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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
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 int retval;
162 int size;
163 int iif;
164 int oif;
165
166 tcf_lastuse_update(&s->tcf_tm);
167 bstats_cpu_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 && (prandom_u32() % s->rate == 0)) {
174 if (!skb_at_tc_ingress(skb)) {
175 iif = skb->skb_iif;
176 oif = skb->dev->ifindex;
177 } else {
178 iif = skb->dev->ifindex;
179 oif = 0;
180 }
181
182 /* on ingress, the mac header gets popped, so push it back */
183 if (skb_at_tc_ingress(skb) && tcf_sample_dev_ok_push(skb->dev))
184 skb_push(skb, skb->mac_len);
185
186 size = s->truncate ? s->trunc_size : skb->len;
187 psample_sample_packet(psample_group, skb, size, iif, oif,
188 s->rate);
189
190 if (skb_at_tc_ingress(skb) && tcf_sample_dev_ok_push(skb->dev))
191 skb_pull(skb, skb->mac_len);
192 }
193
194 return retval;
195}
196
197static int tcf_sample_dump(struct sk_buff *skb, struct tc_action *a,
198 int bind, int ref)
199{
200 unsigned char *b = skb_tail_pointer(skb);
201 struct tcf_sample *s = to_sample(a);
202 struct tc_sample opt = {
203 .index = s->tcf_index,
204 .refcnt = refcount_read(&s->tcf_refcnt) - ref,
205 .bindcnt = atomic_read(&s->tcf_bindcnt) - bind,
206 };
207 struct tcf_t t;
208
209 spin_lock_bh(&s->tcf_lock);
210 opt.action = s->tcf_action;
211 if (nla_put(skb, TCA_SAMPLE_PARMS, sizeof(opt), &opt))
212 goto nla_put_failure;
213
214 tcf_tm_dump(&t, &s->tcf_tm);
215 if (nla_put_64bit(skb, TCA_SAMPLE_TM, sizeof(t), &t, TCA_SAMPLE_PAD))
216 goto nla_put_failure;
217
218 if (nla_put_u32(skb, TCA_SAMPLE_RATE, s->rate))
219 goto nla_put_failure;
220
221 if (s->truncate)
222 if (nla_put_u32(skb, TCA_SAMPLE_TRUNC_SIZE, s->trunc_size))
223 goto nla_put_failure;
224
225 if (nla_put_u32(skb, TCA_SAMPLE_PSAMPLE_GROUP, s->psample_group_num))
226 goto nla_put_failure;
227 spin_unlock_bh(&s->tcf_lock);
228
229 return skb->len;
230
231nla_put_failure:
232 spin_unlock_bh(&s->tcf_lock);
233 nlmsg_trim(skb, b);
234 return -1;
235}
236
237static int tcf_sample_walker(struct net *net, struct sk_buff *skb,
238 struct netlink_callback *cb, int type,
239 const struct tc_action_ops *ops,
240 struct netlink_ext_ack *extack)
241{
242 struct tc_action_net *tn = net_generic(net, sample_net_id);
243
244 return tcf_generic_walker(tn, skb, cb, type, ops, extack);
245}
246
247static int tcf_sample_search(struct net *net, struct tc_action **a, u32 index)
248{
249 struct tc_action_net *tn = net_generic(net, sample_net_id);
250
251 return tcf_idr_search(tn, a, index);
252}
253
254static void tcf_psample_group_put(void *priv)
255{
256 struct psample_group *group = priv;
257
258 psample_group_put(group);
259}
260
261static struct psample_group *
262tcf_sample_get_group(const struct tc_action *a,
263 tc_action_priv_destructor *destructor)
264{
265 struct tcf_sample *s = to_sample(a);
266 struct psample_group *group;
267
268 group = rcu_dereference_protected(s->psample_group,
269 lockdep_is_held(&s->tcf_lock));
270 if (group) {
271 psample_group_take(group);
272 *destructor = tcf_psample_group_put;
273 }
274
275 return group;
276}
277
278static struct tc_action_ops act_sample_ops = {
279 .kind = "sample",
280 .id = TCA_ID_SAMPLE,
281 .owner = THIS_MODULE,
282 .act = tcf_sample_act,
283 .dump = tcf_sample_dump,
284 .init = tcf_sample_init,
285 .cleanup = tcf_sample_cleanup,
286 .walk = tcf_sample_walker,
287 .lookup = tcf_sample_search,
288 .get_psample_group = tcf_sample_get_group,
289 .size = sizeof(struct tcf_sample),
290};
291
292static __net_init int sample_init_net(struct net *net)
293{
294 struct tc_action_net *tn = net_generic(net, sample_net_id);
295
296 return tc_action_net_init(net, tn, &act_sample_ops);
297}
298
299static void __net_exit sample_exit_net(struct list_head *net_list)
300{
301 tc_action_net_exit(net_list, sample_net_id);
302}
303
304static struct pernet_operations sample_net_ops = {
305 .init = sample_init_net,
306 .exit_batch = sample_exit_net,
307 .id = &sample_net_id,
308 .size = sizeof(struct tc_action_net),
309};
310
311static int __init sample_init_module(void)
312{
313 return tcf_register_action(&act_sample_ops, &sample_net_ops);
314}
315
316static void __exit sample_cleanup_module(void)
317{
318 tcf_unregister_action(&act_sample_ops, &sample_net_ops);
319}
320
321module_init(sample_init_module);
322module_exit(sample_cleanup_module);
323
324MODULE_AUTHOR("Yotam Gigi <yotam.gi@gmail.com>");
325MODULE_DESCRIPTION("Packet sampling action");
326MODULE_LICENSE("GPL v2");