net/sched/act_sample.c

   1 /*
   2  * net/sched/act_sample.c - Packet sampling tc action
   3  * Copyright (c) 2017 Yotam Gigi <[email protected]>
   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)
  41 {
  42         struct tc_action_net *tn = net_generic(net, sample_net_id);
  43         struct nlattr *tb[TCA_SAMPLE_MAX + 1];
  44         struct psample_group *psample_group;
  45         struct tc_sample *parm;
  46         struct tcf_sample *s;
  47         bool exists = false;
  48         int ret;
  49
  50         if (!nla)
  51                 return -EINVAL;
  52         ret = nla_parse_nested(tb, TCA_SAMPLE_MAX, nla, sample_policy, NULL);
  53         if (ret < 0)
  54                 return ret;
  55         if (!tb[TCA_SAMPLE_PARMS] || !tb[TCA_SAMPLE_RATE] ||
  56             !tb[TCA_SAMPLE_PSAMPLE_GROUP])
  57                 return -EINVAL;
  58
  59         parm = nla_data(tb[TCA_SAMPLE_PARMS]);
  60
  61         exists = tcf_idr_check(tn, parm->index, a, bind);
  62         if (exists && bind)
  63                 return 0;
  64
  65         if (!exists) {
  66                 ret = tcf_idr_create(tn, parm->index, est, a,
  67                                      &act_sample_ops, bind, false);
  68                 if (ret)
  69                         return ret;
  70                 ret = ACT_P_CREATED;
  71         } else {
  72                 tcf_idr_release(*a, bind);
  73                 if (!ovr)
  74                         return -EEXIST;
  75         }
  76         s = to_sample(*a);
  77
  78         s->tcf_action = parm->action;
  79         s->rate = nla_get_u32(tb[TCA_SAMPLE_RATE]);
  80         s->psample_group_num = nla_get_u32(tb[TCA_SAMPLE_PSAMPLE_GROUP]);
  81         psample_group = psample_group_get(net, s->psample_group_num);
  82         if (!psample_group) {
  83                 if (ret == ACT_P_CREATED)
  84                         tcf_idr_release(*a, bind);
  85                 return -ENOMEM;
  86         }
  87         RCU_INIT_POINTER(s->psample_group, psample_group);
  88
  89         if (tb[TCA_SAMPLE_TRUNC_SIZE]) {
  90                 s->truncate = true;
  91                 s->trunc_size = nla_get_u32(tb[TCA_SAMPLE_TRUNC_SIZE]);
  92         }
  93
  94         if (ret == ACT_P_CREATED)
  95                 tcf_idr_insert(tn, *a);
  96         return ret;
  97 }
  98
  99 static void tcf_sample_cleanup(struct tc_action *a)
 100 {
 101         struct tcf_sample *s = to_sample(a);
 102         struct psample_group *psample_group;
 103
 104         psample_group = rtnl_dereference(s->psample_group);
 105         RCU_INIT_POINTER(s->psample_group, NULL);
 106         psample_group_put(psample_group);
 107 }
 108
 109 static bool tcf_sample_dev_ok_push(struct net_device *dev)
 110 {
 111         switch (dev->type) {
 112         case ARPHRD_TUNNEL:
 113         case ARPHRD_TUNNEL6:
 114         case ARPHRD_SIT:
 115         case ARPHRD_IPGRE:
 116         case ARPHRD_VOID:
 117         case ARPHRD_NONE:
 118                 return false;
 119         default:
 120                 return true;
 121         }
 122 }
 123
 124 static int tcf_sample_act(struct sk_buff *skb, const struct tc_action *a,
 125                           struct tcf_result *res)
 126 {
 127         struct tcf_sample *s = to_sample(a);
 128         struct psample_group *psample_group;
 129         int retval;
 130         int size;
 131         int iif;
 132         int oif;
 133
 134         tcf_lastuse_update(&s->tcf_tm);
 135         bstats_cpu_update(this_cpu_ptr(s->common.cpu_bstats), skb);
 136         retval = READ_ONCE(s->tcf_action);
 137
 138         rcu_read_lock();
 139         psample_group = rcu_dereference(s->psample_group);
 140
 141         /* randomly sample packets according to rate */
 142         if (psample_group && (prandom_u32() % s->rate == 0)) {
 143                 if (!skb_at_tc_ingress(skb)) {
 144                         iif = skb->skb_iif;
 145                         oif = skb->dev->ifindex;
 146                 } else {
 147                         iif = skb->dev->ifindex;
 148                         oif = 0;
 149                 }
 150
 151                 /* on ingress, the mac header gets popped, so push it back */
 152                 if (skb_at_tc_ingress(skb) && tcf_sample_dev_ok_push(skb->dev))
 153                         skb_push(skb, skb->mac_len);
 154
 155                 size = s->truncate ? s->trunc_size : skb->len;
 156                 psample_sample_packet(psample_group, skb, size, iif, oif,
 157                                       s->rate);
 158
 159                 if (skb_at_tc_ingress(skb) && tcf_sample_dev_ok_push(skb->dev))
 160                         skb_pull(skb, skb->mac_len);
 161         }
 162
 163         rcu_read_unlock();
 164         return retval;
 165 }
 166
 167 static int tcf_sample_dump(struct sk_buff *skb, struct tc_action *a,
 168                            int bind, int ref)
 169 {
 170         unsigned char *b = skb_tail_pointer(skb);
 171         struct tcf_sample *s = to_sample(a);
 172         struct tc_sample opt = {
 173                 .index      = s->tcf_index,
 174                 .action     = s->tcf_action,
 175                 .refcnt     = s->tcf_refcnt - ref,
 176                 .bindcnt    = s->tcf_bindcnt - bind,
 177         };
 178         struct tcf_t t;
 179
 180         if (nla_put(skb, TCA_SAMPLE_PARMS, sizeof(opt), &opt))
 181                 goto nla_put_failure;
 182
 183         tcf_tm_dump(&t, &s->tcf_tm);
 184         if (nla_put_64bit(skb, TCA_SAMPLE_TM, sizeof(t), &t, TCA_SAMPLE_PAD))
 185                 goto nla_put_failure;
 186
 187         if (nla_put_u32(skb, TCA_SAMPLE_RATE, s->rate))
 188                 goto nla_put_failure;
 189
 190         if (s->truncate)
 191                 if (nla_put_u32(skb, TCA_SAMPLE_TRUNC_SIZE, s->trunc_size))
 192                         goto nla_put_failure;
 193
 194         if (nla_put_u32(skb, TCA_SAMPLE_PSAMPLE_GROUP, s->psample_group_num))
 195                 goto nla_put_failure;
 196         return skb->len;
 197
 198 nla_put_failure:
 199         nlmsg_trim(skb, b);
 200         return -1;
 201 }
 202
 203 static int tcf_sample_walker(struct net *net, struct sk_buff *skb,
 204                              struct netlink_callback *cb, int type,
 205                              const struct tc_action_ops *ops)
 206 {
 207         struct tc_action_net *tn = net_generic(net, sample_net_id);
 208
 209         return tcf_generic_walker(tn, skb, cb, type, ops);
 210 }
 211
 212 static int tcf_sample_search(struct net *net, struct tc_action **a, u32 index)
 213 {
 214         struct tc_action_net *tn = net_generic(net, sample_net_id);
 215
 216         return tcf_idr_search(tn, a, index);
 217 }
 218
 219 static struct tc_action_ops act_sample_ops = {
 220         .kind     = "sample",
 221         .type     = TCA_ACT_SAMPLE,
 222         .owner    = THIS_MODULE,
 223         .act      = tcf_sample_act,
 224         .dump     = tcf_sample_dump,
 225         .init     = tcf_sample_init,
 226         .cleanup  = tcf_sample_cleanup,
 227         .walk     = tcf_sample_walker,
 228         .lookup   = tcf_sample_search,
 229         .size     = sizeof(struct tcf_sample),
 230 };
 231
 232 static __net_init int sample_init_net(struct net *net)
 233 {
 234         struct tc_action_net *tn = net_generic(net, sample_net_id);
 235
 236         return tc_action_net_init(tn, &act_sample_ops);
 237 }
 238
 239 static void __net_exit sample_exit_net(struct list_head *net_list)
 240 {
 241         tc_action_net_exit(net_list, sample_net_id);
 242 }
 243
 244 static struct pernet_operations sample_net_ops = {
 245         .init = sample_init_net,
 246         .exit_batch = sample_exit_net,
 247         .id   = &sample_net_id,
 248         .size = sizeof(struct tc_action_net),
 249 };
 250
 251 static int __init sample_init_module(void)
 252 {
 253         return tcf_register_action(&act_sample_ops, &sample_net_ops);
 254 }
 255
 256 static void __exit sample_cleanup_module(void)
 257 {
 258         tcf_unregister_action(&act_sample_ops, &sample_net_ops);
 259 }
 260
 261 module_init(sample_init_module);
 262 module_exit(sample_cleanup_module);
 263
 264 MODULE_AUTHOR("Yotam Gigi <[email protected]>");
 265 MODULE_DESCRIPTION("Packet sampling action");
 266 MODULE_LICENSE("GPL v2");