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 static DEFINE_SPINLOCK(mirred_list_lock); 33 34 static bool tcf_mirred_is_act_redirect(int action) 35 { 36 return action == TCA_EGRESS_REDIR || action == TCA_INGRESS_REDIR; 37 } 38 39 static bool tcf_mirred_act_wants_ingress(int action) 40 { 41 switch (action) { 42 case TCA_EGRESS_REDIR: 43 case TCA_EGRESS_MIRROR: 44 return false; 45 case TCA_INGRESS_REDIR: 46 case TCA_INGRESS_MIRROR: 47 return true; 48 default: 49 BUG(); 50 } 51 } 52 53 static void tcf_mirred_release(struct tc_action *a, int bind) 54 { 55 struct tcf_mirred *m = to_mirred(a); 56 struct net_device *dev; 57 58 /* We could be called either in a RCU callback or with RTNL lock held. */ 59 spin_lock_bh(&mirred_list_lock); 60 list_del(&m->tcfm_list); 61 dev = rcu_dereference_protected(m->tcfm_dev, 1); 62 if (dev) 63 dev_put(dev); 64 spin_unlock_bh(&mirred_list_lock); 65 } 66 67 static const struct nla_policy mirred_policy[TCA_MIRRED_MAX + 1] = { 68 [TCA_MIRRED_PARMS] = { .len = sizeof(struct tc_mirred) }, 69 }; 70 71 static unsigned int mirred_net_id; 72 static struct tc_action_ops act_mirred_ops; 73 74 static int tcf_mirred_init(struct net *net, struct nlattr *nla, 75 struct nlattr *est, struct tc_action **a, int ovr, 76 int bind) 77 { 78 struct tc_action_net *tn = net_generic(net, mirred_net_id); 79 struct nlattr *tb[TCA_MIRRED_MAX + 1]; 80 bool mac_header_xmit = false; 81 struct tc_mirred *parm; 82 struct tcf_mirred *m; 83 struct net_device *dev; 84 bool exists = false; 85 int ret; 86 87 if (nla == NULL) 88 return -EINVAL; 89 ret = nla_parse_nested(tb, TCA_MIRRED_MAX, nla, mirred_policy, NULL); 90 if (ret < 0) 91 return ret; 92 if (tb[TCA_MIRRED_PARMS] == NULL) 93 return -EINVAL; 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 return -EINVAL; 110 } 111 if (parm->ifindex) { 112 dev = __dev_get_by_index(net, parm->ifindex); 113 if (dev == NULL) { 114 if (exists) 115 tcf_idr_release(*a, bind); 116 return -ENODEV; 117 } 118 mac_header_xmit = dev_is_mac_header_xmit(dev); 119 } else { 120 dev = NULL; 121 } 122 123 if (!exists) { 124 if (dev == NULL) 125 return -EINVAL; 126 ret = tcf_idr_create(tn, parm->index, est, a, 127 &act_mirred_ops, bind, true); 128 if (ret) 129 return ret; 130 ret = ACT_P_CREATED; 131 } else { 132 tcf_idr_release(*a, bind); 133 if (!ovr) 134 return -EEXIST; 135 } 136 m = to_mirred(*a); 137 138 ASSERT_RTNL(); 139 m->tcf_action = parm->action; 140 m->tcfm_eaction = parm->eaction; 141 if (dev != NULL) { 142 m->tcfm_ifindex = parm->ifindex; 143 if (ret != ACT_P_CREATED) 144 dev_put(rcu_dereference_protected(m->tcfm_dev, 1)); 145 dev_hold(dev); 146 rcu_assign_pointer(m->tcfm_dev, dev); 147 m->tcfm_mac_header_xmit = mac_header_xmit; 148 } 149 150 if (ret == ACT_P_CREATED) { 151 spin_lock_bh(&mirred_list_lock); 152 list_add(&m->tcfm_list, &mirred_list); 153 spin_unlock_bh(&mirred_list_lock); 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 = 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 tc_mirred opt = { 250 .index = m->tcf_index, 251 .action = m->tcf_action, 252 .refcnt = m->tcf_refcnt - ref, 253 .bindcnt = m->tcf_bindcnt - bind, 254 .eaction = m->tcfm_eaction, 255 .ifindex = m->tcfm_ifindex, 256 }; 257 struct tcf_t t; 258 259 if (nla_put(skb, TCA_MIRRED_PARMS, sizeof(opt), &opt)) 260 goto nla_put_failure; 261 262 tcf_tm_dump(&t, &m->tcf_tm); 263 if (nla_put_64bit(skb, TCA_MIRRED_TM, sizeof(t), &t, TCA_MIRRED_PAD)) 264 goto nla_put_failure; 265 return skb->len; 266 267 nla_put_failure: 268 nlmsg_trim(skb, b); 269 return -1; 270 } 271 272 static int tcf_mirred_walker(struct net *net, struct sk_buff *skb, 273 struct netlink_callback *cb, int type, 274 const struct tc_action_ops *ops) 275 { 276 struct tc_action_net *tn = net_generic(net, mirred_net_id); 277 278 return tcf_generic_walker(tn, skb, cb, type, ops); 279 } 280 281 static int tcf_mirred_search(struct net *net, struct tc_action **a, u32 index) 282 { 283 struct tc_action_net *tn = net_generic(net, mirred_net_id); 284 285 return tcf_idr_search(tn, a, index); 286 } 287 288 static int mirred_device_event(struct notifier_block *unused, 289 unsigned long event, void *ptr) 290 { 291 struct net_device *dev = netdev_notifier_info_to_dev(ptr); 292 struct tcf_mirred *m; 293 294 ASSERT_RTNL(); 295 if (event == NETDEV_UNREGISTER) { 296 spin_lock_bh(&mirred_list_lock); 297 list_for_each_entry(m, &mirred_list, tcfm_list) { 298 if (rcu_access_pointer(m->tcfm_dev) == dev) { 299 dev_put(dev); 300 /* Note : no rcu grace period necessary, as 301 * net_device are already rcu protected. 302 */ 303 RCU_INIT_POINTER(m->tcfm_dev, NULL); 304 } 305 } 306 spin_unlock_bh(&mirred_list_lock); 307 } 308 309 return NOTIFY_DONE; 310 } 311 312 static struct notifier_block mirred_device_notifier = { 313 .notifier_call = mirred_device_event, 314 }; 315 316 static int tcf_mirred_device(const struct tc_action *a, struct net *net, 317 struct net_device **mirred_dev) 318 { 319 int ifindex = tcf_mirred_ifindex(a); 320 321 *mirred_dev = __dev_get_by_index(net, ifindex); 322 if (!*mirred_dev) 323 return -EINVAL; 324 return 0; 325 } 326 327 static struct tc_action_ops act_mirred_ops = { 328 .kind = "mirred", 329 .type = TCA_ACT_MIRRED, 330 .owner = THIS_MODULE, 331 .act = tcf_mirred, 332 .stats_update = tcf_stats_update, 333 .dump = tcf_mirred_dump, 334 .cleanup = tcf_mirred_release, 335 .init = tcf_mirred_init, 336 .walk = tcf_mirred_walker, 337 .lookup = tcf_mirred_search, 338 .size = sizeof(struct tcf_mirred), 339 .get_dev = tcf_mirred_device, 340 }; 341 342 static __net_init int mirred_init_net(struct net *net) 343 { 344 struct tc_action_net *tn = net_generic(net, mirred_net_id); 345 346 return tc_action_net_init(tn, &act_mirred_ops); 347 } 348 349 static void __net_exit mirred_exit_net(struct net *net) 350 { 351 struct tc_action_net *tn = net_generic(net, mirred_net_id); 352 353 tc_action_net_exit(tn); 354 } 355 356 static struct pernet_operations mirred_net_ops = { 357 .init = mirred_init_net, 358 .exit = mirred_exit_net, 359 .id = &mirred_net_id, 360 .size = sizeof(struct tc_action_net), 361 }; 362 363 MODULE_AUTHOR("Jamal Hadi Salim(2002)"); 364 MODULE_DESCRIPTION("Device Mirror/redirect actions"); 365 MODULE_LICENSE("GPL"); 366 367 static int __init mirred_init_module(void) 368 { 369 int err = register_netdevice_notifier(&mirred_device_notifier); 370 if (err) 371 return err; 372 373 pr_info("Mirror/redirect action on\n"); 374 return tcf_register_action(&act_mirred_ops, &mirred_net_ops); 375 } 376 377 static void __exit mirred_cleanup_module(void) 378 { 379 tcf_unregister_action(&act_mirred_ops, &mirred_net_ops); 380 unregister_netdevice_notifier(&mirred_device_notifier); 381 } 382 383 module_init(mirred_init_module); 384 module_exit(mirred_cleanup_module); 385