net/sched/act_sample.c

   1 /*
   2  * net/sched/act_sample.c - Packet sampling tc action
   3  * Copyright (c) 2017 Yotam Gigi <yotamg@mellanox.com>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License version 2 as
   7  * published by the Free Software Foundation.
   8  */
   9
  10 #include <linux/types.h>
  11 #include <linux/kernel.h>
  12 #include <linux/string.h>
  13 #include <linux/errno.h>
  14 #include <linux/skbuff.h>
  15 #include <linux/rtnetlink.h>
  16 #include <linux/module.h>
  17 #include <linux/init.h>
  18 #include <linux/gfp.h>
  19 #include <net/net_namespace.h>
  20 #include <net/netlink.h>
  21 #include <net/pkt_sched.h>
  22 #include <linux/tc_act/tc_sample.h>
  23 #include <net/tc_act/tc_sample.h>
  24 #include <net/psample.h>
  25 #include <net/pkt_cls.h>
  26
  27 #include <linux/if_arp.h>
  28
  29 static unsigned int sample_net_id;
  30 static struct tc_action_ops act_sample_ops;
  31
  32 static const struct nla_policy sample_policy[TCA_SAMPLE_MAX + 1] = {
  33         [TCA_SAMPLE_PARMS]              = { .len = sizeof(struct tc_sample) },
  34         [TCA_SAMPLE_RATE]               = { .type = NLA_U32 },
  35         [TCA_SAMPLE_TRUNC_SIZE]         = { .type = NLA_U32 },
  36         [TCA_SAMPLE_PSAMPLE_GROUP]      = { .type = NLA_U32 },
  37 };
  38
  39 static int tcf_sample_init(struct net *net, struct nlattr *nla,
  40                            struct nlattr *est, struct tc_action **a, int ovr,
  41                            int bind, bool rtnl_held, struct tcf_proto *tp,
  42                            struct netlink_ext_ack *extack)
  43 {
  44         struct tc_action_net *tn = net_generic(net, sample_net_id);
  45         struct nlattr *tb[TCA_SAMPLE_MAX + 1];
  46         struct psample_group *psample_group;
  47         struct tcf_chain *goto_ch = NULL;
  48         u32 psample_group_num, rate;
  49         struct tc_sample *parm;
  50         struct tcf_sample *s;
  51         bool exists = false;
  52         int ret, err;
  53
  54         if (!nla)
  55                 return -EINVAL;
  56         ret = nla_parse_nested_deprecated(tb, TCA_SAMPLE_MAX, nla,
  57                                           sample_policy, NULL);
  58         if (ret < 0)
  59                 return ret;
  60         if (!tb[TCA_SAMPLE_PARMS] || !tb[TCA_SAMPLE_RATE] ||
  61             !tb[TCA_SAMPLE_PSAMPLE_GROUP])
  62                 return -EINVAL;
  63
  64         parm = nla_data(tb[TCA_SAMPLE_PARMS]);
  65
  66         err = tcf_idr_check_alloc(tn, &parm->index, a, bind);
  67         if (err < 0)
  68                 return err;
  69         exists = err;
  70         if (exists && bind)
  71                 return 0;
  72
  73         if (!exists) {
  74                 ret = tcf_idr_create(tn, parm->index, est, a,
  75                                      &act_sample_ops, bind, true);
  76                 if (ret) {
  77                         tcf_idr_cleanup(tn, parm->index);
  78                         return ret;
  79                 }
  80                 ret = ACT_P_CREATED;
  81         } else if (!ovr) {
  82                 tcf_idr_release(*a, bind);
  83                 return -EEXIST;
  84         }
  85         err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack);
  86         if (err < 0)
  87                 goto release_idr;
  88
  89         rate = nla_get_u32(tb[TCA_SAMPLE_RATE]);
  90         if (!rate) {
  91                 NL_SET_ERR_MSG(extack, "invalid sample rate");
  92                 err = -EINVAL;
  93                 goto put_chain;
  94         }
  95         psample_group_num = nla_get_u32(tb[TCA_SAMPLE_PSAMPLE_GROUP]);
  96         psample_group = psample_group_get(net, psample_group_num);
  97         if (!psample_group) {
  98                 err = -ENOMEM;
  99                 goto put_chain;
 100         }
 101
 102         s = to_sample(*a);
 103
 104         spin_lock_bh(&s->tcf_lock);
 105         goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
 106         s->rate = rate;
 107         s->psample_group_num = psample_group_num;
 108         RCU_INIT_POINTER(s->psample_group, psample_group);
 109
 110         if (tb[TCA_SAMPLE_TRUNC_SIZE]) {
 111                 s->truncate = true;
 112                 s->trunc_size = nla_get_u32(tb[TCA_SAMPLE_TRUNC_SIZE]);
 113         }
 114         spin_unlock_bh(&s->tcf_lock);
 115         if (goto_ch)
 116                 tcf_chain_put_by_act(goto_ch);
 117
 118         if (ret == ACT_P_CREATED)
 119                 tcf_idr_insert(tn, *a);
 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_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 struct tc_action_ops act_sample_ops = {
 255         .kind     = "sample",
 256         .id       = TCA_ID_SAMPLE,
 257         .owner    = THIS_MODULE,
 258         .act      = tcf_sample_act,
 259         .dump     = tcf_sample_dump,
 260         .init     = tcf_sample_init,
 261         .cleanup  = tcf_sample_cleanup,
 262         .walk     = tcf_sample_walker,
 263         .lookup   = tcf_sample_search,
 264         .size     = sizeof(struct tcf_sample),
 265 };
 266
 267 static __net_init int sample_init_net(struct net *net)
 268 {
 269         struct tc_action_net *tn = net_generic(net, sample_net_id);
 270
 271         return tc_action_net_init(tn, &act_sample_ops);
 272 }
 273
 274 static void __net_exit sample_exit_net(struct list_head *net_list)
 275 {
 276         tc_action_net_exit(net_list, sample_net_id);
 277 }
 278
 279 static struct pernet_operations sample_net_ops = {
 280         .init = sample_init_net,
 281         .exit_batch = sample_exit_net,
 282         .id   = &sample_net_id,
 283         .size = sizeof(struct tc_action_net),
 284 };
 285
 286 static int __init sample_init_module(void)
 287 {
 288         return tcf_register_action(&act_sample_ops, &sample_net_ops);
 289 }
 290
 291 static void __exit sample_cleanup_module(void)
 292 {
 293         tcf_unregister_action(&act_sample_ops, &sample_net_ops);
 294 }
 295
 296 module_init(sample_init_module);
 297 module_exit(sample_cleanup_module);
 298
 299 MODULE_AUTHOR("Yotam Gigi <yotam.gi@gmail.com>");
 300 MODULE_DESCRIPTION("Packet sampling action");
 301 MODULE_LICENSE("GPL v2");