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/dst.h>
  23 #include <net/pkt_sched.h>
  24 #include <net/pkt_cls.h>
  25 #include <linux/tc_act/tc_mirred.h>
  26 #include <net/tc_act/tc_mirred.h>
  27
  28 static LIST_HEAD(mirred_list);
  29 static DEFINE_SPINLOCK(mirred_list_lock);
  30
  31 #define MIRRED_RECURSION_LIMIT    4
  32 static DEFINE_PER_CPU(unsigned int, mirred_rec_level);
  33
  34 static bool tcf_mirred_is_act_redirect(int action)
  35 {
  36         return action == TCA_EGRESS_REDIR || action == TCA_INGRESS_REDIR;
  37 }
  38
  39 static bool tcf_mirred_act_wants_ingress(int action)
  40 {
  41         switch (action) {
  42         case TCA_EGRESS_REDIR:
  43         case TCA_EGRESS_MIRROR:
  44                 return false;
  45         case TCA_INGRESS_REDIR:
  46         case TCA_INGRESS_MIRROR:
  47                 return true;
  48         default:
  49                 BUG();
  50         }
  51 }
  52
  53 static bool tcf_mirred_can_reinsert(int action)
  54 {
  55         switch (action) {
  56         case TC_ACT_SHOT:
  57         case TC_ACT_STOLEN:
  58         case TC_ACT_QUEUED:
  59         case TC_ACT_TRAP:
  60                 return true;
  61         }
  62         return false;
  63 }
  64
  65 static struct net_device *tcf_mirred_dev_dereference(struct tcf_mirred *m)
  66 {
  67         return rcu_dereference_protected(m->tcfm_dev,
  68                                          lockdep_is_held(&m->tcf_lock));
  69 }
  70
  71 static void tcf_mirred_release(struct tc_action *a)
  72 {
  73         struct tcf_mirred *m = to_mirred(a);
  74         struct net_device *dev;
  75
  76         spin_lock(&mirred_list_lock);
  77         list_del(&m->tcfm_list);
  78         spin_unlock(&mirred_list_lock);
  79
  80         /* last reference to action, no need to lock */
  81         dev = rcu_dereference_protected(m->tcfm_dev, 1);
  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                            struct tcf_proto *tp,
  95                            u32 flags, struct netlink_ext_ack *extack)
  96 {
  97         struct tc_action_net *tn = net_generic(net, mirred_net_id);
  98         bool bind = flags & TCA_ACT_FLAGS_BIND;
  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         u32 index;
 108
 109         if (!nla) {
 110                 NL_SET_ERR_MSG_MOD(extack, "Mirred requires attributes to be passed");
 111                 return -EINVAL;
 112         }
 113         ret = nla_parse_nested_deprecated(tb, TCA_MIRRED_MAX, nla,
 114                                           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         index = parm->index;
 123         err = tcf_idr_check_alloc(tn, &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, 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, index);
 148                         NL_SET_ERR_MSG_MOD(extack, "Specified device does not exist");
 149                         return -EINVAL;
 150                 }
 151                 ret = tcf_idr_create_from_flags(tn, index, est, a,
 152                                                 &act_mirred_ops, bind, flags);
 153                 if (ret) {
 154                         tcf_idr_cleanup(tn, index);
 155                         return ret;
 156                 }
 157                 ret = ACT_P_CREATED;
 158         } else if (!(flags & TCA_ACT_FLAGS_REPLACE)) {
 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                 dev = rcu_replace_pointer(m->tcfm_dev, dev,
 182                                           lockdep_is_held(&m->tcf_lock));
 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
 198         return ret;
 199 put_chain:
 200         if (goto_ch)
 201                 tcf_chain_put_by_act(goto_ch);
 202 release_idr:
 203         tcf_idr_release(*a, bind);
 204         return err;
 205 }
 206
 207 static int tcf_mirred_forward(bool want_ingress, struct sk_buff *skb)
 208 {
 209         int err;
 210
 211         if (!want_ingress)
 212                 err = tcf_dev_queue_xmit(skb, dev_queue_xmit);
 213         else
 214                 err = netif_receive_skb(skb);
 215
 216         return err;
 217 }
 218
 219 static int tcf_mirred_act(struct sk_buff *skb, const struct tc_action *a,
 220                           struct tcf_result *res)
 221 {
 222         struct tcf_mirred *m = to_mirred(a);
 223         struct sk_buff *skb2 = skb;
 224         bool m_mac_header_xmit;
 225         struct net_device *dev;
 226         unsigned int rec_level;
 227         int retval, err = 0;
 228         bool use_reinsert;
 229         bool want_ingress;
 230         bool is_redirect;
 231         bool expects_nh;
 232         bool at_ingress;
 233         int m_eaction;
 234         int mac_len;
 235         bool at_nh;
 236
 237         rec_level = __this_cpu_inc_return(mirred_rec_level);
 238         if (unlikely(rec_level > MIRRED_RECURSION_LIMIT)) {
 239                 net_warn_ratelimited("Packet exceeded mirred recursion limit on dev %s\n",
 240                                      netdev_name(skb->dev));
 241                 __this_cpu_dec(mirred_rec_level);
 242                 return TC_ACT_SHOT;
 243         }
 244
 245         tcf_lastuse_update(&m->tcf_tm);
 246         tcf_action_update_bstats(&m->common, skb);
 247
 248         m_mac_header_xmit = READ_ONCE(m->tcfm_mac_header_xmit);
 249         m_eaction = READ_ONCE(m->tcfm_eaction);
 250         retval = READ_ONCE(m->tcf_action);
 251         dev = rcu_dereference_bh(m->tcfm_dev);
 252         if (unlikely(!dev)) {
 253                 pr_notice_once("tc mirred: target device is gone\n");
 254                 goto out;
 255         }
 256
 257         if (unlikely(!(dev->flags & IFF_UP))) {
 258                 net_notice_ratelimited("tc mirred to Houston: device %s is down\n",
 259                                        dev->name);
 260                 goto out;
 261         }
 262
 263         /* we could easily avoid the clone only if called by ingress and clsact;
 264          * since we can't easily detect the clsact caller, skip clone only for
 265          * ingress - that covers the TC S/W datapath.
 266          */
 267         is_redirect = tcf_mirred_is_act_redirect(m_eaction);
 268         at_ingress = skb_at_tc_ingress(skb);
 269         use_reinsert = at_ingress && is_redirect &&
 270                        tcf_mirred_can_reinsert(retval);
 271         if (!use_reinsert) {
 272                 skb2 = skb_clone(skb, GFP_ATOMIC);
 273                 if (!skb2)
 274                         goto out;
 275         }
 276
 277         want_ingress = tcf_mirred_act_wants_ingress(m_eaction);
 278
 279         /* All mirred/redirected skbs should clear previous ct info */
 280         nf_reset_ct(skb2);
 281         if (want_ingress && !at_ingress) /* drop dst for egress -> ingress */
 282                 skb_dst_drop(skb2);
 283
 284         expects_nh = want_ingress || !m_mac_header_xmit;
 285         at_nh = skb->data == skb_network_header(skb);
 286         if (at_nh != expects_nh) {
 287                 mac_len = skb_at_tc_ingress(skb) ? skb->mac_len :
 288                           skb_network_header(skb) - skb_mac_header(skb);
 289                 if (expects_nh) {
 290                         /* target device/action expect data at nh */
 291                         skb_pull_rcsum(skb2, mac_len);
 292                 } else {
 293                         /* target device/action expect data at mac */
 294                         skb_push_rcsum(skb2, mac_len);
 295                 }
 296         }
 297
 298         skb2->skb_iif = skb->dev->ifindex;
 299         skb2->dev = dev;
 300
 301         /* mirror is always swallowed */
 302         if (is_redirect) {
 303                 skb_set_redirected(skb2, skb2->tc_at_ingress);
 304
 305                 /* let's the caller reinsert the packet, if possible */
 306                 if (use_reinsert) {
 307                         res->ingress = want_ingress;
 308                         err = tcf_mirred_forward(res->ingress, skb);
 309                         if (err)
 310                                 tcf_action_inc_overlimit_qstats(&m->common);
 311                         __this_cpu_dec(mirred_rec_level);
 312                         return TC_ACT_CONSUMED;
 313                 }
 314         }
 315
 316         err = tcf_mirred_forward(want_ingress, skb2);
 317         if (err) {
 318 out:
 319                 tcf_action_inc_overlimit_qstats(&m->common);
 320                 if (tcf_mirred_is_act_redirect(m_eaction))
 321                         retval = TC_ACT_SHOT;
 322         }
 323         __this_cpu_dec(mirred_rec_level);
 324
 325         return retval;
 326 }
 327
 328 static void tcf_stats_update(struct tc_action *a, u64 bytes, u64 packets,
 329                              u64 drops, u64 lastuse, bool hw)
 330 {
 331         struct tcf_mirred *m = to_mirred(a);
 332         struct tcf_t *tm = &m->tcf_tm;
 333
 334         tcf_action_update_stats(a, bytes, packets, drops, hw);
 335         tm->lastuse = max_t(u64, tm->lastuse, lastuse);
 336 }
 337
 338 static int tcf_mirred_dump(struct sk_buff *skb, struct tc_action *a, int bind,
 339                            int ref)
 340 {
 341         unsigned char *b = skb_tail_pointer(skb);
 342         struct tcf_mirred *m = to_mirred(a);
 343         struct tc_mirred opt = {
 344                 .index   = m->tcf_index,
 345                 .refcnt  = refcount_read(&m->tcf_refcnt) - ref,
 346                 .bindcnt = atomic_read(&m->tcf_bindcnt) - bind,
 347         };
 348         struct net_device *dev;
 349         struct tcf_t t;
 350
 351         spin_lock_bh(&m->tcf_lock);
 352         opt.action = m->tcf_action;
 353         opt.eaction = m->tcfm_eaction;
 354         dev = tcf_mirred_dev_dereference(m);
 355         if (dev)
 356                 opt.ifindex = dev->ifindex;
 357
 358         if (nla_put(skb, TCA_MIRRED_PARMS, sizeof(opt), &opt))
 359                 goto nla_put_failure;
 360
 361         tcf_tm_dump(&t, &m->tcf_tm);
 362         if (nla_put_64bit(skb, TCA_MIRRED_TM, sizeof(t), &t, TCA_MIRRED_PAD))
 363                 goto nla_put_failure;
 364         spin_unlock_bh(&m->tcf_lock);
 365
 366         return skb->len;
 367
 368 nla_put_failure:
 369         spin_unlock_bh(&m->tcf_lock);
 370         nlmsg_trim(skb, b);
 371         return -1;
 372 }
 373
 374 static int tcf_mirred_walker(struct net *net, struct sk_buff *skb,
 375                              struct netlink_callback *cb, int type,
 376                              const struct tc_action_ops *ops,
 377                              struct netlink_ext_ack *extack)
 378 {
 379         struct tc_action_net *tn = net_generic(net, mirred_net_id);
 380
 381         return tcf_generic_walker(tn, skb, cb, type, ops, extack);
 382 }
 383
 384 static int tcf_mirred_search(struct net *net, struct tc_action **a, u32 index)
 385 {
 386         struct tc_action_net *tn = net_generic(net, mirred_net_id);
 387
 388         return tcf_idr_search(tn, a, index);
 389 }
 390
 391 static int mirred_device_event(struct notifier_block *unused,
 392                                unsigned long event, void *ptr)
 393 {
 394         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 395         struct tcf_mirred *m;
 396
 397         ASSERT_RTNL();
 398         if (event == NETDEV_UNREGISTER) {
 399                 spin_lock(&mirred_list_lock);
 400                 list_for_each_entry(m, &mirred_list, tcfm_list) {
 401                         spin_lock_bh(&m->tcf_lock);
 402                         if (tcf_mirred_dev_dereference(m) == dev) {
 403                                 dev_put(dev);
 404                                 /* Note : no rcu grace period necessary, as
 405                                  * net_device are already rcu protected.
 406                                  */
 407                                 RCU_INIT_POINTER(m->tcfm_dev, NULL);
 408                         }
 409                         spin_unlock_bh(&m->tcf_lock);
 410                 }
 411                 spin_unlock(&mirred_list_lock);
 412         }
 413
 414         return NOTIFY_DONE;
 415 }
 416
 417 static struct notifier_block mirred_device_notifier = {
 418         .notifier_call = mirred_device_event,
 419 };
 420
 421 static void tcf_mirred_dev_put(void *priv)
 422 {
 423         struct net_device *dev = priv;
 424
 425         dev_put(dev);
 426 }
 427
 428 static struct net_device *
 429 tcf_mirred_get_dev(const struct tc_action *a,
 430                    tc_action_priv_destructor *destructor)
 431 {
 432         struct tcf_mirred *m = to_mirred(a);
 433         struct net_device *dev;
 434
 435         rcu_read_lock();
 436         dev = rcu_dereference(m->tcfm_dev);
 437         if (dev) {
 438                 dev_hold(dev);
 439                 *destructor = tcf_mirred_dev_put;
 440         }
 441         rcu_read_unlock();
 442
 443         return dev;
 444 }
 445
 446 static size_t tcf_mirred_get_fill_size(const struct tc_action *act)
 447 {
 448         return nla_total_size(sizeof(struct tc_mirred));
 449 }
 450
 451 static struct tc_action_ops act_mirred_ops = {
 452         .kind           =       "mirred",
 453         .id             =       TCA_ID_MIRRED,
 454         .owner          =       THIS_MODULE,
 455         .act            =       tcf_mirred_act,
 456         .stats_update   =       tcf_stats_update,
 457         .dump           =       tcf_mirred_dump,
 458         .cleanup        =       tcf_mirred_release,
 459         .init           =       tcf_mirred_init,
 460         .walk           =       tcf_mirred_walker,
 461         .lookup         =       tcf_mirred_search,
 462         .get_fill_size  =       tcf_mirred_get_fill_size,
 463         .size           =       sizeof(struct tcf_mirred),
 464         .get_dev        =       tcf_mirred_get_dev,
 465 };
 466
 467 static __net_init int mirred_init_net(struct net *net)
 468 {
 469         struct tc_action_net *tn = net_generic(net, mirred_net_id);
 470
 471         return tc_action_net_init(net, tn, &act_mirred_ops);
 472 }
 473
 474 static void __net_exit mirred_exit_net(struct list_head *net_list)
 475 {
 476         tc_action_net_exit(net_list, mirred_net_id);
 477 }
 478
 479 static struct pernet_operations mirred_net_ops = {
 480         .init = mirred_init_net,
 481         .exit_batch = mirred_exit_net,
 482         .id   = &mirred_net_id,
 483         .size = sizeof(struct tc_action_net),
 484 };
 485
 486 MODULE_AUTHOR("Jamal Hadi Salim(2002)");
 487 MODULE_DESCRIPTION("Device Mirror/redirect actions");
 488 MODULE_LICENSE("GPL");
 489
 490 static int __init mirred_init_module(void)
 491 {
 492         int err = register_netdevice_notifier(&mirred_device_notifier);
 493         if (err)
 494                 return err;
 495
 496         pr_info("Mirror/redirect action on\n");
 497         err = tcf_register_action(&act_mirred_ops, &mirred_net_ops);
 498         if (err)
 499                 unregister_netdevice_notifier(&mirred_device_notifier);
 500
 501         return err;
 502 }
 503
 504 static void __exit mirred_cleanup_module(void)
 505 {
 506         tcf_unregister_action(&act_mirred_ops, &mirred_net_ops);
 507         unregister_netdevice_notifier(&mirred_device_notifier);
 508 }
 509
 510 module_init(mirred_init_module);
 511 module_exit(mirred_cleanup_module);