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                            u32 flags, 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         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 (!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                 dev = rcu_replace_pointer(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         unsigned int rec_level;
 218         int retval, err = 0;
 219         bool use_reinsert;
 220         bool want_ingress;
 221         bool is_redirect;
 222         bool expects_nh;
 223         int m_eaction;
 224         int mac_len;
 225         bool at_nh;
 226
 227         rec_level = __this_cpu_inc_return(mirred_rec_level);
 228         if (unlikely(rec_level > MIRRED_RECURSION_LIMIT)) {
 229                 net_warn_ratelimited("Packet exceeded mirred recursion limit on dev %s\n",
 230                                      netdev_name(skb->dev));
 231                 __this_cpu_dec(mirred_rec_level);
 232                 return TC_ACT_SHOT;
 233         }
 234
 235         tcf_lastuse_update(&m->tcf_tm);
 236         tcf_action_update_bstats(&m->common, skb);
 237
 238         m_mac_header_xmit = READ_ONCE(m->tcfm_mac_header_xmit);
 239         m_eaction = READ_ONCE(m->tcfm_eaction);
 240         retval = READ_ONCE(m->tcf_action);
 241         dev = rcu_dereference_bh(m->tcfm_dev);
 242         if (unlikely(!dev)) {
 243                 pr_notice_once("tc mirred: target device is gone\n");
 244                 goto out;
 245         }
 246
 247         if (unlikely(!(dev->flags & IFF_UP))) {
 248                 net_notice_ratelimited("tc mirred to Houston: device %s is down\n",
 249                                        dev->name);
 250                 goto out;
 251         }
 252
 253         /* we could easily avoid the clone only if called by ingress and clsact;
 254          * since we can't easily detect the clsact caller, skip clone only for
 255          * ingress - that covers the TC S/W datapath.
 256          */
 257         is_redirect = tcf_mirred_is_act_redirect(m_eaction);
 258         use_reinsert = skb_at_tc_ingress(skb) && is_redirect &&
 259                        tcf_mirred_can_reinsert(retval);
 260         if (!use_reinsert) {
 261                 skb2 = skb_clone(skb, GFP_ATOMIC);
 262                 if (!skb2)
 263                         goto out;
 264         }
 265
 266         want_ingress = tcf_mirred_act_wants_ingress(m_eaction);
 267
 268         expects_nh = want_ingress || !m_mac_header_xmit;
 269         at_nh = skb->data == skb_network_header(skb);
 270         if (at_nh != expects_nh) {
 271                 mac_len = skb_at_tc_ingress(skb) ? skb->mac_len :
 272                           skb_network_header(skb) - skb_mac_header(skb);
 273                 if (expects_nh) {
 274                         /* target device/action expect data at nh */
 275                         skb_pull_rcsum(skb2, mac_len);
 276                 } else {
 277                         /* target device/action expect data at mac */
 278                         skb_push_rcsum(skb2, mac_len);
 279                 }
 280         }
 281
 282         skb2->skb_iif = skb->dev->ifindex;
 283         skb2->dev = dev;
 284
 285         /* mirror is always swallowed */
 286         if (is_redirect) {
 287                 skb_set_redirected(skb2, skb2->tc_at_ingress);
 288
 289                 /* let's the caller reinsert the packet, if possible */
 290                 if (use_reinsert) {
 291                         res->ingress = want_ingress;
 292                         if (skb_tc_reinsert(skb, res))
 293                                 tcf_action_inc_overlimit_qstats(&m->common);
 294                         __this_cpu_dec(mirred_rec_level);
 295                         return TC_ACT_CONSUMED;
 296                 }
 297         }
 298
 299         if (!want_ingress)
 300                 err = dev_queue_xmit(skb2);
 301         else
 302                 err = netif_receive_skb(skb2);
 303
 304         if (err) {
 305 out:
 306                 tcf_action_inc_overlimit_qstats(&m->common);
 307                 if (tcf_mirred_is_act_redirect(m_eaction))
 308                         retval = TC_ACT_SHOT;
 309         }
 310         __this_cpu_dec(mirred_rec_level);
 311
 312         return retval;
 313 }
 314
 315 static void tcf_stats_update(struct tc_action *a, u64 bytes, u32 packets,
 316                              u64 lastuse, bool hw)
 317 {
 318         struct tcf_mirred *m = to_mirred(a);
 319         struct tcf_t *tm = &m->tcf_tm;
 320
 321         tcf_action_update_stats(a, bytes, packets, false, hw);
 322         tm->lastuse = max_t(u64, tm->lastuse, lastuse);
 323 }
 324
 325 static int tcf_mirred_dump(struct sk_buff *skb, struct tc_action *a, int bind,
 326                            int ref)
 327 {
 328         unsigned char *b = skb_tail_pointer(skb);
 329         struct tcf_mirred *m = to_mirred(a);
 330         struct tc_mirred opt = {
 331                 .index   = m->tcf_index,
 332                 .refcnt  = refcount_read(&m->tcf_refcnt) - ref,
 333                 .bindcnt = atomic_read(&m->tcf_bindcnt) - bind,
 334         };
 335         struct net_device *dev;
 336         struct tcf_t t;
 337
 338         spin_lock_bh(&m->tcf_lock);
 339         opt.action = m->tcf_action;
 340         opt.eaction = m->tcfm_eaction;
 341         dev = tcf_mirred_dev_dereference(m);
 342         if (dev)
 343                 opt.ifindex = dev->ifindex;
 344
 345         if (nla_put(skb, TCA_MIRRED_PARMS, sizeof(opt), &opt))
 346                 goto nla_put_failure;
 347
 348         tcf_tm_dump(&t, &m->tcf_tm);
 349         if (nla_put_64bit(skb, TCA_MIRRED_TM, sizeof(t), &t, TCA_MIRRED_PAD))
 350                 goto nla_put_failure;
 351         spin_unlock_bh(&m->tcf_lock);
 352
 353         return skb->len;
 354
 355 nla_put_failure:
 356         spin_unlock_bh(&m->tcf_lock);
 357         nlmsg_trim(skb, b);
 358         return -1;
 359 }
 360
 361 static int tcf_mirred_walker(struct net *net, struct sk_buff *skb,
 362                              struct netlink_callback *cb, int type,
 363                              const struct tc_action_ops *ops,
 364                              struct netlink_ext_ack *extack)
 365 {
 366         struct tc_action_net *tn = net_generic(net, mirred_net_id);
 367
 368         return tcf_generic_walker(tn, skb, cb, type, ops, extack);
 369 }
 370
 371 static int tcf_mirred_search(struct net *net, struct tc_action **a, u32 index)
 372 {
 373         struct tc_action_net *tn = net_generic(net, mirred_net_id);
 374
 375         return tcf_idr_search(tn, a, index);
 376 }
 377
 378 static int mirred_device_event(struct notifier_block *unused,
 379                                unsigned long event, void *ptr)
 380 {
 381         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 382         struct tcf_mirred *m;
 383
 384         ASSERT_RTNL();
 385         if (event == NETDEV_UNREGISTER) {
 386                 spin_lock(&mirred_list_lock);
 387                 list_for_each_entry(m, &mirred_list, tcfm_list) {
 388                         spin_lock_bh(&m->tcf_lock);
 389                         if (tcf_mirred_dev_dereference(m) == dev) {
 390                                 dev_put(dev);
 391                                 /* Note : no rcu grace period necessary, as
 392                                  * net_device are already rcu protected.
 393                                  */
 394                                 RCU_INIT_POINTER(m->tcfm_dev, NULL);
 395                         }
 396                         spin_unlock_bh(&m->tcf_lock);
 397                 }
 398                 spin_unlock(&mirred_list_lock);
 399         }
 400
 401         return NOTIFY_DONE;
 402 }
 403
 404 static struct notifier_block mirred_device_notifier = {
 405         .notifier_call = mirred_device_event,
 406 };
 407
 408 static void tcf_mirred_dev_put(void *priv)
 409 {
 410         struct net_device *dev = priv;
 411
 412         dev_put(dev);
 413 }
 414
 415 static struct net_device *
 416 tcf_mirred_get_dev(const struct tc_action *a,
 417                    tc_action_priv_destructor *destructor)
 418 {
 419         struct tcf_mirred *m = to_mirred(a);
 420         struct net_device *dev;
 421
 422         rcu_read_lock();
 423         dev = rcu_dereference(m->tcfm_dev);
 424         if (dev) {
 425                 dev_hold(dev);
 426                 *destructor = tcf_mirred_dev_put;
 427         }
 428         rcu_read_unlock();
 429
 430         return dev;
 431 }
 432
 433 static size_t tcf_mirred_get_fill_size(const struct tc_action *act)
 434 {
 435         return nla_total_size(sizeof(struct tc_mirred));
 436 }
 437
 438 static struct tc_action_ops act_mirred_ops = {
 439         .kind           =       "mirred",
 440         .id             =       TCA_ID_MIRRED,
 441         .owner          =       THIS_MODULE,
 442         .act            =       tcf_mirred_act,
 443         .stats_update   =       tcf_stats_update,
 444         .dump           =       tcf_mirred_dump,
 445         .cleanup        =       tcf_mirred_release,
 446         .init           =       tcf_mirred_init,
 447         .walk           =       tcf_mirred_walker,
 448         .lookup         =       tcf_mirred_search,
 449         .get_fill_size  =       tcf_mirred_get_fill_size,
 450         .size           =       sizeof(struct tcf_mirred),
 451         .get_dev        =       tcf_mirred_get_dev,
 452 };
 453
 454 static __net_init int mirred_init_net(struct net *net)
 455 {
 456         struct tc_action_net *tn = net_generic(net, mirred_net_id);
 457
 458         return tc_action_net_init(net, tn, &act_mirred_ops);
 459 }
 460
 461 static void __net_exit mirred_exit_net(struct list_head *net_list)
 462 {
 463         tc_action_net_exit(net_list, mirred_net_id);
 464 }
 465
 466 static struct pernet_operations mirred_net_ops = {
 467         .init = mirred_init_net,
 468         .exit_batch = mirred_exit_net,
 469         .id   = &mirred_net_id,
 470         .size = sizeof(struct tc_action_net),
 471 };
 472
 473 MODULE_AUTHOR("Jamal Hadi Salim(2002)");
 474 MODULE_DESCRIPTION("Device Mirror/redirect actions");
 475 MODULE_LICENSE("GPL");
 476
 477 static int __init mirred_init_module(void)
 478 {
 479         int err = register_netdevice_notifier(&mirred_device_notifier);
 480         if (err)
 481                 return err;
 482
 483         pr_info("Mirror/redirect action on\n");
 484         err = tcf_register_action(&act_mirred_ops, &mirred_net_ops);
 485         if (err)
 486                 unregister_netdevice_notifier(&mirred_device_notifier);
 487
 488         return err;
 489 }
 490
 491 static void __exit mirred_cleanup_module(void)
 492 {
 493         tcf_unregister_action(&act_mirred_ops, &mirred_net_ops);
 494         unregister_netdevice_notifier(&mirred_device_notifier);
 495 }
 496
 497 module_init(mirred_init_module);
 498 module_exit(mirred_cleanup_module);