linux/net/sched/act_mirred.c
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   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
  27static LIST_HEAD(mirred_list);
  28static DEFINE_SPINLOCK(mirred_list_lock);
  29
  30#define MIRRED_RECURSION_LIMIT    4
  31static DEFINE_PER_CPU(unsigned int, mirred_rec_level);
  32
  33static bool tcf_mirred_is_act_redirect(int action)
  34{
  35        return action == TCA_EGRESS_REDIR || action == TCA_INGRESS_REDIR;
  36}
  37
  38static 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
  52static 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
  64static 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
  70static 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
  85static const struct nla_policy mirred_policy[TCA_MIRRED_MAX + 1] = {
  86        [TCA_MIRRED_PARMS]      = { .len = sizeof(struct tc_mirred) },
  87};
  88
  89static unsigned int mirred_net_id;
  90static struct tc_action_ops act_mirred_ops;
  91
  92static 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
 199        return ret;
 200put_chain:
 201        if (goto_ch)
 202                tcf_chain_put_by_act(goto_ch);
 203release_idr:
 204        tcf_idr_release(*a, bind);
 205        return err;
 206}
 207
 208static int tcf_mirred_forward(bool want_ingress, struct sk_buff *skb)
 209{
 210        int err;
 211
 212        if (!want_ingress)
 213                err = tcf_dev_queue_xmit(skb, dev_queue_xmit);
 214        else
 215                err = netif_receive_skb(skb);
 216
 217        return err;
 218}
 219
 220static int tcf_mirred_act(struct sk_buff *skb, const struct tc_action *a,
 221                          struct tcf_result *res)
 222{
 223        struct tcf_mirred *m = to_mirred(a);
 224        struct sk_buff *skb2 = skb;
 225        bool m_mac_header_xmit;
 226        struct net_device *dev;
 227        unsigned int rec_level;
 228        int retval, err = 0;
 229        bool use_reinsert;
 230        bool want_ingress;
 231        bool is_redirect;
 232        bool expects_nh;
 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        use_reinsert = skb_at_tc_ingress(skb) && is_redirect &&
 269                       tcf_mirred_can_reinsert(retval);
 270        if (!use_reinsert) {
 271                skb2 = skb_clone(skb, GFP_ATOMIC);
 272                if (!skb2)
 273                        goto out;
 274        }
 275
 276        /* All mirred/redirected skbs should clear previous ct info */
 277        nf_reset_ct(skb2);
 278
 279        want_ingress = tcf_mirred_act_wants_ingress(m_eaction);
 280
 281        expects_nh = want_ingress || !m_mac_header_xmit;
 282        at_nh = skb->data == skb_network_header(skb);
 283        if (at_nh != expects_nh) {
 284                mac_len = skb_at_tc_ingress(skb) ? skb->mac_len :
 285                          skb_network_header(skb) - skb_mac_header(skb);
 286                if (expects_nh) {
 287                        /* target device/action expect data at nh */
 288                        skb_pull_rcsum(skb2, mac_len);
 289                } else {
 290                        /* target device/action expect data at mac */
 291                        skb_push_rcsum(skb2, mac_len);
 292                }
 293        }
 294
 295        skb2->skb_iif = skb->dev->ifindex;
 296        skb2->dev = dev;
 297
 298        /* mirror is always swallowed */
 299        if (is_redirect) {
 300                skb_set_redirected(skb2, skb2->tc_at_ingress);
 301
 302                /* let's the caller reinsert the packet, if possible */
 303                if (use_reinsert) {
 304                        res->ingress = want_ingress;
 305                        err = tcf_mirred_forward(res->ingress, skb);
 306                        if (err)
 307                                tcf_action_inc_overlimit_qstats(&m->common);
 308                        __this_cpu_dec(mirred_rec_level);
 309                        return TC_ACT_CONSUMED;
 310                }
 311        }
 312
 313        err = tcf_mirred_forward(want_ingress, skb2);
 314        if (err) {
 315out:
 316                tcf_action_inc_overlimit_qstats(&m->common);
 317                if (tcf_mirred_is_act_redirect(m_eaction))
 318                        retval = TC_ACT_SHOT;
 319        }
 320        __this_cpu_dec(mirred_rec_level);
 321
 322        return retval;
 323}
 324
 325static void tcf_stats_update(struct tc_action *a, u64 bytes, u64 packets,
 326                             u64 drops, u64 lastuse, bool hw)
 327{
 328        struct tcf_mirred *m = to_mirred(a);
 329        struct tcf_t *tm = &m->tcf_tm;
 330
 331        tcf_action_update_stats(a, bytes, packets, drops, hw);
 332        tm->lastuse = max_t(u64, tm->lastuse, lastuse);
 333}
 334
 335static int tcf_mirred_dump(struct sk_buff *skb, struct tc_action *a, int bind,
 336                           int ref)
 337{
 338        unsigned char *b = skb_tail_pointer(skb);
 339        struct tcf_mirred *m = to_mirred(a);
 340        struct tc_mirred opt = {
 341                .index   = m->tcf_index,
 342                .refcnt  = refcount_read(&m->tcf_refcnt) - ref,
 343                .bindcnt = atomic_read(&m->tcf_bindcnt) - bind,
 344        };
 345        struct net_device *dev;
 346        struct tcf_t t;
 347
 348        spin_lock_bh(&m->tcf_lock);
 349        opt.action = m->tcf_action;
 350        opt.eaction = m->tcfm_eaction;
 351        dev = tcf_mirred_dev_dereference(m);
 352        if (dev)
 353                opt.ifindex = dev->ifindex;
 354
 355        if (nla_put(skb, TCA_MIRRED_PARMS, sizeof(opt), &opt))
 356                goto nla_put_failure;
 357
 358        tcf_tm_dump(&t, &m->tcf_tm);
 359        if (nla_put_64bit(skb, TCA_MIRRED_TM, sizeof(t), &t, TCA_MIRRED_PAD))
 360                goto nla_put_failure;
 361        spin_unlock_bh(&m->tcf_lock);
 362
 363        return skb->len;
 364
 365nla_put_failure:
 366        spin_unlock_bh(&m->tcf_lock);
 367        nlmsg_trim(skb, b);
 368        return -1;
 369}
 370
 371static int tcf_mirred_walker(struct net *net, struct sk_buff *skb,
 372                             struct netlink_callback *cb, int type,
 373                             const struct tc_action_ops *ops,
 374                             struct netlink_ext_ack *extack)
 375{
 376        struct tc_action_net *tn = net_generic(net, mirred_net_id);
 377
 378        return tcf_generic_walker(tn, skb, cb, type, ops, extack);
 379}
 380
 381static int tcf_mirred_search(struct net *net, struct tc_action **a, u32 index)
 382{
 383        struct tc_action_net *tn = net_generic(net, mirred_net_id);
 384
 385        return tcf_idr_search(tn, a, index);
 386}
 387
 388static int mirred_device_event(struct notifier_block *unused,
 389                               unsigned long event, void *ptr)
 390{
 391        struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 392        struct tcf_mirred *m;
 393
 394        ASSERT_RTNL();
 395        if (event == NETDEV_UNREGISTER) {
 396                spin_lock(&mirred_list_lock);
 397                list_for_each_entry(m, &mirred_list, tcfm_list) {
 398                        spin_lock_bh(&m->tcf_lock);
 399                        if (tcf_mirred_dev_dereference(m) == dev) {
 400                                dev_put(dev);
 401                                /* Note : no rcu grace period necessary, as
 402                                 * net_device are already rcu protected.
 403                                 */
 404                                RCU_INIT_POINTER(m->tcfm_dev, NULL);
 405                        }
 406                        spin_unlock_bh(&m->tcf_lock);
 407                }
 408                spin_unlock(&mirred_list_lock);
 409        }
 410
 411        return NOTIFY_DONE;
 412}
 413
 414static struct notifier_block mirred_device_notifier = {
 415        .notifier_call = mirred_device_event,
 416};
 417
 418static void tcf_mirred_dev_put(void *priv)
 419{
 420        struct net_device *dev = priv;
 421
 422        dev_put(dev);
 423}
 424
 425static struct net_device *
 426tcf_mirred_get_dev(const struct tc_action *a,
 427                   tc_action_priv_destructor *destructor)
 428{
 429        struct tcf_mirred *m = to_mirred(a);
 430        struct net_device *dev;
 431
 432        rcu_read_lock();
 433        dev = rcu_dereference(m->tcfm_dev);
 434        if (dev) {
 435                dev_hold(dev);
 436                *destructor = tcf_mirred_dev_put;
 437        }
 438        rcu_read_unlock();
 439
 440        return dev;
 441}
 442
 443static size_t tcf_mirred_get_fill_size(const struct tc_action *act)
 444{
 445        return nla_total_size(sizeof(struct tc_mirred));
 446}
 447
 448static struct tc_action_ops act_mirred_ops = {
 449        .kind           =       "mirred",
 450        .id             =       TCA_ID_MIRRED,
 451        .owner          =       THIS_MODULE,
 452        .act            =       tcf_mirred_act,
 453        .stats_update   =       tcf_stats_update,
 454        .dump           =       tcf_mirred_dump,
 455        .cleanup        =       tcf_mirred_release,
 456        .init           =       tcf_mirred_init,
 457        .walk           =       tcf_mirred_walker,
 458        .lookup         =       tcf_mirred_search,
 459        .get_fill_size  =       tcf_mirred_get_fill_size,
 460        .size           =       sizeof(struct tcf_mirred),
 461        .get_dev        =       tcf_mirred_get_dev,
 462};
 463
 464static __net_init int mirred_init_net(struct net *net)
 465{
 466        struct tc_action_net *tn = net_generic(net, mirred_net_id);
 467
 468        return tc_action_net_init(net, tn, &act_mirred_ops);
 469}
 470
 471static void __net_exit mirred_exit_net(struct list_head *net_list)
 472{
 473        tc_action_net_exit(net_list, mirred_net_id);
 474}
 475
 476static struct pernet_operations mirred_net_ops = {
 477        .init = mirred_init_net,
 478        .exit_batch = mirred_exit_net,
 479        .id   = &mirred_net_id,
 480        .size = sizeof(struct tc_action_net),
 481};
 482
 483MODULE_AUTHOR("Jamal Hadi Salim(2002)");
 484MODULE_DESCRIPTION("Device Mirror/redirect actions");
 485MODULE_LICENSE("GPL");
 486
 487static int __init mirred_init_module(void)
 488{
 489        int err = register_netdevice_notifier(&mirred_device_notifier);
 490        if (err)
 491                return err;
 492
 493        pr_info("Mirror/redirect action on\n");
 494        err = tcf_register_action(&act_mirred_ops, &mirred_net_ops);
 495        if (err)
 496                unregister_netdevice_notifier(&mirred_device_notifier);
 497
 498        return err;
 499}
 500
 501static void __exit mirred_cleanup_module(void)
 502{
 503        tcf_unregister_action(&act_mirred_ops, &mirred_net_ops);
 504        unregister_netdevice_notifier(&mirred_device_notifier);
 505}
 506
 507module_init(mirred_init_module);
 508module_exit(mirred_cleanup_module);
 509