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