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, struct netlink_ext_ack *extack)
  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) {
  84                 NL_SET_ERR_MSG_MOD(extack, "Mirred requires attributes to be passed");
  85                 return -EINVAL;
  86         }
  87         ret = nla_parse_nested(tb, TCA_MIRRED_MAX, nla, mirred_policy, extack);
  88         if (ret < 0)
  89                 return ret;
  90         if (!tb[TCA_MIRRED_PARMS]) {
  91                 NL_SET_ERR_MSG_MOD(extack, "Missing required mirred parameters");
  92                 return -EINVAL;
  93         }
  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                 NL_SET_ERR_MSG_MOD(extack, "Unknown mirred option");
 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_idr_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) {
 126                         NL_SET_ERR_MSG_MOD(extack, "Specified device does not exist");
 127                         return -EINVAL;
 128                 }
 129                 ret = tcf_idr_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_idr_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                 if (ret != ACT_P_CREATED)
 146                         dev_put(rcu_dereference_protected(m->tcfm_dev, 1));
 147                 dev_hold(dev);
 148                 rcu_assign_pointer(m->tcfm_dev, dev);
 149                 m->tcfm_mac_header_xmit = mac_header_xmit;
 150         }
 151
 152         if (ret == ACT_P_CREATED) {
 153                 list_add(&m->tcfm_list, &mirred_list);
 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 = max_t(u64, 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 net_device *dev = rtnl_dereference(m->tcfm_dev);
 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 = dev ? dev->ifindex : 0,
 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                              struct netlink_ext_ack *extack)
 277 {
 278         struct tc_action_net *tn = net_generic(net, mirred_net_id);
 279
 280         return tcf_generic_walker(tn, skb, cb, type, ops, extack);
 281 }
 282
 283 static int tcf_mirred_search(struct net *net, struct tc_action **a, u32 index,
 284                              struct netlink_ext_ack *extack)
 285 {
 286         struct tc_action_net *tn = net_generic(net, mirred_net_id);
 287
 288         return tcf_idr_search(tn, a, index);
 289 }
 290
 291 static int mirred_device_event(struct notifier_block *unused,
 292                                unsigned long event, void *ptr)
 293 {
 294         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 295         struct tcf_mirred *m;
 296
 297         ASSERT_RTNL();
 298         if (event == NETDEV_UNREGISTER) {
 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         }
 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 struct net_device *tcf_mirred_get_dev(const struct tc_action *a)
 318 {
 319         struct tcf_mirred *m = to_mirred(a);
 320
 321         return rtnl_dereference(m->tcfm_dev);
 322 }
 323
 324 static struct tc_action_ops act_mirred_ops = {
 325         .kind           =       "mirred",
 326         .type           =       TCA_ACT_MIRRED,
 327         .owner          =       THIS_MODULE,
 328         .act            =       tcf_mirred,
 329         .stats_update   =       tcf_stats_update,
 330         .dump           =       tcf_mirred_dump,
 331         .cleanup        =       tcf_mirred_release,
 332         .init           =       tcf_mirred_init,
 333         .walk           =       tcf_mirred_walker,
 334         .lookup         =       tcf_mirred_search,
 335         .size           =       sizeof(struct tcf_mirred),
 336         .get_dev        =       tcf_mirred_get_dev,
 337 };
 338
 339 static __net_init int mirred_init_net(struct net *net)
 340 {
 341         struct tc_action_net *tn = net_generic(net, mirred_net_id);
 342
 343         return tc_action_net_init(tn, &act_mirred_ops);
 344 }
 345
 346 static void __net_exit mirred_exit_net(struct list_head *net_list)
 347 {
 348         tc_action_net_exit(net_list, mirred_net_id);
 349 }
 350
 351 static struct pernet_operations mirred_net_ops = {
 352         .init = mirred_init_net,
 353         .exit_batch = mirred_exit_net,
 354         .id   = &mirred_net_id,
 355         .size = sizeof(struct tc_action_net),
 356 };
 357
 358 MODULE_AUTHOR("Jamal Hadi Salim(2002)");
 359 MODULE_DESCRIPTION("Device Mirror/redirect actions");
 360 MODULE_LICENSE("GPL");
 361
 362 static int __init mirred_init_module(void)
 363 {
 364         int err = register_netdevice_notifier(&mirred_device_notifier);
 365         if (err)
 366                 return err;
 367
 368         pr_info("Mirror/redirect action on\n");
 369         return tcf_register_action(&act_mirred_ops, &mirred_net_ops);
 370 }
 371
 372 static void __exit mirred_cleanup_module(void)
 373 {
 374         tcf_unregister_action(&act_mirred_ops, &mirred_net_ops);
 375         unregister_netdevice_notifier(&mirred_device_notifier);
 376 }
 377
 378 module_init(mirred_init_module);
 379 module_exit(mirred_cleanup_module);