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, 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
  58         if (!tb[TCA_SAMPLE_PARMS])
  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, flags);
  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
  83         if (!tb[TCA_SAMPLE_RATE] || !tb[TCA_SAMPLE_PSAMPLE_GROUP]) {
  84                 NL_SET_ERR_MSG(extack, "sample rate and group are required");
  85                 err = -EINVAL;
  86                 goto release_idr;
  87         }
  88
  89         err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack);
  90         if (err < 0)
  91                 goto release_idr;
  92
  93         rate = nla_get_u32(tb[TCA_SAMPLE_RATE]);
  94         if (!rate) {
  95                 NL_SET_ERR_MSG(extack, "invalid sample rate");
  96                 err = -EINVAL;
  97                 goto put_chain;
  98         }
  99         psample_group_num = nla_get_u32(tb[TCA_SAMPLE_PSAMPLE_GROUP]);
 100         psample_group = psample_group_get(net, psample_group_num);
 101         if (!psample_group) {
 102                 err = -ENOMEM;
 103                 goto put_chain;
 104         }
 105
 106         s = to_sample(*a);
 107
 108         spin_lock_bh(&s->tcf_lock);
 109         goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
 110         s->rate = rate;
 111         s->psample_group_num = psample_group_num;
 112         psample_group = rcu_replace_pointer(s->psample_group, psample_group,
 113                                             lockdep_is_held(&s->tcf_lock));
 114
 115         if (tb[TCA_SAMPLE_TRUNC_SIZE]) {
 116                 s->truncate = true;
 117                 s->trunc_size = nla_get_u32(tb[TCA_SAMPLE_TRUNC_SIZE]);
 118         }
 119         spin_unlock_bh(&s->tcf_lock);
 120
 121         if (psample_group)
 122                 psample_group_put(psample_group);
 123         if (goto_ch)
 124                 tcf_chain_put_by_act(goto_ch);
 125
 126         return ret;
 127 put_chain:
 128         if (goto_ch)
 129                 tcf_chain_put_by_act(goto_ch);
 130 release_idr:
 131         tcf_idr_release(*a, bind);
 132         return err;
 133 }
 134
 135 static void tcf_sample_cleanup(struct tc_action *a)
 136 {
 137         struct tcf_sample *s = to_sample(a);
 138         struct psample_group *psample_group;
 139
 140         /* last reference to action, no need to lock */
 141         psample_group = rcu_dereference_protected(s->psample_group, 1);
 142         RCU_INIT_POINTER(s->psample_group, NULL);
 143         if (psample_group)
 144                 psample_group_put(psample_group);
 145 }
 146
 147 static bool tcf_sample_dev_ok_push(struct net_device *dev)
 148 {
 149         switch (dev->type) {
 150         case ARPHRD_TUNNEL:
 151         case ARPHRD_TUNNEL6:
 152         case ARPHRD_SIT:
 153         case ARPHRD_IPGRE:
 154         case ARPHRD_IP6GRE:
 155         case ARPHRD_VOID:
 156         case ARPHRD_NONE:
 157                 return false;
 158         default:
 159                 return true;
 160         }
 161 }
 162
 163 static int tcf_sample_act(struct sk_buff *skb, const struct tc_action *a,
 164                           struct tcf_result *res)
 165 {
 166         struct tcf_sample *s = to_sample(a);
 167         struct psample_group *psample_group;
 168         int retval;
 169         int size;
 170         int iif;
 171         int oif;
 172
 173         tcf_lastuse_update(&s->tcf_tm);
 174         bstats_cpu_update(this_cpu_ptr(s->common.cpu_bstats), skb);
 175         retval = READ_ONCE(s->tcf_action);
 176
 177         psample_group = rcu_dereference_bh(s->psample_group);
 178
 179         /* randomly sample packets according to rate */
 180         if (psample_group && (prandom_u32() % s->rate == 0)) {
 181                 if (!skb_at_tc_ingress(skb)) {
 182                         iif = skb->skb_iif;
 183                         oif = skb->dev->ifindex;
 184                 } else {
 185                         iif = skb->dev->ifindex;
 186                         oif = 0;
 187                 }
 188
 189                 /* on ingress, the mac header gets popped, so push it back */
 190                 if (skb_at_tc_ingress(skb) && tcf_sample_dev_ok_push(skb->dev))
 191                         skb_push(skb, skb->mac_len);
 192
 193                 size = s->truncate ? s->trunc_size : skb->len;
 194                 psample_sample_packet(psample_group, skb, size, iif, oif,
 195                                       s->rate);
 196
 197                 if (skb_at_tc_ingress(skb) && tcf_sample_dev_ok_push(skb->dev))
 198                         skb_pull(skb, skb->mac_len);
 199         }
 200
 201         return retval;
 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         .dump     = tcf_sample_dump,
 291         .init     = tcf_sample_init,
 292         .cleanup  = tcf_sample_cleanup,
 293         .walk     = tcf_sample_walker,
 294         .lookup   = tcf_sample_search,
 295         .get_psample_group = tcf_sample_get_group,
 296         .size     = sizeof(struct tcf_sample),
 297 };
 298
 299 static __net_init int sample_init_net(struct net *net)
 300 {
 301         struct tc_action_net *tn = net_generic(net, sample_net_id);
 302
 303         return tc_action_net_init(net, tn, &act_sample_ops);
 304 }
 305
 306 static void __net_exit sample_exit_net(struct list_head *net_list)
 307 {
 308         tc_action_net_exit(net_list, sample_net_id);
 309 }
 310
 311 static struct pernet_operations sample_net_ops = {
 312         .init = sample_init_net,
 313         .exit_batch = sample_exit_net,
 314         .id   = &sample_net_id,
 315         .size = sizeof(struct tc_action_net),
 316 };
 317
 318 static int __init sample_init_module(void)
 319 {
 320         return tcf_register_action(&act_sample_ops, &sample_net_ops);
 321 }
 322
 323 static void __exit sample_cleanup_module(void)
 324 {
 325         tcf_unregister_action(&act_sample_ops, &sample_net_ops);
 326 }
 327
 328 module_init(sample_init_module);
 329 module_exit(sample_cleanup_module);
 330
 331 MODULE_AUTHOR("Yotam Gigi <yotam.gi@gmail.com>");
 332 MODULE_DESCRIPTION("Packet sampling action");
 333 MODULE_LICENSE("GPL v2");