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         dev_put(nhc->nhc_dev);
 212         lwtstate_put(nhc->nhc_lwtstate);
 213         rt_fibinfo_free_cpus(nhc->nhc_pcpu_rth_output);
 214         rt_fibinfo_free(&nhc->nhc_rth_input);
 215         free_nh_exceptions(nhc);
 216 }
 217 EXPORT_SYMBOL_GPL(fib_nh_common_release);
 218
 219 void fib_nh_release(struct net *net, struct fib_nh *fib_nh)
 220 {
 221 #ifdef CONFIG_IP_ROUTE_CLASSID
 222         if (fib_nh->nh_tclassid)
 223                 net->ipv4.fib_num_tclassid_users--;
 224 #endif
 225         fib_nh_common_release(&fib_nh->nh_common);
 226 }
 227
 228 /* Release a nexthop info record */
 229 static void free_fib_info_rcu(struct rcu_head *head)
 230 {
 231         struct fib_info *fi = container_of(head, struct fib_info, rcu);
 232
 233         if (fi->nh) {
 234                 nexthop_put(fi->nh);
 235         } else {
 236                 change_nexthops(fi) {
 237                         fib_nh_release(fi->fib_net, nexthop_nh);
 238                 } endfor_nexthops(fi);
 239         }
 240
 241         ip_fib_metrics_put(fi->fib_metrics);
 242
 243         kfree(fi);
 244 }
 245
 246 void free_fib_info(struct fib_info *fi)
 247 {
 248         if (fi->fib_dead == 0) {
 249                 pr_warn("Freeing alive fib_info %p\n", fi);
 250                 return;
 251         }
 252         fib_info_cnt--;
 253
 254         call_rcu(&fi->rcu, free_fib_info_rcu);
 255 }
 256 EXPORT_SYMBOL_GPL(free_fib_info);
 257
 258 void fib_release_info(struct fib_info *fi)
 259 {
 260         spin_lock_bh(&fib_info_lock);
 261         if (fi && refcount_dec_and_test(&fi->fib_treeref)) {
 262                 hlist_del(&fi->fib_hash);
 263                 if (fi->fib_prefsrc)
 264                         hlist_del(&fi->fib_lhash);
 265                 if (fi->nh) {
 266                         list_del(&fi->nh_list);
 267                 } else {
 268                         change_nexthops(fi) {
 269                                 if (!nexthop_nh->fib_nh_dev)
 270                                         continue;
 271                                 hlist_del(&nexthop_nh->nh_hash);
 272                         } endfor_nexthops(fi)
 273                 }
 274                 fi->fib_dead = 1;
 275                 fib_info_put(fi);
 276         }
 277         spin_unlock_bh(&fib_info_lock);
 278 }
 279
 280 static inline int nh_comp(struct fib_info *fi, struct fib_info *ofi)
 281 {
 282         const struct fib_nh *onh;
 283
 284         if (fi->nh || ofi->nh)
 285                 return nexthop_cmp(fi->nh, ofi->nh) ? 0 : -1;
 286
 287         if (ofi->fib_nhs == 0)
 288                 return 0;
 289
 290         for_nexthops(fi) {
 291                 onh = fib_info_nh(ofi, nhsel);
 292
 293                 if (nh->fib_nh_oif != onh->fib_nh_oif ||
 294                     nh->fib_nh_gw_family != onh->fib_nh_gw_family ||
 295                     nh->fib_nh_scope != onh->fib_nh_scope ||
 296 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 297                     nh->fib_nh_weight != onh->fib_nh_weight ||
 298 #endif
 299 #ifdef CONFIG_IP_ROUTE_CLASSID
 300                     nh->nh_tclassid != onh->nh_tclassid ||
 301 #endif
 302                     lwtunnel_cmp_encap(nh->fib_nh_lws, onh->fib_nh_lws) ||
 303                     ((nh->fib_nh_flags ^ onh->fib_nh_flags) & ~RTNH_COMPARE_MASK))
 304                         return -1;
 305
 306                 if (nh->fib_nh_gw_family == AF_INET &&
 307                     nh->fib_nh_gw4 != onh->fib_nh_gw4)
 308                         return -1;
 309
 310                 if (nh->fib_nh_gw_family == AF_INET6 &&
 311                     ipv6_addr_cmp(&nh->fib_nh_gw6, &onh->fib_nh_gw6))
 312                         return -1;
 313         } endfor_nexthops(fi);
 314         return 0;
 315 }
 316
 317 static inline unsigned int fib_devindex_hashfn(unsigned int val)
 318 {
 319         unsigned int mask = DEVINDEX_HASHSIZE - 1;
 320
 321         return (val ^
 322                 (val >> DEVINDEX_HASHBITS) ^
 323                 (val >> (DEVINDEX_HASHBITS * 2))) & mask;
 324 }
 325
 326 static unsigned int fib_info_hashfn_1(int init_val, u8 protocol, u8 scope,
 327                                       u32 prefsrc, u32 priority)
 328 {
 329         unsigned int val = init_val;
 330
 331         val ^= (protocol << 8) | scope;
 332         val ^= prefsrc;
 333         val ^= priority;
 334
 335         return val;
 336 }
 337
 338 static unsigned int fib_info_hashfn_result(unsigned int val)
 339 {
 340         unsigned int mask = (fib_info_hash_size - 1);
 341
 342         return (val ^ (val >> 7) ^ (val >> 12)) & mask;
 343 }
 344
 345 static inline unsigned int fib_info_hashfn(struct fib_info *fi)
 346 {
 347         unsigned int val;
 348
 349         val = fib_info_hashfn_1(fi->fib_nhs, fi->fib_protocol,
 350                                 fi->fib_scope, (__force u32)fi->fib_prefsrc,
 351                                 fi->fib_priority);
 352
 353         if (fi->nh) {
 354                 val ^= fib_devindex_hashfn(fi->nh->id);
 355         } else {
 356                 for_nexthops(fi) {
 357                         val ^= fib_devindex_hashfn(nh->fib_nh_oif);
 358                 } endfor_nexthops(fi)
 359         }
 360
 361         return fib_info_hashfn_result(val);
 362 }
 363
 364 /* no metrics, only nexthop id */
 365 static struct fib_info *fib_find_info_nh(struct net *net,
 366                                          const struct fib_config *cfg)
 367 {
 368         struct hlist_head *head;
 369         struct fib_info *fi;
 370         unsigned int hash;
 371
 372         hash = fib_info_hashfn_1(fib_devindex_hashfn(cfg->fc_nh_id),
 373                                  cfg->fc_protocol, cfg->fc_scope,
 374                                  (__force u32)cfg->fc_prefsrc,
 375                                  cfg->fc_priority);
 376         hash = fib_info_hashfn_result(hash);
 377         head = &fib_info_hash[hash];
 378
 379         hlist_for_each_entry(fi, head, fib_hash) {
 380                 if (!net_eq(fi->fib_net, net))
 381                         continue;
 382                 if (!fi->nh || fi->nh->id != cfg->fc_nh_id)
 383                         continue;
 384                 if (cfg->fc_protocol == fi->fib_protocol &&
 385                     cfg->fc_scope == fi->fib_scope &&
 386                     cfg->fc_prefsrc == fi->fib_prefsrc &&
 387                     cfg->fc_priority == fi->fib_priority &&
 388                     cfg->fc_type == fi->fib_type &&
 389                     cfg->fc_table == fi->fib_tb_id &&
 390                     !((cfg->fc_flags ^ fi->fib_flags) & ~RTNH_COMPARE_MASK))
 391                         return fi;
 392         }
 393
 394         return NULL;
 395 }
 396
 397 static struct fib_info *fib_find_info(struct fib_info *nfi)
 398 {
 399         struct hlist_head *head;
 400         struct fib_info *fi;
 401         unsigned int hash;
 402
 403         hash = fib_info_hashfn(nfi);
 404         head = &fib_info_hash[hash];
 405
 406         hlist_for_each_entry(fi, head, fib_hash) {
 407                 if (!net_eq(fi->fib_net, nfi->fib_net))
 408                         continue;
 409                 if (fi->fib_nhs != nfi->fib_nhs)
 410                         continue;
 411                 if (nfi->fib_protocol == fi->fib_protocol &&
 412                     nfi->fib_scope == fi->fib_scope &&
 413                     nfi->fib_prefsrc == fi->fib_prefsrc &&
 414                     nfi->fib_priority == fi->fib_priority &&
 415                     nfi->fib_type == fi->fib_type &&
 416                     memcmp(nfi->fib_metrics, fi->fib_metrics,
 417                            sizeof(u32) * RTAX_MAX) == 0 &&
 418                     !((nfi->fib_flags ^ fi->fib_flags) & ~RTNH_COMPARE_MASK) &&
 419                     nh_comp(fi, nfi) == 0)
 420                         return fi;
 421         }
 422
 423         return NULL;
 424 }
 425
 426 /* Check, that the gateway is already configured.
 427  * Used only by redirect accept routine.
 428  */
 429 int ip_fib_check_default(__be32 gw, struct net_device *dev)
 430 {
 431         struct hlist_head *head;
 432         struct fib_nh *nh;
 433         unsigned int hash;
 434
 435         spin_lock(&fib_info_lock);
 436
 437         hash = fib_devindex_hashfn(dev->ifindex);
 438         head = &fib_info_devhash[hash];
 439         hlist_for_each_entry(nh, head, nh_hash) {
 440                 if (nh->fib_nh_dev == dev &&
 441                     nh->fib_nh_gw4 == gw &&
 442                     !(nh->fib_nh_flags & RTNH_F_DEAD)) {
 443                         spin_unlock(&fib_info_lock);
 444                         return 0;
 445                 }
 446         }
 447
 448         spin_unlock(&fib_info_lock);
 449
 450         return -1;
 451 }
 452
 453 size_t fib_nlmsg_size(struct fib_info *fi)
 454 {
 455         size_t payload = NLMSG_ALIGN(sizeof(struct rtmsg))
 456                          + nla_total_size(4) /* RTA_TABLE */
 457                          + nla_total_size(4) /* RTA_DST */
 458                          + nla_total_size(4) /* RTA_PRIORITY */
 459                          + nla_total_size(4) /* RTA_PREFSRC */
 460                          + nla_total_size(TCP_CA_NAME_MAX); /* RTAX_CC_ALGO */
 461         unsigned int nhs = fib_info_num_path(fi);
 462
 463         /* space for nested metrics */
 464         payload += nla_total_size((RTAX_MAX * nla_total_size(4)));
 465
 466         if (fi->nh)
 467                 payload += nla_total_size(4); /* RTA_NH_ID */
 468
 469         if (nhs) {
 470                 size_t nh_encapsize = 0;
 471                 /* Also handles the special case nhs == 1 */
 472
 473                 /* each nexthop is packed in an attribute */
 474                 size_t nhsize = nla_total_size(sizeof(struct rtnexthop));
 475                 unsigned int i;
 476
 477                 /* may contain flow and gateway attribute */
 478                 nhsize += 2 * nla_total_size(4);
 479
 480                 /* grab encap info */
 481                 for (i = 0; i < fib_info_num_path(fi); i++) {
 482                         struct fib_nh_common *nhc = fib_info_nhc(fi, i);
 483
 484                         if (nhc->nhc_lwtstate) {
 485                                 /* RTA_ENCAP_TYPE */
 486                                 nh_encapsize += lwtunnel_get_encap_size(
 487                                                 nhc->nhc_lwtstate);
 488                                 /* RTA_ENCAP */
 489                                 nh_encapsize +=  nla_total_size(2);
 490                         }
 491                 }
 492
 493                 /* all nexthops are packed in a nested attribute */
 494                 payload += nla_total_size((nhs * nhsize) + nh_encapsize);
 495
 496         }
 497
 498         return payload;
 499 }
 500
 501 void rtmsg_fib(int event, __be32 key, struct fib_alias *fa,
 502                int dst_len, u32 tb_id, const struct nl_info *info,
 503                unsigned int nlm_flags)
 504 {
 505         struct fib_rt_info fri;
 506         struct sk_buff *skb;
 507         u32 seq = info->nlh ? info->nlh->nlmsg_seq : 0;
 508         int err = -ENOBUFS;
 509
 510         skb = nlmsg_new(fib_nlmsg_size(fa->fa_info), GFP_KERNEL);
 511         if (!skb)
 512                 goto errout;
 513
 514         fri.fi = fa->fa_info;
 515         fri.tb_id = tb_id;
 516         fri.dst = key;
 517         fri.dst_len = dst_len;
 518         fri.tos = fa->fa_tos;
 519         fri.type = fa->fa_type;
 520         fri.offload = fa->offload;
 521         fri.trap = fa->trap;
 522         fri.offload_failed = fa->offload_failed;
 523         err = fib_dump_info(skb, info->portid, seq, event, &fri, nlm_flags);
 524         if (err < 0) {
 525                 /* -EMSGSIZE implies BUG in fib_nlmsg_size() */
 526                 WARN_ON(err == -EMSGSIZE);
 527                 kfree_skb(skb);
 528                 goto errout;
 529         }
 530         rtnl_notify(skb, info->nl_net, info->portid, RTNLGRP_IPV4_ROUTE,
 531                     info->nlh, GFP_KERNEL);
 532         return;
 533 errout:
 534         if (err < 0)
 535                 rtnl_set_sk_err(info->nl_net, RTNLGRP_IPV4_ROUTE, err);
 536 }
 537
 538 static int fib_detect_death(struct fib_info *fi, int order,
 539                             struct fib_info **last_resort, int *last_idx,
 540                             int dflt)
 541 {
 542         const struct fib_nh_common *nhc = fib_info_nhc(fi, 0);
 543         struct neighbour *n;
 544         int state = NUD_NONE;
 545
 546         if (likely(nhc->nhc_gw_family == AF_INET))
 547                 n = neigh_lookup(&arp_tbl, &nhc->nhc_gw.ipv4, nhc->nhc_dev);
 548         else if (nhc->nhc_gw_family == AF_INET6)
 549                 n = neigh_lookup(ipv6_stub->nd_tbl, &nhc->nhc_gw.ipv6,
 550                                  nhc->nhc_dev);
 551         else
 552                 n = NULL;
 553
 554         if (n) {
 555                 state = n->nud_state;
 556                 neigh_release(n);
 557         } else {
 558                 return 0;
 559         }
 560         if (state == NUD_REACHABLE)
 561                 return 0;
 562         if ((state & NUD_VALID) && order != dflt)
 563                 return 0;
 564         if ((state & NUD_VALID) ||
 565             (*last_idx < 0 && order > dflt && state != NUD_INCOMPLETE)) {
 566                 *last_resort = fi;
 567                 *last_idx = order;
 568         }
 569         return 1;
 570 }
 571
 572 int fib_nh_common_init(struct net *net, struct fib_nh_common *nhc,
 573                        struct nlattr *encap, u16 encap_type,
 574                        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(net, encap_type, encap,
 593                                            nhc->nhc_family, cfg, &lwtstate,
 594                                            extack);
 595                 if (err)
 596                         goto lwt_failure;
 597
 598                 nhc->nhc_lwtstate = lwtstate_get(lwtstate);
 599         }
 600
 601         return 0;
 602
 603 lwt_failure:
 604         rt_fibinfo_free_cpus(nhc->nhc_pcpu_rth_output);
 605         nhc->nhc_pcpu_rth_output = NULL;
 606         return err;
 607 }
 608 EXPORT_SYMBOL_GPL(fib_nh_common_init);
 609
 610 int fib_nh_init(struct net *net, struct fib_nh *nh,
 611                 struct fib_config *cfg, int nh_weight,
 612                 struct netlink_ext_ack *extack)
 613 {
 614         int err;
 615
 616         nh->fib_nh_family = AF_INET;
 617
 618         err = fib_nh_common_init(net, &nh->nh_common, cfg->fc_encap,
 619                                  cfg->fc_encap_type, cfg, GFP_KERNEL, extack);
 620         if (err)
 621                 return err;
 622
 623         nh->fib_nh_oif = cfg->fc_oif;
 624         nh->fib_nh_gw_family = cfg->fc_gw_family;
 625         if (cfg->fc_gw_family == AF_INET)
 626                 nh->fib_nh_gw4 = cfg->fc_gw4;
 627         else if (cfg->fc_gw_family == AF_INET6)
 628                 nh->fib_nh_gw6 = cfg->fc_gw6;
 629
 630         nh->fib_nh_flags = cfg->fc_flags;
 631
 632 #ifdef CONFIG_IP_ROUTE_CLASSID
 633         nh->nh_tclassid = cfg->fc_flow;
 634         if (nh->nh_tclassid)
 635                 net->ipv4.fib_num_tclassid_users++;
 636 #endif
 637 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 638         nh->fib_nh_weight = nh_weight;
 639 #endif
 640         return 0;
 641 }
 642
 643 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 644
 645 static int fib_count_nexthops(struct rtnexthop *rtnh, int remaining,
 646                               struct netlink_ext_ack *extack)
 647 {
 648         int nhs = 0;
 649
 650         while (rtnh_ok(rtnh, remaining)) {
 651                 nhs++;
 652                 rtnh = rtnh_next(rtnh, &remaining);
 653         }
 654
 655         /* leftover implies invalid nexthop configuration, discard it */
 656         if (remaining > 0) {
 657                 NL_SET_ERR_MSG(extack,
 658                                "Invalid nexthop configuration - extra data after nexthops");
 659                 nhs = 0;
 660         }
 661
 662         return nhs;
 663 }
 664
 665 /* only called when fib_nh is integrated into fib_info */
 666 static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh,
 667                        int remaining, struct fib_config *cfg,
 668                        struct netlink_ext_ack *extack)
 669 {
 670         struct net *net = fi->fib_net;
 671         struct fib_config fib_cfg;
 672         struct fib_nh *nh;
 673         int ret;
 674
 675         change_nexthops(fi) {
 676                 int attrlen;
 677
 678                 memset(&fib_cfg, 0, sizeof(fib_cfg));
 679
 680                 if (!rtnh_ok(rtnh, remaining)) {
 681                         NL_SET_ERR_MSG(extack,
 682                                        "Invalid nexthop configuration - extra data after nexthop");
 683                         return -EINVAL;
 684                 }
 685
 686                 if (rtnh->rtnh_flags & (RTNH_F_DEAD | RTNH_F_LINKDOWN)) {
 687                         NL_SET_ERR_MSG(extack,
 688                                        "Invalid flags for nexthop - can not contain DEAD or LINKDOWN");
 689                         return -EINVAL;
 690                 }
 691
 692                 fib_cfg.fc_flags = (cfg->fc_flags & ~0xFF) | rtnh->rtnh_flags;
 693                 fib_cfg.fc_oif = rtnh->rtnh_ifindex;
 694
 695                 attrlen = rtnh_attrlen(rtnh);
 696                 if (attrlen > 0) {
 697                         struct nlattr *nla, *nlav, *attrs = rtnh_attrs(rtnh);
 698
 699                         nla = nla_find(attrs, attrlen, RTA_GATEWAY);
 700                         nlav = nla_find(attrs, attrlen, RTA_VIA);
 701                         if (nla && nlav) {
 702                                 NL_SET_ERR_MSG(extack,
 703                                                "Nexthop configuration can not contain both GATEWAY and VIA");
 704                                 return -EINVAL;
 705                         }
 706                         if (nla) {
 707                                 fib_cfg.fc_gw4 = nla_get_in_addr(nla);
 708                                 if (fib_cfg.fc_gw4)
 709                                         fib_cfg.fc_gw_family = AF_INET;
 710                         } else if (nlav) {
 711                                 ret = fib_gw_from_via(&fib_cfg, nlav, extack);
 712                                 if (ret)
 713                                         goto errout;
 714                         }
 715
 716                         nla = nla_find(attrs, attrlen, RTA_FLOW);
 717                         if (nla)
 718                                 fib_cfg.fc_flow = nla_get_u32(nla);
 719
 720                         fib_cfg.fc_encap = nla_find(attrs, attrlen, RTA_ENCAP);
 721                         nla = nla_find(attrs, attrlen, RTA_ENCAP_TYPE);
 722                         if (nla)
 723                                 fib_cfg.fc_encap_type = nla_get_u16(nla);
 724                 }
 725
 726                 ret = fib_nh_init(net, nexthop_nh, &fib_cfg,
 727                                   rtnh->rtnh_hops + 1, extack);
 728                 if (ret)
 729                         goto errout;
 730
 731                 rtnh = rtnh_next(rtnh, &remaining);
 732         } endfor_nexthops(fi);
 733
 734         ret = -EINVAL;
 735         nh = fib_info_nh(fi, 0);
 736         if (cfg->fc_oif && nh->fib_nh_oif != cfg->fc_oif) {
 737                 NL_SET_ERR_MSG(extack,
 738                                "Nexthop device index does not match RTA_OIF");
 739                 goto errout;
 740         }
 741         if (cfg->fc_gw_family) {
 742                 if (cfg->fc_gw_family != nh->fib_nh_gw_family ||
 743                     (cfg->fc_gw_family == AF_INET &&
 744                      nh->fib_nh_gw4 != cfg->fc_gw4) ||
 745                     (cfg->fc_gw_family == AF_INET6 &&
 746                      ipv6_addr_cmp(&nh->fib_nh_gw6, &cfg->fc_gw6))) {
 747                         NL_SET_ERR_MSG(extack,
 748                                        "Nexthop gateway does not match RTA_GATEWAY or RTA_VIA");
 749                         goto errout;
 750                 }
 751         }
 752 #ifdef CONFIG_IP_ROUTE_CLASSID
 753         if (cfg->fc_flow && nh->nh_tclassid != cfg->fc_flow) {
 754                 NL_SET_ERR_MSG(extack,
 755                                "Nexthop class id does not match RTA_FLOW");
 756                 goto errout;
 757         }
 758 #endif
 759         ret = 0;
 760 errout:
 761         return ret;
 762 }
 763
 764 /* only called when fib_nh is integrated into fib_info */
 765 static void fib_rebalance(struct fib_info *fi)
 766 {
 767         int total;
 768         int w;
 769
 770         if (fib_info_num_path(fi) < 2)
 771                 return;
 772
 773         total = 0;
 774         for_nexthops(fi) {
 775                 if (nh->fib_nh_flags & RTNH_F_DEAD)
 776                         continue;
 777
 778                 if (ip_ignore_linkdown(nh->fib_nh_dev) &&
 779                     nh->fib_nh_flags & RTNH_F_LINKDOWN)
 780                         continue;
 781
 782                 total += nh->fib_nh_weight;
 783         } endfor_nexthops(fi);
 784
 785         w = 0;
 786         change_nexthops(fi) {
 787                 int upper_bound;
 788
 789                 if (nexthop_nh->fib_nh_flags & RTNH_F_DEAD) {
 790                         upper_bound = -1;
 791                 } else if (ip_ignore_linkdown(nexthop_nh->fib_nh_dev) &&
 792                            nexthop_nh->fib_nh_flags & RTNH_F_LINKDOWN) {
 793                         upper_bound = -1;
 794                 } else {
 795                         w += nexthop_nh->fib_nh_weight;
 796                         upper_bound = DIV_ROUND_CLOSEST_ULL((u64)w << 31,
 797                                                             total) - 1;
 798                 }
 799
 800                 atomic_set(&nexthop_nh->fib_nh_upper_bound, upper_bound);
 801         } endfor_nexthops(fi);
 802 }
 803 #else /* CONFIG_IP_ROUTE_MULTIPATH */
 804
 805 static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh,
 806                        int remaining, struct fib_config *cfg,
 807                        struct netlink_ext_ack *extack)
 808 {
 809         NL_SET_ERR_MSG(extack, "Multipath support not enabled in kernel");
 810
 811         return -EINVAL;
 812 }
 813
 814 #define fib_rebalance(fi) do { } while (0)
 815
 816 #endif /* CONFIG_IP_ROUTE_MULTIPATH */
 817
 818 static int fib_encap_match(struct net *net, u16 encap_type,
 819                            struct nlattr *encap,
 820                            const struct fib_nh *nh,
 821                            const struct fib_config *cfg,
 822                            struct netlink_ext_ack *extack)
 823 {
 824         struct lwtunnel_state *lwtstate;
 825         int ret, result = 0;
 826
 827         if (encap_type == LWTUNNEL_ENCAP_NONE)
 828                 return 0;
 829
 830         ret = lwtunnel_build_state(net, encap_type, encap, AF_INET,
 831                                    cfg, &lwtstate, extack);
 832         if (!ret) {
 833                 result = lwtunnel_cmp_encap(lwtstate, nh->fib_nh_lws);
 834                 lwtstate_free(lwtstate);
 835         }
 836
 837         return result;
 838 }
 839
 840 int fib_nh_match(struct net *net, struct fib_config *cfg, struct fib_info *fi,
 841                  struct netlink_ext_ack *extack)
 842 {
 843 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 844         struct rtnexthop *rtnh;
 845         int remaining;
 846 #endif
 847
 848         if (cfg->fc_priority && cfg->fc_priority != fi->fib_priority)
 849                 return 1;
 850
 851         if (cfg->fc_nh_id) {
 852                 if (fi->nh && cfg->fc_nh_id == fi->nh->id)
 853                         return 0;
 854                 return 1;
 855         }
 856
 857         if (cfg->fc_oif || cfg->fc_gw_family) {
 858                 struct fib_nh *nh = fib_info_nh(fi, 0);
 859
 860                 if (cfg->fc_encap) {
 861                         if (fib_encap_match(net, cfg->fc_encap_type,
 862                                             cfg->fc_encap, nh, cfg, extack))
 863                                 return 1;
 864                 }
 865 #ifdef CONFIG_IP_ROUTE_CLASSID
 866                 if (cfg->fc_flow &&
 867                     cfg->fc_flow != nh->nh_tclassid)
 868                         return 1;
 869 #endif
 870                 if ((cfg->fc_oif && cfg->fc_oif != nh->fib_nh_oif) ||
 871                     (cfg->fc_gw_family &&
 872                      cfg->fc_gw_family != nh->fib_nh_gw_family))
 873                         return 1;
 874
 875                 if (cfg->fc_gw_family == AF_INET &&
 876                     cfg->fc_gw4 != nh->fib_nh_gw4)
 877                         return 1;
 878
 879                 if (cfg->fc_gw_family == AF_INET6 &&
 880                     ipv6_addr_cmp(&cfg->fc_gw6, &nh->fib_nh_gw6))
 881                         return 1;
 882
 883                 return 0;
 884         }
 885
 886 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 887         if (!cfg->fc_mp)
 888                 return 0;
 889
 890         rtnh = cfg->fc_mp;
 891         remaining = cfg->fc_mp_len;
 892
 893         for_nexthops(fi) {
 894                 int attrlen;
 895
 896                 if (!rtnh_ok(rtnh, remaining))
 897                         return -EINVAL;
 898
 899                 if (rtnh->rtnh_ifindex && rtnh->rtnh_ifindex != nh->fib_nh_oif)
 900                         return 1;
 901
 902                 attrlen = rtnh_attrlen(rtnh);
 903                 if (attrlen > 0) {
 904                         struct nlattr *nla, *nlav, *attrs = rtnh_attrs(rtnh);
 905
 906                         nla = nla_find(attrs, attrlen, RTA_GATEWAY);
 907                         nlav = nla_find(attrs, attrlen, RTA_VIA);
 908                         if (nla && nlav) {
 909                                 NL_SET_ERR_MSG(extack,
 910                                                "Nexthop configuration can not contain both GATEWAY and VIA");
 911                                 return -EINVAL;
 912                         }
 913
 914                         if (nla) {
 915                                 if (nh->fib_nh_gw_family != AF_INET ||
 916                                     nla_get_in_addr(nla) != nh->fib_nh_gw4)
 917                                         return 1;
 918                         } else if (nlav) {
 919                                 struct fib_config cfg2;
 920                                 int err;
 921
 922                                 err = fib_gw_from_via(&cfg2, nlav, extack);
 923                                 if (err)
 924                                         return err;
 925
 926                                 switch (nh->fib_nh_gw_family) {
 927                                 case AF_INET:
 928                                         if (cfg2.fc_gw_family != AF_INET ||
 929                                             cfg2.fc_gw4 != nh->fib_nh_gw4)
 930                                                 return 1;
 931                                         break;
 932                                 case AF_INET6:
 933                                         if (cfg2.fc_gw_family != AF_INET6 ||
 934                                             ipv6_addr_cmp(&cfg2.fc_gw6,
 935                                                           &nh->fib_nh_gw6))
 936                                                 return 1;
 937                                         break;
 938                                 }
 939                         }
 940
 941 #ifdef CONFIG_IP_ROUTE_CLASSID
 942                         nla = nla_find(attrs, attrlen, RTA_FLOW);
 943                         if (nla && nla_get_u32(nla) != nh->nh_tclassid)
 944                                 return 1;
 945 #endif
 946                 }
 947
 948                 rtnh = rtnh_next(rtnh, &remaining);
 949         } endfor_nexthops(fi);
 950 #endif
 951         return 0;
 952 }
 953
 954 bool fib_metrics_match(struct fib_config *cfg, struct fib_info *fi)
 955 {
 956         struct nlattr *nla;
 957         int remaining;
 958
 959         if (!cfg->fc_mx)
 960                 return true;
 961
 962         nla_for_each_attr(nla, cfg->fc_mx, cfg->fc_mx_len, remaining) {
 963                 int type = nla_type(nla);
 964                 u32 fi_val, val;
 965
 966                 if (!type)
 967                         continue;
 968                 if (type > RTAX_MAX)
 969                         return false;
 970
 971                 if (type == RTAX_CC_ALGO) {
 972                         char tmp[TCP_CA_NAME_MAX];
 973                         bool ecn_ca = false;
 974
 975                         nla_strscpy(tmp, nla, sizeof(tmp));
 976                         val = tcp_ca_get_key_by_name(fi->fib_net, tmp, &ecn_ca);
 977                 } else {
 978                         if (nla_len(nla) != sizeof(u32))
 979                                 return false;
 980                         val = nla_get_u32(nla);
 981                 }
 982
 983                 fi_val = fi->fib_metrics->metrics[type - 1];
 984                 if (type == RTAX_FEATURES)
 985                         fi_val &= ~DST_FEATURE_ECN_CA;
 986
 987                 if (fi_val != val)
 988                         return false;
 989         }
 990
 991         return true;
 992 }
 993
 994 static int fib_check_nh_v6_gw(struct net *net, struct fib_nh *nh,
 995                               u32 table, struct netlink_ext_ack *extack)
 996 {
 997         struct fib6_config cfg = {
 998                 .fc_table = table,
 999                 .fc_flags = nh->fib_nh_flags | RTF_GATEWAY,
1000                 .fc_ifindex = nh->fib_nh_oif,
1001                 .fc_gateway = nh->fib_nh_gw6,
1002         };
1003         struct fib6_nh fib6_nh = {};
1004         int err;
1005
1006         err = ipv6_stub->fib6_nh_init(net, &fib6_nh, &cfg, GFP_KERNEL, extack);
1007         if (!err) {
1008                 nh->fib_nh_dev = fib6_nh.fib_nh_dev;
1009                 dev_hold(nh->fib_nh_dev);
1010                 nh->fib_nh_oif = nh->fib_nh_dev->ifindex;
1011                 nh->fib_nh_scope = RT_SCOPE_LINK;
1012
1013                 ipv6_stub->fib6_nh_release(&fib6_nh);
1014         }
1015
1016         return err;
1017 }
1018
1019 /*
1020  * Picture
1021  * -------
1022  *
1023  * Semantics of nexthop is very messy by historical reasons.
1024  * We have to take into account, that:
1025  * a) gateway can be actually local interface address,
1026  *    so that gatewayed route is direct.
1027  * b) gateway must be on-link address, possibly
1028  *    described not by an ifaddr, but also by a direct route.
1029  * c) If both gateway and interface are specified, they should not
1030  *    contradict.
1031  * d) If we use tunnel routes, gateway could be not on-link.
1032  *
1033  * Attempt to reconcile all of these (alas, self-contradictory) conditions
1034  * results in pretty ugly and hairy code with obscure logic.
1035  *
1036  * I chose to generalized it instead, so that the size
1037  * of code does not increase practically, but it becomes
1038  * much more general.
1039  * Every prefix is assigned a "scope" value: "host" is local address,
1040  * "link" is direct route,
1041  * [ ... "site" ... "interior" ... ]
1042  * and "universe" is true gateway route with global meaning.
1043  *
1044  * Every prefix refers to a set of "nexthop"s (gw, oif),
1045  * where gw must have narrower scope. This recursion stops
1046  * when gw has LOCAL scope or if "nexthop" is declared ONLINK,
1047  * which means that gw is forced to be on link.
1048  *
1049  * Code is still hairy, but now it is apparently logically
1050  * consistent and very flexible. F.e. as by-product it allows
1051  * to co-exists in peace independent exterior and interior
1052  * routing processes.
1053  *
1054  * Normally it looks as following.
1055  *
1056  * {universe prefix}  -> (gw, oif) [scope link]
1057  *                |
1058  *                |-> {link prefix} -> (gw, oif) [scope local]
1059  *                                      |
1060  *                                      |-> {local prefix} (terminal node)
1061  */
1062 static int fib_check_nh_v4_gw(struct net *net, struct fib_nh *nh, u32 table,
1063                               u8 scope, struct netlink_ext_ack *extack)
1064 {
1065         struct net_device *dev;
1066         struct fib_result res;
1067         int err = 0;
1068
1069         if (nh->fib_nh_flags & RTNH_F_ONLINK) {
1070                 unsigned int addr_type;
1071
1072                 if (scope >= RT_SCOPE_LINK) {
1073                         NL_SET_ERR_MSG(extack, "Nexthop has invalid scope");
1074                         return -EINVAL;
1075                 }
1076                 dev = __dev_get_by_index(net, nh->fib_nh_oif);
1077                 if (!dev) {
1078                         NL_SET_ERR_MSG(extack, "Nexthop device required for onlink");
1079                         return -ENODEV;
1080                 }
1081                 if (!(dev->flags & IFF_UP)) {
1082                         NL_SET_ERR_MSG(extack, "Nexthop device is not up");
1083                         return -ENETDOWN;
1084                 }
1085                 addr_type = inet_addr_type_dev_table(net, dev, nh->fib_nh_gw4);
1086                 if (addr_type != RTN_UNICAST) {
1087                         NL_SET_ERR_MSG(extack, "Nexthop has invalid gateway");
1088                         return -EINVAL;
1089                 }
1090                 if (!netif_carrier_ok(dev))
1091                         nh->fib_nh_flags |= RTNH_F_LINKDOWN;
1092                 nh->fib_nh_dev = dev;
1093                 dev_hold(dev);
1094                 nh->fib_nh_scope = RT_SCOPE_LINK;
1095                 return 0;
1096         }
1097         rcu_read_lock();
1098         {
1099                 struct fib_table *tbl = NULL;
1100                 struct flowi4 fl4 = {
1101                         .daddr = nh->fib_nh_gw4,
1102                         .flowi4_scope = scope + 1,
1103                         .flowi4_oif = nh->fib_nh_oif,
1104                         .flowi4_iif = LOOPBACK_IFINDEX,
1105                 };
1106
1107                 /* It is not necessary, but requires a bit of thinking */
1108                 if (fl4.flowi4_scope < RT_SCOPE_LINK)
1109                         fl4.flowi4_scope = RT_SCOPE_LINK;
1110
1111                 if (table && table != RT_TABLE_MAIN)
1112                         tbl = fib_get_table(net, table);
1113
1114                 if (tbl)
1115                         err = fib_table_lookup(tbl, &fl4, &res,
1116                                                FIB_LOOKUP_IGNORE_LINKSTATE |
1117                                                FIB_LOOKUP_NOREF);
1118
1119                 /* on error or if no table given do full lookup. This
1120                  * is needed for example when nexthops are in the local
1121                  * table rather than the given table
1122                  */
1123                 if (!tbl || err) {
1124                         err = fib_lookup(net, &fl4, &res,
1125                                          FIB_LOOKUP_IGNORE_LINKSTATE);
1126                 }
1127
1128                 if (err) {
1129                         NL_SET_ERR_MSG(extack, "Nexthop has invalid gateway");
1130                         goto out;
1131                 }
1132         }
1133
1134         err = -EINVAL;
1135         if (res.type != RTN_UNICAST && res.type != RTN_LOCAL) {
1136                 NL_SET_ERR_MSG(extack, "Nexthop has invalid gateway");
1137                 goto out;
1138         }
1139         nh->fib_nh_scope = res.scope;
1140         nh->fib_nh_oif = FIB_RES_OIF(res);
1141         nh->fib_nh_dev = dev = FIB_RES_DEV(res);
1142         if (!dev) {
1143                 NL_SET_ERR_MSG(extack,
1144                                "No egress device for nexthop gateway");
1145                 goto out;
1146         }
1147         dev_hold(dev);
1148         if (!netif_carrier_ok(dev))
1149                 nh->fib_nh_flags |= RTNH_F_LINKDOWN;
1150         err = (dev->flags & IFF_UP) ? 0 : -ENETDOWN;
1151 out:
1152         rcu_read_unlock();
1153         return err;
1154 }
1155
1156 static int fib_check_nh_nongw(struct net *net, struct fib_nh *nh,
1157                               struct netlink_ext_ack *extack)
1158 {
1159         struct in_device *in_dev;
1160         int err;
1161
1162         if (nh->fib_nh_flags & (RTNH_F_PERVASIVE | RTNH_F_ONLINK)) {
1163                 NL_SET_ERR_MSG(extack,
1164                                "Invalid flags for nexthop - PERVASIVE and ONLINK can not be set");
1165                 return -EINVAL;
1166         }
1167
1168         rcu_read_lock();
1169
1170         err = -ENODEV;
1171         in_dev = inetdev_by_index(net, nh->fib_nh_oif);
1172         if (!in_dev)
1173                 goto out;
1174         err = -ENETDOWN;
1175         if (!(in_dev->dev->flags & IFF_UP)) {
1176                 NL_SET_ERR_MSG(extack, "Device for nexthop is not up");
1177                 goto out;
1178         }
1179
1180         nh->fib_nh_dev = in_dev->dev;
1181         dev_hold(nh->fib_nh_dev);
1182         nh->fib_nh_scope = RT_SCOPE_HOST;
1183         if (!netif_carrier_ok(nh->fib_nh_dev))
1184                 nh->fib_nh_flags |= RTNH_F_LINKDOWN;
1185         err = 0;
1186 out:
1187         rcu_read_unlock();
1188         return err;
1189 }
1190
1191 int fib_check_nh(struct net *net, struct fib_nh *nh, u32 table, u8 scope,
1192                  struct netlink_ext_ack *extack)
1193 {
1194         int err;
1195
1196         if (nh->fib_nh_gw_family == AF_INET)
1197                 err = fib_check_nh_v4_gw(net, nh, table, scope, extack);
1198         else if (nh->fib_nh_gw_family == AF_INET6)
1199                 err = fib_check_nh_v6_gw(net, nh, table, extack);
1200         else
1201                 err = fib_check_nh_nongw(net, nh, extack);
1202
1203         return err;
1204 }
1205
1206 static inline unsigned int fib_laddr_hashfn(__be32 val)
1207 {
1208         unsigned int mask = (fib_info_hash_size - 1);
1209
1210         return ((__force u32)val ^
1211                 ((__force u32)val >> 7) ^
1212                 ((__force u32)val >> 14)) & mask;
1213 }
1214
1215 static struct hlist_head *fib_info_hash_alloc(int bytes)
1216 {
1217         if (bytes <= PAGE_SIZE)
1218                 return kzalloc(bytes, GFP_KERNEL);
1219         else
1220                 return (struct hlist_head *)
1221                         __get_free_pages(GFP_KERNEL | __GFP_ZERO,
1222                                          get_order(bytes));
1223 }
1224
1225 static void fib_info_hash_free(struct hlist_head *hash, int bytes)
1226 {
1227         if (!hash)
1228                 return;
1229
1230         if (bytes <= PAGE_SIZE)
1231                 kfree(hash);
1232         else
1233                 free_pages((unsigned long) hash, get_order(bytes));
1234 }
1235
1236 static void fib_info_hash_move(struct hlist_head *new_info_hash,
1237                                struct hlist_head *new_laddrhash,
1238                                unsigned int new_size)
1239 {
1240         struct hlist_head *old_info_hash, *old_laddrhash;
1241         unsigned int old_size = fib_info_hash_size;
1242         unsigned int i, bytes;
1243
1244         spin_lock_bh(&fib_info_lock);
1245         old_info_hash = fib_info_hash;
1246         old_laddrhash = fib_info_laddrhash;
1247         fib_info_hash_size = new_size;
1248
1249         for (i = 0; i < old_size; i++) {
1250                 struct hlist_head *head = &fib_info_hash[i];
1251                 struct hlist_node *n;
1252                 struct fib_info *fi;
1253
1254                 hlist_for_each_entry_safe(fi, n, head, fib_hash) {
1255                         struct hlist_head *dest;
1256                         unsigned int new_hash;
1257
1258                         new_hash = fib_info_hashfn(fi);
1259                         dest = &new_info_hash[new_hash];
1260                         hlist_add_head(&fi->fib_hash, dest);
1261                 }
1262         }
1263         fib_info_hash = new_info_hash;
1264
1265         for (i = 0; i < old_size; i++) {
1266                 struct hlist_head *lhead = &fib_info_laddrhash[i];
1267                 struct hlist_node *n;
1268                 struct fib_info *fi;
1269
1270                 hlist_for_each_entry_safe(fi, n, lhead, fib_lhash) {
1271                         struct hlist_head *ldest;
1272                         unsigned int new_hash;
1273
1274                         new_hash = fib_laddr_hashfn(fi->fib_prefsrc);
1275                         ldest = &new_laddrhash[new_hash];
1276                         hlist_add_head(&fi->fib_lhash, ldest);
1277                 }
1278         }
1279         fib_info_laddrhash = new_laddrhash;
1280
1281         spin_unlock_bh(&fib_info_lock);
1282
1283         bytes = old_size * sizeof(struct hlist_head *);
1284         fib_info_hash_free(old_info_hash, bytes);
1285         fib_info_hash_free(old_laddrhash, bytes);
1286 }
1287
1288 __be32 fib_info_update_nhc_saddr(struct net *net, struct fib_nh_common *nhc,
1289                                  unsigned char scope)
1290 {
1291         struct fib_nh *nh;
1292
1293         if (nhc->nhc_family != AF_INET)
1294                 return inet_select_addr(nhc->nhc_dev, 0, scope);
1295
1296         nh = container_of(nhc, struct fib_nh, nh_common);
1297         nh->nh_saddr = inet_select_addr(nh->fib_nh_dev, nh->fib_nh_gw4, scope);
1298         nh->nh_saddr_genid = atomic_read(&net->ipv4.dev_addr_genid);
1299
1300         return nh->nh_saddr;
1301 }
1302
1303 __be32 fib_result_prefsrc(struct net *net, struct fib_result *res)
1304 {
1305         struct fib_nh_common *nhc = res->nhc;
1306
1307         if (res->fi->fib_prefsrc)
1308                 return res->fi->fib_prefsrc;
1309
1310         if (nhc->nhc_family == AF_INET) {
1311                 struct fib_nh *nh;
1312
1313                 nh = container_of(nhc, struct fib_nh, nh_common);
1314                 if (nh->nh_saddr_genid == atomic_read(&net->ipv4.dev_addr_genid))
1315                         return nh->nh_saddr;
1316         }
1317
1318         return fib_info_update_nhc_saddr(net, nhc, res->fi->fib_scope);
1319 }
1320
1321 static bool fib_valid_prefsrc(struct fib_config *cfg, __be32 fib_prefsrc)
1322 {
1323         if (cfg->fc_type != RTN_LOCAL || !cfg->fc_dst ||
1324             fib_prefsrc != cfg->fc_dst) {
1325                 u32 tb_id = cfg->fc_table;
1326                 int rc;
1327
1328                 if (tb_id == RT_TABLE_MAIN)
1329                         tb_id = RT_TABLE_LOCAL;
1330
1331                 rc = inet_addr_type_table(cfg->fc_nlinfo.nl_net,
1332                                           fib_prefsrc, tb_id);
1333
1334                 if (rc != RTN_LOCAL && tb_id != RT_TABLE_LOCAL) {
1335                         rc = inet_addr_type_table(cfg->fc_nlinfo.nl_net,
1336                                                   fib_prefsrc, RT_TABLE_LOCAL);
1337                 }
1338
1339                 if (rc != RTN_LOCAL)
1340                         return false;
1341         }
1342         return true;
1343 }
1344
1345 struct fib_info *fib_create_info(struct fib_config *cfg,
1346                                  struct netlink_ext_ack *extack)
1347 {
1348         int err;
1349         struct fib_info *fi = NULL;
1350         struct nexthop *nh = NULL;
1351         struct fib_info *ofi;
1352         int nhs = 1;
1353         struct net *net = cfg->fc_nlinfo.nl_net;
1354
1355         if (cfg->fc_type > RTN_MAX)
1356                 goto err_inval;
1357
1358         /* Fast check to catch the most weird cases */
1359         if (fib_props[cfg->fc_type].scope > cfg->fc_scope) {
1360                 NL_SET_ERR_MSG(extack, "Invalid scope");
1361                 goto err_inval;
1362         }
1363
1364         if (cfg->fc_flags & (RTNH_F_DEAD | RTNH_F_LINKDOWN)) {
1365                 NL_SET_ERR_MSG(extack,
1366                                "Invalid rtm_flags - can not contain DEAD or LINKDOWN");
1367                 goto err_inval;
1368         }
1369
1370         if (cfg->fc_nh_id) {
1371                 if (!cfg->fc_mx) {
1372                         fi = fib_find_info_nh(net, cfg);
1373                         if (fi) {
1374                                 refcount_inc(&fi->fib_treeref);
1375                                 return fi;
1376                         }
1377                 }
1378
1379                 nh = nexthop_find_by_id(net, cfg->fc_nh_id);
1380                 if (!nh) {
1381                         NL_SET_ERR_MSG(extack, "Nexthop id does not exist");
1382                         goto err_inval;
1383                 }
1384                 nhs = 0;
1385         }
1386
1387 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1388         if (cfg->fc_mp) {
1389                 nhs = fib_count_nexthops(cfg->fc_mp, cfg->fc_mp_len, extack);
1390                 if (nhs == 0)
1391                         goto err_inval;
1392         }
1393 #endif
1394
1395         err = -ENOBUFS;
1396         if (fib_info_cnt >= fib_info_hash_size) {
1397                 unsigned int new_size = fib_info_hash_size << 1;
1398                 struct hlist_head *new_info_hash;
1399                 struct hlist_head *new_laddrhash;
1400                 unsigned int bytes;
1401
1402                 if (!new_size)
1403                         new_size = 16;
1404                 bytes = new_size * sizeof(struct hlist_head *);
1405                 new_info_hash = fib_info_hash_alloc(bytes);
1406                 new_laddrhash = fib_info_hash_alloc(bytes);
1407                 if (!new_info_hash || !new_laddrhash) {
1408                         fib_info_hash_free(new_info_hash, bytes);
1409                         fib_info_hash_free(new_laddrhash, bytes);
1410                 } else
1411                         fib_info_hash_move(new_info_hash, new_laddrhash, new_size);
1412
1413                 if (!fib_info_hash_size)
1414                         goto failure;
1415         }
1416
1417         fi = kzalloc(struct_size(fi, fib_nh, nhs), GFP_KERNEL);
1418         if (!fi)
1419                 goto failure;
1420         fi->fib_metrics = ip_fib_metrics_init(fi->fib_net, cfg->fc_mx,
1421                                               cfg->fc_mx_len, extack);
1422         if (IS_ERR(fi->fib_metrics)) {
1423                 err = PTR_ERR(fi->fib_metrics);
1424                 kfree(fi);
1425                 return ERR_PTR(err);
1426         }
1427
1428         fib_info_cnt++;
1429         fi->fib_net = net;
1430         fi->fib_protocol = cfg->fc_protocol;
1431         fi->fib_scope = cfg->fc_scope;
1432         fi->fib_flags = cfg->fc_flags;
1433         fi->fib_priority = cfg->fc_priority;
1434         fi->fib_prefsrc = cfg->fc_prefsrc;
1435         fi->fib_type = cfg->fc_type;
1436         fi->fib_tb_id = cfg->fc_table;
1437
1438         fi->fib_nhs = nhs;
1439         if (nh) {
1440                 if (!nexthop_get(nh)) {
1441                         NL_SET_ERR_MSG(extack, "Nexthop has been deleted");
1442                         err = -EINVAL;
1443                 } else {
1444                         err = 0;
1445                         fi->nh = nh;
1446                 }
1447         } else {
1448                 change_nexthops(fi) {
1449                         nexthop_nh->nh_parent = fi;
1450                 } endfor_nexthops(fi)
1451
1452                 if (cfg->fc_mp)
1453                         err = fib_get_nhs(fi, cfg->fc_mp, cfg->fc_mp_len, cfg,
1454                                           extack);
1455                 else
1456                         err = fib_nh_init(net, fi->fib_nh, cfg, 1, extack);
1457         }
1458
1459         if (err != 0)
1460                 goto failure;
1461
1462         if (fib_props[cfg->fc_type].error) {
1463                 if (cfg->fc_gw_family || cfg->fc_oif || cfg->fc_mp) {
1464                         NL_SET_ERR_MSG(extack,
1465                                        "Gateway, device and multipath can not be specified for this route type");
1466                         goto err_inval;
1467                 }
1468                 goto link_it;
1469         } else {
1470                 switch (cfg->fc_type) {
1471                 case RTN_UNICAST:
1472                 case RTN_LOCAL:
1473                 case RTN_BROADCAST:
1474                 case RTN_ANYCAST:
1475                 case RTN_MULTICAST:
1476                         break;
1477                 default:
1478                         NL_SET_ERR_MSG(extack, "Invalid route type");
1479                         goto err_inval;
1480                 }
1481         }
1482
1483         if (cfg->fc_scope > RT_SCOPE_HOST) {
1484                 NL_SET_ERR_MSG(extack, "Invalid scope");
1485                 goto err_inval;
1486         }
1487
1488         if (fi->nh) {
1489                 err = fib_check_nexthop(fi->nh, cfg->fc_scope, extack);
1490                 if (err)
1491                         goto failure;
1492         } else if (cfg->fc_scope == RT_SCOPE_HOST) {
1493                 struct fib_nh *nh = fi->fib_nh;
1494
1495                 /* Local address is added. */
1496                 if (nhs != 1) {
1497                         NL_SET_ERR_MSG(extack,
1498                                        "Route with host scope can not have multiple nexthops");
1499                         goto err_inval;
1500                 }
1501                 if (nh->fib_nh_gw_family) {
1502                         NL_SET_ERR_MSG(extack,
1503                                        "Route with host scope can not have a gateway");
1504                         goto err_inval;
1505                 }
1506                 nh->fib_nh_scope = RT_SCOPE_NOWHERE;
1507                 nh->fib_nh_dev = dev_get_by_index(net, nh->fib_nh_oif);
1508                 err = -ENODEV;
1509                 if (!nh->fib_nh_dev)
1510                         goto failure;
1511         } else {
1512                 int linkdown = 0;
1513
1514                 change_nexthops(fi) {
1515                         err = fib_check_nh(cfg->fc_nlinfo.nl_net, nexthop_nh,
1516                                            cfg->fc_table, cfg->fc_scope,
1517                                            extack);
1518                         if (err != 0)
1519                                 goto failure;
1520                         if (nexthop_nh->fib_nh_flags & RTNH_F_LINKDOWN)
1521                                 linkdown++;
1522                 } endfor_nexthops(fi)
1523                 if (linkdown == fi->fib_nhs)
1524                         fi->fib_flags |= RTNH_F_LINKDOWN;
1525         }
1526
1527         if (fi->fib_prefsrc && !fib_valid_prefsrc(cfg, fi->fib_prefsrc)) {
1528                 NL_SET_ERR_MSG(extack, "Invalid prefsrc address");
1529                 goto err_inval;
1530         }
1531
1532         if (!fi->nh) {
1533                 change_nexthops(fi) {
1534                         fib_info_update_nhc_saddr(net, &nexthop_nh->nh_common,
1535                                                   fi->fib_scope);
1536                         if (nexthop_nh->fib_nh_gw_family == AF_INET6)
1537                                 fi->fib_nh_is_v6 = true;
1538                 } endfor_nexthops(fi)
1539
1540                 fib_rebalance(fi);
1541         }
1542
1543 link_it:
1544         ofi = fib_find_info(fi);
1545         if (ofi) {
1546                 fi->fib_dead = 1;
1547                 free_fib_info(fi);
1548                 refcount_inc(&ofi->fib_treeref);
1549                 return ofi;
1550         }
1551
1552         refcount_set(&fi->fib_treeref, 1);
1553         refcount_set(&fi->fib_clntref, 1);
1554         spin_lock_bh(&fib_info_lock);
1555         hlist_add_head(&fi->fib_hash,
1556                        &fib_info_hash[fib_info_hashfn(fi)]);
1557         if (fi->fib_prefsrc) {
1558                 struct hlist_head *head;
1559
1560                 head = &fib_info_laddrhash[fib_laddr_hashfn(fi->fib_prefsrc)];
1561                 hlist_add_head(&fi->fib_lhash, head);
1562         }
1563         if (fi->nh) {
1564                 list_add(&fi->nh_list, &nh->fi_list);
1565         } else {
1566                 change_nexthops(fi) {
1567                         struct hlist_head *head;
1568                         unsigned int hash;
1569
1570                         if (!nexthop_nh->fib_nh_dev)
1571                                 continue;
1572                         hash = fib_devindex_hashfn(nexthop_nh->fib_nh_dev->ifindex);
1573                         head = &fib_info_devhash[hash];
1574                         hlist_add_head(&nexthop_nh->nh_hash, head);
1575                 } endfor_nexthops(fi)
1576         }
1577         spin_unlock_bh(&fib_info_lock);
1578         return fi;
1579
1580 err_inval:
1581         err = -EINVAL;
1582
1583 failure:
1584         if (fi) {
1585                 fi->fib_dead = 1;
1586                 free_fib_info(fi);
1587         }
1588
1589         return ERR_PTR(err);
1590 }
1591
1592 int fib_nexthop_info(struct sk_buff *skb, const struct fib_nh_common *nhc,
1593                      u8 rt_family, unsigned char *flags, bool skip_oif)
1594 {
1595         if (nhc->nhc_flags & RTNH_F_DEAD)
1596                 *flags |= RTNH_F_DEAD;
1597
1598         if (nhc->nhc_flags & RTNH_F_LINKDOWN) {
1599                 *flags |= RTNH_F_LINKDOWN;
1600
1601                 rcu_read_lock();
1602                 switch (nhc->nhc_family) {
1603                 case AF_INET:
1604                         if (ip_ignore_linkdown(nhc->nhc_dev))
1605                                 *flags |= RTNH_F_DEAD;
1606                         break;
1607                 case AF_INET6:
1608                         if (ip6_ignore_linkdown(nhc->nhc_dev))
1609                                 *flags |= RTNH_F_DEAD;
1610                         break;
1611                 }
1612                 rcu_read_unlock();
1613         }
1614
1615         switch (nhc->nhc_gw_family) {
1616         case AF_INET:
1617                 if (nla_put_in_addr(skb, RTA_GATEWAY, nhc->nhc_gw.ipv4))
1618                         goto nla_put_failure;
1619                 break;
1620         case AF_INET6:
1621                 /* if gateway family does not match nexthop family
1622                  * gateway is encoded as RTA_VIA
1623                  */
1624                 if (rt_family != nhc->nhc_gw_family) {
1625                         int alen = sizeof(struct in6_addr);
1626                         struct nlattr *nla;
1627                         struct rtvia *via;
1628
1629                         nla = nla_reserve(skb, RTA_VIA, alen + 2);
1630                         if (!nla)
1631                                 goto nla_put_failure;
1632
1633                         via = nla_data(nla);
1634                         via->rtvia_family = AF_INET6;
1635                         memcpy(via->rtvia_addr, &nhc->nhc_gw.ipv6, alen);
1636                 } else if (nla_put_in6_addr(skb, RTA_GATEWAY,
1637                                             &nhc->nhc_gw.ipv6) < 0) {
1638                         goto nla_put_failure;
1639                 }
1640                 break;
1641         }
1642
1643         *flags |= (nhc->nhc_flags &
1644                    (RTNH_F_ONLINK | RTNH_F_OFFLOAD | RTNH_F_TRAP));
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                   const 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                 if (!fi->fib_net->ipv4.sysctl_nexthop_compat_mode)
1782                         goto offload;
1783         }
1784
1785         if (nhs == 1) {
1786                 const struct fib_nh_common *nhc = fib_info_nhc(fi, 0);
1787                 unsigned char flags = 0;
1788
1789                 if (fib_nexthop_info(skb, nhc, AF_INET, &flags, false) < 0)
1790                         goto nla_put_failure;
1791
1792                 rtm->rtm_flags = flags;
1793 #ifdef CONFIG_IP_ROUTE_CLASSID
1794                 if (nhc->nhc_family == AF_INET) {
1795                         struct fib_nh *nh;
1796
1797                         nh = container_of(nhc, struct fib_nh, nh_common);
1798                         if (nh->nh_tclassid &&
1799                             nla_put_u32(skb, RTA_FLOW, nh->nh_tclassid))
1800                                 goto nla_put_failure;
1801                 }
1802 #endif
1803         } else {
1804                 if (fib_add_multipath(skb, fi) < 0)
1805                         goto nla_put_failure;
1806         }
1807
1808 offload:
1809         if (fri->offload)
1810                 rtm->rtm_flags |= RTM_F_OFFLOAD;
1811         if (fri->trap)
1812                 rtm->rtm_flags |= RTM_F_TRAP;
1813         if (fri->offload_failed)
1814                 rtm->rtm_flags |= RTM_F_OFFLOAD_FAILED;
1815
1816         nlmsg_end(skb, nlh);
1817         return 0;
1818
1819 nla_put_failure:
1820         nlmsg_cancel(skb, nlh);
1821         return -EMSGSIZE;
1822 }
1823
1824 /*
1825  * Update FIB if:
1826  * - local address disappeared -> we must delete all the entries
1827  *   referring to it.
1828  * - device went down -> we must shutdown all nexthops going via it.
1829  */
1830 int fib_sync_down_addr(struct net_device *dev, __be32 local)
1831 {
1832         int ret = 0;
1833         unsigned int hash = fib_laddr_hashfn(local);
1834         struct hlist_head *head = &fib_info_laddrhash[hash];
1835         int tb_id = l3mdev_fib_table(dev) ? : RT_TABLE_MAIN;
1836         struct net *net = dev_net(dev);
1837         struct fib_info *fi;
1838
1839         if (!fib_info_laddrhash || local == 0)
1840                 return 0;
1841
1842         hlist_for_each_entry(fi, head, fib_lhash) {
1843                 if (!net_eq(fi->fib_net, net) ||
1844                     fi->fib_tb_id != tb_id)
1845                         continue;
1846                 if (fi->fib_prefsrc == local) {
1847                         fi->fib_flags |= RTNH_F_DEAD;
1848                         ret++;
1849                 }
1850         }
1851         return ret;
1852 }
1853
1854 static int call_fib_nh_notifiers(struct fib_nh *nh,
1855                                  enum fib_event_type event_type)
1856 {
1857         bool ignore_link_down = ip_ignore_linkdown(nh->fib_nh_dev);
1858         struct fib_nh_notifier_info info = {
1859                 .fib_nh = nh,
1860         };
1861
1862         switch (event_type) {
1863         case FIB_EVENT_NH_ADD:
1864                 if (nh->fib_nh_flags & RTNH_F_DEAD)
1865                         break;
1866                 if (ignore_link_down && nh->fib_nh_flags & RTNH_F_LINKDOWN)
1867                         break;
1868                 return call_fib4_notifiers(dev_net(nh->fib_nh_dev), event_type,
1869                                            &info.info);
1870         case FIB_EVENT_NH_DEL:
1871                 if ((ignore_link_down && nh->fib_nh_flags & RTNH_F_LINKDOWN) ||
1872                     (nh->fib_nh_flags & RTNH_F_DEAD))
1873                         return call_fib4_notifiers(dev_net(nh->fib_nh_dev),
1874                                                    event_type, &info.info);
1875                 break;
1876         default:
1877                 break;
1878         }
1879
1880         return NOTIFY_DONE;
1881 }
1882
1883 /* Update the PMTU of exceptions when:
1884  * - the new MTU of the first hop becomes smaller than the PMTU
1885  * - the old MTU was the same as the PMTU, and it limited discovery of
1886  *   larger MTUs on the path. With that limit raised, we can now
1887  *   discover larger MTUs
1888  * A special case is locked exceptions, for which the PMTU is smaller
1889  * than the minimal accepted PMTU:
1890  * - if the new MTU is greater than the PMTU, don't make any change
1891  * - otherwise, unlock and set PMTU
1892  */
1893 void fib_nhc_update_mtu(struct fib_nh_common *nhc, u32 new, u32 orig)
1894 {
1895         struct fnhe_hash_bucket *bucket;
1896         int i;
1897
1898         bucket = rcu_dereference_protected(nhc->nhc_exceptions, 1);
1899         if (!bucket)
1900                 return;
1901
1902         for (i = 0; i < FNHE_HASH_SIZE; i++) {
1903                 struct fib_nh_exception *fnhe;
1904
1905                 for (fnhe = rcu_dereference_protected(bucket[i].chain, 1);
1906                      fnhe;
1907                      fnhe = rcu_dereference_protected(fnhe->fnhe_next, 1)) {
1908                         if (fnhe->fnhe_mtu_locked) {
1909                                 if (new <= fnhe->fnhe_pmtu) {
1910                                         fnhe->fnhe_pmtu = new;
1911                                         fnhe->fnhe_mtu_locked = false;
1912                                 }
1913                         } else if (new < fnhe->fnhe_pmtu ||
1914                                    orig == fnhe->fnhe_pmtu) {
1915                                 fnhe->fnhe_pmtu = new;
1916                         }
1917                 }
1918         }
1919 }
1920
1921 void fib_sync_mtu(struct net_device *dev, u32 orig_mtu)
1922 {
1923         unsigned int hash = fib_devindex_hashfn(dev->ifindex);
1924         struct hlist_head *head = &fib_info_devhash[hash];
1925         struct fib_nh *nh;
1926
1927         hlist_for_each_entry(nh, head, nh_hash) {
1928                 if (nh->fib_nh_dev == dev)
1929                         fib_nhc_update_mtu(&nh->nh_common, dev->mtu, orig_mtu);
1930         }
1931 }
1932
1933 /* Event              force Flags           Description
1934  * NETDEV_CHANGE      0     LINKDOWN        Carrier OFF, not for scope host
1935  * NETDEV_DOWN        0     LINKDOWN|DEAD   Link down, not for scope host
1936  * NETDEV_DOWN        1     LINKDOWN|DEAD   Last address removed
1937  * NETDEV_UNREGISTER  1     LINKDOWN|DEAD   Device removed
1938  *
1939  * only used when fib_nh is built into fib_info
1940  */
1941 int fib_sync_down_dev(struct net_device *dev, unsigned long event, bool force)
1942 {
1943         int ret = 0;
1944         int scope = RT_SCOPE_NOWHERE;
1945         struct fib_info *prev_fi = NULL;
1946         unsigned int hash = fib_devindex_hashfn(dev->ifindex);
1947         struct hlist_head *head = &fib_info_devhash[hash];
1948         struct fib_nh *nh;
1949
1950         if (force)
1951                 scope = -1;
1952
1953         hlist_for_each_entry(nh, head, nh_hash) {
1954                 struct fib_info *fi = nh->nh_parent;
1955                 int dead;
1956
1957                 BUG_ON(!fi->fib_nhs);
1958                 if (nh->fib_nh_dev != dev || fi == prev_fi)
1959                         continue;
1960                 prev_fi = fi;
1961                 dead = 0;
1962                 change_nexthops(fi) {
1963                         if (nexthop_nh->fib_nh_flags & RTNH_F_DEAD)
1964                                 dead++;
1965                         else if (nexthop_nh->fib_nh_dev == dev &&
1966                                  nexthop_nh->fib_nh_scope != scope) {
1967                                 switch (event) {
1968                                 case NETDEV_DOWN:
1969                                 case NETDEV_UNREGISTER:
1970                                         nexthop_nh->fib_nh_flags |= RTNH_F_DEAD;
1971                                         fallthrough;
1972                                 case NETDEV_CHANGE:
1973                                         nexthop_nh->fib_nh_flags |= RTNH_F_LINKDOWN;
1974                                         break;
1975                                 }
1976                                 call_fib_nh_notifiers(nexthop_nh,
1977                                                       FIB_EVENT_NH_DEL);
1978                                 dead++;
1979                         }
1980 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1981                         if (event == NETDEV_UNREGISTER &&
1982                             nexthop_nh->fib_nh_dev == dev) {
1983                                 dead = fi->fib_nhs;
1984                                 break;
1985                         }
1986 #endif
1987                 } endfor_nexthops(fi)
1988                 if (dead == fi->fib_nhs) {
1989                         switch (event) {
1990                         case NETDEV_DOWN:
1991                         case NETDEV_UNREGISTER:
1992                                 fi->fib_flags |= RTNH_F_DEAD;
1993                                 fallthrough;
1994                         case NETDEV_CHANGE:
1995                                 fi->fib_flags |= RTNH_F_LINKDOWN;
1996                                 break;
1997                         }
1998                         ret++;
1999                 }
2000
2001                 fib_rebalance(fi);
2002         }
2003
2004         return ret;
2005 }
2006
2007 /* Must be invoked inside of an RCU protected region.  */
2008 static void fib_select_default(const struct flowi4 *flp, struct fib_result *res)
2009 {
2010         struct fib_info *fi = NULL, *last_resort = NULL;
2011         struct hlist_head *fa_head = res->fa_head;
2012         struct fib_table *tb = res->table;
2013         u8 slen = 32 - res->prefixlen;
2014         int order = -1, last_idx = -1;
2015         struct fib_alias *fa, *fa1 = NULL;
2016         u32 last_prio = res->fi->fib_priority;
2017         u8 last_tos = 0;
2018
2019         hlist_for_each_entry_rcu(fa, fa_head, fa_list) {
2020                 struct fib_info *next_fi = fa->fa_info;
2021                 struct fib_nh_common *nhc;
2022
2023                 if (fa->fa_slen != slen)
2024                         continue;
2025                 if (fa->fa_tos && fa->fa_tos != flp->flowi4_tos)
2026                         continue;
2027                 if (fa->tb_id != tb->tb_id)
2028                         continue;
2029                 if (next_fi->fib_priority > last_prio &&
2030                     fa->fa_tos == last_tos) {
2031                         if (last_tos)
2032                                 continue;
2033                         break;
2034                 }
2035                 if (next_fi->fib_flags & RTNH_F_DEAD)
2036                         continue;
2037                 last_tos = fa->fa_tos;
2038                 last_prio = next_fi->fib_priority;
2039
2040                 if (next_fi->fib_scope != res->scope ||
2041                     fa->fa_type != RTN_UNICAST)
2042                         continue;
2043
2044                 nhc = fib_info_nhc(next_fi, 0);
2045                 if (!nhc->nhc_gw_family || nhc->nhc_scope != RT_SCOPE_LINK)
2046                         continue;
2047
2048                 fib_alias_accessed(fa);
2049
2050                 if (!fi) {
2051                         if (next_fi != res->fi)
2052                                 break;
2053                         fa1 = fa;
2054                 } else if (!fib_detect_death(fi, order, &last_resort,
2055                                              &last_idx, fa1->fa_default)) {
2056                         fib_result_assign(res, fi);
2057                         fa1->fa_default = order;
2058                         goto out;
2059                 }
2060                 fi = next_fi;
2061                 order++;
2062         }
2063
2064         if (order <= 0 || !fi) {
2065                 if (fa1)
2066                         fa1->fa_default = -1;
2067                 goto out;
2068         }
2069
2070         if (!fib_detect_death(fi, order, &last_resort, &last_idx,
2071                               fa1->fa_default)) {
2072                 fib_result_assign(res, fi);
2073                 fa1->fa_default = order;
2074                 goto out;
2075         }
2076
2077         if (last_idx >= 0)
2078                 fib_result_assign(res, last_resort);
2079         fa1->fa_default = last_idx;
2080 out:
2081         return;
2082 }
2083
2084 /*
2085  * Dead device goes up. We wake up dead nexthops.
2086  * It takes sense only on multipath routes.
2087  *
2088  * only used when fib_nh is built into fib_info
2089  */
2090 int fib_sync_up(struct net_device *dev, unsigned char nh_flags)
2091 {
2092         struct fib_info *prev_fi;
2093         unsigned int hash;
2094         struct hlist_head *head;
2095         struct fib_nh *nh;
2096         int ret;
2097
2098         if (!(dev->flags & IFF_UP))
2099                 return 0;
2100
2101         if (nh_flags & RTNH_F_DEAD) {
2102                 unsigned int flags = dev_get_flags(dev);
2103
2104                 if (flags & (IFF_RUNNING | IFF_LOWER_UP))
2105                         nh_flags |= RTNH_F_LINKDOWN;
2106         }
2107
2108         prev_fi = NULL;
2109         hash = fib_devindex_hashfn(dev->ifindex);
2110         head = &fib_info_devhash[hash];
2111         ret = 0;
2112
2113         hlist_for_each_entry(nh, head, nh_hash) {
2114                 struct fib_info *fi = nh->nh_parent;
2115                 int alive;
2116
2117                 BUG_ON(!fi->fib_nhs);
2118                 if (nh->fib_nh_dev != dev || fi == prev_fi)
2119                         continue;
2120
2121                 prev_fi = fi;
2122                 alive = 0;
2123                 change_nexthops(fi) {
2124                         if (!(nexthop_nh->fib_nh_flags & nh_flags)) {
2125                                 alive++;
2126                                 continue;
2127                         }
2128                         if (!nexthop_nh->fib_nh_dev ||
2129                             !(nexthop_nh->fib_nh_dev->flags & IFF_UP))
2130                                 continue;
2131                         if (nexthop_nh->fib_nh_dev != dev ||
2132                             !__in_dev_get_rtnl(dev))
2133                                 continue;
2134                         alive++;
2135                         nexthop_nh->fib_nh_flags &= ~nh_flags;
2136                         call_fib_nh_notifiers(nexthop_nh, FIB_EVENT_NH_ADD);
2137                 } endfor_nexthops(fi)
2138
2139                 if (alive > 0) {
2140                         fi->fib_flags &= ~nh_flags;
2141                         ret++;
2142                 }
2143
2144                 fib_rebalance(fi);
2145         }
2146
2147         return ret;
2148 }
2149
2150 #ifdef CONFIG_IP_ROUTE_MULTIPATH
2151 static bool fib_good_nh(const struct fib_nh *nh)
2152 {
2153         int state = NUD_REACHABLE;
2154
2155         if (nh->fib_nh_scope == RT_SCOPE_LINK) {
2156                 struct neighbour *n;
2157
2158                 rcu_read_lock_bh();
2159
2160                 if (likely(nh->fib_nh_gw_family == AF_INET))
2161                         n = __ipv4_neigh_lookup_noref(nh->fib_nh_dev,
2162                                                    (__force u32)nh->fib_nh_gw4);
2163                 else if (nh->fib_nh_gw_family == AF_INET6)
2164                         n = __ipv6_neigh_lookup_noref_stub(nh->fib_nh_dev,
2165                                                            &nh->fib_nh_gw6);
2166                 else
2167                         n = NULL;
2168                 if (n)
2169                         state = n->nud_state;
2170
2171                 rcu_read_unlock_bh();
2172         }
2173
2174         return !!(state & NUD_VALID);
2175 }
2176
2177 void fib_select_multipath(struct fib_result *res, int hash)
2178 {
2179         struct fib_info *fi = res->fi;
2180         struct net *net = fi->fib_net;
2181         bool first = false;
2182
2183         if (unlikely(res->fi->nh)) {
2184                 nexthop_path_fib_result(res, hash);
2185                 return;
2186         }
2187
2188         change_nexthops(fi) {
2189                 if (net->ipv4.sysctl_fib_multipath_use_neigh) {
2190                         if (!fib_good_nh(nexthop_nh))
2191                                 continue;
2192                         if (!first) {
2193                                 res->nh_sel = nhsel;
2194                                 res->nhc = &nexthop_nh->nh_common;
2195                                 first = true;
2196                         }
2197                 }
2198
2199                 if (hash > atomic_read(&nexthop_nh->fib_nh_upper_bound))
2200                         continue;
2201
2202                 res->nh_sel = nhsel;
2203                 res->nhc = &nexthop_nh->nh_common;
2204                 return;
2205         } endfor_nexthops(fi);
2206 }
2207 #endif
2208
2209 void fib_select_path(struct net *net, struct fib_result *res,
2210                      struct flowi4 *fl4, const struct sk_buff *skb)
2211 {
2212         if (fl4->flowi4_oif && !(fl4->flowi4_flags & FLOWI_FLAG_SKIP_NH_OIF))
2213                 goto check_saddr;
2214
2215 #ifdef CONFIG_IP_ROUTE_MULTIPATH
2216         if (fib_info_num_path(res->fi) > 1) {
2217                 int h = fib_multipath_hash(net, fl4, skb, NULL);
2218
2219                 fib_select_multipath(res, h);
2220         }
2221         else
2222 #endif
2223         if (!res->prefixlen &&
2224             res->table->tb_num_default > 1 &&
2225             res->type == RTN_UNICAST)
2226                 fib_select_default(fl4, res);
2227
2228 check_saddr:
2229         if (!fl4->saddr)
2230                 fl4->saddr = fib_result_prefsrc(net, res);
2231 }