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