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         if (!tb[TCA_SAMPLE_PARMS] || !tb[TCA_SAMPLE_RATE] ||
  59             !tb[TCA_SAMPLE_PSAMPLE_GROUP])
  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 0;
  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         err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack);
  84         if (err < 0)
  85                 goto release_idr;
  86
  87         rate = nla_get_u32(tb[TCA_SAMPLE_RATE]);
  88         if (!rate) {
  89                 NL_SET_ERR_MSG(extack, "invalid sample rate");
  90                 err = -EINVAL;
  91                 goto put_chain;
  92         }
  93         psample_group_num = nla_get_u32(tb[TCA_SAMPLE_PSAMPLE_GROUP]);
  94         psample_group = psample_group_get(net, psample_group_num);
  95         if (!psample_group) {
  96                 err = -ENOMEM;
  97                 goto put_chain;
  98         }
  99
 100         s = to_sample(*a);
 101
 102         spin_lock_bh(&s->tcf_lock);
 103         goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
 104         s->rate = rate;
 105         s->psample_group_num = psample_group_num;
 106         psample_group = rcu_replace_pointer(s->psample_group, psample_group,
 107                                             lockdep_is_held(&s->tcf_lock));
 108
 109         if (tb[TCA_SAMPLE_TRUNC_SIZE]) {
 110                 s->truncate = true;
 111                 s->trunc_size = nla_get_u32(tb[TCA_SAMPLE_TRUNC_SIZE]);
 112         }
 113         spin_unlock_bh(&s->tcf_lock);
 114
 115         if (psample_group)
 116                 psample_group_put(psample_group);
 117         if (goto_ch)
 118                 tcf_chain_put_by_act(goto_ch);
 119
 120         return ret;
 121 put_chain:
 122         if (goto_ch)
 123                 tcf_chain_put_by_act(goto_ch);
 124 release_idr:
 125         tcf_idr_release(*a, bind);
 126         return err;
 127 }
 128
 129 static void tcf_sample_cleanup(struct tc_action *a)
 130 {
 131         struct tcf_sample *s = to_sample(a);
 132         struct psample_group *psample_group;
 133
 134         /* last reference to action, no need to lock */
 135         psample_group = rcu_dereference_protected(s->psample_group, 1);
 136         RCU_INIT_POINTER(s->psample_group, NULL);
 137         if (psample_group)
 138                 psample_group_put(psample_group);
 139 }
 140
 141 static bool tcf_sample_dev_ok_push(struct net_device *dev)
 142 {
 143         switch (dev->type) {
 144         case ARPHRD_TUNNEL:
 145         case ARPHRD_TUNNEL6:
 146         case ARPHRD_SIT:
 147         case ARPHRD_IPGRE:
 148         case ARPHRD_IP6GRE:
 149         case ARPHRD_VOID:
 150         case ARPHRD_NONE:
 151                 return false;
 152         default:
 153                 return true;
 154         }
 155 }
 156
 157 TC_INDIRECT_SCOPE int tcf_sample_act(struct sk_buff *skb,
 158                                      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         struct psample_metadata md = {};
 164         int retval;
 165
 166         tcf_lastuse_update(&s->tcf_tm);
 167         bstats_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 && (get_random_u32_below(s->rate) == 0)) {
 174                 if (!skb_at_tc_ingress(skb)) {
 175                         md.in_ifindex = skb->skb_iif;
 176                         md.out_ifindex = skb->dev->ifindex;
 177                 } else {
 178                         md.in_ifindex = skb->dev->ifindex;
 179                 }
 180
 181                 /* on ingress, the mac header gets popped, so push it back */
 182                 if (skb_at_tc_ingress(skb) && tcf_sample_dev_ok_push(skb->dev))
 183                         skb_push(skb, skb->mac_len);
 184
 185                 md.trunc_size = s->truncate ? s->trunc_size : skb->len;
 186                 psample_sample_packet(psample_group, skb, s->rate, &md);
 187
 188                 if (skb_at_tc_ingress(skb) && tcf_sample_dev_ok_push(skb->dev))
 189                         skb_pull(skb, skb->mac_len);
 190         }
 191
 192         return retval;
 193 }
 194
 195 static void tcf_sample_stats_update(struct tc_action *a, u64 bytes, u64 packets,
 196                                     u64 drops, u64 lastuse, bool hw)
 197 {
 198         struct tcf_sample *s = to_sample(a);
 199         struct tcf_t *tm = &s->tcf_tm;
 200
 201         tcf_action_update_stats(a, bytes, packets, drops, hw);
 202         tm->lastuse = max_t(u64, tm->lastuse, lastuse);
 203 }
 204
 205 static int tcf_sample_dump(struct sk_buff *skb, struct tc_action *a,
 206                            int bind, int ref)
 207 {
 208         unsigned char *b = skb_tail_pointer(skb);
 209         struct tcf_sample *s = to_sample(a);
 210         struct tc_sample opt = {
 211                 .index      = s->tcf_index,
 212                 .refcnt     = refcount_read(&s->tcf_refcnt) - ref,
 213                 .bindcnt    = atomic_read(&s->tcf_bindcnt) - bind,
 214         };
 215         struct tcf_t t;
 216
 217         spin_lock_bh(&s->tcf_lock);
 218         opt.action = s->tcf_action;
 219         if (nla_put(skb, TCA_SAMPLE_PARMS, sizeof(opt), &opt))
 220                 goto nla_put_failure;
 221
 222         tcf_tm_dump(&t, &s->tcf_tm);
 223         if (nla_put_64bit(skb, TCA_SAMPLE_TM, sizeof(t), &t, TCA_SAMPLE_PAD))
 224                 goto nla_put_failure;
 225
 226         if (nla_put_u32(skb, TCA_SAMPLE_RATE, s->rate))
 227                 goto nla_put_failure;
 228
 229         if (s->truncate)
 230                 if (nla_put_u32(skb, TCA_SAMPLE_TRUNC_SIZE, s->trunc_size))
 231                         goto nla_put_failure;
 232
 233         if (nla_put_u32(skb, TCA_SAMPLE_PSAMPLE_GROUP, s->psample_group_num))
 234                 goto nla_put_failure;
 235         spin_unlock_bh(&s->tcf_lock);
 236
 237         return skb->len;
 238
 239 nla_put_failure:
 240         spin_unlock_bh(&s->tcf_lock);
 241         nlmsg_trim(skb, b);
 242         return -1;
 243 }
 244
 245 static void tcf_psample_group_put(void *priv)
 246 {
 247         struct psample_group *group = priv;
 248
 249         psample_group_put(group);
 250 }
 251
 252 static struct psample_group *
 253 tcf_sample_get_group(const struct tc_action *a,
 254                      tc_action_priv_destructor *destructor)
 255 {
 256         struct tcf_sample *s = to_sample(a);
 257         struct psample_group *group;
 258
 259         group = rcu_dereference_protected(s->psample_group,
 260                                           lockdep_is_held(&s->tcf_lock));
 261         if (group) {
 262                 psample_group_take(group);
 263                 *destructor = tcf_psample_group_put;
 264         }
 265
 266         return group;
 267 }
 268
 269 static void tcf_offload_sample_get_group(struct flow_action_entry *entry,
 270                                          const struct tc_action *act)
 271 {
 272         entry->sample.psample_group =
 273                 act->ops->get_psample_group(act, &entry->destructor);
 274         entry->destructor_priv = entry->sample.psample_group;
 275 }
 276
 277 static int tcf_sample_offload_act_setup(struct tc_action *act, void *entry_data,
 278                                         u32 *index_inc, bool bind,
 279                                         struct netlink_ext_ack *extack)
 280 {
 281         if (bind) {
 282                 struct flow_action_entry *entry = entry_data;
 283
 284                 entry->id = FLOW_ACTION_SAMPLE;
 285                 entry->sample.trunc_size = tcf_sample_trunc_size(act);
 286                 entry->sample.truncate = tcf_sample_truncate(act);
 287                 entry->sample.rate = tcf_sample_rate(act);
 288                 tcf_offload_sample_get_group(entry, act);
 289                 *index_inc = 1;
 290         } else {
 291                 struct flow_offload_action *fl_action = entry_data;
 292
 293                 fl_action->id = FLOW_ACTION_SAMPLE;
 294         }
 295
 296         return 0;
 297 }
 298
 299 static struct tc_action_ops act_sample_ops = {
 300         .kind     = "sample",
 301         .id       = TCA_ID_SAMPLE,
 302         .owner    = THIS_MODULE,
 303         .act      = tcf_sample_act,
 304         .stats_update = tcf_sample_stats_update,
 305         .dump     = tcf_sample_dump,
 306         .init     = tcf_sample_init,
 307         .cleanup  = tcf_sample_cleanup,
 308         .get_psample_group = tcf_sample_get_group,
 309         .offload_act_setup    = tcf_sample_offload_act_setup,
 310         .size     = sizeof(struct tcf_sample),
 311 };
 312
 313 static __net_init int sample_init_net(struct net *net)
 314 {
 315         struct tc_action_net *tn = net_generic(net, act_sample_ops.net_id);
 316
 317         return tc_action_net_init(net, tn, &act_sample_ops);
 318 }
 319
 320 static void __net_exit sample_exit_net(struct list_head *net_list)
 321 {
 322         tc_action_net_exit(net_list, act_sample_ops.net_id);
 323 }
 324
 325 static struct pernet_operations sample_net_ops = {
 326         .init = sample_init_net,
 327         .exit_batch = sample_exit_net,
 328         .id   = &act_sample_ops.net_id,
 329         .size = sizeof(struct tc_action_net),
 330 };
 331
 332 static int __init sample_init_module(void)
 333 {
 334         return tcf_register_action(&act_sample_ops, &sample_net_ops);
 335 }
 336
 337 static void __exit sample_cleanup_module(void)
 338 {
 339         tcf_unregister_action(&act_sample_ops, &sample_net_ops);
 340 }
 341
 342 module_init(sample_init_module);
 343 module_exit(sample_cleanup_module);
 344
 345 MODULE_AUTHOR("Yotam Gigi <[email protected]>");
 346 MODULE_DESCRIPTION("Packet sampling action");
 347 MODULE_LICENSE("GPL v2");