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 static int ipv6_dev_ac_dec(struct net_device *dev, const struct in6_addr *addr); 51 52 static u32 inet6_acaddr_hash(struct net *net, const struct in6_addr *addr) 53 { 54 u32 val = ipv6_addr_hash(addr) ^ net_hash_mix(net); 55 56 return hash_32(val, IN6_ADDR_HSIZE_SHIFT); 57 } 58 59 /* 60 * socket join an anycast group 61 */ 62 63 int ipv6_sock_ac_join(struct sock *sk, int ifindex, const struct in6_addr *addr) 64 { 65 struct ipv6_pinfo *np = inet6_sk(sk); 66 struct net_device *dev = NULL; 67 struct inet6_dev *idev; 68 struct ipv6_ac_socklist *pac; 69 struct net *net = sock_net(sk); 70 int ishost = !net->ipv6.devconf_all->forwarding; 71 int err = 0; 72 73 ASSERT_RTNL(); 74 75 if (!ns_capable(net->user_ns, CAP_NET_ADMIN)) 76 return -EPERM; 77 if (ipv6_addr_is_multicast(addr)) 78 return -EINVAL; 79 80 if (ifindex) 81 dev = __dev_get_by_index(net, ifindex); 82 83 if (ipv6_chk_addr_and_flags(net, addr, dev, true, 0, IFA_F_TENTATIVE)) 84 return -EINVAL; 85 86 pac = sock_kmalloc(sk, sizeof(struct ipv6_ac_socklist), GFP_KERNEL); 87 if (!pac) 88 return -ENOMEM; 89 pac->acl_next = NULL; 90 pac->acl_addr = *addr; 91 92 if (ifindex == 0) { 93 struct rt6_info *rt; 94 95 rt = rt6_lookup(net, addr, NULL, 0, NULL, 0); 96 if (rt) { 97 dev = rt->dst.dev; 98 ip6_rt_put(rt); 99 } else if (ishost) { 100 err = -EADDRNOTAVAIL; 101 goto error; 102 } else { 103 /* router, no matching interface: just pick one */ 104 dev = __dev_get_by_flags(net, IFF_UP, 105 IFF_UP | IFF_LOOPBACK); 106 } 107 } 108 109 if (!dev) { 110 err = -ENODEV; 111 goto error; 112 } 113 114 idev = __in6_dev_get(dev); 115 if (!idev) { 116 if (ifindex) 117 err = -ENODEV; 118 else 119 err = -EADDRNOTAVAIL; 120 goto error; 121 } 122 /* reset ishost, now that we have a specific device */ 123 ishost = !idev->cnf.forwarding; 124 125 pac->acl_ifindex = dev->ifindex; 126 127 /* XXX 128 * For hosts, allow link-local or matching prefix anycasts. 129 * This obviates the need for propagating anycast routes while 130 * still allowing some non-router anycast participation. 131 */ 132 if (!ipv6_chk_prefix(addr, dev)) { 133 if (ishost) 134 err = -EADDRNOTAVAIL; 135 if (err) 136 goto error; 137 } 138 139 err = __ipv6_dev_ac_inc(idev, addr); 140 if (!err) { 141 pac->acl_next = np->ipv6_ac_list; 142 np->ipv6_ac_list = pac; 143 pac = NULL; 144 } 145 146 error: 147 if (pac) 148 sock_kfree_s(sk, pac, sizeof(*pac)); 149 return err; 150 } 151 152 /* 153 * socket leave an anycast group 154 */ 155 int ipv6_sock_ac_drop(struct sock *sk, int ifindex, const struct in6_addr *addr) 156 { 157 struct ipv6_pinfo *np = inet6_sk(sk); 158 struct net_device *dev; 159 struct ipv6_ac_socklist *pac, *prev_pac; 160 struct net *net = sock_net(sk); 161 162 ASSERT_RTNL(); 163 164 prev_pac = NULL; 165 for (pac = np->ipv6_ac_list; pac; pac = pac->acl_next) { 166 if ((ifindex == 0 || pac->acl_ifindex == ifindex) && 167 ipv6_addr_equal(&pac->acl_addr, addr)) 168 break; 169 prev_pac = pac; 170 } 171 if (!pac) 172 return -ENOENT; 173 if (prev_pac) 174 prev_pac->acl_next = pac->acl_next; 175 else 176 np->ipv6_ac_list = pac->acl_next; 177 178 dev = __dev_get_by_index(net, pac->acl_ifindex); 179 if (dev) 180 ipv6_dev_ac_dec(dev, &pac->acl_addr); 181 182 sock_kfree_s(sk, pac, sizeof(*pac)); 183 return 0; 184 } 185 186 void __ipv6_sock_ac_close(struct sock *sk) 187 { 188 struct ipv6_pinfo *np = inet6_sk(sk); 189 struct net_device *dev = NULL; 190 struct ipv6_ac_socklist *pac; 191 struct net *net = sock_net(sk); 192 int prev_index; 193 194 ASSERT_RTNL(); 195 pac = np->ipv6_ac_list; 196 np->ipv6_ac_list = NULL; 197 198 prev_index = 0; 199 while (pac) { 200 struct ipv6_ac_socklist *next = pac->acl_next; 201 202 if (pac->acl_ifindex != prev_index) { 203 dev = __dev_get_by_index(net, pac->acl_ifindex); 204 prev_index = pac->acl_ifindex; 205 } 206 if (dev) 207 ipv6_dev_ac_dec(dev, &pac->acl_addr); 208 sock_kfree_s(sk, pac, sizeof(*pac)); 209 pac = next; 210 } 211 } 212 213 void ipv6_sock_ac_close(struct sock *sk) 214 { 215 struct ipv6_pinfo *np = inet6_sk(sk); 216 217 if (!np->ipv6_ac_list) 218 return; 219 rtnl_lock(); 220 __ipv6_sock_ac_close(sk); 221 rtnl_unlock(); 222 } 223 224 static void ipv6_add_acaddr_hash(struct net *net, struct ifacaddr6 *aca) 225 { 226 unsigned int hash = inet6_acaddr_hash(net, &aca->aca_addr); 227 228 spin_lock(&acaddr_hash_lock); 229 hlist_add_head_rcu(&aca->aca_addr_lst, &inet6_acaddr_lst[hash]); 230 spin_unlock(&acaddr_hash_lock); 231 } 232 233 static void ipv6_del_acaddr_hash(struct ifacaddr6 *aca) 234 { 235 spin_lock(&acaddr_hash_lock); 236 hlist_del_init_rcu(&aca->aca_addr_lst); 237 spin_unlock(&acaddr_hash_lock); 238 } 239 240 static void aca_get(struct ifacaddr6 *aca) 241 { 242 refcount_inc(&aca->aca_refcnt); 243 } 244 245 static void aca_free_rcu(struct rcu_head *h) 246 { 247 struct ifacaddr6 *aca = container_of(h, struct ifacaddr6, rcu); 248 249 fib6_info_release(aca->aca_rt); 250 kfree(aca); 251 } 252 253 static void aca_put(struct ifacaddr6 *ac) 254 { 255 if (refcount_dec_and_test(&ac->aca_refcnt)) { 256 call_rcu(&ac->rcu, aca_free_rcu); 257 } 258 } 259 260 static struct ifacaddr6 *aca_alloc(struct fib6_info *f6i, 261 const struct in6_addr *addr) 262 { 263 struct ifacaddr6 *aca; 264 265 aca = kzalloc(sizeof(*aca), GFP_ATOMIC); 266 if (!aca) 267 return NULL; 268 269 aca->aca_addr = *addr; 270 fib6_info_hold(f6i); 271 aca->aca_rt = f6i; 272 INIT_HLIST_NODE(&aca->aca_addr_lst); 273 aca->aca_users = 1; 274 /* aca_tstamp should be updated upon changes */ 275 aca->aca_cstamp = aca->aca_tstamp = jiffies; 276 refcount_set(&aca->aca_refcnt, 1); 277 278 return aca; 279 } 280 281 /* 282 * device anycast group inc (add if not found) 283 */ 284 int __ipv6_dev_ac_inc(struct inet6_dev *idev, const struct in6_addr *addr) 285 { 286 struct ifacaddr6 *aca; 287 struct fib6_info *f6i; 288 struct net *net; 289 int err; 290 291 ASSERT_RTNL(); 292 293 write_lock_bh(&idev->lock); 294 if (idev->dead) { 295 err = -ENODEV; 296 goto out; 297 } 298 299 for (aca = rtnl_dereference(idev->ac_list); aca; 300 aca = rtnl_dereference(aca->aca_next)) { 301 if (ipv6_addr_equal(&aca->aca_addr, addr)) { 302 aca->aca_users++; 303 err = 0; 304 goto out; 305 } 306 } 307 308 net = dev_net(idev->dev); 309 f6i = addrconf_f6i_alloc(net, idev, addr, true, GFP_ATOMIC, NULL); 310 if (IS_ERR(f6i)) { 311 err = PTR_ERR(f6i); 312 goto out; 313 } 314 aca = aca_alloc(f6i, addr); 315 if (!aca) { 316 fib6_info_release(f6i); 317 err = -ENOMEM; 318 goto out; 319 } 320 321 /* Hold this for addrconf_join_solict() below before we unlock, 322 * it is already exposed via idev->ac_list. 323 */ 324 aca_get(aca); 325 aca->aca_next = idev->ac_list; 326 rcu_assign_pointer(idev->ac_list, aca); 327 328 write_unlock_bh(&idev->lock); 329 330 ipv6_add_acaddr_hash(net, aca); 331 332 ip6_ins_rt(net, f6i); 333 334 addrconf_join_solict(idev->dev, &aca->aca_addr); 335 336 aca_put(aca); 337 return 0; 338 out: 339 write_unlock_bh(&idev->lock); 340 return err; 341 } 342 343 /* 344 * device anycast group decrement 345 */ 346 int __ipv6_dev_ac_dec(struct inet6_dev *idev, const struct in6_addr *addr) 347 { 348 struct ifacaddr6 *aca, *prev_aca; 349 350 ASSERT_RTNL(); 351 352 write_lock_bh(&idev->lock); 353 prev_aca = NULL; 354 for (aca = rtnl_dereference(idev->ac_list); aca; 355 aca = rtnl_dereference(aca->aca_next)) { 356 if (ipv6_addr_equal(&aca->aca_addr, addr)) 357 break; 358 prev_aca = aca; 359 } 360 if (!aca) { 361 write_unlock_bh(&idev->lock); 362 return -ENOENT; 363 } 364 if (--aca->aca_users > 0) { 365 write_unlock_bh(&idev->lock); 366 return 0; 367 } 368 if (prev_aca) 369 rcu_assign_pointer(prev_aca->aca_next, aca->aca_next); 370 else 371 rcu_assign_pointer(idev->ac_list, aca->aca_next); 372 write_unlock_bh(&idev->lock); 373 ipv6_del_acaddr_hash(aca); 374 addrconf_leave_solict(idev, &aca->aca_addr); 375 376 ip6_del_rt(dev_net(idev->dev), aca->aca_rt, false); 377 378 aca_put(aca); 379 return 0; 380 } 381 382 /* called with rtnl_lock() */ 383 static int ipv6_dev_ac_dec(struct net_device *dev, const struct in6_addr *addr) 384 { 385 struct inet6_dev *idev = __in6_dev_get(dev); 386 387 if (!idev) 388 return -ENODEV; 389 return __ipv6_dev_ac_dec(idev, addr); 390 } 391 392 void ipv6_ac_destroy_dev(struct inet6_dev *idev) 393 { 394 struct ifacaddr6 *aca; 395 396 write_lock_bh(&idev->lock); 397 while ((aca = rtnl_dereference(idev->ac_list)) != NULL) { 398 rcu_assign_pointer(idev->ac_list, aca->aca_next); 399 write_unlock_bh(&idev->lock); 400 401 ipv6_del_acaddr_hash(aca); 402 403 addrconf_leave_solict(idev, &aca->aca_addr); 404 405 ip6_del_rt(dev_net(idev->dev), aca->aca_rt, false); 406 407 aca_put(aca); 408 409 write_lock_bh(&idev->lock); 410 } 411 write_unlock_bh(&idev->lock); 412 } 413 414 /* 415 * check if the interface has this anycast address 416 * called with rcu_read_lock() 417 */ 418 static bool ipv6_chk_acast_dev(struct net_device *dev, const struct in6_addr *addr) 419 { 420 struct inet6_dev *idev; 421 struct ifacaddr6 *aca; 422 423 idev = __in6_dev_get(dev); 424 if (idev) { 425 for (aca = rcu_dereference(idev->ac_list); aca; 426 aca = rcu_dereference(aca->aca_next)) 427 if (ipv6_addr_equal(&aca->aca_addr, addr)) 428 break; 429 return aca != NULL; 430 } 431 return false; 432 } 433 434 /* 435 * check if given interface (or any, if dev==0) has this anycast address 436 */ 437 bool ipv6_chk_acast_addr(struct net *net, struct net_device *dev, 438 const struct in6_addr *addr) 439 { 440 struct net_device *nh_dev; 441 struct ifacaddr6 *aca; 442 bool found = false; 443 444 rcu_read_lock(); 445 if (dev) 446 found = ipv6_chk_acast_dev(dev, addr); 447 else { 448 unsigned int hash = inet6_acaddr_hash(net, addr); 449 450 hlist_for_each_entry_rcu(aca, &inet6_acaddr_lst[hash], 451 aca_addr_lst) { 452 nh_dev = fib6_info_nh_dev(aca->aca_rt); 453 if (!nh_dev || !net_eq(dev_net(nh_dev), net)) 454 continue; 455 if (ipv6_addr_equal(&aca->aca_addr, addr)) { 456 found = true; 457 break; 458 } 459 } 460 } 461 rcu_read_unlock(); 462 return found; 463 } 464 465 /* check if this anycast address is link-local on given interface or 466 * is global 467 */ 468 bool ipv6_chk_acast_addr_src(struct net *net, struct net_device *dev, 469 const struct in6_addr *addr) 470 { 471 return ipv6_chk_acast_addr(net, 472 (ipv6_addr_type(addr) & IPV6_ADDR_LINKLOCAL ? 473 dev : NULL), 474 addr); 475 } 476 477 #ifdef CONFIG_PROC_FS 478 struct ac6_iter_state { 479 struct seq_net_private p; 480 struct net_device *dev; 481 }; 482 483 #define ac6_seq_private(seq) ((struct ac6_iter_state *)(seq)->private) 484 485 static inline struct ifacaddr6 *ac6_get_first(struct seq_file *seq) 486 { 487 struct ac6_iter_state *state = ac6_seq_private(seq); 488 struct net *net = seq_file_net(seq); 489 struct ifacaddr6 *im = NULL; 490 491 for_each_netdev_rcu(net, state->dev) { 492 struct inet6_dev *idev; 493 494 idev = __in6_dev_get(state->dev); 495 if (!idev) 496 continue; 497 im = rcu_dereference(idev->ac_list); 498 if (im) 499 break; 500 } 501 return im; 502 } 503 504 static struct ifacaddr6 *ac6_get_next(struct seq_file *seq, struct ifacaddr6 *im) 505 { 506 struct ac6_iter_state *state = ac6_seq_private(seq); 507 struct inet6_dev *idev; 508 509 im = rcu_dereference(im->aca_next); 510 while (!im) { 511 state->dev = next_net_device_rcu(state->dev); 512 if (!state->dev) 513 break; 514 idev = __in6_dev_get(state->dev); 515 if (!idev) 516 continue; 517 im = rcu_dereference(idev->ac_list); 518 } 519 return im; 520 } 521 522 static struct ifacaddr6 *ac6_get_idx(struct seq_file *seq, loff_t pos) 523 { 524 struct ifacaddr6 *im = ac6_get_first(seq); 525 if (im) 526 while (pos && (im = ac6_get_next(seq, im)) != NULL) 527 --pos; 528 return pos ? NULL : im; 529 } 530 531 static void *ac6_seq_start(struct seq_file *seq, loff_t *pos) 532 __acquires(RCU) 533 { 534 rcu_read_lock(); 535 return ac6_get_idx(seq, *pos); 536 } 537 538 static void *ac6_seq_next(struct seq_file *seq, void *v, loff_t *pos) 539 { 540 struct ifacaddr6 *im = ac6_get_next(seq, v); 541 542 ++*pos; 543 return im; 544 } 545 546 static void ac6_seq_stop(struct seq_file *seq, void *v) 547 __releases(RCU) 548 { 549 rcu_read_unlock(); 550 } 551 552 static int ac6_seq_show(struct seq_file *seq, void *v) 553 { 554 struct ifacaddr6 *im = (struct ifacaddr6 *)v; 555 struct ac6_iter_state *state = ac6_seq_private(seq); 556 557 seq_printf(seq, "%-4d %-15s %pi6 %5d\n", 558 state->dev->ifindex, state->dev->name, 559 &im->aca_addr, im->aca_users); 560 return 0; 561 } 562 563 static const struct seq_operations ac6_seq_ops = { 564 .start = ac6_seq_start, 565 .next = ac6_seq_next, 566 .stop = ac6_seq_stop, 567 .show = ac6_seq_show, 568 }; 569 570 int __net_init ac6_proc_init(struct net *net) 571 { 572 if (!proc_create_net("anycast6", 0444, net->proc_net, &ac6_seq_ops, 573 sizeof(struct ac6_iter_state))) 574 return -ENOMEM; 575 576 return 0; 577 } 578 579 void ac6_proc_exit(struct net *net) 580 { 581 remove_proc_entry("anycast6", net->proc_net); 582 } 583 #endif 584 585 /* Init / cleanup code 586 */ 587 int __init ipv6_anycast_init(void) 588 { 589 int i; 590 591 for (i = 0; i < IN6_ADDR_HSIZE; i++) 592 INIT_HLIST_HEAD(&inet6_acaddr_lst[i]); 593 return 0; 594 } 595 596 void ipv6_anycast_cleanup(void) 597 { 598 int i; 599 600 spin_lock(&acaddr_hash_lock); 601 for (i = 0; i < IN6_ADDR_HSIZE; i++) 602 WARN_ON(!hlist_empty(&inet6_acaddr_lst[i])); 603 spin_unlock(&acaddr_hash_lock); 604 } 605