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 <net/net_namespace.h>
  25 #include <net/netlink.h>
  26 #include <net/pkt_sched.h>
  27 #include <linux/tc_act/tc_mirred.h>
  28 #include <net/tc_act/tc_mirred.h>
  29
  30 #include <linux/if_arp.h>
  31
  32 #define MIRRED_TAB_MASK     7
  33 static LIST_HEAD(mirred_list);
  34 static DEFINE_SPINLOCK(mirred_list_lock);
  35
  36 static void tcf_mirred_release(struct tc_action *a, int bind)
  37 {
  38         struct tcf_mirred *m = to_mirred(a);
  39         struct net_device *dev;
  40
  41         /* We could be called either in a RCU callback or with RTNL lock held. */
  42         spin_lock_bh(&mirred_list_lock);
  43         list_del(&m->tcfm_list);
  44         dev = rcu_dereference_protected(m->tcfm_dev, 1);
  45         if (dev)
  46                 dev_put(dev);
  47         spin_unlock_bh(&mirred_list_lock);
  48 }
  49
  50 static const struct nla_policy mirred_policy[TCA_MIRRED_MAX + 1] = {
  51         [TCA_MIRRED_PARMS]      = { .len = sizeof(struct tc_mirred) },
  52 };
  53
  54 static int mirred_net_id;
  55
  56 static int tcf_mirred_init(struct net *net, struct nlattr *nla,
  57                            struct nlattr *est, struct tc_action *a, int ovr,
  58                            int bind)
  59 {
  60         struct tc_action_net *tn = net_generic(net, mirred_net_id);
  61         struct nlattr *tb[TCA_MIRRED_MAX + 1];
  62         struct tc_mirred *parm;
  63         struct tcf_mirred *m;
  64         struct net_device *dev;
  65         int ret, ok_push = 0;
  66         bool exists = false;
  67
  68         if (nla == NULL)
  69                 return -EINVAL;
  70         ret = nla_parse_nested(tb, TCA_MIRRED_MAX, nla, mirred_policy);
  71         if (ret < 0)
  72                 return ret;
  73         if (tb[TCA_MIRRED_PARMS] == NULL)
  74                 return -EINVAL;
  75         parm = nla_data(tb[TCA_MIRRED_PARMS]);
  76
  77         exists = tcf_hash_check(tn, parm->index, a, bind);
  78         if (exists && bind)
  79                 return 0;
  80
  81         switch (parm->eaction) {
  82         case TCA_EGRESS_MIRROR:
  83         case TCA_EGRESS_REDIR:
  84                 break;
  85         default:
  86                 if (exists)
  87                         tcf_hash_release(a, bind);
  88                 return -EINVAL;
  89         }
  90         if (parm->ifindex) {
  91                 dev = __dev_get_by_index(net, parm->ifindex);
  92                 if (dev == NULL) {
  93                         if (exists)
  94                                 tcf_hash_release(a, bind);
  95                         return -ENODEV;
  96                 }
  97                 switch (dev->type) {
  98                 case ARPHRD_TUNNEL:
  99                 case ARPHRD_TUNNEL6:
 100                 case ARPHRD_SIT:
 101                 case ARPHRD_IPGRE:
 102                 case ARPHRD_VOID:
 103                 case ARPHRD_NONE:
 104                         ok_push = 0;
 105                         break;
 106                 default:
 107                         ok_push = 1;
 108                         break;
 109                 }
 110         } else {
 111                 dev = NULL;
 112         }
 113
 114         if (!exists) {
 115                 if (dev == NULL)
 116                         return -EINVAL;
 117                 ret = tcf_hash_create(tn, parm->index, est, a,
 118                                       sizeof(*m), bind, true);
 119                 if (ret)
 120                         return ret;
 121                 ret = ACT_P_CREATED;
 122         } else {
 123                 tcf_hash_release(a, bind);
 124                 if (!ovr)
 125                         return -EEXIST;
 126         }
 127         m = to_mirred(a);
 128
 129         ASSERT_RTNL();
 130         m->tcf_action = parm->action;
 131         m->tcfm_eaction = parm->eaction;
 132         if (dev != NULL) {
 133                 m->tcfm_ifindex = parm->ifindex;
 134                 if (ret != ACT_P_CREATED)
 135                         dev_put(rcu_dereference_protected(m->tcfm_dev, 1));
 136                 dev_hold(dev);
 137                 rcu_assign_pointer(m->tcfm_dev, dev);
 138                 m->tcfm_ok_push = ok_push;
 139         }
 140
 141         if (ret == ACT_P_CREATED) {
 142                 spin_lock_bh(&mirred_list_lock);
 143                 list_add(&m->tcfm_list, &mirred_list);
 144                 spin_unlock_bh(&mirred_list_lock);
 145                 tcf_hash_insert(tn, a);
 146         }
 147
 148         return ret;
 149 }
 150
 151 static int tcf_mirred(struct sk_buff *skb, const struct tc_action *a,
 152                       struct tcf_result *res)
 153 {
 154         struct tcf_mirred *m = a->priv;
 155         struct net_device *dev;
 156         struct sk_buff *skb2;
 157         int retval, err;
 158         u32 at;
 159
 160         tcf_lastuse_update(&m->tcf_tm);
 161         bstats_cpu_update(this_cpu_ptr(m->common.cpu_bstats), skb);
 162
 163         rcu_read_lock();
 164         retval = READ_ONCE(m->tcf_action);
 165         dev = rcu_dereference(m->tcfm_dev);
 166         if (unlikely(!dev)) {
 167                 pr_notice_once("tc mirred: target device is gone\n");
 168                 goto out;
 169         }
 170
 171         if (unlikely(!(dev->flags & IFF_UP))) {
 172                 net_notice_ratelimited("tc mirred to Houston: device %s is down\n",
 173                                        dev->name);
 174                 goto out;
 175         }
 176
 177         at = G_TC_AT(skb->tc_verd);
 178         skb2 = skb_clone(skb, GFP_ATOMIC);
 179         if (!skb2)
 180                 goto out;
 181
 182         if (!(at & AT_EGRESS)) {
 183                 if (m->tcfm_ok_push)
 184                         skb_push(skb2, skb->mac_len);
 185         }
 186
 187         /* mirror is always swallowed */
 188         if (m->tcfm_eaction != TCA_EGRESS_MIRROR)
 189                 skb2->tc_verd = SET_TC_FROM(skb2->tc_verd, at);
 190
 191         skb2->skb_iif = skb->dev->ifindex;
 192         skb2->dev = dev;
 193         err = dev_queue_xmit(skb2);
 194
 195         if (err) {
 196 out:
 197                 qstats_overlimit_inc(this_cpu_ptr(m->common.cpu_qstats));
 198                 if (m->tcfm_eaction != TCA_EGRESS_MIRROR)
 199                         retval = TC_ACT_SHOT;
 200         }
 201         rcu_read_unlock();
 202
 203         return retval;
 204 }
 205
 206 static int tcf_mirred_dump(struct sk_buff *skb, struct tc_action *a, int bind, int ref)
 207 {
 208         unsigned char *b = skb_tail_pointer(skb);
 209         struct tcf_mirred *m = a->priv;
 210         struct tc_mirred opt = {
 211                 .index   = m->tcf_index,
 212                 .action  = m->tcf_action,
 213                 .refcnt  = m->tcf_refcnt - ref,
 214                 .bindcnt = m->tcf_bindcnt - bind,
 215                 .eaction = m->tcfm_eaction,
 216                 .ifindex = m->tcfm_ifindex,
 217         };
 218         struct tcf_t t;
 219
 220         if (nla_put(skb, TCA_MIRRED_PARMS, sizeof(opt), &opt))
 221                 goto nla_put_failure;
 222
 223         tcf_tm_dump(&t, &m->tcf_tm);
 224         if (nla_put_64bit(skb, TCA_MIRRED_TM, sizeof(t), &t, TCA_MIRRED_PAD))
 225                 goto nla_put_failure;
 226         return skb->len;
 227
 228 nla_put_failure:
 229         nlmsg_trim(skb, b);
 230         return -1;
 231 }
 232
 233 static int tcf_mirred_walker(struct net *net, struct sk_buff *skb,
 234                              struct netlink_callback *cb, int type,
 235                              struct tc_action *a)
 236 {
 237         struct tc_action_net *tn = net_generic(net, mirred_net_id);
 238
 239         return tcf_generic_walker(tn, skb, cb, type, a);
 240 }
 241
 242 static int tcf_mirred_search(struct net *net, struct tc_action *a, u32 index)
 243 {
 244         struct tc_action_net *tn = net_generic(net, mirred_net_id);
 245
 246         return tcf_hash_search(tn, a, index);
 247 }
 248
 249 static int mirred_device_event(struct notifier_block *unused,
 250                                unsigned long event, void *ptr)
 251 {
 252         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 253         struct tcf_mirred *m;
 254
 255         ASSERT_RTNL();
 256         if (event == NETDEV_UNREGISTER) {
 257                 spin_lock_bh(&mirred_list_lock);
 258                 list_for_each_entry(m, &mirred_list, tcfm_list) {
 259                         if (rcu_access_pointer(m->tcfm_dev) == dev) {
 260                                 dev_put(dev);
 261                                 /* Note : no rcu grace period necessary, as
 262                                  * net_device are already rcu protected.
 263                                  */
 264                                 RCU_INIT_POINTER(m->tcfm_dev, NULL);
 265                         }
 266                 }
 267                 spin_unlock_bh(&mirred_list_lock);
 268         }
 269
 270         return NOTIFY_DONE;
 271 }
 272
 273 static struct notifier_block mirred_device_notifier = {
 274         .notifier_call = mirred_device_event,
 275 };
 276
 277 static struct tc_action_ops act_mirred_ops = {
 278         .kind           =       "mirred",
 279         .type           =       TCA_ACT_MIRRED,
 280         .owner          =       THIS_MODULE,
 281         .act            =       tcf_mirred,
 282         .dump           =       tcf_mirred_dump,
 283         .cleanup        =       tcf_mirred_release,
 284         .init           =       tcf_mirred_init,
 285         .walk           =       tcf_mirred_walker,
 286         .lookup         =       tcf_mirred_search,
 287 };
 288
 289 static __net_init int mirred_init_net(struct net *net)
 290 {
 291         struct tc_action_net *tn = net_generic(net, mirred_net_id);
 292
 293         return tc_action_net_init(tn, &act_mirred_ops, MIRRED_TAB_MASK);
 294 }
 295
 296 static void __net_exit mirred_exit_net(struct net *net)
 297 {
 298         struct tc_action_net *tn = net_generic(net, mirred_net_id);
 299
 300         tc_action_net_exit(tn);
 301 }
 302
 303 static struct pernet_operations mirred_net_ops = {
 304         .init = mirred_init_net,
 305         .exit = mirred_exit_net,
 306         .id   = &mirred_net_id,
 307         .size = sizeof(struct tc_action_net),
 308 };
 309
 310 MODULE_AUTHOR("Jamal Hadi Salim(2002)");
 311 MODULE_DESCRIPTION("Device Mirror/redirect actions");
 312 MODULE_LICENSE("GPL");
 313
 314 static int __init mirred_init_module(void)
 315 {
 316         int err = register_netdevice_notifier(&mirred_device_notifier);
 317         if (err)
 318                 return err;
 319
 320         pr_info("Mirror/redirect action on\n");
 321         return tcf_register_action(&act_mirred_ops, &mirred_net_ops);
 322 }
 323
 324 static void __exit mirred_cleanup_module(void)
 325 {
 326         tcf_unregister_action(&act_mirred_ops, &mirred_net_ops);
 327         unregister_netdevice_notifier(&mirred_device_notifier);
 328 }
 329
 330 module_init(mirred_init_module);
 331 module_exit(mirred_cleanup_module);