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
 26static unsigned int sample_net_id;
 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, int ovr,
 38			   int bind, bool rtnl_held, struct tcf_proto *tp,
 39			   u32 flags, 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, 0);
 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	psample_group = rcu_replace_pointer(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	return ret;
120put_chain:
121	if (goto_ch)
122		tcf_chain_put_by_act(goto_ch);
123release_idr:
124	tcf_idr_release(*a, bind);
125	return err;
126}
127
128static 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
140static 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_IP6GRE:
148	case ARPHRD_VOID:
149	case ARPHRD_NONE:
150		return false;
151	default:
152		return true;
153	}
154}
155
156static int tcf_sample_act(struct sk_buff *skb, const struct tc_action *a,
157			  struct tcf_result *res)
158{
159	struct tcf_sample *s = to_sample(a);
160	struct psample_group *psample_group;
161	struct psample_metadata md = {};
162	int retval;
163
164	tcf_lastuse_update(&s->tcf_tm);
165	bstats_cpu_update(this_cpu_ptr(s->common.cpu_bstats), skb);
166	retval = READ_ONCE(s->tcf_action);
167
168	psample_group = rcu_dereference_bh(s->psample_group);
169
170	/* randomly sample packets according to rate */
171	if (psample_group && (prandom_u32() % s->rate == 0)) {
172		if (!skb_at_tc_ingress(skb)) {
173			md.in_ifindex = skb->skb_iif;
174			md.out_ifindex = skb->dev->ifindex;
175		} else {
176			md.in_ifindex = skb->dev->ifindex;
177		}
178
179		/* on ingress, the mac header gets popped, so push it back */
180		if (skb_at_tc_ingress(skb) && tcf_sample_dev_ok_push(skb->dev))
181			skb_push(skb, skb->mac_len);
182
183		md.trunc_size = s->truncate ? s->trunc_size : skb->len;
184		psample_sample_packet(psample_group, skb, s->rate, &md);
185
186		if (skb_at_tc_ingress(skb) && tcf_sample_dev_ok_push(skb->dev))
187			skb_pull(skb, skb->mac_len);
188	}
189
190	return retval;
191}
192
193static void tcf_sample_stats_update(struct tc_action *a, u64 bytes, u64 packets,
194				    u64 drops, u64 lastuse, bool hw)
195{
196	struct tcf_sample *s = to_sample(a);
197	struct tcf_t *tm = &s->tcf_tm;
198
199	tcf_action_update_stats(a, bytes, packets, drops, hw);
200	tm->lastuse = max_t(u64, tm->lastuse, lastuse);
201}
202
203static int tcf_sample_dump(struct sk_buff *skb, struct tc_action *a,
204			   int bind, int ref)
205{
206	unsigned char *b = skb_tail_pointer(skb);
207	struct tcf_sample *s = to_sample(a);
208	struct tc_sample opt = {
209		.index      = s->tcf_index,
210		.refcnt     = refcount_read(&s->tcf_refcnt) - ref,
211		.bindcnt    = atomic_read(&s->tcf_bindcnt) - bind,
212	};
213	struct tcf_t t;
214
215	spin_lock_bh(&s->tcf_lock);
216	opt.action = s->tcf_action;
217	if (nla_put(skb, TCA_SAMPLE_PARMS, sizeof(opt), &opt))
218		goto nla_put_failure;
219
220	tcf_tm_dump(&t, &s->tcf_tm);
221	if (nla_put_64bit(skb, TCA_SAMPLE_TM, sizeof(t), &t, TCA_SAMPLE_PAD))
222		goto nla_put_failure;
223
224	if (nla_put_u32(skb, TCA_SAMPLE_RATE, s->rate))
225		goto nla_put_failure;
226
227	if (s->truncate)
228		if (nla_put_u32(skb, TCA_SAMPLE_TRUNC_SIZE, s->trunc_size))
229			goto nla_put_failure;
230
231	if (nla_put_u32(skb, TCA_SAMPLE_PSAMPLE_GROUP, s->psample_group_num))
232		goto nla_put_failure;
233	spin_unlock_bh(&s->tcf_lock);
234
235	return skb->len;
236
237nla_put_failure:
238	spin_unlock_bh(&s->tcf_lock);
239	nlmsg_trim(skb, b);
240	return -1;
241}
242
243static int tcf_sample_walker(struct net *net, struct sk_buff *skb,
244			     struct netlink_callback *cb, int type,
245			     const struct tc_action_ops *ops,
246			     struct netlink_ext_ack *extack)
247{
248	struct tc_action_net *tn = net_generic(net, sample_net_id);
249
250	return tcf_generic_walker(tn, skb, cb, type, ops, extack);
251}
252
253static int tcf_sample_search(struct net *net, struct tc_action **a, u32 index)
254{
255	struct tc_action_net *tn = net_generic(net, sample_net_id);
256
257	return tcf_idr_search(tn, a, index);
258}
259
260static void tcf_psample_group_put(void *priv)
261{
262	struct psample_group *group = priv;
263
264	psample_group_put(group);
265}
266
267static struct psample_group *
268tcf_sample_get_group(const struct tc_action *a,
269		     tc_action_priv_destructor *destructor)
270{
271	struct tcf_sample *s = to_sample(a);
272	struct psample_group *group;
273
274	group = rcu_dereference_protected(s->psample_group,
275					  lockdep_is_held(&s->tcf_lock));
276	if (group) {
277		psample_group_take(group);
278		*destructor = tcf_psample_group_put;
279	}
280
281	return group;
282}
283
284static struct tc_action_ops act_sample_ops = {
285	.kind	  = "sample",
286	.id	  = TCA_ID_SAMPLE,
287	.owner	  = THIS_MODULE,
288	.act	  = tcf_sample_act,
289	.stats_update = tcf_sample_stats_update,
290	.dump	  = tcf_sample_dump,
291	.init	  = tcf_sample_init,
292	.cleanup  = tcf_sample_cleanup,
293	.walk	  = tcf_sample_walker,
294	.lookup	  = tcf_sample_search,
295	.get_psample_group = tcf_sample_get_group,
296	.size	  = sizeof(struct tcf_sample),
297};
298
299static __net_init int sample_init_net(struct net *net)
300{
301	struct tc_action_net *tn = net_generic(net, sample_net_id);
302
303	return tc_action_net_init(net, tn, &act_sample_ops);
304}
305
306static void __net_exit sample_exit_net(struct list_head *net_list)
307{
308	tc_action_net_exit(net_list, sample_net_id);
309}
310
311static struct pernet_operations sample_net_ops = {
312	.init = sample_init_net,
313	.exit_batch = sample_exit_net,
314	.id   = &sample_net_id,
315	.size = sizeof(struct tc_action_net),
316};
317
318static int __init sample_init_module(void)
319{
320	return tcf_register_action(&act_sample_ops, &sample_net_ops);
321}
322
323static void __exit sample_cleanup_module(void)
324{
325	tcf_unregister_action(&act_sample_ops, &sample_net_ops);
326}
327
328module_init(sample_init_module);
329module_exit(sample_cleanup_module);
330
331MODULE_AUTHOR("Yotam Gigi <yotam.gi@gmail.com>");
332MODULE_DESCRIPTION("Packet sampling action");
333MODULE_LICENSE("GPL v2");