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 #define MIRRED_TAB_MASK 7 32 static LIST_HEAD(mirred_list); 33 static DEFINE_SPINLOCK(mirred_list_lock); 34 35 static bool tcf_mirred_is_act_redirect(int action) 36 { 37 return action == TCA_EGRESS_REDIR || action == TCA_INGRESS_REDIR; 38 } 39 40 static bool tcf_mirred_act_wants_ingress(int action) 41 { 42 switch (action) { 43 case TCA_EGRESS_REDIR: 44 case TCA_EGRESS_MIRROR: 45 return false; 46 case TCA_INGRESS_REDIR: 47 case TCA_INGRESS_MIRROR: 48 return true; 49 default: 50 BUG(); 51 } 52 } 53 54 static void tcf_mirred_release(struct tc_action *a, int bind) 55 { 56 struct tcf_mirred *m = to_mirred(a); 57 struct net_device *dev; 58 59 /* We could be called either in a RCU callback or with RTNL lock held. */ 60 spin_lock_bh(&mirred_list_lock); 61 list_del(&m->tcfm_list); 62 dev = rcu_dereference_protected(m->tcfm_dev, 1); 63 if (dev) 64 dev_put(dev); 65 spin_unlock_bh(&mirred_list_lock); 66 } 67 68 static const struct nla_policy mirred_policy[TCA_MIRRED_MAX + 1] = { 69 [TCA_MIRRED_PARMS] = { .len = sizeof(struct tc_mirred) }, 70 }; 71 72 static unsigned int mirred_net_id; 73 static struct tc_action_ops act_mirred_ops; 74 75 static int tcf_mirred_init(struct net *net, struct nlattr *nla, 76 struct nlattr *est, struct tc_action **a, int ovr, 77 int bind) 78 { 79 struct tc_action_net *tn = net_generic(net, mirred_net_id); 80 struct nlattr *tb[TCA_MIRRED_MAX + 1]; 81 bool mac_header_xmit = false; 82 struct tc_mirred *parm; 83 struct tcf_mirred *m; 84 struct net_device *dev; 85 bool exists = false; 86 int ret; 87 88 if (nla == NULL) 89 return -EINVAL; 90 ret = nla_parse_nested(tb, TCA_MIRRED_MAX, nla, mirred_policy, NULL); 91 if (ret < 0) 92 return ret; 93 if (tb[TCA_MIRRED_PARMS] == NULL) 94 return -EINVAL; 95 parm = nla_data(tb[TCA_MIRRED_PARMS]); 96 97 exists = tcf_hash_check(tn, parm->index, a, bind); 98 if (exists && bind) 99 return 0; 100 101 switch (parm->eaction) { 102 case TCA_EGRESS_MIRROR: 103 case TCA_EGRESS_REDIR: 104 case TCA_INGRESS_REDIR: 105 case TCA_INGRESS_MIRROR: 106 break; 107 default: 108 if (exists) 109 tcf_hash_release(*a, bind); 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_hash_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 == NULL) 126 return -EINVAL; 127 ret = tcf_hash_create(tn, parm->index, est, a, 128 &act_mirred_ops, bind, true); 129 if (ret) 130 return ret; 131 ret = ACT_P_CREATED; 132 } else { 133 tcf_hash_release(*a, bind); 134 if (!ovr) 135 return -EEXIST; 136 } 137 m = to_mirred(*a); 138 139 ASSERT_RTNL(); 140 m->tcf_action = parm->action; 141 m->tcfm_eaction = parm->eaction; 142 if (dev != NULL) { 143 m->tcfm_ifindex = parm->ifindex; 144 if (ret != ACT_P_CREATED) 145 dev_put(rcu_dereference_protected(m->tcfm_dev, 1)); 146 dev_hold(dev); 147 rcu_assign_pointer(m->tcfm_dev, dev); 148 m->tcfm_mac_header_xmit = mac_header_xmit; 149 } 150 151 if (ret == ACT_P_CREATED) { 152 spin_lock_bh(&mirred_list_lock); 153 list_add(&m->tcfm_list, &mirred_list); 154 spin_unlock_bh(&mirred_list_lock); 155 tcf_hash_insert(tn, *a); 156 } 157 158 return ret; 159 } 160 161 static int tcf_mirred(struct sk_buff *skb, const struct tc_action *a, 162 struct tcf_result *res) 163 { 164 struct tcf_mirred *m = to_mirred(a); 165 bool m_mac_header_xmit; 166 struct net_device *dev; 167 struct sk_buff *skb2; 168 int retval, err = 0; 169 int m_eaction; 170 int mac_len; 171 172 tcf_lastuse_update(&m->tcf_tm); 173 bstats_cpu_update(this_cpu_ptr(m->common.cpu_bstats), skb); 174 175 rcu_read_lock(); 176 m_mac_header_xmit = READ_ONCE(m->tcfm_mac_header_xmit); 177 m_eaction = READ_ONCE(m->tcfm_eaction); 178 retval = READ_ONCE(m->tcf_action); 179 dev = rcu_dereference(m->tcfm_dev); 180 if (unlikely(!dev)) { 181 pr_notice_once("tc mirred: target device is gone\n"); 182 goto out; 183 } 184 185 if (unlikely(!(dev->flags & IFF_UP))) { 186 net_notice_ratelimited("tc mirred to Houston: device %s is down\n", 187 dev->name); 188 goto out; 189 } 190 191 skb2 = skb_clone(skb, GFP_ATOMIC); 192 if (!skb2) 193 goto out; 194 195 /* If action's target direction differs than filter's direction, 196 * and devices expect a mac header on xmit, then mac push/pull is 197 * needed. 198 */ 199 if (skb_at_tc_ingress(skb) != tcf_mirred_act_wants_ingress(m_eaction) && 200 m_mac_header_xmit) { 201 if (!skb_at_tc_ingress(skb)) { 202 /* caught at egress, act ingress: pull mac */ 203 mac_len = skb_network_header(skb) - skb_mac_header(skb); 204 skb_pull_rcsum(skb2, mac_len); 205 } else { 206 /* caught at ingress, act egress: push mac */ 207 skb_push_rcsum(skb2, skb->mac_len); 208 } 209 } 210 211 /* mirror is always swallowed */ 212 if (tcf_mirred_is_act_redirect(m_eaction)) { 213 skb2->tc_redirected = 1; 214 skb2->tc_from_ingress = skb2->tc_at_ingress; 215 } 216 217 skb2->skb_iif = skb->dev->ifindex; 218 skb2->dev = dev; 219 if (!tcf_mirred_act_wants_ingress(m_eaction)) 220 err = dev_queue_xmit(skb2); 221 else 222 err = netif_receive_skb(skb2); 223 224 if (err) { 225 out: 226 qstats_overlimit_inc(this_cpu_ptr(m->common.cpu_qstats)); 227 if (tcf_mirred_is_act_redirect(m_eaction)) 228 retval = TC_ACT_SHOT; 229 } 230 rcu_read_unlock(); 231 232 return retval; 233 } 234 235 static void tcf_stats_update(struct tc_action *a, u64 bytes, u32 packets, 236 u64 lastuse) 237 { 238 struct tcf_mirred *m = to_mirred(a); 239 struct tcf_t *tm = &m->tcf_tm; 240 241 _bstats_cpu_update(this_cpu_ptr(a->cpu_bstats), bytes, packets); 242 tm->lastuse = lastuse; 243 } 244 245 static int tcf_mirred_dump(struct sk_buff *skb, struct tc_action *a, int bind, 246 int ref) 247 { 248 unsigned char *b = skb_tail_pointer(skb); 249 struct tcf_mirred *m = to_mirred(a); 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 = m->tcfm_ifindex, 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 { 277 struct tc_action_net *tn = net_generic(net, mirred_net_id); 278 279 return tcf_generic_walker(tn, skb, cb, type, ops); 280 } 281 282 static int tcf_mirred_search(struct net *net, struct tc_action **a, u32 index) 283 { 284 struct tc_action_net *tn = net_generic(net, mirred_net_id); 285 286 return tcf_hash_search(tn, a, index); 287 } 288 289 static int mirred_device_event(struct notifier_block *unused, 290 unsigned long event, void *ptr) 291 { 292 struct net_device *dev = netdev_notifier_info_to_dev(ptr); 293 struct tcf_mirred *m; 294 295 ASSERT_RTNL(); 296 if (event == NETDEV_UNREGISTER) { 297 spin_lock_bh(&mirred_list_lock); 298 list_for_each_entry(m, &mirred_list, tcfm_list) { 299 if (rcu_access_pointer(m->tcfm_dev) == dev) { 300 dev_put(dev); 301 /* Note : no rcu grace period necessary, as 302 * net_device are already rcu protected. 303 */ 304 RCU_INIT_POINTER(m->tcfm_dev, NULL); 305 } 306 } 307 spin_unlock_bh(&mirred_list_lock); 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 int tcf_mirred_device(const struct tc_action *a, struct net *net, 318 struct net_device **mirred_dev) 319 { 320 int ifindex = tcf_mirred_ifindex(a); 321 322 *mirred_dev = __dev_get_by_index(net, ifindex); 323 if (!*mirred_dev) 324 return -EINVAL; 325 return 0; 326 } 327 328 static struct tc_action_ops act_mirred_ops = { 329 .kind = "mirred", 330 .type = TCA_ACT_MIRRED, 331 .owner = THIS_MODULE, 332 .act = tcf_mirred, 333 .stats_update = tcf_stats_update, 334 .dump = tcf_mirred_dump, 335 .cleanup = tcf_mirred_release, 336 .init = tcf_mirred_init, 337 .walk = tcf_mirred_walker, 338 .lookup = tcf_mirred_search, 339 .size = sizeof(struct tcf_mirred), 340 .get_dev = tcf_mirred_device, 341 }; 342 343 static __net_init int mirred_init_net(struct net *net) 344 { 345 struct tc_action_net *tn = net_generic(net, mirred_net_id); 346 347 return tc_action_net_init(tn, &act_mirred_ops, MIRRED_TAB_MASK); 348 } 349 350 static void __net_exit mirred_exit_net(struct net *net) 351 { 352 struct tc_action_net *tn = net_generic(net, mirred_net_id); 353 354 tc_action_net_exit(tn); 355 } 356 357 static struct pernet_operations mirred_net_ops = { 358 .init = mirred_init_net, 359 .exit = mirred_exit_net, 360 .id = &mirred_net_id, 361 .size = sizeof(struct tc_action_net), 362 }; 363 364 MODULE_AUTHOR("Jamal Hadi Salim(2002)"); 365 MODULE_DESCRIPTION("Device Mirror/redirect actions"); 366 MODULE_LICENSE("GPL"); 367 368 static int __init mirred_init_module(void) 369 { 370 int err = register_netdevice_notifier(&mirred_device_notifier); 371 if (err) 372 return err; 373 374 pr_info("Mirror/redirect action on\n"); 375 return tcf_register_action(&act_mirred_ops, &mirred_net_ops); 376 } 377 378 static void __exit mirred_cleanup_module(void) 379 { 380 tcf_unregister_action(&act_mirred_ops, &mirred_net_ops); 381 unregister_netdevice_notifier(&mirred_device_notifier); 382 } 383 384 module_init(mirred_init_module); 385 module_exit(mirred_cleanup_module); 386