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 static LIST_HEAD(mirred_list);
  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 void tcf_mirred_release(struct tc_action *a)
  53 {
  54         struct tcf_mirred *m = to_mirred(a);
  55         struct net_device *dev;
  56
  57         list_del(&m->tcfm_list);
  58         dev = rtnl_dereference(m->tcfm_dev);
  59         if (dev)
  60                 dev_put(dev);
  61 }
  62
  63 static const struct nla_policy mirred_policy[TCA_MIRRED_MAX + 1] = {
  64         [TCA_MIRRED_PARMS]      = { .len = sizeof(struct tc_mirred) },
  65 };
  66
  67 static unsigned int mirred_net_id;
  68 static struct tc_action_ops act_mirred_ops;
  69
  70 static int tcf_mirred_init(struct net *net, struct nlattr *nla,
  71                            struct nlattr *est, struct tc_action **a,
  72                            int ovr, int bind, bool rtnl_held,
  73                            struct netlink_ext_ack *extack)
  74 {
  75         struct tc_action_net *tn = net_generic(net, mirred_net_id);
  76         struct nlattr *tb[TCA_MIRRED_MAX + 1];
  77         bool mac_header_xmit = false;
  78         struct tc_mirred *parm;
  79         struct tcf_mirred *m;
  80         struct net_device *dev;
  81         bool exists = false;
  82         int ret, err;
  83
  84         if (!nla) {
  85                 NL_SET_ERR_MSG_MOD(extack, "Mirred requires attributes to be passed");
  86                 return -EINVAL;
  87         }
  88         ret = nla_parse_nested(tb, TCA_MIRRED_MAX, nla, mirred_policy, extack);
  89         if (ret < 0)
  90                 return ret;
  91         if (!tb[TCA_MIRRED_PARMS]) {
  92                 NL_SET_ERR_MSG_MOD(extack, "Missing required mirred parameters");
  93                 return -EINVAL;
  94         }
  95         parm = nla_data(tb[TCA_MIRRED_PARMS]);
  96
  97         err = tcf_idr_check_alloc(tn, &parm->index, a, bind);
  98         if (err < 0)
  99                 return err;
 100         exists = err;
 101         if (exists && bind)
 102                 return 0;
 103
 104         switch (parm->eaction) {
 105         case TCA_EGRESS_MIRROR:
 106         case TCA_EGRESS_REDIR:
 107         case TCA_INGRESS_REDIR:
 108         case TCA_INGRESS_MIRROR:
 109                 break;
 110         default:
 111                 if (exists)
 112                         tcf_idr_release(*a, bind);
 113                 else
 114                         tcf_idr_cleanup(tn, parm->index);
 115                 NL_SET_ERR_MSG_MOD(extack, "Unknown mirred option");
 116                 return -EINVAL;
 117         }
 118         if (parm->ifindex) {
 119                 dev = __dev_get_by_index(net, parm->ifindex);
 120                 if (dev == NULL) {
 121                         if (exists)
 122                                 tcf_idr_release(*a, bind);
 123                         else
 124                                 tcf_idr_cleanup(tn, parm->index);
 125                         return -ENODEV;
 126                 }
 127                 mac_header_xmit = dev_is_mac_header_xmit(dev);
 128         } else {
 129                 dev = NULL;
 130         }
 131
 132         if (!exists) {
 133                 if (!dev) {
 134                         tcf_idr_cleanup(tn, parm->index);
 135                         NL_SET_ERR_MSG_MOD(extack, "Specified device does not exist");
 136                         return -EINVAL;
 137                 }
 138                 ret = tcf_idr_create(tn, parm->index, est, a,
 139                                      &act_mirred_ops, bind, true);
 140                 if (ret) {
 141                         tcf_idr_cleanup(tn, parm->index);
 142                         return ret;
 143                 }
 144                 ret = ACT_P_CREATED;
 145         } else if (!ovr) {
 146                 tcf_idr_release(*a, bind);
 147                 return -EEXIST;
 148         }
 149         m = to_mirred(*a);
 150
 151         ASSERT_RTNL();
 152         m->tcf_action = parm->action;
 153         m->tcfm_eaction = parm->eaction;
 154         if (dev != NULL) {
 155                 if (ret != ACT_P_CREATED)
 156                         dev_put(rcu_dereference_protected(m->tcfm_dev, 1));
 157                 dev_hold(dev);
 158                 rcu_assign_pointer(m->tcfm_dev, dev);
 159                 m->tcfm_mac_header_xmit = mac_header_xmit;
 160         }
 161
 162         if (ret == ACT_P_CREATED) {
 163                 list_add(&m->tcfm_list, &mirred_list);
 164                 tcf_idr_insert(tn, *a);
 165         }
 166
 167         return ret;
 168 }
 169
 170 static int tcf_mirred(struct sk_buff *skb, const struct tc_action *a,
 171                       struct tcf_result *res)
 172 {
 173         struct tcf_mirred *m = to_mirred(a);
 174         bool m_mac_header_xmit;
 175         struct net_device *dev;
 176         struct sk_buff *skb2;
 177         int retval, err = 0;
 178         int m_eaction;
 179         int mac_len;
 180
 181         tcf_lastuse_update(&m->tcf_tm);
 182         bstats_cpu_update(this_cpu_ptr(m->common.cpu_bstats), skb);
 183
 184         rcu_read_lock();
 185         m_mac_header_xmit = READ_ONCE(m->tcfm_mac_header_xmit);
 186         m_eaction = READ_ONCE(m->tcfm_eaction);
 187         retval = READ_ONCE(m->tcf_action);
 188         dev = rcu_dereference(m->tcfm_dev);
 189         if (unlikely(!dev)) {
 190                 pr_notice_once("tc mirred: target device is gone\n");
 191                 goto out;
 192         }
 193
 194         if (unlikely(!(dev->flags & IFF_UP))) {
 195                 net_notice_ratelimited("tc mirred to Houston: device %s is down\n",
 196                                        dev->name);
 197                 goto out;
 198         }
 199
 200         skb2 = skb_clone(skb, GFP_ATOMIC);
 201         if (!skb2)
 202                 goto out;
 203
 204         /* If action's target direction differs than filter's direction,
 205          * and devices expect a mac header on xmit, then mac push/pull is
 206          * needed.
 207          */
 208         if (skb_at_tc_ingress(skb) != tcf_mirred_act_wants_ingress(m_eaction) &&
 209             m_mac_header_xmit) {
 210                 if (!skb_at_tc_ingress(skb)) {
 211                         /* caught at egress, act ingress: pull mac */
 212                         mac_len = skb_network_header(skb) - skb_mac_header(skb);
 213                         skb_pull_rcsum(skb2, mac_len);
 214                 } else {
 215                         /* caught at ingress, act egress: push mac */
 216                         skb_push_rcsum(skb2, skb->mac_len);
 217                 }
 218         }
 219
 220         /* mirror is always swallowed */
 221         if (tcf_mirred_is_act_redirect(m_eaction)) {
 222                 skb2->tc_redirected = 1;
 223                 skb2->tc_from_ingress = skb2->tc_at_ingress;
 224         }
 225
 226         skb2->skb_iif = skb->dev->ifindex;
 227         skb2->dev = dev;
 228         if (!tcf_mirred_act_wants_ingress(m_eaction))
 229                 err = dev_queue_xmit(skb2);
 230         else
 231                 err = netif_receive_skb(skb2);
 232
 233         if (err) {
 234 out:
 235                 qstats_overlimit_inc(this_cpu_ptr(m->common.cpu_qstats));
 236                 if (tcf_mirred_is_act_redirect(m_eaction))
 237                         retval = TC_ACT_SHOT;
 238         }
 239         rcu_read_unlock();
 240
 241         return retval;
 242 }
 243
 244 static void tcf_stats_update(struct tc_action *a, u64 bytes, u32 packets,
 245                              u64 lastuse)
 246 {
 247         struct tcf_mirred *m = to_mirred(a);
 248         struct tcf_t *tm = &m->tcf_tm;
 249
 250         _bstats_cpu_update(this_cpu_ptr(a->cpu_bstats), bytes, packets);
 251         tm->lastuse = max_t(u64, tm->lastuse, lastuse);
 252 }
 253
 254 static int tcf_mirred_dump(struct sk_buff *skb, struct tc_action *a, int bind,
 255                            int ref)
 256 {
 257         unsigned char *b = skb_tail_pointer(skb);
 258         struct tcf_mirred *m = to_mirred(a);
 259         struct net_device *dev = rtnl_dereference(m->tcfm_dev);
 260         struct tc_mirred opt = {
 261                 .index   = m->tcf_index,
 262                 .action  = m->tcf_action,
 263                 .refcnt  = refcount_read(&m->tcf_refcnt) - ref,
 264                 .bindcnt = atomic_read(&m->tcf_bindcnt) - bind,
 265                 .eaction = m->tcfm_eaction,
 266                 .ifindex = dev ? dev->ifindex : 0,
 267         };
 268         struct tcf_t t;
 269
 270         if (nla_put(skb, TCA_MIRRED_PARMS, sizeof(opt), &opt))
 271                 goto nla_put_failure;
 272
 273         tcf_tm_dump(&t, &m->tcf_tm);
 274         if (nla_put_64bit(skb, TCA_MIRRED_TM, sizeof(t), &t, TCA_MIRRED_PAD))
 275                 goto nla_put_failure;
 276         return skb->len;
 277
 278 nla_put_failure:
 279         nlmsg_trim(skb, b);
 280         return -1;
 281 }
 282
 283 static int tcf_mirred_walker(struct net *net, struct sk_buff *skb,
 284                              struct netlink_callback *cb, int type,
 285                              const struct tc_action_ops *ops,
 286                              struct netlink_ext_ack *extack)
 287 {
 288         struct tc_action_net *tn = net_generic(net, mirred_net_id);
 289
 290         return tcf_generic_walker(tn, skb, cb, type, ops, extack);
 291 }
 292
 293 static int tcf_mirred_search(struct net *net, struct tc_action **a, u32 index,
 294                              struct netlink_ext_ack *extack)
 295 {
 296         struct tc_action_net *tn = net_generic(net, mirred_net_id);
 297
 298         return tcf_idr_search(tn, a, index);
 299 }
 300
 301 static int mirred_device_event(struct notifier_block *unused,
 302                                unsigned long event, void *ptr)
 303 {
 304         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 305         struct tcf_mirred *m;
 306
 307         ASSERT_RTNL();
 308         if (event == NETDEV_UNREGISTER) {
 309                 list_for_each_entry(m, &mirred_list, tcfm_list) {
 310                         if (rcu_access_pointer(m->tcfm_dev) == dev) {
 311                                 dev_put(dev);
 312                                 /* Note : no rcu grace period necessary, as
 313                                  * net_device are already rcu protected.
 314                                  */
 315                                 RCU_INIT_POINTER(m->tcfm_dev, NULL);
 316                         }
 317                 }
 318         }
 319
 320         return NOTIFY_DONE;
 321 }
 322
 323 static struct notifier_block mirred_device_notifier = {
 324         .notifier_call = mirred_device_event,
 325 };
 326
 327 static struct net_device *tcf_mirred_get_dev(const struct tc_action *a)
 328 {
 329         struct tcf_mirred *m = to_mirred(a);
 330
 331         return rtnl_dereference(m->tcfm_dev);
 332 }
 333
 334 static int tcf_mirred_delete(struct net *net, u32 index)
 335 {
 336         struct tc_action_net *tn = net_generic(net, mirred_net_id);
 337
 338         return tcf_idr_delete_index(tn, index);
 339 }
 340
 341 static struct tc_action_ops act_mirred_ops = {
 342         .kind           =       "mirred",
 343         .type           =       TCA_ACT_MIRRED,
 344         .owner          =       THIS_MODULE,
 345         .act            =       tcf_mirred,
 346         .stats_update   =       tcf_stats_update,
 347         .dump           =       tcf_mirred_dump,
 348         .cleanup        =       tcf_mirred_release,
 349         .init           =       tcf_mirred_init,
 350         .walk           =       tcf_mirred_walker,
 351         .lookup         =       tcf_mirred_search,
 352         .size           =       sizeof(struct tcf_mirred),
 353         .get_dev        =       tcf_mirred_get_dev,
 354         .delete         =       tcf_mirred_delete,
 355 };
 356
 357 static __net_init int mirred_init_net(struct net *net)
 358 {
 359         struct tc_action_net *tn = net_generic(net, mirred_net_id);
 360
 361         return tc_action_net_init(tn, &act_mirred_ops);
 362 }
 363
 364 static void __net_exit mirred_exit_net(struct list_head *net_list)
 365 {
 366         tc_action_net_exit(net_list, mirred_net_id);
 367 }
 368
 369 static struct pernet_operations mirred_net_ops = {
 370         .init = mirred_init_net,
 371         .exit_batch = mirred_exit_net,
 372         .id   = &mirred_net_id,
 373         .size = sizeof(struct tc_action_net),
 374 };
 375
 376 MODULE_AUTHOR("Jamal Hadi Salim(2002)");
 377 MODULE_DESCRIPTION("Device Mirror/redirect actions");
 378 MODULE_LICENSE("GPL");
 379
 380 static int __init mirred_init_module(void)
 381 {
 382         int err = register_netdevice_notifier(&mirred_device_notifier);
 383         if (err)
 384                 return err;
 385
 386         pr_info("Mirror/redirect action on\n");
 387         return tcf_register_action(&act_mirred_ops, &mirred_net_ops);
 388 }
 389
 390 static void __exit mirred_cleanup_module(void)
 391 {
 392         tcf_unregister_action(&act_mirred_ops, &mirred_net_ops);
 393         unregister_netdevice_notifier(&mirred_device_notifier);
 394 }
 395
 396 module_init(mirred_init_module);
 397 module_exit(mirred_cleanup_module);