net/sched/act_sample.c

   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 <[email protected]>
   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 #include <net/tc_wrapper.h>
  24
  25 #include <linux/if_arp.h>
  26
  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,
  38                            struct tcf_proto *tp,
  39                            u32 flags, struct netlink_ext_ack *extack)
  40 {
  41         struct tc_action_net *tn = net_generic(net, act_sample_ops.net_id);
  42         bool bind = flags & TCA_ACT_FLAGS_BIND;
  43         struct nlattr *tb[TCA_SAMPLE_MAX + 1];
  44         struct psample_group *psample_group;
  45         u32 psample_group_num, rate, index;
  46         struct tcf_chain *goto_ch = NULL;
  47         struct tc_sample *parm;
  48         struct tcf_sample *s;
  49         bool exists = false;
  50         int ret, err;
  51
  52         if (!nla)
  53                 return -EINVAL;
  54         ret = nla_parse_nested_deprecated(tb, TCA_SAMPLE_MAX, nla,
  55                                           sample_policy, NULL);
  56         if (ret < 0)
  57                 return ret;
  58
  59         if (!tb[TCA_SAMPLE_PARMS])
  60                 return -EINVAL;
  61
  62         parm = nla_data(tb[TCA_SAMPLE_PARMS]);
  63         index = parm->index;
  64         err = tcf_idr_check_alloc(tn, &index, a, bind);
  65         if (err < 0)
  66                 return err;
  67         exists = err;
  68         if (exists && bind)
  69                 return ACT_P_BOUND;
  70
  71         if (!exists) {
  72                 ret = tcf_idr_create(tn, index, est, a,
  73                                      &act_sample_ops, bind, true, flags);
  74                 if (ret) {
  75                         tcf_idr_cleanup(tn, index);
  76                         return ret;
  77                 }
  78                 ret = ACT_P_CREATED;
  79         } else if (!(flags & TCA_ACT_FLAGS_REPLACE)) {
  80                 tcf_idr_release(*a, bind);
  81                 return -EEXIST;
  82         }
  83
  84         if (!tb[TCA_SAMPLE_RATE] || !tb[TCA_SAMPLE_PSAMPLE_GROUP]) {
  85                 NL_SET_ERR_MSG(extack, "sample rate and group are required");
  86                 err = -EINVAL;
  87                 goto release_idr;
  88         }
  89
  90         err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack);
  91         if (err < 0)
  92                 goto release_idr;
  93
  94         rate = nla_get_u32(tb[TCA_SAMPLE_RATE]);
  95         if (!rate) {
  96                 NL_SET_ERR_MSG(extack, "invalid sample rate");
  97                 err = -EINVAL;
  98                 goto put_chain;
  99         }
 100         psample_group_num = nla_get_u32(tb[TCA_SAMPLE_PSAMPLE_GROUP]);
 101         psample_group = psample_group_get(net, psample_group_num);
 102         if (!psample_group) {
 103                 err = -ENOMEM;
 104                 goto put_chain;
 105         }
 106
 107         s = to_sample(*a);
 108
 109         spin_lock_bh(&s->tcf_lock);
 110         goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
 111         s->rate = rate;
 112         s->psample_group_num = psample_group_num;
 113         psample_group = rcu_replace_pointer(s->psample_group, psample_group,
 114                                             lockdep_is_held(&s->tcf_lock));
 115
 116         if (tb[TCA_SAMPLE_TRUNC_SIZE]) {
 117                 s->truncate = true;
 118                 s->trunc_size = nla_get_u32(tb[TCA_SAMPLE_TRUNC_SIZE]);
 119         }
 120         spin_unlock_bh(&s->tcf_lock);
 121
 122         if (psample_group)
 123                 psample_group_put(psample_group);
 124         if (goto_ch)
 125                 tcf_chain_put_by_act(goto_ch);
 126
 127         return ret;
 128 put_chain:
 129         if (goto_ch)
 130                 tcf_chain_put_by_act(goto_ch);
 131 release_idr:
 132         tcf_idr_release(*a, bind);
 133         return err;
 134 }
 135
 136 static void tcf_sample_cleanup(struct tc_action *a)
 137 {
 138         struct tcf_sample *s = to_sample(a);
 139         struct psample_group *psample_group;
 140
 141         /* last reference to action, no need to lock */
 142         psample_group = rcu_dereference_protected(s->psample_group, 1);
 143         RCU_INIT_POINTER(s->psample_group, NULL);
 144         if (psample_group)
 145                 psample_group_put(psample_group);
 146 }
 147
 148 static bool tcf_sample_dev_ok_push(struct net_device *dev)
 149 {
 150         switch (dev->type) {
 151         case ARPHRD_TUNNEL:
 152         case ARPHRD_TUNNEL6:
 153         case ARPHRD_SIT:
 154         case ARPHRD_IPGRE:
 155         case ARPHRD_IP6GRE:
 156         case ARPHRD_VOID:
 157         case ARPHRD_NONE:
 158                 return false;
 159         default:
 160                 return true;
 161         }
 162 }
 163
 164 TC_INDIRECT_SCOPE int tcf_sample_act(struct sk_buff *skb,
 165                                      const struct tc_action *a,
 166                                      struct tcf_result *res)
 167 {
 168         struct tcf_sample *s = to_sample(a);
 169         struct psample_group *psample_group;
 170         u8 cookie_data[TC_COOKIE_MAX_SIZE];
 171         struct psample_metadata md = {};
 172         struct tc_cookie *user_cookie;
 173         int retval;
 174
 175         tcf_lastuse_update(&s->tcf_tm);
 176         bstats_update(this_cpu_ptr(s->common.cpu_bstats), skb);
 177         retval = READ_ONCE(s->tcf_action);
 178
 179         psample_group = rcu_dereference_bh(s->psample_group);
 180
 181         /* randomly sample packets according to rate */
 182         if (psample_group && (get_random_u32_below(s->rate) == 0)) {
 183                 if (!skb_at_tc_ingress(skb)) {
 184                         md.in_ifindex = skb->skb_iif;
 185                         md.out_ifindex = skb->dev->ifindex;
 186                 } else {
 187                         md.in_ifindex = skb->dev->ifindex;
 188                 }
 189
 190                 /* on ingress, the mac header gets popped, so push it back */
 191                 if (skb_at_tc_ingress(skb) && tcf_sample_dev_ok_push(skb->dev))
 192                         skb_push(skb, skb->mac_len);
 193
 194                 rcu_read_lock();
 195                 user_cookie = rcu_dereference(a->user_cookie);
 196                 if (user_cookie) {
 197                         memcpy(cookie_data, user_cookie->data,
 198                                user_cookie->len);
 199                         md.user_cookie = cookie_data;
 200                         md.user_cookie_len = user_cookie->len;
 201                 }
 202                 rcu_read_unlock();
 203
 204                 md.trunc_size = s->truncate ? s->trunc_size : skb->len;
 205                 psample_sample_packet(psample_group, skb, s->rate, &md);
 206
 207                 if (skb_at_tc_ingress(skb) && tcf_sample_dev_ok_push(skb->dev))
 208                         skb_pull(skb, skb->mac_len);
 209         }
 210
 211         return retval;
 212 }
 213
 214 static void tcf_sample_stats_update(struct tc_action *a, u64 bytes, u64 packets,
 215                                     u64 drops, u64 lastuse, bool hw)
 216 {
 217         struct tcf_sample *s = to_sample(a);
 218         struct tcf_t *tm = &s->tcf_tm;
 219
 220         tcf_action_update_stats(a, bytes, packets, drops, hw);
 221         tm->lastuse = max_t(u64, tm->lastuse, lastuse);
 222 }
 223
 224 static int tcf_sample_dump(struct sk_buff *skb, struct tc_action *a,
 225                            int bind, int ref)
 226 {
 227         unsigned char *b = skb_tail_pointer(skb);
 228         struct tcf_sample *s = to_sample(a);
 229         struct tc_sample opt = {
 230                 .index      = s->tcf_index,
 231                 .refcnt     = refcount_read(&s->tcf_refcnt) - ref,
 232                 .bindcnt    = atomic_read(&s->tcf_bindcnt) - bind,
 233         };
 234         struct tcf_t t;
 235
 236         spin_lock_bh(&s->tcf_lock);
 237         opt.action = s->tcf_action;
 238         if (nla_put(skb, TCA_SAMPLE_PARMS, sizeof(opt), &opt))
 239                 goto nla_put_failure;
 240
 241         tcf_tm_dump(&t, &s->tcf_tm);
 242         if (nla_put_64bit(skb, TCA_SAMPLE_TM, sizeof(t), &t, TCA_SAMPLE_PAD))
 243                 goto nla_put_failure;
 244
 245         if (nla_put_u32(skb, TCA_SAMPLE_RATE, s->rate))
 246                 goto nla_put_failure;
 247
 248         if (s->truncate)
 249                 if (nla_put_u32(skb, TCA_SAMPLE_TRUNC_SIZE, s->trunc_size))
 250                         goto nla_put_failure;
 251
 252         if (nla_put_u32(skb, TCA_SAMPLE_PSAMPLE_GROUP, s->psample_group_num))
 253                 goto nla_put_failure;
 254         spin_unlock_bh(&s->tcf_lock);
 255
 256         return skb->len;
 257
 258 nla_put_failure:
 259         spin_unlock_bh(&s->tcf_lock);
 260         nlmsg_trim(skb, b);
 261         return -1;
 262 }
 263
 264 static void tcf_psample_group_put(void *priv)
 265 {
 266         struct psample_group *group = priv;
 267
 268         psample_group_put(group);
 269 }
 270
 271 static struct psample_group *
 272 tcf_sample_get_group(const struct tc_action *a,
 273                      tc_action_priv_destructor *destructor)
 274 {
 275         struct tcf_sample *s = to_sample(a);
 276         struct psample_group *group;
 277
 278         group = rcu_dereference_protected(s->psample_group,
 279                                           lockdep_is_held(&s->tcf_lock));
 280         if (group) {
 281                 psample_group_take(group);
 282                 *destructor = tcf_psample_group_put;
 283         }
 284
 285         return group;
 286 }
 287
 288 static void tcf_offload_sample_get_group(struct flow_action_entry *entry,
 289                                          const struct tc_action *act)
 290 {
 291         entry->sample.psample_group =
 292                 act->ops->get_psample_group(act, &entry->destructor);
 293         entry->destructor_priv = entry->sample.psample_group;
 294 }
 295
 296 static int tcf_sample_offload_act_setup(struct tc_action *act, void *entry_data,
 297                                         u32 *index_inc, bool bind,
 298                                         struct netlink_ext_ack *extack)
 299 {
 300         if (bind) {
 301                 struct flow_action_entry *entry = entry_data;
 302
 303                 entry->id = FLOW_ACTION_SAMPLE;
 304                 entry->sample.trunc_size = tcf_sample_trunc_size(act);
 305                 entry->sample.truncate = tcf_sample_truncate(act);
 306                 entry->sample.rate = tcf_sample_rate(act);
 307                 tcf_offload_sample_get_group(entry, act);
 308                 *index_inc = 1;
 309         } else {
 310                 struct flow_offload_action *fl_action = entry_data;
 311
 312                 fl_action->id = FLOW_ACTION_SAMPLE;
 313         }
 314
 315         return 0;
 316 }
 317
 318 static struct tc_action_ops act_sample_ops = {
 319         .kind     = "sample",
 320         .id       = TCA_ID_SAMPLE,
 321         .owner    = THIS_MODULE,
 322         .act      = tcf_sample_act,
 323         .stats_update = tcf_sample_stats_update,
 324         .dump     = tcf_sample_dump,
 325         .init     = tcf_sample_init,
 326         .cleanup  = tcf_sample_cleanup,
 327         .get_psample_group = tcf_sample_get_group,
 328         .offload_act_setup    = tcf_sample_offload_act_setup,
 329         .size     = sizeof(struct tcf_sample),
 330 };
 331 MODULE_ALIAS_NET_ACT("sample");
 332
 333 static __net_init int sample_init_net(struct net *net)
 334 {
 335         struct tc_action_net *tn = net_generic(net, act_sample_ops.net_id);
 336
 337         return tc_action_net_init(net, tn, &act_sample_ops);
 338 }
 339
 340 static void __net_exit sample_exit_net(struct list_head *net_list)
 341 {
 342         tc_action_net_exit(net_list, act_sample_ops.net_id);
 343 }
 344
 345 static struct pernet_operations sample_net_ops = {
 346         .init = sample_init_net,
 347         .exit_batch = sample_exit_net,
 348         .id   = &act_sample_ops.net_id,
 349         .size = sizeof(struct tc_action_net),
 350 };
 351
 352 static int __init sample_init_module(void)
 353 {
 354         return tcf_register_action(&act_sample_ops, &sample_net_ops);
 355 }
 356
 357 static void __exit sample_cleanup_module(void)
 358 {
 359         tcf_unregister_action(&act_sample_ops, &sample_net_ops);
 360 }
 361
 362 module_init(sample_init_module);
 363 module_exit(sample_cleanup_module);
 364
 365 MODULE_AUTHOR("Yotam Gigi <[email protected]>");
 366 MODULE_DESCRIPTION("Packet sampling action");
 367 MODULE_LICENSE("GPL v2");