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Linux/net/sched/act_sample.c

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  1 /*
  2  * net/sched/act_sample.c - Packet sampling tc action
  3  * Copyright (c) 2017 Yotam Gigi <yotamg@mellanox.com>
  4  *
  5  * This program is free software; you can redistribute it and/or modify
  6  * it under the terms of the GNU General Public License version 2 as
  7  * published by the Free Software Foundation.
  8  */
  9 
 10 #include <linux/types.h>
 11 #include <linux/kernel.h>
 12 #include <linux/string.h>
 13 #include <linux/errno.h>
 14 #include <linux/skbuff.h>
 15 #include <linux/rtnetlink.h>
 16 #include <linux/module.h>
 17 #include <linux/init.h>
 18 #include <linux/gfp.h>
 19 #include <net/net_namespace.h>
 20 #include <net/netlink.h>
 21 #include <net/pkt_sched.h>
 22 #include <linux/tc_act/tc_sample.h>
 23 #include <net/tc_act/tc_sample.h>
 24 #include <net/psample.h>
 25 
 26 #include <linux/if_arp.h>
 27 
 28 static unsigned int sample_net_id;
 29 static struct tc_action_ops act_sample_ops;
 30 
 31 static const struct nla_policy sample_policy[TCA_SAMPLE_MAX + 1] = {
 32         [TCA_SAMPLE_PARMS]              = { .len = sizeof(struct tc_sample) },
 33         [TCA_SAMPLE_RATE]               = { .type = NLA_U32 },
 34         [TCA_SAMPLE_TRUNC_SIZE]         = { .type = NLA_U32 },
 35         [TCA_SAMPLE_PSAMPLE_GROUP]      = { .type = NLA_U32 },
 36 };
 37 
 38 static int tcf_sample_init(struct net *net, struct nlattr *nla,
 39                            struct nlattr *est, struct tc_action **a, int ovr,
 40                            int bind)
 41 {
 42         struct tc_action_net *tn = net_generic(net, sample_net_id);
 43         struct nlattr *tb[TCA_SAMPLE_MAX + 1];
 44         struct psample_group *psample_group;
 45         struct tc_sample *parm;
 46         struct tcf_sample *s;
 47         bool exists = false;
 48         int ret;
 49 
 50         if (!nla)
 51                 return -EINVAL;
 52         ret = nla_parse_nested(tb, TCA_SAMPLE_MAX, nla, sample_policy, NULL);
 53         if (ret < 0)
 54                 return ret;
 55         if (!tb[TCA_SAMPLE_PARMS] || !tb[TCA_SAMPLE_RATE] ||
 56             !tb[TCA_SAMPLE_PSAMPLE_GROUP])
 57                 return -EINVAL;
 58 
 59         parm = nla_data(tb[TCA_SAMPLE_PARMS]);
 60 
 61         exists = tcf_idr_check(tn, parm->index, a, bind);
 62         if (exists && bind)
 63                 return 0;
 64 
 65         if (!exists) {
 66                 ret = tcf_idr_create(tn, parm->index, est, a,
 67                                      &act_sample_ops, bind, false);
 68                 if (ret)
 69                         return ret;
 70                 ret = ACT_P_CREATED;
 71         } else {
 72                 tcf_idr_release(*a, bind);
 73                 if (!ovr)
 74                         return -EEXIST;
 75         }
 76         s = to_sample(*a);
 77 
 78         s->tcf_action = parm->action;
 79         s->rate = nla_get_u32(tb[TCA_SAMPLE_RATE]);
 80         s->psample_group_num = nla_get_u32(tb[TCA_SAMPLE_PSAMPLE_GROUP]);
 81         psample_group = psample_group_get(net, s->psample_group_num);
 82         if (!psample_group) {
 83                 if (ret == ACT_P_CREATED)
 84                         tcf_idr_release(*a, bind);
 85                 return -ENOMEM;
 86         }
 87         RCU_INIT_POINTER(s->psample_group, psample_group);
 88 
 89         if (tb[TCA_SAMPLE_TRUNC_SIZE]) {
 90                 s->truncate = true;
 91                 s->trunc_size = nla_get_u32(tb[TCA_SAMPLE_TRUNC_SIZE]);
 92         }
 93 
 94         if (ret == ACT_P_CREATED)
 95                 tcf_idr_insert(tn, *a);
 96         return ret;
 97 }
 98 
 99 static void tcf_sample_cleanup(struct tc_action *a)
100 {
101         struct tcf_sample *s = to_sample(a);
102         struct psample_group *psample_group;
103 
104         psample_group = rtnl_dereference(s->psample_group);
105         RCU_INIT_POINTER(s->psample_group, NULL);
106         if (psample_group)
107                 psample_group_put(psample_group);
108 }
109 
110 static bool tcf_sample_dev_ok_push(struct net_device *dev)
111 {
112         switch (dev->type) {
113         case ARPHRD_TUNNEL:
114         case ARPHRD_TUNNEL6:
115         case ARPHRD_SIT:
116         case ARPHRD_IPGRE:
117         case ARPHRD_VOID:
118         case ARPHRD_NONE:
119                 return false;
120         default:
121                 return true;
122         }
123 }
124 
125 static int tcf_sample_act(struct sk_buff *skb, const struct tc_action *a,
126                           struct tcf_result *res)
127 {
128         struct tcf_sample *s = to_sample(a);
129         struct psample_group *psample_group;
130         int retval;
131         int size;
132         int iif;
133         int oif;
134 
135         tcf_lastuse_update(&s->tcf_tm);
136         bstats_cpu_update(this_cpu_ptr(s->common.cpu_bstats), skb);
137         retval = READ_ONCE(s->tcf_action);
138 
139         rcu_read_lock();
140         psample_group = rcu_dereference(s->psample_group);
141 
142         /* randomly sample packets according to rate */
143         if (psample_group && (prandom_u32() % s->rate == 0)) {
144                 if (!skb_at_tc_ingress(skb)) {
145                         iif = skb->skb_iif;
146                         oif = skb->dev->ifindex;
147                 } else {
148                         iif = skb->dev->ifindex;
149                         oif = 0;
150                 }
151 
152                 /* on ingress, the mac header gets popped, so push it back */
153                 if (skb_at_tc_ingress(skb) && tcf_sample_dev_ok_push(skb->dev))
154                         skb_push(skb, skb->mac_len);
155 
156                 size = s->truncate ? s->trunc_size : skb->len;
157                 psample_sample_packet(psample_group, skb, size, iif, oif,
158                                       s->rate);
159 
160                 if (skb_at_tc_ingress(skb) && tcf_sample_dev_ok_push(skb->dev))
161                         skb_pull(skb, skb->mac_len);
162         }
163 
164         rcu_read_unlock();
165         return retval;
166 }
167 
168 static int tcf_sample_dump(struct sk_buff *skb, struct tc_action *a,
169                            int bind, int ref)
170 {
171         unsigned char *b = skb_tail_pointer(skb);
172         struct tcf_sample *s = to_sample(a);
173         struct tc_sample opt = {
174                 .index      = s->tcf_index,
175                 .action     = s->tcf_action,
176                 .refcnt     = s->tcf_refcnt - ref,
177                 .bindcnt    = s->tcf_bindcnt - bind,
178         };
179         struct tcf_t t;
180 
181         if (nla_put(skb, TCA_SAMPLE_PARMS, sizeof(opt), &opt))
182                 goto nla_put_failure;
183 
184         tcf_tm_dump(&t, &s->tcf_tm);
185         if (nla_put_64bit(skb, TCA_SAMPLE_TM, sizeof(t), &t, TCA_SAMPLE_PAD))
186                 goto nla_put_failure;
187 
188         if (nla_put_u32(skb, TCA_SAMPLE_RATE, s->rate))
189                 goto nla_put_failure;
190 
191         if (s->truncate)
192                 if (nla_put_u32(skb, TCA_SAMPLE_TRUNC_SIZE, s->trunc_size))
193                         goto nla_put_failure;
194 
195         if (nla_put_u32(skb, TCA_SAMPLE_PSAMPLE_GROUP, s->psample_group_num))
196                 goto nla_put_failure;
197         return skb->len;
198 
199 nla_put_failure:
200         nlmsg_trim(skb, b);
201         return -1;
202 }
203 
204 static int tcf_sample_walker(struct net *net, struct sk_buff *skb,
205                              struct netlink_callback *cb, int type,
206                              const struct tc_action_ops *ops)
207 {
208         struct tc_action_net *tn = net_generic(net, sample_net_id);
209 
210         return tcf_generic_walker(tn, skb, cb, type, ops);
211 }
212 
213 static int tcf_sample_search(struct net *net, struct tc_action **a, u32 index)
214 {
215         struct tc_action_net *tn = net_generic(net, sample_net_id);
216 
217         return tcf_idr_search(tn, a, index);
218 }
219 
220 static struct tc_action_ops act_sample_ops = {
221         .kind     = "sample",
222         .type     = TCA_ACT_SAMPLE,
223         .owner    = THIS_MODULE,
224         .act      = tcf_sample_act,
225         .dump     = tcf_sample_dump,
226         .init     = tcf_sample_init,
227         .cleanup  = tcf_sample_cleanup,
228         .walk     = tcf_sample_walker,
229         .lookup   = tcf_sample_search,
230         .size     = sizeof(struct tcf_sample),
231 };
232 
233 static __net_init int sample_init_net(struct net *net)
234 {
235         struct tc_action_net *tn = net_generic(net, sample_net_id);
236 
237         return tc_action_net_init(tn, &act_sample_ops);
238 }
239 
240 static void __net_exit sample_exit_net(struct list_head *net_list)
241 {
242         tc_action_net_exit(net_list, sample_net_id);
243 }
244 
245 static struct pernet_operations sample_net_ops = {
246         .init = sample_init_net,
247         .exit_batch = sample_exit_net,
248         .id   = &sample_net_id,
249         .size = sizeof(struct tc_action_net),
250 };
251 
252 static int __init sample_init_module(void)
253 {
254         return tcf_register_action(&act_sample_ops, &sample_net_ops);
255 }
256 
257 static void __exit sample_cleanup_module(void)
258 {
259         tcf_unregister_action(&act_sample_ops, &sample_net_ops);
260 }
261 
262 module_init(sample_init_module);
263 module_exit(sample_cleanup_module);
264 
265 MODULE_AUTHOR("Yotam Gigi <yotam.gi@gmail.com>");
266 MODULE_DESCRIPTION("Packet sampling action");
267 MODULE_LICENSE("GPL v2");
268 

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