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
  26 #include <linux/if_arp.h>
  27
  28 static unsigned int sample_net_id;
  29 static struct tc_action_ops act_sample_ops;
  30
  31 static const struct nla_policy sample_policy[TCA_SAMPLE_MAX + 1] = {
  32         [TCA_SAMPLE_PARMS]              = { .len = sizeof(struct tc_sample) },
  33         [TCA_SAMPLE_RATE]               = { .type = NLA_U32 },
  34         [TCA_SAMPLE_TRUNC_SIZE]         = { .type = NLA_U32 },
  35         [TCA_SAMPLE_PSAMPLE_GROUP]      = { .type = NLA_U32 },
  36 };
  37
  38 static int tcf_sample_init(struct net *net, struct nlattr *nla,
  39                            struct nlattr *est, struct tc_action **a, int ovr,
  40                            int bind, bool rtnl_held,
  41                            struct netlink_ext_ack *extack)
  42 {
  43         struct tc_action_net *tn = net_generic(net, sample_net_id);
  44         struct nlattr *tb[TCA_SAMPLE_MAX + 1];
  45         struct psample_group *psample_group;
  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(tb, TCA_SAMPLE_MAX, nla, sample_policy, NULL);
  54         if (ret < 0)
  55                 return ret;
  56         if (!tb[TCA_SAMPLE_PARMS] || !tb[TCA_SAMPLE_RATE] ||
  57             !tb[TCA_SAMPLE_PSAMPLE_GROUP])
  58                 return -EINVAL;
  59
  60         parm = nla_data(tb[TCA_SAMPLE_PARMS]);
  61
  62         err = tcf_idr_check_alloc(tn, &parm->index, a, bind);
  63         if (err < 0)
  64                 return err;
  65         exists = err;
  66         if (exists && bind)
  67                 return 0;
  68
  69         if (!exists) {
  70                 ret = tcf_idr_create(tn, parm->index, est, a,
  71                                      &act_sample_ops, bind, false);
  72                 if (ret) {
  73                         tcf_idr_cleanup(tn, parm->index);
  74                         return ret;
  75                 }
  76                 ret = ACT_P_CREATED;
  77         } else if (!ovr) {
  78                 tcf_idr_release(*a, bind);
  79                 return -EEXIST;
  80         }
  81         s = to_sample(*a);
  82
  83         s->tcf_action = parm->action;
  84         s->rate = nla_get_u32(tb[TCA_SAMPLE_RATE]);
  85         s->psample_group_num = nla_get_u32(tb[TCA_SAMPLE_PSAMPLE_GROUP]);
  86         psample_group = psample_group_get(net, s->psample_group_num);
  87         if (!psample_group) {
  88                 tcf_idr_release(*a, bind);
  89                 return -ENOMEM;
  90         }
  91         RCU_INIT_POINTER(s->psample_group, psample_group);
  92
  93         if (tb[TCA_SAMPLE_TRUNC_SIZE]) {
  94                 s->truncate = true;
  95                 s->trunc_size = nla_get_u32(tb[TCA_SAMPLE_TRUNC_SIZE]);
  96         }
  97
  98         if (ret == ACT_P_CREATED)
  99                 tcf_idr_insert(tn, *a);
 100         return ret;
 101 }
 102
 103 static void tcf_sample_cleanup(struct tc_action *a)
 104 {
 105         struct tcf_sample *s = to_sample(a);
 106         struct psample_group *psample_group;
 107
 108         psample_group = rtnl_dereference(s->psample_group);
 109         RCU_INIT_POINTER(s->psample_group, NULL);
 110         if (psample_group)
 111                 psample_group_put(psample_group);
 112 }
 113
 114 static bool tcf_sample_dev_ok_push(struct net_device *dev)
 115 {
 116         switch (dev->type) {
 117         case ARPHRD_TUNNEL:
 118         case ARPHRD_TUNNEL6:
 119         case ARPHRD_SIT:
 120         case ARPHRD_IPGRE:
 121         case ARPHRD_VOID:
 122         case ARPHRD_NONE:
 123                 return false;
 124         default:
 125                 return true;
 126         }
 127 }
 128
 129 static int tcf_sample_act(struct sk_buff *skb, const struct tc_action *a,
 130                           struct tcf_result *res)
 131 {
 132         struct tcf_sample *s = to_sample(a);
 133         struct psample_group *psample_group;
 134         int retval;
 135         int size;
 136         int iif;
 137         int oif;
 138
 139         tcf_lastuse_update(&s->tcf_tm);
 140         bstats_cpu_update(this_cpu_ptr(s->common.cpu_bstats), skb);
 141         retval = READ_ONCE(s->tcf_action);
 142
 143         rcu_read_lock();
 144         psample_group = rcu_dereference(s->psample_group);
 145
 146         /* randomly sample packets according to rate */
 147         if (psample_group && (prandom_u32() % s->rate == 0)) {
 148                 if (!skb_at_tc_ingress(skb)) {
 149                         iif = skb->skb_iif;
 150                         oif = skb->dev->ifindex;
 151                 } else {
 152                         iif = skb->dev->ifindex;
 153                         oif = 0;
 154                 }
 155
 156                 /* on ingress, the mac header gets popped, so push it back */
 157                 if (skb_at_tc_ingress(skb) && tcf_sample_dev_ok_push(skb->dev))
 158                         skb_push(skb, skb->mac_len);
 159
 160                 size = s->truncate ? s->trunc_size : skb->len;
 161                 psample_sample_packet(psample_group, skb, size, iif, oif,
 162                                       s->rate);
 163
 164                 if (skb_at_tc_ingress(skb) && tcf_sample_dev_ok_push(skb->dev))
 165                         skb_pull(skb, skb->mac_len);
 166         }
 167
 168         rcu_read_unlock();
 169         return retval;
 170 }
 171
 172 static int tcf_sample_dump(struct sk_buff *skb, struct tc_action *a,
 173                            int bind, int ref)
 174 {
 175         unsigned char *b = skb_tail_pointer(skb);
 176         struct tcf_sample *s = to_sample(a);
 177         struct tc_sample opt = {
 178                 .index      = s->tcf_index,
 179                 .action     = s->tcf_action,
 180                 .refcnt     = refcount_read(&s->tcf_refcnt) - ref,
 181                 .bindcnt    = atomic_read(&s->tcf_bindcnt) - bind,
 182         };
 183         struct tcf_t t;
 184
 185         if (nla_put(skb, TCA_SAMPLE_PARMS, sizeof(opt), &opt))
 186                 goto nla_put_failure;
 187
 188         tcf_tm_dump(&t, &s->tcf_tm);
 189         if (nla_put_64bit(skb, TCA_SAMPLE_TM, sizeof(t), &t, TCA_SAMPLE_PAD))
 190                 goto nla_put_failure;
 191
 192         if (nla_put_u32(skb, TCA_SAMPLE_RATE, s->rate))
 193                 goto nla_put_failure;
 194
 195         if (s->truncate)
 196                 if (nla_put_u32(skb, TCA_SAMPLE_TRUNC_SIZE, s->trunc_size))
 197                         goto nla_put_failure;
 198
 199         if (nla_put_u32(skb, TCA_SAMPLE_PSAMPLE_GROUP, s->psample_group_num))
 200                 goto nla_put_failure;
 201         return skb->len;
 202
 203 nla_put_failure:
 204         nlmsg_trim(skb, b);
 205         return -1;
 206 }
 207
 208 static int tcf_sample_walker(struct net *net, struct sk_buff *skb,
 209                              struct netlink_callback *cb, int type,
 210                              const struct tc_action_ops *ops,
 211                              struct netlink_ext_ack *extack)
 212 {
 213         struct tc_action_net *tn = net_generic(net, sample_net_id);
 214
 215         return tcf_generic_walker(tn, skb, cb, type, ops, extack);
 216 }
 217
 218 static int tcf_sample_search(struct net *net, struct tc_action **a, u32 index,
 219                              struct netlink_ext_ack *extack)
 220 {
 221         struct tc_action_net *tn = net_generic(net, sample_net_id);
 222
 223         return tcf_idr_search(tn, a, index);
 224 }
 225
 226 static int tcf_sample_delete(struct net *net, u32 index)
 227 {
 228         struct tc_action_net *tn = net_generic(net, sample_net_id);
 229
 230         return tcf_idr_delete_index(tn, index);
 231 }
 232
 233 static struct tc_action_ops act_sample_ops = {
 234         .kind     = "sample",
 235         .type     = TCA_ACT_SAMPLE,
 236         .owner    = THIS_MODULE,
 237         .act      = tcf_sample_act,
 238         .dump     = tcf_sample_dump,
 239         .init     = tcf_sample_init,
 240         .cleanup  = tcf_sample_cleanup,
 241         .walk     = tcf_sample_walker,
 242         .lookup   = tcf_sample_search,
 243         .delete   = tcf_sample_delete,
 244         .size     = sizeof(struct tcf_sample),
 245 };
 246
 247 static __net_init int sample_init_net(struct net *net)
 248 {
 249         struct tc_action_net *tn = net_generic(net, sample_net_id);
 250
 251         return tc_action_net_init(tn, &act_sample_ops);
 252 }
 253
 254 static void __net_exit sample_exit_net(struct list_head *net_list)
 255 {
 256         tc_action_net_exit(net_list, sample_net_id);
 257 }
 258
 259 static struct pernet_operations sample_net_ops = {
 260         .init = sample_init_net,
 261         .exit_batch = sample_exit_net,
 262         .id   = &sample_net_id,
 263         .size = sizeof(struct tc_action_net),
 264 };
 265
 266 static int __init sample_init_module(void)
 267 {
 268         return tcf_register_action(&act_sample_ops, &sample_net_ops);
 269 }
 270
 271 static void __exit sample_cleanup_module(void)
 272 {
 273         tcf_unregister_action(&act_sample_ops, &sample_net_ops);
 274 }
 275
 276 module_init(sample_init_module);
 277 module_exit(sample_cleanup_module);
 278
 279 MODULE_AUTHOR("Yotam Gigi <yotam.gi@gmail.com>");
 280 MODULE_DESCRIPTION("Packet sampling action");
 281 MODULE_LICENSE("GPL v2");