net/ipv4/fib_semantics.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * INET         An implementation of the TCP/IP protocol suite for the LINUX
   4  *              operating system.  INET is implemented using the  BSD Socket
   5  *              interface as the means of communication with the user level.
   6  *
   7  *              IPv4 Forwarding Information Base: semantics.
   8  *
   9  * Authors:     Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
  10  */
  11
  12 #include <linux/uaccess.h>
  13 #include <linux/bitops.h>
  14 #include <linux/types.h>
  15 #include <linux/kernel.h>
  16 #include <linux/jiffies.h>
  17 #include <linux/mm.h>
  18 #include <linux/string.h>
  19 #include <linux/socket.h>
  20 #include <linux/sockios.h>
  21 #include <linux/errno.h>
  22 #include <linux/in.h>
  23 #include <linux/inet.h>
  24 #include <linux/inetdevice.h>
  25 #include <linux/netdevice.h>
  26 #include <linux/if_arp.h>
  27 #include <linux/proc_fs.h>
  28 #include <linux/skbuff.h>
  29 #include <linux/init.h>
  30 #include <linux/slab.h>
  31 #include <linux/netlink.h>
  32
  33 #include <net/arp.h>
  34 #include <net/ip.h>
  35 #include <net/protocol.h>
  36 #include <net/route.h>
  37 #include <net/tcp.h>
  38 #include <net/sock.h>
  39 #include <net/ip_fib.h>
  40 #include <net/ip6_fib.h>
  41 #include <net/nexthop.h>
  42 #include <net/netlink.h>
  43 #include <net/rtnh.h>
  44 #include <net/lwtunnel.h>
  45 #include <net/fib_notifier.h>
  46 #include <net/addrconf.h>
  47
  48 #include "fib_lookup.h"
  49
  50 static DEFINE_SPINLOCK(fib_info_lock);
  51 static struct hlist_head *fib_info_hash;
  52 static struct hlist_head *fib_info_laddrhash;
  53 static unsigned int fib_info_hash_size;
  54 static unsigned int fib_info_cnt;
  55
  56 #define DEVINDEX_HASHBITS 8
  57 #define DEVINDEX_HASHSIZE (1U << DEVINDEX_HASHBITS)
  58 static struct hlist_head fib_info_devhash[DEVINDEX_HASHSIZE];
  59
  60 /* for_nexthops and change_nexthops only used when nexthop object
  61  * is not set in a fib_info. The logic within can reference fib_nh.
  62  */
  63 #ifdef CONFIG_IP_ROUTE_MULTIPATH
  64
  65 #define for_nexthops(fi) {                                              \
  66         int nhsel; const struct fib_nh *nh;                             \
  67         for (nhsel = 0, nh = (fi)->fib_nh;                              \
  68              nhsel < fib_info_num_path((fi));                           \
  69              nh++, nhsel++)
  70
  71 #define change_nexthops(fi) {                                           \
  72         int nhsel; struct fib_nh *nexthop_nh;                           \
  73         for (nhsel = 0, nexthop_nh = (struct fib_nh *)((fi)->fib_nh);   \
  74              nhsel < fib_info_num_path((fi));                           \
  75              nexthop_nh++, nhsel++)
  76
  77 #else /* CONFIG_IP_ROUTE_MULTIPATH */
  78
  79 /* Hope, that gcc will optimize it to get rid of dummy loop */
  80
  81 #define for_nexthops(fi) {                                              \
  82         int nhsel; const struct fib_nh *nh = (fi)->fib_nh;              \
  83         for (nhsel = 0; nhsel < 1; nhsel++)
  84
  85 #define change_nexthops(fi) {                                           \
  86         int nhsel;                                                      \
  87         struct fib_nh *nexthop_nh = (struct fib_nh *)((fi)->fib_nh);    \
  88         for (nhsel = 0; nhsel < 1; nhsel++)
  89
  90 #endif /* CONFIG_IP_ROUTE_MULTIPATH */
  91
  92 #define endfor_nexthops(fi) }
  93
  94
  95 const struct fib_prop fib_props[RTN_MAX + 1] = {
  96         [RTN_UNSPEC] = {
  97                 .error  = 0,
  98                 .scope  = RT_SCOPE_NOWHERE,
  99         },
 100         [RTN_UNICAST] = {
 101                 .error  = 0,
 102                 .scope  = RT_SCOPE_UNIVERSE,
 103         },
 104         [RTN_LOCAL] = {
 105                 .error  = 0,
 106                 .scope  = RT_SCOPE_HOST,
 107         },
 108         [RTN_BROADCAST] = {
 109                 .error  = 0,
 110                 .scope  = RT_SCOPE_LINK,
 111         },
 112         [RTN_ANYCAST] = {
 113                 .error  = 0,
 114                 .scope  = RT_SCOPE_LINK,
 115         },
 116         [RTN_MULTICAST] = {
 117                 .error  = 0,
 118                 .scope  = RT_SCOPE_UNIVERSE,
 119         },
 120         [RTN_BLACKHOLE] = {
 121                 .error  = -EINVAL,
 122                 .scope  = RT_SCOPE_UNIVERSE,
 123         },
 124         [RTN_UNREACHABLE] = {
 125                 .error  = -EHOSTUNREACH,
 126                 .scope  = RT_SCOPE_UNIVERSE,
 127         },
 128         [RTN_PROHIBIT] = {
 129                 .error  = -EACCES,
 130                 .scope  = RT_SCOPE_UNIVERSE,
 131         },
 132         [RTN_THROW] = {
 133                 .error  = -EAGAIN,
 134                 .scope  = RT_SCOPE_UNIVERSE,
 135         },
 136         [RTN_NAT] = {
 137                 .error  = -EINVAL,
 138                 .scope  = RT_SCOPE_NOWHERE,
 139         },
 140         [RTN_XRESOLVE] = {
 141                 .error  = -EINVAL,
 142                 .scope  = RT_SCOPE_NOWHERE,
 143         },
 144 };
 145
 146 static void rt_fibinfo_free(struct rtable __rcu **rtp)
 147 {
 148         struct rtable *rt = rcu_dereference_protected(*rtp, 1);
 149
 150         if (!rt)
 151                 return;
 152
 153         /* Not even needed : RCU_INIT_POINTER(*rtp, NULL);
 154          * because we waited an RCU grace period before calling
 155          * free_fib_info_rcu()
 156          */
 157
 158         dst_dev_put(&rt->dst);
 159         dst_release_immediate(&rt->dst);
 160 }
 161
 162 static void free_nh_exceptions(struct fib_nh_common *nhc)
 163 {
 164         struct fnhe_hash_bucket *hash;
 165         int i;
 166
 167         hash = rcu_dereference_protected(nhc->nhc_exceptions, 1);
 168         if (!hash)
 169                 return;
 170         for (i = 0; i < FNHE_HASH_SIZE; i++) {
 171                 struct fib_nh_exception *fnhe;
 172
 173                 fnhe = rcu_dereference_protected(hash[i].chain, 1);
 174                 while (fnhe) {
 175                         struct fib_nh_exception *next;
 176
 177                         next = rcu_dereference_protected(fnhe->fnhe_next, 1);
 178
 179                         rt_fibinfo_free(&fnhe->fnhe_rth_input);
 180                         rt_fibinfo_free(&fnhe->fnhe_rth_output);
 181
 182                         kfree(fnhe);
 183
 184                         fnhe = next;
 185                 }
 186         }
 187         kfree(hash);
 188 }
 189
 190 static void rt_fibinfo_free_cpus(struct rtable __rcu * __percpu *rtp)
 191 {
 192         int cpu;
 193
 194         if (!rtp)
 195                 return;
 196
 197         for_each_possible_cpu(cpu) {
 198                 struct rtable *rt;
 199
 200                 rt = rcu_dereference_protected(*per_cpu_ptr(rtp, cpu), 1);
 201                 if (rt) {
 202                         dst_dev_put(&rt->dst);
 203                         dst_release_immediate(&rt->dst);
 204                 }
 205         }
 206         free_percpu(rtp);
 207 }
 208
 209 void fib_nh_common_release(struct fib_nh_common *nhc)
 210 {
 211         if (nhc->nhc_dev)
 212                 dev_put(nhc->nhc_dev);
 213
 214         lwtstate_put(nhc->nhc_lwtstate);
 215         rt_fibinfo_free_cpus(nhc->nhc_pcpu_rth_output);
 216         rt_fibinfo_free(&nhc->nhc_rth_input);
 217         free_nh_exceptions(nhc);
 218 }
 219 EXPORT_SYMBOL_GPL(fib_nh_common_release);
 220
 221 void fib_nh_release(struct net *net, struct fib_nh *fib_nh)
 222 {
 223 #ifdef CONFIG_IP_ROUTE_CLASSID
 224         if (fib_nh->nh_tclassid)
 225                 net->ipv4.fib_num_tclassid_users--;
 226 #endif
 227         fib_nh_common_release(&fib_nh->nh_common);
 228 }
 229
 230 /* Release a nexthop info record */
 231 static void free_fib_info_rcu(struct rcu_head *head)
 232 {
 233         struct fib_info *fi = container_of(head, struct fib_info, rcu);
 234
 235         if (fi->nh) {
 236                 nexthop_put(fi->nh);
 237         } else {
 238                 change_nexthops(fi) {
 239                         fib_nh_release(fi->fib_net, nexthop_nh);
 240                 } endfor_nexthops(fi);
 241         }
 242
 243         ip_fib_metrics_put(fi->fib_metrics);
 244
 245         kfree(fi);
 246 }
 247
 248 void free_fib_info(struct fib_info *fi)
 249 {
 250         if (fi->fib_dead == 0) {
 251                 pr_warn("Freeing alive fib_info %p\n", fi);
 252                 return;
 253         }
 254         fib_info_cnt--;
 255
 256         call_rcu(&fi->rcu, free_fib_info_rcu);
 257 }
 258 EXPORT_SYMBOL_GPL(free_fib_info);
 259
 260 void fib_release_info(struct fib_info *fi)
 261 {
 262         spin_lock_bh(&fib_info_lock);
 263         if (fi && --fi->fib_treeref == 0) {
 264                 hlist_del(&fi->fib_hash);
 265                 if (fi->fib_prefsrc)
 266                         hlist_del(&fi->fib_lhash);
 267                 if (fi->nh) {
 268                         list_del(&fi->nh_list);
 269                 } else {
 270                         change_nexthops(fi) {
 271                                 if (!nexthop_nh->fib_nh_dev)
 272                                         continue;
 273                                 hlist_del(&nexthop_nh->nh_hash);
 274                         } endfor_nexthops(fi)
 275                 }
 276                 fi->fib_dead = 1;
 277                 fib_info_put(fi);
 278         }
 279         spin_unlock_bh(&fib_info_lock);
 280 }
 281
 282 static inline int nh_comp(struct fib_info *fi, struct fib_info *ofi)
 283 {
 284         const struct fib_nh *onh;
 285
 286         if (fi->nh || ofi->nh)
 287                 return nexthop_cmp(fi->nh, ofi->nh) ? 0 : -1;
 288
 289         if (ofi->fib_nhs == 0)
 290                 return 0;
 291
 292         for_nexthops(fi) {
 293                 onh = fib_info_nh(ofi, nhsel);
 294
 295                 if (nh->fib_nh_oif != onh->fib_nh_oif ||
 296                     nh->fib_nh_gw_family != onh->fib_nh_gw_family ||
 297                     nh->fib_nh_scope != onh->fib_nh_scope ||
 298 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 299                     nh->fib_nh_weight != onh->fib_nh_weight ||
 300 #endif
 301 #ifdef CONFIG_IP_ROUTE_CLASSID
 302                     nh->nh_tclassid != onh->nh_tclassid ||
 303 #endif
 304                     lwtunnel_cmp_encap(nh->fib_nh_lws, onh->fib_nh_lws) ||
 305                     ((nh->fib_nh_flags ^ onh->fib_nh_flags) & ~RTNH_COMPARE_MASK))
 306                         return -1;
 307
 308                 if (nh->fib_nh_gw_family == AF_INET &&
 309                     nh->fib_nh_gw4 != onh->fib_nh_gw4)
 310                         return -1;
 311
 312                 if (nh->fib_nh_gw_family == AF_INET6 &&
 313                     ipv6_addr_cmp(&nh->fib_nh_gw6, &onh->fib_nh_gw6))
 314                         return -1;
 315         } endfor_nexthops(fi);
 316         return 0;
 317 }
 318
 319 static inline unsigned int fib_devindex_hashfn(unsigned int val)
 320 {
 321         unsigned int mask = DEVINDEX_HASHSIZE - 1;
 322
 323         return (val ^
 324                 (val >> DEVINDEX_HASHBITS) ^
 325                 (val >> (DEVINDEX_HASHBITS * 2))) & mask;
 326 }
 327
 328 static unsigned int fib_info_hashfn_1(int init_val, u8 protocol, u8 scope,
 329                                       u32 prefsrc, u32 priority)
 330 {
 331         unsigned int val = init_val;
 332
 333         val ^= (protocol << 8) | scope;
 334         val ^= prefsrc;
 335         val ^= priority;
 336
 337         return val;
 338 }
 339
 340 static unsigned int fib_info_hashfn_result(unsigned int val)
 341 {
 342         unsigned int mask = (fib_info_hash_size - 1);
 343
 344         return (val ^ (val >> 7) ^ (val >> 12)) & mask;
 345 }
 346
 347 static inline unsigned int fib_info_hashfn(struct fib_info *fi)
 348 {
 349         unsigned int val;
 350
 351         val = fib_info_hashfn_1(fi->fib_nhs, fi->fib_protocol,
 352                                 fi->fib_scope, (__force u32)fi->fib_prefsrc,
 353                                 fi->fib_priority);
 354
 355         if (fi->nh) {
 356                 val ^= fib_devindex_hashfn(fi->nh->id);
 357         } else {
 358                 for_nexthops(fi) {
 359                         val ^= fib_devindex_hashfn(nh->fib_nh_oif);
 360                 } endfor_nexthops(fi)
 361         }
 362
 363         return fib_info_hashfn_result(val);
 364 }
 365
 366 /* no metrics, only nexthop id */
 367 static struct fib_info *fib_find_info_nh(struct net *net,
 368                                          const struct fib_config *cfg)
 369 {
 370         struct hlist_head *head;
 371         struct fib_info *fi;
 372         unsigned int hash;
 373
 374         hash = fib_info_hashfn_1(fib_devindex_hashfn(cfg->fc_nh_id),
 375                                  cfg->fc_protocol, cfg->fc_scope,
 376                                  (__force u32)cfg->fc_prefsrc,
 377                                  cfg->fc_priority);
 378         hash = fib_info_hashfn_result(hash);
 379         head = &fib_info_hash[hash];
 380
 381         hlist_for_each_entry(fi, head, fib_hash) {
 382                 if (!net_eq(fi->fib_net, net))
 383                         continue;
 384                 if (!fi->nh || fi->nh->id != cfg->fc_nh_id)
 385                         continue;
 386                 if (cfg->fc_protocol == fi->fib_protocol &&
 387                     cfg->fc_scope == fi->fib_scope &&
 388                     cfg->fc_prefsrc == fi->fib_prefsrc &&
 389                     cfg->fc_priority == fi->fib_priority &&
 390                     cfg->fc_type == fi->fib_type &&
 391                     cfg->fc_table == fi->fib_tb_id &&
 392                     !((cfg->fc_flags ^ fi->fib_flags) & ~RTNH_COMPARE_MASK))
 393                         return fi;
 394         }
 395
 396         return NULL;
 397 }
 398
 399 static struct fib_info *fib_find_info(struct fib_info *nfi)
 400 {
 401         struct hlist_head *head;
 402         struct fib_info *fi;
 403         unsigned int hash;
 404
 405         hash = fib_info_hashfn(nfi);
 406         head = &fib_info_hash[hash];
 407
 408         hlist_for_each_entry(fi, head, fib_hash) {
 409                 if (!net_eq(fi->fib_net, nfi->fib_net))
 410                         continue;
 411                 if (fi->fib_nhs != nfi->fib_nhs)
 412                         continue;
 413                 if (nfi->fib_protocol == fi->fib_protocol &&
 414                     nfi->fib_scope == fi->fib_scope &&
 415                     nfi->fib_prefsrc == fi->fib_prefsrc &&
 416                     nfi->fib_priority == fi->fib_priority &&
 417                     nfi->fib_type == fi->fib_type &&
 418                     memcmp(nfi->fib_metrics, fi->fib_metrics,
 419                            sizeof(u32) * RTAX_MAX) == 0 &&
 420                     !((nfi->fib_flags ^ fi->fib_flags) & ~RTNH_COMPARE_MASK) &&
 421                     nh_comp(fi, nfi) == 0)
 422                         return fi;
 423         }
 424
 425         return NULL;
 426 }
 427
 428 /* Check, that the gateway is already configured.
 429  * Used only by redirect accept routine.
 430  */
 431 int ip_fib_check_default(__be32 gw, struct net_device *dev)
 432 {
 433         struct hlist_head *head;
 434         struct fib_nh *nh;
 435         unsigned int hash;
 436
 437         spin_lock(&fib_info_lock);
 438
 439         hash = fib_devindex_hashfn(dev->ifindex);
 440         head = &fib_info_devhash[hash];
 441         hlist_for_each_entry(nh, head, nh_hash) {
 442                 if (nh->fib_nh_dev == dev &&
 443                     nh->fib_nh_gw4 == gw &&
 444                     !(nh->fib_nh_flags & RTNH_F_DEAD)) {
 445                         spin_unlock(&fib_info_lock);
 446                         return 0;
 447                 }
 448         }
 449
 450         spin_unlock(&fib_info_lock);
 451
 452         return -1;
 453 }
 454
 455 static inline size_t fib_nlmsg_size(struct fib_info *fi)
 456 {
 457         size_t payload = NLMSG_ALIGN(sizeof(struct rtmsg))
 458                          + nla_total_size(4) /* RTA_TABLE */
 459                          + nla_total_size(4) /* RTA_DST */
 460                          + nla_total_size(4) /* RTA_PRIORITY */
 461                          + nla_total_size(4) /* RTA_PREFSRC */
 462                          + nla_total_size(TCP_CA_NAME_MAX); /* RTAX_CC_ALGO */
 463         unsigned int nhs = fib_info_num_path(fi);
 464
 465         /* space for nested metrics */
 466         payload += nla_total_size((RTAX_MAX * nla_total_size(4)));
 467
 468         if (fi->nh)
 469                 payload += nla_total_size(4); /* RTA_NH_ID */
 470
 471         if (nhs) {
 472                 size_t nh_encapsize = 0;
 473                 /* Also handles the special case nhs == 1 */
 474
 475                 /* each nexthop is packed in an attribute */
 476                 size_t nhsize = nla_total_size(sizeof(struct rtnexthop));
 477                 unsigned int i;
 478
 479                 /* may contain flow and gateway attribute */
 480                 nhsize += 2 * nla_total_size(4);
 481
 482                 /* grab encap info */
 483                 for (i = 0; i < fib_info_num_path(fi); i++) {
 484                         struct fib_nh_common *nhc = fib_info_nhc(fi, i);
 485
 486                         if (nhc->nhc_lwtstate) {
 487                                 /* RTA_ENCAP_TYPE */
 488                                 nh_encapsize += lwtunnel_get_encap_size(
 489                                                 nhc->nhc_lwtstate);
 490                                 /* RTA_ENCAP */
 491                                 nh_encapsize +=  nla_total_size(2);
 492                         }
 493                 }
 494
 495                 /* all nexthops are packed in a nested attribute */
 496                 payload += nla_total_size((nhs * nhsize) + nh_encapsize);
 497
 498         }
 499
 500         return payload;
 501 }
 502
 503 void rtmsg_fib(int event, __be32 key, struct fib_alias *fa,
 504                int dst_len, u32 tb_id, const struct nl_info *info,
 505                unsigned int nlm_flags)
 506 {
 507         struct fib_rt_info fri;
 508         struct sk_buff *skb;
 509         u32 seq = info->nlh ? info->nlh->nlmsg_seq : 0;
 510         int err = -ENOBUFS;
 511
 512         skb = nlmsg_new(fib_nlmsg_size(fa->fa_info), GFP_KERNEL);
 513         if (!skb)
 514                 goto errout;
 515
 516         fri.fi = fa->fa_info;
 517         fri.tb_id = tb_id;
 518         fri.dst = key;
 519         fri.dst_len = dst_len;
 520         fri.tos = fa->fa_tos;
 521         fri.type = fa->fa_type;
 522         fri.offload = fa->offload;
 523         fri.trap = fa->trap;
 524         err = fib_dump_info(skb, info->portid, seq, event, &fri, nlm_flags);
 525         if (err < 0) {
 526                 /* -EMSGSIZE implies BUG in fib_nlmsg_size() */
 527                 WARN_ON(err == -EMSGSIZE);
 528                 kfree_skb(skb);
 529                 goto errout;
 530         }
 531         rtnl_notify(skb, info->nl_net, info->portid, RTNLGRP_IPV4_ROUTE,
 532                     info->nlh, GFP_KERNEL);
 533         return;
 534 errout:
 535         if (err < 0)
 536                 rtnl_set_sk_err(info->nl_net, RTNLGRP_IPV4_ROUTE, err);
 537 }
 538
 539 static int fib_detect_death(struct fib_info *fi, int order,
 540                             struct fib_info **last_resort, int *last_idx,
 541                             int dflt)
 542 {
 543         const struct fib_nh_common *nhc = fib_info_nhc(fi, 0);
 544         struct neighbour *n;
 545         int state = NUD_NONE;
 546
 547         if (likely(nhc->nhc_gw_family == AF_INET))
 548                 n = neigh_lookup(&arp_tbl, &nhc->nhc_gw.ipv4, nhc->nhc_dev);
 549         else if (nhc->nhc_gw_family == AF_INET6)
 550                 n = neigh_lookup(ipv6_stub->nd_tbl, &nhc->nhc_gw.ipv6,
 551                                  nhc->nhc_dev);
 552         else
 553                 n = NULL;
 554
 555         if (n) {
 556                 state = n->nud_state;
 557                 neigh_release(n);
 558         } else {
 559                 return 0;
 560         }
 561         if (state == NUD_REACHABLE)
 562                 return 0;
 563         if ((state & NUD_VALID) && order != dflt)
 564                 return 0;
 565         if ((state & NUD_VALID) ||
 566             (*last_idx < 0 && order > dflt && state != NUD_INCOMPLETE)) {
 567                 *last_resort = fi;
 568                 *last_idx = order;
 569         }
 570         return 1;
 571 }
 572
 573 int fib_nh_common_init(struct fib_nh_common *nhc, struct nlattr *encap,
 574                        u16 encap_type, void *cfg, gfp_t gfp_flags,
 575                        struct netlink_ext_ack *extack)
 576 {
 577         int err;
 578
 579         nhc->nhc_pcpu_rth_output = alloc_percpu_gfp(struct rtable __rcu *,
 580                                                     gfp_flags);
 581         if (!nhc->nhc_pcpu_rth_output)
 582                 return -ENOMEM;
 583
 584         if (encap) {
 585                 struct lwtunnel_state *lwtstate;
 586
 587                 if (encap_type == LWTUNNEL_ENCAP_NONE) {
 588                         NL_SET_ERR_MSG(extack, "LWT encap type not specified");
 589                         err = -EINVAL;
 590                         goto lwt_failure;
 591                 }
 592                 err = lwtunnel_build_state(encap_type, encap, nhc->nhc_family,
 593                                            cfg, &lwtstate, extack);
 594                 if (err)
 595                         goto lwt_failure;
 596
 597                 nhc->nhc_lwtstate = lwtstate_get(lwtstate);
 598         }
 599
 600         return 0;
 601
 602 lwt_failure:
 603         rt_fibinfo_free_cpus(nhc->nhc_pcpu_rth_output);
 604         nhc->nhc_pcpu_rth_output = NULL;
 605         return err;
 606 }
 607 EXPORT_SYMBOL_GPL(fib_nh_common_init);
 608
 609 int fib_nh_init(struct net *net, struct fib_nh *nh,
 610                 struct fib_config *cfg, int nh_weight,
 611                 struct netlink_ext_ack *extack)
 612 {
 613         int err;
 614
 615         nh->fib_nh_family = AF_INET;
 616
 617         err = fib_nh_common_init(&nh->nh_common, cfg->fc_encap,
 618                                  cfg->fc_encap_type, cfg, GFP_KERNEL, extack);
 619         if (err)
 620                 return err;
 621
 622         nh->fib_nh_oif = cfg->fc_oif;
 623         nh->fib_nh_gw_family = cfg->fc_gw_family;
 624         if (cfg->fc_gw_family == AF_INET)
 625                 nh->fib_nh_gw4 = cfg->fc_gw4;
 626         else if (cfg->fc_gw_family == AF_INET6)
 627                 nh->fib_nh_gw6 = cfg->fc_gw6;
 628
 629         nh->fib_nh_flags = cfg->fc_flags;
 630
 631 #ifdef CONFIG_IP_ROUTE_CLASSID
 632         nh->nh_tclassid = cfg->fc_flow;
 633         if (nh->nh_tclassid)
 634                 net->ipv4.fib_num_tclassid_users++;
 635 #endif
 636 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 637         nh->fib_nh_weight = nh_weight;
 638 #endif
 639         return 0;
 640 }
 641
 642 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 643
 644 static int fib_count_nexthops(struct rtnexthop *rtnh, int remaining,
 645                               struct netlink_ext_ack *extack)
 646 {
 647         int nhs = 0;
 648
 649         while (rtnh_ok(rtnh, remaining)) {
 650                 nhs++;
 651                 rtnh = rtnh_next(rtnh, &remaining);
 652         }
 653
 654         /* leftover implies invalid nexthop configuration, discard it */
 655         if (remaining > 0) {
 656                 NL_SET_ERR_MSG(extack,
 657                                "Invalid nexthop configuration - extra data after nexthops");
 658                 nhs = 0;
 659         }
 660
 661         return nhs;
 662 }
 663
 664 /* only called when fib_nh is integrated into fib_info */
 665 static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh,
 666                        int remaining, struct fib_config *cfg,
 667                        struct netlink_ext_ack *extack)
 668 {
 669         struct net *net = fi->fib_net;
 670         struct fib_config fib_cfg;
 671         struct fib_nh *nh;
 672         int ret;
 673
 674         change_nexthops(fi) {
 675                 int attrlen;
 676
 677                 memset(&fib_cfg, 0, sizeof(fib_cfg));
 678
 679                 if (!rtnh_ok(rtnh, remaining)) {
 680                         NL_SET_ERR_MSG(extack,
 681                                        "Invalid nexthop configuration - extra data after nexthop");
 682                         return -EINVAL;
 683                 }
 684
 685                 if (rtnh->rtnh_flags & (RTNH_F_DEAD | RTNH_F_LINKDOWN)) {
 686                         NL_SET_ERR_MSG(extack,
 687                                        "Invalid flags for nexthop - can not contain DEAD or LINKDOWN");
 688                         return -EINVAL;
 689                 }
 690
 691                 fib_cfg.fc_flags = (cfg->fc_flags & ~0xFF) | rtnh->rtnh_flags;
 692                 fib_cfg.fc_oif = rtnh->rtnh_ifindex;
 693
 694                 attrlen = rtnh_attrlen(rtnh);
 695                 if (attrlen > 0) {
 696                         struct nlattr *nla, *nlav, *attrs = rtnh_attrs(rtnh);
 697
 698                         nla = nla_find(attrs, attrlen, RTA_GATEWAY);
 699                         nlav = nla_find(attrs, attrlen, RTA_VIA);
 700                         if (nla && nlav) {
 701                                 NL_SET_ERR_MSG(extack,
 702                                                "Nexthop configuration can not contain both GATEWAY and VIA");
 703                                 return -EINVAL;
 704                         }
 705                         if (nla) {
 706                                 fib_cfg.fc_gw4 = nla_get_in_addr(nla);
 707                                 if (fib_cfg.fc_gw4)
 708                                         fib_cfg.fc_gw_family = AF_INET;
 709                         } else if (nlav) {
 710                                 ret = fib_gw_from_via(&fib_cfg, nlav, extack);
 711                                 if (ret)
 712                                         goto errout;
 713                         }
 714
 715                         nla = nla_find(attrs, attrlen, RTA_FLOW);
 716                         if (nla)
 717                                 fib_cfg.fc_flow = nla_get_u32(nla);
 718
 719                         fib_cfg.fc_encap = nla_find(attrs, attrlen, RTA_ENCAP);
 720                         nla = nla_find(attrs, attrlen, RTA_ENCAP_TYPE);
 721                         if (nla)
 722                                 fib_cfg.fc_encap_type = nla_get_u16(nla);
 723                 }
 724
 725                 ret = fib_nh_init(net, nexthop_nh, &fib_cfg,
 726                                   rtnh->rtnh_hops + 1, extack);
 727                 if (ret)
 728                         goto errout;
 729
 730                 rtnh = rtnh_next(rtnh, &remaining);
 731         } endfor_nexthops(fi);
 732
 733         ret = -EINVAL;
 734         nh = fib_info_nh(fi, 0);
 735         if (cfg->fc_oif && nh->fib_nh_oif != cfg->fc_oif) {
 736                 NL_SET_ERR_MSG(extack,
 737                                "Nexthop device index does not match RTA_OIF");
 738                 goto errout;
 739         }
 740         if (cfg->fc_gw_family) {
 741                 if (cfg->fc_gw_family != nh->fib_nh_gw_family ||
 742                     (cfg->fc_gw_family == AF_INET &&
 743                      nh->fib_nh_gw4 != cfg->fc_gw4) ||
 744                     (cfg->fc_gw_family == AF_INET6 &&
 745                      ipv6_addr_cmp(&nh->fib_nh_gw6, &cfg->fc_gw6))) {
 746                         NL_SET_ERR_MSG(extack,
 747                                        "Nexthop gateway does not match RTA_GATEWAY or RTA_VIA");
 748                         goto errout;
 749                 }
 750         }
 751 #ifdef CONFIG_IP_ROUTE_CLASSID
 752         if (cfg->fc_flow && nh->nh_tclassid != cfg->fc_flow) {
 753                 NL_SET_ERR_MSG(extack,
 754                                "Nexthop class id does not match RTA_FLOW");
 755                 goto errout;
 756         }
 757 #endif
 758         ret = 0;
 759 errout:
 760         return ret;
 761 }
 762
 763 /* only called when fib_nh is integrated into fib_info */
 764 static void fib_rebalance(struct fib_info *fi)
 765 {
 766         int total;
 767         int w;
 768
 769         if (fib_info_num_path(fi) < 2)
 770                 return;
 771
 772         total = 0;
 773         for_nexthops(fi) {
 774                 if (nh->fib_nh_flags & RTNH_F_DEAD)
 775                         continue;
 776
 777                 if (ip_ignore_linkdown(nh->fib_nh_dev) &&
 778                     nh->fib_nh_flags & RTNH_F_LINKDOWN)
 779                         continue;
 780
 781                 total += nh->fib_nh_weight;
 782         } endfor_nexthops(fi);
 783
 784         w = 0;
 785         change_nexthops(fi) {
 786                 int upper_bound;
 787
 788                 if (nexthop_nh->fib_nh_flags & RTNH_F_DEAD) {
 789                         upper_bound = -1;
 790                 } else if (ip_ignore_linkdown(nexthop_nh->fib_nh_dev) &&
 791                            nexthop_nh->fib_nh_flags & RTNH_F_LINKDOWN) {
 792                         upper_bound = -1;
 793                 } else {
 794                         w += nexthop_nh->fib_nh_weight;
 795                         upper_bound = DIV_ROUND_CLOSEST_ULL((u64)w << 31,
 796                                                             total) - 1;
 797                 }
 798
 799                 atomic_set(&nexthop_nh->fib_nh_upper_bound, upper_bound);
 800         } endfor_nexthops(fi);
 801 }
 802 #else /* CONFIG_IP_ROUTE_MULTIPATH */
 803
 804 static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh,
 805                        int remaining, struct fib_config *cfg,
 806                        struct netlink_ext_ack *extack)
 807 {
 808         NL_SET_ERR_MSG(extack, "Multipath support not enabled in kernel");
 809
 810         return -EINVAL;
 811 }
 812
 813 #define fib_rebalance(fi) do { } while (0)
 814
 815 #endif /* CONFIG_IP_ROUTE_MULTIPATH */
 816
 817 static int fib_encap_match(u16 encap_type,
 818                            struct nlattr *encap,
 819                            const struct fib_nh *nh,
 820                            const struct fib_config *cfg,
 821                            struct netlink_ext_ack *extack)
 822 {
 823         struct lwtunnel_state *lwtstate;
 824         int ret, result = 0;
 825
 826         if (encap_type == LWTUNNEL_ENCAP_NONE)
 827                 return 0;
 828
 829         ret = lwtunnel_build_state(encap_type, encap, AF_INET,
 830                                    cfg, &lwtstate, extack);
 831         if (!ret) {
 832                 result = lwtunnel_cmp_encap(lwtstate, nh->fib_nh_lws);
 833                 lwtstate_free(lwtstate);
 834         }
 835
 836         return result;
 837 }
 838
 839 int fib_nh_match(struct fib_config *cfg, struct fib_info *fi,
 840                  struct netlink_ext_ack *extack)
 841 {
 842 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 843         struct rtnexthop *rtnh;
 844         int remaining;
 845 #endif
 846
 847         if (cfg->fc_priority && cfg->fc_priority != fi->fib_priority)
 848                 return 1;
 849
 850         if (cfg->fc_nh_id) {
 851                 if (fi->nh && cfg->fc_nh_id == fi->nh->id)
 852                         return 0;
 853                 return 1;
 854         }
 855
 856         if (cfg->fc_oif || cfg->fc_gw_family) {
 857                 struct fib_nh *nh = fib_info_nh(fi, 0);
 858
 859                 if (cfg->fc_encap) {
 860                         if (fib_encap_match(cfg->fc_encap_type, cfg->fc_encap,
 861                                             nh, cfg, extack))
 862                                 return 1;
 863                 }
 864 #ifdef CONFIG_IP_ROUTE_CLASSID
 865                 if (cfg->fc_flow &&
 866                     cfg->fc_flow != nh->nh_tclassid)
 867                         return 1;
 868 #endif
 869                 if ((cfg->fc_oif && cfg->fc_oif != nh->fib_nh_oif) ||
 870                     (cfg->fc_gw_family &&
 871                      cfg->fc_gw_family != nh->fib_nh_gw_family))
 872                         return 1;
 873
 874                 if (cfg->fc_gw_family == AF_INET &&
 875                     cfg->fc_gw4 != nh->fib_nh_gw4)
 876                         return 1;
 877
 878                 if (cfg->fc_gw_family == AF_INET6 &&
 879                     ipv6_addr_cmp(&cfg->fc_gw6, &nh->fib_nh_gw6))
 880                         return 1;
 881
 882                 return 0;
 883         }
 884
 885 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 886         if (!cfg->fc_mp)
 887                 return 0;
 888
 889         rtnh = cfg->fc_mp;
 890         remaining = cfg->fc_mp_len;
 891
 892         for_nexthops(fi) {
 893                 int attrlen;
 894
 895                 if (!rtnh_ok(rtnh, remaining))
 896                         return -EINVAL;
 897
 898                 if (rtnh->rtnh_ifindex && rtnh->rtnh_ifindex != nh->fib_nh_oif)
 899                         return 1;
 900
 901                 attrlen = rtnh_attrlen(rtnh);
 902                 if (attrlen > 0) {
 903                         struct nlattr *nla, *nlav, *attrs = rtnh_attrs(rtnh);
 904
 905                         nla = nla_find(attrs, attrlen, RTA_GATEWAY);
 906                         nlav = nla_find(attrs, attrlen, RTA_VIA);
 907                         if (nla && nlav) {
 908                                 NL_SET_ERR_MSG(extack,
 909                                                "Nexthop configuration can not contain both GATEWAY and VIA");
 910                                 return -EINVAL;
 911                         }
 912
 913                         if (nla) {
 914                                 if (nh->fib_nh_gw_family != AF_INET ||
 915                                     nla_get_in_addr(nla) != nh->fib_nh_gw4)
 916                                         return 1;
 917                         } else if (nlav) {
 918                                 struct fib_config cfg2;
 919                                 int err;
 920
 921                                 err = fib_gw_from_via(&cfg2, nlav, extack);
 922                                 if (err)
 923                                         return err;
 924
 925                                 switch (nh->fib_nh_gw_family) {
 926                                 case AF_INET:
 927                                         if (cfg2.fc_gw_family != AF_INET ||
 928                                             cfg2.fc_gw4 != nh->fib_nh_gw4)
 929                                                 return 1;
 930                                         break;
 931                                 case AF_INET6:
 932                                         if (cfg2.fc_gw_family != AF_INET6 ||
 933                                             ipv6_addr_cmp(&cfg2.fc_gw6,
 934                                                           &nh->fib_nh_gw6))
 935                                                 return 1;
 936                                         break;
 937                                 }
 938                         }
 939
 940 #ifdef CONFIG_IP_ROUTE_CLASSID
 941                         nla = nla_find(attrs, attrlen, RTA_FLOW);
 942                         if (nla && nla_get_u32(nla) != nh->nh_tclassid)
 943                                 return 1;
 944 #endif
 945                 }
 946
 947                 rtnh = rtnh_next(rtnh, &remaining);
 948         } endfor_nexthops(fi);
 949 #endif
 950         return 0;
 951 }
 952
 953 bool fib_metrics_match(struct fib_config *cfg, struct fib_info *fi)
 954 {
 955         struct nlattr *nla;
 956         int remaining;
 957
 958         if (!cfg->fc_mx)
 959                 return true;
 960
 961         nla_for_each_attr(nla, cfg->fc_mx, cfg->fc_mx_len, remaining) {
 962                 int type = nla_type(nla);
 963                 u32 fi_val, val;
 964
 965                 if (!type)
 966                         continue;
 967                 if (type > RTAX_MAX)
 968                         return false;
 969
 970                 if (type == RTAX_CC_ALGO) {
 971                         char tmp[TCP_CA_NAME_MAX];
 972                         bool ecn_ca = false;
 973
 974                         nla_strlcpy(tmp, nla, sizeof(tmp));
 975                         val = tcp_ca_get_key_by_name(fi->fib_net, tmp, &ecn_ca);
 976                 } else {
 977                         if (nla_len(nla) != sizeof(u32))
 978                                 return false;
 979                         val = nla_get_u32(nla);
 980                 }
 981
 982                 fi_val = fi->fib_metrics->metrics[type - 1];
 983                 if (type == RTAX_FEATURES)
 984                         fi_val &= ~DST_FEATURE_ECN_CA;
 985
 986                 if (fi_val != val)
 987                         return false;
 988         }
 989
 990         return true;
 991 }
 992
 993 static int fib_check_nh_v6_gw(struct net *net, struct fib_nh *nh,
 994                               u32 table, struct netlink_ext_ack *extack)
 995 {
 996         struct fib6_config cfg = {
 997                 .fc_table = table,
 998                 .fc_flags = nh->fib_nh_flags | RTF_GATEWAY,
 999                 .fc_ifindex = nh->fib_nh_oif,
1000                 .fc_gateway = nh->fib_nh_gw6,
1001         };
1002         struct fib6_nh fib6_nh = {};
1003         int err;
1004
1005         err = ipv6_stub->fib6_nh_init(net, &fib6_nh, &cfg, GFP_KERNEL, extack);
1006         if (!err) {
1007                 nh->fib_nh_dev = fib6_nh.fib_nh_dev;
1008                 dev_hold(nh->fib_nh_dev);
1009                 nh->fib_nh_oif = nh->fib_nh_dev->ifindex;
1010                 nh->fib_nh_scope = RT_SCOPE_LINK;
1011
1012                 ipv6_stub->fib6_nh_release(&fib6_nh);
1013         }
1014
1015         return err;
1016 }
1017
1018 /*
1019  * Picture
1020  * -------
1021  *
1022  * Semantics of nexthop is very messy by historical reasons.
1023  * We have to take into account, that:
1024  * a) gateway can be actually local interface address,
1025  *    so that gatewayed route is direct.
1026  * b) gateway must be on-link address, possibly
1027  *    described not by an ifaddr, but also by a direct route.
1028  * c) If both gateway and interface are specified, they should not
1029  *    contradict.
1030  * d) If we use tunnel routes, gateway could be not on-link.
1031  *
1032  * Attempt to reconcile all of these (alas, self-contradictory) conditions
1033  * results in pretty ugly and hairy code with obscure logic.
1034  *
1035  * I chose to generalized it instead, so that the size
1036  * of code does not increase practically, but it becomes
1037  * much more general.
1038  * Every prefix is assigned a "scope" value: "host" is local address,
1039  * "link" is direct route,
1040  * [ ... "site" ... "interior" ... ]
1041  * and "universe" is true gateway route with global meaning.
1042  *
1043  * Every prefix refers to a set of "nexthop"s (gw, oif),
1044  * where gw must have narrower scope. This recursion stops
1045  * when gw has LOCAL scope or if "nexthop" is declared ONLINK,
1046  * which means that gw is forced to be on link.
1047  *
1048  * Code is still hairy, but now it is apparently logically
1049  * consistent and very flexible. F.e. as by-product it allows
1050  * to co-exists in peace independent exterior and interior
1051  * routing processes.
1052  *
1053  * Normally it looks as following.
1054  *
1055  * {universe prefix}  -> (gw, oif) [scope link]
1056  *                |
1057  *                |-> {link prefix} -> (gw, oif) [scope local]
1058  *                                      |
1059  *                                      |-> {local prefix} (terminal node)
1060  */
1061 static int fib_check_nh_v4_gw(struct net *net, struct fib_nh *nh, u32 table,
1062                               u8 scope, struct netlink_ext_ack *extack)
1063 {
1064         struct net_device *dev;
1065         struct fib_result res;
1066         int err = 0;
1067
1068         if (nh->fib_nh_flags & RTNH_F_ONLINK) {
1069                 unsigned int addr_type;
1070
1071                 if (scope >= RT_SCOPE_LINK) {
1072                         NL_SET_ERR_MSG(extack, "Nexthop has invalid scope");
1073                         return -EINVAL;
1074                 }
1075                 dev = __dev_get_by_index(net, nh->fib_nh_oif);
1076                 if (!dev) {
1077                         NL_SET_ERR_MSG(extack, "Nexthop device required for onlink");
1078                         return -ENODEV;
1079                 }
1080                 if (!(dev->flags & IFF_UP)) {
1081                         NL_SET_ERR_MSG(extack, "Nexthop device is not up");
1082                         return -ENETDOWN;
1083                 }
1084                 addr_type = inet_addr_type_dev_table(net, dev, nh->fib_nh_gw4);
1085                 if (addr_type != RTN_UNICAST) {
1086                         NL_SET_ERR_MSG(extack, "Nexthop has invalid gateway");
1087                         return -EINVAL;
1088                 }
1089                 if (!netif_carrier_ok(dev))
1090                         nh->fib_nh_flags |= RTNH_F_LINKDOWN;
1091                 nh->fib_nh_dev = dev;
1092                 dev_hold(dev);
1093                 nh->fib_nh_scope = RT_SCOPE_LINK;
1094                 return 0;
1095         }
1096         rcu_read_lock();
1097         {
1098                 struct fib_table *tbl = NULL;
1099                 struct flowi4 fl4 = {
1100                         .daddr = nh->fib_nh_gw4,
1101                         .flowi4_scope = scope + 1,
1102                         .flowi4_oif = nh->fib_nh_oif,
1103                         .flowi4_iif = LOOPBACK_IFINDEX,
1104                 };
1105
1106                 /* It is not necessary, but requires a bit of thinking */
1107                 if (fl4.flowi4_scope < RT_SCOPE_LINK)
1108                         fl4.flowi4_scope = RT_SCOPE_LINK;
1109
1110                 if (table)
1111                         tbl = fib_get_table(net, table);
1112
1113                 if (tbl)
1114                         err = fib_table_lookup(tbl, &fl4, &res,
1115                                                FIB_LOOKUP_IGNORE_LINKSTATE |
1116                                                FIB_LOOKUP_NOREF);
1117
1118                 /* on error or if no table given do full lookup. This
1119                  * is needed for example when nexthops are in the local
1120                  * table rather than the given table
1121                  */
1122                 if (!tbl || err) {
1123                         err = fib_lookup(net, &fl4, &res,
1124                                          FIB_LOOKUP_IGNORE_LINKSTATE);
1125                 }
1126
1127                 if (err) {
1128                         NL_SET_ERR_MSG(extack, "Nexthop has invalid gateway");
1129                         goto out;
1130                 }
1131         }
1132
1133         err = -EINVAL;
1134         if (res.type != RTN_UNICAST && res.type != RTN_LOCAL) {
1135                 NL_SET_ERR_MSG(extack, "Nexthop has invalid gateway");
1136                 goto out;
1137         }
1138         nh->fib_nh_scope = res.scope;
1139         nh->fib_nh_oif = FIB_RES_OIF(res);
1140         nh->fib_nh_dev = dev = FIB_RES_DEV(res);
1141         if (!dev) {
1142                 NL_SET_ERR_MSG(extack,
1143                                "No egress device for nexthop gateway");
1144                 goto out;
1145         }
1146         dev_hold(dev);
1147         if (!netif_carrier_ok(dev))
1148                 nh->fib_nh_flags |= RTNH_F_LINKDOWN;
1149         err = (dev->flags & IFF_UP) ? 0 : -ENETDOWN;
1150 out:
1151         rcu_read_unlock();
1152         return err;
1153 }
1154
1155 static int fib_check_nh_nongw(struct net *net, struct fib_nh *nh,
1156                               struct netlink_ext_ack *extack)
1157 {
1158         struct in_device *in_dev;
1159         int err;
1160
1161         if (nh->fib_nh_flags & (RTNH_F_PERVASIVE | RTNH_F_ONLINK)) {
1162                 NL_SET_ERR_MSG(extack,
1163                                "Invalid flags for nexthop - PERVASIVE and ONLINK can not be set");
1164                 return -EINVAL;
1165         }
1166
1167         rcu_read_lock();
1168
1169         err = -ENODEV;
1170         in_dev = inetdev_by_index(net, nh->fib_nh_oif);
1171         if (!in_dev)
1172                 goto out;
1173         err = -ENETDOWN;
1174         if (!(in_dev->dev->flags & IFF_UP)) {
1175                 NL_SET_ERR_MSG(extack, "Device for nexthop is not up");
1176                 goto out;
1177         }
1178
1179         nh->fib_nh_dev = in_dev->dev;
1180         dev_hold(nh->fib_nh_dev);
1181         nh->fib_nh_scope = RT_SCOPE_HOST;
1182         if (!netif_carrier_ok(nh->fib_nh_dev))
1183                 nh->fib_nh_flags |= RTNH_F_LINKDOWN;
1184         err = 0;
1185 out:
1186         rcu_read_unlock();
1187         return err;
1188 }
1189
1190 int fib_check_nh(struct net *net, struct fib_nh *nh, u32 table, u8 scope,
1191                  struct netlink_ext_ack *extack)
1192 {
1193         int err;
1194
1195         if (nh->fib_nh_gw_family == AF_INET)
1196                 err = fib_check_nh_v4_gw(net, nh, table, scope, extack);
1197         else if (nh->fib_nh_gw_family == AF_INET6)
1198                 err = fib_check_nh_v6_gw(net, nh, table, extack);
1199         else
1200                 err = fib_check_nh_nongw(net, nh, extack);
1201
1202         return err;
1203 }
1204
1205 static inline unsigned int fib_laddr_hashfn(__be32 val)
1206 {
1207         unsigned int mask = (fib_info_hash_size - 1);
1208
1209         return ((__force u32)val ^
1210                 ((__force u32)val >> 7) ^
1211                 ((__force u32)val >> 14)) & mask;
1212 }
1213
1214 static struct hlist_head *fib_info_hash_alloc(int bytes)
1215 {
1216         if (bytes <= PAGE_SIZE)
1217                 return kzalloc(bytes, GFP_KERNEL);
1218         else
1219                 return (struct hlist_head *)
1220                         __get_free_pages(GFP_KERNEL | __GFP_ZERO,
1221                                          get_order(bytes));
1222 }
1223
1224 static void fib_info_hash_free(struct hlist_head *hash, int bytes)
1225 {
1226         if (!hash)
1227                 return;
1228
1229         if (bytes <= PAGE_SIZE)
1230                 kfree(hash);
1231         else
1232                 free_pages((unsigned long) hash, get_order(bytes));
1233 }
1234
1235 static void fib_info_hash_move(struct hlist_head *new_info_hash,
1236                                struct hlist_head *new_laddrhash,
1237                                unsigned int new_size)
1238 {
1239         struct hlist_head *old_info_hash, *old_laddrhash;
1240         unsigned int old_size = fib_info_hash_size;
1241         unsigned int i, bytes;
1242
1243         spin_lock_bh(&fib_info_lock);
1244         old_info_hash = fib_info_hash;
1245         old_laddrhash = fib_info_laddrhash;
1246         fib_info_hash_size = new_size;
1247
1248         for (i = 0; i < old_size; i++) {
1249                 struct hlist_head *head = &fib_info_hash[i];
1250                 struct hlist_node *n;
1251                 struct fib_info *fi;
1252
1253                 hlist_for_each_entry_safe(fi, n, head, fib_hash) {
1254                         struct hlist_head *dest;
1255                         unsigned int new_hash;
1256
1257                         new_hash = fib_info_hashfn(fi);
1258                         dest = &new_info_hash[new_hash];
1259                         hlist_add_head(&fi->fib_hash, dest);
1260                 }
1261         }
1262         fib_info_hash = new_info_hash;
1263
1264         for (i = 0; i < old_size; i++) {
1265                 struct hlist_head *lhead = &fib_info_laddrhash[i];
1266                 struct hlist_node *n;
1267                 struct fib_info *fi;
1268
1269                 hlist_for_each_entry_safe(fi, n, lhead, fib_lhash) {
1270                         struct hlist_head *ldest;
1271                         unsigned int new_hash;
1272
1273                         new_hash = fib_laddr_hashfn(fi->fib_prefsrc);
1274                         ldest = &new_laddrhash[new_hash];
1275                         hlist_add_head(&fi->fib_lhash, ldest);
1276                 }
1277         }
1278         fib_info_laddrhash = new_laddrhash;
1279
1280         spin_unlock_bh(&fib_info_lock);
1281
1282         bytes = old_size * sizeof(struct hlist_head *);
1283         fib_info_hash_free(old_info_hash, bytes);
1284         fib_info_hash_free(old_laddrhash, bytes);
1285 }
1286
1287 __be32 fib_info_update_nhc_saddr(struct net *net, struct fib_nh_common *nhc,
1288                                  unsigned char scope)
1289 {
1290         struct fib_nh *nh;
1291
1292         if (nhc->nhc_family != AF_INET)
1293                 return inet_select_addr(nhc->nhc_dev, 0, scope);
1294
1295         nh = container_of(nhc, struct fib_nh, nh_common);
1296         nh->nh_saddr = inet_select_addr(nh->fib_nh_dev, nh->fib_nh_gw4, scope);
1297         nh->nh_saddr_genid = atomic_read(&net->ipv4.dev_addr_genid);
1298
1299         return nh->nh_saddr;
1300 }
1301
1302 __be32 fib_result_prefsrc(struct net *net, struct fib_result *res)
1303 {
1304         struct fib_nh_common *nhc = res->nhc;
1305
1306         if (res->fi->fib_prefsrc)
1307                 return res->fi->fib_prefsrc;
1308
1309         if (nhc->nhc_family == AF_INET) {
1310                 struct fib_nh *nh;
1311
1312                 nh = container_of(nhc, struct fib_nh, nh_common);
1313                 if (nh->nh_saddr_genid == atomic_read(&net->ipv4.dev_addr_genid))
1314                         return nh->nh_saddr;
1315         }
1316
1317         return fib_info_update_nhc_saddr(net, nhc, res->fi->fib_scope);
1318 }
1319
1320 static bool fib_valid_prefsrc(struct fib_config *cfg, __be32 fib_prefsrc)
1321 {
1322         if (cfg->fc_type != RTN_LOCAL || !cfg->fc_dst ||
1323             fib_prefsrc != cfg->fc_dst) {
1324                 u32 tb_id = cfg->fc_table;
1325                 int rc;
1326
1327                 if (tb_id == RT_TABLE_MAIN)
1328                         tb_id = RT_TABLE_LOCAL;
1329
1330                 rc = inet_addr_type_table(cfg->fc_nlinfo.nl_net,
1331                                           fib_prefsrc, tb_id);
1332
1333                 if (rc != RTN_LOCAL && tb_id != RT_TABLE_LOCAL) {
1334                         rc = inet_addr_type_table(cfg->fc_nlinfo.nl_net,
1335                                                   fib_prefsrc, RT_TABLE_LOCAL);
1336                 }
1337
1338                 if (rc != RTN_LOCAL)
1339                         return false;
1340         }
1341         return true;
1342 }
1343
1344 struct fib_info *fib_create_info(struct fib_config *cfg,
1345                                  struct netlink_ext_ack *extack)
1346 {
1347         int err;
1348         struct fib_info *fi = NULL;
1349         struct nexthop *nh = NULL;
1350         struct fib_info *ofi;
1351         int nhs = 1;
1352         struct net *net = cfg->fc_nlinfo.nl_net;
1353
1354         if (cfg->fc_type > RTN_MAX)
1355                 goto err_inval;
1356
1357         /* Fast check to catch the most weird cases */
1358         if (fib_props[cfg->fc_type].scope > cfg->fc_scope) {
1359                 NL_SET_ERR_MSG(extack, "Invalid scope");
1360                 goto err_inval;
1361         }
1362
1363         if (cfg->fc_flags & (RTNH_F_DEAD | RTNH_F_LINKDOWN)) {
1364                 NL_SET_ERR_MSG(extack,
1365                                "Invalid rtm_flags - can not contain DEAD or LINKDOWN");
1366                 goto err_inval;
1367         }
1368
1369         if (cfg->fc_nh_id) {
1370                 if (!cfg->fc_mx) {
1371                         fi = fib_find_info_nh(net, cfg);
1372                         if (fi) {
1373                                 fi->fib_treeref++;
1374                                 return fi;
1375                         }
1376                 }
1377
1378                 nh = nexthop_find_by_id(net, cfg->fc_nh_id);
1379                 if (!nh) {
1380                         NL_SET_ERR_MSG(extack, "Nexthop id does not exist");
1381                         goto err_inval;
1382                 }
1383                 nhs = 0;
1384         }
1385
1386 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1387         if (cfg->fc_mp) {
1388                 nhs = fib_count_nexthops(cfg->fc_mp, cfg->fc_mp_len, extack);
1389                 if (nhs == 0)
1390                         goto err_inval;
1391         }
1392 #endif
1393
1394         err = -ENOBUFS;
1395         if (fib_info_cnt >= fib_info_hash_size) {
1396                 unsigned int new_size = fib_info_hash_size << 1;
1397                 struct hlist_head *new_info_hash;
1398                 struct hlist_head *new_laddrhash;
1399                 unsigned int bytes;
1400
1401                 if (!new_size)
1402                         new_size = 16;
1403                 bytes = new_size * sizeof(struct hlist_head *);
1404                 new_info_hash = fib_info_hash_alloc(bytes);
1405                 new_laddrhash = fib_info_hash_alloc(bytes);
1406                 if (!new_info_hash || !new_laddrhash) {
1407                         fib_info_hash_free(new_info_hash, bytes);
1408                         fib_info_hash_free(new_laddrhash, bytes);
1409                 } else
1410                         fib_info_hash_move(new_info_hash, new_laddrhash, new_size);
1411
1412                 if (!fib_info_hash_size)
1413                         goto failure;
1414         }
1415
1416         fi = kzalloc(struct_size(fi, fib_nh, nhs), GFP_KERNEL);
1417         if (!fi)
1418                 goto failure;
1419         fi->fib_metrics = ip_fib_metrics_init(fi->fib_net, cfg->fc_mx,
1420                                               cfg->fc_mx_len, extack);
1421         if (IS_ERR(fi->fib_metrics)) {
1422                 err = PTR_ERR(fi->fib_metrics);
1423                 kfree(fi);
1424                 return ERR_PTR(err);
1425         }
1426
1427         fib_info_cnt++;
1428         fi->fib_net = net;
1429         fi->fib_protocol = cfg->fc_protocol;
1430         fi->fib_scope = cfg->fc_scope;
1431         fi->fib_flags = cfg->fc_flags;
1432         fi->fib_priority = cfg->fc_priority;
1433         fi->fib_prefsrc = cfg->fc_prefsrc;
1434         fi->fib_type = cfg->fc_type;
1435         fi->fib_tb_id = cfg->fc_table;
1436
1437         fi->fib_nhs = nhs;
1438         if (nh) {
1439                 if (!nexthop_get(nh)) {
1440                         NL_SET_ERR_MSG(extack, "Nexthop has been deleted");
1441                         err = -EINVAL;
1442                 } else {
1443                         err = 0;
1444                         fi->nh = nh;
1445                 }
1446         } else {
1447                 change_nexthops(fi) {
1448                         nexthop_nh->nh_parent = fi;
1449                 } endfor_nexthops(fi)
1450
1451                 if (cfg->fc_mp)
1452                         err = fib_get_nhs(fi, cfg->fc_mp, cfg->fc_mp_len, cfg,
1453                                           extack);
1454                 else
1455                         err = fib_nh_init(net, fi->fib_nh, cfg, 1, extack);
1456         }
1457
1458         if (err != 0)
1459                 goto failure;
1460
1461         if (fib_props[cfg->fc_type].error) {
1462                 if (cfg->fc_gw_family || cfg->fc_oif || cfg->fc_mp) {
1463                         NL_SET_ERR_MSG(extack,
1464                                        "Gateway, device and multipath can not be specified for this route type");
1465                         goto err_inval;
1466                 }
1467                 goto link_it;
1468         } else {
1469                 switch (cfg->fc_type) {
1470                 case RTN_UNICAST:
1471                 case RTN_LOCAL:
1472                 case RTN_BROADCAST:
1473                 case RTN_ANYCAST:
1474                 case RTN_MULTICAST:
1475                         break;
1476                 default:
1477                         NL_SET_ERR_MSG(extack, "Invalid route type");
1478                         goto err_inval;
1479                 }
1480         }
1481
1482         if (cfg->fc_scope > RT_SCOPE_HOST) {
1483                 NL_SET_ERR_MSG(extack, "Invalid scope");
1484                 goto err_inval;
1485         }
1486
1487         if (fi->nh) {
1488                 err = fib_check_nexthop(fi->nh, cfg->fc_scope, extack);
1489                 if (err)
1490                         goto failure;
1491         } else if (cfg->fc_scope == RT_SCOPE_HOST) {
1492                 struct fib_nh *nh = fi->fib_nh;
1493
1494                 /* Local address is added. */
1495                 if (nhs != 1) {
1496                         NL_SET_ERR_MSG(extack,
1497                                        "Route with host scope can not have multiple nexthops");
1498                         goto err_inval;
1499                 }
1500                 if (nh->fib_nh_gw_family) {
1501                         NL_SET_ERR_MSG(extack,
1502                                        "Route with host scope can not have a gateway");
1503                         goto err_inval;
1504                 }
1505                 nh->fib_nh_scope = RT_SCOPE_NOWHERE;
1506                 nh->fib_nh_dev = dev_get_by_index(net, nh->fib_nh_oif);
1507                 err = -ENODEV;
1508                 if (!nh->fib_nh_dev)
1509                         goto failure;
1510         } else {
1511                 int linkdown = 0;
1512
1513                 change_nexthops(fi) {
1514                         err = fib_check_nh(cfg->fc_nlinfo.nl_net, nexthop_nh,
1515                                            cfg->fc_table, cfg->fc_scope,
1516                                            extack);
1517                         if (err != 0)
1518                                 goto failure;
1519                         if (nexthop_nh->fib_nh_flags & RTNH_F_LINKDOWN)
1520                                 linkdown++;
1521                 } endfor_nexthops(fi)
1522                 if (linkdown == fi->fib_nhs)
1523                         fi->fib_flags |= RTNH_F_LINKDOWN;
1524         }
1525
1526         if (fi->fib_prefsrc && !fib_valid_prefsrc(cfg, fi->fib_prefsrc)) {
1527                 NL_SET_ERR_MSG(extack, "Invalid prefsrc address");
1528                 goto err_inval;
1529         }
1530
1531         if (!fi->nh) {
1532                 change_nexthops(fi) {
1533                         fib_info_update_nhc_saddr(net, &nexthop_nh->nh_common,
1534                                                   fi->fib_scope);
1535                         if (nexthop_nh->fib_nh_gw_family == AF_INET6)
1536                                 fi->fib_nh_is_v6 = true;
1537                 } endfor_nexthops(fi)
1538
1539                 fib_rebalance(fi);
1540         }
1541
1542 link_it:
1543         ofi = fib_find_info(fi);
1544         if (ofi) {
1545                 fi->fib_dead = 1;
1546                 free_fib_info(fi);
1547                 ofi->fib_treeref++;
1548                 return ofi;
1549         }
1550
1551         fi->fib_treeref++;
1552         refcount_set(&fi->fib_clntref, 1);
1553         spin_lock_bh(&fib_info_lock);
1554         hlist_add_head(&fi->fib_hash,
1555                        &fib_info_hash[fib_info_hashfn(fi)]);
1556         if (fi->fib_prefsrc) {
1557                 struct hlist_head *head;
1558
1559                 head = &fib_info_laddrhash[fib_laddr_hashfn(fi->fib_prefsrc)];
1560                 hlist_add_head(&fi->fib_lhash, head);
1561         }
1562         if (fi->nh) {
1563                 list_add(&fi->nh_list, &nh->fi_list);
1564         } else {
1565                 change_nexthops(fi) {
1566                         struct hlist_head *head;
1567                         unsigned int hash;
1568
1569                         if (!nexthop_nh->fib_nh_dev)
1570                                 continue;
1571                         hash = fib_devindex_hashfn(nexthop_nh->fib_nh_dev->ifindex);
1572                         head = &fib_info_devhash[hash];
1573                         hlist_add_head(&nexthop_nh->nh_hash, head);
1574                 } endfor_nexthops(fi)
1575         }
1576         spin_unlock_bh(&fib_info_lock);
1577         return fi;
1578
1579 err_inval:
1580         err = -EINVAL;
1581
1582 failure:
1583         if (fi) {
1584                 fi->fib_dead = 1;
1585                 free_fib_info(fi);
1586         }
1587
1588         return ERR_PTR(err);
1589 }
1590
1591 int fib_nexthop_info(struct sk_buff *skb, const struct fib_nh_common *nhc,
1592                      u8 rt_family, unsigned char *flags, bool skip_oif)
1593 {
1594         if (nhc->nhc_flags & RTNH_F_DEAD)
1595                 *flags |= RTNH_F_DEAD;
1596
1597         if (nhc->nhc_flags & RTNH_F_LINKDOWN) {
1598                 *flags |= RTNH_F_LINKDOWN;
1599
1600                 rcu_read_lock();
1601                 switch (nhc->nhc_family) {
1602                 case AF_INET:
1603                         if (ip_ignore_linkdown(nhc->nhc_dev))
1604                                 *flags |= RTNH_F_DEAD;
1605                         break;
1606                 case AF_INET6:
1607                         if (ip6_ignore_linkdown(nhc->nhc_dev))
1608                                 *flags |= RTNH_F_DEAD;
1609                         break;
1610                 }
1611                 rcu_read_unlock();
1612         }
1613
1614         switch (nhc->nhc_gw_family) {
1615         case AF_INET:
1616                 if (nla_put_in_addr(skb, RTA_GATEWAY, nhc->nhc_gw.ipv4))
1617                         goto nla_put_failure;
1618                 break;
1619         case AF_INET6:
1620                 /* if gateway family does not match nexthop family
1621                  * gateway is encoded as RTA_VIA
1622                  */
1623                 if (rt_family != nhc->nhc_gw_family) {
1624                         int alen = sizeof(struct in6_addr);
1625                         struct nlattr *nla;
1626                         struct rtvia *via;
1627
1628                         nla = nla_reserve(skb, RTA_VIA, alen + 2);
1629                         if (!nla)
1630                                 goto nla_put_failure;
1631
1632                         via = nla_data(nla);
1633                         via->rtvia_family = AF_INET6;
1634                         memcpy(via->rtvia_addr, &nhc->nhc_gw.ipv6, alen);
1635                 } else if (nla_put_in6_addr(skb, RTA_GATEWAY,
1636                                             &nhc->nhc_gw.ipv6) < 0) {
1637                         goto nla_put_failure;
1638                 }
1639                 break;
1640         }
1641
1642         *flags |= (nhc->nhc_flags & RTNH_F_ONLINK);
1643         if (nhc->nhc_flags & RTNH_F_OFFLOAD)
1644                 *flags |= RTNH_F_OFFLOAD;
1645
1646         if (!skip_oif && nhc->nhc_dev &&
1647             nla_put_u32(skb, RTA_OIF, nhc->nhc_dev->ifindex))
1648                 goto nla_put_failure;
1649
1650         if (nhc->nhc_lwtstate &&
1651             lwtunnel_fill_encap(skb, nhc->nhc_lwtstate,
1652                                 RTA_ENCAP, RTA_ENCAP_TYPE) < 0)
1653                 goto nla_put_failure;
1654
1655         return 0;
1656
1657 nla_put_failure:
1658         return -EMSGSIZE;
1659 }
1660 EXPORT_SYMBOL_GPL(fib_nexthop_info);
1661
1662 #if IS_ENABLED(CONFIG_IP_ROUTE_MULTIPATH) || IS_ENABLED(CONFIG_IPV6)
1663 int fib_add_nexthop(struct sk_buff *skb, const struct fib_nh_common *nhc,
1664                     int nh_weight, u8 rt_family)
1665 {
1666         const struct net_device *dev = nhc->nhc_dev;
1667         struct rtnexthop *rtnh;
1668         unsigned char flags = 0;
1669
1670         rtnh = nla_reserve_nohdr(skb, sizeof(*rtnh));
1671         if (!rtnh)
1672                 goto nla_put_failure;
1673
1674         rtnh->rtnh_hops = nh_weight - 1;
1675         rtnh->rtnh_ifindex = dev ? dev->ifindex : 0;
1676
1677         if (fib_nexthop_info(skb, nhc, rt_family, &flags, true) < 0)
1678                 goto nla_put_failure;
1679
1680         rtnh->rtnh_flags = flags;
1681
1682         /* length of rtnetlink header + attributes */
1683         rtnh->rtnh_len = nlmsg_get_pos(skb) - (void *)rtnh;
1684
1685         return 0;
1686
1687 nla_put_failure:
1688         return -EMSGSIZE;
1689 }
1690 EXPORT_SYMBOL_GPL(fib_add_nexthop);
1691 #endif
1692
1693 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1694 static int fib_add_multipath(struct sk_buff *skb, struct fib_info *fi)
1695 {
1696         struct nlattr *mp;
1697
1698         mp = nla_nest_start_noflag(skb, RTA_MULTIPATH);
1699         if (!mp)
1700                 goto nla_put_failure;
1701
1702         if (unlikely(fi->nh)) {
1703                 if (nexthop_mpath_fill_node(skb, fi->nh, AF_INET) < 0)
1704                         goto nla_put_failure;
1705                 goto mp_end;
1706         }
1707
1708         for_nexthops(fi) {
1709                 if (fib_add_nexthop(skb, &nh->nh_common, nh->fib_nh_weight,
1710                                     AF_INET) < 0)
1711                         goto nla_put_failure;
1712 #ifdef CONFIG_IP_ROUTE_CLASSID
1713                 if (nh->nh_tclassid &&
1714                     nla_put_u32(skb, RTA_FLOW, nh->nh_tclassid))
1715                         goto nla_put_failure;
1716 #endif
1717         } endfor_nexthops(fi);
1718
1719 mp_end:
1720         nla_nest_end(skb, mp);
1721
1722         return 0;
1723
1724 nla_put_failure:
1725         return -EMSGSIZE;
1726 }
1727 #else
1728 static int fib_add_multipath(struct sk_buff *skb, struct fib_info *fi)
1729 {
1730         return 0;
1731 }
1732 #endif
1733
1734 int fib_dump_info(struct sk_buff *skb, u32 portid, u32 seq, int event,
1735                   struct fib_rt_info *fri, unsigned int flags)
1736 {
1737         unsigned int nhs = fib_info_num_path(fri->fi);
1738         struct fib_info *fi = fri->fi;
1739         u32 tb_id = fri->tb_id;
1740         struct nlmsghdr *nlh;
1741         struct rtmsg *rtm;
1742
1743         nlh = nlmsg_put(skb, portid, seq, event, sizeof(*rtm), flags);
1744         if (!nlh)
1745                 return -EMSGSIZE;
1746
1747         rtm = nlmsg_data(nlh);
1748         rtm->rtm_family = AF_INET;
1749         rtm->rtm_dst_len = fri->dst_len;
1750         rtm->rtm_src_len = 0;
1751         rtm->rtm_tos = fri->tos;
1752         if (tb_id < 256)
1753                 rtm->rtm_table = tb_id;
1754         else
1755                 rtm->rtm_table = RT_TABLE_COMPAT;
1756         if (nla_put_u32(skb, RTA_TABLE, tb_id))
1757                 goto nla_put_failure;
1758         rtm->rtm_type = fri->type;
1759         rtm->rtm_flags = fi->fib_flags;
1760         rtm->rtm_scope = fi->fib_scope;
1761         rtm->rtm_protocol = fi->fib_protocol;
1762
1763         if (rtm->rtm_dst_len &&
1764             nla_put_in_addr(skb, RTA_DST, fri->dst))
1765                 goto nla_put_failure;
1766         if (fi->fib_priority &&
1767             nla_put_u32(skb, RTA_PRIORITY, fi->fib_priority))
1768                 goto nla_put_failure;
1769         if (rtnetlink_put_metrics(skb, fi->fib_metrics->metrics) < 0)
1770                 goto nla_put_failure;
1771
1772         if (fi->fib_prefsrc &&
1773             nla_put_in_addr(skb, RTA_PREFSRC, fi->fib_prefsrc))
1774                 goto nla_put_failure;
1775
1776         if (fi->nh) {
1777                 if (nla_put_u32(skb, RTA_NH_ID, fi->nh->id))
1778                         goto nla_put_failure;
1779                 if (nexthop_is_blackhole(fi->nh))
1780                         rtm->rtm_type = RTN_BLACKHOLE;
1781         }
1782
1783         if (nhs == 1) {
1784                 const struct fib_nh_common *nhc = fib_info_nhc(fi, 0);
1785                 unsigned char flags = 0;
1786
1787                 if (fib_nexthop_info(skb, nhc, AF_INET, &flags, false) < 0)
1788                         goto nla_put_failure;
1789
1790                 rtm->rtm_flags = flags;
1791 #ifdef CONFIG_IP_ROUTE_CLASSID
1792                 if (nhc->nhc_family == AF_INET) {
1793                         struct fib_nh *nh;
1794
1795                         nh = container_of(nhc, struct fib_nh, nh_common);
1796                         if (nh->nh_tclassid &&
1797                             nla_put_u32(skb, RTA_FLOW, nh->nh_tclassid))
1798                                 goto nla_put_failure;
1799                 }
1800 #endif
1801         } else {
1802                 if (fib_add_multipath(skb, fi) < 0)
1803                         goto nla_put_failure;
1804         }
1805
1806         if (fri->offload)
1807                 rtm->rtm_flags |= RTM_F_OFFLOAD;
1808         if (fri->trap)
1809                 rtm->rtm_flags |= RTM_F_TRAP;
1810
1811         nlmsg_end(skb, nlh);
1812         return 0;
1813
1814 nla_put_failure:
1815         nlmsg_cancel(skb, nlh);
1816         return -EMSGSIZE;
1817 }
1818
1819 /*
1820  * Update FIB if:
1821  * - local address disappeared -> we must delete all the entries
1822  *   referring to it.
1823  * - device went down -> we must shutdown all nexthops going via it.
1824  */
1825 int fib_sync_down_addr(struct net_device *dev, __be32 local)
1826 {
1827         int ret = 0;
1828         unsigned int hash = fib_laddr_hashfn(local);
1829         struct hlist_head *head = &fib_info_laddrhash[hash];
1830         int tb_id = l3mdev_fib_table(dev) ? : RT_TABLE_MAIN;
1831         struct net *net = dev_net(dev);
1832         struct fib_info *fi;
1833
1834         if (!fib_info_laddrhash || local == 0)
1835                 return 0;
1836
1837         hlist_for_each_entry(fi, head, fib_lhash) {
1838                 if (!net_eq(fi->fib_net, net) ||
1839                     fi->fib_tb_id != tb_id)
1840                         continue;
1841                 if (fi->fib_prefsrc == local) {
1842                         fi->fib_flags |= RTNH_F_DEAD;
1843                         ret++;
1844                 }
1845         }
1846         return ret;
1847 }
1848
1849 static int call_fib_nh_notifiers(struct fib_nh *nh,
1850                                  enum fib_event_type event_type)
1851 {
1852         bool ignore_link_down = ip_ignore_linkdown(nh->fib_nh_dev);
1853         struct fib_nh_notifier_info info = {
1854                 .fib_nh = nh,
1855         };
1856
1857         switch (event_type) {
1858         case FIB_EVENT_NH_ADD:
1859                 if (nh->fib_nh_flags & RTNH_F_DEAD)
1860                         break;
1861                 if (ignore_link_down && nh->fib_nh_flags & RTNH_F_LINKDOWN)
1862                         break;
1863                 return call_fib4_notifiers(dev_net(nh->fib_nh_dev), event_type,
1864                                            &info.info);
1865         case FIB_EVENT_NH_DEL:
1866                 if ((ignore_link_down && nh->fib_nh_flags & RTNH_F_LINKDOWN) ||
1867                     (nh->fib_nh_flags & RTNH_F_DEAD))
1868                         return call_fib4_notifiers(dev_net(nh->fib_nh_dev),
1869                                                    event_type, &info.info);
1870         default:
1871                 break;
1872         }
1873
1874         return NOTIFY_DONE;
1875 }
1876
1877 /* Update the PMTU of exceptions when:
1878  * - the new MTU of the first hop becomes smaller than the PMTU
1879  * - the old MTU was the same as the PMTU, and it limited discovery of
1880  *   larger MTUs on the path. With that limit raised, we can now
1881  *   discover larger MTUs
1882  * A special case is locked exceptions, for which the PMTU is smaller
1883  * than the minimal accepted PMTU:
1884  * - if the new MTU is greater than the PMTU, don't make any change
1885  * - otherwise, unlock and set PMTU
1886  */
1887 void fib_nhc_update_mtu(struct fib_nh_common *nhc, u32 new, u32 orig)
1888 {
1889         struct fnhe_hash_bucket *bucket;
1890         int i;
1891
1892         bucket = rcu_dereference_protected(nhc->nhc_exceptions, 1);
1893         if (!bucket)
1894                 return;
1895
1896         for (i = 0; i < FNHE_HASH_SIZE; i++) {
1897                 struct fib_nh_exception *fnhe;
1898
1899                 for (fnhe = rcu_dereference_protected(bucket[i].chain, 1);
1900                      fnhe;
1901                      fnhe = rcu_dereference_protected(fnhe->fnhe_next, 1)) {
1902                         if (fnhe->fnhe_mtu_locked) {
1903                                 if (new <= fnhe->fnhe_pmtu) {
1904                                         fnhe->fnhe_pmtu = new;
1905                                         fnhe->fnhe_mtu_locked = false;
1906                                 }
1907                         } else if (new < fnhe->fnhe_pmtu ||
1908                                    orig == fnhe->fnhe_pmtu) {
1909                                 fnhe->fnhe_pmtu = new;
1910                         }
1911                 }
1912         }
1913 }
1914
1915 void fib_sync_mtu(struct net_device *dev, u32 orig_mtu)
1916 {
1917         unsigned int hash = fib_devindex_hashfn(dev->ifindex);
1918         struct hlist_head *head = &fib_info_devhash[hash];
1919         struct fib_nh *nh;
1920
1921         hlist_for_each_entry(nh, head, nh_hash) {
1922                 if (nh->fib_nh_dev == dev)
1923                         fib_nhc_update_mtu(&nh->nh_common, dev->mtu, orig_mtu);
1924         }
1925 }
1926
1927 /* Event              force Flags           Description
1928  * NETDEV_CHANGE      0     LINKDOWN        Carrier OFF, not for scope host
1929  * NETDEV_DOWN        0     LINKDOWN|DEAD   Link down, not for scope host
1930  * NETDEV_DOWN        1     LINKDOWN|DEAD   Last address removed
1931  * NETDEV_UNREGISTER  1     LINKDOWN|DEAD   Device removed
1932  *
1933  * only used when fib_nh is built into fib_info
1934  */
1935 int fib_sync_down_dev(struct net_device *dev, unsigned long event, bool force)
1936 {
1937         int ret = 0;
1938         int scope = RT_SCOPE_NOWHERE;
1939         struct fib_info *prev_fi = NULL;
1940         unsigned int hash = fib_devindex_hashfn(dev->ifindex);
1941         struct hlist_head *head = &fib_info_devhash[hash];
1942         struct fib_nh *nh;
1943
1944         if (force)
1945                 scope = -1;
1946
1947         hlist_for_each_entry(nh, head, nh_hash) {
1948                 struct fib_info *fi = nh->nh_parent;
1949                 int dead;
1950
1951                 BUG_ON(!fi->fib_nhs);
1952                 if (nh->fib_nh_dev != dev || fi == prev_fi)
1953                         continue;
1954                 prev_fi = fi;
1955                 dead = 0;
1956                 change_nexthops(fi) {
1957                         if (nexthop_nh->fib_nh_flags & RTNH_F_DEAD)
1958                                 dead++;
1959                         else if (nexthop_nh->fib_nh_dev == dev &&
1960                                  nexthop_nh->fib_nh_scope != scope) {
1961                                 switch (event) {
1962                                 case NETDEV_DOWN:
1963                                 case NETDEV_UNREGISTER:
1964                                         nexthop_nh->fib_nh_flags |= RTNH_F_DEAD;
1965                                         /* fall through */
1966                                 case NETDEV_CHANGE:
1967                                         nexthop_nh->fib_nh_flags |= RTNH_F_LINKDOWN;
1968                                         break;
1969                                 }
1970                                 call_fib_nh_notifiers(nexthop_nh,
1971                                                       FIB_EVENT_NH_DEL);
1972                                 dead++;
1973                         }
1974 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1975                         if (event == NETDEV_UNREGISTER &&
1976                             nexthop_nh->fib_nh_dev == dev) {
1977                                 dead = fi->fib_nhs;
1978                                 break;
1979                         }
1980 #endif
1981                 } endfor_nexthops(fi)
1982                 if (dead == fi->fib_nhs) {
1983                         switch (event) {
1984                         case NETDEV_DOWN:
1985                         case NETDEV_UNREGISTER:
1986                                 fi->fib_flags |= RTNH_F_DEAD;
1987                                 /* fall through */
1988                         case NETDEV_CHANGE:
1989                                 fi->fib_flags |= RTNH_F_LINKDOWN;
1990                                 break;
1991                         }
1992                         ret++;
1993                 }
1994
1995                 fib_rebalance(fi);
1996         }
1997
1998         return ret;
1999 }
2000
2001 /* Must be invoked inside of an RCU protected region.  */
2002 static void fib_select_default(const struct flowi4 *flp, struct fib_result *res)
2003 {
2004         struct fib_info *fi = NULL, *last_resort = NULL;
2005         struct hlist_head *fa_head = res->fa_head;
2006         struct fib_table *tb = res->table;
2007         u8 slen = 32 - res->prefixlen;
2008         int order = -1, last_idx = -1;
2009         struct fib_alias *fa, *fa1 = NULL;
2010         u32 last_prio = res->fi->fib_priority;
2011         u8 last_tos = 0;
2012
2013         hlist_for_each_entry_rcu(fa, fa_head, fa_list) {
2014                 struct fib_info *next_fi = fa->fa_info;
2015                 struct fib_nh *nh;
2016
2017                 if (fa->fa_slen != slen)
2018                         continue;
2019                 if (fa->fa_tos && fa->fa_tos != flp->flowi4_tos)
2020                         continue;
2021                 if (fa->tb_id != tb->tb_id)
2022                         continue;
2023                 if (next_fi->fib_priority > last_prio &&
2024                     fa->fa_tos == last_tos) {
2025                         if (last_tos)
2026                                 continue;
2027                         break;
2028                 }
2029                 if (next_fi->fib_flags & RTNH_F_DEAD)
2030                         continue;
2031                 last_tos = fa->fa_tos;
2032                 last_prio = next_fi->fib_priority;
2033
2034                 if (next_fi->fib_scope != res->scope ||
2035                     fa->fa_type != RTN_UNICAST)
2036                         continue;
2037
2038                 nh = fib_info_nh(next_fi, 0);
2039                 if (!nh->fib_nh_gw4 || nh->fib_nh_scope != RT_SCOPE_LINK)
2040                         continue;
2041
2042                 fib_alias_accessed(fa);
2043
2044                 if (!fi) {
2045                         if (next_fi != res->fi)
2046                                 break;
2047                         fa1 = fa;
2048                 } else if (!fib_detect_death(fi, order, &last_resort,
2049                                              &last_idx, fa1->fa_default)) {
2050                         fib_result_assign(res, fi);
2051                         fa1->fa_default = order;
2052                         goto out;
2053                 }
2054                 fi = next_fi;
2055                 order++;
2056         }
2057
2058         if (order <= 0 || !fi) {
2059                 if (fa1)
2060                         fa1->fa_default = -1;
2061                 goto out;
2062         }
2063
2064         if (!fib_detect_death(fi, order, &last_resort, &last_idx,
2065                               fa1->fa_default)) {
2066                 fib_result_assign(res, fi);
2067                 fa1->fa_default = order;
2068                 goto out;
2069         }
2070
2071         if (last_idx >= 0)
2072                 fib_result_assign(res, last_resort);
2073         fa1->fa_default = last_idx;
2074 out:
2075         return;
2076 }
2077
2078 /*
2079  * Dead device goes up. We wake up dead nexthops.
2080  * It takes sense only on multipath routes.
2081  *
2082  * only used when fib_nh is built into fib_info
2083  */
2084 int fib_sync_up(struct net_device *dev, unsigned char nh_flags)
2085 {
2086         struct fib_info *prev_fi;
2087         unsigned int hash;
2088         struct hlist_head *head;
2089         struct fib_nh *nh;
2090         int ret;
2091
2092         if (!(dev->flags & IFF_UP))
2093                 return 0;
2094
2095         if (nh_flags & RTNH_F_DEAD) {
2096                 unsigned int flags = dev_get_flags(dev);
2097
2098                 if (flags & (IFF_RUNNING | IFF_LOWER_UP))
2099                         nh_flags |= RTNH_F_LINKDOWN;
2100         }
2101
2102         prev_fi = NULL;
2103         hash = fib_devindex_hashfn(dev->ifindex);
2104         head = &fib_info_devhash[hash];
2105         ret = 0;
2106
2107         hlist_for_each_entry(nh, head, nh_hash) {
2108                 struct fib_info *fi = nh->nh_parent;
2109                 int alive;
2110
2111                 BUG_ON(!fi->fib_nhs);
2112                 if (nh->fib_nh_dev != dev || fi == prev_fi)
2113                         continue;
2114
2115                 prev_fi = fi;
2116                 alive = 0;
2117                 change_nexthops(fi) {
2118                         if (!(nexthop_nh->fib_nh_flags & nh_flags)) {
2119                                 alive++;
2120                                 continue;
2121                         }
2122                         if (!nexthop_nh->fib_nh_dev ||
2123                             !(nexthop_nh->fib_nh_dev->flags & IFF_UP))
2124                                 continue;
2125                         if (nexthop_nh->fib_nh_dev != dev ||
2126                             !__in_dev_get_rtnl(dev))
2127                                 continue;
2128                         alive++;
2129                         nexthop_nh->fib_nh_flags &= ~nh_flags;
2130                         call_fib_nh_notifiers(nexthop_nh, FIB_EVENT_NH_ADD);
2131                 } endfor_nexthops(fi)
2132
2133                 if (alive > 0) {
2134                         fi->fib_flags &= ~nh_flags;
2135                         ret++;
2136                 }
2137
2138                 fib_rebalance(fi);
2139         }
2140
2141         return ret;
2142 }
2143
2144 #ifdef CONFIG_IP_ROUTE_MULTIPATH
2145 static bool fib_good_nh(const struct fib_nh *nh)
2146 {
2147         int state = NUD_REACHABLE;
2148
2149         if (nh->fib_nh_scope == RT_SCOPE_LINK) {
2150                 struct neighbour *n;
2151
2152                 rcu_read_lock_bh();
2153
2154                 if (likely(nh->fib_nh_gw_family == AF_INET))
2155                         n = __ipv4_neigh_lookup_noref(nh->fib_nh_dev,
2156                                                    (__force u32)nh->fib_nh_gw4);
2157                 else if (nh->fib_nh_gw_family == AF_INET6)
2158                         n = __ipv6_neigh_lookup_noref_stub(nh->fib_nh_dev,
2159                                                            &nh->fib_nh_gw6);
2160                 else
2161                         n = NULL;
2162                 if (n)
2163                         state = n->nud_state;
2164
2165                 rcu_read_unlock_bh();
2166         }
2167
2168         return !!(state & NUD_VALID);
2169 }
2170
2171 void fib_select_multipath(struct fib_result *res, int hash)
2172 {
2173         struct fib_info *fi = res->fi;
2174         struct net *net = fi->fib_net;
2175         bool first = false;
2176
2177         if (unlikely(res->fi->nh)) {
2178                 nexthop_path_fib_result(res, hash);
2179                 return;
2180         }
2181
2182         change_nexthops(fi) {
2183                 if (net->ipv4.sysctl_fib_multipath_use_neigh) {
2184                         if (!fib_good_nh(nexthop_nh))
2185                                 continue;
2186                         if (!first) {
2187                                 res->nh_sel = nhsel;
2188                                 res->nhc = &nexthop_nh->nh_common;
2189                                 first = true;
2190                         }
2191                 }
2192
2193                 if (hash > atomic_read(&nexthop_nh->fib_nh_upper_bound))
2194                         continue;
2195
2196                 res->nh_sel = nhsel;
2197                 res->nhc = &nexthop_nh->nh_common;
2198                 return;
2199         } endfor_nexthops(fi);
2200 }
2201 #endif
2202
2203 void fib_select_path(struct net *net, struct fib_result *res,
2204                      struct flowi4 *fl4, const struct sk_buff *skb)
2205 {
2206         if (fl4->flowi4_oif && !(fl4->flowi4_flags & FLOWI_FLAG_SKIP_NH_OIF))
2207                 goto check_saddr;
2208
2209 #ifdef CONFIG_IP_ROUTE_MULTIPATH
2210         if (fib_info_num_path(res->fi) > 1) {
2211                 int h = fib_multipath_hash(net, fl4, skb, NULL);
2212
2213                 fib_select_multipath(res, h);
2214         }
2215         else
2216 #endif
2217         if (!res->prefixlen &&
2218             res->table->tb_num_default > 1 &&
2219             res->type == RTN_UNICAST)
2220                 fib_select_default(fl4, res);
2221
2222 check_saddr:
2223         if (!fl4->saddr)
2224                 fl4->saddr = fib_result_prefsrc(net, res);
2225 }