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