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 33 static bool tcf_mirred_is_act_redirect(int action) 34 { 35 return action == TCA_EGRESS_REDIR || action == TCA_INGRESS_REDIR; 36 } 37 38 static bool tcf_mirred_act_wants_ingress(int action) 39 { 40 switch (action) { 41 case TCA_EGRESS_REDIR: 42 case TCA_EGRESS_MIRROR: 43 return false; 44 case TCA_INGRESS_REDIR: 45 case TCA_INGRESS_MIRROR: 46 return true; 47 default: 48 BUG(); 49 } 50 } 51 52 static void tcf_mirred_release(struct tc_action *a) 53 { 54 struct tcf_mirred *m = to_mirred(a); 55 struct net_device *dev; 56 57 list_del(&m->tcfm_list); 58 dev = rtnl_dereference(m->tcfm_dev); 59 if (dev) 60 dev_put(dev); 61 } 62 63 static const struct nla_policy mirred_policy[TCA_MIRRED_MAX + 1] = { 64 [TCA_MIRRED_PARMS] = { .len = sizeof(struct tc_mirred) }, 65 }; 66 67 static unsigned int mirred_net_id; 68 static struct tc_action_ops act_mirred_ops; 69 70 static int tcf_mirred_init(struct net *net, struct nlattr *nla, 71 struct nlattr *est, struct tc_action **a, 72 int ovr, int bind, bool rtnl_held, 73 struct netlink_ext_ack *extack) 74 { 75 struct tc_action_net *tn = net_generic(net, mirred_net_id); 76 struct nlattr *tb[TCA_MIRRED_MAX + 1]; 77 bool mac_header_xmit = false; 78 struct tc_mirred *parm; 79 struct tcf_mirred *m; 80 struct net_device *dev; 81 bool exists = false; 82 int ret, err; 83 84 if (!nla) { 85 NL_SET_ERR_MSG_MOD(extack, "Mirred requires attributes to be passed"); 86 return -EINVAL; 87 } 88 ret = nla_parse_nested(tb, TCA_MIRRED_MAX, nla, mirred_policy, extack); 89 if (ret < 0) 90 return ret; 91 if (!tb[TCA_MIRRED_PARMS]) { 92 NL_SET_ERR_MSG_MOD(extack, "Missing required mirred parameters"); 93 return -EINVAL; 94 } 95 parm = nla_data(tb[TCA_MIRRED_PARMS]); 96 97 err = tcf_idr_check_alloc(tn, &parm->index, a, bind); 98 if (err < 0) 99 return err; 100 exists = err; 101 if (exists && bind) 102 return 0; 103 104 switch (parm->eaction) { 105 case TCA_EGRESS_MIRROR: 106 case TCA_EGRESS_REDIR: 107 case TCA_INGRESS_REDIR: 108 case TCA_INGRESS_MIRROR: 109 break; 110 default: 111 if (exists) 112 tcf_idr_release(*a, bind); 113 else 114 tcf_idr_cleanup(tn, parm->index); 115 NL_SET_ERR_MSG_MOD(extack, "Unknown mirred option"); 116 return -EINVAL; 117 } 118 if (parm->ifindex) { 119 dev = __dev_get_by_index(net, parm->ifindex); 120 if (dev == NULL) { 121 if (exists) 122 tcf_idr_release(*a, bind); 123 else 124 tcf_idr_cleanup(tn, parm->index); 125 return -ENODEV; 126 } 127 mac_header_xmit = dev_is_mac_header_xmit(dev); 128 } else { 129 dev = NULL; 130 } 131 132 if (!exists) { 133 if (!dev) { 134 tcf_idr_cleanup(tn, parm->index); 135 NL_SET_ERR_MSG_MOD(extack, "Specified device does not exist"); 136 return -EINVAL; 137 } 138 ret = tcf_idr_create(tn, parm->index, est, a, 139 &act_mirred_ops, bind, true); 140 if (ret) { 141 tcf_idr_cleanup(tn, parm->index); 142 return ret; 143 } 144 ret = ACT_P_CREATED; 145 } else if (!ovr) { 146 tcf_idr_release(*a, bind); 147 return -EEXIST; 148 } 149 m = to_mirred(*a); 150 151 ASSERT_RTNL(); 152 m->tcf_action = parm->action; 153 m->tcfm_eaction = parm->eaction; 154 if (dev != NULL) { 155 if (ret != ACT_P_CREATED) 156 dev_put(rcu_dereference_protected(m->tcfm_dev, 1)); 157 dev_hold(dev); 158 rcu_assign_pointer(m->tcfm_dev, dev); 159 m->tcfm_mac_header_xmit = mac_header_xmit; 160 } 161 162 if (ret == ACT_P_CREATED) { 163 list_add(&m->tcfm_list, &mirred_list); 164 tcf_idr_insert(tn, *a); 165 } 166 167 return ret; 168 } 169 170 static int tcf_mirred(struct sk_buff *skb, const struct tc_action *a, 171 struct tcf_result *res) 172 { 173 struct tcf_mirred *m = to_mirred(a); 174 bool m_mac_header_xmit; 175 struct net_device *dev; 176 struct sk_buff *skb2; 177 int retval, err = 0; 178 int m_eaction; 179 int mac_len; 180 181 tcf_lastuse_update(&m->tcf_tm); 182 bstats_cpu_update(this_cpu_ptr(m->common.cpu_bstats), skb); 183 184 rcu_read_lock(); 185 m_mac_header_xmit = READ_ONCE(m->tcfm_mac_header_xmit); 186 m_eaction = READ_ONCE(m->tcfm_eaction); 187 retval = READ_ONCE(m->tcf_action); 188 dev = rcu_dereference(m->tcfm_dev); 189 if (unlikely(!dev)) { 190 pr_notice_once("tc mirred: target device is gone\n"); 191 goto out; 192 } 193 194 if (unlikely(!(dev->flags & IFF_UP))) { 195 net_notice_ratelimited("tc mirred to Houston: device %s is down\n", 196 dev->name); 197 goto out; 198 } 199 200 skb2 = skb_clone(skb, GFP_ATOMIC); 201 if (!skb2) 202 goto out; 203 204 /* If action's target direction differs than filter's direction, 205 * and devices expect a mac header on xmit, then mac push/pull is 206 * needed. 207 */ 208 if (skb_at_tc_ingress(skb) != tcf_mirred_act_wants_ingress(m_eaction) && 209 m_mac_header_xmit) { 210 if (!skb_at_tc_ingress(skb)) { 211 /* caught at egress, act ingress: pull mac */ 212 mac_len = skb_network_header(skb) - skb_mac_header(skb); 213 skb_pull_rcsum(skb2, mac_len); 214 } else { 215 /* caught at ingress, act egress: push mac */ 216 skb_push_rcsum(skb2, skb->mac_len); 217 } 218 } 219 220 /* mirror is always swallowed */ 221 if (tcf_mirred_is_act_redirect(m_eaction)) { 222 skb2->tc_redirected = 1; 223 skb2->tc_from_ingress = skb2->tc_at_ingress; 224 } 225 226 skb2->skb_iif = skb->dev->ifindex; 227 skb2->dev = dev; 228 if (!tcf_mirred_act_wants_ingress(m_eaction)) 229 err = dev_queue_xmit(skb2); 230 else 231 err = netif_receive_skb(skb2); 232 233 if (err) { 234 out: 235 qstats_overlimit_inc(this_cpu_ptr(m->common.cpu_qstats)); 236 if (tcf_mirred_is_act_redirect(m_eaction)) 237 retval = TC_ACT_SHOT; 238 } 239 rcu_read_unlock(); 240 241 return retval; 242 } 243 244 static void tcf_stats_update(struct tc_action *a, u64 bytes, u32 packets, 245 u64 lastuse) 246 { 247 struct tcf_mirred *m = to_mirred(a); 248 struct tcf_t *tm = &m->tcf_tm; 249 250 _bstats_cpu_update(this_cpu_ptr(a->cpu_bstats), bytes, packets); 251 tm->lastuse = max_t(u64, tm->lastuse, lastuse); 252 } 253 254 static int tcf_mirred_dump(struct sk_buff *skb, struct tc_action *a, int bind, 255 int ref) 256 { 257 unsigned char *b = skb_tail_pointer(skb); 258 struct tcf_mirred *m = to_mirred(a); 259 struct net_device *dev = rtnl_dereference(m->tcfm_dev); 260 struct tc_mirred opt = { 261 .index = m->tcf_index, 262 .action = m->tcf_action, 263 .refcnt = refcount_read(&m->tcf_refcnt) - ref, 264 .bindcnt = atomic_read(&m->tcf_bindcnt) - bind, 265 .eaction = m->tcfm_eaction, 266 .ifindex = dev ? dev->ifindex : 0, 267 }; 268 struct tcf_t t; 269 270 if (nla_put(skb, TCA_MIRRED_PARMS, sizeof(opt), &opt)) 271 goto nla_put_failure; 272 273 tcf_tm_dump(&t, &m->tcf_tm); 274 if (nla_put_64bit(skb, TCA_MIRRED_TM, sizeof(t), &t, TCA_MIRRED_PAD)) 275 goto nla_put_failure; 276 return skb->len; 277 278 nla_put_failure: 279 nlmsg_trim(skb, b); 280 return -1; 281 } 282 283 static int tcf_mirred_walker(struct net *net, struct sk_buff *skb, 284 struct netlink_callback *cb, int type, 285 const struct tc_action_ops *ops, 286 struct netlink_ext_ack *extack) 287 { 288 struct tc_action_net *tn = net_generic(net, mirred_net_id); 289 290 return tcf_generic_walker(tn, skb, cb, type, ops, extack); 291 } 292 293 static int tcf_mirred_search(struct net *net, struct tc_action **a, u32 index, 294 struct netlink_ext_ack *extack) 295 { 296 struct tc_action_net *tn = net_generic(net, mirred_net_id); 297 298 return tcf_idr_search(tn, a, index); 299 } 300 301 static int mirred_device_event(struct notifier_block *unused, 302 unsigned long event, void *ptr) 303 { 304 struct net_device *dev = netdev_notifier_info_to_dev(ptr); 305 struct tcf_mirred *m; 306 307 ASSERT_RTNL(); 308 if (event == NETDEV_UNREGISTER) { 309 list_for_each_entry(m, &mirred_list, tcfm_list) { 310 if (rcu_access_pointer(m->tcfm_dev) == dev) { 311 dev_put(dev); 312 /* Note : no rcu grace period necessary, as 313 * net_device are already rcu protected. 314 */ 315 RCU_INIT_POINTER(m->tcfm_dev, NULL); 316 } 317 } 318 } 319 320 return NOTIFY_DONE; 321 } 322 323 static struct notifier_block mirred_device_notifier = { 324 .notifier_call = mirred_device_event, 325 }; 326 327 static struct net_device *tcf_mirred_get_dev(const struct tc_action *a) 328 { 329 struct tcf_mirred *m = to_mirred(a); 330 331 return rtnl_dereference(m->tcfm_dev); 332 } 333 334 static int tcf_mirred_delete(struct net *net, u32 index) 335 { 336 struct tc_action_net *tn = net_generic(net, mirred_net_id); 337 338 return tcf_idr_delete_index(tn, index); 339 } 340 341 static struct tc_action_ops act_mirred_ops = { 342 .kind = "mirred", 343 .type = TCA_ACT_MIRRED, 344 .owner = THIS_MODULE, 345 .act = tcf_mirred, 346 .stats_update = tcf_stats_update, 347 .dump = tcf_mirred_dump, 348 .cleanup = tcf_mirred_release, 349 .init = tcf_mirred_init, 350 .walk = tcf_mirred_walker, 351 .lookup = tcf_mirred_search, 352 .size = sizeof(struct tcf_mirred), 353 .get_dev = tcf_mirred_get_dev, 354 .delete = tcf_mirred_delete, 355 }; 356 357 static __net_init int mirred_init_net(struct net *net) 358 { 359 struct tc_action_net *tn = net_generic(net, mirred_net_id); 360 361 return tc_action_net_init(tn, &act_mirred_ops); 362 } 363 364 static void __net_exit mirred_exit_net(struct list_head *net_list) 365 { 366 tc_action_net_exit(net_list, mirred_net_id); 367 } 368 369 static struct pernet_operations mirred_net_ops = { 370 .init = mirred_init_net, 371 .exit_batch = mirred_exit_net, 372 .id = &mirred_net_id, 373 .size = sizeof(struct tc_action_net), 374 }; 375 376 MODULE_AUTHOR("Jamal Hadi Salim(2002)"); 377 MODULE_DESCRIPTION("Device Mirror/redirect actions"); 378 MODULE_LICENSE("GPL"); 379 380 static int __init mirred_init_module(void) 381 { 382 int err = register_netdevice_notifier(&mirred_device_notifier); 383 if (err) 384 return err; 385 386 pr_info("Mirror/redirect action on\n"); 387 return tcf_register_action(&act_mirred_ops, &mirred_net_ops); 388 } 389 390 static void __exit mirred_cleanup_module(void) 391 { 392 tcf_unregister_action(&act_mirred_ops, &mirred_net_ops); 393 unregister_netdevice_notifier(&mirred_device_notifier); 394 } 395 396 module_init(mirred_init_module); 397 module_exit(mirred_cleanup_module); 398