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         struct tc_sample *parm;
  49         u32 psample_group_num;
  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(tb, TCA_SAMPLE_MAX, nla, sample_policy, NULL);
  57         if (ret < 0)
  58                 return ret;
  59         if (!tb[TCA_SAMPLE_PARMS] || !tb[TCA_SAMPLE_RATE] ||
  60             !tb[TCA_SAMPLE_PSAMPLE_GROUP])
  61                 return -EINVAL;
  62
  63         parm = nla_data(tb[TCA_SAMPLE_PARMS]);
  64
  65         err = tcf_idr_check_alloc(tn, &parm->index, a, bind);
  66         if (err < 0)
  67                 return err;
  68         exists = err;
  69         if (exists && bind)
  70                 return 0;
  71
  72         if (!exists) {
  73                 ret = tcf_idr_create(tn, parm->index, est, a,
  74                                      &act_sample_ops, bind, true);
  75                 if (ret) {
  76                         tcf_idr_cleanup(tn, parm->index);
  77                         return ret;
  78                 }
  79                 ret = ACT_P_CREATED;
  80         } else if (!ovr) {
  81                 tcf_idr_release(*a, bind);
  82                 return -EEXIST;
  83         }
  84         err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack);
  85         if (err < 0)
  86                 goto release_idr;
  87
  88         psample_group_num = nla_get_u32(tb[TCA_SAMPLE_PSAMPLE_GROUP]);
  89         psample_group = psample_group_get(net, psample_group_num);
  90         if (!psample_group) {
  91                 err = -ENOMEM;
  92                 goto put_chain;
  93         }
  94
  95         s = to_sample(*a);
  96
  97         spin_lock_bh(&s->tcf_lock);
  98         goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
  99         s->rate = nla_get_u32(tb[TCA_SAMPLE_RATE]);
 100         s->psample_group_num = psample_group_num;
 101         RCU_INIT_POINTER(s->psample_group, psample_group);
 102
 103         if (tb[TCA_SAMPLE_TRUNC_SIZE]) {
 104                 s->truncate = true;
 105                 s->trunc_size = nla_get_u32(tb[TCA_SAMPLE_TRUNC_SIZE]);
 106         }
 107         spin_unlock_bh(&s->tcf_lock);
 108         if (goto_ch)
 109                 tcf_chain_put_by_act(goto_ch);
 110
 111         if (ret == ACT_P_CREATED)
 112                 tcf_idr_insert(tn, *a);
 113         return ret;
 114 put_chain:
 115         if (goto_ch)
 116                 tcf_chain_put_by_act(goto_ch);
 117 release_idr:
 118         tcf_idr_release(*a, bind);
 119         return err;
 120 }
 121
 122 static void tcf_sample_cleanup(struct tc_action *a)
 123 {
 124         struct tcf_sample *s = to_sample(a);
 125         struct psample_group *psample_group;
 126
 127         /* last reference to action, no need to lock */
 128         psample_group = rcu_dereference_protected(s->psample_group, 1);
 129         RCU_INIT_POINTER(s->psample_group, NULL);
 130         if (psample_group)
 131                 psample_group_put(psample_group);
 132 }
 133
 134 static bool tcf_sample_dev_ok_push(struct net_device *dev)
 135 {
 136         switch (dev->type) {
 137         case ARPHRD_TUNNEL:
 138         case ARPHRD_TUNNEL6:
 139         case ARPHRD_SIT:
 140         case ARPHRD_IPGRE:
 141         case ARPHRD_VOID:
 142         case ARPHRD_NONE:
 143                 return false;
 144         default:
 145                 return true;
 146         }
 147 }
 148
 149 static int tcf_sample_act(struct sk_buff *skb, const struct tc_action *a,
 150                           struct tcf_result *res)
 151 {
 152         struct tcf_sample *s = to_sample(a);
 153         struct psample_group *psample_group;
 154         int retval;
 155         int size;
 156         int iif;
 157         int oif;
 158
 159         tcf_lastuse_update(&s->tcf_tm);
 160         bstats_cpu_update(this_cpu_ptr(s->common.cpu_bstats), skb);
 161         retval = READ_ONCE(s->tcf_action);
 162
 163         psample_group = rcu_dereference_bh(s->psample_group);
 164
 165         /* randomly sample packets according to rate */
 166         if (psample_group && (prandom_u32() % s->rate == 0)) {
 167                 if (!skb_at_tc_ingress(skb)) {
 168                         iif = skb->skb_iif;
 169                         oif = skb->dev->ifindex;
 170                 } else {
 171                         iif = skb->dev->ifindex;
 172                         oif = 0;
 173                 }
 174
 175                 /* on ingress, the mac header gets popped, so push it back */
 176                 if (skb_at_tc_ingress(skb) && tcf_sample_dev_ok_push(skb->dev))
 177                         skb_push(skb, skb->mac_len);
 178
 179                 size = s->truncate ? s->trunc_size : skb->len;
 180                 psample_sample_packet(psample_group, skb, size, iif, oif,
 181                                       s->rate);
 182
 183                 if (skb_at_tc_ingress(skb) && tcf_sample_dev_ok_push(skb->dev))
 184                         skb_pull(skb, skb->mac_len);
 185         }
 186
 187         return retval;
 188 }
 189
 190 static int tcf_sample_dump(struct sk_buff *skb, struct tc_action *a,
 191                            int bind, int ref)
 192 {
 193         unsigned char *b = skb_tail_pointer(skb);
 194         struct tcf_sample *s = to_sample(a);
 195         struct tc_sample opt = {
 196                 .index      = s->tcf_index,
 197                 .refcnt     = refcount_read(&s->tcf_refcnt) - ref,
 198                 .bindcnt    = atomic_read(&s->tcf_bindcnt) - bind,
 199         };
 200         struct tcf_t t;
 201
 202         spin_lock_bh(&s->tcf_lock);
 203         opt.action = s->tcf_action;
 204         if (nla_put(skb, TCA_SAMPLE_PARMS, sizeof(opt), &opt))
 205                 goto nla_put_failure;
 206
 207         tcf_tm_dump(&t, &s->tcf_tm);
 208         if (nla_put_64bit(skb, TCA_SAMPLE_TM, sizeof(t), &t, TCA_SAMPLE_PAD))
 209                 goto nla_put_failure;
 210
 211         if (nla_put_u32(skb, TCA_SAMPLE_RATE, s->rate))
 212                 goto nla_put_failure;
 213
 214         if (s->truncate)
 215                 if (nla_put_u32(skb, TCA_SAMPLE_TRUNC_SIZE, s->trunc_size))
 216                         goto nla_put_failure;
 217
 218         if (nla_put_u32(skb, TCA_SAMPLE_PSAMPLE_GROUP, s->psample_group_num))
 219                 goto nla_put_failure;
 220         spin_unlock_bh(&s->tcf_lock);
 221
 222         return skb->len;
 223
 224 nla_put_failure:
 225         spin_unlock_bh(&s->tcf_lock);
 226         nlmsg_trim(skb, b);
 227         return -1;
 228 }
 229
 230 static int tcf_sample_walker(struct net *net, struct sk_buff *skb,
 231                              struct netlink_callback *cb, int type,
 232                              const struct tc_action_ops *ops,
 233                              struct netlink_ext_ack *extack)
 234 {
 235         struct tc_action_net *tn = net_generic(net, sample_net_id);
 236
 237         return tcf_generic_walker(tn, skb, cb, type, ops, extack);
 238 }
 239
 240 static int tcf_sample_search(struct net *net, struct tc_action **a, u32 index)
 241 {
 242         struct tc_action_net *tn = net_generic(net, sample_net_id);
 243
 244         return tcf_idr_search(tn, a, index);
 245 }
 246
 247 static struct tc_action_ops act_sample_ops = {
 248         .kind     = "sample",
 249         .id       = TCA_ID_SAMPLE,
 250         .owner    = THIS_MODULE,
 251         .act      = tcf_sample_act,
 252         .dump     = tcf_sample_dump,
 253         .init     = tcf_sample_init,
 254         .cleanup  = tcf_sample_cleanup,
 255         .walk     = tcf_sample_walker,
 256         .lookup   = tcf_sample_search,
 257         .size     = sizeof(struct tcf_sample),
 258 };
 259
 260 static __net_init int sample_init_net(struct net *net)
 261 {
 262         struct tc_action_net *tn = net_generic(net, sample_net_id);
 263
 264         return tc_action_net_init(tn, &act_sample_ops);
 265 }
 266
 267 static void __net_exit sample_exit_net(struct list_head *net_list)
 268 {
 269         tc_action_net_exit(net_list, sample_net_id);
 270 }
 271
 272 static struct pernet_operations sample_net_ops = {
 273         .init = sample_init_net,
 274         .exit_batch = sample_exit_net,
 275         .id   = &sample_net_id,
 276         .size = sizeof(struct tc_action_net),
 277 };
 278
 279 static int __init sample_init_module(void)
 280 {
 281         return tcf_register_action(&act_sample_ops, &sample_net_ops);
 282 }
 283
 284 static void __exit sample_cleanup_module(void)
 285 {
 286         tcf_unregister_action(&act_sample_ops, &sample_net_ops);
 287 }
 288
 289 module_init(sample_init_module);
 290 module_exit(sample_cleanup_module);
 291
 292 MODULE_AUTHOR("Yotam Gigi <yotam.gi@gmail.com>");
 293 MODULE_DESCRIPTION("Packet sampling action");
 294 MODULE_LICENSE("GPL v2");