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