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; 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 exists = tcf_idr_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_idr_release(*a, bind); 110 NL_SET_ERR_MSG_MOD(extack, "Unknown mirred option"); 111 return -EINVAL; 112 } 113 if (parm->ifindex) { 114 dev = __dev_get_by_index(net, parm->ifindex); 115 if (dev == NULL) { 116 if (exists) 117 tcf_idr_release(*a, bind); 118 return -ENODEV; 119 } 120 mac_header_xmit = dev_is_mac_header_xmit(dev); 121 } else { 122 dev = NULL; 123 } 124 125 if (!exists) { 126 if (!dev) { 127 NL_SET_ERR_MSG_MOD(extack, "Specified device does not exist"); 128 return -EINVAL; 129 } 130 ret = tcf_idr_create(tn, parm->index, est, a, 131 &act_mirred_ops, bind, true); 132 if (ret) 133 return ret; 134 ret = ACT_P_CREATED; 135 } else { 136 tcf_idr_release(*a, bind); 137 if (!ovr) 138 return -EEXIST; 139 } 140 m = to_mirred(*a); 141 142 ASSERT_RTNL(); 143 m->tcf_action = parm->action; 144 m->tcfm_eaction = parm->eaction; 145 if (dev != NULL) { 146 if (ret != ACT_P_CREATED) 147 dev_put(rcu_dereference_protected(m->tcfm_dev, 1)); 148 dev_hold(dev); 149 rcu_assign_pointer(m->tcfm_dev, dev); 150 m->tcfm_mac_header_xmit = mac_header_xmit; 151 } 152 153 if (ret == ACT_P_CREATED) { 154 list_add(&m->tcfm_list, &mirred_list); 155 tcf_idr_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 = max_t(u64, 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 net_device *dev = rtnl_dereference(m->tcfm_dev); 251 struct tc_mirred opt = { 252 .index = m->tcf_index, 253 .action = m->tcf_action, 254 .refcnt = refcount_read(&m->tcf_refcnt) - ref, 255 .bindcnt = atomic_read(&m->tcf_bindcnt) - bind, 256 .eaction = m->tcfm_eaction, 257 .ifindex = dev ? dev->ifindex : 0, 258 }; 259 struct tcf_t t; 260 261 if (nla_put(skb, TCA_MIRRED_PARMS, sizeof(opt), &opt)) 262 goto nla_put_failure; 263 264 tcf_tm_dump(&t, &m->tcf_tm); 265 if (nla_put_64bit(skb, TCA_MIRRED_TM, sizeof(t), &t, TCA_MIRRED_PAD)) 266 goto nla_put_failure; 267 return skb->len; 268 269 nla_put_failure: 270 nlmsg_trim(skb, b); 271 return -1; 272 } 273 274 static int tcf_mirred_walker(struct net *net, struct sk_buff *skb, 275 struct netlink_callback *cb, int type, 276 const struct tc_action_ops *ops, 277 struct netlink_ext_ack *extack) 278 { 279 struct tc_action_net *tn = net_generic(net, mirred_net_id); 280 281 return tcf_generic_walker(tn, skb, cb, type, ops, extack); 282 } 283 284 static int tcf_mirred_search(struct net *net, struct tc_action **a, u32 index, 285 struct netlink_ext_ack *extack) 286 { 287 struct tc_action_net *tn = net_generic(net, mirred_net_id); 288 289 return tcf_idr_search(tn, a, index); 290 } 291 292 static int mirred_device_event(struct notifier_block *unused, 293 unsigned long event, void *ptr) 294 { 295 struct net_device *dev = netdev_notifier_info_to_dev(ptr); 296 struct tcf_mirred *m; 297 298 ASSERT_RTNL(); 299 if (event == NETDEV_UNREGISTER) { 300 list_for_each_entry(m, &mirred_list, tcfm_list) { 301 if (rcu_access_pointer(m->tcfm_dev) == dev) { 302 dev_put(dev); 303 /* Note : no rcu grace period necessary, as 304 * net_device are already rcu protected. 305 */ 306 RCU_INIT_POINTER(m->tcfm_dev, NULL); 307 } 308 } 309 } 310 311 return NOTIFY_DONE; 312 } 313 314 static struct notifier_block mirred_device_notifier = { 315 .notifier_call = mirred_device_event, 316 }; 317 318 static struct net_device *tcf_mirred_get_dev(const struct tc_action *a) 319 { 320 struct tcf_mirred *m = to_mirred(a); 321 322 return rtnl_dereference(m->tcfm_dev); 323 } 324 325 static int tcf_mirred_delete(struct net *net, u32 index) 326 { 327 struct tc_action_net *tn = net_generic(net, mirred_net_id); 328 329 return tcf_idr_delete_index(tn, index); 330 } 331 332 static struct tc_action_ops act_mirred_ops = { 333 .kind = "mirred", 334 .type = TCA_ACT_MIRRED, 335 .owner = THIS_MODULE, 336 .act = tcf_mirred, 337 .stats_update = tcf_stats_update, 338 .dump = tcf_mirred_dump, 339 .cleanup = tcf_mirred_release, 340 .init = tcf_mirred_init, 341 .walk = tcf_mirred_walker, 342 .lookup = tcf_mirred_search, 343 .size = sizeof(struct tcf_mirred), 344 .get_dev = tcf_mirred_get_dev, 345 .delete = tcf_mirred_delete, 346 }; 347 348 static __net_init int mirred_init_net(struct net *net) 349 { 350 struct tc_action_net *tn = net_generic(net, mirred_net_id); 351 352 return tc_action_net_init(tn, &act_mirred_ops); 353 } 354 355 static void __net_exit mirred_exit_net(struct list_head *net_list) 356 { 357 tc_action_net_exit(net_list, mirred_net_id); 358 } 359 360 static struct pernet_operations mirred_net_ops = { 361 .init = mirred_init_net, 362 .exit_batch = mirred_exit_net, 363 .id = &mirred_net_id, 364 .size = sizeof(struct tc_action_net), 365 }; 366 367 MODULE_AUTHOR("Jamal Hadi Salim(2002)"); 368 MODULE_DESCRIPTION("Device Mirror/redirect actions"); 369 MODULE_LICENSE("GPL"); 370 371 static int __init mirred_init_module(void) 372 { 373 int err = register_netdevice_notifier(&mirred_device_notifier); 374 if (err) 375 return err; 376 377 pr_info("Mirror/redirect action on\n"); 378 return tcf_register_action(&act_mirred_ops, &mirred_net_ops); 379 } 380 381 static void __exit mirred_cleanup_module(void) 382 { 383 tcf_unregister_action(&act_mirred_ops, &mirred_net_ops); 384 unregister_netdevice_notifier(&mirred_device_notifier); 385 } 386 387 module_init(mirred_init_module); 388 module_exit(mirred_cleanup_module); 389