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