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			   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;
122put_chain:
123	if (goto_ch)
124		tcf_chain_put_by_act(goto_ch);
125release_idr:
126	tcf_idr_release(*a, bind);
127	return err;
128}
129
130static 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
142static 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
158static 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
199static 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
233nla_put_failure:
234	spin_unlock_bh(&s->tcf_lock);
235	nlmsg_trim(skb, b);
236	return -1;
237}
238
239static 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
249static 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
256static void tcf_psample_group_put(void *priv)
257{
258	struct psample_group *group = priv;
259
260	psample_group_put(group);
261}
262
263static struct psample_group *
264tcf_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
282static 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
296static __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
303static void __net_exit sample_exit_net(struct list_head *net_list)
304{
305	tc_action_net_exit(net_list, sample_net_id);
306}
307
308static 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
315static int __init sample_init_module(void)
316{
317	return tcf_register_action(&act_sample_ops, &sample_net_ops);
318}
319
320static void __exit sample_cleanup_module(void)
321{
322	tcf_unregister_action(&act_sample_ops, &sample_net_ops);
323}
324
325module_init(sample_init_module);
326module_exit(sample_cleanup_module);
327
328MODULE_AUTHOR("Yotam Gigi <yotam.gi@gmail.com>");
329MODULE_DESCRIPTION("Packet sampling action");
330MODULE_LICENSE("GPL v2");