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
  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         if (!tb[TCA_SAMPLE_PARMS] || !tb[TCA_SAMPLE_RATE] ||
  58             !tb[TCA_SAMPLE_PSAMPLE_GROUP])
  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, 0);
  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         err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack);
  83         if (err < 0)
  84                 goto release_idr;
  85
  86         rate = nla_get_u32(tb[TCA_SAMPLE_RATE]);
  87         if (!rate) {
  88                 NL_SET_ERR_MSG(extack, "invalid sample rate");
  89                 err = -EINVAL;
  90                 goto put_chain;
  91         }
  92         psample_group_num = nla_get_u32(tb[TCA_SAMPLE_PSAMPLE_GROUP]);
  93         psample_group = psample_group_get(net, psample_group_num);
  94         if (!psample_group) {
  95                 err = -ENOMEM;
  96                 goto put_chain;
  97         }
  98
  99         s = to_sample(*a);
 100
 101         spin_lock_bh(&s->tcf_lock);
 102         goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
 103         s->rate = rate;
 104         s->psample_group_num = psample_group_num;
 105         psample_group = rcu_replace_pointer(s->psample_group, psample_group,
 106                                             lockdep_is_held(&s->tcf_lock));
 107
 108         if (tb[TCA_SAMPLE_TRUNC_SIZE]) {
 109                 s->truncate = true;
 110                 s->trunc_size = nla_get_u32(tb[TCA_SAMPLE_TRUNC_SIZE]);
 111         }
 112         spin_unlock_bh(&s->tcf_lock);
 113
 114         if (psample_group)
 115                 psample_group_put(psample_group);
 116         if (goto_ch)
 117                 tcf_chain_put_by_act(goto_ch);
 118
 119         return ret;
 120 put_chain:
 121         if (goto_ch)
 122                 tcf_chain_put_by_act(goto_ch);
 123 release_idr:
 124         tcf_idr_release(*a, bind);
 125         return err;
 126 }
 127
 128 static void tcf_sample_cleanup(struct tc_action *a)
 129 {
 130         struct tcf_sample *s = to_sample(a);
 131         struct psample_group *psample_group;
 132
 133         /* last reference to action, no need to lock */
 134         psample_group = rcu_dereference_protected(s->psample_group, 1);
 135         RCU_INIT_POINTER(s->psample_group, NULL);
 136         if (psample_group)
 137                 psample_group_put(psample_group);
 138 }
 139
 140 static bool tcf_sample_dev_ok_push(struct net_device *dev)
 141 {
 142         switch (dev->type) {
 143         case ARPHRD_TUNNEL:
 144         case ARPHRD_TUNNEL6:
 145         case ARPHRD_SIT:
 146         case ARPHRD_IPGRE:
 147         case ARPHRD_IP6GRE:
 148         case ARPHRD_VOID:
 149         case ARPHRD_NONE:
 150                 return false;
 151         default:
 152                 return true;
 153         }
 154 }
 155
 156 static int tcf_sample_act(struct sk_buff *skb, const struct tc_action *a,
 157                           struct tcf_result *res)
 158 {
 159         struct tcf_sample *s = to_sample(a);
 160         struct psample_group *psample_group;
 161         int retval;
 162         int size;
 163         int iif;
 164         int oif;
 165
 166         tcf_lastuse_update(&s->tcf_tm);
 167         bstats_cpu_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 && (prandom_u32() % s->rate == 0)) {
 174                 if (!skb_at_tc_ingress(skb)) {
 175                         iif = skb->skb_iif;
 176                         oif = skb->dev->ifindex;
 177                 } else {
 178                         iif = skb->dev->ifindex;
 179                         oif = 0;
 180                 }
 181
 182                 /* on ingress, the mac header gets popped, so push it back */
 183                 if (skb_at_tc_ingress(skb) && tcf_sample_dev_ok_push(skb->dev))
 184                         skb_push(skb, skb->mac_len);
 185
 186                 size = s->truncate ? s->trunc_size : skb->len;
 187                 psample_sample_packet(psample_group, skb, size, iif, oif,
 188                                       s->rate);
 189
 190                 if (skb_at_tc_ingress(skb) && tcf_sample_dev_ok_push(skb->dev))
 191                         skb_pull(skb, skb->mac_len);
 192         }
 193
 194         return retval;
 195 }
 196
 197 static int tcf_sample_dump(struct sk_buff *skb, struct tc_action *a,
 198                            int bind, int ref)
 199 {
 200         unsigned char *b = skb_tail_pointer(skb);
 201         struct tcf_sample *s = to_sample(a);
 202         struct tc_sample opt = {
 203                 .index      = s->tcf_index,
 204                 .refcnt     = refcount_read(&s->tcf_refcnt) - ref,
 205                 .bindcnt    = atomic_read(&s->tcf_bindcnt) - bind,
 206         };
 207         struct tcf_t t;
 208
 209         spin_lock_bh(&s->tcf_lock);
 210         opt.action = s->tcf_action;
 211         if (nla_put(skb, TCA_SAMPLE_PARMS, sizeof(opt), &opt))
 212                 goto nla_put_failure;
 213
 214         tcf_tm_dump(&t, &s->tcf_tm);
 215         if (nla_put_64bit(skb, TCA_SAMPLE_TM, sizeof(t), &t, TCA_SAMPLE_PAD))
 216                 goto nla_put_failure;
 217
 218         if (nla_put_u32(skb, TCA_SAMPLE_RATE, s->rate))
 219                 goto nla_put_failure;
 220
 221         if (s->truncate)
 222                 if (nla_put_u32(skb, TCA_SAMPLE_TRUNC_SIZE, s->trunc_size))
 223                         goto nla_put_failure;
 224
 225         if (nla_put_u32(skb, TCA_SAMPLE_PSAMPLE_GROUP, s->psample_group_num))
 226                 goto nla_put_failure;
 227         spin_unlock_bh(&s->tcf_lock);
 228
 229         return skb->len;
 230
 231 nla_put_failure:
 232         spin_unlock_bh(&s->tcf_lock);
 233         nlmsg_trim(skb, b);
 234         return -1;
 235 }
 236
 237 static int tcf_sample_walker(struct net *net, struct sk_buff *skb,
 238                              struct netlink_callback *cb, int type,
 239                              const struct tc_action_ops *ops,
 240                              struct netlink_ext_ack *extack)
 241 {
 242         struct tc_action_net *tn = net_generic(net, sample_net_id);
 243
 244         return tcf_generic_walker(tn, skb, cb, type, ops, extack);
 245 }
 246
 247 static int tcf_sample_search(struct net *net, struct tc_action **a, u32 index)
 248 {
 249         struct tc_action_net *tn = net_generic(net, sample_net_id);
 250
 251         return tcf_idr_search(tn, a, index);
 252 }
 253
 254 static void tcf_psample_group_put(void *priv)
 255 {
 256         struct psample_group *group = priv;
 257
 258         psample_group_put(group);
 259 }
 260
 261 static struct psample_group *
 262 tcf_sample_get_group(const struct tc_action *a,
 263                      tc_action_priv_destructor *destructor)
 264 {
 265         struct tcf_sample *s = to_sample(a);
 266         struct psample_group *group;
 267
 268         group = rcu_dereference_protected(s->psample_group,
 269                                           lockdep_is_held(&s->tcf_lock));
 270         if (group) {
 271                 psample_group_take(group);
 272                 *destructor = tcf_psample_group_put;
 273         }
 274
 275         return group;
 276 }
 277
 278 static struct tc_action_ops act_sample_ops = {
 279         .kind     = "sample",
 280         .id       = TCA_ID_SAMPLE,
 281         .owner    = THIS_MODULE,
 282         .act      = tcf_sample_act,
 283         .dump     = tcf_sample_dump,
 284         .init     = tcf_sample_init,
 285         .cleanup  = tcf_sample_cleanup,
 286         .walk     = tcf_sample_walker,
 287         .lookup   = tcf_sample_search,
 288         .get_psample_group = tcf_sample_get_group,
 289         .size     = sizeof(struct tcf_sample),
 290 };
 291
 292 static __net_init int sample_init_net(struct net *net)
 293 {
 294         struct tc_action_net *tn = net_generic(net, sample_net_id);
 295
 296         return tc_action_net_init(net, tn, &act_sample_ops);
 297 }
 298
 299 static void __net_exit sample_exit_net(struct list_head *net_list)
 300 {
 301         tc_action_net_exit(net_list, sample_net_id);
 302 }
 303
 304 static struct pernet_operations sample_net_ops = {
 305         .init = sample_init_net,
 306         .exit_batch = sample_exit_net,
 307         .id   = &sample_net_id,
 308         .size = sizeof(struct tc_action_net),
 309 };
 310
 311 static int __init sample_init_module(void)
 312 {
 313         return tcf_register_action(&act_sample_ops, &sample_net_ops);
 314 }
 315
 316 static void __exit sample_cleanup_module(void)
 317 {
 318         tcf_unregister_action(&act_sample_ops, &sample_net_ops);
 319 }
 320
 321 module_init(sample_init_module);
 322 module_exit(sample_cleanup_module);
 323
 324 MODULE_AUTHOR("Yotam Gigi <[email protected]>");
 325 MODULE_DESCRIPTION("Packet sampling action");
 326 MODULE_LICENSE("GPL v2");