1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Anycast support for IPv6 4 * Linux INET6 implementation 5 * 6 * Authors: 7 * David L Stevens (dlstevens@us.ibm.com) 8 * 9 * based heavily on net/ipv6/mcast.c 10 */ 11 12 #include <linux/capability.h> 13 #include <linux/module.h> 14 #include <linux/errno.h> 15 #include <linux/types.h> 16 #include <linux/random.h> 17 #include <linux/string.h> 18 #include <linux/socket.h> 19 #include <linux/sockios.h> 20 #include <linux/net.h> 21 #include <linux/in6.h> 22 #include <linux/netdevice.h> 23 #include <linux/if_arp.h> 24 #include <linux/route.h> 25 #include <linux/init.h> 26 #include <linux/proc_fs.h> 27 #include <linux/seq_file.h> 28 #include <linux/slab.h> 29 30 #include <net/net_namespace.h> 31 #include <net/sock.h> 32 #include <net/snmp.h> 33 34 #include <net/ipv6.h> 35 #include <net/protocol.h> 36 #include <net/if_inet6.h> 37 #include <net/ndisc.h> 38 #include <net/addrconf.h> 39 #include <net/ip6_route.h> 40 41 #include <net/checksum.h> 42 43 #define IN6_ADDR_HSIZE_SHIFT 8 44 #define IN6_ADDR_HSIZE BIT(IN6_ADDR_HSIZE_SHIFT) 45 /* anycast address hash table 46 */ 47 static struct hlist_head inet6_acaddr_lst[IN6_ADDR_HSIZE]; 48 static DEFINE_SPINLOCK(acaddr_hash_lock); 49 50 #define ac_dereference(a, idev) \ 51 rcu_dereference_protected(a, lockdep_is_held(&(idev)->lock)) 52 53 static int ipv6_dev_ac_dec(struct net_device *dev, const struct in6_addr *addr); 54 55 static u32 inet6_acaddr_hash(const struct net *net, 56 const struct in6_addr *addr) 57 { 58 u32 val = __ipv6_addr_jhash(addr, net_hash_mix(net)); 59 60 return hash_32(val, IN6_ADDR_HSIZE_SHIFT); 61 } 62 63 /* 64 * socket join an anycast group 65 */ 66 67 int ipv6_sock_ac_join(struct sock *sk, int ifindex, const struct in6_addr *addr) 68 { 69 struct ipv6_pinfo *np = inet6_sk(sk); 70 struct ipv6_ac_socklist *pac = NULL; 71 struct net *net = sock_net(sk); 72 netdevice_tracker dev_tracker; 73 struct net_device *dev = NULL; 74 struct inet6_dev *idev; 75 int err = 0, ishost; 76 77 if (!ns_capable(net->user_ns, CAP_NET_ADMIN)) 78 return -EPERM; 79 if (ipv6_addr_is_multicast(addr)) 80 return -EINVAL; 81 82 if (ifindex) 83 dev = netdev_get_by_index(net, ifindex, &dev_tracker, GFP_KERNEL); 84 85 if (ipv6_chk_addr_and_flags(net, addr, dev, true, 0, IFA_F_TENTATIVE)) { 86 err = -EINVAL; 87 goto error; 88 } 89 90 pac = sock_kmalloc(sk, sizeof(struct ipv6_ac_socklist), GFP_KERNEL); 91 if (!pac) { 92 err = -ENOMEM; 93 goto error; 94 } 95 96 pac->acl_next = NULL; 97 pac->acl_addr = *addr; 98 99 ishost = !READ_ONCE(net->ipv6.devconf_all->forwarding); 100 101 if (ifindex == 0) { 102 struct rt6_info *rt; 103 104 rcu_read_lock(); 105 rt = rt6_lookup(net, addr, NULL, 0, NULL, 0); 106 if (rt) { 107 dev = dst_dev(&rt->dst); 108 netdev_hold(dev, &dev_tracker, GFP_ATOMIC); 109 ip6_rt_put(rt); 110 } else if (ishost) { 111 rcu_read_unlock(); 112 err = -EADDRNOTAVAIL; 113 goto error; 114 } else { 115 /* router, no matching interface: just pick one */ 116 dev = netdev_get_by_flags_rcu(net, &dev_tracker, IFF_UP, 117 IFF_UP | IFF_LOOPBACK); 118 } 119 rcu_read_unlock(); 120 } 121 122 if (!dev) { 123 err = -ENODEV; 124 goto error; 125 } 126 127 idev = in6_dev_get(dev); 128 if (!idev) { 129 if (ifindex) 130 err = -ENODEV; 131 else 132 err = -EADDRNOTAVAIL; 133 goto error; 134 } 135 136 /* reset ishost, now that we have a specific device */ 137 ishost = !READ_ONCE(idev->cnf.forwarding); 138 139 pac->acl_ifindex = dev->ifindex; 140 141 /* XXX 142 * For hosts, allow link-local or matching prefix anycasts. 143 * This obviates the need for propagating anycast routes while 144 * still allowing some non-router anycast participation. 145 */ 146 if (!ipv6_chk_prefix(addr, dev)) { 147 if (ishost) 148 err = -EADDRNOTAVAIL; 149 if (err) 150 goto error_idev; 151 } 152 153 err = __ipv6_dev_ac_inc(idev, addr); 154 if (!err) { 155 pac->acl_next = np->ipv6_ac_list; 156 np->ipv6_ac_list = pac; 157 pac = NULL; 158 } 159 160 error_idev: 161 in6_dev_put(idev); 162 error: 163 netdev_put(dev, &dev_tracker); 164 165 if (pac) 166 sock_kfree_s(sk, pac, sizeof(*pac)); 167 return err; 168 } 169 170 /* 171 * socket leave an anycast group 172 */ 173 int ipv6_sock_ac_drop(struct sock *sk, int ifindex, const struct in6_addr *addr) 174 { 175 struct ipv6_ac_socklist *pac, *prev_pac; 176 struct ipv6_pinfo *np = inet6_sk(sk); 177 struct net *net = sock_net(sk); 178 struct net_device *dev; 179 180 prev_pac = NULL; 181 for (pac = np->ipv6_ac_list; pac; pac = pac->acl_next) { 182 if ((ifindex == 0 || pac->acl_ifindex == ifindex) && 183 ipv6_addr_equal(&pac->acl_addr, addr)) 184 break; 185 prev_pac = pac; 186 } 187 if (!pac) 188 return -ENOENT; 189 if (prev_pac) 190 prev_pac->acl_next = pac->acl_next; 191 else 192 np->ipv6_ac_list = pac->acl_next; 193 194 dev = dev_get_by_index(net, pac->acl_ifindex); 195 if (dev) { 196 ipv6_dev_ac_dec(dev, &pac->acl_addr); 197 dev_put(dev); 198 } 199 200 sock_kfree_s(sk, pac, sizeof(*pac)); 201 return 0; 202 } 203 204 void __ipv6_sock_ac_close(struct sock *sk) 205 { 206 struct ipv6_pinfo *np = inet6_sk(sk); 207 struct net *net = sock_net(sk); 208 struct net_device *dev = NULL; 209 struct ipv6_ac_socklist *pac; 210 int prev_index = 0; 211 212 pac = np->ipv6_ac_list; 213 np->ipv6_ac_list = NULL; 214 215 while (pac) { 216 struct ipv6_ac_socklist *next = pac->acl_next; 217 218 if (pac->acl_ifindex != prev_index) { 219 dev_put(dev); 220 dev = dev_get_by_index(net, pac->acl_ifindex); 221 prev_index = pac->acl_ifindex; 222 } 223 if (dev) 224 ipv6_dev_ac_dec(dev, &pac->acl_addr); 225 sock_kfree_s(sk, pac, sizeof(*pac)); 226 pac = next; 227 } 228 229 dev_put(dev); 230 } 231 232 void ipv6_sock_ac_close(struct sock *sk) 233 { 234 struct ipv6_pinfo *np = inet6_sk(sk); 235 236 if (!np->ipv6_ac_list) 237 return; 238 239 __ipv6_sock_ac_close(sk); 240 } 241 242 static void ipv6_add_acaddr_hash(struct net *net, struct ifacaddr6 *aca) 243 { 244 unsigned int hash = inet6_acaddr_hash(net, &aca->aca_addr); 245 246 spin_lock(&acaddr_hash_lock); 247 hlist_add_head_rcu(&aca->aca_addr_lst, &inet6_acaddr_lst[hash]); 248 spin_unlock(&acaddr_hash_lock); 249 } 250 251 static void ipv6_del_acaddr_hash(struct ifacaddr6 *aca) 252 { 253 spin_lock(&acaddr_hash_lock); 254 hlist_del_init_rcu(&aca->aca_addr_lst); 255 spin_unlock(&acaddr_hash_lock); 256 } 257 258 static void aca_get(struct ifacaddr6 *aca) 259 { 260 refcount_inc(&aca->aca_refcnt); 261 } 262 263 static void aca_free_rcu(struct rcu_head *h) 264 { 265 struct ifacaddr6 *aca = container_of(h, struct ifacaddr6, rcu); 266 267 fib6_info_release(aca->aca_rt); 268 kfree(aca); 269 } 270 271 static void aca_put(struct ifacaddr6 *ac) 272 { 273 if (refcount_dec_and_test(&ac->aca_refcnt)) 274 call_rcu_hurry(&ac->rcu, aca_free_rcu); 275 } 276 277 static struct ifacaddr6 *aca_alloc(struct fib6_info *f6i, 278 const struct in6_addr *addr) 279 { 280 struct ifacaddr6 *aca; 281 282 aca = kzalloc(sizeof(*aca), GFP_ATOMIC); 283 if (!aca) 284 return NULL; 285 286 aca->aca_addr = *addr; 287 fib6_info_hold(f6i); 288 aca->aca_rt = f6i; 289 INIT_HLIST_NODE(&aca->aca_addr_lst); 290 aca->aca_users = 1; 291 /* aca_tstamp should be updated upon changes */ 292 aca->aca_cstamp = aca->aca_tstamp = jiffies; 293 refcount_set(&aca->aca_refcnt, 1); 294 295 return aca; 296 } 297 298 static void inet6_ifacaddr_notify(struct net_device *dev, 299 const struct ifacaddr6 *ifaca, int event) 300 { 301 struct inet6_fill_args fillargs = { 302 .event = event, 303 .netnsid = -1, 304 }; 305 struct net *net = dev_net(dev); 306 struct sk_buff *skb; 307 int err = -ENOMEM; 308 309 skb = nlmsg_new(NLMSG_ALIGN(sizeof(struct ifaddrmsg)) + 310 nla_total_size(sizeof(struct in6_addr)) + 311 nla_total_size(sizeof(struct ifa_cacheinfo)), 312 GFP_KERNEL); 313 if (!skb) 314 goto error; 315 316 err = inet6_fill_ifacaddr(skb, ifaca, &fillargs); 317 if (err < 0) { 318 pr_err("Failed to fill in anycast addresses (err %d)\n", err); 319 nlmsg_free(skb); 320 goto error; 321 } 322 323 rtnl_notify(skb, net, 0, RTNLGRP_IPV6_ACADDR, NULL, GFP_KERNEL); 324 return; 325 error: 326 rtnl_set_sk_err(net, RTNLGRP_IPV6_ACADDR, err); 327 } 328 329 /* 330 * device anycast group inc (add if not found) 331 */ 332 int __ipv6_dev_ac_inc(struct inet6_dev *idev, const struct in6_addr *addr) 333 { 334 struct ifacaddr6 *aca; 335 struct fib6_info *f6i; 336 struct net *net; 337 int err; 338 339 write_lock_bh(&idev->lock); 340 if (idev->dead) { 341 err = -ENODEV; 342 goto out; 343 } 344 345 for (aca = ac_dereference(idev->ac_list, idev); aca; 346 aca = ac_dereference(aca->aca_next, idev)) { 347 if (ipv6_addr_equal(&aca->aca_addr, addr)) { 348 aca->aca_users++; 349 err = 0; 350 goto out; 351 } 352 } 353 354 net = dev_net(idev->dev); 355 f6i = addrconf_f6i_alloc(net, idev, addr, true, GFP_ATOMIC, NULL); 356 if (IS_ERR(f6i)) { 357 err = PTR_ERR(f6i); 358 goto out; 359 } 360 aca = aca_alloc(f6i, addr); 361 if (!aca) { 362 fib6_info_release(f6i); 363 err = -ENOMEM; 364 goto out; 365 } 366 367 /* Hold this for addrconf_join_solict() below before we unlock, 368 * it is already exposed via idev->ac_list. 369 */ 370 aca_get(aca); 371 aca->aca_next = idev->ac_list; 372 rcu_assign_pointer(idev->ac_list, aca); 373 374 write_unlock_bh(&idev->lock); 375 376 ipv6_add_acaddr_hash(net, aca); 377 378 ip6_ins_rt(net, f6i); 379 380 addrconf_join_solict(idev->dev, &aca->aca_addr); 381 382 inet6_ifacaddr_notify(idev->dev, aca, RTM_NEWANYCAST); 383 384 aca_put(aca); 385 return 0; 386 out: 387 write_unlock_bh(&idev->lock); 388 return err; 389 } 390 391 /* 392 * device anycast group decrement 393 */ 394 int __ipv6_dev_ac_dec(struct inet6_dev *idev, const struct in6_addr *addr) 395 { 396 struct ifacaddr6 *aca, *prev_aca; 397 398 write_lock_bh(&idev->lock); 399 prev_aca = NULL; 400 for (aca = ac_dereference(idev->ac_list, idev); aca; 401 aca = ac_dereference(aca->aca_next, idev)) { 402 if (ipv6_addr_equal(&aca->aca_addr, addr)) 403 break; 404 prev_aca = aca; 405 } 406 if (!aca) { 407 write_unlock_bh(&idev->lock); 408 return -ENOENT; 409 } 410 if (--aca->aca_users > 0) { 411 write_unlock_bh(&idev->lock); 412 return 0; 413 } 414 if (prev_aca) 415 rcu_assign_pointer(prev_aca->aca_next, aca->aca_next); 416 else 417 rcu_assign_pointer(idev->ac_list, aca->aca_next); 418 write_unlock_bh(&idev->lock); 419 ipv6_del_acaddr_hash(aca); 420 addrconf_leave_solict(idev, &aca->aca_addr); 421 422 ip6_del_rt(dev_net(idev->dev), aca->aca_rt, false); 423 424 inet6_ifacaddr_notify(idev->dev, aca, RTM_DELANYCAST); 425 426 aca_put(aca); 427 return 0; 428 } 429 430 static int ipv6_dev_ac_dec(struct net_device *dev, const struct in6_addr *addr) 431 { 432 struct inet6_dev *idev = in6_dev_get(dev); 433 int err; 434 435 if (!idev) 436 return -ENODEV; 437 438 err = __ipv6_dev_ac_dec(idev, addr); 439 in6_dev_put(idev); 440 441 return err; 442 } 443 444 void ipv6_ac_destroy_dev(struct inet6_dev *idev) 445 { 446 struct ifacaddr6 *aca; 447 448 write_lock_bh(&idev->lock); 449 while ((aca = ac_dereference(idev->ac_list, idev)) != NULL) { 450 rcu_assign_pointer(idev->ac_list, aca->aca_next); 451 write_unlock_bh(&idev->lock); 452 453 ipv6_del_acaddr_hash(aca); 454 455 addrconf_leave_solict(idev, &aca->aca_addr); 456 457 ip6_del_rt(dev_net(idev->dev), aca->aca_rt, false); 458 459 aca_put(aca); 460 461 write_lock_bh(&idev->lock); 462 } 463 write_unlock_bh(&idev->lock); 464 } 465 466 /* 467 * check if the interface has this anycast address 468 * called with rcu_read_lock() 469 */ 470 static bool ipv6_chk_acast_dev(struct net_device *dev, const struct in6_addr *addr) 471 { 472 struct inet6_dev *idev; 473 struct ifacaddr6 *aca; 474 475 idev = __in6_dev_get(dev); 476 if (idev) { 477 for (aca = rcu_dereference(idev->ac_list); aca; 478 aca = rcu_dereference(aca->aca_next)) 479 if (ipv6_addr_equal(&aca->aca_addr, addr)) 480 break; 481 return aca != NULL; 482 } 483 return false; 484 } 485 486 /* 487 * check if given interface (or any, if dev==0) has this anycast address 488 */ 489 bool ipv6_chk_acast_addr(struct net *net, struct net_device *dev, 490 const struct in6_addr *addr) 491 { 492 struct net_device *nh_dev; 493 struct ifacaddr6 *aca; 494 bool found = false; 495 496 rcu_read_lock(); 497 if (dev) 498 found = ipv6_chk_acast_dev(dev, addr); 499 else { 500 unsigned int hash = inet6_acaddr_hash(net, addr); 501 502 hlist_for_each_entry_rcu(aca, &inet6_acaddr_lst[hash], 503 aca_addr_lst) { 504 nh_dev = fib6_info_nh_dev(aca->aca_rt); 505 if (!nh_dev || !net_eq(dev_net(nh_dev), net)) 506 continue; 507 if (ipv6_addr_equal(&aca->aca_addr, addr)) { 508 found = true; 509 break; 510 } 511 } 512 } 513 rcu_read_unlock(); 514 return found; 515 } 516 517 /* check if this anycast address is link-local on given interface or 518 * is global 519 */ 520 bool ipv6_chk_acast_addr_src(struct net *net, struct net_device *dev, 521 const struct in6_addr *addr) 522 { 523 return ipv6_chk_acast_addr(net, 524 (ipv6_addr_type(addr) & IPV6_ADDR_LINKLOCAL ? 525 dev : NULL), 526 addr); 527 } 528 529 #ifdef CONFIG_PROC_FS 530 struct ac6_iter_state { 531 struct seq_net_private p; 532 struct net_device *dev; 533 }; 534 535 #define ac6_seq_private(seq) ((struct ac6_iter_state *)(seq)->private) 536 537 static inline struct ifacaddr6 *ac6_get_first(struct seq_file *seq) 538 { 539 struct ac6_iter_state *state = ac6_seq_private(seq); 540 struct net *net = seq_file_net(seq); 541 struct ifacaddr6 *im = NULL; 542 543 for_each_netdev_rcu(net, state->dev) { 544 struct inet6_dev *idev; 545 546 idev = __in6_dev_get(state->dev); 547 if (!idev) 548 continue; 549 im = rcu_dereference(idev->ac_list); 550 if (im) 551 break; 552 } 553 return im; 554 } 555 556 static struct ifacaddr6 *ac6_get_next(struct seq_file *seq, struct ifacaddr6 *im) 557 { 558 struct ac6_iter_state *state = ac6_seq_private(seq); 559 struct inet6_dev *idev; 560 561 im = rcu_dereference(im->aca_next); 562 while (!im) { 563 state->dev = next_net_device_rcu(state->dev); 564 if (!state->dev) 565 break; 566 idev = __in6_dev_get(state->dev); 567 if (!idev) 568 continue; 569 im = rcu_dereference(idev->ac_list); 570 } 571 return im; 572 } 573 574 static struct ifacaddr6 *ac6_get_idx(struct seq_file *seq, loff_t pos) 575 { 576 struct ifacaddr6 *im = ac6_get_first(seq); 577 if (im) 578 while (pos && (im = ac6_get_next(seq, im)) != NULL) 579 --pos; 580 return pos ? NULL : im; 581 } 582 583 static void *ac6_seq_start(struct seq_file *seq, loff_t *pos) 584 __acquires(RCU) 585 { 586 rcu_read_lock(); 587 return ac6_get_idx(seq, *pos); 588 } 589 590 static void *ac6_seq_next(struct seq_file *seq, void *v, loff_t *pos) 591 { 592 struct ifacaddr6 *im = ac6_get_next(seq, v); 593 594 ++*pos; 595 return im; 596 } 597 598 static void ac6_seq_stop(struct seq_file *seq, void *v) 599 __releases(RCU) 600 { 601 rcu_read_unlock(); 602 } 603 604 static int ac6_seq_show(struct seq_file *seq, void *v) 605 { 606 struct ifacaddr6 *im = (struct ifacaddr6 *)v; 607 struct ac6_iter_state *state = ac6_seq_private(seq); 608 609 seq_printf(seq, "%-4d %-15s %pi6 %5d\n", 610 state->dev->ifindex, state->dev->name, 611 &im->aca_addr, im->aca_users); 612 return 0; 613 } 614 615 static const struct seq_operations ac6_seq_ops = { 616 .start = ac6_seq_start, 617 .next = ac6_seq_next, 618 .stop = ac6_seq_stop, 619 .show = ac6_seq_show, 620 }; 621 622 int __net_init ac6_proc_init(struct net *net) 623 { 624 if (!proc_create_net("anycast6", 0444, net->proc_net, &ac6_seq_ops, 625 sizeof(struct ac6_iter_state))) 626 return -ENOMEM; 627 628 return 0; 629 } 630 631 void ac6_proc_exit(struct net *net) 632 { 633 remove_proc_entry("anycast6", net->proc_net); 634 } 635 #endif 636 637 /* Init / cleanup code 638 */ 639 int __init ipv6_anycast_init(void) 640 { 641 int i; 642 643 for (i = 0; i < IN6_ADDR_HSIZE; i++) 644 INIT_HLIST_HEAD(&inet6_acaddr_lst[i]); 645 return 0; 646 } 647 648 void ipv6_anycast_cleanup(void) 649 { 650 int i; 651 652 spin_lock(&acaddr_hash_lock); 653 for (i = 0; i < IN6_ADDR_HSIZE; i++) 654 WARN_ON(!hlist_empty(&inet6_acaddr_lst[i])); 655 spin_unlock(&acaddr_hash_lock); 656 } 657