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         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         if (ret == ACT_P_CREATED)
 120                 tcf_idr_insert(tn, *a);
 121         return ret;
 122 put_chain:
 123         if (goto_ch)
 124                 tcf_chain_put_by_act(goto_ch);
 125 release_idr:
 126         tcf_idr_release(*a, bind);
 127         return err;
 128 }
 129
 130 static void tcf_sample_cleanup(struct tc_action *a)
 131 {
 132         struct tcf_sample *s = to_sample(a);
 133         struct psample_group *psample_group;
 134
 135         /* last reference to action, no need to lock */
 136         psample_group = rcu_dereference_protected(s->psample_group, 1);
 137         RCU_INIT_POINTER(s->psample_group, NULL);
 138         if (psample_group)
 139                 psample_group_put(psample_group);
 140 }
 141
 142 static bool tcf_sample_dev_ok_push(struct net_device *dev)
 143 {
 144         switch (dev->type) {
 145         case ARPHRD_TUNNEL:
 146         case ARPHRD_TUNNEL6:
 147         case ARPHRD_SIT:
 148         case ARPHRD_IPGRE:
 149         case ARPHRD_IP6GRE:
 150         case ARPHRD_VOID:
 151         case ARPHRD_NONE:
 152                 return false;
 153         default:
 154                 return true;
 155         }
 156 }
 157
 158 static int tcf_sample_act(struct sk_buff *skb, 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         int retval;
 164         int size;
 165         int iif;
 166         int oif;
 167
 168         tcf_lastuse_update(&s->tcf_tm);
 169         bstats_cpu_update(this_cpu_ptr(s->common.cpu_bstats), skb);
 170         retval = READ_ONCE(s->tcf_action);
 171
 172         psample_group = rcu_dereference_bh(s->psample_group);
 173
 174         /* randomly sample packets according to rate */
 175         if (psample_group && (prandom_u32() % s->rate == 0)) {
 176                 if (!skb_at_tc_ingress(skb)) {
 177                         iif = skb->skb_iif;
 178                         oif = skb->dev->ifindex;
 179                 } else {
 180                         iif = skb->dev->ifindex;
 181                         oif = 0;
 182                 }
 183
 184                 /* on ingress, the mac header gets popped, so push it back */
 185                 if (skb_at_tc_ingress(skb) && tcf_sample_dev_ok_push(skb->dev))
 186                         skb_push(skb, skb->mac_len);
 187
 188                 size = s->truncate ? s->trunc_size : skb->len;
 189                 psample_sample_packet(psample_group, skb, size, iif, oif,
 190                                       s->rate);
 191
 192                 if (skb_at_tc_ingress(skb) && tcf_sample_dev_ok_push(skb->dev))
 193                         skb_pull(skb, skb->mac_len);
 194         }
 195
 196         return retval;
 197 }
 198
 199 static int tcf_sample_dump(struct sk_buff *skb, struct tc_action *a,
 200                            int bind, int ref)
 201 {
 202         unsigned char *b = skb_tail_pointer(skb);
 203         struct tcf_sample *s = to_sample(a);
 204         struct tc_sample opt = {
 205                 .index      = s->tcf_index,
 206                 .refcnt     = refcount_read(&s->tcf_refcnt) - ref,
 207                 .bindcnt    = atomic_read(&s->tcf_bindcnt) - bind,
 208         };
 209         struct tcf_t t;
 210
 211         spin_lock_bh(&s->tcf_lock);
 212         opt.action = s->tcf_action;
 213         if (nla_put(skb, TCA_SAMPLE_PARMS, sizeof(opt), &opt))
 214                 goto nla_put_failure;
 215
 216         tcf_tm_dump(&t, &s->tcf_tm);
 217         if (nla_put_64bit(skb, TCA_SAMPLE_TM, sizeof(t), &t, TCA_SAMPLE_PAD))
 218                 goto nla_put_failure;
 219
 220         if (nla_put_u32(skb, TCA_SAMPLE_RATE, s->rate))
 221                 goto nla_put_failure;
 222
 223         if (s->truncate)
 224                 if (nla_put_u32(skb, TCA_SAMPLE_TRUNC_SIZE, s->trunc_size))
 225                         goto nla_put_failure;
 226
 227         if (nla_put_u32(skb, TCA_SAMPLE_PSAMPLE_GROUP, s->psample_group_num))
 228                 goto nla_put_failure;
 229         spin_unlock_bh(&s->tcf_lock);
 230
 231         return skb->len;
 232
 233 nla_put_failure:
 234         spin_unlock_bh(&s->tcf_lock);
 235         nlmsg_trim(skb, b);
 236         return -1;
 237 }
 238
 239 static int tcf_sample_walker(struct net *net, struct sk_buff *skb,
 240                              struct netlink_callback *cb, int type,
 241                              const struct tc_action_ops *ops,
 242                              struct netlink_ext_ack *extack)
 243 {
 244         struct tc_action_net *tn = net_generic(net, sample_net_id);
 245
 246         return tcf_generic_walker(tn, skb, cb, type, ops, extack);
 247 }
 248
 249 static int tcf_sample_search(struct net *net, struct tc_action **a, u32 index)
 250 {
 251         struct tc_action_net *tn = net_generic(net, sample_net_id);
 252
 253         return tcf_idr_search(tn, a, index);
 254 }
 255
 256 static void tcf_psample_group_put(void *priv)
 257 {
 258         struct psample_group *group = priv;
 259
 260         psample_group_put(group);
 261 }
 262
 263 static struct psample_group *
 264 tcf_sample_get_group(const struct tc_action *a,
 265                      tc_action_priv_destructor *destructor)
 266 {
 267         struct tcf_sample *s = to_sample(a);
 268         struct psample_group *group;
 269
 270         group = rcu_dereference_protected(s->psample_group,
 271                                           lockdep_is_held(&s->tcf_lock));
 272         if (group) {
 273                 psample_group_take(group);
 274                 *destructor = tcf_psample_group_put;
 275         }
 276
 277         return group;
 278 }
 279
 280 static struct tc_action_ops act_sample_ops = {
 281         .kind     = "sample",
 282         .id       = TCA_ID_SAMPLE,
 283         .owner    = THIS_MODULE,
 284         .act      = tcf_sample_act,
 285         .dump     = tcf_sample_dump,
 286         .init     = tcf_sample_init,
 287         .cleanup  = tcf_sample_cleanup,
 288         .walk     = tcf_sample_walker,
 289         .lookup   = tcf_sample_search,
 290         .get_psample_group = tcf_sample_get_group,
 291         .size     = sizeof(struct tcf_sample),
 292 };
 293
 294 static __net_init int sample_init_net(struct net *net)
 295 {
 296         struct tc_action_net *tn = net_generic(net, sample_net_id);
 297
 298         return tc_action_net_init(net, tn, &act_sample_ops);
 299 }
 300
 301 static void __net_exit sample_exit_net(struct list_head *net_list)
 302 {
 303         tc_action_net_exit(net_list, sample_net_id);
 304 }
 305
 306 static struct pernet_operations sample_net_ops = {
 307         .init = sample_init_net,
 308         .exit_batch = sample_exit_net,
 309         .id   = &sample_net_id,
 310         .size = sizeof(struct tc_action_net),
 311 };
 312
 313 static int __init sample_init_module(void)
 314 {
 315         return tcf_register_action(&act_sample_ops, &sample_net_ops);
 316 }
 317
 318 static void __exit sample_cleanup_module(void)
 319 {
 320         tcf_unregister_action(&act_sample_ops, &sample_net_ops);
 321 }
 322
 323 module_init(sample_init_module);
 324 module_exit(sample_cleanup_module);
 325
 326 MODULE_AUTHOR("Yotam Gigi <yotam.gi@gmail.com>");
 327 MODULE_DESCRIPTION("Packet sampling action");
 328 MODULE_LICENSE("GPL v2");