net/sched/act_mirred.c

   1 /*
   2  * net/sched/act_mirred.c       packet mirroring and redirect actions
   3  *
   4  *              This program is free software; you can redistribute it and/or
   5  *              modify it under the terms of the GNU General Public License
   6  *              as published by the Free Software Foundation; either version
   7  *              2 of the License, or (at your option) any later version.
   8  *
   9  * Authors:     Jamal Hadi Salim (2002-4)
  10  *
  11  * TODO: Add ingress support (and socket redirect support)
  12  *
  13  */
  14
  15 #include <linux/types.h>
  16 #include <linux/kernel.h>
  17 #include <linux/string.h>
  18 #include <linux/errno.h>
  19 #include <linux/skbuff.h>
  20 #include <linux/rtnetlink.h>
  21 #include <linux/module.h>
  22 #include <linux/init.h>
  23 #include <linux/gfp.h>
  24 #include <linux/if_arp.h>
  25 #include <net/net_namespace.h>
  26 #include <net/netlink.h>
  27 #include <net/pkt_sched.h>
  28 #include <linux/tc_act/tc_mirred.h>
  29 #include <net/tc_act/tc_mirred.h>
  30
  31 #define MIRRED_TAB_MASK     7
  32 static LIST_HEAD(mirred_list);
  33 static DEFINE_SPINLOCK(mirred_list_lock);
  34
  35 static bool tcf_mirred_is_act_redirect(int action)
  36 {
  37         return action == TCA_EGRESS_REDIR || action == TCA_INGRESS_REDIR;
  38 }
  39
  40 static bool tcf_mirred_act_wants_ingress(int action)
  41 {
  42         switch (action) {
  43         case TCA_EGRESS_REDIR:
  44         case TCA_EGRESS_MIRROR:
  45                 return false;
  46         case TCA_INGRESS_REDIR:
  47         case TCA_INGRESS_MIRROR:
  48                 return true;
  49         default:
  50                 BUG();
  51         }
  52 }
  53
  54 static void tcf_mirred_release(struct tc_action *a, int bind)
  55 {
  56         struct tcf_mirred *m = to_mirred(a);
  57         struct net_device *dev;
  58
  59         /* We could be called either in a RCU callback or with RTNL lock held. */
  60         spin_lock_bh(&mirred_list_lock);
  61         list_del(&m->tcfm_list);
  62         dev = rcu_dereference_protected(m->tcfm_dev, 1);
  63         if (dev)
  64                 dev_put(dev);
  65         spin_unlock_bh(&mirred_list_lock);
  66 }
  67
  68 static const struct nla_policy mirred_policy[TCA_MIRRED_MAX + 1] = {
  69         [TCA_MIRRED_PARMS]      = { .len = sizeof(struct tc_mirred) },
  70 };
  71
  72 static unsigned int mirred_net_id;
  73 static struct tc_action_ops act_mirred_ops;
  74
  75 static int tcf_mirred_init(struct net *net, struct nlattr *nla,
  76                            struct nlattr *est, struct tc_action **a, int ovr,
  77                            int bind)
  78 {
  79         struct tc_action_net *tn = net_generic(net, mirred_net_id);
  80         struct nlattr *tb[TCA_MIRRED_MAX + 1];
  81         bool mac_header_xmit = false;
  82         struct tc_mirred *parm;
  83         struct tcf_mirred *m;
  84         struct net_device *dev;
  85         bool exists = false;
  86         int ret;
  87
  88         if (nla == NULL)
  89                 return -EINVAL;
  90         ret = nla_parse_nested(tb, TCA_MIRRED_MAX, nla, mirred_policy);
  91         if (ret < 0)
  92                 return ret;
  93         if (tb[TCA_MIRRED_PARMS] == NULL)
  94                 return -EINVAL;
  95         parm = nla_data(tb[TCA_MIRRED_PARMS]);
  96
  97         exists = tcf_hash_check(tn, parm->index, a, bind);
  98         if (exists && bind)
  99                 return 0;
 100
 101         switch (parm->eaction) {
 102         case TCA_EGRESS_MIRROR:
 103         case TCA_EGRESS_REDIR:
 104         case TCA_INGRESS_REDIR:
 105         case TCA_INGRESS_MIRROR:
 106                 break;
 107         default:
 108                 if (exists)
 109                         tcf_hash_release(*a, bind);
 110                 return -EINVAL;
 111         }
 112         if (parm->ifindex) {
 113                 dev = __dev_get_by_index(net, parm->ifindex);
 114                 if (dev == NULL) {
 115                         if (exists)
 116                                 tcf_hash_release(*a, bind);
 117                         return -ENODEV;
 118                 }
 119                 mac_header_xmit = dev_is_mac_header_xmit(dev);
 120         } else {
 121                 dev = NULL;
 122         }
 123
 124         if (!exists) {
 125                 if (dev == NULL)
 126                         return -EINVAL;
 127                 ret = tcf_hash_create(tn, parm->index, est, a,
 128                                       &act_mirred_ops, bind, true);
 129                 if (ret)
 130                         return ret;
 131                 ret = ACT_P_CREATED;
 132         } else {
 133                 tcf_hash_release(*a, bind);
 134                 if (!ovr)
 135                         return -EEXIST;
 136         }
 137         m = to_mirred(*a);
 138
 139         ASSERT_RTNL();
 140         m->tcf_action = parm->action;
 141         m->tcfm_eaction = parm->eaction;
 142         if (dev != NULL) {
 143                 m->tcfm_ifindex = parm->ifindex;
 144                 if (ret != ACT_P_CREATED)
 145                         dev_put(rcu_dereference_protected(m->tcfm_dev, 1));
 146                 dev_hold(dev);
 147                 rcu_assign_pointer(m->tcfm_dev, dev);
 148                 m->tcfm_mac_header_xmit = mac_header_xmit;
 149         }
 150
 151         if (ret == ACT_P_CREATED) {
 152                 spin_lock_bh(&mirred_list_lock);
 153                 list_add(&m->tcfm_list, &mirred_list);
 154                 spin_unlock_bh(&mirred_list_lock);
 155                 tcf_hash_insert(tn, *a);
 156         }
 157
 158         return ret;
 159 }
 160
 161 static int tcf_mirred(struct sk_buff *skb, const struct tc_action *a,
 162                       struct tcf_result *res)
 163 {
 164         struct tcf_mirred *m = to_mirred(a);
 165         bool m_mac_header_xmit;
 166         struct net_device *dev;
 167         struct sk_buff *skb2;
 168         int retval, err = 0;
 169         int m_eaction;
 170         int mac_len;
 171
 172         tcf_lastuse_update(&m->tcf_tm);
 173         bstats_cpu_update(this_cpu_ptr(m->common.cpu_bstats), skb);
 174
 175         rcu_read_lock();
 176         m_mac_header_xmit = READ_ONCE(m->tcfm_mac_header_xmit);
 177         m_eaction = READ_ONCE(m->tcfm_eaction);
 178         retval = READ_ONCE(m->tcf_action);
 179         dev = rcu_dereference(m->tcfm_dev);
 180         if (unlikely(!dev)) {
 181                 pr_notice_once("tc mirred: target device is gone\n");
 182                 goto out;
 183         }
 184
 185         if (unlikely(!(dev->flags & IFF_UP))) {
 186                 net_notice_ratelimited("tc mirred to Houston: device %s is down\n",
 187                                        dev->name);
 188                 goto out;
 189         }
 190
 191         skb2 = skb_clone(skb, GFP_ATOMIC);
 192         if (!skb2)
 193                 goto out;
 194
 195         /* If action's target direction differs than filter's direction,
 196          * and devices expect a mac header on xmit, then mac push/pull is
 197          * needed.
 198          */
 199         if (skb_at_tc_ingress(skb) != tcf_mirred_act_wants_ingress(m_eaction) &&
 200             m_mac_header_xmit) {
 201                 if (!skb_at_tc_ingress(skb)) {
 202                         /* caught at egress, act ingress: pull mac */
 203                         mac_len = skb_network_header(skb) - skb_mac_header(skb);
 204                         skb_pull_rcsum(skb2, mac_len);
 205                 } else {
 206                         /* caught at ingress, act egress: push mac */
 207                         skb_push_rcsum(skb2, skb->mac_len);
 208                 }
 209         }
 210
 211         /* mirror is always swallowed */
 212         if (tcf_mirred_is_act_redirect(m_eaction)) {
 213                 skb2->tc_redirected = 1;
 214                 skb2->tc_from_ingress = skb2->tc_at_ingress;
 215         }
 216
 217         skb2->skb_iif = skb->dev->ifindex;
 218         skb2->dev = dev;
 219         if (!tcf_mirred_act_wants_ingress(m_eaction))
 220                 err = dev_queue_xmit(skb2);
 221         else
 222                 err = netif_receive_skb(skb2);
 223
 224         if (err) {
 225 out:
 226                 qstats_overlimit_inc(this_cpu_ptr(m->common.cpu_qstats));
 227                 if (tcf_mirred_is_act_redirect(m_eaction))
 228                         retval = TC_ACT_SHOT;
 229         }
 230         rcu_read_unlock();
 231
 232         return retval;
 233 }
 234
 235 static void tcf_stats_update(struct tc_action *a, u64 bytes, u32 packets,
 236                              u64 lastuse)
 237 {
 238         struct tcf_mirred *m = to_mirred(a);
 239         struct tcf_t *tm = &m->tcf_tm;
 240
 241         _bstats_cpu_update(this_cpu_ptr(a->cpu_bstats), bytes, packets);
 242         tm->lastuse = lastuse;
 243 }
 244
 245 static int tcf_mirred_dump(struct sk_buff *skb, struct tc_action *a, int bind,
 246                            int ref)
 247 {
 248         unsigned char *b = skb_tail_pointer(skb);
 249         struct tcf_mirred *m = to_mirred(a);
 250         struct tc_mirred opt = {
 251                 .index   = m->tcf_index,
 252                 .action  = m->tcf_action,
 253                 .refcnt  = m->tcf_refcnt - ref,
 254                 .bindcnt = m->tcf_bindcnt - bind,
 255                 .eaction = m->tcfm_eaction,
 256                 .ifindex = m->tcfm_ifindex,
 257         };
 258         struct tcf_t t;
 259
 260         if (nla_put(skb, TCA_MIRRED_PARMS, sizeof(opt), &opt))
 261                 goto nla_put_failure;
 262
 263         tcf_tm_dump(&t, &m->tcf_tm);
 264         if (nla_put_64bit(skb, TCA_MIRRED_TM, sizeof(t), &t, TCA_MIRRED_PAD))
 265                 goto nla_put_failure;
 266         return skb->len;
 267
 268 nla_put_failure:
 269         nlmsg_trim(skb, b);
 270         return -1;
 271 }
 272
 273 static int tcf_mirred_walker(struct net *net, struct sk_buff *skb,
 274                              struct netlink_callback *cb, int type,
 275                              const struct tc_action_ops *ops)
 276 {
 277         struct tc_action_net *tn = net_generic(net, mirred_net_id);
 278
 279         return tcf_generic_walker(tn, skb, cb, type, ops);
 280 }
 281
 282 static int tcf_mirred_search(struct net *net, struct tc_action **a, u32 index)
 283 {
 284         struct tc_action_net *tn = net_generic(net, mirred_net_id);
 285
 286         return tcf_hash_search(tn, a, index);
 287 }
 288
 289 static int mirred_device_event(struct notifier_block *unused,
 290                                unsigned long event, void *ptr)
 291 {
 292         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 293         struct tcf_mirred *m;
 294
 295         ASSERT_RTNL();
 296         if (event == NETDEV_UNREGISTER) {
 297                 spin_lock_bh(&mirred_list_lock);
 298                 list_for_each_entry(m, &mirred_list, tcfm_list) {
 299                         if (rcu_access_pointer(m->tcfm_dev) == dev) {
 300                                 dev_put(dev);
 301                                 /* Note : no rcu grace period necessary, as
 302                                  * net_device are already rcu protected.
 303                                  */
 304                                 RCU_INIT_POINTER(m->tcfm_dev, NULL);
 305                         }
 306                 }
 307                 spin_unlock_bh(&mirred_list_lock);
 308         }
 309
 310         return NOTIFY_DONE;
 311 }
 312
 313 static struct notifier_block mirred_device_notifier = {
 314         .notifier_call = mirred_device_event,
 315 };
 316
 317 static int tcf_mirred_device(const struct tc_action *a, struct net *net,
 318                              struct net_device **mirred_dev)
 319 {
 320         int ifindex = tcf_mirred_ifindex(a);
 321
 322         *mirred_dev = __dev_get_by_index(net, ifindex);
 323         if (!*mirred_dev)
 324                 return -EINVAL;
 325         return 0;
 326 }
 327
 328 static struct tc_action_ops act_mirred_ops = {
 329         .kind           =       "mirred",
 330         .type           =       TCA_ACT_MIRRED,
 331         .owner          =       THIS_MODULE,
 332         .act            =       tcf_mirred,
 333         .stats_update   =       tcf_stats_update,
 334         .dump           =       tcf_mirred_dump,
 335         .cleanup        =       tcf_mirred_release,
 336         .init           =       tcf_mirred_init,
 337         .walk           =       tcf_mirred_walker,
 338         .lookup         =       tcf_mirred_search,
 339         .size           =       sizeof(struct tcf_mirred),
 340         .get_dev        =       tcf_mirred_device,
 341 };
 342
 343 static __net_init int mirred_init_net(struct net *net)
 344 {
 345         struct tc_action_net *tn = net_generic(net, mirred_net_id);
 346
 347         return tc_action_net_init(tn, &act_mirred_ops, MIRRED_TAB_MASK);
 348 }
 349
 350 static void __net_exit mirred_exit_net(struct net *net)
 351 {
 352         struct tc_action_net *tn = net_generic(net, mirred_net_id);
 353
 354         tc_action_net_exit(tn);
 355 }
 356
 357 static struct pernet_operations mirred_net_ops = {
 358         .init = mirred_init_net,
 359         .exit = mirred_exit_net,
 360         .id   = &mirred_net_id,
 361         .size = sizeof(struct tc_action_net),
 362 };
 363
 364 MODULE_AUTHOR("Jamal Hadi Salim(2002)");
 365 MODULE_DESCRIPTION("Device Mirror/redirect actions");
 366 MODULE_LICENSE("GPL");
 367
 368 static int __init mirred_init_module(void)
 369 {
 370         int err = register_netdevice_notifier(&mirred_device_notifier);
 371         if (err)
 372                 return err;
 373
 374         pr_info("Mirror/redirect action on\n");
 375         return tcf_register_action(&act_mirred_ops, &mirred_net_ops);
 376 }
 377
 378 static void __exit mirred_cleanup_module(void)
 379 {
 380         tcf_unregister_action(&act_mirred_ops, &mirred_net_ops);
 381         unregister_netdevice_notifier(&mirred_device_notifier);
 382 }
 383
 384 module_init(mirred_init_module);
 385 module_exit(mirred_cleanup_module);