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, int ovr, 72 int bind, struct netlink_ext_ack *extack) 73 { 74 struct tc_action_net *tn = net_generic(net, mirred_net_id); 75 struct nlattr *tb[TCA_MIRRED_MAX + 1]; 76 bool mac_header_xmit = false; 77 struct tc_mirred *parm; 78 struct tcf_mirred *m; 79 struct net_device *dev; 80 bool exists = false; 81 int ret; 82 83 if (!nla) { 84 NL_SET_ERR_MSG_MOD(extack, "Mirred requires attributes to be passed"); 85 return -EINVAL; 86 } 87 ret = nla_parse_nested(tb, TCA_MIRRED_MAX, nla, mirred_policy, extack); 88 if (ret < 0) 89 return ret; 90 if (!tb[TCA_MIRRED_PARMS]) { 91 NL_SET_ERR_MSG_MOD(extack, "Missing required mirred parameters"); 92 return -EINVAL; 93 } 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 NL_SET_ERR_MSG_MOD(extack, "Unknown mirred option"); 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_idr_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) { 126 NL_SET_ERR_MSG_MOD(extack, "Specified device does not exist"); 127 return -EINVAL; 128 } 129 ret = tcf_idr_create(tn, parm->index, est, a, 130 &act_mirred_ops, bind, true); 131 if (ret) 132 return ret; 133 ret = ACT_P_CREATED; 134 } else { 135 tcf_idr_release(*a, bind); 136 if (!ovr) 137 return -EEXIST; 138 } 139 m = to_mirred(*a); 140 141 ASSERT_RTNL(); 142 m->tcf_action = parm->action; 143 m->tcfm_eaction = parm->eaction; 144 if (dev != NULL) { 145 if (ret != ACT_P_CREATED) 146 dev_put(rcu_dereference_protected(m->tcfm_dev, 1)); 147 dev_hold(dev); 148 rcu_assign_pointer(m->tcfm_dev, dev); 149 m->tcfm_mac_header_xmit = mac_header_xmit; 150 } 151 152 if (ret == ACT_P_CREATED) { 153 list_add(&m->tcfm_list, &mirred_list); 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 = max_t(u64, 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 net_device *dev = rtnl_dereference(m->tcfm_dev); 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 = dev ? dev->ifindex : 0, 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 struct netlink_ext_ack *extack) 277 { 278 struct tc_action_net *tn = net_generic(net, mirred_net_id); 279 280 return tcf_generic_walker(tn, skb, cb, type, ops, extack); 281 } 282 283 static int tcf_mirred_search(struct net *net, struct tc_action **a, u32 index, 284 struct netlink_ext_ack *extack) 285 { 286 struct tc_action_net *tn = net_generic(net, mirred_net_id); 287 288 return tcf_idr_search(tn, a, index); 289 } 290 291 static int mirred_device_event(struct notifier_block *unused, 292 unsigned long event, void *ptr) 293 { 294 struct net_device *dev = netdev_notifier_info_to_dev(ptr); 295 struct tcf_mirred *m; 296 297 ASSERT_RTNL(); 298 if (event == NETDEV_UNREGISTER) { 299 list_for_each_entry(m, &mirred_list, tcfm_list) { 300 if (rcu_access_pointer(m->tcfm_dev) == dev) { 301 dev_put(dev); 302 /* Note : no rcu grace period necessary, as 303 * net_device are already rcu protected. 304 */ 305 RCU_INIT_POINTER(m->tcfm_dev, NULL); 306 } 307 } 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 struct net_device *tcf_mirred_get_dev(const struct tc_action *a) 318 { 319 struct tcf_mirred *m = to_mirred(a); 320 321 return rtnl_dereference(m->tcfm_dev); 322 } 323 324 static struct tc_action_ops act_mirred_ops = { 325 .kind = "mirred", 326 .type = TCA_ACT_MIRRED, 327 .owner = THIS_MODULE, 328 .act = tcf_mirred, 329 .stats_update = tcf_stats_update, 330 .dump = tcf_mirred_dump, 331 .cleanup = tcf_mirred_release, 332 .init = tcf_mirred_init, 333 .walk = tcf_mirred_walker, 334 .lookup = tcf_mirred_search, 335 .size = sizeof(struct tcf_mirred), 336 .get_dev = tcf_mirred_get_dev, 337 }; 338 339 static __net_init int mirred_init_net(struct net *net) 340 { 341 struct tc_action_net *tn = net_generic(net, mirred_net_id); 342 343 return tc_action_net_init(tn, &act_mirred_ops); 344 } 345 346 static void __net_exit mirred_exit_net(struct list_head *net_list) 347 { 348 tc_action_net_exit(net_list, mirred_net_id); 349 } 350 351 static struct pernet_operations mirred_net_ops = { 352 .init = mirred_init_net, 353 .exit_batch = mirred_exit_net, 354 .id = &mirred_net_id, 355 .size = sizeof(struct tc_action_net), 356 }; 357 358 MODULE_AUTHOR("Jamal Hadi Salim(2002)"); 359 MODULE_DESCRIPTION("Device Mirror/redirect actions"); 360 MODULE_LICENSE("GPL"); 361 362 static int __init mirred_init_module(void) 363 { 364 int err = register_netdevice_notifier(&mirred_device_notifier); 365 if (err) 366 return err; 367 368 pr_info("Mirror/redirect action on\n"); 369 return tcf_register_action(&act_mirred_ops, &mirred_net_ops); 370 } 371 372 static void __exit mirred_cleanup_module(void) 373 { 374 tcf_unregister_action(&act_mirred_ops, &mirred_net_ops); 375 unregister_netdevice_notifier(&mirred_device_notifier); 376 } 377 378 module_init(mirred_init_module); 379 module_exit(mirred_cleanup_module); 380