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 net *net, struct fib_nh_common *nhc,
 574                        struct nlattr *encap, u16 encap_type,
 575                        void *cfg, gfp_t gfp_flags,
 576                        struct netlink_ext_ack *extack)
 577 {
 578         int err;
 579
 580         nhc->nhc_pcpu_rth_output = alloc_percpu_gfp(struct rtable __rcu *,
 581                                                     gfp_flags);
 582         if (!nhc->nhc_pcpu_rth_output)
 583                 return -ENOMEM;
 584
 585         if (encap) {
 586                 struct lwtunnel_state *lwtstate;
 587
 588                 if (encap_type == LWTUNNEL_ENCAP_NONE) {
 589                         NL_SET_ERR_MSG(extack, "LWT encap type not specified");
 590                         err = -EINVAL;
 591                         goto lwt_failure;
 592                 }
 593                 err = lwtunnel_build_state(net, encap_type, encap,
 594                                            nhc->nhc_family, cfg, &lwtstate,
 595                                            extack);
 596                 if (err)
 597                         goto lwt_failure;
 598
 599                 nhc->nhc_lwtstate = lwtstate_get(lwtstate);
 600         }
 601
 602         return 0;
 603
 604 lwt_failure:
 605         rt_fibinfo_free_cpus(nhc->nhc_pcpu_rth_output);
 606         nhc->nhc_pcpu_rth_output = NULL;
 607         return err;
 608 }
 609 EXPORT_SYMBOL_GPL(fib_nh_common_init);
 610
 611 int fib_nh_init(struct net *net, struct fib_nh *nh,
 612                 struct fib_config *cfg, int nh_weight,
 613                 struct netlink_ext_ack *extack)
 614 {
 615         int err;
 616
 617         nh->fib_nh_family = AF_INET;
 618
 619         err = fib_nh_common_init(net, &nh->nh_common, cfg->fc_encap,
 620                                  cfg->fc_encap_type, cfg, GFP_KERNEL, extack);
 621         if (err)
 622                 return err;
 623
 624         nh->fib_nh_oif = cfg->fc_oif;
 625         nh->fib_nh_gw_family = cfg->fc_gw_family;
 626         if (cfg->fc_gw_family == AF_INET)
 627                 nh->fib_nh_gw4 = cfg->fc_gw4;
 628         else if (cfg->fc_gw_family == AF_INET6)
 629                 nh->fib_nh_gw6 = cfg->fc_gw6;
 630
 631         nh->fib_nh_flags = cfg->fc_flags;
 632
 633 #ifdef CONFIG_IP_ROUTE_CLASSID
 634         nh->nh_tclassid = cfg->fc_flow;
 635         if (nh->nh_tclassid)
 636                 net->ipv4.fib_num_tclassid_users++;
 637 #endif
 638 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 639         nh->fib_nh_weight = nh_weight;
 640 #endif
 641         return 0;
 642 }
 643
 644 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 645
 646 static int fib_count_nexthops(struct rtnexthop *rtnh, int remaining,
 647                               struct netlink_ext_ack *extack)
 648 {
 649         int nhs = 0;
 650
 651         while (rtnh_ok(rtnh, remaining)) {
 652                 nhs++;
 653                 rtnh = rtnh_next(rtnh, &remaining);
 654         }
 655
 656         /* leftover implies invalid nexthop configuration, discard it */
 657         if (remaining > 0) {
 658                 NL_SET_ERR_MSG(extack,
 659                                "Invalid nexthop configuration - extra data after nexthops");
 660                 nhs = 0;
 661         }
 662
 663         return nhs;
 664 }
 665
 666 /* only called when fib_nh is integrated into fib_info */
 667 static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh,
 668                        int remaining, struct fib_config *cfg,
 669                        struct netlink_ext_ack *extack)
 670 {
 671         struct net *net = fi->fib_net;
 672         struct fib_config fib_cfg;
 673         struct fib_nh *nh;
 674         int ret;
 675
 676         change_nexthops(fi) {
 677                 int attrlen;
 678
 679                 memset(&fib_cfg, 0, sizeof(fib_cfg));
 680
 681                 if (!rtnh_ok(rtnh, remaining)) {
 682                         NL_SET_ERR_MSG(extack,
 683                                        "Invalid nexthop configuration - extra data after nexthop");
 684                         return -EINVAL;
 685                 }
 686
 687                 if (rtnh->rtnh_flags & (RTNH_F_DEAD | RTNH_F_LINKDOWN)) {
 688                         NL_SET_ERR_MSG(extack,
 689                                        "Invalid flags for nexthop - can not contain DEAD or LINKDOWN");
 690                         return -EINVAL;
 691                 }
 692
 693                 fib_cfg.fc_flags = (cfg->fc_flags & ~0xFF) | rtnh->rtnh_flags;
 694                 fib_cfg.fc_oif = rtnh->rtnh_ifindex;
 695
 696                 attrlen = rtnh_attrlen(rtnh);
 697                 if (attrlen > 0) {
 698                         struct nlattr *nla, *nlav, *attrs = rtnh_attrs(rtnh);
 699
 700                         nla = nla_find(attrs, attrlen, RTA_GATEWAY);
 701                         nlav = nla_find(attrs, attrlen, RTA_VIA);
 702                         if (nla && nlav) {
 703                                 NL_SET_ERR_MSG(extack,
 704                                                "Nexthop configuration can not contain both GATEWAY and VIA");
 705                                 return -EINVAL;
 706                         }
 707                         if (nla) {
 708                                 fib_cfg.fc_gw4 = nla_get_in_addr(nla);
 709                                 if (fib_cfg.fc_gw4)
 710                                         fib_cfg.fc_gw_family = AF_INET;
 711                         } else if (nlav) {
 712                                 ret = fib_gw_from_via(&fib_cfg, nlav, extack);
 713                                 if (ret)
 714                                         goto errout;
 715                         }
 716
 717                         nla = nla_find(attrs, attrlen, RTA_FLOW);
 718                         if (nla)
 719                                 fib_cfg.fc_flow = nla_get_u32(nla);
 720
 721                         fib_cfg.fc_encap = nla_find(attrs, attrlen, RTA_ENCAP);
 722                         nla = nla_find(attrs, attrlen, RTA_ENCAP_TYPE);
 723                         if (nla)
 724                                 fib_cfg.fc_encap_type = nla_get_u16(nla);
 725                 }
 726
 727                 ret = fib_nh_init(net, nexthop_nh, &fib_cfg,
 728                                   rtnh->rtnh_hops + 1, extack);
 729                 if (ret)
 730                         goto errout;
 731
 732                 rtnh = rtnh_next(rtnh, &remaining);
 733         } endfor_nexthops(fi);
 734
 735         ret = -EINVAL;
 736         nh = fib_info_nh(fi, 0);
 737         if (cfg->fc_oif && nh->fib_nh_oif != cfg->fc_oif) {
 738                 NL_SET_ERR_MSG(extack,
 739                                "Nexthop device index does not match RTA_OIF");
 740                 goto errout;
 741         }
 742         if (cfg->fc_gw_family) {
 743                 if (cfg->fc_gw_family != nh->fib_nh_gw_family ||
 744                     (cfg->fc_gw_family == AF_INET &&
 745                      nh->fib_nh_gw4 != cfg->fc_gw4) ||
 746                     (cfg->fc_gw_family == AF_INET6 &&
 747                      ipv6_addr_cmp(&nh->fib_nh_gw6, &cfg->fc_gw6))) {
 748                         NL_SET_ERR_MSG(extack,
 749                                        "Nexthop gateway does not match RTA_GATEWAY or RTA_VIA");
 750                         goto errout;
 751                 }
 752         }
 753 #ifdef CONFIG_IP_ROUTE_CLASSID
 754         if (cfg->fc_flow && nh->nh_tclassid != cfg->fc_flow) {
 755                 NL_SET_ERR_MSG(extack,
 756                                "Nexthop class id does not match RTA_FLOW");
 757                 goto errout;
 758         }
 759 #endif
 760         ret = 0;
 761 errout:
 762         return ret;
 763 }
 764
 765 /* only called when fib_nh is integrated into fib_info */
 766 static void fib_rebalance(struct fib_info *fi)
 767 {
 768         int total;
 769         int w;
 770
 771         if (fib_info_num_path(fi) < 2)
 772                 return;
 773
 774         total = 0;
 775         for_nexthops(fi) {
 776                 if (nh->fib_nh_flags & RTNH_F_DEAD)
 777                         continue;
 778
 779                 if (ip_ignore_linkdown(nh->fib_nh_dev) &&
 780                     nh->fib_nh_flags & RTNH_F_LINKDOWN)
 781                         continue;
 782
 783                 total += nh->fib_nh_weight;
 784         } endfor_nexthops(fi);
 785
 786         w = 0;
 787         change_nexthops(fi) {
 788                 int upper_bound;
 789
 790                 if (nexthop_nh->fib_nh_flags & RTNH_F_DEAD) {
 791                         upper_bound = -1;
 792                 } else if (ip_ignore_linkdown(nexthop_nh->fib_nh_dev) &&
 793                            nexthop_nh->fib_nh_flags & RTNH_F_LINKDOWN) {
 794                         upper_bound = -1;
 795                 } else {
 796                         w += nexthop_nh->fib_nh_weight;
 797                         upper_bound = DIV_ROUND_CLOSEST_ULL((u64)w << 31,
 798                                                             total) - 1;
 799                 }
 800
 801                 atomic_set(&nexthop_nh->fib_nh_upper_bound, upper_bound);
 802         } endfor_nexthops(fi);
 803 }
 804 #else /* CONFIG_IP_ROUTE_MULTIPATH */
 805
 806 static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh,
 807                        int remaining, struct fib_config *cfg,
 808                        struct netlink_ext_ack *extack)
 809 {
 810         NL_SET_ERR_MSG(extack, "Multipath support not enabled in kernel");
 811
 812         return -EINVAL;
 813 }
 814
 815 #define fib_rebalance(fi) do { } while (0)
 816
 817 #endif /* CONFIG_IP_ROUTE_MULTIPATH */
 818
 819 static int fib_encap_match(struct net *net, u16 encap_type,
 820                            struct nlattr *encap,
 821                            const struct fib_nh *nh,
 822                            const struct fib_config *cfg,
 823                            struct netlink_ext_ack *extack)
 824 {
 825         struct lwtunnel_state *lwtstate;
 826         int ret, result = 0;
 827
 828         if (encap_type == LWTUNNEL_ENCAP_NONE)
 829                 return 0;
 830
 831         ret = lwtunnel_build_state(net, encap_type, encap, AF_INET,
 832                                    cfg, &lwtstate, extack);
 833         if (!ret) {
 834                 result = lwtunnel_cmp_encap(lwtstate, nh->fib_nh_lws);
 835                 lwtstate_free(lwtstate);
 836         }
 837
 838         return result;
 839 }
 840
 841 int fib_nh_match(struct net *net, struct fib_config *cfg, struct fib_info *fi,
 842                  struct netlink_ext_ack *extack)
 843 {
 844 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 845         struct rtnexthop *rtnh;
 846         int remaining;
 847 #endif
 848
 849         if (cfg->fc_priority && cfg->fc_priority != fi->fib_priority)
 850                 return 1;
 851
 852         if (cfg->fc_nh_id) {
 853                 if (fi->nh && cfg->fc_nh_id == fi->nh->id)
 854                         return 0;
 855                 return 1;
 856         }
 857
 858         if (cfg->fc_oif || cfg->fc_gw_family) {
 859                 struct fib_nh *nh = fib_info_nh(fi, 0);
 860
 861                 if (cfg->fc_encap) {
 862                         if (fib_encap_match(net, cfg->fc_encap_type,
 863                                             cfg->fc_encap, nh, cfg, extack))
 864                                 return 1;
 865                 }
 866 #ifdef CONFIG_IP_ROUTE_CLASSID
 867                 if (cfg->fc_flow &&
 868                     cfg->fc_flow != nh->nh_tclassid)
 869                         return 1;
 870 #endif
 871                 if ((cfg->fc_oif && cfg->fc_oif != nh->fib_nh_oif) ||
 872                     (cfg->fc_gw_family &&
 873                      cfg->fc_gw_family != nh->fib_nh_gw_family))
 874                         return 1;
 875
 876                 if (cfg->fc_gw_family == AF_INET &&
 877                     cfg->fc_gw4 != nh->fib_nh_gw4)
 878                         return 1;
 879
 880                 if (cfg->fc_gw_family == AF_INET6 &&
 881                     ipv6_addr_cmp(&cfg->fc_gw6, &nh->fib_nh_gw6))
 882                         return 1;
 883
 884                 return 0;
 885         }
 886
 887 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 888         if (!cfg->fc_mp)
 889                 return 0;
 890
 891         rtnh = cfg->fc_mp;
 892         remaining = cfg->fc_mp_len;
 893
 894         for_nexthops(fi) {
 895                 int attrlen;
 896
 897                 if (!rtnh_ok(rtnh, remaining))
 898                         return -EINVAL;
 899
 900                 if (rtnh->rtnh_ifindex && rtnh->rtnh_ifindex != nh->fib_nh_oif)
 901                         return 1;
 902
 903                 attrlen = rtnh_attrlen(rtnh);
 904                 if (attrlen > 0) {
 905                         struct nlattr *nla, *nlav, *attrs = rtnh_attrs(rtnh);
 906
 907                         nla = nla_find(attrs, attrlen, RTA_GATEWAY);
 908                         nlav = nla_find(attrs, attrlen, RTA_VIA);
 909                         if (nla && nlav) {
 910                                 NL_SET_ERR_MSG(extack,
 911                                                "Nexthop configuration can not contain both GATEWAY and VIA");
 912                                 return -EINVAL;
 913                         }
 914
 915                         if (nla) {
 916                                 if (nh->fib_nh_gw_family != AF_INET ||
 917                                     nla_get_in_addr(nla) != nh->fib_nh_gw4)
 918                                         return 1;
 919                         } else if (nlav) {
 920                                 struct fib_config cfg2;
 921                                 int err;
 922
 923                                 err = fib_gw_from_via(&cfg2, nlav, extack);
 924                                 if (err)
 925                                         return err;
 926
 927                                 switch (nh->fib_nh_gw_family) {
 928                                 case AF_INET:
 929                                         if (cfg2.fc_gw_family != AF_INET ||
 930                                             cfg2.fc_gw4 != nh->fib_nh_gw4)
 931                                                 return 1;
 932                                         break;
 933                                 case AF_INET6:
 934                                         if (cfg2.fc_gw_family != AF_INET6 ||
 935                                             ipv6_addr_cmp(&cfg2.fc_gw6,
 936                                                           &nh->fib_nh_gw6))
 937                                                 return 1;
 938                                         break;
 939                                 }
 940                         }
 941
 942 #ifdef CONFIG_IP_ROUTE_CLASSID
 943                         nla = nla_find(attrs, attrlen, RTA_FLOW);
 944                         if (nla && nla_get_u32(nla) != nh->nh_tclassid)
 945                                 return 1;
 946 #endif
 947                 }
 948
 949                 rtnh = rtnh_next(rtnh, &remaining);
 950         } endfor_nexthops(fi);
 951 #endif
 952         return 0;
 953 }
 954
 955 bool fib_metrics_match(struct fib_config *cfg, struct fib_info *fi)
 956 {
 957         struct nlattr *nla;
 958         int remaining;
 959
 960         if (!cfg->fc_mx)
 961                 return true;
 962
 963         nla_for_each_attr(nla, cfg->fc_mx, cfg->fc_mx_len, remaining) {
 964                 int type = nla_type(nla);
 965                 u32 fi_val, val;
 966
 967                 if (!type)
 968                         continue;
 969                 if (type > RTAX_MAX)
 970                         return false;
 971
 972                 if (type == RTAX_CC_ALGO) {
 973                         char tmp[TCP_CA_NAME_MAX];
 974                         bool ecn_ca = false;
 975
 976                         nla_strscpy(tmp, nla, sizeof(tmp));
 977                         val = tcp_ca_get_key_by_name(fi->fib_net, tmp, &ecn_ca);
 978                 } else {
 979                         if (nla_len(nla) != sizeof(u32))
 980                                 return false;
 981                         val = nla_get_u32(nla);
 982                 }
 983
 984                 fi_val = fi->fib_metrics->metrics[type - 1];
 985                 if (type == RTAX_FEATURES)
 986                         fi_val &= ~DST_FEATURE_ECN_CA;
 987
 988                 if (fi_val != val)
 989                         return false;
 990         }
 991
 992         return true;
 993 }
 994
 995 static int fib_check_nh_v6_gw(struct net *net, struct fib_nh *nh,
 996                               u32 table, struct netlink_ext_ack *extack)
 997 {
 998         struct fib6_config cfg = {
 999                 .fc_table = table,
1000                 .fc_flags = nh->fib_nh_flags | RTF_GATEWAY,
1001                 .fc_ifindex = nh->fib_nh_oif,
1002                 .fc_gateway = nh->fib_nh_gw6,
1003         };
1004         struct fib6_nh fib6_nh = {};
1005         int err;
1006
1007         err = ipv6_stub->fib6_nh_init(net, &fib6_nh, &cfg, GFP_KERNEL, extack);
1008         if (!err) {
1009                 nh->fib_nh_dev = fib6_nh.fib_nh_dev;
1010                 dev_hold(nh->fib_nh_dev);
1011                 nh->fib_nh_oif = nh->fib_nh_dev->ifindex;
1012                 nh->fib_nh_scope = RT_SCOPE_LINK;
1013
1014                 ipv6_stub->fib6_nh_release(&fib6_nh);
1015         }
1016
1017         return err;
1018 }
1019
1020 /*
1021  * Picture
1022  * -------
1023  *
1024  * Semantics of nexthop is very messy by historical reasons.
1025  * We have to take into account, that:
1026  * a) gateway can be actually local interface address,
1027  *    so that gatewayed route is direct.
1028  * b) gateway must be on-link address, possibly
1029  *    described not by an ifaddr, but also by a direct route.
1030  * c) If both gateway and interface are specified, they should not
1031  *    contradict.
1032  * d) If we use tunnel routes, gateway could be not on-link.
1033  *
1034  * Attempt to reconcile all of these (alas, self-contradictory) conditions
1035  * results in pretty ugly and hairy code with obscure logic.
1036  *
1037  * I chose to generalized it instead, so that the size
1038  * of code does not increase practically, but it becomes
1039  * much more general.
1040  * Every prefix is assigned a "scope" value: "host" is local address,
1041  * "link" is direct route,
1042  * [ ... "site" ... "interior" ... ]
1043  * and "universe" is true gateway route with global meaning.
1044  *
1045  * Every prefix refers to a set of "nexthop"s (gw, oif),
1046  * where gw must have narrower scope. This recursion stops
1047  * when gw has LOCAL scope or if "nexthop" is declared ONLINK,
1048  * which means that gw is forced to be on link.
1049  *
1050  * Code is still hairy, but now it is apparently logically
1051  * consistent and very flexible. F.e. as by-product it allows
1052  * to co-exists in peace independent exterior and interior
1053  * routing processes.
1054  *
1055  * Normally it looks as following.
1056  *
1057  * {universe prefix}  -> (gw, oif) [scope link]
1058  *                |
1059  *                |-> {link prefix} -> (gw, oif) [scope local]
1060  *                                      |
1061  *                                      |-> {local prefix} (terminal node)
1062  */
1063 static int fib_check_nh_v4_gw(struct net *net, struct fib_nh *nh, u32 table,
1064                               u8 scope, struct netlink_ext_ack *extack)
1065 {
1066         struct net_device *dev;
1067         struct fib_result res;
1068         int err = 0;
1069
1070         if (nh->fib_nh_flags & RTNH_F_ONLINK) {
1071                 unsigned int addr_type;
1072
1073                 if (scope >= RT_SCOPE_LINK) {
1074                         NL_SET_ERR_MSG(extack, "Nexthop has invalid scope");
1075                         return -EINVAL;
1076                 }
1077                 dev = __dev_get_by_index(net, nh->fib_nh_oif);
1078                 if (!dev) {
1079                         NL_SET_ERR_MSG(extack, "Nexthop device required for onlink");
1080                         return -ENODEV;
1081                 }
1082                 if (!(dev->flags & IFF_UP)) {
1083                         NL_SET_ERR_MSG(extack, "Nexthop device is not up");
1084                         return -ENETDOWN;
1085                 }
1086                 addr_type = inet_addr_type_dev_table(net, dev, nh->fib_nh_gw4);
1087                 if (addr_type != RTN_UNICAST) {
1088                         NL_SET_ERR_MSG(extack, "Nexthop has invalid gateway");
1089                         return -EINVAL;
1090                 }
1091                 if (!netif_carrier_ok(dev))
1092                         nh->fib_nh_flags |= RTNH_F_LINKDOWN;
1093                 nh->fib_nh_dev = dev;
1094                 dev_hold(dev);
1095                 nh->fib_nh_scope = RT_SCOPE_LINK;
1096                 return 0;
1097         }
1098         rcu_read_lock();
1099         {
1100                 struct fib_table *tbl = NULL;
1101                 struct flowi4 fl4 = {
1102                         .daddr = nh->fib_nh_gw4,
1103                         .flowi4_scope = scope + 1,
1104                         .flowi4_oif = nh->fib_nh_oif,
1105                         .flowi4_iif = LOOPBACK_IFINDEX,
1106                 };
1107
1108                 /* It is not necessary, but requires a bit of thinking */
1109                 if (fl4.flowi4_scope < RT_SCOPE_LINK)
1110                         fl4.flowi4_scope = RT_SCOPE_LINK;
1111
1112                 if (table && table != RT_TABLE_MAIN)
1113                         tbl = fib_get_table(net, table);
1114
1115                 if (tbl)
1116                         err = fib_table_lookup(tbl, &fl4, &res,
1117                                                FIB_LOOKUP_IGNORE_LINKSTATE |
1118                                                FIB_LOOKUP_NOREF);
1119
1120                 /* on error or if no table given do full lookup. This
1121                  * is needed for example when nexthops are in the local
1122                  * table rather than the given table
1123                  */
1124                 if (!tbl || err) {
1125                         err = fib_lookup(net, &fl4, &res,
1126                                          FIB_LOOKUP_IGNORE_LINKSTATE);
1127                 }
1128
1129                 if (err) {
1130                         NL_SET_ERR_MSG(extack, "Nexthop has invalid gateway");
1131                         goto out;
1132                 }
1133         }
1134
1135         err = -EINVAL;
1136         if (res.type != RTN_UNICAST && res.type != RTN_LOCAL) {
1137                 NL_SET_ERR_MSG(extack, "Nexthop has invalid gateway");
1138                 goto out;
1139         }
1140         nh->fib_nh_scope = res.scope;
1141         nh->fib_nh_oif = FIB_RES_OIF(res);
1142         nh->fib_nh_dev = dev = FIB_RES_DEV(res);
1143         if (!dev) {
1144                 NL_SET_ERR_MSG(extack,
1145                                "No egress device for nexthop gateway");
1146                 goto out;
1147         }
1148         dev_hold(dev);
1149         if (!netif_carrier_ok(dev))
1150                 nh->fib_nh_flags |= RTNH_F_LINKDOWN;
1151         err = (dev->flags & IFF_UP) ? 0 : -ENETDOWN;
1152 out:
1153         rcu_read_unlock();
1154         return err;
1155 }
1156
1157 static int fib_check_nh_nongw(struct net *net, struct fib_nh *nh,
1158                               struct netlink_ext_ack *extack)
1159 {
1160         struct in_device *in_dev;
1161         int err;
1162
1163         if (nh->fib_nh_flags & (RTNH_F_PERVASIVE | RTNH_F_ONLINK)) {
1164                 NL_SET_ERR_MSG(extack,
1165                                "Invalid flags for nexthop - PERVASIVE and ONLINK can not be set");
1166                 return -EINVAL;
1167         }
1168
1169         rcu_read_lock();
1170
1171         err = -ENODEV;
1172         in_dev = inetdev_by_index(net, nh->fib_nh_oif);
1173         if (!in_dev)
1174                 goto out;
1175         err = -ENETDOWN;
1176         if (!(in_dev->dev->flags & IFF_UP)) {
1177                 NL_SET_ERR_MSG(extack, "Device for nexthop is not up");
1178                 goto out;
1179         }
1180
1181         nh->fib_nh_dev = in_dev->dev;
1182         dev_hold(nh->fib_nh_dev);
1183         nh->fib_nh_scope = RT_SCOPE_HOST;
1184         if (!netif_carrier_ok(nh->fib_nh_dev))
1185                 nh->fib_nh_flags |= RTNH_F_LINKDOWN;
1186         err = 0;
1187 out:
1188         rcu_read_unlock();
1189         return err;
1190 }
1191
1192 int fib_check_nh(struct net *net, struct fib_nh *nh, u32 table, u8 scope,
1193                  struct netlink_ext_ack *extack)
1194 {
1195         int err;
1196
1197         if (nh->fib_nh_gw_family == AF_INET)
1198                 err = fib_check_nh_v4_gw(net, nh, table, scope, extack);
1199         else if (nh->fib_nh_gw_family == AF_INET6)
1200                 err = fib_check_nh_v6_gw(net, nh, table, extack);
1201         else
1202                 err = fib_check_nh_nongw(net, nh, extack);
1203
1204         return err;
1205 }
1206
1207 static inline unsigned int fib_laddr_hashfn(__be32 val)
1208 {
1209         unsigned int mask = (fib_info_hash_size - 1);
1210
1211         return ((__force u32)val ^
1212                 ((__force u32)val >> 7) ^
1213                 ((__force u32)val >> 14)) & mask;
1214 }
1215
1216 static struct hlist_head *fib_info_hash_alloc(int bytes)
1217 {
1218         if (bytes <= PAGE_SIZE)
1219                 return kzalloc(bytes, GFP_KERNEL);
1220         else
1221                 return (struct hlist_head *)
1222                         __get_free_pages(GFP_KERNEL | __GFP_ZERO,
1223                                          get_order(bytes));
1224 }
1225
1226 static void fib_info_hash_free(struct hlist_head *hash, int bytes)
1227 {
1228         if (!hash)
1229                 return;
1230
1231         if (bytes <= PAGE_SIZE)
1232                 kfree(hash);
1233         else
1234                 free_pages((unsigned long) hash, get_order(bytes));
1235 }
1236
1237 static void fib_info_hash_move(struct hlist_head *new_info_hash,
1238                                struct hlist_head *new_laddrhash,
1239                                unsigned int new_size)
1240 {
1241         struct hlist_head *old_info_hash, *old_laddrhash;
1242         unsigned int old_size = fib_info_hash_size;
1243         unsigned int i, bytes;
1244
1245         spin_lock_bh(&fib_info_lock);
1246         old_info_hash = fib_info_hash;
1247         old_laddrhash = fib_info_laddrhash;
1248         fib_info_hash_size = new_size;
1249
1250         for (i = 0; i < old_size; i++) {
1251                 struct hlist_head *head = &fib_info_hash[i];
1252                 struct hlist_node *n;
1253                 struct fib_info *fi;
1254
1255                 hlist_for_each_entry_safe(fi, n, head, fib_hash) {
1256                         struct hlist_head *dest;
1257                         unsigned int new_hash;
1258
1259                         new_hash = fib_info_hashfn(fi);
1260                         dest = &new_info_hash[new_hash];
1261                         hlist_add_head(&fi->fib_hash, dest);
1262                 }
1263         }
1264         fib_info_hash = new_info_hash;
1265
1266         for (i = 0; i < old_size; i++) {
1267                 struct hlist_head *lhead = &fib_info_laddrhash[i];
1268                 struct hlist_node *n;
1269                 struct fib_info *fi;
1270
1271                 hlist_for_each_entry_safe(fi, n, lhead, fib_lhash) {
1272                         struct hlist_head *ldest;
1273                         unsigned int new_hash;
1274
1275                         new_hash = fib_laddr_hashfn(fi->fib_prefsrc);
1276                         ldest = &new_laddrhash[new_hash];
1277                         hlist_add_head(&fi->fib_lhash, ldest);
1278                 }
1279         }
1280         fib_info_laddrhash = new_laddrhash;
1281
1282         spin_unlock_bh(&fib_info_lock);
1283
1284         bytes = old_size * sizeof(struct hlist_head *);
1285         fib_info_hash_free(old_info_hash, bytes);
1286         fib_info_hash_free(old_laddrhash, bytes);
1287 }
1288
1289 __be32 fib_info_update_nhc_saddr(struct net *net, struct fib_nh_common *nhc,
1290                                  unsigned char scope)
1291 {
1292         struct fib_nh *nh;
1293
1294         if (nhc->nhc_family != AF_INET)
1295                 return inet_select_addr(nhc->nhc_dev, 0, scope);
1296
1297         nh = container_of(nhc, struct fib_nh, nh_common);
1298         nh->nh_saddr = inet_select_addr(nh->fib_nh_dev, nh->fib_nh_gw4, scope);
1299         nh->nh_saddr_genid = atomic_read(&net->ipv4.dev_addr_genid);
1300
1301         return nh->nh_saddr;
1302 }
1303
1304 __be32 fib_result_prefsrc(struct net *net, struct fib_result *res)
1305 {
1306         struct fib_nh_common *nhc = res->nhc;
1307
1308         if (res->fi->fib_prefsrc)
1309                 return res->fi->fib_prefsrc;
1310
1311         if (nhc->nhc_family == AF_INET) {
1312                 struct fib_nh *nh;
1313
1314                 nh = container_of(nhc, struct fib_nh, nh_common);
1315                 if (nh->nh_saddr_genid == atomic_read(&net->ipv4.dev_addr_genid))
1316                         return nh->nh_saddr;
1317         }
1318
1319         return fib_info_update_nhc_saddr(net, nhc, res->fi->fib_scope);
1320 }
1321
1322 static bool fib_valid_prefsrc(struct fib_config *cfg, __be32 fib_prefsrc)
1323 {
1324         if (cfg->fc_type != RTN_LOCAL || !cfg->fc_dst ||
1325             fib_prefsrc != cfg->fc_dst) {
1326                 u32 tb_id = cfg->fc_table;
1327                 int rc;
1328
1329                 if (tb_id == RT_TABLE_MAIN)
1330                         tb_id = RT_TABLE_LOCAL;
1331
1332                 rc = inet_addr_type_table(cfg->fc_nlinfo.nl_net,
1333                                           fib_prefsrc, tb_id);
1334
1335                 if (rc != RTN_LOCAL && tb_id != RT_TABLE_LOCAL) {
1336                         rc = inet_addr_type_table(cfg->fc_nlinfo.nl_net,
1337                                                   fib_prefsrc, RT_TABLE_LOCAL);
1338                 }
1339
1340                 if (rc != RTN_LOCAL)
1341                         return false;
1342         }
1343         return true;
1344 }
1345
1346 struct fib_info *fib_create_info(struct fib_config *cfg,
1347                                  struct netlink_ext_ack *extack)
1348 {
1349         int err;
1350         struct fib_info *fi = NULL;
1351         struct nexthop *nh = NULL;
1352         struct fib_info *ofi;
1353         int nhs = 1;
1354         struct net *net = cfg->fc_nlinfo.nl_net;
1355
1356         if (cfg->fc_type > RTN_MAX)
1357                 goto err_inval;
1358
1359         /* Fast check to catch the most weird cases */
1360         if (fib_props[cfg->fc_type].scope > cfg->fc_scope) {
1361                 NL_SET_ERR_MSG(extack, "Invalid scope");
1362                 goto err_inval;
1363         }
1364
1365         if (cfg->fc_flags & (RTNH_F_DEAD | RTNH_F_LINKDOWN)) {
1366                 NL_SET_ERR_MSG(extack,
1367                                "Invalid rtm_flags - can not contain DEAD or LINKDOWN");
1368                 goto err_inval;
1369         }
1370
1371         if (cfg->fc_nh_id) {
1372                 if (!cfg->fc_mx) {
1373                         fi = fib_find_info_nh(net, cfg);
1374                         if (fi) {
1375                                 fi->fib_treeref++;
1376                                 return fi;
1377                         }
1378                 }
1379
1380                 nh = nexthop_find_by_id(net, cfg->fc_nh_id);
1381                 if (!nh) {
1382                         NL_SET_ERR_MSG(extack, "Nexthop id does not exist");
1383                         goto err_inval;
1384                 }
1385                 nhs = 0;
1386         }
1387
1388 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1389         if (cfg->fc_mp) {
1390                 nhs = fib_count_nexthops(cfg->fc_mp, cfg->fc_mp_len, extack);
1391                 if (nhs == 0)
1392                         goto err_inval;
1393         }
1394 #endif
1395
1396         err = -ENOBUFS;
1397         if (fib_info_cnt >= fib_info_hash_size) {
1398                 unsigned int new_size = fib_info_hash_size << 1;
1399                 struct hlist_head *new_info_hash;
1400                 struct hlist_head *new_laddrhash;
1401                 unsigned int bytes;
1402
1403                 if (!new_size)
1404                         new_size = 16;
1405                 bytes = new_size * sizeof(struct hlist_head *);
1406                 new_info_hash = fib_info_hash_alloc(bytes);
1407                 new_laddrhash = fib_info_hash_alloc(bytes);
1408                 if (!new_info_hash || !new_laddrhash) {
1409                         fib_info_hash_free(new_info_hash, bytes);
1410                         fib_info_hash_free(new_laddrhash, bytes);
1411                 } else
1412                         fib_info_hash_move(new_info_hash, new_laddrhash, new_size);
1413
1414                 if (!fib_info_hash_size)
1415                         goto failure;
1416         }
1417
1418         fi = kzalloc(struct_size(fi, fib_nh, nhs), GFP_KERNEL);
1419         if (!fi)
1420                 goto failure;
1421         fi->fib_metrics = ip_fib_metrics_init(fi->fib_net, cfg->fc_mx,
1422                                               cfg->fc_mx_len, extack);
1423         if (IS_ERR(fi->fib_metrics)) {
1424                 err = PTR_ERR(fi->fib_metrics);
1425                 kfree(fi);
1426                 return ERR_PTR(err);
1427         }
1428
1429         fib_info_cnt++;
1430         fi->fib_net = net;
1431         fi->fib_protocol = cfg->fc_protocol;
1432         fi->fib_scope = cfg->fc_scope;
1433         fi->fib_flags = cfg->fc_flags;
1434         fi->fib_priority = cfg->fc_priority;
1435         fi->fib_prefsrc = cfg->fc_prefsrc;
1436         fi->fib_type = cfg->fc_type;
1437         fi->fib_tb_id = cfg->fc_table;
1438
1439         fi->fib_nhs = nhs;
1440         if (nh) {
1441                 if (!nexthop_get(nh)) {
1442                         NL_SET_ERR_MSG(extack, "Nexthop has been deleted");
1443                         err = -EINVAL;
1444                 } else {
1445                         err = 0;
1446                         fi->nh = nh;
1447                 }
1448         } else {
1449                 change_nexthops(fi) {
1450                         nexthop_nh->nh_parent = fi;
1451                 } endfor_nexthops(fi)
1452
1453                 if (cfg->fc_mp)
1454                         err = fib_get_nhs(fi, cfg->fc_mp, cfg->fc_mp_len, cfg,
1455                                           extack);
1456                 else
1457                         err = fib_nh_init(net, fi->fib_nh, cfg, 1, extack);
1458         }
1459
1460         if (err != 0)
1461                 goto failure;
1462
1463         if (fib_props[cfg->fc_type].error) {
1464                 if (cfg->fc_gw_family || cfg->fc_oif || cfg->fc_mp) {
1465                         NL_SET_ERR_MSG(extack,
1466                                        "Gateway, device and multipath can not be specified for this route type");
1467                         goto err_inval;
1468                 }
1469                 goto link_it;
1470         } else {
1471                 switch (cfg->fc_type) {
1472                 case RTN_UNICAST:
1473                 case RTN_LOCAL:
1474                 case RTN_BROADCAST:
1475                 case RTN_ANYCAST:
1476                 case RTN_MULTICAST:
1477                         break;
1478                 default:
1479                         NL_SET_ERR_MSG(extack, "Invalid route type");
1480                         goto err_inval;
1481                 }
1482         }
1483
1484         if (cfg->fc_scope > RT_SCOPE_HOST) {
1485                 NL_SET_ERR_MSG(extack, "Invalid scope");
1486                 goto err_inval;
1487         }
1488
1489         if (fi->nh) {
1490                 err = fib_check_nexthop(fi->nh, cfg->fc_scope, extack);
1491                 if (err)
1492                         goto failure;
1493         } else if (cfg->fc_scope == RT_SCOPE_HOST) {
1494                 struct fib_nh *nh = fi->fib_nh;
1495
1496                 /* Local address is added. */
1497                 if (nhs != 1) {
1498                         NL_SET_ERR_MSG(extack,
1499                                        "Route with host scope can not have multiple nexthops");
1500                         goto err_inval;
1501                 }
1502                 if (nh->fib_nh_gw_family) {
1503                         NL_SET_ERR_MSG(extack,
1504                                        "Route with host scope can not have a gateway");
1505                         goto err_inval;
1506                 }
1507                 nh->fib_nh_scope = RT_SCOPE_NOWHERE;
1508                 nh->fib_nh_dev = dev_get_by_index(net, nh->fib_nh_oif);
1509                 err = -ENODEV;
1510                 if (!nh->fib_nh_dev)
1511                         goto failure;
1512         } else {
1513                 int linkdown = 0;
1514
1515                 change_nexthops(fi) {
1516                         err = fib_check_nh(cfg->fc_nlinfo.nl_net, nexthop_nh,
1517                                            cfg->fc_table, cfg->fc_scope,
1518                                            extack);
1519                         if (err != 0)
1520                                 goto failure;
1521                         if (nexthop_nh->fib_nh_flags & RTNH_F_LINKDOWN)
1522                                 linkdown++;
1523                 } endfor_nexthops(fi)
1524                 if (linkdown == fi->fib_nhs)
1525                         fi->fib_flags |= RTNH_F_LINKDOWN;
1526         }
1527
1528         if (fi->fib_prefsrc && !fib_valid_prefsrc(cfg, fi->fib_prefsrc)) {
1529                 NL_SET_ERR_MSG(extack, "Invalid prefsrc address");
1530                 goto err_inval;
1531         }
1532
1533         if (!fi->nh) {
1534                 change_nexthops(fi) {
1535                         fib_info_update_nhc_saddr(net, &nexthop_nh->nh_common,
1536                                                   fi->fib_scope);
1537                         if (nexthop_nh->fib_nh_gw_family == AF_INET6)
1538                                 fi->fib_nh_is_v6 = true;
1539                 } endfor_nexthops(fi)
1540
1541                 fib_rebalance(fi);
1542         }
1543
1544 link_it:
1545         ofi = fib_find_info(fi);
1546         if (ofi) {
1547                 fi->fib_dead = 1;
1548                 free_fib_info(fi);
1549                 ofi->fib_treeref++;
1550                 return ofi;
1551         }
1552
1553         fi->fib_treeref++;
1554         refcount_set(&fi->fib_clntref, 1);
1555         spin_lock_bh(&fib_info_lock);
1556         hlist_add_head(&fi->fib_hash,
1557                        &fib_info_hash[fib_info_hashfn(fi)]);
1558         if (fi->fib_prefsrc) {
1559                 struct hlist_head *head;
1560
1561                 head = &fib_info_laddrhash[fib_laddr_hashfn(fi->fib_prefsrc)];
1562                 hlist_add_head(&fi->fib_lhash, head);
1563         }
1564         if (fi->nh) {
1565                 list_add(&fi->nh_list, &nh->fi_list);
1566         } else {
1567                 change_nexthops(fi) {
1568                         struct hlist_head *head;
1569                         unsigned int hash;
1570
1571                         if (!nexthop_nh->fib_nh_dev)
1572                                 continue;
1573                         hash = fib_devindex_hashfn(nexthop_nh->fib_nh_dev->ifindex);
1574                         head = &fib_info_devhash[hash];
1575                         hlist_add_head(&nexthop_nh->nh_hash, head);
1576                 } endfor_nexthops(fi)
1577         }
1578         spin_unlock_bh(&fib_info_lock);
1579         return fi;
1580
1581 err_inval:
1582         err = -EINVAL;
1583
1584 failure:
1585         if (fi) {
1586                 fi->fib_dead = 1;
1587                 free_fib_info(fi);
1588         }
1589
1590         return ERR_PTR(err);
1591 }
1592
1593 int fib_nexthop_info(struct sk_buff *skb, const struct fib_nh_common *nhc,
1594                      u8 rt_family, unsigned char *flags, bool skip_oif)
1595 {
1596         if (nhc->nhc_flags & RTNH_F_DEAD)
1597                 *flags |= RTNH_F_DEAD;
1598
1599         if (nhc->nhc_flags & RTNH_F_LINKDOWN) {
1600                 *flags |= RTNH_F_LINKDOWN;
1601
1602                 rcu_read_lock();
1603                 switch (nhc->nhc_family) {
1604                 case AF_INET:
1605                         if (ip_ignore_linkdown(nhc->nhc_dev))
1606                                 *flags |= RTNH_F_DEAD;
1607                         break;
1608                 case AF_INET6:
1609                         if (ip6_ignore_linkdown(nhc->nhc_dev))
1610                                 *flags |= RTNH_F_DEAD;
1611                         break;
1612                 }
1613                 rcu_read_unlock();
1614         }
1615
1616         switch (nhc->nhc_gw_family) {
1617         case AF_INET:
1618                 if (nla_put_in_addr(skb, RTA_GATEWAY, nhc->nhc_gw.ipv4))
1619                         goto nla_put_failure;
1620                 break;
1621         case AF_INET6:
1622                 /* if gateway family does not match nexthop family
1623                  * gateway is encoded as RTA_VIA
1624                  */
1625                 if (rt_family != nhc->nhc_gw_family) {
1626                         int alen = sizeof(struct in6_addr);
1627                         struct nlattr *nla;
1628                         struct rtvia *via;
1629
1630                         nla = nla_reserve(skb, RTA_VIA, alen + 2);
1631                         if (!nla)
1632                                 goto nla_put_failure;
1633
1634                         via = nla_data(nla);
1635                         via->rtvia_family = AF_INET6;
1636                         memcpy(via->rtvia_addr, &nhc->nhc_gw.ipv6, alen);
1637                 } else if (nla_put_in6_addr(skb, RTA_GATEWAY,
1638                                             &nhc->nhc_gw.ipv6) < 0) {
1639                         goto nla_put_failure;
1640                 }
1641                 break;
1642         }
1643
1644         *flags |= (nhc->nhc_flags &
1645                    (RTNH_F_ONLINK | RTNH_F_OFFLOAD | RTNH_F_TRAP));
1646
1647         if (!skip_oif && nhc->nhc_dev &&
1648             nla_put_u32(skb, RTA_OIF, nhc->nhc_dev->ifindex))
1649                 goto nla_put_failure;
1650
1651         if (nhc->nhc_lwtstate &&
1652             lwtunnel_fill_encap(skb, nhc->nhc_lwtstate,
1653                                 RTA_ENCAP, RTA_ENCAP_TYPE) < 0)
1654                 goto nla_put_failure;
1655
1656         return 0;
1657
1658 nla_put_failure:
1659         return -EMSGSIZE;
1660 }
1661 EXPORT_SYMBOL_GPL(fib_nexthop_info);
1662
1663 #if IS_ENABLED(CONFIG_IP_ROUTE_MULTIPATH) || IS_ENABLED(CONFIG_IPV6)
1664 int fib_add_nexthop(struct sk_buff *skb, const struct fib_nh_common *nhc,
1665                     int nh_weight, u8 rt_family)
1666 {
1667         const struct net_device *dev = nhc->nhc_dev;
1668         struct rtnexthop *rtnh;
1669         unsigned char flags = 0;
1670
1671         rtnh = nla_reserve_nohdr(skb, sizeof(*rtnh));
1672         if (!rtnh)
1673                 goto nla_put_failure;
1674
1675         rtnh->rtnh_hops = nh_weight - 1;
1676         rtnh->rtnh_ifindex = dev ? dev->ifindex : 0;
1677
1678         if (fib_nexthop_info(skb, nhc, rt_family, &flags, true) < 0)
1679                 goto nla_put_failure;
1680
1681         rtnh->rtnh_flags = flags;
1682
1683         /* length of rtnetlink header + attributes */
1684         rtnh->rtnh_len = nlmsg_get_pos(skb) - (void *)rtnh;
1685
1686         return 0;
1687
1688 nla_put_failure:
1689         return -EMSGSIZE;
1690 }
1691 EXPORT_SYMBOL_GPL(fib_add_nexthop);
1692 #endif
1693
1694 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1695 static int fib_add_multipath(struct sk_buff *skb, struct fib_info *fi)
1696 {
1697         struct nlattr *mp;
1698
1699         mp = nla_nest_start_noflag(skb, RTA_MULTIPATH);
1700         if (!mp)
1701                 goto nla_put_failure;
1702
1703         if (unlikely(fi->nh)) {
1704                 if (nexthop_mpath_fill_node(skb, fi->nh, AF_INET) < 0)
1705                         goto nla_put_failure;
1706                 goto mp_end;
1707         }
1708
1709         for_nexthops(fi) {
1710                 if (fib_add_nexthop(skb, &nh->nh_common, nh->fib_nh_weight,
1711                                     AF_INET) < 0)
1712                         goto nla_put_failure;
1713 #ifdef CONFIG_IP_ROUTE_CLASSID
1714                 if (nh->nh_tclassid &&
1715                     nla_put_u32(skb, RTA_FLOW, nh->nh_tclassid))
1716                         goto nla_put_failure;
1717 #endif
1718         } endfor_nexthops(fi);
1719
1720 mp_end:
1721         nla_nest_end(skb, mp);
1722
1723         return 0;
1724
1725 nla_put_failure:
1726         return -EMSGSIZE;
1727 }
1728 #else
1729 static int fib_add_multipath(struct sk_buff *skb, struct fib_info *fi)
1730 {
1731         return 0;
1732 }
1733 #endif
1734
1735 int fib_dump_info(struct sk_buff *skb, u32 portid, u32 seq, int event,
1736                   struct fib_rt_info *fri, unsigned int flags)
1737 {
1738         unsigned int nhs = fib_info_num_path(fri->fi);
1739         struct fib_info *fi = fri->fi;
1740         u32 tb_id = fri->tb_id;
1741         struct nlmsghdr *nlh;
1742         struct rtmsg *rtm;
1743
1744         nlh = nlmsg_put(skb, portid, seq, event, sizeof(*rtm), flags);
1745         if (!nlh)
1746                 return -EMSGSIZE;
1747
1748         rtm = nlmsg_data(nlh);
1749         rtm->rtm_family = AF_INET;
1750         rtm->rtm_dst_len = fri->dst_len;
1751         rtm->rtm_src_len = 0;
1752         rtm->rtm_tos = fri->tos;
1753         if (tb_id < 256)
1754                 rtm->rtm_table = tb_id;
1755         else
1756                 rtm->rtm_table = RT_TABLE_COMPAT;
1757         if (nla_put_u32(skb, RTA_TABLE, tb_id))
1758                 goto nla_put_failure;
1759         rtm->rtm_type = fri->type;
1760         rtm->rtm_flags = fi->fib_flags;
1761         rtm->rtm_scope = fi->fib_scope;
1762         rtm->rtm_protocol = fi->fib_protocol;
1763
1764         if (rtm->rtm_dst_len &&
1765             nla_put_in_addr(skb, RTA_DST, fri->dst))
1766                 goto nla_put_failure;
1767         if (fi->fib_priority &&
1768             nla_put_u32(skb, RTA_PRIORITY, fi->fib_priority))
1769                 goto nla_put_failure;
1770         if (rtnetlink_put_metrics(skb, fi->fib_metrics->metrics) < 0)
1771                 goto nla_put_failure;
1772
1773         if (fi->fib_prefsrc &&
1774             nla_put_in_addr(skb, RTA_PREFSRC, fi->fib_prefsrc))
1775                 goto nla_put_failure;
1776
1777         if (fi->nh) {
1778                 if (nla_put_u32(skb, RTA_NH_ID, fi->nh->id))
1779                         goto nla_put_failure;
1780                 if (nexthop_is_blackhole(fi->nh))
1781                         rtm->rtm_type = RTN_BLACKHOLE;
1782                 if (!fi->fib_net->ipv4.sysctl_nexthop_compat_mode)
1783                         goto offload;
1784         }
1785
1786         if (nhs == 1) {
1787                 const struct fib_nh_common *nhc = fib_info_nhc(fi, 0);
1788                 unsigned char flags = 0;
1789
1790                 if (fib_nexthop_info(skb, nhc, AF_INET, &flags, false) < 0)
1791                         goto nla_put_failure;
1792
1793                 rtm->rtm_flags = flags;
1794 #ifdef CONFIG_IP_ROUTE_CLASSID
1795                 if (nhc->nhc_family == AF_INET) {
1796                         struct fib_nh *nh;
1797
1798                         nh = container_of(nhc, struct fib_nh, nh_common);
1799                         if (nh->nh_tclassid &&
1800                             nla_put_u32(skb, RTA_FLOW, nh->nh_tclassid))
1801                                 goto nla_put_failure;
1802                 }
1803 #endif
1804         } else {
1805                 if (fib_add_multipath(skb, fi) < 0)
1806                         goto nla_put_failure;
1807         }
1808
1809 offload:
1810         if (fri->offload)
1811                 rtm->rtm_flags |= RTM_F_OFFLOAD;
1812         if (fri->trap)
1813                 rtm->rtm_flags |= RTM_F_TRAP;
1814
1815         nlmsg_end(skb, nlh);
1816         return 0;
1817
1818 nla_put_failure:
1819         nlmsg_cancel(skb, nlh);
1820         return -EMSGSIZE;
1821 }
1822
1823 /*
1824  * Update FIB if:
1825  * - local address disappeared -> we must delete all the entries
1826  *   referring to it.
1827  * - device went down -> we must shutdown all nexthops going via it.
1828  */
1829 int fib_sync_down_addr(struct net_device *dev, __be32 local)
1830 {
1831         int ret = 0;
1832         unsigned int hash = fib_laddr_hashfn(local);
1833         struct hlist_head *head = &fib_info_laddrhash[hash];
1834         int tb_id = l3mdev_fib_table(dev) ? : RT_TABLE_MAIN;
1835         struct net *net = dev_net(dev);
1836         struct fib_info *fi;
1837
1838         if (!fib_info_laddrhash || local == 0)
1839                 return 0;
1840
1841         hlist_for_each_entry(fi, head, fib_lhash) {
1842                 if (!net_eq(fi->fib_net, net) ||
1843                     fi->fib_tb_id != tb_id)
1844                         continue;
1845                 if (fi->fib_prefsrc == local) {
1846                         fi->fib_flags |= RTNH_F_DEAD;
1847                         ret++;
1848                 }
1849         }
1850         return ret;
1851 }
1852
1853 static int call_fib_nh_notifiers(struct fib_nh *nh,
1854                                  enum fib_event_type event_type)
1855 {
1856         bool ignore_link_down = ip_ignore_linkdown(nh->fib_nh_dev);
1857         struct fib_nh_notifier_info info = {
1858                 .fib_nh = nh,
1859         };
1860
1861         switch (event_type) {
1862         case FIB_EVENT_NH_ADD:
1863                 if (nh->fib_nh_flags & RTNH_F_DEAD)
1864                         break;
1865                 if (ignore_link_down && nh->fib_nh_flags & RTNH_F_LINKDOWN)
1866                         break;
1867                 return call_fib4_notifiers(dev_net(nh->fib_nh_dev), event_type,
1868                                            &info.info);
1869         case FIB_EVENT_NH_DEL:
1870                 if ((ignore_link_down && nh->fib_nh_flags & RTNH_F_LINKDOWN) ||
1871                     (nh->fib_nh_flags & RTNH_F_DEAD))
1872                         return call_fib4_notifiers(dev_net(nh->fib_nh_dev),
1873                                                    event_type, &info.info);
1874         default:
1875                 break;
1876         }
1877
1878         return NOTIFY_DONE;
1879 }
1880
1881 /* Update the PMTU of exceptions when:
1882  * - the new MTU of the first hop becomes smaller than the PMTU
1883  * - the old MTU was the same as the PMTU, and it limited discovery of
1884  *   larger MTUs on the path. With that limit raised, we can now
1885  *   discover larger MTUs
1886  * A special case is locked exceptions, for which the PMTU is smaller
1887  * than the minimal accepted PMTU:
1888  * - if the new MTU is greater than the PMTU, don't make any change
1889  * - otherwise, unlock and set PMTU
1890  */
1891 void fib_nhc_update_mtu(struct fib_nh_common *nhc, u32 new, u32 orig)
1892 {
1893         struct fnhe_hash_bucket *bucket;
1894         int i;
1895
1896         bucket = rcu_dereference_protected(nhc->nhc_exceptions, 1);
1897         if (!bucket)
1898                 return;
1899
1900         for (i = 0; i < FNHE_HASH_SIZE; i++) {
1901                 struct fib_nh_exception *fnhe;
1902
1903                 for (fnhe = rcu_dereference_protected(bucket[i].chain, 1);
1904                      fnhe;
1905                      fnhe = rcu_dereference_protected(fnhe->fnhe_next, 1)) {
1906                         if (fnhe->fnhe_mtu_locked) {
1907                                 if (new <= fnhe->fnhe_pmtu) {
1908                                         fnhe->fnhe_pmtu = new;
1909                                         fnhe->fnhe_mtu_locked = false;
1910                                 }
1911                         } else if (new < fnhe->fnhe_pmtu ||
1912                                    orig == fnhe->fnhe_pmtu) {
1913                                 fnhe->fnhe_pmtu = new;
1914                         }
1915                 }
1916         }
1917 }
1918
1919 void fib_sync_mtu(struct net_device *dev, u32 orig_mtu)
1920 {
1921         unsigned int hash = fib_devindex_hashfn(dev->ifindex);
1922         struct hlist_head *head = &fib_info_devhash[hash];
1923         struct fib_nh *nh;
1924
1925         hlist_for_each_entry(nh, head, nh_hash) {
1926                 if (nh->fib_nh_dev == dev)
1927                         fib_nhc_update_mtu(&nh->nh_common, dev->mtu, orig_mtu);
1928         }
1929 }
1930
1931 /* Event              force Flags           Description
1932  * NETDEV_CHANGE      0     LINKDOWN        Carrier OFF, not for scope host
1933  * NETDEV_DOWN        0     LINKDOWN|DEAD   Link down, not for scope host
1934  * NETDEV_DOWN        1     LINKDOWN|DEAD   Last address removed
1935  * NETDEV_UNREGISTER  1     LINKDOWN|DEAD   Device removed
1936  *
1937  * only used when fib_nh is built into fib_info
1938  */
1939 int fib_sync_down_dev(struct net_device *dev, unsigned long event, bool force)
1940 {
1941         int ret = 0;
1942         int scope = RT_SCOPE_NOWHERE;
1943         struct fib_info *prev_fi = NULL;
1944         unsigned int hash = fib_devindex_hashfn(dev->ifindex);
1945         struct hlist_head *head = &fib_info_devhash[hash];
1946         struct fib_nh *nh;
1947
1948         if (force)
1949                 scope = -1;
1950
1951         hlist_for_each_entry(nh, head, nh_hash) {
1952                 struct fib_info *fi = nh->nh_parent;
1953                 int dead;
1954
1955                 BUG_ON(!fi->fib_nhs);
1956                 if (nh->fib_nh_dev != dev || fi == prev_fi)
1957                         continue;
1958                 prev_fi = fi;
1959                 dead = 0;
1960                 change_nexthops(fi) {
1961                         if (nexthop_nh->fib_nh_flags & RTNH_F_DEAD)
1962                                 dead++;
1963                         else if (nexthop_nh->fib_nh_dev == dev &&
1964                                  nexthop_nh->fib_nh_scope != scope) {
1965                                 switch (event) {
1966                                 case NETDEV_DOWN:
1967                                 case NETDEV_UNREGISTER:
1968                                         nexthop_nh->fib_nh_flags |= RTNH_F_DEAD;
1969                                         fallthrough;
1970                                 case NETDEV_CHANGE:
1971                                         nexthop_nh->fib_nh_flags |= RTNH_F_LINKDOWN;
1972                                         break;
1973                                 }
1974                                 call_fib_nh_notifiers(nexthop_nh,
1975                                                       FIB_EVENT_NH_DEL);
1976                                 dead++;
1977                         }
1978 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1979                         if (event == NETDEV_UNREGISTER &&
1980                             nexthop_nh->fib_nh_dev == dev) {
1981                                 dead = fi->fib_nhs;
1982                                 break;
1983                         }
1984 #endif
1985                 } endfor_nexthops(fi)
1986                 if (dead == fi->fib_nhs) {
1987                         switch (event) {
1988                         case NETDEV_DOWN:
1989                         case NETDEV_UNREGISTER:
1990                                 fi->fib_flags |= RTNH_F_DEAD;
1991                                 fallthrough;
1992                         case NETDEV_CHANGE:
1993                                 fi->fib_flags |= RTNH_F_LINKDOWN;
1994                                 break;
1995                         }
1996                         ret++;
1997                 }
1998
1999                 fib_rebalance(fi);
2000         }
2001
2002         return ret;
2003 }
2004
2005 /* Must be invoked inside of an RCU protected region.  */
2006 static void fib_select_default(const struct flowi4 *flp, struct fib_result *res)
2007 {
2008         struct fib_info *fi = NULL, *last_resort = NULL;
2009         struct hlist_head *fa_head = res->fa_head;
2010         struct fib_table *tb = res->table;
2011         u8 slen = 32 - res->prefixlen;
2012         int order = -1, last_idx = -1;
2013         struct fib_alias *fa, *fa1 = NULL;
2014         u32 last_prio = res->fi->fib_priority;
2015         u8 last_tos = 0;
2016
2017         hlist_for_each_entry_rcu(fa, fa_head, fa_list) {
2018                 struct fib_info *next_fi = fa->fa_info;
2019                 struct fib_nh_common *nhc;
2020
2021                 if (fa->fa_slen != slen)
2022                         continue;
2023                 if (fa->fa_tos && fa->fa_tos != flp->flowi4_tos)
2024                         continue;
2025                 if (fa->tb_id != tb->tb_id)
2026                         continue;
2027                 if (next_fi->fib_priority > last_prio &&
2028                     fa->fa_tos == last_tos) {
2029                         if (last_tos)
2030                                 continue;
2031                         break;
2032                 }
2033                 if (next_fi->fib_flags & RTNH_F_DEAD)
2034                         continue;
2035                 last_tos = fa->fa_tos;
2036                 last_prio = next_fi->fib_priority;
2037
2038                 if (next_fi->fib_scope != res->scope ||
2039                     fa->fa_type != RTN_UNICAST)
2040                         continue;
2041
2042                 nhc = fib_info_nhc(next_fi, 0);
2043                 if (!nhc->nhc_gw_family || nhc->nhc_scope != RT_SCOPE_LINK)
2044                         continue;
2045
2046                 fib_alias_accessed(fa);
2047
2048                 if (!fi) {
2049                         if (next_fi != res->fi)
2050                                 break;
2051                         fa1 = fa;
2052                 } else if (!fib_detect_death(fi, order, &last_resort,
2053                                              &last_idx, fa1->fa_default)) {
2054                         fib_result_assign(res, fi);
2055                         fa1->fa_default = order;
2056                         goto out;
2057                 }
2058                 fi = next_fi;
2059                 order++;
2060         }
2061
2062         if (order <= 0 || !fi) {
2063                 if (fa1)
2064                         fa1->fa_default = -1;
2065                 goto out;
2066         }
2067
2068         if (!fib_detect_death(fi, order, &last_resort, &last_idx,
2069                               fa1->fa_default)) {
2070                 fib_result_assign(res, fi);
2071                 fa1->fa_default = order;
2072                 goto out;
2073         }
2074
2075         if (last_idx >= 0)
2076                 fib_result_assign(res, last_resort);
2077         fa1->fa_default = last_idx;
2078 out:
2079         return;
2080 }
2081
2082 /*
2083  * Dead device goes up. We wake up dead nexthops.
2084  * It takes sense only on multipath routes.
2085  *
2086  * only used when fib_nh is built into fib_info
2087  */
2088 int fib_sync_up(struct net_device *dev, unsigned char nh_flags)
2089 {
2090         struct fib_info *prev_fi;
2091         unsigned int hash;
2092         struct hlist_head *head;
2093         struct fib_nh *nh;
2094         int ret;
2095
2096         if (!(dev->flags & IFF_UP))
2097                 return 0;
2098
2099         if (nh_flags & RTNH_F_DEAD) {
2100                 unsigned int flags = dev_get_flags(dev);
2101
2102                 if (flags & (IFF_RUNNING | IFF_LOWER_UP))
2103                         nh_flags |= RTNH_F_LINKDOWN;
2104         }
2105
2106         prev_fi = NULL;
2107         hash = fib_devindex_hashfn(dev->ifindex);
2108         head = &fib_info_devhash[hash];
2109         ret = 0;
2110
2111         hlist_for_each_entry(nh, head, nh_hash) {
2112                 struct fib_info *fi = nh->nh_parent;
2113                 int alive;
2114
2115                 BUG_ON(!fi->fib_nhs);
2116                 if (nh->fib_nh_dev != dev || fi == prev_fi)
2117                         continue;
2118
2119                 prev_fi = fi;
2120                 alive = 0;
2121                 change_nexthops(fi) {
2122                         if (!(nexthop_nh->fib_nh_flags & nh_flags)) {
2123                                 alive++;
2124                                 continue;
2125                         }
2126                         if (!nexthop_nh->fib_nh_dev ||
2127                             !(nexthop_nh->fib_nh_dev->flags & IFF_UP))
2128                                 continue;
2129                         if (nexthop_nh->fib_nh_dev != dev ||
2130                             !__in_dev_get_rtnl(dev))
2131                                 continue;
2132                         alive++;
2133                         nexthop_nh->fib_nh_flags &= ~nh_flags;
2134                         call_fib_nh_notifiers(nexthop_nh, FIB_EVENT_NH_ADD);
2135                 } endfor_nexthops(fi)
2136
2137                 if (alive > 0) {
2138                         fi->fib_flags &= ~nh_flags;
2139                         ret++;
2140                 }
2141
2142                 fib_rebalance(fi);
2143         }
2144
2145         return ret;
2146 }
2147
2148 #ifdef CONFIG_IP_ROUTE_MULTIPATH
2149 static bool fib_good_nh(const struct fib_nh *nh)
2150 {
2151         int state = NUD_REACHABLE;
2152
2153         if (nh->fib_nh_scope == RT_SCOPE_LINK) {
2154                 struct neighbour *n;
2155
2156                 rcu_read_lock_bh();
2157
2158                 if (likely(nh->fib_nh_gw_family == AF_INET))
2159                         n = __ipv4_neigh_lookup_noref(nh->fib_nh_dev,
2160                                                    (__force u32)nh->fib_nh_gw4);
2161                 else if (nh->fib_nh_gw_family == AF_INET6)
2162                         n = __ipv6_neigh_lookup_noref_stub(nh->fib_nh_dev,
2163                                                            &nh->fib_nh_gw6);
2164                 else
2165                         n = NULL;
2166                 if (n)
2167                         state = n->nud_state;
2168
2169                 rcu_read_unlock_bh();
2170         }
2171
2172         return !!(state & NUD_VALID);
2173 }
2174
2175 void fib_select_multipath(struct fib_result *res, int hash)
2176 {
2177         struct fib_info *fi = res->fi;
2178         struct net *net = fi->fib_net;
2179         bool first = false;
2180
2181         if (unlikely(res->fi->nh)) {
2182                 nexthop_path_fib_result(res, hash);
2183                 return;
2184         }
2185
2186         change_nexthops(fi) {
2187                 if (net->ipv4.sysctl_fib_multipath_use_neigh) {
2188                         if (!fib_good_nh(nexthop_nh))
2189                                 continue;
2190                         if (!first) {
2191                                 res->nh_sel = nhsel;
2192                                 res->nhc = &nexthop_nh->nh_common;
2193                                 first = true;
2194                         }
2195                 }
2196
2197                 if (hash > atomic_read(&nexthop_nh->fib_nh_upper_bound))
2198                         continue;
2199
2200                 res->nh_sel = nhsel;
2201                 res->nhc = &nexthop_nh->nh_common;
2202                 return;
2203         } endfor_nexthops(fi);
2204 }
2205 #endif
2206
2207 void fib_select_path(struct net *net, struct fib_result *res,
2208                      struct flowi4 *fl4, const struct sk_buff *skb)
2209 {
2210         if (fl4->flowi4_oif && !(fl4->flowi4_flags & FLOWI_FLAG_SKIP_NH_OIF))
2211                 goto check_saddr;
2212
2213 #ifdef CONFIG_IP_ROUTE_MULTIPATH
2214         if (fib_info_num_path(res->fi) > 1) {
2215                 int h = fib_multipath_hash(net, fl4, skb, NULL);
2216
2217                 fib_select_multipath(res, h);
2218         }
2219         else
2220 #endif
2221         if (!res->prefixlen &&
2222             res->table->tb_num_default > 1 &&
2223             res->type == RTN_UNICAST)
2224                 fib_select_default(fl4, res);
2225
2226 check_saddr:
2227         if (!fl4->saddr)
2228                 fl4->saddr = fib_result_prefsrc(net, res);
2229 }