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Linux/net/sched/act_sample.c

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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 
 26 static unsigned int sample_net_id;
 27 static struct tc_action_ops act_sample_ops;
 28 
 29 static 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 
 36 static 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;
120 put_chain:
121         if (goto_ch)
122                 tcf_chain_put_by_act(goto_ch);
123 release_idr:
124         tcf_idr_release(*a, bind);
125         return err;
126 }
127 
128 static 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 
140 static 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 
156 static 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 
197 static 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 
231 nla_put_failure:
232         spin_unlock_bh(&s->tcf_lock);
233         nlmsg_trim(skb, b);
234         return -1;
235 }
236 
237 static 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 
247 static 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 
254 static void tcf_psample_group_put(void *priv)
255 {
256         struct psample_group *group = priv;
257 
258         psample_group_put(group);
259 }
260 
261 static struct psample_group *
262 tcf_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 
278 static 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 
292 static __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 
299 static void __net_exit sample_exit_net(struct list_head *net_list)
300 {
301         tc_action_net_exit(net_list, sample_net_id);
302 }
303 
304 static 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 
311 static int __init sample_init_module(void)
312 {
313         return tcf_register_action(&act_sample_ops, &sample_net_ops);
314 }
315 
316 static void __exit sample_cleanup_module(void)
317 {
318         tcf_unregister_action(&act_sample_ops, &sample_net_ops);
319 }
320 
321 module_init(sample_init_module);
322 module_exit(sample_cleanup_module);
323 
324 MODULE_AUTHOR("Yotam Gigi <yotam.gi@gmail.com>");
325 MODULE_DESCRIPTION("Packet sampling action");
326 MODULE_LICENSE("GPL v2");
327 

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