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/netlink.h>
  45 #include <net/nexthop.h>
  46 #include <net/lwtunnel.h>
  47 #include <net/fib_notifier.h>
  48
  49 #include "fib_lookup.h"
  50
  51 static DEFINE_SPINLOCK(fib_info_lock);
  52 static struct hlist_head *fib_info_hash;
  53 static struct hlist_head *fib_info_laddrhash;
  54 static unsigned int fib_info_hash_size;
  55 static unsigned int fib_info_cnt;
  56
  57 #define DEVINDEX_HASHBITS 8
  58 #define DEVINDEX_HASHSIZE (1U << DEVINDEX_HASHBITS)
  59 static struct hlist_head fib_info_devhash[DEVINDEX_HASHSIZE];
  60
  61 #ifdef CONFIG_IP_ROUTE_MULTIPATH
  62
  63 #define for_nexthops(fi) {                                              \
  64         int nhsel; const struct fib_nh *nh;                             \
  65         for (nhsel = 0, nh = (fi)->fib_nh;                              \
  66              nhsel < (fi)->fib_nhs;                                     \
  67              nh++, nhsel++)
  68
  69 #define change_nexthops(fi) {                                           \
  70         int nhsel; struct fib_nh *nexthop_nh;                           \
  71         for (nhsel = 0, nexthop_nh = (struct fib_nh *)((fi)->fib_nh);   \
  72              nhsel < (fi)->fib_nhs;                                     \
  73              nexthop_nh++, nhsel++)
  74
  75 #else /* CONFIG_IP_ROUTE_MULTIPATH */
  76
  77 /* Hope, that gcc will optimize it to get rid of dummy loop */
  78
  79 #define for_nexthops(fi) {                                              \
  80         int nhsel; const struct fib_nh *nh = (fi)->fib_nh;              \
  81         for (nhsel = 0; nhsel < 1; nhsel++)
  82
  83 #define change_nexthops(fi) {                                           \
  84         int nhsel;                                                      \
  85         struct fib_nh *nexthop_nh = (struct fib_nh *)((fi)->fib_nh);    \
  86         for (nhsel = 0; nhsel < 1; nhsel++)
  87
  88 #endif /* CONFIG_IP_ROUTE_MULTIPATH */
  89
  90 #define endfor_nexthops(fi) }
  91
  92
  93 const struct fib_prop fib_props[RTN_MAX + 1] = {
  94         [RTN_UNSPEC] = {
  95                 .error  = 0,
  96                 .scope  = RT_SCOPE_NOWHERE,
  97         },
  98         [RTN_UNICAST] = {
  99                 .error  = 0,
 100                 .scope  = RT_SCOPE_UNIVERSE,
 101         },
 102         [RTN_LOCAL] = {
 103                 .error  = 0,
 104                 .scope  = RT_SCOPE_HOST,
 105         },
 106         [RTN_BROADCAST] = {
 107                 .error  = 0,
 108                 .scope  = RT_SCOPE_LINK,
 109         },
 110         [RTN_ANYCAST] = {
 111                 .error  = 0,
 112                 .scope  = RT_SCOPE_LINK,
 113         },
 114         [RTN_MULTICAST] = {
 115                 .error  = 0,
 116                 .scope  = RT_SCOPE_UNIVERSE,
 117         },
 118         [RTN_BLACKHOLE] = {
 119                 .error  = -EINVAL,
 120                 .scope  = RT_SCOPE_UNIVERSE,
 121         },
 122         [RTN_UNREACHABLE] = {
 123                 .error  = -EHOSTUNREACH,
 124                 .scope  = RT_SCOPE_UNIVERSE,
 125         },
 126         [RTN_PROHIBIT] = {
 127                 .error  = -EACCES,
 128                 .scope  = RT_SCOPE_UNIVERSE,
 129         },
 130         [RTN_THROW] = {
 131                 .error  = -EAGAIN,
 132                 .scope  = RT_SCOPE_UNIVERSE,
 133         },
 134         [RTN_NAT] = {
 135                 .error  = -EINVAL,
 136                 .scope  = RT_SCOPE_NOWHERE,
 137         },
 138         [RTN_XRESOLVE] = {
 139                 .error  = -EINVAL,
 140                 .scope  = RT_SCOPE_NOWHERE,
 141         },
 142 };
 143
 144 static void rt_fibinfo_free(struct rtable __rcu **rtp)
 145 {
 146         struct rtable *rt = rcu_dereference_protected(*rtp, 1);
 147
 148         if (!rt)
 149                 return;
 150
 151         /* Not even needed : RCU_INIT_POINTER(*rtp, NULL);
 152          * because we waited an RCU grace period before calling
 153          * free_fib_info_rcu()
 154          */
 155
 156         dst_dev_put(&rt->dst);
 157         dst_release_immediate(&rt->dst);
 158 }
 159
 160 static void free_nh_exceptions(struct fib_nh *nh)
 161 {
 162         struct fnhe_hash_bucket *hash;
 163         int i;
 164
 165         hash = rcu_dereference_protected(nh->nh_exceptions, 1);
 166         if (!hash)
 167                 return;
 168         for (i = 0; i < FNHE_HASH_SIZE; i++) {
 169                 struct fib_nh_exception *fnhe;
 170
 171                 fnhe = rcu_dereference_protected(hash[i].chain, 1);
 172                 while (fnhe) {
 173                         struct fib_nh_exception *next;
 174
 175                         next = rcu_dereference_protected(fnhe->fnhe_next, 1);
 176
 177                         rt_fibinfo_free(&fnhe->fnhe_rth_input);
 178                         rt_fibinfo_free(&fnhe->fnhe_rth_output);
 179
 180                         kfree(fnhe);
 181
 182                         fnhe = next;
 183                 }
 184         }
 185         kfree(hash);
 186 }
 187
 188 static void rt_fibinfo_free_cpus(struct rtable __rcu * __percpu *rtp)
 189 {
 190         int cpu;
 191
 192         if (!rtp)
 193                 return;
 194
 195         for_each_possible_cpu(cpu) {
 196                 struct rtable *rt;
 197
 198                 rt = rcu_dereference_protected(*per_cpu_ptr(rtp, cpu), 1);
 199                 if (rt) {
 200                         dst_dev_put(&rt->dst);
 201                         dst_release_immediate(&rt->dst);
 202                 }
 203         }
 204         free_percpu(rtp);
 205 }
 206
 207 /* Release a nexthop info record */
 208 static void free_fib_info_rcu(struct rcu_head *head)
 209 {
 210         struct fib_info *fi = container_of(head, struct fib_info, rcu);
 211         struct dst_metrics *m;
 212
 213         change_nexthops(fi) {
 214                 if (nexthop_nh->nh_dev)
 215                         dev_put(nexthop_nh->nh_dev);
 216                 lwtstate_put(nexthop_nh->nh_lwtstate);
 217                 free_nh_exceptions(nexthop_nh);
 218                 rt_fibinfo_free_cpus(nexthop_nh->nh_pcpu_rth_output);
 219                 rt_fibinfo_free(&nexthop_nh->nh_rth_input);
 220         } endfor_nexthops(fi);
 221
 222         m = fi->fib_metrics;
 223         if (m != &dst_default_metrics && refcount_dec_and_test(&m->refcnt))
 224                 kfree(m);
 225         kfree(fi);
 226 }
 227
 228 void free_fib_info(struct fib_info *fi)
 229 {
 230         if (fi->fib_dead == 0) {
 231                 pr_warn("Freeing alive fib_info %p\n", fi);
 232                 return;
 233         }
 234         fib_info_cnt--;
 235 #ifdef CONFIG_IP_ROUTE_CLASSID
 236         change_nexthops(fi) {
 237                 if (nexthop_nh->nh_tclassid)
 238                         fi->fib_net->ipv4.fib_num_tclassid_users--;
 239         } endfor_nexthops(fi);
 240 #endif
 241         call_rcu(&fi->rcu, free_fib_info_rcu);
 242 }
 243 EXPORT_SYMBOL_GPL(free_fib_info);
 244
 245 void fib_release_info(struct fib_info *fi)
 246 {
 247         spin_lock_bh(&fib_info_lock);
 248         if (fi && --fi->fib_treeref == 0) {
 249                 hlist_del(&fi->fib_hash);
 250                 if (fi->fib_prefsrc)
 251                         hlist_del(&fi->fib_lhash);
 252                 change_nexthops(fi) {
 253                         if (!nexthop_nh->nh_dev)
 254                                 continue;
 255                         hlist_del(&nexthop_nh->nh_hash);
 256                 } endfor_nexthops(fi)
 257                 fi->fib_dead = 1;
 258                 fib_info_put(fi);
 259         }
 260         spin_unlock_bh(&fib_info_lock);
 261 }
 262
 263 static inline int nh_comp(const struct fib_info *fi, const struct fib_info *ofi)
 264 {
 265         const struct fib_nh *onh = ofi->fib_nh;
 266
 267         for_nexthops(fi) {
 268                 if (nh->nh_oif != onh->nh_oif ||
 269                     nh->nh_gw  != onh->nh_gw ||
 270                     nh->nh_scope != onh->nh_scope ||
 271 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 272                     nh->nh_weight != onh->nh_weight ||
 273 #endif
 274 #ifdef CONFIG_IP_ROUTE_CLASSID
 275                     nh->nh_tclassid != onh->nh_tclassid ||
 276 #endif
 277                     lwtunnel_cmp_encap(nh->nh_lwtstate, onh->nh_lwtstate) ||
 278                     ((nh->nh_flags ^ onh->nh_flags) & ~RTNH_COMPARE_MASK))
 279                         return -1;
 280                 onh++;
 281         } endfor_nexthops(fi);
 282         return 0;
 283 }
 284
 285 static inline unsigned int fib_devindex_hashfn(unsigned int val)
 286 {
 287         unsigned int mask = DEVINDEX_HASHSIZE - 1;
 288
 289         return (val ^
 290                 (val >> DEVINDEX_HASHBITS) ^
 291                 (val >> (DEVINDEX_HASHBITS * 2))) & mask;
 292 }
 293
 294 static inline unsigned int fib_info_hashfn(const struct fib_info *fi)
 295 {
 296         unsigned int mask = (fib_info_hash_size - 1);
 297         unsigned int val = fi->fib_nhs;
 298
 299         val ^= (fi->fib_protocol << 8) | fi->fib_scope;
 300         val ^= (__force u32)fi->fib_prefsrc;
 301         val ^= fi->fib_priority;
 302         for_nexthops(fi) {
 303                 val ^= fib_devindex_hashfn(nh->nh_oif);
 304         } endfor_nexthops(fi)
 305
 306         return (val ^ (val >> 7) ^ (val >> 12)) & mask;
 307 }
 308
 309 static struct fib_info *fib_find_info(const struct fib_info *nfi)
 310 {
 311         struct hlist_head *head;
 312         struct fib_info *fi;
 313         unsigned int hash;
 314
 315         hash = fib_info_hashfn(nfi);
 316         head = &fib_info_hash[hash];
 317
 318         hlist_for_each_entry(fi, head, fib_hash) {
 319                 if (!net_eq(fi->fib_net, nfi->fib_net))
 320                         continue;
 321                 if (fi->fib_nhs != nfi->fib_nhs)
 322                         continue;
 323                 if (nfi->fib_protocol == fi->fib_protocol &&
 324                     nfi->fib_scope == fi->fib_scope &&
 325                     nfi->fib_prefsrc == fi->fib_prefsrc &&
 326                     nfi->fib_priority == fi->fib_priority &&
 327                     nfi->fib_type == fi->fib_type &&
 328                     memcmp(nfi->fib_metrics, fi->fib_metrics,
 329                            sizeof(u32) * RTAX_MAX) == 0 &&
 330                     !((nfi->fib_flags ^ fi->fib_flags) & ~RTNH_COMPARE_MASK) &&
 331                     (nfi->fib_nhs == 0 || nh_comp(fi, nfi) == 0))
 332                         return fi;
 333         }
 334
 335         return NULL;
 336 }
 337
 338 /* Check, that the gateway is already configured.
 339  * Used only by redirect accept routine.
 340  */
 341 int ip_fib_check_default(__be32 gw, struct net_device *dev)
 342 {
 343         struct hlist_head *head;
 344         struct fib_nh *nh;
 345         unsigned int hash;
 346
 347         spin_lock(&fib_info_lock);
 348
 349         hash = fib_devindex_hashfn(dev->ifindex);
 350         head = &fib_info_devhash[hash];
 351         hlist_for_each_entry(nh, head, nh_hash) {
 352                 if (nh->nh_dev == dev &&
 353                     nh->nh_gw == gw &&
 354                     !(nh->nh_flags & RTNH_F_DEAD)) {
 355                         spin_unlock(&fib_info_lock);
 356                         return 0;
 357                 }
 358         }
 359
 360         spin_unlock(&fib_info_lock);
 361
 362         return -1;
 363 }
 364
 365 static inline size_t fib_nlmsg_size(struct fib_info *fi)
 366 {
 367         size_t payload = NLMSG_ALIGN(sizeof(struct rtmsg))
 368                          + nla_total_size(4) /* RTA_TABLE */
 369                          + nla_total_size(4) /* RTA_DST */
 370                          + nla_total_size(4) /* RTA_PRIORITY */
 371                          + nla_total_size(4) /* RTA_PREFSRC */
 372                          + nla_total_size(TCP_CA_NAME_MAX); /* RTAX_CC_ALGO */
 373
 374         /* space for nested metrics */
 375         payload += nla_total_size((RTAX_MAX * nla_total_size(4)));
 376
 377         if (fi->fib_nhs) {
 378                 size_t nh_encapsize = 0;
 379                 /* Also handles the special case fib_nhs == 1 */
 380
 381                 /* each nexthop is packed in an attribute */
 382                 size_t nhsize = nla_total_size(sizeof(struct rtnexthop));
 383
 384                 /* may contain flow and gateway attribute */
 385                 nhsize += 2 * nla_total_size(4);
 386
 387                 /* grab encap info */
 388                 for_nexthops(fi) {
 389                         if (nh->nh_lwtstate) {
 390                                 /* RTA_ENCAP_TYPE */
 391                                 nh_encapsize += lwtunnel_get_encap_size(
 392                                                 nh->nh_lwtstate);
 393                                 /* RTA_ENCAP */
 394                                 nh_encapsize +=  nla_total_size(2);
 395                         }
 396                 } endfor_nexthops(fi);
 397
 398                 /* all nexthops are packed in a nested attribute */
 399                 payload += nla_total_size((fi->fib_nhs * nhsize) +
 400                                           nh_encapsize);
 401
 402         }
 403
 404         return payload;
 405 }
 406
 407 void rtmsg_fib(int event, __be32 key, struct fib_alias *fa,
 408                int dst_len, u32 tb_id, const struct nl_info *info,
 409                unsigned int nlm_flags)
 410 {
 411         struct sk_buff *skb;
 412         u32 seq = info->nlh ? info->nlh->nlmsg_seq : 0;
 413         int err = -ENOBUFS;
 414
 415         skb = nlmsg_new(fib_nlmsg_size(fa->fa_info), GFP_KERNEL);
 416         if (!skb)
 417                 goto errout;
 418
 419         err = fib_dump_info(skb, info->portid, seq, event, tb_id,
 420                             fa->fa_type, key, dst_len,
 421                             fa->fa_tos, fa->fa_info, nlm_flags);
 422         if (err < 0) {
 423                 /* -EMSGSIZE implies BUG in fib_nlmsg_size() */
 424                 WARN_ON(err == -EMSGSIZE);
 425                 kfree_skb(skb);
 426                 goto errout;
 427         }
 428         rtnl_notify(skb, info->nl_net, info->portid, RTNLGRP_IPV4_ROUTE,
 429                     info->nlh, GFP_KERNEL);
 430         return;
 431 errout:
 432         if (err < 0)
 433                 rtnl_set_sk_err(info->nl_net, RTNLGRP_IPV4_ROUTE, err);
 434 }
 435
 436 static int fib_detect_death(struct fib_info *fi, int order,
 437                             struct fib_info **last_resort, int *last_idx,
 438                             int dflt)
 439 {
 440         struct neighbour *n;
 441         int state = NUD_NONE;
 442
 443         n = neigh_lookup(&arp_tbl, &fi->fib_nh[0].nh_gw, fi->fib_dev);
 444         if (n) {
 445                 state = n->nud_state;
 446                 neigh_release(n);
 447         } else {
 448                 return 0;
 449         }
 450         if (state == NUD_REACHABLE)
 451                 return 0;
 452         if ((state & NUD_VALID) && order != dflt)
 453                 return 0;
 454         if ((state & NUD_VALID) ||
 455             (*last_idx < 0 && order > dflt && state != NUD_INCOMPLETE)) {
 456                 *last_resort = fi;
 457                 *last_idx = order;
 458         }
 459         return 1;
 460 }
 461
 462 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 463
 464 static int fib_count_nexthops(struct rtnexthop *rtnh, int remaining,
 465                               struct netlink_ext_ack *extack)
 466 {
 467         int nhs = 0;
 468
 469         while (rtnh_ok(rtnh, remaining)) {
 470                 nhs++;
 471                 rtnh = rtnh_next(rtnh, &remaining);
 472         }
 473
 474         /* leftover implies invalid nexthop configuration, discard it */
 475         if (remaining > 0) {
 476                 NL_SET_ERR_MSG(extack,
 477                                "Invalid nexthop configuration - extra data after nexthops");
 478                 nhs = 0;
 479         }
 480
 481         return nhs;
 482 }
 483
 484 static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh,
 485                        int remaining, struct fib_config *cfg,
 486                        struct netlink_ext_ack *extack)
 487 {
 488         int ret;
 489
 490         change_nexthops(fi) {
 491                 int attrlen;
 492
 493                 if (!rtnh_ok(rtnh, remaining)) {
 494                         NL_SET_ERR_MSG(extack,
 495                                        "Invalid nexthop configuration - extra data after nexthop");
 496                         return -EINVAL;
 497                 }
 498
 499                 if (rtnh->rtnh_flags & (RTNH_F_DEAD | RTNH_F_LINKDOWN)) {
 500                         NL_SET_ERR_MSG(extack,
 501                                        "Invalid flags for nexthop - can not contain DEAD or LINKDOWN");
 502                         return -EINVAL;
 503                 }
 504
 505                 nexthop_nh->nh_flags =
 506                         (cfg->fc_flags & ~0xFF) | rtnh->rtnh_flags;
 507                 nexthop_nh->nh_oif = rtnh->rtnh_ifindex;
 508                 nexthop_nh->nh_weight = rtnh->rtnh_hops + 1;
 509
 510                 attrlen = rtnh_attrlen(rtnh);
 511                 if (attrlen > 0) {
 512                         struct nlattr *nla, *attrs = rtnh_attrs(rtnh);
 513
 514                         nla = nla_find(attrs, attrlen, RTA_GATEWAY);
 515                         nexthop_nh->nh_gw = nla ? nla_get_in_addr(nla) : 0;
 516 #ifdef CONFIG_IP_ROUTE_CLASSID
 517                         nla = nla_find(attrs, attrlen, RTA_FLOW);
 518                         nexthop_nh->nh_tclassid = nla ? nla_get_u32(nla) : 0;
 519                         if (nexthop_nh->nh_tclassid)
 520                                 fi->fib_net->ipv4.fib_num_tclassid_users++;
 521 #endif
 522                         nla = nla_find(attrs, attrlen, RTA_ENCAP);
 523                         if (nla) {
 524                                 struct lwtunnel_state *lwtstate;
 525                                 struct nlattr *nla_entype;
 526
 527                                 nla_entype = nla_find(attrs, attrlen,
 528                                                       RTA_ENCAP_TYPE);
 529                                 if (!nla_entype) {
 530                                         NL_SET_BAD_ATTR(extack, nla);
 531                                         NL_SET_ERR_MSG(extack,
 532                                                        "Encap type is missing");
 533                                         goto err_inval;
 534                                 }
 535
 536                                 ret = lwtunnel_build_state(nla_get_u16(
 537                                                            nla_entype),
 538                                                            nla,  AF_INET, cfg,
 539                                                            &lwtstate, extack);
 540                                 if (ret)
 541                                         goto errout;
 542                                 nexthop_nh->nh_lwtstate =
 543                                         lwtstate_get(lwtstate);
 544                         }
 545                 }
 546
 547                 rtnh = rtnh_next(rtnh, &remaining);
 548         } endfor_nexthops(fi);
 549
 550         return 0;
 551
 552 err_inval:
 553         ret = -EINVAL;
 554
 555 errout:
 556         return ret;
 557 }
 558
 559 static void fib_rebalance(struct fib_info *fi)
 560 {
 561         int total;
 562         int w;
 563         struct in_device *in_dev;
 564
 565         if (fi->fib_nhs < 2)
 566                 return;
 567
 568         total = 0;
 569         for_nexthops(fi) {
 570                 if (nh->nh_flags & RTNH_F_DEAD)
 571                         continue;
 572
 573                 in_dev = __in_dev_get_rtnl(nh->nh_dev);
 574
 575                 if (in_dev &&
 576                     IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev) &&
 577                     nh->nh_flags & RTNH_F_LINKDOWN)
 578                         continue;
 579
 580                 total += nh->nh_weight;
 581         } endfor_nexthops(fi);
 582
 583         w = 0;
 584         change_nexthops(fi) {
 585                 int upper_bound;
 586
 587                 in_dev = __in_dev_get_rtnl(nexthop_nh->nh_dev);
 588
 589                 if (nexthop_nh->nh_flags & RTNH_F_DEAD) {
 590                         upper_bound = -1;
 591                 } else if (in_dev &&
 592                            IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev) &&
 593                            nexthop_nh->nh_flags & RTNH_F_LINKDOWN) {
 594                         upper_bound = -1;
 595                 } else {
 596                         w += nexthop_nh->nh_weight;
 597                         upper_bound = DIV_ROUND_CLOSEST_ULL((u64)w << 31,
 598                                                             total) - 1;
 599                 }
 600
 601                 atomic_set(&nexthop_nh->nh_upper_bound, upper_bound);
 602         } endfor_nexthops(fi);
 603 }
 604
 605 static inline void fib_add_weight(struct fib_info *fi,
 606                                   const struct fib_nh *nh)
 607 {
 608         fi->fib_weight += nh->nh_weight;
 609 }
 610
 611 #else /* CONFIG_IP_ROUTE_MULTIPATH */
 612
 613 #define fib_rebalance(fi) do { } while (0)
 614 #define fib_add_weight(fi, nh) do { } while (0)
 615
 616 #endif /* CONFIG_IP_ROUTE_MULTIPATH */
 617
 618 static int fib_encap_match(u16 encap_type,
 619                            struct nlattr *encap,
 620                            const struct fib_nh *nh,
 621                            const struct fib_config *cfg,
 622                            struct netlink_ext_ack *extack)
 623 {
 624         struct lwtunnel_state *lwtstate;
 625         int ret, result = 0;
 626
 627         if (encap_type == LWTUNNEL_ENCAP_NONE)
 628                 return 0;
 629
 630         ret = lwtunnel_build_state(encap_type, encap, AF_INET,
 631                                    cfg, &lwtstate, extack);
 632         if (!ret) {
 633                 result = lwtunnel_cmp_encap(lwtstate, nh->nh_lwtstate);
 634                 lwtstate_free(lwtstate);
 635         }
 636
 637         return result;
 638 }
 639
 640 int fib_nh_match(struct fib_config *cfg, struct fib_info *fi,
 641                  struct netlink_ext_ack *extack)
 642 {
 643 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 644         struct rtnexthop *rtnh;
 645         int remaining;
 646 #endif
 647
 648         if (cfg->fc_priority && cfg->fc_priority != fi->fib_priority)
 649                 return 1;
 650
 651         if (cfg->fc_oif || cfg->fc_gw) {
 652                 if (cfg->fc_encap) {
 653                         if (fib_encap_match(cfg->fc_encap_type, cfg->fc_encap,
 654                                             fi->fib_nh, cfg, extack))
 655                                 return 1;
 656                 }
 657 #ifdef CONFIG_IP_ROUTE_CLASSID
 658                 if (cfg->fc_flow &&
 659                     cfg->fc_flow != fi->fib_nh->nh_tclassid)
 660                         return 1;
 661 #endif
 662                 if ((!cfg->fc_oif || cfg->fc_oif == fi->fib_nh->nh_oif) &&
 663                     (!cfg->fc_gw  || cfg->fc_gw == fi->fib_nh->nh_gw))
 664                         return 0;
 665                 return 1;
 666         }
 667
 668 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 669         if (!cfg->fc_mp)
 670                 return 0;
 671
 672         rtnh = cfg->fc_mp;
 673         remaining = cfg->fc_mp_len;
 674
 675         for_nexthops(fi) {
 676                 int attrlen;
 677
 678                 if (!rtnh_ok(rtnh, remaining))
 679                         return -EINVAL;
 680
 681                 if (rtnh->rtnh_ifindex && rtnh->rtnh_ifindex != nh->nh_oif)
 682                         return 1;
 683
 684                 attrlen = rtnh_attrlen(rtnh);
 685                 if (attrlen > 0) {
 686                         struct nlattr *nla, *attrs = rtnh_attrs(rtnh);
 687
 688                         nla = nla_find(attrs, attrlen, RTA_GATEWAY);
 689                         if (nla && nla_get_in_addr(nla) != nh->nh_gw)
 690                                 return 1;
 691 #ifdef CONFIG_IP_ROUTE_CLASSID
 692                         nla = nla_find(attrs, attrlen, RTA_FLOW);
 693                         if (nla && nla_get_u32(nla) != nh->nh_tclassid)
 694                                 return 1;
 695 #endif
 696                 }
 697
 698                 rtnh = rtnh_next(rtnh, &remaining);
 699         } endfor_nexthops(fi);
 700 #endif
 701         return 0;
 702 }
 703
 704 bool fib_metrics_match(struct fib_config *cfg, struct fib_info *fi)
 705 {
 706         struct nlattr *nla;
 707         int remaining;
 708
 709         if (!cfg->fc_mx)
 710                 return true;
 711
 712         nla_for_each_attr(nla, cfg->fc_mx, cfg->fc_mx_len, remaining) {
 713                 int type = nla_type(nla);
 714                 u32 fi_val, val;
 715
 716                 if (!type)
 717                         continue;
 718                 if (type > RTAX_MAX)
 719                         return false;
 720
 721                 if (type == RTAX_CC_ALGO) {
 722                         char tmp[TCP_CA_NAME_MAX];
 723                         bool ecn_ca = false;
 724
 725                         nla_strlcpy(tmp, nla, sizeof(tmp));
 726                         val = tcp_ca_get_key_by_name(tmp, &ecn_ca);
 727                 } else {
 728                         if (nla_len(nla) != sizeof(u32))
 729                                 return false;
 730                         val = nla_get_u32(nla);
 731                 }
 732
 733                 fi_val = fi->fib_metrics->metrics[type - 1];
 734                 if (type == RTAX_FEATURES)
 735                         fi_val &= ~DST_FEATURE_ECN_CA;
 736
 737                 if (fi_val != val)
 738                         return false;
 739         }
 740
 741         return true;
 742 }
 743
 744
 745 /*
 746  * Picture
 747  * -------
 748  *
 749  * Semantics of nexthop is very messy by historical reasons.
 750  * We have to take into account, that:
 751  * a) gateway can be actually local interface address,
 752  *    so that gatewayed route is direct.
 753  * b) gateway must be on-link address, possibly
 754  *    described not by an ifaddr, but also by a direct route.
 755  * c) If both gateway and interface are specified, they should not
 756  *    contradict.
 757  * d) If we use tunnel routes, gateway could be not on-link.
 758  *
 759  * Attempt to reconcile all of these (alas, self-contradictory) conditions
 760  * results in pretty ugly and hairy code with obscure logic.
 761  *
 762  * I chose to generalized it instead, so that the size
 763  * of code does not increase practically, but it becomes
 764  * much more general.
 765  * Every prefix is assigned a "scope" value: "host" is local address,
 766  * "link" is direct route,
 767  * [ ... "site" ... "interior" ... ]
 768  * and "universe" is true gateway route with global meaning.
 769  *
 770  * Every prefix refers to a set of "nexthop"s (gw, oif),
 771  * where gw must have narrower scope. This recursion stops
 772  * when gw has LOCAL scope or if "nexthop" is declared ONLINK,
 773  * which means that gw is forced to be on link.
 774  *
 775  * Code is still hairy, but now it is apparently logically
 776  * consistent and very flexible. F.e. as by-product it allows
 777  * to co-exists in peace independent exterior and interior
 778  * routing processes.
 779  *
 780  * Normally it looks as following.
 781  *
 782  * {universe prefix}  -> (gw, oif) [scope link]
 783  *                |
 784  *                |-> {link prefix} -> (gw, oif) [scope local]
 785  *                                      |
 786  *                                      |-> {local prefix} (terminal node)
 787  */
 788 static int fib_check_nh(struct fib_config *cfg, struct fib_info *fi,
 789                         struct fib_nh *nh, struct netlink_ext_ack *extack)
 790 {
 791         int err = 0;
 792         struct net *net;
 793         struct net_device *dev;
 794
 795         net = cfg->fc_nlinfo.nl_net;
 796         if (nh->nh_gw) {
 797                 struct fib_result res;
 798
 799                 if (nh->nh_flags & RTNH_F_ONLINK) {
 800                         unsigned int addr_type;
 801
 802                         if (cfg->fc_scope >= RT_SCOPE_LINK) {
 803                                 NL_SET_ERR_MSG(extack,
 804                                                "Nexthop has invalid scope");
 805                                 return -EINVAL;
 806                         }
 807                         dev = __dev_get_by_index(net, nh->nh_oif);
 808                         if (!dev)
 809                                 return -ENODEV;
 810                         if (!(dev->flags & IFF_UP)) {
 811                                 NL_SET_ERR_MSG(extack,
 812                                                "Nexthop device is not up");
 813                                 return -ENETDOWN;
 814                         }
 815                         addr_type = inet_addr_type_dev_table(net, dev, nh->nh_gw);
 816                         if (addr_type != RTN_UNICAST) {
 817                                 NL_SET_ERR_MSG(extack,
 818                                                "Nexthop has invalid gateway");
 819                                 return -EINVAL;
 820                         }
 821                         if (!netif_carrier_ok(dev))
 822                                 nh->nh_flags |= RTNH_F_LINKDOWN;
 823                         nh->nh_dev = dev;
 824                         dev_hold(dev);
 825                         nh->nh_scope = RT_SCOPE_LINK;
 826                         return 0;
 827                 }
 828                 rcu_read_lock();
 829                 {
 830                         struct fib_table *tbl = NULL;
 831                         struct flowi4 fl4 = {
 832                                 .daddr = nh->nh_gw,
 833                                 .flowi4_scope = cfg->fc_scope + 1,
 834                                 .flowi4_oif = nh->nh_oif,
 835                                 .flowi4_iif = LOOPBACK_IFINDEX,
 836                         };
 837
 838                         /* It is not necessary, but requires a bit of thinking */
 839                         if (fl4.flowi4_scope < RT_SCOPE_LINK)
 840                                 fl4.flowi4_scope = RT_SCOPE_LINK;
 841
 842                         if (cfg->fc_table && cfg->fc_table != RT_TABLE_MAIN)
 843                                 tbl = fib_get_table(net, cfg->fc_table);
 844
 845                         if (tbl)
 846                                 err = fib_table_lookup(tbl, &fl4, &res,
 847                                                        FIB_LOOKUP_IGNORE_LINKSTATE |
 848                                                        FIB_LOOKUP_NOREF);
 849
 850                         /* on error or if no table given do full lookup. This
 851                          * is needed for example when nexthops are in the local
 852                          * table rather than the given table
 853                          */
 854                         if (!tbl || err) {
 855                                 err = fib_lookup(net, &fl4, &res,
 856                                                  FIB_LOOKUP_IGNORE_LINKSTATE);
 857                         }
 858
 859                         if (err) {
 860                                 NL_SET_ERR_MSG(extack,
 861                                                "Nexthop has invalid gateway");
 862                                 rcu_read_unlock();
 863                                 return err;
 864                         }
 865                 }
 866                 err = -EINVAL;
 867                 if (res.type != RTN_UNICAST && res.type != RTN_LOCAL) {
 868                         NL_SET_ERR_MSG(extack, "Nexthop has invalid gateway");
 869                         goto out;
 870                 }
 871                 nh->nh_scope = res.scope;
 872                 nh->nh_oif = FIB_RES_OIF(res);
 873                 nh->nh_dev = dev = FIB_RES_DEV(res);
 874                 if (!dev) {
 875                         NL_SET_ERR_MSG(extack,
 876                                        "No egress device for nexthop gateway");
 877                         goto out;
 878                 }
 879                 dev_hold(dev);
 880                 if (!netif_carrier_ok(dev))
 881                         nh->nh_flags |= RTNH_F_LINKDOWN;
 882                 err = (dev->flags & IFF_UP) ? 0 : -ENETDOWN;
 883         } else {
 884                 struct in_device *in_dev;
 885
 886                 if (nh->nh_flags & (RTNH_F_PERVASIVE | RTNH_F_ONLINK)) {
 887                         NL_SET_ERR_MSG(extack,
 888                                        "Invalid flags for nexthop - PERVASIVE and ONLINK can not be set");
 889                         return -EINVAL;
 890                 }
 891                 rcu_read_lock();
 892                 err = -ENODEV;
 893                 in_dev = inetdev_by_index(net, nh->nh_oif);
 894                 if (!in_dev)
 895                         goto out;
 896                 err = -ENETDOWN;
 897                 if (!(in_dev->dev->flags & IFF_UP)) {
 898                         NL_SET_ERR_MSG(extack, "Device for nexthop is not up");
 899                         goto out;
 900                 }
 901                 nh->nh_dev = in_dev->dev;
 902                 dev_hold(nh->nh_dev);
 903                 nh->nh_scope = RT_SCOPE_HOST;
 904                 if (!netif_carrier_ok(nh->nh_dev))
 905                         nh->nh_flags |= RTNH_F_LINKDOWN;
 906                 err = 0;
 907         }
 908 out:
 909         rcu_read_unlock();
 910         return err;
 911 }
 912
 913 static inline unsigned int fib_laddr_hashfn(__be32 val)
 914 {
 915         unsigned int mask = (fib_info_hash_size - 1);
 916
 917         return ((__force u32)val ^
 918                 ((__force u32)val >> 7) ^
 919                 ((__force u32)val >> 14)) & mask;
 920 }
 921
 922 static struct hlist_head *fib_info_hash_alloc(int bytes)
 923 {
 924         if (bytes <= PAGE_SIZE)
 925                 return kzalloc(bytes, GFP_KERNEL);
 926         else
 927                 return (struct hlist_head *)
 928                         __get_free_pages(GFP_KERNEL | __GFP_ZERO,
 929                                          get_order(bytes));
 930 }
 931
 932 static void fib_info_hash_free(struct hlist_head *hash, int bytes)
 933 {
 934         if (!hash)
 935                 return;
 936
 937         if (bytes <= PAGE_SIZE)
 938                 kfree(hash);
 939         else
 940                 free_pages((unsigned long) hash, get_order(bytes));
 941 }
 942
 943 static void fib_info_hash_move(struct hlist_head *new_info_hash,
 944                                struct hlist_head *new_laddrhash,
 945                                unsigned int new_size)
 946 {
 947         struct hlist_head *old_info_hash, *old_laddrhash;
 948         unsigned int old_size = fib_info_hash_size;
 949         unsigned int i, bytes;
 950
 951         spin_lock_bh(&fib_info_lock);
 952         old_info_hash = fib_info_hash;
 953         old_laddrhash = fib_info_laddrhash;
 954         fib_info_hash_size = new_size;
 955
 956         for (i = 0; i < old_size; i++) {
 957                 struct hlist_head *head = &fib_info_hash[i];
 958                 struct hlist_node *n;
 959                 struct fib_info *fi;
 960
 961                 hlist_for_each_entry_safe(fi, n, head, fib_hash) {
 962                         struct hlist_head *dest;
 963                         unsigned int new_hash;
 964
 965                         new_hash = fib_info_hashfn(fi);
 966                         dest = &new_info_hash[new_hash];
 967                         hlist_add_head(&fi->fib_hash, dest);
 968                 }
 969         }
 970         fib_info_hash = new_info_hash;
 971
 972         for (i = 0; i < old_size; i++) {
 973                 struct hlist_head *lhead = &fib_info_laddrhash[i];
 974                 struct hlist_node *n;
 975                 struct fib_info *fi;
 976
 977                 hlist_for_each_entry_safe(fi, n, lhead, fib_lhash) {
 978                         struct hlist_head *ldest;
 979                         unsigned int new_hash;
 980
 981                         new_hash = fib_laddr_hashfn(fi->fib_prefsrc);
 982                         ldest = &new_laddrhash[new_hash];
 983                         hlist_add_head(&fi->fib_lhash, ldest);
 984                 }
 985         }
 986         fib_info_laddrhash = new_laddrhash;
 987
 988         spin_unlock_bh(&fib_info_lock);
 989
 990         bytes = old_size * sizeof(struct hlist_head *);
 991         fib_info_hash_free(old_info_hash, bytes);
 992         fib_info_hash_free(old_laddrhash, bytes);
 993 }
 994
 995 __be32 fib_info_update_nh_saddr(struct net *net, struct fib_nh *nh)
 996 {
 997         nh->nh_saddr = inet_select_addr(nh->nh_dev,
 998                                         nh->nh_gw,
 999                                         nh->nh_parent->fib_scope);
1000         nh->nh_saddr_genid = atomic_read(&net->ipv4.dev_addr_genid);
1001
1002         return nh->nh_saddr;
1003 }
1004
1005 static bool fib_valid_prefsrc(struct fib_config *cfg, __be32 fib_prefsrc)
1006 {
1007         if (cfg->fc_type != RTN_LOCAL || !cfg->fc_dst ||
1008             fib_prefsrc != cfg->fc_dst) {
1009                 u32 tb_id = cfg->fc_table;
1010                 int rc;
1011
1012                 if (tb_id == RT_TABLE_MAIN)
1013                         tb_id = RT_TABLE_LOCAL;
1014
1015                 rc = inet_addr_type_table(cfg->fc_nlinfo.nl_net,
1016                                           fib_prefsrc, tb_id);
1017
1018                 if (rc != RTN_LOCAL && tb_id != RT_TABLE_LOCAL) {
1019                         rc = inet_addr_type_table(cfg->fc_nlinfo.nl_net,
1020                                                   fib_prefsrc, RT_TABLE_LOCAL);
1021                 }
1022
1023                 if (rc != RTN_LOCAL)
1024                         return false;
1025         }
1026         return true;
1027 }
1028
1029 static int
1030 fib_convert_metrics(struct fib_info *fi, const struct fib_config *cfg)
1031 {
1032         bool ecn_ca = false;
1033         struct nlattr *nla;
1034         int remaining;
1035
1036         if (!cfg->fc_mx)
1037                 return 0;
1038
1039         nla_for_each_attr(nla, cfg->fc_mx, cfg->fc_mx_len, remaining) {
1040                 int type = nla_type(nla);
1041                 u32 val;
1042
1043                 if (!type)
1044                         continue;
1045                 if (type > RTAX_MAX)
1046                         return -EINVAL;
1047
1048                 if (type == RTAX_CC_ALGO) {
1049                         char tmp[TCP_CA_NAME_MAX];
1050
1051                         nla_strlcpy(tmp, nla, sizeof(tmp));
1052                         val = tcp_ca_get_key_by_name(tmp, &ecn_ca);
1053                         if (val == TCP_CA_UNSPEC)
1054                                 return -EINVAL;
1055                 } else {
1056                         if (nla_len(nla) != sizeof(u32))
1057                                 return -EINVAL;
1058                         val = nla_get_u32(nla);
1059                 }
1060                 if (type == RTAX_ADVMSS && val > 65535 - 40)
1061                         val = 65535 - 40;
1062                 if (type == RTAX_MTU && val > 65535 - 15)
1063                         val = 65535 - 15;
1064                 if (type == RTAX_HOPLIMIT && val > 255)
1065                         val = 255;
1066                 if (type == RTAX_FEATURES && (val & ~RTAX_FEATURE_MASK))
1067                         return -EINVAL;
1068                 fi->fib_metrics->metrics[type - 1] = val;
1069         }
1070
1071         if (ecn_ca)
1072                 fi->fib_metrics->metrics[RTAX_FEATURES - 1] |= DST_FEATURE_ECN_CA;
1073
1074         return 0;
1075 }
1076
1077 struct fib_info *fib_create_info(struct fib_config *cfg,
1078                                  struct netlink_ext_ack *extack)
1079 {
1080         int err;
1081         struct fib_info *fi = NULL;
1082         struct fib_info *ofi;
1083         int nhs = 1;
1084         struct net *net = cfg->fc_nlinfo.nl_net;
1085
1086         if (cfg->fc_type > RTN_MAX)
1087                 goto err_inval;
1088
1089         /* Fast check to catch the most weird cases */
1090         if (fib_props[cfg->fc_type].scope > cfg->fc_scope) {
1091                 NL_SET_ERR_MSG(extack, "Invalid scope");
1092                 goto err_inval;
1093         }
1094
1095         if (cfg->fc_flags & (RTNH_F_DEAD | RTNH_F_LINKDOWN)) {
1096                 NL_SET_ERR_MSG(extack,
1097                                "Invalid rtm_flags - can not contain DEAD or LINKDOWN");
1098                 goto err_inval;
1099         }
1100
1101 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1102         if (cfg->fc_mp) {
1103                 nhs = fib_count_nexthops(cfg->fc_mp, cfg->fc_mp_len, extack);
1104                 if (nhs == 0)
1105                         goto err_inval;
1106         }
1107 #endif
1108
1109         err = -ENOBUFS;
1110         if (fib_info_cnt >= fib_info_hash_size) {
1111                 unsigned int new_size = fib_info_hash_size << 1;
1112                 struct hlist_head *new_info_hash;
1113                 struct hlist_head *new_laddrhash;
1114                 unsigned int bytes;
1115
1116                 if (!new_size)
1117                         new_size = 16;
1118                 bytes = new_size * sizeof(struct hlist_head *);
1119                 new_info_hash = fib_info_hash_alloc(bytes);
1120                 new_laddrhash = fib_info_hash_alloc(bytes);
1121                 if (!new_info_hash || !new_laddrhash) {
1122                         fib_info_hash_free(new_info_hash, bytes);
1123                         fib_info_hash_free(new_laddrhash, bytes);
1124                 } else
1125                         fib_info_hash_move(new_info_hash, new_laddrhash, new_size);
1126
1127                 if (!fib_info_hash_size)
1128                         goto failure;
1129         }
1130
1131         fi = kzalloc(sizeof(*fi)+nhs*sizeof(struct fib_nh), GFP_KERNEL);
1132         if (!fi)
1133                 goto failure;
1134         if (cfg->fc_mx) {
1135                 fi->fib_metrics = kzalloc(sizeof(*fi->fib_metrics), GFP_KERNEL);
1136                 if (unlikely(!fi->fib_metrics)) {
1137                         kfree(fi);
1138                         return ERR_PTR(err);
1139                 }
1140                 refcount_set(&fi->fib_metrics->refcnt, 1);
1141         } else {
1142                 fi->fib_metrics = (struct dst_metrics *)&dst_default_metrics;
1143         }
1144         fib_info_cnt++;
1145         fi->fib_net = net;
1146         fi->fib_protocol = cfg->fc_protocol;
1147         fi->fib_scope = cfg->fc_scope;
1148         fi->fib_flags = cfg->fc_flags;
1149         fi->fib_priority = cfg->fc_priority;
1150         fi->fib_prefsrc = cfg->fc_prefsrc;
1151         fi->fib_type = cfg->fc_type;
1152         fi->fib_tb_id = cfg->fc_table;
1153
1154         fi->fib_nhs = nhs;
1155         change_nexthops(fi) {
1156                 nexthop_nh->nh_parent = fi;
1157                 nexthop_nh->nh_pcpu_rth_output = alloc_percpu(struct rtable __rcu *);
1158                 if (!nexthop_nh->nh_pcpu_rth_output)
1159                         goto failure;
1160         } endfor_nexthops(fi)
1161
1162         err = fib_convert_metrics(fi, cfg);
1163         if (err)
1164                 goto failure;
1165
1166         if (cfg->fc_mp) {
1167 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1168                 err = fib_get_nhs(fi, cfg->fc_mp, cfg->fc_mp_len, cfg, extack);
1169                 if (err != 0)
1170                         goto failure;
1171                 if (cfg->fc_oif && fi->fib_nh->nh_oif != cfg->fc_oif) {
1172                         NL_SET_ERR_MSG(extack,
1173                                        "Nexthop device index does not match RTA_OIF");
1174                         goto err_inval;
1175                 }
1176                 if (cfg->fc_gw && fi->fib_nh->nh_gw != cfg->fc_gw) {
1177                         NL_SET_ERR_MSG(extack,
1178                                        "Nexthop gateway does not match RTA_GATEWAY");
1179                         goto err_inval;
1180                 }
1181 #ifdef CONFIG_IP_ROUTE_CLASSID
1182                 if (cfg->fc_flow && fi->fib_nh->nh_tclassid != cfg->fc_flow) {
1183                         NL_SET_ERR_MSG(extack,
1184                                        "Nexthop class id does not match RTA_FLOW");
1185                         goto err_inval;
1186                 }
1187 #endif
1188 #else
1189                 NL_SET_ERR_MSG(extack,
1190                                "Multipath support not enabled in kernel");
1191                 goto err_inval;
1192 #endif
1193         } else {
1194                 struct fib_nh *nh = fi->fib_nh;
1195
1196                 if (cfg->fc_encap) {
1197                         struct lwtunnel_state *lwtstate;
1198
1199                         if (cfg->fc_encap_type == LWTUNNEL_ENCAP_NONE) {
1200                                 NL_SET_ERR_MSG(extack,
1201                                                "LWT encap type not specified");
1202                                 goto err_inval;
1203                         }
1204                         err = lwtunnel_build_state(cfg->fc_encap_type,
1205                                                    cfg->fc_encap, AF_INET, cfg,
1206                                                    &lwtstate, extack);
1207                         if (err)
1208                                 goto failure;
1209
1210                         nh->nh_lwtstate = lwtstate_get(lwtstate);
1211                 }
1212                 nh->nh_oif = cfg->fc_oif;
1213                 nh->nh_gw = cfg->fc_gw;
1214                 nh->nh_flags = cfg->fc_flags;
1215 #ifdef CONFIG_IP_ROUTE_CLASSID
1216                 nh->nh_tclassid = cfg->fc_flow;
1217                 if (nh->nh_tclassid)
1218                         fi->fib_net->ipv4.fib_num_tclassid_users++;
1219 #endif
1220 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1221                 nh->nh_weight = 1;
1222 #endif
1223         }
1224
1225         if (fib_props[cfg->fc_type].error) {
1226                 if (cfg->fc_gw || cfg->fc_oif || cfg->fc_mp) {
1227                         NL_SET_ERR_MSG(extack,
1228                                        "Gateway, device and multipath can not be specified for this route type");
1229                         goto err_inval;
1230                 }
1231                 goto link_it;
1232         } else {
1233                 switch (cfg->fc_type) {
1234                 case RTN_UNICAST:
1235                 case RTN_LOCAL:
1236                 case RTN_BROADCAST:
1237                 case RTN_ANYCAST:
1238                 case RTN_MULTICAST:
1239                         break;
1240                 default:
1241                         NL_SET_ERR_MSG(extack, "Invalid route type");
1242                         goto err_inval;
1243                 }
1244         }
1245
1246         if (cfg->fc_scope > RT_SCOPE_HOST) {
1247                 NL_SET_ERR_MSG(extack, "Invalid scope");
1248                 goto err_inval;
1249         }
1250
1251         if (cfg->fc_scope == RT_SCOPE_HOST) {
1252                 struct fib_nh *nh = fi->fib_nh;
1253
1254                 /* Local address is added. */
1255                 if (nhs != 1) {
1256                         NL_SET_ERR_MSG(extack,
1257                                        "Route with host scope can not have multiple nexthops");
1258                         goto err_inval;
1259                 }
1260                 if (nh->nh_gw) {
1261                         NL_SET_ERR_MSG(extack,
1262                                        "Route with host scope can not have a gateway");
1263                         goto err_inval;
1264                 }
1265                 nh->nh_scope = RT_SCOPE_NOWHERE;
1266                 nh->nh_dev = dev_get_by_index(net, fi->fib_nh->nh_oif);
1267                 err = -ENODEV;
1268                 if (!nh->nh_dev)
1269                         goto failure;
1270         } else {
1271                 int linkdown = 0;
1272
1273                 change_nexthops(fi) {
1274                         err = fib_check_nh(cfg, fi, nexthop_nh, extack);
1275                         if (err != 0)
1276                                 goto failure;
1277                         if (nexthop_nh->nh_flags & RTNH_F_LINKDOWN)
1278                                 linkdown++;
1279                 } endfor_nexthops(fi)
1280                 if (linkdown == fi->fib_nhs)
1281                         fi->fib_flags |= RTNH_F_LINKDOWN;
1282         }
1283
1284         if (fi->fib_prefsrc && !fib_valid_prefsrc(cfg, fi->fib_prefsrc)) {
1285                 NL_SET_ERR_MSG(extack, "Invalid prefsrc address");
1286                 goto err_inval;
1287         }
1288
1289         change_nexthops(fi) {
1290                 fib_info_update_nh_saddr(net, nexthop_nh);
1291                 fib_add_weight(fi, nexthop_nh);
1292         } endfor_nexthops(fi)
1293
1294         fib_rebalance(fi);
1295
1296 link_it:
1297         ofi = fib_find_info(fi);
1298         if (ofi) {
1299                 fi->fib_dead = 1;
1300                 free_fib_info(fi);
1301                 ofi->fib_treeref++;
1302                 return ofi;
1303         }
1304
1305         fi->fib_treeref++;
1306         refcount_set(&fi->fib_clntref, 1);
1307         spin_lock_bh(&fib_info_lock);
1308         hlist_add_head(&fi->fib_hash,
1309                        &fib_info_hash[fib_info_hashfn(fi)]);
1310         if (fi->fib_prefsrc) {
1311                 struct hlist_head *head;
1312
1313                 head = &fib_info_laddrhash[fib_laddr_hashfn(fi->fib_prefsrc)];
1314                 hlist_add_head(&fi->fib_lhash, head);
1315         }
1316         change_nexthops(fi) {
1317                 struct hlist_head *head;
1318                 unsigned int hash;
1319
1320                 if (!nexthop_nh->nh_dev)
1321                         continue;
1322                 hash = fib_devindex_hashfn(nexthop_nh->nh_dev->ifindex);
1323                 head = &fib_info_devhash[hash];
1324                 hlist_add_head(&nexthop_nh->nh_hash, head);
1325         } endfor_nexthops(fi)
1326         spin_unlock_bh(&fib_info_lock);
1327         return fi;
1328
1329 err_inval:
1330         err = -EINVAL;
1331
1332 failure:
1333         if (fi) {
1334                 fi->fib_dead = 1;
1335                 free_fib_info(fi);
1336         }
1337
1338         return ERR_PTR(err);
1339 }
1340
1341 int fib_dump_info(struct sk_buff *skb, u32 portid, u32 seq, int event,
1342                   u32 tb_id, u8 type, __be32 dst, int dst_len, u8 tos,
1343                   struct fib_info *fi, unsigned int flags)
1344 {
1345         struct nlmsghdr *nlh;
1346         struct rtmsg *rtm;
1347
1348         nlh = nlmsg_put(skb, portid, seq, event, sizeof(*rtm), flags);
1349         if (!nlh)
1350                 return -EMSGSIZE;
1351
1352         rtm = nlmsg_data(nlh);
1353         rtm->rtm_family = AF_INET;
1354         rtm->rtm_dst_len = dst_len;
1355         rtm->rtm_src_len = 0;
1356         rtm->rtm_tos = tos;
1357         if (tb_id < 256)
1358                 rtm->rtm_table = tb_id;
1359         else
1360                 rtm->rtm_table = RT_TABLE_COMPAT;
1361         if (nla_put_u32(skb, RTA_TABLE, tb_id))
1362                 goto nla_put_failure;
1363         rtm->rtm_type = type;
1364         rtm->rtm_flags = fi->fib_flags;
1365         rtm->rtm_scope = fi->fib_scope;
1366         rtm->rtm_protocol = fi->fib_protocol;
1367
1368         if (rtm->rtm_dst_len &&
1369             nla_put_in_addr(skb, RTA_DST, dst))
1370                 goto nla_put_failure;
1371         if (fi->fib_priority &&
1372             nla_put_u32(skb, RTA_PRIORITY, fi->fib_priority))
1373                 goto nla_put_failure;
1374         if (rtnetlink_put_metrics(skb, fi->fib_metrics->metrics) < 0)
1375                 goto nla_put_failure;
1376
1377         if (fi->fib_prefsrc &&
1378             nla_put_in_addr(skb, RTA_PREFSRC, fi->fib_prefsrc))
1379                 goto nla_put_failure;
1380         if (fi->fib_nhs == 1) {
1381                 if (fi->fib_nh->nh_gw &&
1382                     nla_put_in_addr(skb, RTA_GATEWAY, fi->fib_nh->nh_gw))
1383                         goto nla_put_failure;
1384                 if (fi->fib_nh->nh_oif &&
1385                     nla_put_u32(skb, RTA_OIF, fi->fib_nh->nh_oif))
1386                         goto nla_put_failure;
1387                 if (fi->fib_nh->nh_flags & RTNH_F_LINKDOWN) {
1388                         struct in_device *in_dev;
1389
1390                         rcu_read_lock();
1391                         in_dev = __in_dev_get_rcu(fi->fib_nh->nh_dev);
1392                         if (in_dev &&
1393                             IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev))
1394                                 rtm->rtm_flags |= RTNH_F_DEAD;
1395                         rcu_read_unlock();
1396                 }
1397                 if (fi->fib_nh->nh_flags & RTNH_F_OFFLOAD)
1398                         rtm->rtm_flags |= RTNH_F_OFFLOAD;
1399 #ifdef CONFIG_IP_ROUTE_CLASSID
1400                 if (fi->fib_nh[0].nh_tclassid &&
1401                     nla_put_u32(skb, RTA_FLOW, fi->fib_nh[0].nh_tclassid))
1402                         goto nla_put_failure;
1403 #endif
1404                 if (fi->fib_nh->nh_lwtstate &&
1405                     lwtunnel_fill_encap(skb, fi->fib_nh->nh_lwtstate) < 0)
1406                         goto nla_put_failure;
1407         }
1408 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1409         if (fi->fib_nhs > 1) {
1410                 struct rtnexthop *rtnh;
1411                 struct nlattr *mp;
1412
1413                 mp = nla_nest_start(skb, RTA_MULTIPATH);
1414                 if (!mp)
1415                         goto nla_put_failure;
1416
1417                 for_nexthops(fi) {
1418                         rtnh = nla_reserve_nohdr(skb, sizeof(*rtnh));
1419                         if (!rtnh)
1420                                 goto nla_put_failure;
1421
1422                         rtnh->rtnh_flags = nh->nh_flags & 0xFF;
1423                         if (nh->nh_flags & RTNH_F_LINKDOWN) {
1424                                 struct in_device *in_dev;
1425
1426                                 rcu_read_lock();
1427                                 in_dev = __in_dev_get_rcu(nh->nh_dev);
1428                                 if (in_dev &&
1429                                     IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev))
1430                                         rtnh->rtnh_flags |= RTNH_F_DEAD;
1431                                 rcu_read_unlock();
1432                         }
1433                         rtnh->rtnh_hops = nh->nh_weight - 1;
1434                         rtnh->rtnh_ifindex = nh->nh_oif;
1435
1436                         if (nh->nh_gw &&
1437                             nla_put_in_addr(skb, RTA_GATEWAY, nh->nh_gw))
1438                                 goto nla_put_failure;
1439 #ifdef CONFIG_IP_ROUTE_CLASSID
1440                         if (nh->nh_tclassid &&
1441                             nla_put_u32(skb, RTA_FLOW, nh->nh_tclassid))
1442                                 goto nla_put_failure;
1443 #endif
1444                         if (nh->nh_lwtstate &&
1445                             lwtunnel_fill_encap(skb, nh->nh_lwtstate) < 0)
1446                                 goto nla_put_failure;
1447
1448                         /* length of rtnetlink header + attributes */
1449                         rtnh->rtnh_len = nlmsg_get_pos(skb) - (void *) rtnh;
1450                 } endfor_nexthops(fi);
1451
1452                 nla_nest_end(skb, mp);
1453         }
1454 #endif
1455         nlmsg_end(skb, nlh);
1456         return 0;
1457
1458 nla_put_failure:
1459         nlmsg_cancel(skb, nlh);
1460         return -EMSGSIZE;
1461 }
1462
1463 /*
1464  * Update FIB if:
1465  * - local address disappeared -> we must delete all the entries
1466  *   referring to it.
1467  * - device went down -> we must shutdown all nexthops going via it.
1468  */
1469 int fib_sync_down_addr(struct net_device *dev, __be32 local)
1470 {
1471         int ret = 0;
1472         unsigned int hash = fib_laddr_hashfn(local);
1473         struct hlist_head *head = &fib_info_laddrhash[hash];
1474         int tb_id = l3mdev_fib_table(dev) ? : RT_TABLE_MAIN;
1475         struct net *net = dev_net(dev);
1476         struct fib_info *fi;
1477
1478         if (!fib_info_laddrhash || local == 0)
1479                 return 0;
1480
1481         hlist_for_each_entry(fi, head, fib_lhash) {
1482                 if (!net_eq(fi->fib_net, net) ||
1483                     fi->fib_tb_id != tb_id)
1484                         continue;
1485                 if (fi->fib_prefsrc == local) {
1486                         fi->fib_flags |= RTNH_F_DEAD;
1487                         ret++;
1488                 }
1489         }
1490         return ret;
1491 }
1492
1493 static int call_fib_nh_notifiers(struct fib_nh *fib_nh,
1494                                  enum fib_event_type event_type)
1495 {
1496         struct in_device *in_dev = __in_dev_get_rtnl(fib_nh->nh_dev);
1497         struct fib_nh_notifier_info info = {
1498                 .fib_nh = fib_nh,
1499         };
1500
1501         switch (event_type) {
1502         case FIB_EVENT_NH_ADD:
1503                 if (fib_nh->nh_flags & RTNH_F_DEAD)
1504                         break;
1505                 if (IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev) &&
1506                     fib_nh->nh_flags & RTNH_F_LINKDOWN)
1507                         break;
1508                 return call_fib4_notifiers(dev_net(fib_nh->nh_dev), event_type,
1509                                            &info.info);
1510         case FIB_EVENT_NH_DEL:
1511                 if ((in_dev && IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev) &&
1512                      fib_nh->nh_flags & RTNH_F_LINKDOWN) ||
1513                     (fib_nh->nh_flags & RTNH_F_DEAD))
1514                         return call_fib4_notifiers(dev_net(fib_nh->nh_dev),
1515                                                    event_type, &info.info);
1516         default:
1517                 break;
1518         }
1519
1520         return NOTIFY_DONE;
1521 }
1522
1523 /* Update the PMTU of exceptions when:
1524  * - the new MTU of the first hop becomes smaller than the PMTU
1525  * - the old MTU was the same as the PMTU, and it limited discovery of
1526  *   larger MTUs on the path. With that limit raised, we can now
1527  *   discover larger MTUs
1528  * A special case is locked exceptions, for which the PMTU is smaller
1529  * than the minimal accepted PMTU:
1530  * - if the new MTU is greater than the PMTU, don't make any change
1531  * - otherwise, unlock and set PMTU
1532  */
1533 static void nh_update_mtu(struct fib_nh *nh, u32 new, u32 orig)
1534 {
1535         struct fnhe_hash_bucket *bucket;
1536         int i;
1537
1538         bucket = rcu_dereference_protected(nh->nh_exceptions, 1);
1539         if (!bucket)
1540                 return;
1541
1542         for (i = 0; i < FNHE_HASH_SIZE; i++) {
1543                 struct fib_nh_exception *fnhe;
1544
1545                 for (fnhe = rcu_dereference_protected(bucket[i].chain, 1);
1546                      fnhe;
1547                      fnhe = rcu_dereference_protected(fnhe->fnhe_next, 1)) {
1548                         if (fnhe->fnhe_mtu_locked) {
1549                                 if (new <= fnhe->fnhe_pmtu) {
1550                                         fnhe->fnhe_pmtu = new;
1551                                         fnhe->fnhe_mtu_locked = false;
1552                                 }
1553                         } else if (new < fnhe->fnhe_pmtu ||
1554                                    orig == fnhe->fnhe_pmtu) {
1555                                 fnhe->fnhe_pmtu = new;
1556                         }
1557                 }
1558         }
1559 }
1560
1561 void fib_sync_mtu(struct net_device *dev, u32 orig_mtu)
1562 {
1563         unsigned int hash = fib_devindex_hashfn(dev->ifindex);
1564         struct hlist_head *head = &fib_info_devhash[hash];
1565         struct fib_nh *nh;
1566
1567         hlist_for_each_entry(nh, head, nh_hash) {
1568                 if (nh->nh_dev == dev)
1569                         nh_update_mtu(nh, dev->mtu, orig_mtu);
1570         }
1571 }
1572
1573 /* Event              force Flags           Description
1574  * NETDEV_CHANGE      0     LINKDOWN        Carrier OFF, not for scope host
1575  * NETDEV_DOWN        0     LINKDOWN|DEAD   Link down, not for scope host
1576  * NETDEV_DOWN        1     LINKDOWN|DEAD   Last address removed
1577  * NETDEV_UNREGISTER  1     LINKDOWN|DEAD   Device removed
1578  */
1579 int fib_sync_down_dev(struct net_device *dev, unsigned long event, bool force)
1580 {
1581         int ret = 0;
1582         int scope = RT_SCOPE_NOWHERE;
1583         struct fib_info *prev_fi = NULL;
1584         unsigned int hash = fib_devindex_hashfn(dev->ifindex);
1585         struct hlist_head *head = &fib_info_devhash[hash];
1586         struct fib_nh *nh;
1587
1588         if (force)
1589                 scope = -1;
1590
1591         hlist_for_each_entry(nh, head, nh_hash) {
1592                 struct fib_info *fi = nh->nh_parent;
1593                 int dead;
1594
1595                 BUG_ON(!fi->fib_nhs);
1596                 if (nh->nh_dev != dev || fi == prev_fi)
1597                         continue;
1598                 prev_fi = fi;
1599                 dead = 0;
1600                 change_nexthops(fi) {
1601                         if (nexthop_nh->nh_flags & RTNH_F_DEAD)
1602                                 dead++;
1603                         else if (nexthop_nh->nh_dev == dev &&
1604                                  nexthop_nh->nh_scope != scope) {
1605                                 switch (event) {
1606                                 case NETDEV_DOWN:
1607                                 case NETDEV_UNREGISTER:
1608                                         nexthop_nh->nh_flags |= RTNH_F_DEAD;
1609                                         /* fall through */
1610                                 case NETDEV_CHANGE:
1611                                         nexthop_nh->nh_flags |= RTNH_F_LINKDOWN;
1612                                         break;
1613                                 }
1614                                 call_fib_nh_notifiers(nexthop_nh,
1615                                                       FIB_EVENT_NH_DEL);
1616                                 dead++;
1617                         }
1618 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1619                         if (event == NETDEV_UNREGISTER &&
1620                             nexthop_nh->nh_dev == dev) {
1621                                 dead = fi->fib_nhs;
1622                                 break;
1623                         }
1624 #endif
1625                 } endfor_nexthops(fi)
1626                 if (dead == fi->fib_nhs) {
1627                         switch (event) {
1628                         case NETDEV_DOWN:
1629                         case NETDEV_UNREGISTER:
1630                                 fi->fib_flags |= RTNH_F_DEAD;
1631                                 /* fall through */
1632                         case NETDEV_CHANGE:
1633                                 fi->fib_flags |= RTNH_F_LINKDOWN;
1634                                 break;
1635                         }
1636                         ret++;
1637                 }
1638
1639                 fib_rebalance(fi);
1640         }
1641
1642         return ret;
1643 }
1644
1645 /* Must be invoked inside of an RCU protected region.  */
1646 static void fib_select_default(const struct flowi4 *flp, struct fib_result *res)
1647 {
1648         struct fib_info *fi = NULL, *last_resort = NULL;
1649         struct hlist_head *fa_head = res->fa_head;
1650         struct fib_table *tb = res->table;
1651         u8 slen = 32 - res->prefixlen;
1652         int order = -1, last_idx = -1;
1653         struct fib_alias *fa, *fa1 = NULL;
1654         u32 last_prio = res->fi->fib_priority;
1655         u8 last_tos = 0;
1656
1657         hlist_for_each_entry_rcu(fa, fa_head, fa_list) {
1658                 struct fib_info *next_fi = fa->fa_info;
1659
1660                 if (fa->fa_slen != slen)
1661                         continue;
1662                 if (fa->fa_tos && fa->fa_tos != flp->flowi4_tos)
1663                         continue;
1664                 if (fa->tb_id != tb->tb_id)
1665                         continue;
1666                 if (next_fi->fib_priority > last_prio &&
1667                     fa->fa_tos == last_tos) {
1668                         if (last_tos)
1669                                 continue;
1670                         break;
1671                 }
1672                 if (next_fi->fib_flags & RTNH_F_DEAD)
1673                         continue;
1674                 last_tos = fa->fa_tos;
1675                 last_prio = next_fi->fib_priority;
1676
1677                 if (next_fi->fib_scope != res->scope ||
1678                     fa->fa_type != RTN_UNICAST)
1679                         continue;
1680                 if (!next_fi->fib_nh[0].nh_gw ||
1681                     next_fi->fib_nh[0].nh_scope != RT_SCOPE_LINK)
1682                         continue;
1683
1684                 fib_alias_accessed(fa);
1685
1686                 if (!fi) {
1687                         if (next_fi != res->fi)
1688                                 break;
1689                         fa1 = fa;
1690                 } else if (!fib_detect_death(fi, order, &last_resort,
1691                                              &last_idx, fa1->fa_default)) {
1692                         fib_result_assign(res, fi);
1693                         fa1->fa_default = order;
1694                         goto out;
1695                 }
1696                 fi = next_fi;
1697                 order++;
1698         }
1699
1700         if (order <= 0 || !fi) {
1701                 if (fa1)
1702                         fa1->fa_default = -1;
1703                 goto out;
1704         }
1705
1706         if (!fib_detect_death(fi, order, &last_resort, &last_idx,
1707                               fa1->fa_default)) {
1708                 fib_result_assign(res, fi);
1709                 fa1->fa_default = order;
1710                 goto out;
1711         }
1712
1713         if (last_idx >= 0)
1714                 fib_result_assign(res, last_resort);
1715         fa1->fa_default = last_idx;
1716 out:
1717         return;
1718 }
1719
1720 /*
1721  * Dead device goes up. We wake up dead nexthops.
1722  * It takes sense only on multipath routes.
1723  */
1724 int fib_sync_up(struct net_device *dev, unsigned int nh_flags)
1725 {
1726         struct fib_info *prev_fi;
1727         unsigned int hash;
1728         struct hlist_head *head;
1729         struct fib_nh *nh;
1730         int ret;
1731
1732         if (!(dev->flags & IFF_UP))
1733                 return 0;
1734
1735         if (nh_flags & RTNH_F_DEAD) {
1736                 unsigned int flags = dev_get_flags(dev);
1737
1738                 if (flags & (IFF_RUNNING | IFF_LOWER_UP))
1739                         nh_flags |= RTNH_F_LINKDOWN;
1740         }
1741
1742         prev_fi = NULL;
1743         hash = fib_devindex_hashfn(dev->ifindex);
1744         head = &fib_info_devhash[hash];
1745         ret = 0;
1746
1747         hlist_for_each_entry(nh, head, nh_hash) {
1748                 struct fib_info *fi = nh->nh_parent;
1749                 int alive;
1750
1751                 BUG_ON(!fi->fib_nhs);
1752                 if (nh->nh_dev != dev || fi == prev_fi)
1753                         continue;
1754
1755                 prev_fi = fi;
1756                 alive = 0;
1757                 change_nexthops(fi) {
1758                         if (!(nexthop_nh->nh_flags & nh_flags)) {
1759                                 alive++;
1760                                 continue;
1761                         }
1762                         if (!nexthop_nh->nh_dev ||
1763                             !(nexthop_nh->nh_dev->flags & IFF_UP))
1764                                 continue;
1765                         if (nexthop_nh->nh_dev != dev ||
1766                             !__in_dev_get_rtnl(dev))
1767                                 continue;
1768                         alive++;
1769                         nexthop_nh->nh_flags &= ~nh_flags;
1770                         call_fib_nh_notifiers(nexthop_nh, FIB_EVENT_NH_ADD);
1771                 } endfor_nexthops(fi)
1772
1773                 if (alive > 0) {
1774                         fi->fib_flags &= ~nh_flags;
1775                         ret++;
1776                 }
1777
1778                 fib_rebalance(fi);
1779         }
1780
1781         return ret;
1782 }
1783
1784 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1785 static bool fib_good_nh(const struct fib_nh *nh)
1786 {
1787         int state = NUD_REACHABLE;
1788
1789         if (nh->nh_scope == RT_SCOPE_LINK) {
1790                 struct neighbour *n;
1791
1792                 rcu_read_lock_bh();
1793
1794                 n = __ipv4_neigh_lookup_noref(nh->nh_dev,
1795                                               (__force u32)nh->nh_gw);
1796                 if (n)
1797                         state = n->nud_state;
1798
1799                 rcu_read_unlock_bh();
1800         }
1801
1802         return !!(state & NUD_VALID);
1803 }
1804
1805 void fib_select_multipath(struct fib_result *res, int hash)
1806 {
1807         struct fib_info *fi = res->fi;
1808         struct net *net = fi->fib_net;
1809         bool first = false;
1810
1811         for_nexthops(fi) {
1812                 if (net->ipv4.sysctl_fib_multipath_use_neigh) {
1813                         if (!fib_good_nh(nh))
1814                                 continue;
1815                         if (!first) {
1816                                 res->nh_sel = nhsel;
1817                                 first = true;
1818                         }
1819                 }
1820
1821                 if (hash > atomic_read(&nh->nh_upper_bound))
1822                         continue;
1823
1824                 res->nh_sel = nhsel;
1825                 return;
1826         } endfor_nexthops(fi);
1827 }
1828 #endif
1829
1830 void fib_select_path(struct net *net, struct fib_result *res,
1831                      struct flowi4 *fl4, const struct sk_buff *skb)
1832 {
1833         bool oif_check;
1834
1835         oif_check = (fl4->flowi4_oif == 0 ||
1836                      fl4->flowi4_flags & FLOWI_FLAG_SKIP_NH_OIF);
1837
1838 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1839         if (res->fi->fib_nhs > 1 && oif_check) {
1840                 int h = fib_multipath_hash(res->fi, fl4, skb);
1841
1842                 fib_select_multipath(res, h);
1843         }
1844         else
1845 #endif
1846         if (!res->prefixlen &&
1847             res->table->tb_num_default > 1 &&
1848             res->type == RTN_UNICAST && oif_check)
1849                 fib_select_default(fl4, res);
1850
1851         if (!fl4->saddr)
1852                 fl4->saddr = FIB_RES_PREFSRC(net, *res);
1853 }
1854 EXPORT_SYMBOL_GPL(fib_select_path);