
292		act->ops->get_psample_group(act, &entry->destructor);
293	entry->destructor_priv = entry->sample.psample_group;
294}
295
296static int tcf_sample_offload_act_setup(struct tc_action *act, void *entry_data,
297					u32 *index_inc, bool bind,
298					struct netlink_ext_ack *extack)
299{
300	if (bind) {
301		struct flow_action_entry *entry = entry_data;
302
303		entry->id = FLOW_ACTION_SAMPLE;
304		entry->sample.trunc_size = tcf_sample_trunc_size(act);
305		entry->sample.truncate = tcf_sample_truncate(act);
306		entry->sample.rate = tcf_sample_rate(act);
307		tcf_offload_sample_get_group(entry, act);
308		*index_inc = 1;
309	} else {
310		struct flow_offload_action *fl_action = entry_data;
311
312		fl_action->id = FLOW_ACTION_SAMPLE;
313	}
314
315	return 0;
316}
317
318static struct tc_action_ops act_sample_ops = {
319	.kind	  = "sample",
320	.id	  = TCA_ID_SAMPLE,
321	.owner	  = THIS_MODULE,
322	.act	  = tcf_sample_act,
323	.stats_update = tcf_sample_stats_update,
324	.dump	  = tcf_sample_dump,
325	.init	  = tcf_sample_init,
326	.cleanup  = tcf_sample_cleanup,
327	.get_psample_group = tcf_sample_get_group,
328	.offload_act_setup    = tcf_sample_offload_act_setup,
329	.size	  = sizeof(struct tcf_sample),
330};
331MODULE_ALIAS_NET_ACT("sample");
332
333static __net_init int sample_init_net(struct net *net)
334{
335	struct tc_action_net *tn = net_generic(net, act_sample_ops.net_id);
336
337	return tc_action_net_init(net, tn, &act_sample_ops);
338}
339
340static void __net_exit sample_exit_net(struct list_head *net_list)
341{
342	tc_action_net_exit(net_list, act_sample_ops.net_id);
343}
344
345static struct pernet_operations sample_net_ops = {
346	.init = sample_init_net,
347	.exit_batch = sample_exit_net,
348	.id   = &act_sample_ops.net_id,
349	.size = sizeof(struct tc_action_net),
350};
351
352static int __init sample_init_module(void)
353{
354	return tcf_register_action(&act_sample_ops, &sample_net_ops);
355}
356
357static void __exit sample_cleanup_module(void)
358{
359	tcf_unregister_action(&act_sample_ops, &sample_net_ops);
360}
361
362module_init(sample_init_module);
363module_exit(sample_cleanup_module);
364
365MODULE_AUTHOR("Yotam Gigi <yotam.gi@gmail.com>");
366MODULE_DESCRIPTION("Packet sampling action");
367MODULE_LICENSE("GPL v2");