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                 if ((!cfg->fc_oif || cfg->fc_oif == fi->fib_nh->nh_oif) &&
 658                     (!cfg->fc_gw  || cfg->fc_gw == fi->fib_nh->nh_gw))
 659                         return 0;
 660                 return 1;
 661         }
 662
 663 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 664         if (!cfg->fc_mp)
 665                 return 0;
 666
 667         rtnh = cfg->fc_mp;
 668         remaining = cfg->fc_mp_len;
 669
 670         for_nexthops(fi) {
 671                 int attrlen;
 672
 673                 if (!rtnh_ok(rtnh, remaining))
 674                         return -EINVAL;
 675
 676                 if (rtnh->rtnh_ifindex && rtnh->rtnh_ifindex != nh->nh_oif)
 677                         return 1;
 678
 679                 attrlen = rtnh_attrlen(rtnh);
 680                 if (attrlen > 0) {
 681                         struct nlattr *nla, *attrs = rtnh_attrs(rtnh);
 682
 683                         nla = nla_find(attrs, attrlen, RTA_GATEWAY);
 684                         if (nla && nla_get_in_addr(nla) != nh->nh_gw)
 685                                 return 1;
 686 #ifdef CONFIG_IP_ROUTE_CLASSID
 687                         nla = nla_find(attrs, attrlen, RTA_FLOW);
 688                         if (nla && nla_get_u32(nla) != nh->nh_tclassid)
 689                                 return 1;
 690 #endif
 691                 }
 692
 693                 rtnh = rtnh_next(rtnh, &remaining);
 694         } endfor_nexthops(fi);
 695 #endif
 696         return 0;
 697 }
 698
 699 bool fib_metrics_match(struct fib_config *cfg, struct fib_info *fi)
 700 {
 701         struct nlattr *nla;
 702         int remaining;
 703
 704         if (!cfg->fc_mx)
 705                 return true;
 706
 707         nla_for_each_attr(nla, cfg->fc_mx, cfg->fc_mx_len, remaining) {
 708                 int type = nla_type(nla);
 709                 u32 val;
 710
 711                 if (!type)
 712                         continue;
 713                 if (type > RTAX_MAX)
 714                         return false;
 715
 716                 if (type == RTAX_CC_ALGO) {
 717                         char tmp[TCP_CA_NAME_MAX];
 718                         bool ecn_ca = false;
 719
 720                         nla_strlcpy(tmp, nla, sizeof(tmp));
 721                         val = tcp_ca_get_key_by_name(tmp, &ecn_ca);
 722                 } else {
 723                         val = nla_get_u32(nla);
 724                 }
 725
 726                 if (fi->fib_metrics->metrics[type - 1] != val)
 727                         return false;
 728         }
 729
 730         return true;
 731 }
 732
 733
 734 /*
 735  * Picture
 736  * -------
 737  *
 738  * Semantics of nexthop is very messy by historical reasons.
 739  * We have to take into account, that:
 740  * a) gateway can be actually local interface address,
 741  *    so that gatewayed route is direct.
 742  * b) gateway must be on-link address, possibly
 743  *    described not by an ifaddr, but also by a direct route.
 744  * c) If both gateway and interface are specified, they should not
 745  *    contradict.
 746  * d) If we use tunnel routes, gateway could be not on-link.
 747  *
 748  * Attempt to reconcile all of these (alas, self-contradictory) conditions
 749  * results in pretty ugly and hairy code with obscure logic.
 750  *
 751  * I chose to generalized it instead, so that the size
 752  * of code does not increase practically, but it becomes
 753  * much more general.
 754  * Every prefix is assigned a "scope" value: "host" is local address,
 755  * "link" is direct route,
 756  * [ ... "site" ... "interior" ... ]
 757  * and "universe" is true gateway route with global meaning.
 758  *
 759  * Every prefix refers to a set of "nexthop"s (gw, oif),
 760  * where gw must have narrower scope. This recursion stops
 761  * when gw has LOCAL scope or if "nexthop" is declared ONLINK,
 762  * which means that gw is forced to be on link.
 763  *
 764  * Code is still hairy, but now it is apparently logically
 765  * consistent and very flexible. F.e. as by-product it allows
 766  * to co-exists in peace independent exterior and interior
 767  * routing processes.
 768  *
 769  * Normally it looks as following.
 770  *
 771  * {universe prefix}  -> (gw, oif) [scope link]
 772  *                |
 773  *                |-> {link prefix} -> (gw, oif) [scope local]
 774  *                                      |
 775  *                                      |-> {local prefix} (terminal node)
 776  */
 777 static int fib_check_nh(struct fib_config *cfg, struct fib_info *fi,
 778                         struct fib_nh *nh, struct netlink_ext_ack *extack)
 779 {
 780         int err = 0;
 781         struct net *net;
 782         struct net_device *dev;
 783
 784         net = cfg->fc_nlinfo.nl_net;
 785         if (nh->nh_gw) {
 786                 struct fib_result res;
 787
 788                 if (nh->nh_flags & RTNH_F_ONLINK) {
 789                         unsigned int addr_type;
 790
 791                         if (cfg->fc_scope >= RT_SCOPE_LINK) {
 792                                 NL_SET_ERR_MSG(extack,
 793                                                "Nexthop has invalid scope");
 794                                 return -EINVAL;
 795                         }
 796                         dev = __dev_get_by_index(net, nh->nh_oif);
 797                         if (!dev)
 798                                 return -ENODEV;
 799                         if (!(dev->flags & IFF_UP)) {
 800                                 NL_SET_ERR_MSG(extack,
 801                                                "Nexthop device is not up");
 802                                 return -ENETDOWN;
 803                         }
 804                         addr_type = inet_addr_type_dev_table(net, dev, nh->nh_gw);
 805                         if (addr_type != RTN_UNICAST) {
 806                                 NL_SET_ERR_MSG(extack,
 807                                                "Nexthop has invalid gateway");
 808                                 return -EINVAL;
 809                         }
 810                         if (!netif_carrier_ok(dev))
 811                                 nh->nh_flags |= RTNH_F_LINKDOWN;
 812                         nh->nh_dev = dev;
 813                         dev_hold(dev);
 814                         nh->nh_scope = RT_SCOPE_LINK;
 815                         return 0;
 816                 }
 817                 rcu_read_lock();
 818                 {
 819                         struct fib_table *tbl = NULL;
 820                         struct flowi4 fl4 = {
 821                                 .daddr = nh->nh_gw,
 822                                 .flowi4_scope = cfg->fc_scope + 1,
 823                                 .flowi4_oif = nh->nh_oif,
 824                                 .flowi4_iif = LOOPBACK_IFINDEX,
 825                         };
 826
 827                         /* It is not necessary, but requires a bit of thinking */
 828                         if (fl4.flowi4_scope < RT_SCOPE_LINK)
 829                                 fl4.flowi4_scope = RT_SCOPE_LINK;
 830
 831                         if (cfg->fc_table)
 832                                 tbl = fib_get_table(net, cfg->fc_table);
 833
 834                         if (tbl)
 835                                 err = fib_table_lookup(tbl, &fl4, &res,
 836                                                        FIB_LOOKUP_IGNORE_LINKSTATE |
 837                                                        FIB_LOOKUP_NOREF);
 838
 839                         /* on error or if no table given do full lookup. This
 840                          * is needed for example when nexthops are in the local
 841                          * table rather than the given table
 842                          */
 843                         if (!tbl || err) {
 844                                 err = fib_lookup(net, &fl4, &res,
 845                                                  FIB_LOOKUP_IGNORE_LINKSTATE);
 846                         }
 847
 848                         if (err) {
 849                                 NL_SET_ERR_MSG(extack,
 850                                                "Nexthop has invalid gateway");
 851                                 rcu_read_unlock();
 852                                 return err;
 853                         }
 854                 }
 855                 err = -EINVAL;
 856                 if (res.type != RTN_UNICAST && res.type != RTN_LOCAL) {
 857                         NL_SET_ERR_MSG(extack, "Nexthop has invalid gateway");
 858                         goto out;
 859                 }
 860                 nh->nh_scope = res.scope;
 861                 nh->nh_oif = FIB_RES_OIF(res);
 862                 nh->nh_dev = dev = FIB_RES_DEV(res);
 863                 if (!dev) {
 864                         NL_SET_ERR_MSG(extack,
 865                                        "No egress device for nexthop gateway");
 866                         goto out;
 867                 }
 868                 dev_hold(dev);
 869                 if (!netif_carrier_ok(dev))
 870                         nh->nh_flags |= RTNH_F_LINKDOWN;
 871                 err = (dev->flags & IFF_UP) ? 0 : -ENETDOWN;
 872         } else {
 873                 struct in_device *in_dev;
 874
 875                 if (nh->nh_flags & (RTNH_F_PERVASIVE | RTNH_F_ONLINK)) {
 876                         NL_SET_ERR_MSG(extack,
 877                                        "Invalid flags for nexthop - PERVASIVE and ONLINK can not be set");
 878                         return -EINVAL;
 879                 }
 880                 rcu_read_lock();
 881                 err = -ENODEV;
 882                 in_dev = inetdev_by_index(net, nh->nh_oif);
 883                 if (!in_dev)
 884                         goto out;
 885                 err = -ENETDOWN;
 886                 if (!(in_dev->dev->flags & IFF_UP)) {
 887                         NL_SET_ERR_MSG(extack, "Device for nexthop is not up");
 888                         goto out;
 889                 }
 890                 nh->nh_dev = in_dev->dev;
 891                 dev_hold(nh->nh_dev);
 892                 nh->nh_scope = RT_SCOPE_HOST;
 893                 if (!netif_carrier_ok(nh->nh_dev))
 894                         nh->nh_flags |= RTNH_F_LINKDOWN;
 895                 err = 0;
 896         }
 897 out:
 898         rcu_read_unlock();
 899         return err;
 900 }
 901
 902 static inline unsigned int fib_laddr_hashfn(__be32 val)
 903 {
 904         unsigned int mask = (fib_info_hash_size - 1);
 905
 906         return ((__force u32)val ^
 907                 ((__force u32)val >> 7) ^
 908                 ((__force u32)val >> 14)) & mask;
 909 }
 910
 911 static struct hlist_head *fib_info_hash_alloc(int bytes)
 912 {
 913         if (bytes <= PAGE_SIZE)
 914                 return kzalloc(bytes, GFP_KERNEL);
 915         else
 916                 return (struct hlist_head *)
 917                         __get_free_pages(GFP_KERNEL | __GFP_ZERO,
 918                                          get_order(bytes));
 919 }
 920
 921 static void fib_info_hash_free(struct hlist_head *hash, int bytes)
 922 {
 923         if (!hash)
 924                 return;
 925
 926         if (bytes <= PAGE_SIZE)
 927                 kfree(hash);
 928         else
 929                 free_pages((unsigned long) hash, get_order(bytes));
 930 }
 931
 932 static void fib_info_hash_move(struct hlist_head *new_info_hash,
 933                                struct hlist_head *new_laddrhash,
 934                                unsigned int new_size)
 935 {
 936         struct hlist_head *old_info_hash, *old_laddrhash;
 937         unsigned int old_size = fib_info_hash_size;
 938         unsigned int i, bytes;
 939
 940         spin_lock_bh(&fib_info_lock);
 941         old_info_hash = fib_info_hash;
 942         old_laddrhash = fib_info_laddrhash;
 943         fib_info_hash_size = new_size;
 944
 945         for (i = 0; i < old_size; i++) {
 946                 struct hlist_head *head = &fib_info_hash[i];
 947                 struct hlist_node *n;
 948                 struct fib_info *fi;
 949
 950                 hlist_for_each_entry_safe(fi, n, head, fib_hash) {
 951                         struct hlist_head *dest;
 952                         unsigned int new_hash;
 953
 954                         new_hash = fib_info_hashfn(fi);
 955                         dest = &new_info_hash[new_hash];
 956                         hlist_add_head(&fi->fib_hash, dest);
 957                 }
 958         }
 959         fib_info_hash = new_info_hash;
 960
 961         for (i = 0; i < old_size; i++) {
 962                 struct hlist_head *lhead = &fib_info_laddrhash[i];
 963                 struct hlist_node *n;
 964                 struct fib_info *fi;
 965
 966                 hlist_for_each_entry_safe(fi, n, lhead, fib_lhash) {
 967                         struct hlist_head *ldest;
 968                         unsigned int new_hash;
 969
 970                         new_hash = fib_laddr_hashfn(fi->fib_prefsrc);
 971                         ldest = &new_laddrhash[new_hash];
 972                         hlist_add_head(&fi->fib_lhash, ldest);
 973                 }
 974         }
 975         fib_info_laddrhash = new_laddrhash;
 976
 977         spin_unlock_bh(&fib_info_lock);
 978
 979         bytes = old_size * sizeof(struct hlist_head *);
 980         fib_info_hash_free(old_info_hash, bytes);
 981         fib_info_hash_free(old_laddrhash, bytes);
 982 }
 983
 984 __be32 fib_info_update_nh_saddr(struct net *net, struct fib_nh *nh)
 985 {
 986         nh->nh_saddr = inet_select_addr(nh->nh_dev,
 987                                         nh->nh_gw,
 988                                         nh->nh_parent->fib_scope);
 989         nh->nh_saddr_genid = atomic_read(&net->ipv4.dev_addr_genid);
 990
 991         return nh->nh_saddr;
 992 }
 993
 994 static bool fib_valid_prefsrc(struct fib_config *cfg, __be32 fib_prefsrc)
 995 {
 996         if (cfg->fc_type != RTN_LOCAL || !cfg->fc_dst ||
 997             fib_prefsrc != cfg->fc_dst) {
 998                 u32 tb_id = cfg->fc_table;
 999                 int rc;
1000
1001                 if (tb_id == RT_TABLE_MAIN)
1002                         tb_id = RT_TABLE_LOCAL;
1003
1004                 rc = inet_addr_type_table(cfg->fc_nlinfo.nl_net,
1005                                           fib_prefsrc, tb_id);
1006
1007                 if (rc != RTN_LOCAL && tb_id != RT_TABLE_LOCAL) {
1008                         rc = inet_addr_type_table(cfg->fc_nlinfo.nl_net,
1009                                                   fib_prefsrc, RT_TABLE_LOCAL);
1010                 }
1011
1012                 if (rc != RTN_LOCAL)
1013                         return false;
1014         }
1015         return true;
1016 }
1017
1018 static int
1019 fib_convert_metrics(struct fib_info *fi, const struct fib_config *cfg)
1020 {
1021         bool ecn_ca = false;
1022         struct nlattr *nla;
1023         int remaining;
1024
1025         if (!cfg->fc_mx)
1026                 return 0;
1027
1028         nla_for_each_attr(nla, cfg->fc_mx, cfg->fc_mx_len, remaining) {
1029                 int type = nla_type(nla);
1030                 u32 val;
1031
1032                 if (!type)
1033                         continue;
1034                 if (type > RTAX_MAX)
1035                         return -EINVAL;
1036
1037                 if (type == RTAX_CC_ALGO) {
1038                         char tmp[TCP_CA_NAME_MAX];
1039
1040                         nla_strlcpy(tmp, nla, sizeof(tmp));
1041                         val = tcp_ca_get_key_by_name(tmp, &ecn_ca);
1042                         if (val == TCP_CA_UNSPEC)
1043                                 return -EINVAL;
1044                 } else {
1045                         val = nla_get_u32(nla);
1046                 }
1047                 if (type == RTAX_ADVMSS && val > 65535 - 40)
1048                         val = 65535 - 40;
1049                 if (type == RTAX_MTU && val > 65535 - 15)
1050                         val = 65535 - 15;
1051                 if (type == RTAX_HOPLIMIT && val > 255)
1052                         val = 255;
1053                 if (type == RTAX_FEATURES && (val & ~RTAX_FEATURE_MASK))
1054                         return -EINVAL;
1055                 fi->fib_metrics->metrics[type - 1] = val;
1056         }
1057
1058         if (ecn_ca)
1059                 fi->fib_metrics->metrics[RTAX_FEATURES - 1] |= DST_FEATURE_ECN_CA;
1060
1061         return 0;
1062 }
1063
1064 struct fib_info *fib_create_info(struct fib_config *cfg,
1065                                  struct netlink_ext_ack *extack)
1066 {
1067         int err;
1068         struct fib_info *fi = NULL;
1069         struct fib_info *ofi;
1070         int nhs = 1;
1071         struct net *net = cfg->fc_nlinfo.nl_net;
1072
1073         if (cfg->fc_type > RTN_MAX)
1074                 goto err_inval;
1075
1076         /* Fast check to catch the most weird cases */
1077         if (fib_props[cfg->fc_type].scope > cfg->fc_scope) {
1078                 NL_SET_ERR_MSG(extack, "Invalid scope");
1079                 goto err_inval;
1080         }
1081
1082         if (cfg->fc_flags & (RTNH_F_DEAD | RTNH_F_LINKDOWN)) {
1083                 NL_SET_ERR_MSG(extack,
1084                                "Invalid rtm_flags - can not contain DEAD or LINKDOWN");
1085                 goto err_inval;
1086         }
1087
1088 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1089         if (cfg->fc_mp) {
1090                 nhs = fib_count_nexthops(cfg->fc_mp, cfg->fc_mp_len, extack);
1091                 if (nhs == 0)
1092                         goto err_inval;
1093         }
1094 #endif
1095
1096         err = -ENOBUFS;
1097         if (fib_info_cnt >= fib_info_hash_size) {
1098                 unsigned int new_size = fib_info_hash_size << 1;
1099                 struct hlist_head *new_info_hash;
1100                 struct hlist_head *new_laddrhash;
1101                 unsigned int bytes;
1102
1103                 if (!new_size)
1104                         new_size = 16;
1105                 bytes = new_size * sizeof(struct hlist_head *);
1106                 new_info_hash = fib_info_hash_alloc(bytes);
1107                 new_laddrhash = fib_info_hash_alloc(bytes);
1108                 if (!new_info_hash || !new_laddrhash) {
1109                         fib_info_hash_free(new_info_hash, bytes);
1110                         fib_info_hash_free(new_laddrhash, bytes);
1111                 } else
1112                         fib_info_hash_move(new_info_hash, new_laddrhash, new_size);
1113
1114                 if (!fib_info_hash_size)
1115                         goto failure;
1116         }
1117
1118         fi = kzalloc(sizeof(*fi)+nhs*sizeof(struct fib_nh), GFP_KERNEL);
1119         if (!fi)
1120                 goto failure;
1121         if (cfg->fc_mx) {
1122                 fi->fib_metrics = kzalloc(sizeof(*fi->fib_metrics), GFP_KERNEL);
1123                 if (unlikely(!fi->fib_metrics)) {
1124                         kfree(fi);
1125                         return ERR_PTR(err);
1126                 }
1127                 refcount_set(&fi->fib_metrics->refcnt, 1);
1128         } else {
1129                 fi->fib_metrics = (struct dst_metrics *)&dst_default_metrics;
1130         }
1131         fib_info_cnt++;
1132         fi->fib_net = net;
1133         fi->fib_protocol = cfg->fc_protocol;
1134         fi->fib_scope = cfg->fc_scope;
1135         fi->fib_flags = cfg->fc_flags;
1136         fi->fib_priority = cfg->fc_priority;
1137         fi->fib_prefsrc = cfg->fc_prefsrc;
1138         fi->fib_type = cfg->fc_type;
1139         fi->fib_tb_id = cfg->fc_table;
1140
1141         fi->fib_nhs = nhs;
1142         change_nexthops(fi) {
1143                 nexthop_nh->nh_parent = fi;
1144                 nexthop_nh->nh_pcpu_rth_output = alloc_percpu(struct rtable __rcu *);
1145                 if (!nexthop_nh->nh_pcpu_rth_output)
1146                         goto failure;
1147         } endfor_nexthops(fi)
1148
1149         err = fib_convert_metrics(fi, cfg);
1150         if (err)
1151                 goto failure;
1152
1153         if (cfg->fc_mp) {
1154 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1155                 err = fib_get_nhs(fi, cfg->fc_mp, cfg->fc_mp_len, cfg, extack);
1156                 if (err != 0)
1157                         goto failure;
1158                 if (cfg->fc_oif && fi->fib_nh->nh_oif != cfg->fc_oif) {
1159                         NL_SET_ERR_MSG(extack,
1160                                        "Nexthop device index does not match RTA_OIF");
1161                         goto err_inval;
1162                 }
1163                 if (cfg->fc_gw && fi->fib_nh->nh_gw != cfg->fc_gw) {
1164                         NL_SET_ERR_MSG(extack,
1165                                        "Nexthop gateway does not match RTA_GATEWAY");
1166                         goto err_inval;
1167                 }
1168 #ifdef CONFIG_IP_ROUTE_CLASSID
1169                 if (cfg->fc_flow && fi->fib_nh->nh_tclassid != cfg->fc_flow) {
1170                         NL_SET_ERR_MSG(extack,
1171                                        "Nexthop class id does not match RTA_FLOW");
1172                         goto err_inval;
1173                 }
1174 #endif
1175 #else
1176                 NL_SET_ERR_MSG(extack,
1177                                "Multipath support not enabled in kernel");
1178                 goto err_inval;
1179 #endif
1180         } else {
1181                 struct fib_nh *nh = fi->fib_nh;
1182
1183                 if (cfg->fc_encap) {
1184                         struct lwtunnel_state *lwtstate;
1185
1186                         if (cfg->fc_encap_type == LWTUNNEL_ENCAP_NONE) {
1187                                 NL_SET_ERR_MSG(extack,
1188                                                "LWT encap type not specified");
1189                                 goto err_inval;
1190                         }
1191                         err = lwtunnel_build_state(cfg->fc_encap_type,
1192                                                    cfg->fc_encap, AF_INET, cfg,
1193                                                    &lwtstate, extack);
1194                         if (err)
1195                                 goto failure;
1196
1197                         nh->nh_lwtstate = lwtstate_get(lwtstate);
1198                 }
1199                 nh->nh_oif = cfg->fc_oif;
1200                 nh->nh_gw = cfg->fc_gw;
1201                 nh->nh_flags = cfg->fc_flags;
1202 #ifdef CONFIG_IP_ROUTE_CLASSID
1203                 nh->nh_tclassid = cfg->fc_flow;
1204                 if (nh->nh_tclassid)
1205                         fi->fib_net->ipv4.fib_num_tclassid_users++;
1206 #endif
1207 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1208                 nh->nh_weight = 1;
1209 #endif
1210         }
1211
1212         if (fib_props[cfg->fc_type].error) {
1213                 if (cfg->fc_gw || cfg->fc_oif || cfg->fc_mp) {
1214                         NL_SET_ERR_MSG(extack,
1215                                        "Gateway, device and multipath can not be specified for this route type");
1216                         goto err_inval;
1217                 }
1218                 goto link_it;
1219         } else {
1220                 switch (cfg->fc_type) {
1221                 case RTN_UNICAST:
1222                 case RTN_LOCAL:
1223                 case RTN_BROADCAST:
1224                 case RTN_ANYCAST:
1225                 case RTN_MULTICAST:
1226                         break;
1227                 default:
1228                         NL_SET_ERR_MSG(extack, "Invalid route type");
1229                         goto err_inval;
1230                 }
1231         }
1232
1233         if (cfg->fc_scope > RT_SCOPE_HOST) {
1234                 NL_SET_ERR_MSG(extack, "Invalid scope");
1235                 goto err_inval;
1236         }
1237
1238         if (cfg->fc_scope == RT_SCOPE_HOST) {
1239                 struct fib_nh *nh = fi->fib_nh;
1240
1241                 /* Local address is added. */
1242                 if (nhs != 1) {
1243                         NL_SET_ERR_MSG(extack,
1244                                        "Route with host scope can not have multiple nexthops");
1245                         goto err_inval;
1246                 }
1247                 if (nh->nh_gw) {
1248                         NL_SET_ERR_MSG(extack,
1249                                        "Route with host scope can not have a gateway");
1250                         goto err_inval;
1251                 }
1252                 nh->nh_scope = RT_SCOPE_NOWHERE;
1253                 nh->nh_dev = dev_get_by_index(net, fi->fib_nh->nh_oif);
1254                 err = -ENODEV;
1255                 if (!nh->nh_dev)
1256                         goto failure;
1257         } else {
1258                 int linkdown = 0;
1259
1260                 change_nexthops(fi) {
1261                         err = fib_check_nh(cfg, fi, nexthop_nh, extack);
1262                         if (err != 0)
1263                                 goto failure;
1264                         if (nexthop_nh->nh_flags & RTNH_F_LINKDOWN)
1265                                 linkdown++;
1266                 } endfor_nexthops(fi)
1267                 if (linkdown == fi->fib_nhs)
1268                         fi->fib_flags |= RTNH_F_LINKDOWN;
1269         }
1270
1271         if (fi->fib_prefsrc && !fib_valid_prefsrc(cfg, fi->fib_prefsrc)) {
1272                 NL_SET_ERR_MSG(extack, "Invalid prefsrc address");
1273                 goto err_inval;
1274         }
1275
1276         change_nexthops(fi) {
1277                 fib_info_update_nh_saddr(net, nexthop_nh);
1278                 fib_add_weight(fi, nexthop_nh);
1279         } endfor_nexthops(fi)
1280
1281         fib_rebalance(fi);
1282
1283 link_it:
1284         ofi = fib_find_info(fi);
1285         if (ofi) {
1286                 fi->fib_dead = 1;
1287                 free_fib_info(fi);
1288                 ofi->fib_treeref++;
1289                 return ofi;
1290         }
1291
1292         fi->fib_treeref++;
1293         refcount_set(&fi->fib_clntref, 1);
1294         spin_lock_bh(&fib_info_lock);
1295         hlist_add_head(&fi->fib_hash,
1296                        &fib_info_hash[fib_info_hashfn(fi)]);
1297         if (fi->fib_prefsrc) {
1298                 struct hlist_head *head;
1299
1300                 head = &fib_info_laddrhash[fib_laddr_hashfn(fi->fib_prefsrc)];
1301                 hlist_add_head(&fi->fib_lhash, head);
1302         }
1303         change_nexthops(fi) {
1304                 struct hlist_head *head;
1305                 unsigned int hash;
1306
1307                 if (!nexthop_nh->nh_dev)
1308                         continue;
1309                 hash = fib_devindex_hashfn(nexthop_nh->nh_dev->ifindex);
1310                 head = &fib_info_devhash[hash];
1311                 hlist_add_head(&nexthop_nh->nh_hash, head);
1312         } endfor_nexthops(fi)
1313         spin_unlock_bh(&fib_info_lock);
1314         return fi;
1315
1316 err_inval:
1317         err = -EINVAL;
1318
1319 failure:
1320         if (fi) {
1321                 fi->fib_dead = 1;
1322                 free_fib_info(fi);
1323         }
1324
1325         return ERR_PTR(err);
1326 }
1327
1328 int fib_dump_info(struct sk_buff *skb, u32 portid, u32 seq, int event,
1329                   u32 tb_id, u8 type, __be32 dst, int dst_len, u8 tos,
1330                   struct fib_info *fi, unsigned int flags)
1331 {
1332         struct nlmsghdr *nlh;
1333         struct rtmsg *rtm;
1334
1335         nlh = nlmsg_put(skb, portid, seq, event, sizeof(*rtm), flags);
1336         if (!nlh)
1337                 return -EMSGSIZE;
1338
1339         rtm = nlmsg_data(nlh);
1340         rtm->rtm_family = AF_INET;
1341         rtm->rtm_dst_len = dst_len;
1342         rtm->rtm_src_len = 0;
1343         rtm->rtm_tos = tos;
1344         if (tb_id < 256)
1345                 rtm->rtm_table = tb_id;
1346         else
1347                 rtm->rtm_table = RT_TABLE_COMPAT;
1348         if (nla_put_u32(skb, RTA_TABLE, tb_id))
1349                 goto nla_put_failure;
1350         rtm->rtm_type = type;
1351         rtm->rtm_flags = fi->fib_flags;
1352         rtm->rtm_scope = fi->fib_scope;
1353         rtm->rtm_protocol = fi->fib_protocol;
1354
1355         if (rtm->rtm_dst_len &&
1356             nla_put_in_addr(skb, RTA_DST, dst))
1357                 goto nla_put_failure;
1358         if (fi->fib_priority &&
1359             nla_put_u32(skb, RTA_PRIORITY, fi->fib_priority))
1360                 goto nla_put_failure;
1361         if (rtnetlink_put_metrics(skb, fi->fib_metrics->metrics) < 0)
1362                 goto nla_put_failure;
1363
1364         if (fi->fib_prefsrc &&
1365             nla_put_in_addr(skb, RTA_PREFSRC, fi->fib_prefsrc))
1366                 goto nla_put_failure;
1367         if (fi->fib_nhs == 1) {
1368                 struct in_device *in_dev;
1369
1370                 if (fi->fib_nh->nh_gw &&
1371                     nla_put_in_addr(skb, RTA_GATEWAY, fi->fib_nh->nh_gw))
1372                         goto nla_put_failure;
1373                 if (fi->fib_nh->nh_oif &&
1374                     nla_put_u32(skb, RTA_OIF, fi->fib_nh->nh_oif))
1375                         goto nla_put_failure;
1376                 if (fi->fib_nh->nh_flags & RTNH_F_LINKDOWN) {
1377                         in_dev = __in_dev_get_rtnl(fi->fib_nh->nh_dev);
1378                         if (in_dev &&
1379                             IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev))
1380                                 rtm->rtm_flags |= RTNH_F_DEAD;
1381                 }
1382                 if (fi->fib_nh->nh_flags & RTNH_F_OFFLOAD)
1383                         rtm->rtm_flags |= RTNH_F_OFFLOAD;
1384 #ifdef CONFIG_IP_ROUTE_CLASSID
1385                 if (fi->fib_nh[0].nh_tclassid &&
1386                     nla_put_u32(skb, RTA_FLOW, fi->fib_nh[0].nh_tclassid))
1387                         goto nla_put_failure;
1388 #endif
1389                 if (fi->fib_nh->nh_lwtstate &&
1390                     lwtunnel_fill_encap(skb, fi->fib_nh->nh_lwtstate) < 0)
1391                         goto nla_put_failure;
1392         }
1393 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1394         if (fi->fib_nhs > 1) {
1395                 struct rtnexthop *rtnh;
1396                 struct nlattr *mp;
1397
1398                 mp = nla_nest_start(skb, RTA_MULTIPATH);
1399                 if (!mp)
1400                         goto nla_put_failure;
1401
1402                 for_nexthops(fi) {
1403                         struct in_device *in_dev;
1404
1405                         rtnh = nla_reserve_nohdr(skb, sizeof(*rtnh));
1406                         if (!rtnh)
1407                                 goto nla_put_failure;
1408
1409                         rtnh->rtnh_flags = nh->nh_flags & 0xFF;
1410                         if (nh->nh_flags & RTNH_F_LINKDOWN) {
1411                                 in_dev = __in_dev_get_rtnl(nh->nh_dev);
1412                                 if (in_dev &&
1413                                     IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev))
1414                                         rtnh->rtnh_flags |= RTNH_F_DEAD;
1415                         }
1416                         rtnh->rtnh_hops = nh->nh_weight - 1;
1417                         rtnh->rtnh_ifindex = nh->nh_oif;
1418
1419                         if (nh->nh_gw &&
1420                             nla_put_in_addr(skb, RTA_GATEWAY, nh->nh_gw))
1421                                 goto nla_put_failure;
1422 #ifdef CONFIG_IP_ROUTE_CLASSID
1423                         if (nh->nh_tclassid &&
1424                             nla_put_u32(skb, RTA_FLOW, nh->nh_tclassid))
1425                                 goto nla_put_failure;
1426 #endif
1427                         if (nh->nh_lwtstate &&
1428                             lwtunnel_fill_encap(skb, nh->nh_lwtstate) < 0)
1429                                 goto nla_put_failure;
1430
1431                         /* length of rtnetlink header + attributes */
1432                         rtnh->rtnh_len = nlmsg_get_pos(skb) - (void *) rtnh;
1433                 } endfor_nexthops(fi);
1434
1435                 nla_nest_end(skb, mp);
1436         }
1437 #endif
1438         nlmsg_end(skb, nlh);
1439         return 0;
1440
1441 nla_put_failure:
1442         nlmsg_cancel(skb, nlh);
1443         return -EMSGSIZE;
1444 }
1445
1446 /*
1447  * Update FIB if:
1448  * - local address disappeared -> we must delete all the entries
1449  *   referring to it.
1450  * - device went down -> we must shutdown all nexthops going via it.
1451  */
1452 int fib_sync_down_addr(struct net_device *dev, __be32 local)
1453 {
1454         int ret = 0;
1455         unsigned int hash = fib_laddr_hashfn(local);
1456         struct hlist_head *head = &fib_info_laddrhash[hash];
1457         struct net *net = dev_net(dev);
1458         int tb_id = l3mdev_fib_table(dev);
1459         struct fib_info *fi;
1460
1461         if (!fib_info_laddrhash || local == 0)
1462                 return 0;
1463
1464         hlist_for_each_entry(fi, head, fib_lhash) {
1465                 if (!net_eq(fi->fib_net, net) ||
1466                     fi->fib_tb_id != tb_id)
1467                         continue;
1468                 if (fi->fib_prefsrc == local) {
1469                         fi->fib_flags |= RTNH_F_DEAD;
1470                         ret++;
1471                 }
1472         }
1473         return ret;
1474 }
1475
1476 static int call_fib_nh_notifiers(struct fib_nh *fib_nh,
1477                                  enum fib_event_type event_type)
1478 {
1479         struct in_device *in_dev = __in_dev_get_rtnl(fib_nh->nh_dev);
1480         struct fib_nh_notifier_info info = {
1481                 .fib_nh = fib_nh,
1482         };
1483
1484         switch (event_type) {
1485         case FIB_EVENT_NH_ADD:
1486                 if (fib_nh->nh_flags & RTNH_F_DEAD)
1487                         break;
1488                 if (IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev) &&
1489                     fib_nh->nh_flags & RTNH_F_LINKDOWN)
1490                         break;
1491                 return call_fib4_notifiers(dev_net(fib_nh->nh_dev), event_type,
1492                                            &info.info);
1493         case FIB_EVENT_NH_DEL:
1494                 if ((in_dev && IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev) &&
1495                      fib_nh->nh_flags & RTNH_F_LINKDOWN) ||
1496                     (fib_nh->nh_flags & RTNH_F_DEAD))
1497                         return call_fib4_notifiers(dev_net(fib_nh->nh_dev),
1498                                                    event_type, &info.info);
1499         default:
1500                 break;
1501         }
1502
1503         return NOTIFY_DONE;
1504 }
1505
1506 /* Event              force Flags           Description
1507  * NETDEV_CHANGE      0     LINKDOWN        Carrier OFF, not for scope host
1508  * NETDEV_DOWN        0     LINKDOWN|DEAD   Link down, not for scope host
1509  * NETDEV_DOWN        1     LINKDOWN|DEAD   Last address removed
1510  * NETDEV_UNREGISTER  1     LINKDOWN|DEAD   Device removed
1511  */
1512 int fib_sync_down_dev(struct net_device *dev, unsigned long event, bool force)
1513 {
1514         int ret = 0;
1515         int scope = RT_SCOPE_NOWHERE;
1516         struct fib_info *prev_fi = NULL;
1517         unsigned int hash = fib_devindex_hashfn(dev->ifindex);
1518         struct hlist_head *head = &fib_info_devhash[hash];
1519         struct fib_nh *nh;
1520
1521         if (force)
1522                 scope = -1;
1523
1524         hlist_for_each_entry(nh, head, nh_hash) {
1525                 struct fib_info *fi = nh->nh_parent;
1526                 int dead;
1527
1528                 BUG_ON(!fi->fib_nhs);
1529                 if (nh->nh_dev != dev || fi == prev_fi)
1530                         continue;
1531                 prev_fi = fi;
1532                 dead = 0;
1533                 change_nexthops(fi) {
1534                         if (nexthop_nh->nh_flags & RTNH_F_DEAD)
1535                                 dead++;
1536                         else if (nexthop_nh->nh_dev == dev &&
1537                                  nexthop_nh->nh_scope != scope) {
1538                                 switch (event) {
1539                                 case NETDEV_DOWN:
1540                                 case NETDEV_UNREGISTER:
1541                                         nexthop_nh->nh_flags |= RTNH_F_DEAD;
1542                                         /* fall through */
1543                                 case NETDEV_CHANGE:
1544                                         nexthop_nh->nh_flags |= RTNH_F_LINKDOWN;
1545                                         break;
1546                                 }
1547                                 call_fib_nh_notifiers(nexthop_nh,
1548                                                       FIB_EVENT_NH_DEL);
1549                                 dead++;
1550                         }
1551 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1552                         if (event == NETDEV_UNREGISTER &&
1553                             nexthop_nh->nh_dev == dev) {
1554                                 dead = fi->fib_nhs;
1555                                 break;
1556                         }
1557 #endif
1558                 } endfor_nexthops(fi)
1559                 if (dead == fi->fib_nhs) {
1560                         switch (event) {
1561                         case NETDEV_DOWN:
1562                         case NETDEV_UNREGISTER:
1563                                 fi->fib_flags |= RTNH_F_DEAD;
1564                                 /* fall through */
1565                         case NETDEV_CHANGE:
1566                                 fi->fib_flags |= RTNH_F_LINKDOWN;
1567                                 break;
1568                         }
1569                         ret++;
1570                 }
1571
1572                 fib_rebalance(fi);
1573         }
1574
1575         return ret;
1576 }
1577
1578 /* Must be invoked inside of an RCU protected region.  */
1579 static void fib_select_default(const struct flowi4 *flp, struct fib_result *res)
1580 {
1581         struct fib_info *fi = NULL, *last_resort = NULL;
1582         struct hlist_head *fa_head = res->fa_head;
1583         struct fib_table *tb = res->table;
1584         u8 slen = 32 - res->prefixlen;
1585         int order = -1, last_idx = -1;
1586         struct fib_alias *fa, *fa1 = NULL;
1587         u32 last_prio = res->fi->fib_priority;
1588         u8 last_tos = 0;
1589
1590         hlist_for_each_entry_rcu(fa, fa_head, fa_list) {
1591                 struct fib_info *next_fi = fa->fa_info;
1592
1593                 if (fa->fa_slen != slen)
1594                         continue;
1595                 if (fa->fa_tos && fa->fa_tos != flp->flowi4_tos)
1596                         continue;
1597                 if (fa->tb_id != tb->tb_id)
1598                         continue;
1599                 if (next_fi->fib_priority > last_prio &&
1600                     fa->fa_tos == last_tos) {
1601                         if (last_tos)
1602                                 continue;
1603                         break;
1604                 }
1605                 if (next_fi->fib_flags & RTNH_F_DEAD)
1606                         continue;
1607                 last_tos = fa->fa_tos;
1608                 last_prio = next_fi->fib_priority;
1609
1610                 if (next_fi->fib_scope != res->scope ||
1611                     fa->fa_type != RTN_UNICAST)
1612                         continue;
1613                 if (!next_fi->fib_nh[0].nh_gw ||
1614                     next_fi->fib_nh[0].nh_scope != RT_SCOPE_LINK)
1615                         continue;
1616
1617                 fib_alias_accessed(fa);
1618
1619                 if (!fi) {
1620                         if (next_fi != res->fi)
1621                                 break;
1622                         fa1 = fa;
1623                 } else if (!fib_detect_death(fi, order, &last_resort,
1624                                              &last_idx, fa1->fa_default)) {
1625                         fib_result_assign(res, fi);
1626                         fa1->fa_default = order;
1627                         goto out;
1628                 }
1629                 fi = next_fi;
1630                 order++;
1631         }
1632
1633         if (order <= 0 || !fi) {
1634                 if (fa1)
1635                         fa1->fa_default = -1;
1636                 goto out;
1637         }
1638
1639         if (!fib_detect_death(fi, order, &last_resort, &last_idx,
1640                               fa1->fa_default)) {
1641                 fib_result_assign(res, fi);
1642                 fa1->fa_default = order;
1643                 goto out;
1644         }
1645
1646         if (last_idx >= 0)
1647                 fib_result_assign(res, last_resort);
1648         fa1->fa_default = last_idx;
1649 out:
1650         return;
1651 }
1652
1653 /*
1654  * Dead device goes up. We wake up dead nexthops.
1655  * It takes sense only on multipath routes.
1656  */
1657 int fib_sync_up(struct net_device *dev, unsigned int nh_flags)
1658 {
1659         struct fib_info *prev_fi;
1660         unsigned int hash;
1661         struct hlist_head *head;
1662         struct fib_nh *nh;
1663         int ret;
1664
1665         if (!(dev->flags & IFF_UP))
1666                 return 0;
1667
1668         if (nh_flags & RTNH_F_DEAD) {
1669                 unsigned int flags = dev_get_flags(dev);
1670
1671                 if (flags & (IFF_RUNNING | IFF_LOWER_UP))
1672                         nh_flags |= RTNH_F_LINKDOWN;
1673         }
1674
1675         prev_fi = NULL;
1676         hash = fib_devindex_hashfn(dev->ifindex);
1677         head = &fib_info_devhash[hash];
1678         ret = 0;
1679
1680         hlist_for_each_entry(nh, head, nh_hash) {
1681                 struct fib_info *fi = nh->nh_parent;
1682                 int alive;
1683
1684                 BUG_ON(!fi->fib_nhs);
1685                 if (nh->nh_dev != dev || fi == prev_fi)
1686                         continue;
1687
1688                 prev_fi = fi;
1689                 alive = 0;
1690                 change_nexthops(fi) {
1691                         if (!(nexthop_nh->nh_flags & nh_flags)) {
1692                                 alive++;
1693                                 continue;
1694                         }
1695                         if (!nexthop_nh->nh_dev ||
1696                             !(nexthop_nh->nh_dev->flags & IFF_UP))
1697                                 continue;
1698                         if (nexthop_nh->nh_dev != dev ||
1699                             !__in_dev_get_rtnl(dev))
1700                                 continue;
1701                         alive++;
1702                         nexthop_nh->nh_flags &= ~nh_flags;
1703                         call_fib_nh_notifiers(nexthop_nh, FIB_EVENT_NH_ADD);
1704                 } endfor_nexthops(fi)
1705
1706                 if (alive > 0) {
1707                         fi->fib_flags &= ~nh_flags;
1708                         ret++;
1709                 }
1710
1711                 fib_rebalance(fi);
1712         }
1713
1714         return ret;
1715 }
1716
1717 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1718 static bool fib_good_nh(const struct fib_nh *nh)
1719 {
1720         int state = NUD_REACHABLE;
1721
1722         if (nh->nh_scope == RT_SCOPE_LINK) {
1723                 struct neighbour *n;
1724
1725                 rcu_read_lock_bh();
1726
1727                 n = __ipv4_neigh_lookup_noref(nh->nh_dev,
1728                                               (__force u32)nh->nh_gw);
1729                 if (n)
1730                         state = n->nud_state;
1731
1732                 rcu_read_unlock_bh();
1733         }
1734
1735         return !!(state & NUD_VALID);
1736 }
1737
1738 void fib_select_multipath(struct fib_result *res, int hash)
1739 {
1740         struct fib_info *fi = res->fi;
1741         struct net *net = fi->fib_net;
1742         bool first = false;
1743
1744         for_nexthops(fi) {
1745                 if (hash > atomic_read(&nh->nh_upper_bound))
1746                         continue;
1747
1748                 if (!net->ipv4.sysctl_fib_multipath_use_neigh ||
1749                     fib_good_nh(nh)) {
1750                         res->nh_sel = nhsel;
1751                         return;
1752                 }
1753                 if (!first) {
1754                         res->nh_sel = nhsel;
1755                         first = true;
1756                 }
1757         } endfor_nexthops(fi);
1758 }
1759 #endif
1760
1761 void fib_select_path(struct net *net, struct fib_result *res,
1762                      struct flowi4 *fl4, const struct sk_buff *skb)
1763 {
1764         bool oif_check;
1765
1766         oif_check = (fl4->flowi4_oif == 0 ||
1767                      fl4->flowi4_flags & FLOWI_FLAG_SKIP_NH_OIF);
1768
1769 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1770         if (res->fi->fib_nhs > 1 && oif_check) {
1771                 int h = fib_multipath_hash(res->fi, fl4, skb);
1772
1773                 fib_select_multipath(res, h);
1774         }
1775         else
1776 #endif
1777         if (!res->prefixlen &&
1778             res->table->tb_num_default > 1 &&
1779             res->type == RTN_UNICAST && oif_check)
1780                 fib_select_default(fl4, res);
1781
1782         if (!fl4->saddr)
1783                 fl4->saddr = FIB_RES_PREFSRC(net, *res);
1784 }
1785 EXPORT_SYMBOL_GPL(fib_select_path);