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         case TCA_INGRESS_REDIR:
  76                 break;
  77         default:
  78                 return -EINVAL;
  79         }
  80         if (parm->ifindex) {
  81                 dev = __dev_get_by_index(net, parm->ifindex);
  82                 if (dev == NULL)
  83                         return -ENODEV;
  84                 switch (dev->type) {
  85                 case ARPHRD_TUNNEL:
  86                 case ARPHRD_TUNNEL6:
  87                 case ARPHRD_SIT:
  88                 case ARPHRD_IPGRE:
  89                 case ARPHRD_VOID:
  90                 case ARPHRD_NONE:
  91                         ok_push = 0;
  92                         break;
  93                 default:
  94                         ok_push = 1;
  95                         break;
  96                 }
  97         } else {
  98                 dev = NULL;
  99         }
 100
 101         if (!tcf_hash_check(parm->index, a, bind)) {
 102                 if (dev == NULL)
 103                         return -EINVAL;
 104                 ret = tcf_hash_create(parm->index, est, a, sizeof(*m),
 105                                       bind, true);
 106                 if (ret)
 107                         return ret;
 108                 ret = ACT_P_CREATED;
 109         } else {
 110                 if (bind)
 111                         return 0;
 112
 113                 tcf_hash_release(a, bind);
 114                 if (!ovr)
 115                         return -EEXIST;
 116         }
 117         m = to_mirred(a);
 118
 119         ASSERT_RTNL();
 120         m->tcf_action = parm->action;
 121         m->tcfm_eaction = parm->eaction;
 122         if (dev != NULL) {
 123                 m->tcfm_ifindex = parm->ifindex;
 124                 if (ret != ACT_P_CREATED)
 125                         dev_put(rcu_dereference_protected(m->tcfm_dev, 1));
 126                 dev_hold(dev);
 127                 rcu_assign_pointer(m->tcfm_dev, dev);
 128                 m->tcfm_ok_push = ok_push;
 129         }
 130
 131         if (ret == ACT_P_CREATED) {
 132                 spin_lock_bh(&mirred_list_lock);
 133                 list_add(&m->tcfm_list, &mirred_list);
 134                 spin_unlock_bh(&mirred_list_lock);
 135                 tcf_hash_insert(a);
 136         }
 137
 138         return ret;
 139 }
 140
 141 static int tcf_mirred(struct sk_buff *skb, const struct tc_action *a,
 142                       struct tcf_result *res)
 143 {
 144         struct tcf_mirred *m = a->priv;
 145         struct net_device *dev;
 146         struct sk_buff *skb2;
 147         int retval, err;
 148         u32 at;
 149
 150         tcf_lastuse_update(&m->tcf_tm);
 151
 152         bstats_cpu_update(this_cpu_ptr(m->common.cpu_bstats), skb);
 153
 154         rcu_read_lock();
 155         retval = READ_ONCE(m->tcf_action);
 156         dev = rcu_dereference(m->tcfm_dev);
 157         if (unlikely(!dev)) {
 158                 pr_notice_once("tc mirred: target device is gone\n");
 159                 goto out;
 160         }
 161
 162         if (unlikely(!(dev->flags & IFF_UP))) {
 163                 net_notice_ratelimited("tc mirred to Houston: device %s is down\n",
 164                                        dev->name);
 165                 goto out;
 166         }
 167
 168         skb2 = skb_clone(skb, GFP_ATOMIC);
 169         if (!skb2)
 170                 goto out;
 171
 172         if (m->tcfm_eaction == TCA_INGRESS_REDIR) {
 173                 /* Let's _hope_ the devices are of similar type.
 174                  * This is rather dangerous; with changed skb_iif, we
 175                  * will not know the real input device, but perhaps
 176                  * that's the whole point of doing the ingress
 177                  * redirect/mirror in the first place?  (Note: This
 178                  * can lead to bad things if two devices ingress
 179                  * redirect at each other. Don't do that.)*/
 180                 skb2->dev = dev;
 181                 skb2->skb_iif = skb2->dev->ifindex;
 182                 skb2->pkt_type = PACKET_HOST;
 183                 netif_rx(skb2);
 184         } else {
 185                 at = G_TC_AT(skb->tc_verd);
 186                 if (!(at & AT_EGRESS)) {
 187                         if (m->tcfm_ok_push)
 188                                 skb_push(skb2, skb->mac_len);
 189                 }
 190
 191                 /* mirror is always swallowed */
 192                 if (m->tcfm_eaction != TCA_EGRESS_MIRROR)
 193                         skb2->tc_verd = SET_TC_FROM(skb2->tc_verd, at);
 194
 195                 skb2->skb_iif = skb->dev->ifindex;
 196                 skb2->dev = dev;
 197                 skb_sender_cpu_clear(skb2);
 198                 err = dev_queue_xmit(skb2);
 199         }
 200
 201         if (err) {
 202 out:
 203                 qstats_overlimit_inc(this_cpu_ptr(m->common.cpu_qstats));
 204                 if (m->tcfm_eaction != TCA_EGRESS_MIRROR)
 205                         retval = TC_ACT_SHOT;
 206         }
 207         rcu_read_unlock();
 208
 209         return retval;
 210 }
 211
 212 static int tcf_mirred_dump(struct sk_buff *skb, struct tc_action *a, int bind, int ref)
 213 {
 214         unsigned char *b = skb_tail_pointer(skb);
 215         struct tcf_mirred *m = a->priv;
 216         struct tc_mirred opt = {
 217                 .index   = m->tcf_index,
 218                 .action  = m->tcf_action,
 219                 .refcnt  = m->tcf_refcnt - ref,
 220                 .bindcnt = m->tcf_bindcnt - bind,
 221                 .eaction = m->tcfm_eaction,
 222                 .ifindex = m->tcfm_ifindex,
 223         };
 224         struct tcf_t t;
 225
 226         if (nla_put(skb, TCA_MIRRED_PARMS, sizeof(opt), &opt))
 227                 goto nla_put_failure;
 228         t.install = jiffies_to_clock_t(jiffies - m->tcf_tm.install);
 229         t.lastuse = jiffies_to_clock_t(jiffies - m->tcf_tm.lastuse);
 230         t.expires = jiffies_to_clock_t(m->tcf_tm.expires);
 231         if (nla_put(skb, TCA_MIRRED_TM, sizeof(t), &t))
 232                 goto nla_put_failure;
 233         return skb->len;
 234
 235 nla_put_failure:
 236         nlmsg_trim(skb, b);
 237         return -1;
 238 }
 239
 240 static int mirred_device_event(struct notifier_block *unused,
 241                                unsigned long event, void *ptr)
 242 {
 243         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 244         struct tcf_mirred *m;
 245
 246         ASSERT_RTNL();
 247         if (event == NETDEV_UNREGISTER) {
 248                 spin_lock_bh(&mirred_list_lock);
 249                 list_for_each_entry(m, &mirred_list, tcfm_list) {
 250                         if (rcu_access_pointer(m->tcfm_dev) == dev) {
 251                                 dev_put(dev);
 252                                 /* Note : no rcu grace period necessary, as
 253                                  * net_device are already rcu protected.
 254                                  */
 255                                 RCU_INIT_POINTER(m->tcfm_dev, NULL);
 256                         }
 257                 }
 258                 spin_unlock_bh(&mirred_list_lock);
 259         }
 260
 261         return NOTIFY_DONE;
 262 }
 263
 264 static struct notifier_block mirred_device_notifier = {
 265         .notifier_call = mirred_device_event,
 266 };
 267
 268 static struct tc_action_ops act_mirred_ops = {
 269         .kind           =       "mirred",
 270         .type           =       TCA_ACT_MIRRED,
 271         .owner          =       THIS_MODULE,
 272         .act            =       tcf_mirred,
 273         .dump           =       tcf_mirred_dump,
 274         .cleanup        =       tcf_mirred_release,
 275         .init           =       tcf_mirred_init,
 276 };
 277
 278 MODULE_AUTHOR("Jamal Hadi Salim(2002)");
 279 MODULE_DESCRIPTION("Device Mirror/redirect actions");
 280 MODULE_LICENSE("GPL");
 281
 282 static int __init mirred_init_module(void)
 283 {
 284         int err = register_netdevice_notifier(&mirred_device_notifier);
 285         if (err)
 286                 return err;
 287
 288         pr_info("Mirror/redirect action on\n");
 289         return tcf_register_action(&act_mirred_ops, MIRRED_TAB_MASK);
 290 }
 291
 292 static void __exit mirred_cleanup_module(void)
 293 {
 294         tcf_unregister_action(&act_mirred_ops);
 295         unregister_netdevice_notifier(&mirred_device_notifier);
 296 }
 297
 298 module_init(mirred_init_module);
 299 module_exit(mirred_cleanup_module);