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 tcf_mirred_init(struct net *net, struct nlattr *nla,
  55                            struct nlattr *est, struct tc_action *a, int ovr,
  56                            int bind)
  57 {
  58         struct nlattr *tb[TCA_MIRRED_MAX + 1];
  59         struct tc_mirred *parm;
  60         struct tcf_mirred *m;
  61         struct net_device *dev;
  62         int ret, ok_push = 0;
  63
  64         if (nla == NULL)
  65                 return -EINVAL;
  66         ret = nla_parse_nested(tb, TCA_MIRRED_MAX, nla, mirred_policy);
  67         if (ret < 0)
  68                 return ret;
  69         if (tb[TCA_MIRRED_PARMS] == NULL)
  70                 return -EINVAL;
  71         parm = nla_data(tb[TCA_MIRRED_PARMS]);
  72         switch (parm->eaction) {
  73         case TCA_EGRESS_MIRROR:
  74         case TCA_EGRESS_REDIR:
  75                 break;
  76         default:
  77                 return -EINVAL;
  78         }
  79         if (parm->ifindex) {
  80                 dev = __dev_get_by_index(net, parm->ifindex);
  81                 if (dev == NULL)
  82                         return -ENODEV;
  83                 switch (dev->type) {
  84                 case ARPHRD_TUNNEL:
  85                 case ARPHRD_TUNNEL6:
  86                 case ARPHRD_SIT:
  87                 case ARPHRD_IPGRE:
  88                 case ARPHRD_VOID:
  89                 case ARPHRD_NONE:
  90                         ok_push = 0;
  91                         break;
  92                 default:
  93                         ok_push = 1;
  94                         break;
  95                 }
  96         } else {
  97                 dev = NULL;
  98         }
  99
 100         if (!tcf_hash_check(parm->index, a, bind)) {
 101                 if (dev == NULL)
 102                         return -EINVAL;
 103                 ret = tcf_hash_create(parm->index, est, a, sizeof(*m),
 104                                       bind, true);
 105                 if (ret)
 106                         return ret;
 107                 ret = ACT_P_CREATED;
 108         } else {
 109                 if (bind)
 110                         return 0;
 111
 112                 tcf_hash_release(a, bind);
 113                 if (!ovr)
 114                         return -EEXIST;
 115         }
 116         m = to_mirred(a);
 117
 118         ASSERT_RTNL();
 119         m->tcf_action = parm->action;
 120         m->tcfm_eaction = parm->eaction;
 121         if (dev != NULL) {
 122                 m->tcfm_ifindex = parm->ifindex;
 123                 if (ret != ACT_P_CREATED)
 124                         dev_put(rcu_dereference_protected(m->tcfm_dev, 1));
 125                 dev_hold(dev);
 126                 rcu_assign_pointer(m->tcfm_dev, dev);
 127                 m->tcfm_ok_push = ok_push;
 128         }
 129
 130         if (ret == ACT_P_CREATED) {
 131                 spin_lock_bh(&mirred_list_lock);
 132                 list_add(&m->tcfm_list, &mirred_list);
 133                 spin_unlock_bh(&mirred_list_lock);
 134                 tcf_hash_insert(a);
 135         }
 136
 137         return ret;
 138 }
 139
 140 static int tcf_mirred(struct sk_buff *skb, const struct tc_action *a,
 141                       struct tcf_result *res)
 142 {
 143         struct tcf_mirred *m = a->priv;
 144         struct net_device *dev;
 145         struct sk_buff *skb2;
 146         int retval, err;
 147         u32 at;
 148
 149         tcf_lastuse_update(&m->tcf_tm);
 150
 151         bstats_cpu_update(this_cpu_ptr(m->common.cpu_bstats), skb);
 152
 153         rcu_read_lock();
 154         retval = READ_ONCE(m->tcf_action);
 155         dev = rcu_dereference(m->tcfm_dev);
 156         if (unlikely(!dev)) {
 157                 pr_notice_once("tc mirred: target device is gone\n");
 158                 goto out;
 159         }
 160
 161         if (unlikely(!(dev->flags & IFF_UP))) {
 162                 net_notice_ratelimited("tc mirred to Houston: device %s is down\n",
 163                                        dev->name);
 164                 goto out;
 165         }
 166
 167         at = G_TC_AT(skb->tc_verd);
 168         skb2 = skb_clone(skb, GFP_ATOMIC);
 169         if (!skb2)
 170                 goto out;
 171
 172         if (!(at & AT_EGRESS)) {
 173                 if (m->tcfm_ok_push)
 174                         skb_push_rcsum(skb2, skb->mac_len);
 175         }
 176
 177         /* mirror is always swallowed */
 178         if (m->tcfm_eaction != TCA_EGRESS_MIRROR)
 179                 skb2->tc_verd = SET_TC_FROM(skb2->tc_verd, at);
 180
 181         skb2->skb_iif = skb->dev->ifindex;
 182         skb2->dev = dev;
 183         skb_sender_cpu_clear(skb2);
 184         err = dev_queue_xmit(skb2);
 185
 186         if (err) {
 187 out:
 188                 qstats_overlimit_inc(this_cpu_ptr(m->common.cpu_qstats));
 189                 if (m->tcfm_eaction != TCA_EGRESS_MIRROR)
 190                         retval = TC_ACT_SHOT;
 191         }
 192         rcu_read_unlock();
 193
 194         return retval;
 195 }
 196
 197 static int tcf_mirred_dump(struct sk_buff *skb, struct tc_action *a, int bind, int ref)
 198 {
 199         unsigned char *b = skb_tail_pointer(skb);
 200         struct tcf_mirred *m = a->priv;
 201         struct tc_mirred opt = {
 202                 .index   = m->tcf_index,
 203                 .action  = m->tcf_action,
 204                 .refcnt  = m->tcf_refcnt - ref,
 205                 .bindcnt = m->tcf_bindcnt - bind,
 206                 .eaction = m->tcfm_eaction,
 207                 .ifindex = m->tcfm_ifindex,
 208         };
 209         struct tcf_t t;
 210
 211         if (nla_put(skb, TCA_MIRRED_PARMS, sizeof(opt), &opt))
 212                 goto nla_put_failure;
 213         t.install = jiffies_to_clock_t(jiffies - m->tcf_tm.install);
 214         t.lastuse = jiffies_to_clock_t(jiffies - m->tcf_tm.lastuse);
 215         t.expires = jiffies_to_clock_t(m->tcf_tm.expires);
 216         if (nla_put(skb, TCA_MIRRED_TM, sizeof(t), &t))
 217                 goto nla_put_failure;
 218         return skb->len;
 219
 220 nla_put_failure:
 221         nlmsg_trim(skb, b);
 222         return -1;
 223 }
 224
 225 static int mirred_device_event(struct notifier_block *unused,
 226                                unsigned long event, void *ptr)
 227 {
 228         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 229         struct tcf_mirred *m;
 230
 231         ASSERT_RTNL();
 232         if (event == NETDEV_UNREGISTER) {
 233                 spin_lock_bh(&mirred_list_lock);
 234                 list_for_each_entry(m, &mirred_list, tcfm_list) {
 235                         if (rcu_access_pointer(m->tcfm_dev) == dev) {
 236                                 dev_put(dev);
 237                                 /* Note : no rcu grace period necessary, as
 238                                  * net_device are already rcu protected.
 239                                  */
 240                                 RCU_INIT_POINTER(m->tcfm_dev, NULL);
 241                         }
 242                 }
 243                 spin_unlock_bh(&mirred_list_lock);
 244         }
 245
 246         return NOTIFY_DONE;
 247 }
 248
 249 static struct notifier_block mirred_device_notifier = {
 250         .notifier_call = mirred_device_event,
 251 };
 252
 253 static struct tc_action_ops act_mirred_ops = {
 254         .kind           =       "mirred",
 255         .type           =       TCA_ACT_MIRRED,
 256         .owner          =       THIS_MODULE,
 257         .act            =       tcf_mirred,
 258         .dump           =       tcf_mirred_dump,
 259         .cleanup        =       tcf_mirred_release,
 260         .init           =       tcf_mirred_init,
 261 };
 262
 263 MODULE_AUTHOR("Jamal Hadi Salim(2002)");
 264 MODULE_DESCRIPTION("Device Mirror/redirect actions");
 265 MODULE_LICENSE("GPL");
 266
 267 static int __init mirred_init_module(void)
 268 {
 269         int err = register_netdevice_notifier(&mirred_device_notifier);
 270         if (err)
 271                 return err;
 272
 273         pr_info("Mirror/redirect action on\n");
 274         return tcf_register_action(&act_mirred_ops, MIRRED_TAB_MASK);
 275 }
 276
 277 static void __exit mirred_cleanup_module(void)
 278 {
 279         tcf_unregister_action(&act_mirred_ops);
 280         unregister_netdevice_notifier(&mirred_device_notifier);
 281 }
 282
 283 module_init(mirred_init_module);
 284 module_exit(mirred_cleanup_module);