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 <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,
  38                            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         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, 0);
  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 static int tcf_sample_act(struct sk_buff *skb, const struct tc_action *a,
 158                           struct tcf_result *res)
 159 {
 160         struct tcf_sample *s = to_sample(a);
 161         struct psample_group *psample_group;
 162         struct psample_metadata md = {};
 163         int retval;
 164
 165         tcf_lastuse_update(&s->tcf_tm);
 166         bstats_cpu_update(this_cpu_ptr(s->common.cpu_bstats), skb);
 167         retval = READ_ONCE(s->tcf_action);
 168
 169         psample_group = rcu_dereference_bh(s->psample_group);
 170
 171         /* randomly sample packets according to rate */
 172         if (psample_group && (prandom_u32() % s->rate == 0)) {
 173                 if (!skb_at_tc_ingress(skb)) {
 174                         md.in_ifindex = skb->skb_iif;
 175                         md.out_ifindex = skb->dev->ifindex;
 176                 } else {
 177                         md.in_ifindex = skb->dev->ifindex;
 178                 }
 179
 180                 /* on ingress, the mac header gets popped, so push it back */
 181                 if (skb_at_tc_ingress(skb) && tcf_sample_dev_ok_push(skb->dev))
 182                         skb_push(skb, skb->mac_len);
 183
 184                 md.trunc_size = s->truncate ? s->trunc_size : skb->len;
 185                 psample_sample_packet(psample_group, skb, s->rate, &md);
 186
 187                 if (skb_at_tc_ingress(skb) && tcf_sample_dev_ok_push(skb->dev))
 188                         skb_pull(skb, skb->mac_len);
 189         }
 190
 191         return retval;
 192 }
 193
 194 static void tcf_sample_stats_update(struct tc_action *a, u64 bytes, u64 packets,
 195                                     u64 drops, u64 lastuse, bool hw)
 196 {
 197         struct tcf_sample *s = to_sample(a);
 198         struct tcf_t *tm = &s->tcf_tm;
 199
 200         tcf_action_update_stats(a, bytes, packets, drops, hw);
 201         tm->lastuse = max_t(u64, tm->lastuse, lastuse);
 202 }
 203
 204 static int tcf_sample_dump(struct sk_buff *skb, struct tc_action *a,
 205                            int bind, int ref)
 206 {
 207         unsigned char *b = skb_tail_pointer(skb);
 208         struct tcf_sample *s = to_sample(a);
 209         struct tc_sample opt = {
 210                 .index      = s->tcf_index,
 211                 .refcnt     = refcount_read(&s->tcf_refcnt) - ref,
 212                 .bindcnt    = atomic_read(&s->tcf_bindcnt) - bind,
 213         };
 214         struct tcf_t t;
 215
 216         spin_lock_bh(&s->tcf_lock);
 217         opt.action = s->tcf_action;
 218         if (nla_put(skb, TCA_SAMPLE_PARMS, sizeof(opt), &opt))
 219                 goto nla_put_failure;
 220
 221         tcf_tm_dump(&t, &s->tcf_tm);
 222         if (nla_put_64bit(skb, TCA_SAMPLE_TM, sizeof(t), &t, TCA_SAMPLE_PAD))
 223                 goto nla_put_failure;
 224
 225         if (nla_put_u32(skb, TCA_SAMPLE_RATE, s->rate))
 226                 goto nla_put_failure;
 227
 228         if (s->truncate)
 229                 if (nla_put_u32(skb, TCA_SAMPLE_TRUNC_SIZE, s->trunc_size))
 230                         goto nla_put_failure;
 231
 232         if (nla_put_u32(skb, TCA_SAMPLE_PSAMPLE_GROUP, s->psample_group_num))
 233                 goto nla_put_failure;
 234         spin_unlock_bh(&s->tcf_lock);
 235
 236         return skb->len;
 237
 238 nla_put_failure:
 239         spin_unlock_bh(&s->tcf_lock);
 240         nlmsg_trim(skb, b);
 241         return -1;
 242 }
 243
 244 static int tcf_sample_walker(struct net *net, struct sk_buff *skb,
 245                              struct netlink_callback *cb, int type,
 246                              const struct tc_action_ops *ops,
 247                              struct netlink_ext_ack *extack)
 248 {
 249         struct tc_action_net *tn = net_generic(net, sample_net_id);
 250
 251         return tcf_generic_walker(tn, skb, cb, type, ops, extack);
 252 }
 253
 254 static int tcf_sample_search(struct net *net, struct tc_action **a, u32 index)
 255 {
 256         struct tc_action_net *tn = net_generic(net, sample_net_id);
 257
 258         return tcf_idr_search(tn, a, index);
 259 }
 260
 261 static void tcf_psample_group_put(void *priv)
 262 {
 263         struct psample_group *group = priv;
 264
 265         psample_group_put(group);
 266 }
 267
 268 static struct psample_group *
 269 tcf_sample_get_group(const struct tc_action *a,
 270                      tc_action_priv_destructor *destructor)
 271 {
 272         struct tcf_sample *s = to_sample(a);
 273         struct psample_group *group;
 274
 275         group = rcu_dereference_protected(s->psample_group,
 276                                           lockdep_is_held(&s->tcf_lock));
 277         if (group) {
 278                 psample_group_take(group);
 279                 *destructor = tcf_psample_group_put;
 280         }
 281
 282         return group;
 283 }
 284
 285 static struct tc_action_ops act_sample_ops = {
 286         .kind     = "sample",
 287         .id       = TCA_ID_SAMPLE,
 288         .owner    = THIS_MODULE,
 289         .act      = tcf_sample_act,
 290         .stats_update = tcf_sample_stats_update,
 291         .dump     = tcf_sample_dump,
 292         .init     = tcf_sample_init,
 293         .cleanup  = tcf_sample_cleanup,
 294         .walk     = tcf_sample_walker,
 295         .lookup   = tcf_sample_search,
 296         .get_psample_group = tcf_sample_get_group,
 297         .size     = sizeof(struct tcf_sample),
 298 };
 299
 300 static __net_init int sample_init_net(struct net *net)
 301 {
 302         struct tc_action_net *tn = net_generic(net, sample_net_id);
 303
 304         return tc_action_net_init(net, tn, &act_sample_ops);
 305 }
 306
 307 static void __net_exit sample_exit_net(struct list_head *net_list)
 308 {
 309         tc_action_net_exit(net_list, sample_net_id);
 310 }
 311
 312 static struct pernet_operations sample_net_ops = {
 313         .init = sample_init_net,
 314         .exit_batch = sample_exit_net,
 315         .id   = &sample_net_id,
 316         .size = sizeof(struct tc_action_net),
 317 };
 318
 319 static int __init sample_init_module(void)
 320 {
 321         return tcf_register_action(&act_sample_ops, &sample_net_ops);
 322 }
 323
 324 static void __exit sample_cleanup_module(void)
 325 {
 326         tcf_unregister_action(&act_sample_ops, &sample_net_ops);
 327 }
 328
 329 module_init(sample_init_module);
 330 module_exit(sample_cleanup_module);
 331
 332 MODULE_AUTHOR("Yotam Gigi <yotam.gi@gmail.com>");
 333 MODULE_DESCRIPTION("Packet sampling action");
 334 MODULE_LICENSE("GPL v2");