net/sched/act_mirred.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * net/sched/act_mirred.c       packet mirroring and redirect actions
   4  *
   5  * Authors:     Jamal Hadi Salim (2002-4)
   6  *
   7  * TODO: Add ingress support (and socket redirect support)
   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 <linux/if_arp.h>
  20 #include <net/net_namespace.h>
  21 #include <net/netlink.h>
  22 #include <net/pkt_sched.h>
  23 #include <net/pkt_cls.h>
  24 #include <linux/tc_act/tc_mirred.h>
  25 #include <net/tc_act/tc_mirred.h>
  26
  27 static LIST_HEAD(mirred_list);
  28 static DEFINE_SPINLOCK(mirred_list_lock);
  29
  30 #define MIRRED_RECURSION_LIMIT    4
  31 static DEFINE_PER_CPU(unsigned int, mirred_rec_level);
  32
  33 static bool tcf_mirred_is_act_redirect(int action)
  34 {
  35         return action == TCA_EGRESS_REDIR || action == TCA_INGRESS_REDIR;
  36 }
  37
  38 static bool tcf_mirred_act_wants_ingress(int action)
  39 {
  40         switch (action) {
  41         case TCA_EGRESS_REDIR:
  42         case TCA_EGRESS_MIRROR:
  43                 return false;
  44         case TCA_INGRESS_REDIR:
  45         case TCA_INGRESS_MIRROR:
  46                 return true;
  47         default:
  48                 BUG();
  49         }
  50 }
  51
  52 static bool tcf_mirred_can_reinsert(int action)
  53 {
  54         switch (action) {
  55         case TC_ACT_SHOT:
  56         case TC_ACT_STOLEN:
  57         case TC_ACT_QUEUED:
  58         case TC_ACT_TRAP:
  59                 return true;
  60         }
  61         return false;
  62 }
  63
  64 static struct net_device *tcf_mirred_dev_dereference(struct tcf_mirred *m)
  65 {
  66         return rcu_dereference_protected(m->tcfm_dev,
  67                                          lockdep_is_held(&m->tcf_lock));
  68 }
  69
  70 static void tcf_mirred_release(struct tc_action *a)
  71 {
  72         struct tcf_mirred *m = to_mirred(a);
  73         struct net_device *dev;
  74
  75         spin_lock(&mirred_list_lock);
  76         list_del(&m->tcfm_list);
  77         spin_unlock(&mirred_list_lock);
  78
  79         /* last reference to action, no need to lock */
  80         dev = rcu_dereference_protected(m->tcfm_dev, 1);
  81         if (dev)
  82                 dev_put(dev);
  83 }
  84
  85 static const struct nla_policy mirred_policy[TCA_MIRRED_MAX + 1] = {
  86         [TCA_MIRRED_PARMS]      = { .len = sizeof(struct tc_mirred) },
  87 };
  88
  89 static unsigned int mirred_net_id;
  90 static struct tc_action_ops act_mirred_ops;
  91
  92 static int tcf_mirred_init(struct net *net, struct nlattr *nla,
  93                            struct nlattr *est, struct tc_action **a,
  94                            int ovr, int bind, bool rtnl_held,
  95                            struct tcf_proto *tp,
  96                            struct netlink_ext_ack *extack)
  97 {
  98         struct tc_action_net *tn = net_generic(net, mirred_net_id);
  99         struct nlattr *tb[TCA_MIRRED_MAX + 1];
 100         struct tcf_chain *goto_ch = NULL;
 101         bool mac_header_xmit = false;
 102         struct tc_mirred *parm;
 103         struct tcf_mirred *m;
 104         struct net_device *dev;
 105         bool exists = false;
 106         int ret, err;
 107
 108         if (!nla) {
 109                 NL_SET_ERR_MSG_MOD(extack, "Mirred requires attributes to be passed");
 110                 return -EINVAL;
 111         }
 112         ret = nla_parse_nested_deprecated(tb, TCA_MIRRED_MAX, nla,
 113                                           mirred_policy, extack);
 114         if (ret < 0)
 115                 return ret;
 116         if (!tb[TCA_MIRRED_PARMS]) {
 117                 NL_SET_ERR_MSG_MOD(extack, "Missing required mirred parameters");
 118                 return -EINVAL;
 119         }
 120         parm = nla_data(tb[TCA_MIRRED_PARMS]);
 121
 122         err = tcf_idr_check_alloc(tn, &parm->index, a, bind);
 123         if (err < 0)
 124                 return err;
 125         exists = err;
 126         if (exists && bind)
 127                 return 0;
 128
 129         switch (parm->eaction) {
 130         case TCA_EGRESS_MIRROR:
 131         case TCA_EGRESS_REDIR:
 132         case TCA_INGRESS_REDIR:
 133         case TCA_INGRESS_MIRROR:
 134                 break;
 135         default:
 136                 if (exists)
 137                         tcf_idr_release(*a, bind);
 138                 else
 139                         tcf_idr_cleanup(tn, parm->index);
 140                 NL_SET_ERR_MSG_MOD(extack, "Unknown mirred option");
 141                 return -EINVAL;
 142         }
 143
 144         if (!exists) {
 145                 if (!parm->ifindex) {
 146                         tcf_idr_cleanup(tn, parm->index);
 147                         NL_SET_ERR_MSG_MOD(extack, "Specified device does not exist");
 148                         return -EINVAL;
 149                 }
 150                 ret = tcf_idr_create(tn, parm->index, est, a,
 151                                      &act_mirred_ops, bind, true);
 152                 if (ret) {
 153                         tcf_idr_cleanup(tn, parm->index);
 154                         return ret;
 155                 }
 156                 ret = ACT_P_CREATED;
 157         } else if (!ovr) {
 158                 tcf_idr_release(*a, bind);
 159                 return -EEXIST;
 160         }
 161
 162         m = to_mirred(*a);
 163         if (ret == ACT_P_CREATED)
 164                 INIT_LIST_HEAD(&m->tcfm_list);
 165
 166         err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack);
 167         if (err < 0)
 168                 goto release_idr;
 169
 170         spin_lock_bh(&m->tcf_lock);
 171
 172         if (parm->ifindex) {
 173                 dev = dev_get_by_index(net, parm->ifindex);
 174                 if (!dev) {
 175                         spin_unlock_bh(&m->tcf_lock);
 176                         err = -ENODEV;
 177                         goto put_chain;
 178                 }
 179                 mac_header_xmit = dev_is_mac_header_xmit(dev);
 180                 rcu_swap_protected(m->tcfm_dev, dev,
 181                                    lockdep_is_held(&m->tcf_lock));
 182                 if (dev)
 183                         dev_put(dev);
 184                 m->tcfm_mac_header_xmit = mac_header_xmit;
 185         }
 186         goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
 187         m->tcfm_eaction = parm->eaction;
 188         spin_unlock_bh(&m->tcf_lock);
 189         if (goto_ch)
 190                 tcf_chain_put_by_act(goto_ch);
 191
 192         if (ret == ACT_P_CREATED) {
 193                 spin_lock(&mirred_list_lock);
 194                 list_add(&m->tcfm_list, &mirred_list);
 195                 spin_unlock(&mirred_list_lock);
 196
 197                 tcf_idr_insert(tn, *a);
 198         }
 199
 200         return ret;
 201 put_chain:
 202         if (goto_ch)
 203                 tcf_chain_put_by_act(goto_ch);
 204 release_idr:
 205         tcf_idr_release(*a, bind);
 206         return err;
 207 }
 208
 209 static int tcf_mirred_act(struct sk_buff *skb, const struct tc_action *a,
 210                           struct tcf_result *res)
 211 {
 212         struct tcf_mirred *m = to_mirred(a);
 213         struct sk_buff *skb2 = skb;
 214         bool m_mac_header_xmit;
 215         struct net_device *dev;
 216         unsigned int rec_level;
 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         rec_level = __this_cpu_inc_return(mirred_rec_level);
 225         if (unlikely(rec_level > MIRRED_RECURSION_LIMIT)) {
 226                 net_warn_ratelimited("Packet exceeded mirred recursion limit on dev %s\n",
 227                                      netdev_name(skb->dev));
 228                 __this_cpu_dec(mirred_rec_level);
 229                 return TC_ACT_SHOT;
 230         }
 231
 232         tcf_lastuse_update(&m->tcf_tm);
 233         bstats_cpu_update(this_cpu_ptr(m->common.cpu_bstats), skb);
 234
 235         m_mac_header_xmit = READ_ONCE(m->tcfm_mac_header_xmit);
 236         m_eaction = READ_ONCE(m->tcfm_eaction);
 237         retval = READ_ONCE(m->tcf_action);
 238         dev = rcu_dereference_bh(m->tcfm_dev);
 239         if (unlikely(!dev)) {
 240                 pr_notice_once("tc mirred: target device is gone\n");
 241                 goto out;
 242         }
 243
 244         if (unlikely(!(dev->flags & IFF_UP))) {
 245                 net_notice_ratelimited("tc mirred to Houston: device %s is down\n",
 246                                        dev->name);
 247                 goto out;
 248         }
 249
 250         /* we could easily avoid the clone only if called by ingress and clsact;
 251          * since we can't easily detect the clsact caller, skip clone only for
 252          * ingress - that covers the TC S/W datapath.
 253          */
 254         is_redirect = tcf_mirred_is_act_redirect(m_eaction);
 255         use_reinsert = skb_at_tc_ingress(skb) && is_redirect &&
 256                        tcf_mirred_can_reinsert(retval);
 257         if (!use_reinsert) {
 258                 skb2 = skb_clone(skb, GFP_ATOMIC);
 259                 if (!skb2)
 260                         goto out;
 261         }
 262
 263         /* If action's target direction differs than filter's direction,
 264          * and devices expect a mac header on xmit, then mac push/pull is
 265          * needed.
 266          */
 267         want_ingress = tcf_mirred_act_wants_ingress(m_eaction);
 268         if (skb_at_tc_ingress(skb) != want_ingress && m_mac_header_xmit) {
 269                 if (!skb_at_tc_ingress(skb)) {
 270                         /* caught at egress, act ingress: pull mac */
 271                         mac_len = skb_network_header(skb) - skb_mac_header(skb);
 272                         skb_pull_rcsum(skb2, mac_len);
 273                 } else {
 274                         /* caught at ingress, act egress: push mac */
 275                         skb_push_rcsum(skb2, skb->mac_len);
 276                 }
 277         }
 278
 279         skb2->skb_iif = skb->dev->ifindex;
 280         skb2->dev = dev;
 281
 282         /* mirror is always swallowed */
 283         if (is_redirect) {
 284                 skb2->tc_redirected = 1;
 285                 skb2->tc_from_ingress = skb2->tc_at_ingress;
 286                 if (skb2->tc_from_ingress)
 287                         skb2->tstamp = 0;
 288                 /* let's the caller reinsert the packet, if possible */
 289                 if (use_reinsert) {
 290                         res->ingress = want_ingress;
 291                         res->qstats = this_cpu_ptr(m->common.cpu_qstats);
 292                         skb_tc_reinsert(skb, res);
 293                         __this_cpu_dec(mirred_rec_level);
 294                         return TC_ACT_CONSUMED;
 295                 }
 296         }
 297
 298         if (!want_ingress)
 299                 err = dev_queue_xmit(skb2);
 300         else
 301                 err = netif_receive_skb(skb2);
 302
 303         if (err) {
 304 out:
 305                 qstats_overlimit_inc(this_cpu_ptr(m->common.cpu_qstats));
 306                 if (tcf_mirred_is_act_redirect(m_eaction))
 307                         retval = TC_ACT_SHOT;
 308         }
 309         __this_cpu_dec(mirred_rec_level);
 310
 311         return retval;
 312 }
 313
 314 static void tcf_stats_update(struct tc_action *a, u64 bytes, u32 packets,
 315                              u64 lastuse, bool hw)
 316 {
 317         struct tcf_mirred *m = to_mirred(a);
 318         struct tcf_t *tm = &m->tcf_tm;
 319
 320         _bstats_cpu_update(this_cpu_ptr(a->cpu_bstats), bytes, packets);
 321         if (hw)
 322                 _bstats_cpu_update(this_cpu_ptr(a->cpu_bstats_hw),
 323                                    bytes, packets);
 324         tm->lastuse = max_t(u64, tm->lastuse, lastuse);
 325 }
 326
 327 static int tcf_mirred_dump(struct sk_buff *skb, struct tc_action *a, int bind,
 328                            int ref)
 329 {
 330         unsigned char *b = skb_tail_pointer(skb);
 331         struct tcf_mirred *m = to_mirred(a);
 332         struct tc_mirred opt = {
 333                 .index   = m->tcf_index,
 334                 .refcnt  = refcount_read(&m->tcf_refcnt) - ref,
 335                 .bindcnt = atomic_read(&m->tcf_bindcnt) - bind,
 336         };
 337         struct net_device *dev;
 338         struct tcf_t t;
 339
 340         spin_lock_bh(&m->tcf_lock);
 341         opt.action = m->tcf_action;
 342         opt.eaction = m->tcfm_eaction;
 343         dev = tcf_mirred_dev_dereference(m);
 344         if (dev)
 345                 opt.ifindex = dev->ifindex;
 346
 347         if (nla_put(skb, TCA_MIRRED_PARMS, sizeof(opt), &opt))
 348                 goto nla_put_failure;
 349
 350         tcf_tm_dump(&t, &m->tcf_tm);
 351         if (nla_put_64bit(skb, TCA_MIRRED_TM, sizeof(t), &t, TCA_MIRRED_PAD))
 352                 goto nla_put_failure;
 353         spin_unlock_bh(&m->tcf_lock);
 354
 355         return skb->len;
 356
 357 nla_put_failure:
 358         spin_unlock_bh(&m->tcf_lock);
 359         nlmsg_trim(skb, b);
 360         return -1;
 361 }
 362
 363 static int tcf_mirred_walker(struct net *net, struct sk_buff *skb,
 364                              struct netlink_callback *cb, int type,
 365                              const struct tc_action_ops *ops,
 366                              struct netlink_ext_ack *extack)
 367 {
 368         struct tc_action_net *tn = net_generic(net, mirred_net_id);
 369
 370         return tcf_generic_walker(tn, skb, cb, type, ops, extack);
 371 }
 372
 373 static int tcf_mirred_search(struct net *net, struct tc_action **a, u32 index)
 374 {
 375         struct tc_action_net *tn = net_generic(net, mirred_net_id);
 376
 377         return tcf_idr_search(tn, a, index);
 378 }
 379
 380 static int mirred_device_event(struct notifier_block *unused,
 381                                unsigned long event, void *ptr)
 382 {
 383         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 384         struct tcf_mirred *m;
 385
 386         ASSERT_RTNL();
 387         if (event == NETDEV_UNREGISTER) {
 388                 spin_lock(&mirred_list_lock);
 389                 list_for_each_entry(m, &mirred_list, tcfm_list) {
 390                         spin_lock_bh(&m->tcf_lock);
 391                         if (tcf_mirred_dev_dereference(m) == dev) {
 392                                 dev_put(dev);
 393                                 /* Note : no rcu grace period necessary, as
 394                                  * net_device are already rcu protected.
 395                                  */
 396                                 RCU_INIT_POINTER(m->tcfm_dev, NULL);
 397                         }
 398                         spin_unlock_bh(&m->tcf_lock);
 399                 }
 400                 spin_unlock(&mirred_list_lock);
 401         }
 402
 403         return NOTIFY_DONE;
 404 }
 405
 406 static struct notifier_block mirred_device_notifier = {
 407         .notifier_call = mirred_device_event,
 408 };
 409
 410 static struct net_device *tcf_mirred_get_dev(const struct tc_action *a)
 411 {
 412         struct tcf_mirred *m = to_mirred(a);
 413         struct net_device *dev;
 414
 415         rcu_read_lock();
 416         dev = rcu_dereference(m->tcfm_dev);
 417         if (dev)
 418                 dev_hold(dev);
 419         rcu_read_unlock();
 420
 421         return dev;
 422 }
 423
 424 static void tcf_mirred_put_dev(struct net_device *dev)
 425 {
 426         dev_put(dev);
 427 }
 428
 429 static size_t tcf_mirred_get_fill_size(const struct tc_action *act)
 430 {
 431         return nla_total_size(sizeof(struct tc_mirred));
 432 }
 433
 434 static struct tc_action_ops act_mirred_ops = {
 435         .kind           =       "mirred",
 436         .id             =       TCA_ID_MIRRED,
 437         .owner          =       THIS_MODULE,
 438         .act            =       tcf_mirred_act,
 439         .stats_update   =       tcf_stats_update,
 440         .dump           =       tcf_mirred_dump,
 441         .cleanup        =       tcf_mirred_release,
 442         .init           =       tcf_mirred_init,
 443         .walk           =       tcf_mirred_walker,
 444         .lookup         =       tcf_mirred_search,
 445         .get_fill_size  =       tcf_mirred_get_fill_size,
 446         .size           =       sizeof(struct tcf_mirred),
 447         .get_dev        =       tcf_mirred_get_dev,
 448         .put_dev        =       tcf_mirred_put_dev,
 449 };
 450
 451 static __net_init int mirred_init_net(struct net *net)
 452 {
 453         struct tc_action_net *tn = net_generic(net, mirred_net_id);
 454
 455         return tc_action_net_init(tn, &act_mirred_ops);
 456 }
 457
 458 static void __net_exit mirred_exit_net(struct list_head *net_list)
 459 {
 460         tc_action_net_exit(net_list, mirred_net_id);
 461 }
 462
 463 static struct pernet_operations mirred_net_ops = {
 464         .init = mirred_init_net,
 465         .exit_batch = mirred_exit_net,
 466         .id   = &mirred_net_id,
 467         .size = sizeof(struct tc_action_net),
 468 };
 469
 470 MODULE_AUTHOR("Jamal Hadi Salim(2002)");
 471 MODULE_DESCRIPTION("Device Mirror/redirect actions");
 472 MODULE_LICENSE("GPL");
 473
 474 static int __init mirred_init_module(void)
 475 {
 476         int err = register_netdevice_notifier(&mirred_device_notifier);
 477         if (err)
 478                 return err;
 479
 480         pr_info("Mirror/redirect action on\n");
 481         return tcf_register_action(&act_mirred_ops, &mirred_net_ops);
 482 }
 483
 484 static void __exit mirred_cleanup_module(void)
 485 {
 486         tcf_unregister_action(&act_mirred_ops, &mirred_net_ops);
 487         unregister_netdevice_notifier(&mirred_device_notifier);
 488 }
 489
 490 module_init(mirred_init_module);
 491 module_exit(mirred_cleanup_module);