net/sched/act_mirred.c

   1 /*
   2  * net/sched/act_mirred.c       packet mirroring and redirect actions
   3  *
   4  *              This program is free software; you can redistribute it and/or
   5  *              modify it under the terms of the GNU General Public License
   6  *              as published by the Free Software Foundation; either version
   7  *              2 of the License, or (at your option) any later version.
   8  *
   9  * Authors:     Jamal Hadi Salim (2002-4)
  10  *
  11  * TODO: Add ingress support (and socket redirect support)
  12  *
  13  */
  14
  15 #include <linux/types.h>
  16 #include <linux/kernel.h>
  17 #include <linux/string.h>
  18 #include <linux/errno.h>
  19 #include <linux/skbuff.h>
  20 #include <linux/rtnetlink.h>
  21 #include <linux/module.h>
  22 #include <linux/init.h>
  23 #include <linux/gfp.h>
  24 #include <net/net_namespace.h>
  25 #include <net/netlink.h>
  26 #include <net/pkt_sched.h>
  27 #include <linux/tc_act/tc_mirred.h>
  28 #include <net/tc_act/tc_mirred.h>
  29
  30 #include <linux/if_arp.h>
  31
  32 #define MIRRED_TAB_MASK     7
  33 static LIST_HEAD(mirred_list);
  34 static DEFINE_SPINLOCK(mirred_list_lock);
  35
  36 static void tcf_mirred_release(struct tc_action *a, int bind)
  37 {
  38         struct tcf_mirred *m = to_mirred(a);
  39         struct net_device *dev;
  40
  41         /* We could be called either in a RCU callback or with RTNL lock held. */
  42         spin_lock_bh(&mirred_list_lock);
  43         list_del(&m->tcfm_list);
  44         dev = rcu_dereference_protected(m->tcfm_dev, 1);
  45         if (dev)
  46                 dev_put(dev);
  47         spin_unlock_bh(&mirred_list_lock);
  48 }
  49
  50 static const struct nla_policy mirred_policy[TCA_MIRRED_MAX + 1] = {
  51         [TCA_MIRRED_PARMS]      = { .len = sizeof(struct tc_mirred) },
  52 };
  53
  54 static int mirred_net_id;
  55 static struct tc_action_ops act_mirred_ops;
  56
  57 static int tcf_mirred_init(struct net *net, struct nlattr *nla,
  58                            struct nlattr *est, struct tc_action **a, int ovr,
  59                            int bind)
  60 {
  61         struct tc_action_net *tn = net_generic(net, mirred_net_id);
  62         struct nlattr *tb[TCA_MIRRED_MAX + 1];
  63         struct tc_mirred *parm;
  64         struct tcf_mirred *m;
  65         struct net_device *dev;
  66         int ret, ok_push = 0;
  67         bool exists = false;
  68
  69         if (nla == NULL)
  70                 return -EINVAL;
  71         ret = nla_parse_nested(tb, TCA_MIRRED_MAX, nla, mirred_policy);
  72         if (ret < 0)
  73                 return ret;
  74         if (tb[TCA_MIRRED_PARMS] == NULL)
  75                 return -EINVAL;
  76         parm = nla_data(tb[TCA_MIRRED_PARMS]);
  77
  78         exists = tcf_hash_check(tn, parm->index, a, bind);
  79         if (exists && bind)
  80                 return 0;
  81
  82         switch (parm->eaction) {
  83         case TCA_EGRESS_MIRROR:
  84         case TCA_EGRESS_REDIR:
  85                 break;
  86         default:
  87                 if (exists)
  88                         tcf_hash_release(*a, bind);
  89                 return -EINVAL;
  90         }
  91         if (parm->ifindex) {
  92                 dev = __dev_get_by_index(net, parm->ifindex);
  93                 if (dev == NULL) {
  94                         if (exists)
  95                                 tcf_hash_release(*a, bind);
  96                         return -ENODEV;
  97                 }
  98                 switch (dev->type) {
  99                 case ARPHRD_TUNNEL:
 100                 case ARPHRD_TUNNEL6:
 101                 case ARPHRD_SIT:
 102                 case ARPHRD_IPGRE:
 103                 case ARPHRD_VOID:
 104                 case ARPHRD_NONE:
 105                         ok_push = 0;
 106                         break;
 107                 default:
 108                         ok_push = 1;
 109                         break;
 110                 }
 111         } else {
 112                 dev = NULL;
 113         }
 114
 115         if (!exists) {
 116                 if (dev == NULL)
 117                         return -EINVAL;
 118                 ret = tcf_hash_create(tn, parm->index, est, a,
 119                                       &act_mirred_ops, bind, true);
 120                 if (ret)
 121                         return ret;
 122                 ret = ACT_P_CREATED;
 123         } else {
 124                 tcf_hash_release(*a, bind);
 125                 if (!ovr)
 126                         return -EEXIST;
 127         }
 128         m = to_mirred(*a);
 129
 130         ASSERT_RTNL();
 131         m->tcf_action = parm->action;
 132         m->tcfm_eaction = parm->eaction;
 133         if (dev != NULL) {
 134                 m->tcfm_ifindex = parm->ifindex;
 135                 if (ret != ACT_P_CREATED)
 136                         dev_put(rcu_dereference_protected(m->tcfm_dev, 1));
 137                 dev_hold(dev);
 138                 rcu_assign_pointer(m->tcfm_dev, dev);
 139                 m->tcfm_ok_push = ok_push;
 140         }
 141
 142         if (ret == ACT_P_CREATED) {
 143                 spin_lock_bh(&mirred_list_lock);
 144                 list_add(&m->tcfm_list, &mirred_list);
 145                 spin_unlock_bh(&mirred_list_lock);
 146                 tcf_hash_insert(tn, *a);
 147         }
 148
 149         return ret;
 150 }
 151
 152 static int tcf_mirred(struct sk_buff *skb, const struct tc_action *a,
 153                       struct tcf_result *res)
 154 {
 155         struct tcf_mirred *m = to_mirred(a);
 156         struct net_device *dev;
 157         struct sk_buff *skb2;
 158         int retval, err;
 159         u32 at;
 160
 161         tcf_lastuse_update(&m->tcf_tm);
 162         bstats_cpu_update(this_cpu_ptr(m->common.cpu_bstats), skb);
 163
 164         rcu_read_lock();
 165         retval = READ_ONCE(m->tcf_action);
 166         dev = rcu_dereference(m->tcfm_dev);
 167         if (unlikely(!dev)) {
 168                 pr_notice_once("tc mirred: target device is gone\n");
 169                 goto out;
 170         }
 171
 172         if (unlikely(!(dev->flags & IFF_UP))) {
 173                 net_notice_ratelimited("tc mirred to Houston: device %s is down\n",
 174                                        dev->name);
 175                 goto out;
 176         }
 177
 178         at = G_TC_AT(skb->tc_verd);
 179         skb2 = skb_clone(skb, GFP_ATOMIC);
 180         if (!skb2)
 181                 goto out;
 182
 183         if (!(at & AT_EGRESS)) {
 184                 if (m->tcfm_ok_push)
 185                         skb_push_rcsum(skb2, skb->mac_len);
 186         }
 187
 188         /* mirror is always swallowed */
 189         if (m->tcfm_eaction != TCA_EGRESS_MIRROR)
 190                 skb2->tc_verd = SET_TC_FROM(skb2->tc_verd, at);
 191
 192         skb2->skb_iif = skb->dev->ifindex;
 193         skb2->dev = dev;
 194         err = dev_queue_xmit(skb2);
 195
 196         if (err) {
 197 out:
 198                 qstats_overlimit_inc(this_cpu_ptr(m->common.cpu_qstats));
 199                 if (m->tcfm_eaction != TCA_EGRESS_MIRROR)
 200                         retval = TC_ACT_SHOT;
 201         }
 202         rcu_read_unlock();
 203
 204         return retval;
 205 }
 206
 207 static void tcf_stats_update(struct tc_action *a, u64 bytes, u32 packets,
 208                              u64 lastuse)
 209 {
 210         tcf_lastuse_update(&a->tcfa_tm);
 211         _bstats_cpu_update(this_cpu_ptr(a->cpu_bstats), bytes, packets);
 212 }
 213
 214 static int tcf_mirred_dump(struct sk_buff *skb, struct tc_action *a, int bind,
 215                            int ref)
 216 {
 217         unsigned char *b = skb_tail_pointer(skb);
 218         struct tcf_mirred *m = to_mirred(a);
 219         struct tc_mirred opt = {
 220                 .index   = m->tcf_index,
 221                 .action  = m->tcf_action,
 222                 .refcnt  = m->tcf_refcnt - ref,
 223                 .bindcnt = m->tcf_bindcnt - bind,
 224                 .eaction = m->tcfm_eaction,
 225                 .ifindex = m->tcfm_ifindex,
 226         };
 227         struct tcf_t t;
 228
 229         if (nla_put(skb, TCA_MIRRED_PARMS, sizeof(opt), &opt))
 230                 goto nla_put_failure;
 231
 232         tcf_tm_dump(&t, &m->tcf_tm);
 233         if (nla_put_64bit(skb, TCA_MIRRED_TM, sizeof(t), &t, TCA_MIRRED_PAD))
 234                 goto nla_put_failure;
 235         return skb->len;
 236
 237 nla_put_failure:
 238         nlmsg_trim(skb, b);
 239         return -1;
 240 }
 241
 242 static int tcf_mirred_walker(struct net *net, struct sk_buff *skb,
 243                              struct netlink_callback *cb, int type,
 244                              const struct tc_action_ops *ops)
 245 {
 246         struct tc_action_net *tn = net_generic(net, mirred_net_id);
 247
 248         return tcf_generic_walker(tn, skb, cb, type, ops);
 249 }
 250
 251 static int tcf_mirred_search(struct net *net, struct tc_action **a, u32 index)
 252 {
 253         struct tc_action_net *tn = net_generic(net, mirred_net_id);
 254
 255         return tcf_hash_search(tn, a, index);
 256 }
 257
 258 static int mirred_device_event(struct notifier_block *unused,
 259                                unsigned long event, void *ptr)
 260 {
 261         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 262         struct tcf_mirred *m;
 263
 264         ASSERT_RTNL();
 265         if (event == NETDEV_UNREGISTER) {
 266                 spin_lock_bh(&mirred_list_lock);
 267                 list_for_each_entry(m, &mirred_list, tcfm_list) {
 268                         if (rcu_access_pointer(m->tcfm_dev) == dev) {
 269                                 dev_put(dev);
 270                                 /* Note : no rcu grace period necessary, as
 271                                  * net_device are already rcu protected.
 272                                  */
 273                                 RCU_INIT_POINTER(m->tcfm_dev, NULL);
 274                         }
 275                 }
 276                 spin_unlock_bh(&mirred_list_lock);
 277         }
 278
 279         return NOTIFY_DONE;
 280 }
 281
 282 static struct notifier_block mirred_device_notifier = {
 283         .notifier_call = mirred_device_event,
 284 };
 285
 286 static struct tc_action_ops act_mirred_ops = {
 287         .kind           =       "mirred",
 288         .type           =       TCA_ACT_MIRRED,
 289         .owner          =       THIS_MODULE,
 290         .act            =       tcf_mirred,
 291         .stats_update   =       tcf_stats_update,
 292         .dump           =       tcf_mirred_dump,
 293         .cleanup        =       tcf_mirred_release,
 294         .init           =       tcf_mirred_init,
 295         .walk           =       tcf_mirred_walker,
 296         .lookup         =       tcf_mirred_search,
 297         .size           =       sizeof(struct tcf_mirred),
 298 };
 299
 300 static __net_init int mirred_init_net(struct net *net)
 301 {
 302         struct tc_action_net *tn = net_generic(net, mirred_net_id);
 303
 304         return tc_action_net_init(tn, &act_mirred_ops, MIRRED_TAB_MASK);
 305 }
 306
 307 static void __net_exit mirred_exit_net(struct net *net)
 308 {
 309         struct tc_action_net *tn = net_generic(net, mirred_net_id);
 310
 311         tc_action_net_exit(tn);
 312 }
 313
 314 static struct pernet_operations mirred_net_ops = {
 315         .init = mirred_init_net,
 316         .exit = mirred_exit_net,
 317         .id   = &mirred_net_id,
 318         .size = sizeof(struct tc_action_net),
 319 };
 320
 321 MODULE_AUTHOR("Jamal Hadi Salim(2002)");
 322 MODULE_DESCRIPTION("Device Mirror/redirect actions");
 323 MODULE_LICENSE("GPL");
 324
 325 static int __init mirred_init_module(void)
 326 {
 327         int err = register_netdevice_notifier(&mirred_device_notifier);
 328         if (err)
 329                 return err;
 330
 331         pr_info("Mirror/redirect action on\n");
 332         return tcf_register_action(&act_mirred_ops, &mirred_net_ops);
 333 }
 334
 335 static void __exit mirred_cleanup_module(void)
 336 {
 337         tcf_unregister_action(&act_mirred_ops, &mirred_net_ops);
 338         unregister_netdevice_notifier(&mirred_device_notifier);
 339 }
 340
 341 module_init(mirred_init_module);
 342 module_exit(mirred_cleanup_module);