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 <linux/if_arp.h>
  25 #include <net/net_namespace.h>
  26 #include <net/netlink.h>
  27 #include <net/pkt_sched.h>
  28 #include <net/pkt_cls.h>
  29 #include <linux/tc_act/tc_mirred.h>
  30 #include <net/tc_act/tc_mirred.h>
  31
  32 static LIST_HEAD(mirred_list);
  33 static DEFINE_SPINLOCK(mirred_list_lock);
  34
  35 static bool tcf_mirred_is_act_redirect(int action)
  36 {
  37         return action == TCA_EGRESS_REDIR || action == TCA_INGRESS_REDIR;
  38 }
  39
  40 static bool tcf_mirred_act_wants_ingress(int action)
  41 {
  42         switch (action) {
  43         case TCA_EGRESS_REDIR:
  44         case TCA_EGRESS_MIRROR:
  45                 return false;
  46         case TCA_INGRESS_REDIR:
  47         case TCA_INGRESS_MIRROR:
  48                 return true;
  49         default:
  50                 BUG();
  51         }
  52 }
  53
  54 static bool tcf_mirred_can_reinsert(int action)
  55 {
  56         switch (action) {
  57         case TC_ACT_SHOT:
  58         case TC_ACT_STOLEN:
  59         case TC_ACT_QUEUED:
  60         case TC_ACT_TRAP:
  61                 return true;
  62         }
  63         return false;
  64 }
  65
  66 static struct net_device *tcf_mirred_dev_dereference(struct tcf_mirred *m)
  67 {
  68         return rcu_dereference_protected(m->tcfm_dev,
  69                                          lockdep_is_held(&m->tcf_lock));
  70 }
  71
  72 static void tcf_mirred_release(struct tc_action *a)
  73 {
  74         struct tcf_mirred *m = to_mirred(a);
  75         struct net_device *dev;
  76
  77         spin_lock(&mirred_list_lock);
  78         list_del(&m->tcfm_list);
  79         spin_unlock(&mirred_list_lock);
  80
  81         /* last reference to action, no need to lock */
  82         dev = rcu_dereference_protected(m->tcfm_dev, 1);
  83         if (dev)
  84                 dev_put(dev);
  85 }
  86
  87 static const struct nla_policy mirred_policy[TCA_MIRRED_MAX + 1] = {
  88         [TCA_MIRRED_PARMS]      = { .len = sizeof(struct tc_mirred) },
  89 };
  90
  91 static unsigned int mirred_net_id;
  92 static struct tc_action_ops act_mirred_ops;
  93
  94 static int tcf_mirred_init(struct net *net, struct nlattr *nla,
  95                            struct nlattr *est, struct tc_action **a,
  96                            int ovr, int bind, bool rtnl_held,
  97                            struct tcf_proto *tp,
  98                            struct netlink_ext_ack *extack)
  99 {
 100         struct tc_action_net *tn = net_generic(net, mirred_net_id);
 101         struct nlattr *tb[TCA_MIRRED_MAX + 1];
 102         struct tcf_chain *goto_ch = NULL;
 103         bool mac_header_xmit = false;
 104         struct tc_mirred *parm;
 105         struct tcf_mirred *m;
 106         struct net_device *dev;
 107         bool exists = false;
 108         int ret, err;
 109
 110         if (!nla) {
 111                 NL_SET_ERR_MSG_MOD(extack, "Mirred requires attributes to be passed");
 112                 return -EINVAL;
 113         }
 114         ret = nla_parse_nested(tb, TCA_MIRRED_MAX, nla, mirred_policy, extack);
 115         if (ret < 0)
 116                 return ret;
 117         if (!tb[TCA_MIRRED_PARMS]) {
 118                 NL_SET_ERR_MSG_MOD(extack, "Missing required mirred parameters");
 119                 return -EINVAL;
 120         }
 121         parm = nla_data(tb[TCA_MIRRED_PARMS]);
 122
 123         err = tcf_idr_check_alloc(tn, &parm->index, a, bind);
 124         if (err < 0)
 125                 return err;
 126         exists = err;
 127         if (exists && bind)
 128                 return 0;
 129
 130         switch (parm->eaction) {
 131         case TCA_EGRESS_MIRROR:
 132         case TCA_EGRESS_REDIR:
 133         case TCA_INGRESS_REDIR:
 134         case TCA_INGRESS_MIRROR:
 135                 break;
 136         default:
 137                 if (exists)
 138                         tcf_idr_release(*a, bind);
 139                 else
 140                         tcf_idr_cleanup(tn, parm->index);
 141                 NL_SET_ERR_MSG_MOD(extack, "Unknown mirred option");
 142                 return -EINVAL;
 143         }
 144
 145         if (!exists) {
 146                 if (!parm->ifindex) {
 147                         tcf_idr_cleanup(tn, parm->index);
 148                         NL_SET_ERR_MSG_MOD(extack, "Specified device does not exist");
 149                         return -EINVAL;
 150                 }
 151                 ret = tcf_idr_create(tn, parm->index, est, a,
 152                                      &act_mirred_ops, bind, true);
 153                 if (ret) {
 154                         tcf_idr_cleanup(tn, parm->index);
 155                         return ret;
 156                 }
 157                 ret = ACT_P_CREATED;
 158         } else if (!ovr) {
 159                 tcf_idr_release(*a, bind);
 160                 return -EEXIST;
 161         }
 162
 163         m = to_mirred(*a);
 164         if (ret == ACT_P_CREATED)
 165                 INIT_LIST_HEAD(&m->tcfm_list);
 166
 167         err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack);
 168         if (err < 0)
 169                 goto release_idr;
 170
 171         spin_lock_bh(&m->tcf_lock);
 172
 173         if (parm->ifindex) {
 174                 dev = dev_get_by_index(net, parm->ifindex);
 175                 if (!dev) {
 176                         spin_unlock_bh(&m->tcf_lock);
 177                         err = -ENODEV;
 178                         goto put_chain;
 179                 }
 180                 mac_header_xmit = dev_is_mac_header_xmit(dev);
 181                 rcu_swap_protected(m->tcfm_dev, dev,
 182                                    lockdep_is_held(&m->tcf_lock));
 183                 if (dev)
 184                         dev_put(dev);
 185                 m->tcfm_mac_header_xmit = mac_header_xmit;
 186         }
 187         goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
 188         m->tcfm_eaction = parm->eaction;
 189         spin_unlock_bh(&m->tcf_lock);
 190         if (goto_ch)
 191                 tcf_chain_put_by_act(goto_ch);
 192
 193         if (ret == ACT_P_CREATED) {
 194                 spin_lock(&mirred_list_lock);
 195                 list_add(&m->tcfm_list, &mirred_list);
 196                 spin_unlock(&mirred_list_lock);
 197
 198                 tcf_idr_insert(tn, *a);
 199         }
 200
 201         return ret;
 202 put_chain:
 203         if (goto_ch)
 204                 tcf_chain_put_by_act(goto_ch);
 205 release_idr:
 206         tcf_idr_release(*a, bind);
 207         return err;
 208 }
 209
 210 static int tcf_mirred_act(struct sk_buff *skb, const struct tc_action *a,
 211                           struct tcf_result *res)
 212 {
 213         struct tcf_mirred *m = to_mirred(a);
 214         struct sk_buff *skb2 = skb;
 215         bool m_mac_header_xmit;
 216         struct net_device *dev;
 217         int retval, err = 0;
 218         bool use_reinsert;
 219         bool want_ingress;
 220         bool is_redirect;
 221         int m_eaction;
 222         int mac_len;
 223
 224         tcf_lastuse_update(&m->tcf_tm);
 225         bstats_cpu_update(this_cpu_ptr(m->common.cpu_bstats), skb);
 226
 227         m_mac_header_xmit = READ_ONCE(m->tcfm_mac_header_xmit);
 228         m_eaction = READ_ONCE(m->tcfm_eaction);
 229         retval = READ_ONCE(m->tcf_action);
 230         dev = rcu_dereference_bh(m->tcfm_dev);
 231         if (unlikely(!dev)) {
 232                 pr_notice_once("tc mirred: target device is gone\n");
 233                 goto out;
 234         }
 235
 236         if (unlikely(!(dev->flags & IFF_UP))) {
 237                 net_notice_ratelimited("tc mirred to Houston: device %s is down\n",
 238                                        dev->name);
 239                 goto out;
 240         }
 241
 242         /* we could easily avoid the clone only if called by ingress and clsact;
 243          * since we can't easily detect the clsact caller, skip clone only for
 244          * ingress - that covers the TC S/W datapath.
 245          */
 246         is_redirect = tcf_mirred_is_act_redirect(m_eaction);
 247         use_reinsert = skb_at_tc_ingress(skb) && is_redirect &&
 248                        tcf_mirred_can_reinsert(retval);
 249         if (!use_reinsert) {
 250                 skb2 = skb_clone(skb, GFP_ATOMIC);
 251                 if (!skb2)
 252                         goto out;
 253         }
 254
 255         /* If action's target direction differs than filter's direction,
 256          * and devices expect a mac header on xmit, then mac push/pull is
 257          * needed.
 258          */
 259         want_ingress = tcf_mirred_act_wants_ingress(m_eaction);
 260         if (skb_at_tc_ingress(skb) != want_ingress && m_mac_header_xmit) {
 261                 if (!skb_at_tc_ingress(skb)) {
 262                         /* caught at egress, act ingress: pull mac */
 263                         mac_len = skb_network_header(skb) - skb_mac_header(skb);
 264                         skb_pull_rcsum(skb2, mac_len);
 265                 } else {
 266                         /* caught at ingress, act egress: push mac */
 267                         skb_push_rcsum(skb2, skb->mac_len);
 268                 }
 269         }
 270
 271         skb2->skb_iif = skb->dev->ifindex;
 272         skb2->dev = dev;
 273
 274         /* mirror is always swallowed */
 275         if (is_redirect) {
 276                 skb2->tc_redirected = 1;
 277                 skb2->tc_from_ingress = skb2->tc_at_ingress;
 278                 if (skb2->tc_from_ingress)
 279                         skb2->tstamp = 0;
 280                 /* let's the caller reinsert the packet, if possible */
 281                 if (use_reinsert) {
 282                         res->ingress = want_ingress;
 283                         res->qstats = this_cpu_ptr(m->common.cpu_qstats);
 284                         return TC_ACT_REINSERT;
 285                 }
 286         }
 287
 288         if (!want_ingress)
 289                 err = dev_queue_xmit(skb2);
 290         else
 291                 err = netif_receive_skb(skb2);
 292
 293         if (err) {
 294 out:
 295                 qstats_overlimit_inc(this_cpu_ptr(m->common.cpu_qstats));
 296                 if (tcf_mirred_is_act_redirect(m_eaction))
 297                         retval = TC_ACT_SHOT;
 298         }
 299
 300         return retval;
 301 }
 302
 303 static void tcf_stats_update(struct tc_action *a, u64 bytes, u32 packets,
 304                              u64 lastuse, bool hw)
 305 {
 306         struct tcf_mirred *m = to_mirred(a);
 307         struct tcf_t *tm = &m->tcf_tm;
 308
 309         _bstats_cpu_update(this_cpu_ptr(a->cpu_bstats), bytes, packets);
 310         if (hw)
 311                 _bstats_cpu_update(this_cpu_ptr(a->cpu_bstats_hw),
 312                                    bytes, packets);
 313         tm->lastuse = max_t(u64, tm->lastuse, lastuse);
 314 }
 315
 316 static int tcf_mirred_dump(struct sk_buff *skb, struct tc_action *a, int bind,
 317                            int ref)
 318 {
 319         unsigned char *b = skb_tail_pointer(skb);
 320         struct tcf_mirred *m = to_mirred(a);
 321         struct tc_mirred opt = {
 322                 .index   = m->tcf_index,
 323                 .refcnt  = refcount_read(&m->tcf_refcnt) - ref,
 324                 .bindcnt = atomic_read(&m->tcf_bindcnt) - bind,
 325         };
 326         struct net_device *dev;
 327         struct tcf_t t;
 328
 329         spin_lock_bh(&m->tcf_lock);
 330         opt.action = m->tcf_action;
 331         opt.eaction = m->tcfm_eaction;
 332         dev = tcf_mirred_dev_dereference(m);
 333         if (dev)
 334                 opt.ifindex = dev->ifindex;
 335
 336         if (nla_put(skb, TCA_MIRRED_PARMS, sizeof(opt), &opt))
 337                 goto nla_put_failure;
 338
 339         tcf_tm_dump(&t, &m->tcf_tm);
 340         if (nla_put_64bit(skb, TCA_MIRRED_TM, sizeof(t), &t, TCA_MIRRED_PAD))
 341                 goto nla_put_failure;
 342         spin_unlock_bh(&m->tcf_lock);
 343
 344         return skb->len;
 345
 346 nla_put_failure:
 347         spin_unlock_bh(&m->tcf_lock);
 348         nlmsg_trim(skb, b);
 349         return -1;
 350 }
 351
 352 static int tcf_mirred_walker(struct net *net, struct sk_buff *skb,
 353                              struct netlink_callback *cb, int type,
 354                              const struct tc_action_ops *ops,
 355                              struct netlink_ext_ack *extack)
 356 {
 357         struct tc_action_net *tn = net_generic(net, mirred_net_id);
 358
 359         return tcf_generic_walker(tn, skb, cb, type, ops, extack);
 360 }
 361
 362 static int tcf_mirred_search(struct net *net, struct tc_action **a, u32 index)
 363 {
 364         struct tc_action_net *tn = net_generic(net, mirred_net_id);
 365
 366         return tcf_idr_search(tn, a, index);
 367 }
 368
 369 static int mirred_device_event(struct notifier_block *unused,
 370                                unsigned long event, void *ptr)
 371 {
 372         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 373         struct tcf_mirred *m;
 374
 375         ASSERT_RTNL();
 376         if (event == NETDEV_UNREGISTER) {
 377                 spin_lock(&mirred_list_lock);
 378                 list_for_each_entry(m, &mirred_list, tcfm_list) {
 379                         spin_lock_bh(&m->tcf_lock);
 380                         if (tcf_mirred_dev_dereference(m) == dev) {
 381                                 dev_put(dev);
 382                                 /* Note : no rcu grace period necessary, as
 383                                  * net_device are already rcu protected.
 384                                  */
 385                                 RCU_INIT_POINTER(m->tcfm_dev, NULL);
 386                         }
 387                         spin_unlock_bh(&m->tcf_lock);
 388                 }
 389                 spin_unlock(&mirred_list_lock);
 390         }
 391
 392         return NOTIFY_DONE;
 393 }
 394
 395 static struct notifier_block mirred_device_notifier = {
 396         .notifier_call = mirred_device_event,
 397 };
 398
 399 static struct net_device *tcf_mirred_get_dev(const struct tc_action *a)
 400 {
 401         struct tcf_mirred *m = to_mirred(a);
 402         struct net_device *dev;
 403
 404         rcu_read_lock();
 405         dev = rcu_dereference(m->tcfm_dev);
 406         if (dev)
 407                 dev_hold(dev);
 408         rcu_read_unlock();
 409
 410         return dev;
 411 }
 412
 413 static void tcf_mirred_put_dev(struct net_device *dev)
 414 {
 415         dev_put(dev);
 416 }
 417
 418 static struct tc_action_ops act_mirred_ops = {
 419         .kind           =       "mirred",
 420         .id             =       TCA_ID_MIRRED,
 421         .owner          =       THIS_MODULE,
 422         .act            =       tcf_mirred_act,
 423         .stats_update   =       tcf_stats_update,
 424         .dump           =       tcf_mirred_dump,
 425         .cleanup        =       tcf_mirred_release,
 426         .init           =       tcf_mirred_init,
 427         .walk           =       tcf_mirred_walker,
 428         .lookup         =       tcf_mirred_search,
 429         .size           =       sizeof(struct tcf_mirred),
 430         .get_dev        =       tcf_mirred_get_dev,
 431         .put_dev        =       tcf_mirred_put_dev,
 432 };
 433
 434 static __net_init int mirred_init_net(struct net *net)
 435 {
 436         struct tc_action_net *tn = net_generic(net, mirred_net_id);
 437
 438         return tc_action_net_init(tn, &act_mirred_ops);
 439 }
 440
 441 static void __net_exit mirred_exit_net(struct list_head *net_list)
 442 {
 443         tc_action_net_exit(net_list, mirred_net_id);
 444 }
 445
 446 static struct pernet_operations mirred_net_ops = {
 447         .init = mirred_init_net,
 448         .exit_batch = mirred_exit_net,
 449         .id   = &mirred_net_id,
 450         .size = sizeof(struct tc_action_net),
 451 };
 452
 453 MODULE_AUTHOR("Jamal Hadi Salim(2002)");
 454 MODULE_DESCRIPTION("Device Mirror/redirect actions");
 455 MODULE_LICENSE("GPL");
 456
 457 static int __init mirred_init_module(void)
 458 {
 459         int err = register_netdevice_notifier(&mirred_device_notifier);
 460         if (err)
 461                 return err;
 462
 463         pr_info("Mirror/redirect action on\n");
 464         return tcf_register_action(&act_mirred_ops, &mirred_net_ops);
 465 }
 466
 467 static void __exit mirred_cleanup_module(void)
 468 {
 469         tcf_unregister_action(&act_mirred_ops, &mirred_net_ops);
 470         unregister_netdevice_notifier(&mirred_device_notifier);
 471 }
 472
 473 module_init(mirred_init_module);
 474 module_exit(mirred_cleanup_module);