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_hurry(&ac->rcu, aca_free_rcu); 257 } 258 259 static struct ifacaddr6 *aca_alloc(struct fib6_info *f6i, 260 const struct in6_addr *addr) 261 { 262 struct ifacaddr6 *aca; 263 264 aca = kzalloc(sizeof(*aca), GFP_ATOMIC); 265 if (!aca) 266 return NULL; 267 268 aca->aca_addr = *addr; 269 fib6_info_hold(f6i); 270 aca->aca_rt = f6i; 271 INIT_HLIST_NODE(&aca->aca_addr_lst); 272 aca->aca_users = 1; 273 /* aca_tstamp should be updated upon changes */ 274 aca->aca_cstamp = aca->aca_tstamp = jiffies; 275 refcount_set(&aca->aca_refcnt, 1); 276 277 return aca; 278 } 279 280 /* 281 * device anycast group inc (add if not found) 282 */ 283 int __ipv6_dev_ac_inc(struct inet6_dev *idev, const struct in6_addr *addr) 284 { 285 struct ifacaddr6 *aca; 286 struct fib6_info *f6i; 287 struct net *net; 288 int err; 289 290 ASSERT_RTNL(); 291 292 write_lock_bh(&idev->lock); 293 if (idev->dead) { 294 err = -ENODEV; 295 goto out; 296 } 297 298 for (aca = rtnl_dereference(idev->ac_list); aca; 299 aca = rtnl_dereference(aca->aca_next)) { 300 if (ipv6_addr_equal(&aca->aca_addr, addr)) { 301 aca->aca_users++; 302 err = 0; 303 goto out; 304 } 305 } 306 307 net = dev_net(idev->dev); 308 f6i = addrconf_f6i_alloc(net, idev, addr, true, GFP_ATOMIC, NULL); 309 if (IS_ERR(f6i)) { 310 err = PTR_ERR(f6i); 311 goto out; 312 } 313 aca = aca_alloc(f6i, addr); 314 if (!aca) { 315 fib6_info_release(f6i); 316 err = -ENOMEM; 317 goto out; 318 } 319 320 /* Hold this for addrconf_join_solict() below before we unlock, 321 * it is already exposed via idev->ac_list. 322 */ 323 aca_get(aca); 324 aca->aca_next = idev->ac_list; 325 rcu_assign_pointer(idev->ac_list, aca); 326 327 write_unlock_bh(&idev->lock); 328 329 ipv6_add_acaddr_hash(net, aca); 330 331 ip6_ins_rt(net, f6i); 332 333 addrconf_join_solict(idev->dev, &aca->aca_addr); 334 335 aca_put(aca); 336 return 0; 337 out: 338 write_unlock_bh(&idev->lock); 339 return err; 340 } 341 342 /* 343 * device anycast group decrement 344 */ 345 int __ipv6_dev_ac_dec(struct inet6_dev *idev, const struct in6_addr *addr) 346 { 347 struct ifacaddr6 *aca, *prev_aca; 348 349 ASSERT_RTNL(); 350 351 write_lock_bh(&idev->lock); 352 prev_aca = NULL; 353 for (aca = rtnl_dereference(idev->ac_list); aca; 354 aca = rtnl_dereference(aca->aca_next)) { 355 if (ipv6_addr_equal(&aca->aca_addr, addr)) 356 break; 357 prev_aca = aca; 358 } 359 if (!aca) { 360 write_unlock_bh(&idev->lock); 361 return -ENOENT; 362 } 363 if (--aca->aca_users > 0) { 364 write_unlock_bh(&idev->lock); 365 return 0; 366 } 367 if (prev_aca) 368 rcu_assign_pointer(prev_aca->aca_next, aca->aca_next); 369 else 370 rcu_assign_pointer(idev->ac_list, aca->aca_next); 371 write_unlock_bh(&idev->lock); 372 ipv6_del_acaddr_hash(aca); 373 addrconf_leave_solict(idev, &aca->aca_addr); 374 375 ip6_del_rt(dev_net(idev->dev), aca->aca_rt, false); 376 377 aca_put(aca); 378 return 0; 379 } 380 381 /* called with rtnl_lock() */ 382 static int ipv6_dev_ac_dec(struct net_device *dev, const struct in6_addr *addr) 383 { 384 struct inet6_dev *idev = __in6_dev_get(dev); 385 386 if (!idev) 387 return -ENODEV; 388 return __ipv6_dev_ac_dec(idev, addr); 389 } 390 391 void ipv6_ac_destroy_dev(struct inet6_dev *idev) 392 { 393 struct ifacaddr6 *aca; 394 395 write_lock_bh(&idev->lock); 396 while ((aca = rtnl_dereference(idev->ac_list)) != NULL) { 397 rcu_assign_pointer(idev->ac_list, aca->aca_next); 398 write_unlock_bh(&idev->lock); 399 400 ipv6_del_acaddr_hash(aca); 401 402 addrconf_leave_solict(idev, &aca->aca_addr); 403 404 ip6_del_rt(dev_net(idev->dev), aca->aca_rt, false); 405 406 aca_put(aca); 407 408 write_lock_bh(&idev->lock); 409 } 410 write_unlock_bh(&idev->lock); 411 } 412 413 /* 414 * check if the interface has this anycast address 415 * called with rcu_read_lock() 416 */ 417 static bool ipv6_chk_acast_dev(struct net_device *dev, const struct in6_addr *addr) 418 { 419 struct inet6_dev *idev; 420 struct ifacaddr6 *aca; 421 422 idev = __in6_dev_get(dev); 423 if (idev) { 424 for (aca = rcu_dereference(idev->ac_list); aca; 425 aca = rcu_dereference(aca->aca_next)) 426 if (ipv6_addr_equal(&aca->aca_addr, addr)) 427 break; 428 return aca != NULL; 429 } 430 return false; 431 } 432 433 /* 434 * check if given interface (or any, if dev==0) has this anycast address 435 */ 436 bool ipv6_chk_acast_addr(struct net *net, struct net_device *dev, 437 const struct in6_addr *addr) 438 { 439 struct net_device *nh_dev; 440 struct ifacaddr6 *aca; 441 bool found = false; 442 443 rcu_read_lock(); 444 if (dev) 445 found = ipv6_chk_acast_dev(dev, addr); 446 else { 447 unsigned int hash = inet6_acaddr_hash(net, addr); 448 449 hlist_for_each_entry_rcu(aca, &inet6_acaddr_lst[hash], 450 aca_addr_lst) { 451 nh_dev = fib6_info_nh_dev(aca->aca_rt); 452 if (!nh_dev || !net_eq(dev_net(nh_dev), net)) 453 continue; 454 if (ipv6_addr_equal(&aca->aca_addr, addr)) { 455 found = true; 456 break; 457 } 458 } 459 } 460 rcu_read_unlock(); 461 return found; 462 } 463 464 /* check if this anycast address is link-local on given interface or 465 * is global 466 */ 467 bool ipv6_chk_acast_addr_src(struct net *net, struct net_device *dev, 468 const struct in6_addr *addr) 469 { 470 return ipv6_chk_acast_addr(net, 471 (ipv6_addr_type(addr) & IPV6_ADDR_LINKLOCAL ? 472 dev : NULL), 473 addr); 474 } 475 476 #ifdef CONFIG_PROC_FS 477 struct ac6_iter_state { 478 struct seq_net_private p; 479 struct net_device *dev; 480 }; 481 482 #define ac6_seq_private(seq) ((struct ac6_iter_state *)(seq)->private) 483 484 static inline struct ifacaddr6 *ac6_get_first(struct seq_file *seq) 485 { 486 struct ac6_iter_state *state = ac6_seq_private(seq); 487 struct net *net = seq_file_net(seq); 488 struct ifacaddr6 *im = NULL; 489 490 for_each_netdev_rcu(net, state->dev) { 491 struct inet6_dev *idev; 492 493 idev = __in6_dev_get(state->dev); 494 if (!idev) 495 continue; 496 im = rcu_dereference(idev->ac_list); 497 if (im) 498 break; 499 } 500 return im; 501 } 502 503 static struct ifacaddr6 *ac6_get_next(struct seq_file *seq, struct ifacaddr6 *im) 504 { 505 struct ac6_iter_state *state = ac6_seq_private(seq); 506 struct inet6_dev *idev; 507 508 im = rcu_dereference(im->aca_next); 509 while (!im) { 510 state->dev = next_net_device_rcu(state->dev); 511 if (!state->dev) 512 break; 513 idev = __in6_dev_get(state->dev); 514 if (!idev) 515 continue; 516 im = rcu_dereference(idev->ac_list); 517 } 518 return im; 519 } 520 521 static struct ifacaddr6 *ac6_get_idx(struct seq_file *seq, loff_t pos) 522 { 523 struct ifacaddr6 *im = ac6_get_first(seq); 524 if (im) 525 while (pos && (im = ac6_get_next(seq, im)) != NULL) 526 --pos; 527 return pos ? NULL : im; 528 } 529 530 static void *ac6_seq_start(struct seq_file *seq, loff_t *pos) 531 __acquires(RCU) 532 { 533 rcu_read_lock(); 534 return ac6_get_idx(seq, *pos); 535 } 536 537 static void *ac6_seq_next(struct seq_file *seq, void *v, loff_t *pos) 538 { 539 struct ifacaddr6 *im = ac6_get_next(seq, v); 540 541 ++*pos; 542 return im; 543 } 544 545 static void ac6_seq_stop(struct seq_file *seq, void *v) 546 __releases(RCU) 547 { 548 rcu_read_unlock(); 549 } 550 551 static int ac6_seq_show(struct seq_file *seq, void *v) 552 { 553 struct ifacaddr6 *im = (struct ifacaddr6 *)v; 554 struct ac6_iter_state *state = ac6_seq_private(seq); 555 556 seq_printf(seq, "%-4d %-15s %pi6 %5d\n", 557 state->dev->ifindex, state->dev->name, 558 &im->aca_addr, im->aca_users); 559 return 0; 560 } 561 562 static const struct seq_operations ac6_seq_ops = { 563 .start = ac6_seq_start, 564 .next = ac6_seq_next, 565 .stop = ac6_seq_stop, 566 .show = ac6_seq_show, 567 }; 568 569 int __net_init ac6_proc_init(struct net *net) 570 { 571 if (!proc_create_net("anycast6", 0444, net->proc_net, &ac6_seq_ops, 572 sizeof(struct ac6_iter_state))) 573 return -ENOMEM; 574 575 return 0; 576 } 577 578 void ac6_proc_exit(struct net *net) 579 { 580 remove_proc_entry("anycast6", net->proc_net); 581 } 582 #endif 583 584 /* Init / cleanup code 585 */ 586 int __init ipv6_anycast_init(void) 587 { 588 int i; 589 590 for (i = 0; i < IN6_ADDR_HSIZE; i++) 591 INIT_HLIST_HEAD(&inet6_acaddr_lst[i]); 592 return 0; 593 } 594 595 void ipv6_anycast_cleanup(void) 596 { 597 int i; 598 599 spin_lock(&acaddr_hash_lock); 600 for (i = 0; i < IN6_ADDR_HSIZE; i++) 601 WARN_ON(!hlist_empty(&inet6_acaddr_lst[i])); 602 spin_unlock(&acaddr_hash_lock); 603 } 604