net/ipv4/fib_semantics.c

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