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	if (!tb[TCA_SAMPLE_PARMS] || !tb[TCA_SAMPLE_RATE] ||
 59	    !tb[TCA_SAMPLE_PSAMPLE_GROUP])
 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 0;
 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	err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack);
 84	if (err < 0)
 85		goto release_idr;
 86
 87	rate = nla_get_u32(tb[TCA_SAMPLE_RATE]);
 88	if (!rate) {
 89		NL_SET_ERR_MSG(extack, "invalid sample rate");
 90		err = -EINVAL;
 91		goto put_chain;
 92	}
 93	psample_group_num = nla_get_u32(tb[TCA_SAMPLE_PSAMPLE_GROUP]);
 94	psample_group = psample_group_get(net, psample_group_num);
 95	if (!psample_group) {
 96		err = -ENOMEM;
 97		goto put_chain;
 98	}
 99
100	s = to_sample(*a);
101
102	spin_lock_bh(&s->tcf_lock);
103	goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
104	s->rate = rate;
105	s->psample_group_num = psample_group_num;
106	psample_group = rcu_replace_pointer(s->psample_group, psample_group,
107					    lockdep_is_held(&s->tcf_lock));
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
115	if (psample_group)
116		psample_group_put(psample_group);
117	if (goto_ch)
118		tcf_chain_put_by_act(goto_ch);
119
120	return ret;
121put_chain:
122	if (goto_ch)
123		tcf_chain_put_by_act(goto_ch);
124release_idr:
125	tcf_idr_release(*a, bind);
126	return err;
127}
128
129static void tcf_sample_cleanup(struct tc_action *a)
130{
131	struct tcf_sample *s = to_sample(a);
132	struct psample_group *psample_group;
133
134	/* last reference to action, no need to lock */
135	psample_group = rcu_dereference_protected(s->psample_group, 1);
136	RCU_INIT_POINTER(s->psample_group, NULL);
137	if (psample_group)
138		psample_group_put(psample_group);
139}
140
141static bool tcf_sample_dev_ok_push(struct net_device *dev)
142{
143	switch (dev->type) {
144	case ARPHRD_TUNNEL:
145	case ARPHRD_TUNNEL6:
146	case ARPHRD_SIT:
147	case ARPHRD_IPGRE:
148	case ARPHRD_IP6GRE:
149	case ARPHRD_VOID:
150	case ARPHRD_NONE:
151		return false;
152	default:
153		return true;
154	}
155}
156
157TC_INDIRECT_SCOPE int tcf_sample_act(struct sk_buff *skb,
158				     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	struct psample_metadata md = {};
164	int retval;
165
166	tcf_lastuse_update(&s->tcf_tm);
167	bstats_update(this_cpu_ptr(s->common.cpu_bstats), skb);
168	retval = READ_ONCE(s->tcf_action);
169
170	psample_group = rcu_dereference_bh(s->psample_group);
171
172	/* randomly sample packets according to rate */
173	if (psample_group && (get_random_u32_below(s->rate) == 0)) {
174		if (!skb_at_tc_ingress(skb)) {
175			md.in_ifindex = skb->skb_iif;
176			md.out_ifindex = skb->dev->ifindex;
177		} else {
178			md.in_ifindex = skb->dev->ifindex;
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		md.trunc_size = s->truncate ? s->trunc_size : skb->len;
186		psample_sample_packet(psample_group, skb, s->rate, &md);
187
188		if (skb_at_tc_ingress(skb) && tcf_sample_dev_ok_push(skb->dev))
189			skb_pull(skb, skb->mac_len);
190	}
191
192	return retval;
193}
194
195static void tcf_sample_stats_update(struct tc_action *a, u64 bytes, u64 packets,
196				    u64 drops, u64 lastuse, bool hw)
197{
198	struct tcf_sample *s = to_sample(a);
199	struct tcf_t *tm = &s->tcf_tm;
200
201	tcf_action_update_stats(a, bytes, packets, drops, hw);
202	tm->lastuse = max_t(u64, tm->lastuse, lastuse);
203}
204
205static int tcf_sample_dump(struct sk_buff *skb, struct tc_action *a,
206			   int bind, int ref)
207{
208	unsigned char *b = skb_tail_pointer(skb);
209	struct tcf_sample *s = to_sample(a);
210	struct tc_sample opt = {
211		.index      = s->tcf_index,
212		.refcnt     = refcount_read(&s->tcf_refcnt) - ref,
213		.bindcnt    = atomic_read(&s->tcf_bindcnt) - bind,
214	};
215	struct tcf_t t;
216
217	spin_lock_bh(&s->tcf_lock);
218	opt.action = s->tcf_action;
219	if (nla_put(skb, TCA_SAMPLE_PARMS, sizeof(opt), &opt))
220		goto nla_put_failure;
221
222	tcf_tm_dump(&t, &s->tcf_tm);
223	if (nla_put_64bit(skb, TCA_SAMPLE_TM, sizeof(t), &t, TCA_SAMPLE_PAD))
224		goto nla_put_failure;
225
226	if (nla_put_u32(skb, TCA_SAMPLE_RATE, s->rate))
227		goto nla_put_failure;
228
229	if (s->truncate)
230		if (nla_put_u32(skb, TCA_SAMPLE_TRUNC_SIZE, s->trunc_size))
231			goto nla_put_failure;
232
233	if (nla_put_u32(skb, TCA_SAMPLE_PSAMPLE_GROUP, s->psample_group_num))
234		goto nla_put_failure;
235	spin_unlock_bh(&s->tcf_lock);
236
237	return skb->len;
238
239nla_put_failure:
240	spin_unlock_bh(&s->tcf_lock);
241	nlmsg_trim(skb, b);
242	return -1;
243}
244
245static void tcf_psample_group_put(void *priv)
246{
247	struct psample_group *group = priv;
248
249	psample_group_put(group);
250}
251
252static struct psample_group *
253tcf_sample_get_group(const struct tc_action *a,
254		     tc_action_priv_destructor *destructor)
255{
256	struct tcf_sample *s = to_sample(a);
257	struct psample_group *group;
258
259	group = rcu_dereference_protected(s->psample_group,
260					  lockdep_is_held(&s->tcf_lock));
261	if (group) {
262		psample_group_take(group);
263		*destructor = tcf_psample_group_put;
264	}
265
266	return group;
267}
268
269static void tcf_offload_sample_get_group(struct flow_action_entry *entry,
270					 const struct tc_action *act)
271{
272	entry->sample.psample_group =
273		act->ops->get_psample_group(act, &entry->destructor);
274	entry->destructor_priv = entry->sample.psample_group;
275}
276
277static int tcf_sample_offload_act_setup(struct tc_action *act, void *entry_data,
278					u32 *index_inc, bool bind,
279					struct netlink_ext_ack *extack)
280{
281	if (bind) {
282		struct flow_action_entry *entry = entry_data;
283
284		entry->id = FLOW_ACTION_SAMPLE;
285		entry->sample.trunc_size = tcf_sample_trunc_size(act);
286		entry->sample.truncate = tcf_sample_truncate(act);
287		entry->sample.rate = tcf_sample_rate(act);
288		tcf_offload_sample_get_group(entry, act);
289		*index_inc = 1;
290	} else {
291		struct flow_offload_action *fl_action = entry_data;
292
293		fl_action->id = FLOW_ACTION_SAMPLE;
294	}
295
296	return 0;
297}
298
299static struct tc_action_ops act_sample_ops = {
300	.kind	  = "sample",
301	.id	  = TCA_ID_SAMPLE,
302	.owner	  = THIS_MODULE,
303	.act	  = tcf_sample_act,
304	.stats_update = tcf_sample_stats_update,
305	.dump	  = tcf_sample_dump,
306	.init	  = tcf_sample_init,
307	.cleanup  = tcf_sample_cleanup,
308	.get_psample_group = tcf_sample_get_group,
309	.offload_act_setup    = tcf_sample_offload_act_setup,
310	.size	  = sizeof(struct tcf_sample),
311};
312
313static __net_init int sample_init_net(struct net *net)
314{
315	struct tc_action_net *tn = net_generic(net, act_sample_ops.net_id);
316
317	return tc_action_net_init(net, tn, &act_sample_ops);
318}
319
320static void __net_exit sample_exit_net(struct list_head *net_list)
321{
322	tc_action_net_exit(net_list, act_sample_ops.net_id);
323}
324
325static struct pernet_operations sample_net_ops = {
326	.init = sample_init_net,
327	.exit_batch = sample_exit_net,
328	.id   = &act_sample_ops.net_id,
329	.size = sizeof(struct tc_action_net),
330};
331
332static int __init sample_init_module(void)
333{
334	return tcf_register_action(&act_sample_ops, &sample_net_ops);
335}
336
337static void __exit sample_cleanup_module(void)
338{
339	tcf_unregister_action(&act_sample_ops, &sample_net_ops);
340}
341
342module_init(sample_init_module);
343module_exit(sample_cleanup_module);
344
345MODULE_AUTHOR("Yotam Gigi <yotam.gi@gmail.com>");
346MODULE_DESCRIPTION("Packet sampling action");
347MODULE_LICENSE("GPL v2");