net/ipv4/fib_semantics.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * INET         An implementation of the TCP/IP protocol suite for the LINUX
   4  *              operating system.  INET is implemented using the  BSD Socket
   5  *              interface as the means of communication with the user level.
   6  *
   7  *              IPv4 Forwarding Information Base: semantics.
   8  *
   9  * Authors:     Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
  10  */
  11
  12 #include <linux/uaccess.h>
  13 #include <linux/bitops.h>
  14 #include <linux/types.h>
  15 #include <linux/kernel.h>
  16 #include <linux/jiffies.h>
  17 #include <linux/mm.h>
  18 #include <linux/string.h>
  19 #include <linux/socket.h>
  20 #include <linux/sockios.h>
  21 #include <linux/errno.h>
  22 #include <linux/in.h>
  23 #include <linux/inet.h>
  24 #include <linux/inetdevice.h>
  25 #include <linux/netdevice.h>
  26 #include <linux/if_arp.h>
  27 #include <linux/proc_fs.h>
  28 #include <linux/skbuff.h>
  29 #include <linux/init.h>
  30 #include <linux/slab.h>
  31 #include <linux/netlink.h>
  32 #include <linux/hash.h>
  33 #include <linux/nospec.h>
  34
  35 #include <net/arp.h>
  36 #include <net/inet_dscp.h>
  37 #include <net/ip.h>
  38 #include <net/protocol.h>
  39 #include <net/route.h>
  40 #include <net/tcp.h>
  41 #include <net/sock.h>
  42 #include <net/ip_fib.h>
  43 #include <net/ip6_fib.h>
  44 #include <net/nexthop.h>
  45 #include <net/netlink.h>
  46 #include <net/rtnh.h>
  47 #include <net/lwtunnel.h>
  48 #include <net/fib_notifier.h>
  49 #include <net/addrconf.h>
  50
  51 #include "fib_lookup.h"
  52
  53 static DEFINE_SPINLOCK(fib_info_lock);
  54 static struct hlist_head *fib_info_hash;
  55 static struct hlist_head *fib_info_laddrhash;
  56 static unsigned int fib_info_hash_size;
  57 static unsigned int fib_info_hash_bits;
  58 static unsigned int fib_info_cnt;
  59
  60 #define DEVINDEX_HASHBITS 8
  61 #define DEVINDEX_HASHSIZE (1U << DEVINDEX_HASHBITS)
  62 static struct hlist_head fib_info_devhash[DEVINDEX_HASHSIZE];
  63
  64 /* for_nexthops and change_nexthops only used when nexthop object
  65  * is not set in a fib_info. The logic within can reference fib_nh.
  66  */
  67 #ifdef CONFIG_IP_ROUTE_MULTIPATH
  68
  69 #define for_nexthops(fi) {                                              \
  70         int nhsel; const struct fib_nh *nh;                             \
  71         for (nhsel = 0, nh = (fi)->fib_nh;                              \
  72              nhsel < fib_info_num_path((fi));                           \
  73              nh++, nhsel++)
  74
  75 #define change_nexthops(fi) {                                           \
  76         int nhsel; struct fib_nh *nexthop_nh;                           \
  77         for (nhsel = 0, nexthop_nh = (struct fib_nh *)((fi)->fib_nh);   \
  78              nhsel < fib_info_num_path((fi));                           \
  79              nexthop_nh++, nhsel++)
  80
  81 #else /* CONFIG_IP_ROUTE_MULTIPATH */
  82
  83 /* Hope, that gcc will optimize it to get rid of dummy loop */
  84
  85 #define for_nexthops(fi) {                                              \
  86         int nhsel; const struct fib_nh *nh = (fi)->fib_nh;              \
  87         for (nhsel = 0; nhsel < 1; nhsel++)
  88
  89 #define change_nexthops(fi) {                                           \
  90         int nhsel;                                                      \
  91         struct fib_nh *nexthop_nh = (struct fib_nh *)((fi)->fib_nh);    \
  92         for (nhsel = 0; nhsel < 1; nhsel++)
  93
  94 #endif /* CONFIG_IP_ROUTE_MULTIPATH */
  95
  96 #define endfor_nexthops(fi) }
  97
  98
  99 const struct fib_prop fib_props[RTN_MAX + 1] = {
 100         [RTN_UNSPEC] = {
 101                 .error  = 0,
 102                 .scope  = RT_SCOPE_NOWHERE,
 103         },
 104         [RTN_UNICAST] = {
 105                 .error  = 0,
 106                 .scope  = RT_SCOPE_UNIVERSE,
 107         },
 108         [RTN_LOCAL] = {
 109                 .error  = 0,
 110                 .scope  = RT_SCOPE_HOST,
 111         },
 112         [RTN_BROADCAST] = {
 113                 .error  = 0,
 114                 .scope  = RT_SCOPE_LINK,
 115         },
 116         [RTN_ANYCAST] = {
 117                 .error  = 0,
 118                 .scope  = RT_SCOPE_LINK,
 119         },
 120         [RTN_MULTICAST] = {
 121                 .error  = 0,
 122                 .scope  = RT_SCOPE_UNIVERSE,
 123         },
 124         [RTN_BLACKHOLE] = {
 125                 .error  = -EINVAL,
 126                 .scope  = RT_SCOPE_UNIVERSE,
 127         },
 128         [RTN_UNREACHABLE] = {
 129                 .error  = -EHOSTUNREACH,
 130                 .scope  = RT_SCOPE_UNIVERSE,
 131         },
 132         [RTN_PROHIBIT] = {
 133                 .error  = -EACCES,
 134                 .scope  = RT_SCOPE_UNIVERSE,
 135         },
 136         [RTN_THROW] = {
 137                 .error  = -EAGAIN,
 138                 .scope  = RT_SCOPE_UNIVERSE,
 139         },
 140         [RTN_NAT] = {
 141                 .error  = -EINVAL,
 142                 .scope  = RT_SCOPE_NOWHERE,
 143         },
 144         [RTN_XRESOLVE] = {
 145                 .error  = -EINVAL,
 146                 .scope  = RT_SCOPE_NOWHERE,
 147         },
 148 };
 149
 150 static void rt_fibinfo_free(struct rtable __rcu **rtp)
 151 {
 152         struct rtable *rt = rcu_dereference_protected(*rtp, 1);
 153
 154         if (!rt)
 155                 return;
 156
 157         /* Not even needed : RCU_INIT_POINTER(*rtp, NULL);
 158          * because we waited an RCU grace period before calling
 159          * free_fib_info_rcu()
 160          */
 161
 162         dst_dev_put(&rt->dst);
 163         dst_release_immediate(&rt->dst);
 164 }
 165
 166 static void free_nh_exceptions(struct fib_nh_common *nhc)
 167 {
 168         struct fnhe_hash_bucket *hash;
 169         int i;
 170
 171         hash = rcu_dereference_protected(nhc->nhc_exceptions, 1);
 172         if (!hash)
 173                 return;
 174         for (i = 0; i < FNHE_HASH_SIZE; i++) {
 175                 struct fib_nh_exception *fnhe;
 176
 177                 fnhe = rcu_dereference_protected(hash[i].chain, 1);
 178                 while (fnhe) {
 179                         struct fib_nh_exception *next;
 180
 181                         next = rcu_dereference_protected(fnhe->fnhe_next, 1);
 182
 183                         rt_fibinfo_free(&fnhe->fnhe_rth_input);
 184                         rt_fibinfo_free(&fnhe->fnhe_rth_output);
 185
 186                         kfree(fnhe);
 187
 188                         fnhe = next;
 189                 }
 190         }
 191         kfree(hash);
 192 }
 193
 194 static void rt_fibinfo_free_cpus(struct rtable __rcu * __percpu *rtp)
 195 {
 196         int cpu;
 197
 198         if (!rtp)
 199                 return;
 200
 201         for_each_possible_cpu(cpu) {
 202                 struct rtable *rt;
 203
 204                 rt = rcu_dereference_protected(*per_cpu_ptr(rtp, cpu), 1);
 205                 if (rt) {
 206                         dst_dev_put(&rt->dst);
 207                         dst_release_immediate(&rt->dst);
 208                 }
 209         }
 210         free_percpu(rtp);
 211 }
 212
 213 void fib_nh_common_release(struct fib_nh_common *nhc)
 214 {
 215         netdev_put(nhc->nhc_dev, &nhc->nhc_dev_tracker);
 216         lwtstate_put(nhc->nhc_lwtstate);
 217         rt_fibinfo_free_cpus(nhc->nhc_pcpu_rth_output);
 218         rt_fibinfo_free(&nhc->nhc_rth_input);
 219         free_nh_exceptions(nhc);
 220 }
 221 EXPORT_SYMBOL_GPL(fib_nh_common_release);
 222
 223 void fib_nh_release(struct net *net, struct fib_nh *fib_nh)
 224 {
 225 #ifdef CONFIG_IP_ROUTE_CLASSID
 226         if (fib_nh->nh_tclassid)
 227                 atomic_dec(&net->ipv4.fib_num_tclassid_users);
 228 #endif
 229         fib_nh_common_release(&fib_nh->nh_common);
 230 }
 231
 232 /* Release a nexthop info record */
 233 static void free_fib_info_rcu(struct rcu_head *head)
 234 {
 235         struct fib_info *fi = container_of(head, struct fib_info, rcu);
 236
 237         if (fi->nh) {
 238                 nexthop_put(fi->nh);
 239         } else {
 240                 change_nexthops(fi) {
 241                         fib_nh_release(fi->fib_net, nexthop_nh);
 242                 } endfor_nexthops(fi);
 243         }
 244
 245         ip_fib_metrics_put(fi->fib_metrics);
 246
 247         kfree(fi);
 248 }
 249
 250 void free_fib_info(struct fib_info *fi)
 251 {
 252         if (fi->fib_dead == 0) {
 253                 pr_warn("Freeing alive fib_info %p\n", fi);
 254                 return;
 255         }
 256
 257         call_rcu(&fi->rcu, free_fib_info_rcu);
 258 }
 259 EXPORT_SYMBOL_GPL(free_fib_info);
 260
 261 void fib_release_info(struct fib_info *fi)
 262 {
 263         spin_lock_bh(&fib_info_lock);
 264         if (fi && refcount_dec_and_test(&fi->fib_treeref)) {
 265                 hlist_del(&fi->fib_hash);
 266
 267                 /* Paired with READ_ONCE() in fib_create_info(). */
 268                 WRITE_ONCE(fib_info_cnt, fib_info_cnt - 1);
 269
 270                 if (fi->fib_prefsrc)
 271                         hlist_del(&fi->fib_lhash);
 272                 if (fi->nh) {
 273                         list_del(&fi->nh_list);
 274                 } else {
 275                         change_nexthops(fi) {
 276                                 if (!nexthop_nh->fib_nh_dev)
 277                                         continue;
 278                                 hlist_del(&nexthop_nh->nh_hash);
 279                         } endfor_nexthops(fi)
 280                 }
 281                 /* Paired with READ_ONCE() from fib_table_lookup() */
 282                 WRITE_ONCE(fi->fib_dead, 1);
 283                 fib_info_put(fi);
 284         }
 285         spin_unlock_bh(&fib_info_lock);
 286 }
 287
 288 static inline int nh_comp(struct fib_info *fi, struct fib_info *ofi)
 289 {
 290         const struct fib_nh *onh;
 291
 292         if (fi->nh || ofi->nh)
 293                 return nexthop_cmp(fi->nh, ofi->nh) ? 0 : -1;
 294
 295         if (ofi->fib_nhs == 0)
 296                 return 0;
 297
 298         for_nexthops(fi) {
 299                 onh = fib_info_nh(ofi, nhsel);
 300
 301                 if (nh->fib_nh_oif != onh->fib_nh_oif ||
 302                     nh->fib_nh_gw_family != onh->fib_nh_gw_family ||
 303                     nh->fib_nh_scope != onh->fib_nh_scope ||
 304 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 305                     nh->fib_nh_weight != onh->fib_nh_weight ||
 306 #endif
 307 #ifdef CONFIG_IP_ROUTE_CLASSID
 308                     nh->nh_tclassid != onh->nh_tclassid ||
 309 #endif
 310                     lwtunnel_cmp_encap(nh->fib_nh_lws, onh->fib_nh_lws) ||
 311                     ((nh->fib_nh_flags ^ onh->fib_nh_flags) & ~RTNH_COMPARE_MASK))
 312                         return -1;
 313
 314                 if (nh->fib_nh_gw_family == AF_INET &&
 315                     nh->fib_nh_gw4 != onh->fib_nh_gw4)
 316                         return -1;
 317
 318                 if (nh->fib_nh_gw_family == AF_INET6 &&
 319                     ipv6_addr_cmp(&nh->fib_nh_gw6, &onh->fib_nh_gw6))
 320                         return -1;
 321         } endfor_nexthops(fi);
 322         return 0;
 323 }
 324
 325 static inline unsigned int fib_devindex_hashfn(unsigned int val)
 326 {
 327         return hash_32(val, DEVINDEX_HASHBITS);
 328 }
 329
 330 static struct hlist_head *
 331 fib_info_devhash_bucket(const struct net_device *dev)
 332 {
 333         u32 val = net_hash_mix(dev_net(dev)) ^ dev->ifindex;
 334
 335         return &fib_info_devhash[fib_devindex_hashfn(val)];
 336 }
 337
 338 static unsigned int fib_info_hashfn_1(int init_val, u8 protocol, u8 scope,
 339                                       u32 prefsrc, u32 priority)
 340 {
 341         unsigned int val = init_val;
 342
 343         val ^= (protocol << 8) | scope;
 344         val ^= prefsrc;
 345         val ^= priority;
 346
 347         return val;
 348 }
 349
 350 static unsigned int fib_info_hashfn_result(unsigned int val)
 351 {
 352         unsigned int mask = (fib_info_hash_size - 1);
 353
 354         return (val ^ (val >> 7) ^ (val >> 12)) & mask;
 355 }
 356
 357 static inline unsigned int fib_info_hashfn(struct fib_info *fi)
 358 {
 359         unsigned int val;
 360
 361         val = fib_info_hashfn_1(fi->fib_nhs, fi->fib_protocol,
 362                                 fi->fib_scope, (__force u32)fi->fib_prefsrc,
 363                                 fi->fib_priority);
 364
 365         if (fi->nh) {
 366                 val ^= fib_devindex_hashfn(fi->nh->id);
 367         } else {
 368                 for_nexthops(fi) {
 369                         val ^= fib_devindex_hashfn(nh->fib_nh_oif);
 370                 } endfor_nexthops(fi)
 371         }
 372
 373         return fib_info_hashfn_result(val);
 374 }
 375
 376 /* no metrics, only nexthop id */
 377 static struct fib_info *fib_find_info_nh(struct net *net,
 378                                          const struct fib_config *cfg)
 379 {
 380         struct hlist_head *head;
 381         struct fib_info *fi;
 382         unsigned int hash;
 383
 384         hash = fib_info_hashfn_1(fib_devindex_hashfn(cfg->fc_nh_id),
 385                                  cfg->fc_protocol, cfg->fc_scope,
 386                                  (__force u32)cfg->fc_prefsrc,
 387                                  cfg->fc_priority);
 388         hash = fib_info_hashfn_result(hash);
 389         head = &fib_info_hash[hash];
 390
 391         hlist_for_each_entry(fi, head, fib_hash) {
 392                 if (!net_eq(fi->fib_net, net))
 393                         continue;
 394                 if (!fi->nh || fi->nh->id != cfg->fc_nh_id)
 395                         continue;
 396                 if (cfg->fc_protocol == fi->fib_protocol &&
 397                     cfg->fc_scope == fi->fib_scope &&
 398                     cfg->fc_prefsrc == fi->fib_prefsrc &&
 399                     cfg->fc_priority == fi->fib_priority &&
 400                     cfg->fc_type == fi->fib_type &&
 401                     cfg->fc_table == fi->fib_tb_id &&
 402                     !((cfg->fc_flags ^ fi->fib_flags) & ~RTNH_COMPARE_MASK))
 403                         return fi;
 404         }
 405
 406         return NULL;
 407 }
 408
 409 static struct fib_info *fib_find_info(struct fib_info *nfi)
 410 {
 411         struct hlist_head *head;
 412         struct fib_info *fi;
 413         unsigned int hash;
 414
 415         hash = fib_info_hashfn(nfi);
 416         head = &fib_info_hash[hash];
 417
 418         hlist_for_each_entry(fi, head, fib_hash) {
 419                 if (!net_eq(fi->fib_net, nfi->fib_net))
 420                         continue;
 421                 if (fi->fib_nhs != nfi->fib_nhs)
 422                         continue;
 423                 if (nfi->fib_protocol == fi->fib_protocol &&
 424                     nfi->fib_scope == fi->fib_scope &&
 425                     nfi->fib_prefsrc == fi->fib_prefsrc &&
 426                     nfi->fib_priority == fi->fib_priority &&
 427                     nfi->fib_type == fi->fib_type &&
 428                     nfi->fib_tb_id == fi->fib_tb_id &&
 429                     memcmp(nfi->fib_metrics, fi->fib_metrics,
 430                            sizeof(u32) * RTAX_MAX) == 0 &&
 431                     !((nfi->fib_flags ^ fi->fib_flags) & ~RTNH_COMPARE_MASK) &&
 432                     nh_comp(fi, nfi) == 0)
 433                         return fi;
 434         }
 435
 436         return NULL;
 437 }
 438
 439 /* Check, that the gateway is already configured.
 440  * Used only by redirect accept routine.
 441  */
 442 int ip_fib_check_default(__be32 gw, struct net_device *dev)
 443 {
 444         struct hlist_head *head;
 445         struct fib_nh *nh;
 446
 447         spin_lock(&fib_info_lock);
 448
 449         head = fib_info_devhash_bucket(dev);
 450
 451         hlist_for_each_entry(nh, head, nh_hash) {
 452                 if (nh->fib_nh_dev == dev &&
 453                     nh->fib_nh_gw4 == gw &&
 454                     !(nh->fib_nh_flags & RTNH_F_DEAD)) {
 455                         spin_unlock(&fib_info_lock);
 456                         return 0;
 457                 }
 458         }
 459
 460         spin_unlock(&fib_info_lock);
 461
 462         return -1;
 463 }
 464
 465 size_t fib_nlmsg_size(struct fib_info *fi)
 466 {
 467         size_t payload = NLMSG_ALIGN(sizeof(struct rtmsg))
 468                          + nla_total_size(4) /* RTA_TABLE */
 469                          + nla_total_size(4) /* RTA_DST */
 470                          + nla_total_size(4) /* RTA_PRIORITY */
 471                          + nla_total_size(4) /* RTA_PREFSRC */
 472                          + nla_total_size(TCP_CA_NAME_MAX); /* RTAX_CC_ALGO */
 473         unsigned int nhs = fib_info_num_path(fi);
 474
 475         /* space for nested metrics */
 476         payload += nla_total_size((RTAX_MAX * nla_total_size(4)));
 477
 478         if (fi->nh)
 479                 payload += nla_total_size(4); /* RTA_NH_ID */
 480
 481         if (nhs) {
 482                 size_t nh_encapsize = 0;
 483                 /* Also handles the special case nhs == 1 */
 484
 485                 /* each nexthop is packed in an attribute */
 486                 size_t nhsize = nla_total_size(sizeof(struct rtnexthop));
 487                 unsigned int i;
 488
 489                 /* may contain flow and gateway attribute */
 490                 nhsize += 2 * nla_total_size(4);
 491
 492                 /* grab encap info */
 493                 for (i = 0; i < fib_info_num_path(fi); i++) {
 494                         struct fib_nh_common *nhc = fib_info_nhc(fi, i);
 495
 496                         if (nhc->nhc_lwtstate) {
 497                                 /* RTA_ENCAP_TYPE */
 498                                 nh_encapsize += lwtunnel_get_encap_size(
 499                                                 nhc->nhc_lwtstate);
 500                                 /* RTA_ENCAP */
 501                                 nh_encapsize +=  nla_total_size(2);
 502                         }
 503                 }
 504
 505                 /* all nexthops are packed in a nested attribute */
 506                 payload += nla_total_size((nhs * nhsize) + nh_encapsize);
 507
 508         }
 509
 510         return payload;
 511 }
 512
 513 void rtmsg_fib(int event, __be32 key, struct fib_alias *fa,
 514                int dst_len, u32 tb_id, const struct nl_info *info,
 515                unsigned int nlm_flags)
 516 {
 517         struct fib_rt_info fri;
 518         struct sk_buff *skb;
 519         u32 seq = info->nlh ? info->nlh->nlmsg_seq : 0;
 520         int err = -ENOBUFS;
 521
 522         skb = nlmsg_new(fib_nlmsg_size(fa->fa_info), GFP_KERNEL);
 523         if (!skb)
 524                 goto errout;
 525
 526         fri.fi = fa->fa_info;
 527         fri.tb_id = tb_id;
 528         fri.dst = key;
 529         fri.dst_len = dst_len;
 530         fri.dscp = fa->fa_dscp;
 531         fri.type = fa->fa_type;
 532         fri.offload = READ_ONCE(fa->offload);
 533         fri.trap = READ_ONCE(fa->trap);
 534         fri.offload_failed = READ_ONCE(fa->offload_failed);
 535         err = fib_dump_info(skb, info->portid, seq, event, &fri, nlm_flags);
 536         if (err < 0) {
 537                 /* -EMSGSIZE implies BUG in fib_nlmsg_size() */
 538                 WARN_ON(err == -EMSGSIZE);
 539                 kfree_skb(skb);
 540                 goto errout;
 541         }
 542         rtnl_notify(skb, info->nl_net, info->portid, RTNLGRP_IPV4_ROUTE,
 543                     info->nlh, GFP_KERNEL);
 544         return;
 545 errout:
 546         if (err < 0)
 547                 rtnl_set_sk_err(info->nl_net, RTNLGRP_IPV4_ROUTE, err);
 548 }
 549
 550 static int fib_detect_death(struct fib_info *fi, int order,
 551                             struct fib_info **last_resort, int *last_idx,
 552                             int dflt)
 553 {
 554         const struct fib_nh_common *nhc = fib_info_nhc(fi, 0);
 555         struct neighbour *n;
 556         int state = NUD_NONE;
 557
 558         if (likely(nhc->nhc_gw_family == AF_INET))
 559                 n = neigh_lookup(&arp_tbl, &nhc->nhc_gw.ipv4, nhc->nhc_dev);
 560         else if (nhc->nhc_gw_family == AF_INET6)
 561                 n = neigh_lookup(ipv6_stub->nd_tbl, &nhc->nhc_gw.ipv6,
 562                                  nhc->nhc_dev);
 563         else
 564                 n = NULL;
 565
 566         if (n) {
 567                 state = READ_ONCE(n->nud_state);
 568                 neigh_release(n);
 569         } else {
 570                 return 0;
 571         }
 572         if (state == NUD_REACHABLE)
 573                 return 0;
 574         if ((state & NUD_VALID) && order != dflt)
 575                 return 0;
 576         if ((state & NUD_VALID) ||
 577             (*last_idx < 0 && order > dflt && state != NUD_INCOMPLETE)) {
 578                 *last_resort = fi;
 579                 *last_idx = order;
 580         }
 581         return 1;
 582 }
 583
 584 int fib_nh_common_init(struct net *net, struct fib_nh_common *nhc,
 585                        struct nlattr *encap, u16 encap_type,
 586                        void *cfg, gfp_t gfp_flags,
 587                        struct netlink_ext_ack *extack)
 588 {
 589         int err;
 590
 591         nhc->nhc_pcpu_rth_output = alloc_percpu_gfp(struct rtable __rcu *,
 592                                                     gfp_flags);
 593         if (!nhc->nhc_pcpu_rth_output)
 594                 return -ENOMEM;
 595
 596         if (encap) {
 597                 struct lwtunnel_state *lwtstate;
 598
 599                 if (encap_type == LWTUNNEL_ENCAP_NONE) {
 600                         NL_SET_ERR_MSG(extack, "LWT encap type not specified");
 601                         err = -EINVAL;
 602                         goto lwt_failure;
 603                 }
 604                 err = lwtunnel_build_state(net, encap_type, encap,
 605                                            nhc->nhc_family, cfg, &lwtstate,
 606                                            extack);
 607                 if (err)
 608                         goto lwt_failure;
 609
 610                 nhc->nhc_lwtstate = lwtstate_get(lwtstate);
 611         }
 612
 613         return 0;
 614
 615 lwt_failure:
 616         rt_fibinfo_free_cpus(nhc->nhc_pcpu_rth_output);
 617         nhc->nhc_pcpu_rth_output = NULL;
 618         return err;
 619 }
 620 EXPORT_SYMBOL_GPL(fib_nh_common_init);
 621
 622 int fib_nh_init(struct net *net, struct fib_nh *nh,
 623                 struct fib_config *cfg, int nh_weight,
 624                 struct netlink_ext_ack *extack)
 625 {
 626         int err;
 627
 628         nh->fib_nh_family = AF_INET;
 629
 630         err = fib_nh_common_init(net, &nh->nh_common, cfg->fc_encap,
 631                                  cfg->fc_encap_type, cfg, GFP_KERNEL, extack);
 632         if (err)
 633                 return err;
 634
 635         nh->fib_nh_oif = cfg->fc_oif;
 636         nh->fib_nh_gw_family = cfg->fc_gw_family;
 637         if (cfg->fc_gw_family == AF_INET)
 638                 nh->fib_nh_gw4 = cfg->fc_gw4;
 639         else if (cfg->fc_gw_family == AF_INET6)
 640                 nh->fib_nh_gw6 = cfg->fc_gw6;
 641
 642         nh->fib_nh_flags = cfg->fc_flags;
 643
 644 #ifdef CONFIG_IP_ROUTE_CLASSID
 645         nh->nh_tclassid = cfg->fc_flow;
 646         if (nh->nh_tclassid)
 647                 atomic_inc(&net->ipv4.fib_num_tclassid_users);
 648 #endif
 649 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 650         nh->fib_nh_weight = nh_weight;
 651 #endif
 652         return 0;
 653 }
 654
 655 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 656
 657 static int fib_count_nexthops(struct rtnexthop *rtnh, int remaining,
 658                               struct netlink_ext_ack *extack)
 659 {
 660         int nhs = 0;
 661
 662         while (rtnh_ok(rtnh, remaining)) {
 663                 nhs++;
 664                 rtnh = rtnh_next(rtnh, &remaining);
 665         }
 666
 667         /* leftover implies invalid nexthop configuration, discard it */
 668         if (remaining > 0) {
 669                 NL_SET_ERR_MSG(extack,
 670                                "Invalid nexthop configuration - extra data after nexthops");
 671                 nhs = 0;
 672         }
 673
 674         return nhs;
 675 }
 676
 677 static int fib_gw_from_attr(__be32 *gw, struct nlattr *nla,
 678                             struct netlink_ext_ack *extack)
 679 {
 680         if (nla_len(nla) < sizeof(*gw)) {
 681                 NL_SET_ERR_MSG(extack, "Invalid IPv4 address in RTA_GATEWAY");
 682                 return -EINVAL;
 683         }
 684
 685         *gw = nla_get_in_addr(nla);
 686
 687         return 0;
 688 }
 689
 690 /* only called when fib_nh is integrated into fib_info */
 691 static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh,
 692                        int remaining, struct fib_config *cfg,
 693                        struct netlink_ext_ack *extack)
 694 {
 695         struct net *net = fi->fib_net;
 696         struct fib_config fib_cfg;
 697         struct fib_nh *nh;
 698         int ret;
 699
 700         change_nexthops(fi) {
 701                 int attrlen;
 702
 703                 memset(&fib_cfg, 0, sizeof(fib_cfg));
 704
 705                 if (!rtnh_ok(rtnh, remaining)) {
 706                         NL_SET_ERR_MSG(extack,
 707                                        "Invalid nexthop configuration - extra data after nexthop");
 708                         return -EINVAL;
 709                 }
 710
 711                 if (rtnh->rtnh_flags & (RTNH_F_DEAD | RTNH_F_LINKDOWN)) {
 712                         NL_SET_ERR_MSG(extack,
 713                                        "Invalid flags for nexthop - can not contain DEAD or LINKDOWN");
 714                         return -EINVAL;
 715                 }
 716
 717                 fib_cfg.fc_flags = (cfg->fc_flags & ~0xFF) | rtnh->rtnh_flags;
 718                 fib_cfg.fc_oif = rtnh->rtnh_ifindex;
 719
 720                 attrlen = rtnh_attrlen(rtnh);
 721                 if (attrlen > 0) {
 722                         struct nlattr *nla, *nlav, *attrs = rtnh_attrs(rtnh);
 723
 724                         nla = nla_find(attrs, attrlen, RTA_GATEWAY);
 725                         nlav = nla_find(attrs, attrlen, RTA_VIA);
 726                         if (nla && nlav) {
 727                                 NL_SET_ERR_MSG(extack,
 728                                                "Nexthop configuration can not contain both GATEWAY and VIA");
 729                                 return -EINVAL;
 730                         }
 731                         if (nla) {
 732                                 ret = fib_gw_from_attr(&fib_cfg.fc_gw4, nla,
 733                                                        extack);
 734                                 if (ret)
 735                                         goto errout;
 736
 737                                 if (fib_cfg.fc_gw4)
 738                                         fib_cfg.fc_gw_family = AF_INET;
 739                         } else if (nlav) {
 740                                 ret = fib_gw_from_via(&fib_cfg, nlav, extack);
 741                                 if (ret)
 742                                         goto errout;
 743                         }
 744
 745                         nla = nla_find(attrs, attrlen, RTA_FLOW);
 746                         if (nla) {
 747                                 if (nla_len(nla) < sizeof(u32)) {
 748                                         NL_SET_ERR_MSG(extack, "Invalid RTA_FLOW");
 749                                         return -EINVAL;
 750                                 }
 751                                 fib_cfg.fc_flow = nla_get_u32(nla);
 752                         }
 753
 754                         fib_cfg.fc_encap = nla_find(attrs, attrlen, RTA_ENCAP);
 755                         /* RTA_ENCAP_TYPE length checked in
 756                          * lwtunnel_valid_encap_type_attr
 757                          */
 758                         nla = nla_find(attrs, attrlen, RTA_ENCAP_TYPE);
 759                         if (nla)
 760                                 fib_cfg.fc_encap_type = nla_get_u16(nla);
 761                 }
 762
 763                 ret = fib_nh_init(net, nexthop_nh, &fib_cfg,
 764                                   rtnh->rtnh_hops + 1, extack);
 765                 if (ret)
 766                         goto errout;
 767
 768                 rtnh = rtnh_next(rtnh, &remaining);
 769         } endfor_nexthops(fi);
 770
 771         ret = -EINVAL;
 772         nh = fib_info_nh(fi, 0);
 773         if (cfg->fc_oif && nh->fib_nh_oif != cfg->fc_oif) {
 774                 NL_SET_ERR_MSG(extack,
 775                                "Nexthop device index does not match RTA_OIF");
 776                 goto errout;
 777         }
 778         if (cfg->fc_gw_family) {
 779                 if (cfg->fc_gw_family != nh->fib_nh_gw_family ||
 780                     (cfg->fc_gw_family == AF_INET &&
 781                      nh->fib_nh_gw4 != cfg->fc_gw4) ||
 782                     (cfg->fc_gw_family == AF_INET6 &&
 783                      ipv6_addr_cmp(&nh->fib_nh_gw6, &cfg->fc_gw6))) {
 784                         NL_SET_ERR_MSG(extack,
 785                                        "Nexthop gateway does not match RTA_GATEWAY or RTA_VIA");
 786                         goto errout;
 787                 }
 788         }
 789 #ifdef CONFIG_IP_ROUTE_CLASSID
 790         if (cfg->fc_flow && nh->nh_tclassid != cfg->fc_flow) {
 791                 NL_SET_ERR_MSG(extack,
 792                                "Nexthop class id does not match RTA_FLOW");
 793                 goto errout;
 794         }
 795 #endif
 796         ret = 0;
 797 errout:
 798         return ret;
 799 }
 800
 801 /* only called when fib_nh is integrated into fib_info */
 802 static void fib_rebalance(struct fib_info *fi)
 803 {
 804         int total;
 805         int w;
 806
 807         if (fib_info_num_path(fi) < 2)
 808                 return;
 809
 810         total = 0;
 811         for_nexthops(fi) {
 812                 if (nh->fib_nh_flags & RTNH_F_DEAD)
 813                         continue;
 814
 815                 if (ip_ignore_linkdown(nh->fib_nh_dev) &&
 816                     nh->fib_nh_flags & RTNH_F_LINKDOWN)
 817                         continue;
 818
 819                 total += nh->fib_nh_weight;
 820         } endfor_nexthops(fi);
 821
 822         w = 0;
 823         change_nexthops(fi) {
 824                 int upper_bound;
 825
 826                 if (nexthop_nh->fib_nh_flags & RTNH_F_DEAD) {
 827                         upper_bound = -1;
 828                 } else if (ip_ignore_linkdown(nexthop_nh->fib_nh_dev) &&
 829                            nexthop_nh->fib_nh_flags & RTNH_F_LINKDOWN) {
 830                         upper_bound = -1;
 831                 } else {
 832                         w += nexthop_nh->fib_nh_weight;
 833                         upper_bound = DIV_ROUND_CLOSEST_ULL((u64)w << 31,
 834                                                             total) - 1;
 835                 }
 836
 837                 atomic_set(&nexthop_nh->fib_nh_upper_bound, upper_bound);
 838         } endfor_nexthops(fi);
 839 }
 840 #else /* CONFIG_IP_ROUTE_MULTIPATH */
 841
 842 static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh,
 843                        int remaining, struct fib_config *cfg,
 844                        struct netlink_ext_ack *extack)
 845 {
 846         NL_SET_ERR_MSG(extack, "Multipath support not enabled in kernel");
 847
 848         return -EINVAL;
 849 }
 850
 851 #define fib_rebalance(fi) do { } while (0)
 852
 853 #endif /* CONFIG_IP_ROUTE_MULTIPATH */
 854
 855 static int fib_encap_match(struct net *net, u16 encap_type,
 856                            struct nlattr *encap,
 857                            const struct fib_nh *nh,
 858                            const struct fib_config *cfg,
 859                            struct netlink_ext_ack *extack)
 860 {
 861         struct lwtunnel_state *lwtstate;
 862         int ret, result = 0;
 863
 864         if (encap_type == LWTUNNEL_ENCAP_NONE)
 865                 return 0;
 866
 867         ret = lwtunnel_build_state(net, encap_type, encap, AF_INET,
 868                                    cfg, &lwtstate, extack);
 869         if (!ret) {
 870                 result = lwtunnel_cmp_encap(lwtstate, nh->fib_nh_lws);
 871                 lwtstate_free(lwtstate);
 872         }
 873
 874         return result;
 875 }
 876
 877 int fib_nh_match(struct net *net, struct fib_config *cfg, struct fib_info *fi,
 878                  struct netlink_ext_ack *extack)
 879 {
 880 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 881         struct rtnexthop *rtnh;
 882         int remaining;
 883 #endif
 884
 885         if (cfg->fc_priority && cfg->fc_priority != fi->fib_priority)
 886                 return 1;
 887
 888         if (cfg->fc_nh_id) {
 889                 if (fi->nh && cfg->fc_nh_id == fi->nh->id)
 890                         return 0;
 891                 return 1;
 892         }
 893
 894         if (fi->nh) {
 895                 if (cfg->fc_oif || cfg->fc_gw_family || cfg->fc_mp)
 896                         return 1;
 897                 return 0;
 898         }
 899
 900         if (cfg->fc_oif || cfg->fc_gw_family) {
 901                 struct fib_nh *nh;
 902
 903                 nh = fib_info_nh(fi, 0);
 904                 if (cfg->fc_encap) {
 905                         if (fib_encap_match(net, cfg->fc_encap_type,
 906                                             cfg->fc_encap, nh, cfg, extack))
 907                                 return 1;
 908                 }
 909 #ifdef CONFIG_IP_ROUTE_CLASSID
 910                 if (cfg->fc_flow &&
 911                     cfg->fc_flow != nh->nh_tclassid)
 912                         return 1;
 913 #endif
 914                 if ((cfg->fc_oif && cfg->fc_oif != nh->fib_nh_oif) ||
 915                     (cfg->fc_gw_family &&
 916                      cfg->fc_gw_family != nh->fib_nh_gw_family))
 917                         return 1;
 918
 919                 if (cfg->fc_gw_family == AF_INET &&
 920                     cfg->fc_gw4 != nh->fib_nh_gw4)
 921                         return 1;
 922
 923                 if (cfg->fc_gw_family == AF_INET6 &&
 924                     ipv6_addr_cmp(&cfg->fc_gw6, &nh->fib_nh_gw6))
 925                         return 1;
 926
 927                 return 0;
 928         }
 929
 930 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 931         if (!cfg->fc_mp)
 932                 return 0;
 933
 934         rtnh = cfg->fc_mp;
 935         remaining = cfg->fc_mp_len;
 936
 937         for_nexthops(fi) {
 938                 int attrlen;
 939
 940                 if (!rtnh_ok(rtnh, remaining))
 941                         return -EINVAL;
 942
 943                 if (rtnh->rtnh_ifindex && rtnh->rtnh_ifindex != nh->fib_nh_oif)
 944                         return 1;
 945
 946                 attrlen = rtnh_attrlen(rtnh);
 947                 if (attrlen > 0) {
 948                         struct nlattr *nla, *nlav, *attrs = rtnh_attrs(rtnh);
 949                         int err;
 950
 951                         nla = nla_find(attrs, attrlen, RTA_GATEWAY);
 952                         nlav = nla_find(attrs, attrlen, RTA_VIA);
 953                         if (nla && nlav) {
 954                                 NL_SET_ERR_MSG(extack,
 955                                                "Nexthop configuration can not contain both GATEWAY and VIA");
 956                                 return -EINVAL;
 957                         }
 958
 959                         if (nla) {
 960                                 __be32 gw;
 961
 962                                 err = fib_gw_from_attr(&gw, nla, extack);
 963                                 if (err)
 964                                         return err;
 965
 966                                 if (nh->fib_nh_gw_family != AF_INET ||
 967                                     gw != nh->fib_nh_gw4)
 968                                         return 1;
 969                         } else if (nlav) {
 970                                 struct fib_config cfg2;
 971
 972                                 err = fib_gw_from_via(&cfg2, nlav, extack);
 973                                 if (err)
 974                                         return err;
 975
 976                                 switch (nh->fib_nh_gw_family) {
 977                                 case AF_INET:
 978                                         if (cfg2.fc_gw_family != AF_INET ||
 979                                             cfg2.fc_gw4 != nh->fib_nh_gw4)
 980                                                 return 1;
 981                                         break;
 982                                 case AF_INET6:
 983                                         if (cfg2.fc_gw_family != AF_INET6 ||
 984                                             ipv6_addr_cmp(&cfg2.fc_gw6,
 985                                                           &nh->fib_nh_gw6))
 986                                                 return 1;
 987                                         break;
 988                                 }
 989                         }
 990
 991 #ifdef CONFIG_IP_ROUTE_CLASSID
 992                         nla = nla_find(attrs, attrlen, RTA_FLOW);
 993                         if (nla) {
 994                                 if (nla_len(nla) < sizeof(u32)) {
 995                                         NL_SET_ERR_MSG(extack, "Invalid RTA_FLOW");
 996                                         return -EINVAL;
 997                                 }
 998                                 if (nla_get_u32(nla) != nh->nh_tclassid)
 999                                         return 1;
1000                         }
1001 #endif
1002                 }
1003
1004                 rtnh = rtnh_next(rtnh, &remaining);
1005         } endfor_nexthops(fi);
1006 #endif
1007         return 0;
1008 }
1009
1010 bool fib_metrics_match(struct fib_config *cfg, struct fib_info *fi)
1011 {
1012         struct nlattr *nla;
1013         int remaining;
1014
1015         if (!cfg->fc_mx)
1016                 return true;
1017
1018         nla_for_each_attr(nla, cfg->fc_mx, cfg->fc_mx_len, remaining) {
1019                 int type = nla_type(nla);
1020                 u32 fi_val, val;
1021
1022                 if (!type)
1023                         continue;
1024                 if (type > RTAX_MAX)
1025                         return false;
1026
1027                 type = array_index_nospec(type, RTAX_MAX + 1);
1028                 if (type == RTAX_CC_ALGO) {
1029                         char tmp[TCP_CA_NAME_MAX];
1030                         bool ecn_ca = false;
1031
1032                         nla_strscpy(tmp, nla, sizeof(tmp));
1033                         val = tcp_ca_get_key_by_name(fi->fib_net, tmp, &ecn_ca);
1034                 } else {
1035                         if (nla_len(nla) != sizeof(u32))
1036                                 return false;
1037                         val = nla_get_u32(nla);
1038                 }
1039
1040                 fi_val = fi->fib_metrics->metrics[type - 1];
1041                 if (type == RTAX_FEATURES)
1042                         fi_val &= ~DST_FEATURE_ECN_CA;
1043
1044                 if (fi_val != val)
1045                         return false;
1046         }
1047
1048         return true;
1049 }
1050
1051 static int fib_check_nh_v6_gw(struct net *net, struct fib_nh *nh,
1052                               u32 table, struct netlink_ext_ack *extack)
1053 {
1054         struct fib6_config cfg = {
1055                 .fc_table = table,
1056                 .fc_flags = nh->fib_nh_flags | RTF_GATEWAY,
1057                 .fc_ifindex = nh->fib_nh_oif,
1058                 .fc_gateway = nh->fib_nh_gw6,
1059         };
1060         struct fib6_nh fib6_nh = {};
1061         int err;
1062
1063         err = ipv6_stub->fib6_nh_init(net, &fib6_nh, &cfg, GFP_KERNEL, extack);
1064         if (!err) {
1065                 nh->fib_nh_dev = fib6_nh.fib_nh_dev;
1066                 netdev_hold(nh->fib_nh_dev, &nh->fib_nh_dev_tracker,
1067                             GFP_KERNEL);
1068                 nh->fib_nh_oif = nh->fib_nh_dev->ifindex;
1069                 nh->fib_nh_scope = RT_SCOPE_LINK;
1070
1071                 ipv6_stub->fib6_nh_release(&fib6_nh);
1072         }
1073
1074         return err;
1075 }
1076
1077 /*
1078  * Picture
1079  * -------
1080  *
1081  * Semantics of nexthop is very messy by historical reasons.
1082  * We have to take into account, that:
1083  * a) gateway can be actually local interface address,
1084  *    so that gatewayed route is direct.
1085  * b) gateway must be on-link address, possibly
1086  *    described not by an ifaddr, but also by a direct route.
1087  * c) If both gateway and interface are specified, they should not
1088  *    contradict.
1089  * d) If we use tunnel routes, gateway could be not on-link.
1090  *
1091  * Attempt to reconcile all of these (alas, self-contradictory) conditions
1092  * results in pretty ugly and hairy code with obscure logic.
1093  *
1094  * I chose to generalized it instead, so that the size
1095  * of code does not increase practically, but it becomes
1096  * much more general.
1097  * Every prefix is assigned a "scope" value: "host" is local address,
1098  * "link" is direct route,
1099  * [ ... "site" ... "interior" ... ]
1100  * and "universe" is true gateway route with global meaning.
1101  *
1102  * Every prefix refers to a set of "nexthop"s (gw, oif),
1103  * where gw must have narrower scope. This recursion stops
1104  * when gw has LOCAL scope or if "nexthop" is declared ONLINK,
1105  * which means that gw is forced to be on link.
1106  *
1107  * Code is still hairy, but now it is apparently logically
1108  * consistent and very flexible. F.e. as by-product it allows
1109  * to co-exists in peace independent exterior and interior
1110  * routing processes.
1111  *
1112  * Normally it looks as following.
1113  *
1114  * {universe prefix}  -> (gw, oif) [scope link]
1115  *                |
1116  *                |-> {link prefix} -> (gw, oif) [scope local]
1117  *                                      |
1118  *                                      |-> {local prefix} (terminal node)
1119  */
1120 static int fib_check_nh_v4_gw(struct net *net, struct fib_nh *nh, u32 table,
1121                               u8 scope, struct netlink_ext_ack *extack)
1122 {
1123         struct net_device *dev;
1124         struct fib_result res;
1125         int err = 0;
1126
1127         if (nh->fib_nh_flags & RTNH_F_ONLINK) {
1128                 unsigned int addr_type;
1129
1130                 if (scope >= RT_SCOPE_LINK) {
1131                         NL_SET_ERR_MSG(extack, "Nexthop has invalid scope");
1132                         return -EINVAL;
1133                 }
1134                 dev = __dev_get_by_index(net, nh->fib_nh_oif);
1135                 if (!dev) {
1136                         NL_SET_ERR_MSG(extack, "Nexthop device required for onlink");
1137                         return -ENODEV;
1138                 }
1139                 if (!(dev->flags & IFF_UP)) {
1140                         NL_SET_ERR_MSG(extack, "Nexthop device is not up");
1141                         return -ENETDOWN;
1142                 }
1143                 addr_type = inet_addr_type_dev_table(net, dev, nh->fib_nh_gw4);
1144                 if (addr_type != RTN_UNICAST) {
1145                         NL_SET_ERR_MSG(extack, "Nexthop has invalid gateway");
1146                         return -EINVAL;
1147                 }
1148                 if (!netif_carrier_ok(dev))
1149                         nh->fib_nh_flags |= RTNH_F_LINKDOWN;
1150                 nh->fib_nh_dev = dev;
1151                 netdev_hold(dev, &nh->fib_nh_dev_tracker, GFP_ATOMIC);
1152                 nh->fib_nh_scope = RT_SCOPE_LINK;
1153                 return 0;
1154         }
1155         rcu_read_lock();
1156         {
1157                 struct fib_table *tbl = NULL;
1158                 struct flowi4 fl4 = {
1159                         .daddr = nh->fib_nh_gw4,
1160                         .flowi4_scope = scope + 1,
1161                         .flowi4_oif = nh->fib_nh_oif,
1162                         .flowi4_iif = LOOPBACK_IFINDEX,
1163                 };
1164
1165                 /* It is not necessary, but requires a bit of thinking */
1166                 if (fl4.flowi4_scope < RT_SCOPE_LINK)
1167                         fl4.flowi4_scope = RT_SCOPE_LINK;
1168
1169                 if (table && table != RT_TABLE_MAIN)
1170                         tbl = fib_get_table(net, table);
1171
1172                 if (tbl)
1173                         err = fib_table_lookup(tbl, &fl4, &res,
1174                                                FIB_LOOKUP_IGNORE_LINKSTATE |
1175                                                FIB_LOOKUP_NOREF);
1176
1177                 /* on error or if no table given do full lookup. This
1178                  * is needed for example when nexthops are in the local
1179                  * table rather than the given table
1180                  */
1181                 if (!tbl || err) {
1182                         err = fib_lookup(net, &fl4, &res,
1183                                          FIB_LOOKUP_IGNORE_LINKSTATE);
1184                 }
1185
1186                 if (err) {
1187                         NL_SET_ERR_MSG(extack, "Nexthop has invalid gateway");
1188                         goto out;
1189                 }
1190         }
1191
1192         err = -EINVAL;
1193         if (res.type != RTN_UNICAST && res.type != RTN_LOCAL) {
1194                 NL_SET_ERR_MSG(extack, "Nexthop has invalid gateway");
1195                 goto out;
1196         }
1197         nh->fib_nh_scope = res.scope;
1198         nh->fib_nh_oif = FIB_RES_OIF(res);
1199         nh->fib_nh_dev = dev = FIB_RES_DEV(res);
1200         if (!dev) {
1201                 NL_SET_ERR_MSG(extack,
1202                                "No egress device for nexthop gateway");
1203                 goto out;
1204         }
1205         netdev_hold(dev, &nh->fib_nh_dev_tracker, GFP_ATOMIC);
1206         if (!netif_carrier_ok(dev))
1207                 nh->fib_nh_flags |= RTNH_F_LINKDOWN;
1208         err = (dev->flags & IFF_UP) ? 0 : -ENETDOWN;
1209 out:
1210         rcu_read_unlock();
1211         return err;
1212 }
1213
1214 static int fib_check_nh_nongw(struct net *net, struct fib_nh *nh,
1215                               struct netlink_ext_ack *extack)
1216 {
1217         struct in_device *in_dev;
1218         int err;
1219
1220         if (nh->fib_nh_flags & (RTNH_F_PERVASIVE | RTNH_F_ONLINK)) {
1221                 NL_SET_ERR_MSG(extack,
1222                                "Invalid flags for nexthop - PERVASIVE and ONLINK can not be set");
1223                 return -EINVAL;
1224         }
1225
1226         rcu_read_lock();
1227
1228         err = -ENODEV;
1229         in_dev = inetdev_by_index(net, nh->fib_nh_oif);
1230         if (!in_dev)
1231                 goto out;
1232         err = -ENETDOWN;
1233         if (!(in_dev->dev->flags & IFF_UP)) {
1234                 NL_SET_ERR_MSG(extack, "Device for nexthop is not up");
1235                 goto out;
1236         }
1237
1238         nh->fib_nh_dev = in_dev->dev;
1239         netdev_hold(nh->fib_nh_dev, &nh->fib_nh_dev_tracker, GFP_ATOMIC);
1240         nh->fib_nh_scope = RT_SCOPE_HOST;
1241         if (!netif_carrier_ok(nh->fib_nh_dev))
1242                 nh->fib_nh_flags |= RTNH_F_LINKDOWN;
1243         err = 0;
1244 out:
1245         rcu_read_unlock();
1246         return err;
1247 }
1248
1249 int fib_check_nh(struct net *net, struct fib_nh *nh, u32 table, u8 scope,
1250                  struct netlink_ext_ack *extack)
1251 {
1252         int err;
1253
1254         if (nh->fib_nh_gw_family == AF_INET)
1255                 err = fib_check_nh_v4_gw(net, nh, table, scope, extack);
1256         else if (nh->fib_nh_gw_family == AF_INET6)
1257                 err = fib_check_nh_v6_gw(net, nh, table, extack);
1258         else
1259                 err = fib_check_nh_nongw(net, nh, extack);
1260
1261         return err;
1262 }
1263
1264 static struct hlist_head *
1265 fib_info_laddrhash_bucket(const struct net *net, __be32 val)
1266 {
1267         u32 slot = hash_32(net_hash_mix(net) ^ (__force u32)val,
1268                            fib_info_hash_bits);
1269
1270         return &fib_info_laddrhash[slot];
1271 }
1272
1273 static void fib_info_hash_move(struct hlist_head *new_info_hash,
1274                                struct hlist_head *new_laddrhash,
1275                                unsigned int new_size)
1276 {
1277         struct hlist_head *old_info_hash, *old_laddrhash;
1278         unsigned int old_size = fib_info_hash_size;
1279         unsigned int i;
1280
1281         spin_lock_bh(&fib_info_lock);
1282         old_info_hash = fib_info_hash;
1283         old_laddrhash = fib_info_laddrhash;
1284         fib_info_hash_size = new_size;
1285         fib_info_hash_bits = ilog2(new_size);
1286
1287         for (i = 0; i < old_size; i++) {
1288                 struct hlist_head *head = &fib_info_hash[i];
1289                 struct hlist_node *n;
1290                 struct fib_info *fi;
1291
1292                 hlist_for_each_entry_safe(fi, n, head, fib_hash) {
1293                         struct hlist_head *dest;
1294                         unsigned int new_hash;
1295
1296                         new_hash = fib_info_hashfn(fi);
1297                         dest = &new_info_hash[new_hash];
1298                         hlist_add_head(&fi->fib_hash, dest);
1299                 }
1300         }
1301         fib_info_hash = new_info_hash;
1302
1303         fib_info_laddrhash = new_laddrhash;
1304         for (i = 0; i < old_size; i++) {
1305                 struct hlist_head *lhead = &old_laddrhash[i];
1306                 struct hlist_node *n;
1307                 struct fib_info *fi;
1308
1309                 hlist_for_each_entry_safe(fi, n, lhead, fib_lhash) {
1310                         struct hlist_head *ldest;
1311
1312                         ldest = fib_info_laddrhash_bucket(fi->fib_net,
1313                                                           fi->fib_prefsrc);
1314                         hlist_add_head(&fi->fib_lhash, ldest);
1315                 }
1316         }
1317
1318         spin_unlock_bh(&fib_info_lock);
1319
1320         kvfree(old_info_hash);
1321         kvfree(old_laddrhash);
1322 }
1323
1324 __be32 fib_info_update_nhc_saddr(struct net *net, struct fib_nh_common *nhc,
1325                                  unsigned char scope)
1326 {
1327         struct fib_nh *nh;
1328
1329         if (nhc->nhc_family != AF_INET)
1330                 return inet_select_addr(nhc->nhc_dev, 0, scope);
1331
1332         nh = container_of(nhc, struct fib_nh, nh_common);
1333         nh->nh_saddr = inet_select_addr(nh->fib_nh_dev, nh->fib_nh_gw4, scope);
1334         nh->nh_saddr_genid = atomic_read(&net->ipv4.dev_addr_genid);
1335
1336         return nh->nh_saddr;
1337 }
1338
1339 __be32 fib_result_prefsrc(struct net *net, struct fib_result *res)
1340 {
1341         struct fib_nh_common *nhc = res->nhc;
1342
1343         if (res->fi->fib_prefsrc)
1344                 return res->fi->fib_prefsrc;
1345
1346         if (nhc->nhc_family == AF_INET) {
1347                 struct fib_nh *nh;
1348
1349                 nh = container_of(nhc, struct fib_nh, nh_common);
1350                 if (nh->nh_saddr_genid == atomic_read(&net->ipv4.dev_addr_genid))
1351                         return nh->nh_saddr;
1352         }
1353
1354         return fib_info_update_nhc_saddr(net, nhc, res->fi->fib_scope);
1355 }
1356
1357 static bool fib_valid_prefsrc(struct fib_config *cfg, __be32 fib_prefsrc)
1358 {
1359         if (cfg->fc_type != RTN_LOCAL || !cfg->fc_dst ||
1360             fib_prefsrc != cfg->fc_dst) {
1361                 u32 tb_id = cfg->fc_table;
1362                 int rc;
1363
1364                 if (tb_id == RT_TABLE_MAIN)
1365                         tb_id = RT_TABLE_LOCAL;
1366
1367                 rc = inet_addr_type_table(cfg->fc_nlinfo.nl_net,
1368                                           fib_prefsrc, tb_id);
1369
1370                 if (rc != RTN_LOCAL && tb_id != RT_TABLE_LOCAL) {
1371                         rc = inet_addr_type_table(cfg->fc_nlinfo.nl_net,
1372                                                   fib_prefsrc, RT_TABLE_LOCAL);
1373                 }
1374
1375                 if (rc != RTN_LOCAL)
1376                         return false;
1377         }
1378         return true;
1379 }
1380
1381 struct fib_info *fib_create_info(struct fib_config *cfg,
1382                                  struct netlink_ext_ack *extack)
1383 {
1384         int err;
1385         struct fib_info *fi = NULL;
1386         struct nexthop *nh = NULL;
1387         struct fib_info *ofi;
1388         int nhs = 1;
1389         struct net *net = cfg->fc_nlinfo.nl_net;
1390
1391         if (cfg->fc_type > RTN_MAX)
1392                 goto err_inval;
1393
1394         /* Fast check to catch the most weird cases */
1395         if (fib_props[cfg->fc_type].scope > cfg->fc_scope) {
1396                 NL_SET_ERR_MSG(extack, "Invalid scope");
1397                 goto err_inval;
1398         }
1399
1400         if (cfg->fc_flags & (RTNH_F_DEAD | RTNH_F_LINKDOWN)) {
1401                 NL_SET_ERR_MSG(extack,
1402                                "Invalid rtm_flags - can not contain DEAD or LINKDOWN");
1403                 goto err_inval;
1404         }
1405
1406         if (cfg->fc_nh_id) {
1407                 if (!cfg->fc_mx) {
1408                         fi = fib_find_info_nh(net, cfg);
1409                         if (fi) {
1410                                 refcount_inc(&fi->fib_treeref);
1411                                 return fi;
1412                         }
1413                 }
1414
1415                 nh = nexthop_find_by_id(net, cfg->fc_nh_id);
1416                 if (!nh) {
1417                         NL_SET_ERR_MSG(extack, "Nexthop id does not exist");
1418                         goto err_inval;
1419                 }
1420                 nhs = 0;
1421         }
1422
1423 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1424         if (cfg->fc_mp) {
1425                 nhs = fib_count_nexthops(cfg->fc_mp, cfg->fc_mp_len, extack);
1426                 if (nhs == 0)
1427                         goto err_inval;
1428         }
1429 #endif
1430
1431         err = -ENOBUFS;
1432
1433         /* Paired with WRITE_ONCE() in fib_release_info() */
1434         if (READ_ONCE(fib_info_cnt) >= fib_info_hash_size) {
1435                 unsigned int new_size = fib_info_hash_size << 1;
1436                 struct hlist_head *new_info_hash;
1437                 struct hlist_head *new_laddrhash;
1438                 size_t bytes;
1439
1440                 if (!new_size)
1441                         new_size = 16;
1442                 bytes = (size_t)new_size * sizeof(struct hlist_head *);
1443                 new_info_hash = kvzalloc(bytes, GFP_KERNEL);
1444                 new_laddrhash = kvzalloc(bytes, GFP_KERNEL);
1445                 if (!new_info_hash || !new_laddrhash) {
1446                         kvfree(new_info_hash);
1447                         kvfree(new_laddrhash);
1448                 } else {
1449                         fib_info_hash_move(new_info_hash, new_laddrhash, new_size);
1450                 }
1451                 if (!fib_info_hash_size)
1452                         goto failure;
1453         }
1454
1455         fi = kzalloc(struct_size(fi, fib_nh, nhs), GFP_KERNEL);
1456         if (!fi)
1457                 goto failure;
1458         fi->fib_metrics = ip_fib_metrics_init(fi->fib_net, cfg->fc_mx,
1459                                               cfg->fc_mx_len, extack);
1460         if (IS_ERR(fi->fib_metrics)) {
1461                 err = PTR_ERR(fi->fib_metrics);
1462                 kfree(fi);
1463                 return ERR_PTR(err);
1464         }
1465
1466         fi->fib_net = net;
1467         fi->fib_protocol = cfg->fc_protocol;
1468         fi->fib_scope = cfg->fc_scope;
1469         fi->fib_flags = cfg->fc_flags;
1470         fi->fib_priority = cfg->fc_priority;
1471         fi->fib_prefsrc = cfg->fc_prefsrc;
1472         fi->fib_type = cfg->fc_type;
1473         fi->fib_tb_id = cfg->fc_table;
1474
1475         fi->fib_nhs = nhs;
1476         if (nh) {
1477                 if (!nexthop_get(nh)) {
1478                         NL_SET_ERR_MSG(extack, "Nexthop has been deleted");
1479                         err = -EINVAL;
1480                 } else {
1481                         err = 0;
1482                         fi->nh = nh;
1483                 }
1484         } else {
1485                 change_nexthops(fi) {
1486                         nexthop_nh->nh_parent = fi;
1487                 } endfor_nexthops(fi)
1488
1489                 if (cfg->fc_mp)
1490                         err = fib_get_nhs(fi, cfg->fc_mp, cfg->fc_mp_len, cfg,
1491                                           extack);
1492                 else
1493                         err = fib_nh_init(net, fi->fib_nh, cfg, 1, extack);
1494         }
1495
1496         if (err != 0)
1497                 goto failure;
1498
1499         if (fib_props[cfg->fc_type].error) {
1500                 if (cfg->fc_gw_family || cfg->fc_oif || cfg->fc_mp) {
1501                         NL_SET_ERR_MSG(extack,
1502                                        "Gateway, device and multipath can not be specified for this route type");
1503                         goto err_inval;
1504                 }
1505                 goto link_it;
1506         } else {
1507                 switch (cfg->fc_type) {
1508                 case RTN_UNICAST:
1509                 case RTN_LOCAL:
1510                 case RTN_BROADCAST:
1511                 case RTN_ANYCAST:
1512                 case RTN_MULTICAST:
1513                         break;
1514                 default:
1515                         NL_SET_ERR_MSG(extack, "Invalid route type");
1516                         goto err_inval;
1517                 }
1518         }
1519
1520         if (cfg->fc_scope > RT_SCOPE_HOST) {
1521                 NL_SET_ERR_MSG(extack, "Invalid scope");
1522                 goto err_inval;
1523         }
1524
1525         if (fi->nh) {
1526                 err = fib_check_nexthop(fi->nh, cfg->fc_scope, extack);
1527                 if (err)
1528                         goto failure;
1529         } else if (cfg->fc_scope == RT_SCOPE_HOST) {
1530                 struct fib_nh *nh = fi->fib_nh;
1531
1532                 /* Local address is added. */
1533                 if (nhs != 1) {
1534                         NL_SET_ERR_MSG(extack,
1535                                        "Route with host scope can not have multiple nexthops");
1536                         goto err_inval;
1537                 }
1538                 if (nh->fib_nh_gw_family) {
1539                         NL_SET_ERR_MSG(extack,
1540                                        "Route with host scope can not have a gateway");
1541                         goto err_inval;
1542                 }
1543                 nh->fib_nh_scope = RT_SCOPE_NOWHERE;
1544                 nh->fib_nh_dev = dev_get_by_index(net, nh->fib_nh_oif);
1545                 err = -ENODEV;
1546                 if (!nh->fib_nh_dev)
1547                         goto failure;
1548                 netdev_tracker_alloc(nh->fib_nh_dev, &nh->fib_nh_dev_tracker,
1549                                      GFP_KERNEL);
1550         } else {
1551                 int linkdown = 0;
1552
1553                 change_nexthops(fi) {
1554                         err = fib_check_nh(cfg->fc_nlinfo.nl_net, nexthop_nh,
1555                                            cfg->fc_table, cfg->fc_scope,
1556                                            extack);
1557                         if (err != 0)
1558                                 goto failure;
1559                         if (nexthop_nh->fib_nh_flags & RTNH_F_LINKDOWN)
1560                                 linkdown++;
1561                 } endfor_nexthops(fi)
1562                 if (linkdown == fi->fib_nhs)
1563                         fi->fib_flags |= RTNH_F_LINKDOWN;
1564         }
1565
1566         if (fi->fib_prefsrc && !fib_valid_prefsrc(cfg, fi->fib_prefsrc)) {
1567                 NL_SET_ERR_MSG(extack, "Invalid prefsrc address");
1568                 goto err_inval;
1569         }
1570
1571         if (!fi->nh) {
1572                 change_nexthops(fi) {
1573                         fib_info_update_nhc_saddr(net, &nexthop_nh->nh_common,
1574                                                   fi->fib_scope);
1575                         if (nexthop_nh->fib_nh_gw_family == AF_INET6)
1576                                 fi->fib_nh_is_v6 = true;
1577                 } endfor_nexthops(fi)
1578
1579                 fib_rebalance(fi);
1580         }
1581
1582 link_it:
1583         ofi = fib_find_info(fi);
1584         if (ofi) {
1585                 /* fib_table_lookup() should not see @fi yet. */
1586                 fi->fib_dead = 1;
1587                 free_fib_info(fi);
1588                 refcount_inc(&ofi->fib_treeref);
1589                 return ofi;
1590         }
1591
1592         refcount_set(&fi->fib_treeref, 1);
1593         refcount_set(&fi->fib_clntref, 1);
1594         spin_lock_bh(&fib_info_lock);
1595         fib_info_cnt++;
1596         hlist_add_head(&fi->fib_hash,
1597                        &fib_info_hash[fib_info_hashfn(fi)]);
1598         if (fi->fib_prefsrc) {
1599                 struct hlist_head *head;
1600
1601                 head = fib_info_laddrhash_bucket(net, fi->fib_prefsrc);
1602                 hlist_add_head(&fi->fib_lhash, head);
1603         }
1604         if (fi->nh) {
1605                 list_add(&fi->nh_list, &nh->fi_list);
1606         } else {
1607                 change_nexthops(fi) {
1608                         struct hlist_head *head;
1609
1610                         if (!nexthop_nh->fib_nh_dev)
1611                                 continue;
1612                         head = fib_info_devhash_bucket(nexthop_nh->fib_nh_dev);
1613                         hlist_add_head(&nexthop_nh->nh_hash, head);
1614                 } endfor_nexthops(fi)
1615         }
1616         spin_unlock_bh(&fib_info_lock);
1617         return fi;
1618
1619 err_inval:
1620         err = -EINVAL;
1621
1622 failure:
1623         if (fi) {
1624                 /* fib_table_lookup() should not see @fi yet. */
1625                 fi->fib_dead = 1;
1626                 free_fib_info(fi);
1627         }
1628
1629         return ERR_PTR(err);
1630 }
1631
1632 int fib_nexthop_info(struct sk_buff *skb, const struct fib_nh_common *nhc,
1633                      u8 rt_family, unsigned char *flags, bool skip_oif)
1634 {
1635         if (nhc->nhc_flags & RTNH_F_DEAD)
1636                 *flags |= RTNH_F_DEAD;
1637
1638         if (nhc->nhc_flags & RTNH_F_LINKDOWN) {
1639                 *flags |= RTNH_F_LINKDOWN;
1640
1641                 rcu_read_lock();
1642                 switch (nhc->nhc_family) {
1643                 case AF_INET:
1644                         if (ip_ignore_linkdown(nhc->nhc_dev))
1645                                 *flags |= RTNH_F_DEAD;
1646                         break;
1647                 case AF_INET6:
1648                         if (ip6_ignore_linkdown(nhc->nhc_dev))
1649                                 *flags |= RTNH_F_DEAD;
1650                         break;
1651                 }
1652                 rcu_read_unlock();
1653         }
1654
1655         switch (nhc->nhc_gw_family) {
1656         case AF_INET:
1657                 if (nla_put_in_addr(skb, RTA_GATEWAY, nhc->nhc_gw.ipv4))
1658                         goto nla_put_failure;
1659                 break;
1660         case AF_INET6:
1661                 /* if gateway family does not match nexthop family
1662                  * gateway is encoded as RTA_VIA
1663                  */
1664                 if (rt_family != nhc->nhc_gw_family) {
1665                         int alen = sizeof(struct in6_addr);
1666                         struct nlattr *nla;
1667                         struct rtvia *via;
1668
1669                         nla = nla_reserve(skb, RTA_VIA, alen + 2);
1670                         if (!nla)
1671                                 goto nla_put_failure;
1672
1673                         via = nla_data(nla);
1674                         via->rtvia_family = AF_INET6;
1675                         memcpy(via->rtvia_addr, &nhc->nhc_gw.ipv6, alen);
1676                 } else if (nla_put_in6_addr(skb, RTA_GATEWAY,
1677                                             &nhc->nhc_gw.ipv6) < 0) {
1678                         goto nla_put_failure;
1679                 }
1680                 break;
1681         }
1682
1683         *flags |= (nhc->nhc_flags &
1684                    (RTNH_F_ONLINK | RTNH_F_OFFLOAD | RTNH_F_TRAP));
1685
1686         if (!skip_oif && nhc->nhc_dev &&
1687             nla_put_u32(skb, RTA_OIF, nhc->nhc_dev->ifindex))
1688                 goto nla_put_failure;
1689
1690         if (nhc->nhc_lwtstate &&
1691             lwtunnel_fill_encap(skb, nhc->nhc_lwtstate,
1692                                 RTA_ENCAP, RTA_ENCAP_TYPE) < 0)
1693                 goto nla_put_failure;
1694
1695         return 0;
1696
1697 nla_put_failure:
1698         return -EMSGSIZE;
1699 }
1700 EXPORT_SYMBOL_GPL(fib_nexthop_info);
1701
1702 #if IS_ENABLED(CONFIG_IP_ROUTE_MULTIPATH) || IS_ENABLED(CONFIG_IPV6)
1703 int fib_add_nexthop(struct sk_buff *skb, const struct fib_nh_common *nhc,
1704                     int nh_weight, u8 rt_family, u32 nh_tclassid)
1705 {
1706         const struct net_device *dev = nhc->nhc_dev;
1707         struct rtnexthop *rtnh;
1708         unsigned char flags = 0;
1709
1710         rtnh = nla_reserve_nohdr(skb, sizeof(*rtnh));
1711         if (!rtnh)
1712                 goto nla_put_failure;
1713
1714         rtnh->rtnh_hops = nh_weight - 1;
1715         rtnh->rtnh_ifindex = dev ? dev->ifindex : 0;
1716
1717         if (fib_nexthop_info(skb, nhc, rt_family, &flags, true) < 0)
1718                 goto nla_put_failure;
1719
1720         rtnh->rtnh_flags = flags;
1721
1722         if (nh_tclassid && nla_put_u32(skb, RTA_FLOW, nh_tclassid))
1723                 goto nla_put_failure;
1724
1725         /* length of rtnetlink header + attributes */
1726         rtnh->rtnh_len = nlmsg_get_pos(skb) - (void *)rtnh;
1727
1728         return 0;
1729
1730 nla_put_failure:
1731         return -EMSGSIZE;
1732 }
1733 EXPORT_SYMBOL_GPL(fib_add_nexthop);
1734 #endif
1735
1736 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1737 static int fib_add_multipath(struct sk_buff *skb, struct fib_info *fi)
1738 {
1739         struct nlattr *mp;
1740
1741         mp = nla_nest_start_noflag(skb, RTA_MULTIPATH);
1742         if (!mp)
1743                 goto nla_put_failure;
1744
1745         if (unlikely(fi->nh)) {
1746                 if (nexthop_mpath_fill_node(skb, fi->nh, AF_INET) < 0)
1747                         goto nla_put_failure;
1748                 goto mp_end;
1749         }
1750
1751         for_nexthops(fi) {
1752                 u32 nh_tclassid = 0;
1753 #ifdef CONFIG_IP_ROUTE_CLASSID
1754                 nh_tclassid = nh->nh_tclassid;
1755 #endif
1756                 if (fib_add_nexthop(skb, &nh->nh_common, nh->fib_nh_weight,
1757                                     AF_INET, nh_tclassid) < 0)
1758                         goto nla_put_failure;
1759         } endfor_nexthops(fi);
1760
1761 mp_end:
1762         nla_nest_end(skb, mp);
1763
1764         return 0;
1765
1766 nla_put_failure:
1767         return -EMSGSIZE;
1768 }
1769 #else
1770 static int fib_add_multipath(struct sk_buff *skb, struct fib_info *fi)
1771 {
1772         return 0;
1773 }
1774 #endif
1775
1776 int fib_dump_info(struct sk_buff *skb, u32 portid, u32 seq, int event,
1777                   const struct fib_rt_info *fri, unsigned int flags)
1778 {
1779         unsigned int nhs = fib_info_num_path(fri->fi);
1780         struct fib_info *fi = fri->fi;
1781         u32 tb_id = fri->tb_id;
1782         struct nlmsghdr *nlh;
1783         struct rtmsg *rtm;
1784
1785         nlh = nlmsg_put(skb, portid, seq, event, sizeof(*rtm), flags);
1786         if (!nlh)
1787                 return -EMSGSIZE;
1788
1789         rtm = nlmsg_data(nlh);
1790         rtm->rtm_family = AF_INET;
1791         rtm->rtm_dst_len = fri->dst_len;
1792         rtm->rtm_src_len = 0;
1793         rtm->rtm_tos = inet_dscp_to_dsfield(fri->dscp);
1794         if (tb_id < 256)
1795                 rtm->rtm_table = tb_id;
1796         else
1797                 rtm->rtm_table = RT_TABLE_COMPAT;
1798         if (nla_put_u32(skb, RTA_TABLE, tb_id))
1799                 goto nla_put_failure;
1800         rtm->rtm_type = fri->type;
1801         rtm->rtm_flags = fi->fib_flags;
1802         rtm->rtm_scope = fi->fib_scope;
1803         rtm->rtm_protocol = fi->fib_protocol;
1804
1805         if (rtm->rtm_dst_len &&
1806             nla_put_in_addr(skb, RTA_DST, fri->dst))
1807                 goto nla_put_failure;
1808         if (fi->fib_priority &&
1809             nla_put_u32(skb, RTA_PRIORITY, fi->fib_priority))
1810                 goto nla_put_failure;
1811         if (rtnetlink_put_metrics(skb, fi->fib_metrics->metrics) < 0)
1812                 goto nla_put_failure;
1813
1814         if (fi->fib_prefsrc &&
1815             nla_put_in_addr(skb, RTA_PREFSRC, fi->fib_prefsrc))
1816                 goto nla_put_failure;
1817
1818         if (fi->nh) {
1819                 if (nla_put_u32(skb, RTA_NH_ID, fi->nh->id))
1820                         goto nla_put_failure;
1821                 if (nexthop_is_blackhole(fi->nh))
1822                         rtm->rtm_type = RTN_BLACKHOLE;
1823                 if (!READ_ONCE(fi->fib_net->ipv4.sysctl_nexthop_compat_mode))
1824                         goto offload;
1825         }
1826
1827         if (nhs == 1) {
1828                 const struct fib_nh_common *nhc = fib_info_nhc(fi, 0);
1829                 unsigned char flags = 0;
1830
1831                 if (fib_nexthop_info(skb, nhc, AF_INET, &flags, false) < 0)
1832                         goto nla_put_failure;
1833
1834                 rtm->rtm_flags = flags;
1835 #ifdef CONFIG_IP_ROUTE_CLASSID
1836                 if (nhc->nhc_family == AF_INET) {
1837                         struct fib_nh *nh;
1838
1839                         nh = container_of(nhc, struct fib_nh, nh_common);
1840                         if (nh->nh_tclassid &&
1841                             nla_put_u32(skb, RTA_FLOW, nh->nh_tclassid))
1842                                 goto nla_put_failure;
1843                 }
1844 #endif
1845         } else {
1846                 if (fib_add_multipath(skb, fi) < 0)
1847                         goto nla_put_failure;
1848         }
1849
1850 offload:
1851         if (fri->offload)
1852                 rtm->rtm_flags |= RTM_F_OFFLOAD;
1853         if (fri->trap)
1854                 rtm->rtm_flags |= RTM_F_TRAP;
1855         if (fri->offload_failed)
1856                 rtm->rtm_flags |= RTM_F_OFFLOAD_FAILED;
1857
1858         nlmsg_end(skb, nlh);
1859         return 0;
1860
1861 nla_put_failure:
1862         nlmsg_cancel(skb, nlh);
1863         return -EMSGSIZE;
1864 }
1865
1866 /*
1867  * Update FIB if:
1868  * - local address disappeared -> we must delete all the entries
1869  *   referring to it.
1870  * - device went down -> we must shutdown all nexthops going via it.
1871  */
1872 int fib_sync_down_addr(struct net_device *dev, __be32 local)
1873 {
1874         int tb_id = l3mdev_fib_table(dev) ? : RT_TABLE_MAIN;
1875         struct net *net = dev_net(dev);
1876         struct hlist_head *head;
1877         struct fib_info *fi;
1878         int ret = 0;
1879
1880         if (!fib_info_laddrhash || local == 0)
1881                 return 0;
1882
1883         head = fib_info_laddrhash_bucket(net, local);
1884         hlist_for_each_entry(fi, head, fib_lhash) {
1885                 if (!net_eq(fi->fib_net, net) ||
1886                     fi->fib_tb_id != tb_id)
1887                         continue;
1888                 if (fi->fib_prefsrc == local) {
1889                         fi->fib_flags |= RTNH_F_DEAD;
1890                         fi->pfsrc_removed = true;
1891                         ret++;
1892                 }
1893         }
1894         return ret;
1895 }
1896
1897 static int call_fib_nh_notifiers(struct fib_nh *nh,
1898                                  enum fib_event_type event_type)
1899 {
1900         bool ignore_link_down = ip_ignore_linkdown(nh->fib_nh_dev);
1901         struct fib_nh_notifier_info info = {
1902                 .fib_nh = nh,
1903         };
1904
1905         switch (event_type) {
1906         case FIB_EVENT_NH_ADD:
1907                 if (nh->fib_nh_flags & RTNH_F_DEAD)
1908                         break;
1909                 if (ignore_link_down && nh->fib_nh_flags & RTNH_F_LINKDOWN)
1910                         break;
1911                 return call_fib4_notifiers(dev_net(nh->fib_nh_dev), event_type,
1912                                            &info.info);
1913         case FIB_EVENT_NH_DEL:
1914                 if ((ignore_link_down && nh->fib_nh_flags & RTNH_F_LINKDOWN) ||
1915                     (nh->fib_nh_flags & RTNH_F_DEAD))
1916                         return call_fib4_notifiers(dev_net(nh->fib_nh_dev),
1917                                                    event_type, &info.info);
1918                 break;
1919         default:
1920                 break;
1921         }
1922
1923         return NOTIFY_DONE;
1924 }
1925
1926 /* Update the PMTU of exceptions when:
1927  * - the new MTU of the first hop becomes smaller than the PMTU
1928  * - the old MTU was the same as the PMTU, and it limited discovery of
1929  *   larger MTUs on the path. With that limit raised, we can now
1930  *   discover larger MTUs
1931  * A special case is locked exceptions, for which the PMTU is smaller
1932  * than the minimal accepted PMTU:
1933  * - if the new MTU is greater than the PMTU, don't make any change
1934  * - otherwise, unlock and set PMTU
1935  */
1936 void fib_nhc_update_mtu(struct fib_nh_common *nhc, u32 new, u32 orig)
1937 {
1938         struct fnhe_hash_bucket *bucket;
1939         int i;
1940
1941         bucket = rcu_dereference_protected(nhc->nhc_exceptions, 1);
1942         if (!bucket)
1943                 return;
1944
1945         for (i = 0; i < FNHE_HASH_SIZE; i++) {
1946                 struct fib_nh_exception *fnhe;
1947
1948                 for (fnhe = rcu_dereference_protected(bucket[i].chain, 1);
1949                      fnhe;
1950                      fnhe = rcu_dereference_protected(fnhe->fnhe_next, 1)) {
1951                         if (fnhe->fnhe_mtu_locked) {
1952                                 if (new <= fnhe->fnhe_pmtu) {
1953                                         fnhe->fnhe_pmtu = new;
1954                                         fnhe->fnhe_mtu_locked = false;
1955                                 }
1956                         } else if (new < fnhe->fnhe_pmtu ||
1957                                    orig == fnhe->fnhe_pmtu) {
1958                                 fnhe->fnhe_pmtu = new;
1959                         }
1960                 }
1961         }
1962 }
1963
1964 void fib_sync_mtu(struct net_device *dev, u32 orig_mtu)
1965 {
1966         struct hlist_head *head = fib_info_devhash_bucket(dev);
1967         struct fib_nh *nh;
1968
1969         hlist_for_each_entry(nh, head, nh_hash) {
1970                 if (nh->fib_nh_dev == dev)
1971                         fib_nhc_update_mtu(&nh->nh_common, dev->mtu, orig_mtu);
1972         }
1973 }
1974
1975 /* Event              force Flags           Description
1976  * NETDEV_CHANGE      0     LINKDOWN        Carrier OFF, not for scope host
1977  * NETDEV_DOWN        0     LINKDOWN|DEAD   Link down, not for scope host
1978  * NETDEV_DOWN        1     LINKDOWN|DEAD   Last address removed
1979  * NETDEV_UNREGISTER  1     LINKDOWN|DEAD   Device removed
1980  *
1981  * only used when fib_nh is built into fib_info
1982  */
1983 int fib_sync_down_dev(struct net_device *dev, unsigned long event, bool force)
1984 {
1985         struct hlist_head *head = fib_info_devhash_bucket(dev);
1986         struct fib_info *prev_fi = NULL;
1987         int scope = RT_SCOPE_NOWHERE;
1988         struct fib_nh *nh;
1989         int ret = 0;
1990
1991         if (force)
1992                 scope = -1;
1993
1994         hlist_for_each_entry(nh, head, nh_hash) {
1995                 struct fib_info *fi = nh->nh_parent;
1996                 int dead;
1997
1998                 BUG_ON(!fi->fib_nhs);
1999                 if (nh->fib_nh_dev != dev || fi == prev_fi)
2000                         continue;
2001                 prev_fi = fi;
2002                 dead = 0;
2003                 change_nexthops(fi) {
2004                         if (nexthop_nh->fib_nh_flags & RTNH_F_DEAD)
2005                                 dead++;
2006                         else if (nexthop_nh->fib_nh_dev == dev &&
2007                                  nexthop_nh->fib_nh_scope != scope) {
2008                                 switch (event) {
2009                                 case NETDEV_DOWN:
2010                                 case NETDEV_UNREGISTER:
2011                                         nexthop_nh->fib_nh_flags |= RTNH_F_DEAD;
2012                                         fallthrough;
2013                                 case NETDEV_CHANGE:
2014                                         nexthop_nh->fib_nh_flags |= RTNH_F_LINKDOWN;
2015                                         break;
2016                                 }
2017                                 call_fib_nh_notifiers(nexthop_nh,
2018                                                       FIB_EVENT_NH_DEL);
2019                                 dead++;
2020                         }
2021 #ifdef CONFIG_IP_ROUTE_MULTIPATH
2022                         if (event == NETDEV_UNREGISTER &&
2023                             nexthop_nh->fib_nh_dev == dev) {
2024                                 dead = fi->fib_nhs;
2025                                 break;
2026                         }
2027 #endif
2028                 } endfor_nexthops(fi)
2029                 if (dead == fi->fib_nhs) {
2030                         switch (event) {
2031                         case NETDEV_DOWN:
2032                         case NETDEV_UNREGISTER:
2033                                 fi->fib_flags |= RTNH_F_DEAD;
2034                                 fallthrough;
2035                         case NETDEV_CHANGE:
2036                                 fi->fib_flags |= RTNH_F_LINKDOWN;
2037                                 break;
2038                         }
2039                         ret++;
2040                 }
2041
2042                 fib_rebalance(fi);
2043         }
2044
2045         return ret;
2046 }
2047
2048 /* Must be invoked inside of an RCU protected region.  */
2049 static void fib_select_default(const struct flowi4 *flp, struct fib_result *res)
2050 {
2051         struct fib_info *fi = NULL, *last_resort = NULL;
2052         struct hlist_head *fa_head = res->fa_head;
2053         struct fib_table *tb = res->table;
2054         u8 slen = 32 - res->prefixlen;
2055         int order = -1, last_idx = -1;
2056         struct fib_alias *fa, *fa1 = NULL;
2057         u32 last_prio = res->fi->fib_priority;
2058         dscp_t last_dscp = 0;
2059
2060         hlist_for_each_entry_rcu(fa, fa_head, fa_list) {
2061                 struct fib_info *next_fi = fa->fa_info;
2062                 struct fib_nh_common *nhc;
2063
2064                 if (fa->fa_slen != slen)
2065                         continue;
2066                 if (fa->fa_dscp &&
2067                     fa->fa_dscp != inet_dsfield_to_dscp(flp->flowi4_tos))
2068                         continue;
2069                 if (fa->tb_id != tb->tb_id)
2070                         continue;
2071                 if (next_fi->fib_priority > last_prio &&
2072                     fa->fa_dscp == last_dscp) {
2073                         if (last_dscp)
2074                                 continue;
2075                         break;
2076                 }
2077                 if (next_fi->fib_flags & RTNH_F_DEAD)
2078                         continue;
2079                 last_dscp = fa->fa_dscp;
2080                 last_prio = next_fi->fib_priority;
2081
2082                 if (next_fi->fib_scope != res->scope ||
2083                     fa->fa_type != RTN_UNICAST)
2084                         continue;
2085
2086                 nhc = fib_info_nhc(next_fi, 0);
2087                 if (!nhc->nhc_gw_family || nhc->nhc_scope != RT_SCOPE_LINK)
2088                         continue;
2089
2090                 fib_alias_accessed(fa);
2091
2092                 if (!fi) {
2093                         if (next_fi != res->fi)
2094                                 break;
2095                         fa1 = fa;
2096                 } else if (!fib_detect_death(fi, order, &last_resort,
2097                                              &last_idx, fa1->fa_default)) {
2098                         fib_result_assign(res, fi);
2099                         fa1->fa_default = order;
2100                         goto out;
2101                 }
2102                 fi = next_fi;
2103                 order++;
2104         }
2105
2106         if (order <= 0 || !fi) {
2107                 if (fa1)
2108                         fa1->fa_default = -1;
2109                 goto out;
2110         }
2111
2112         if (!fib_detect_death(fi, order, &last_resort, &last_idx,
2113                               fa1->fa_default)) {
2114                 fib_result_assign(res, fi);
2115                 fa1->fa_default = order;
2116                 goto out;
2117         }
2118
2119         if (last_idx >= 0)
2120                 fib_result_assign(res, last_resort);
2121         fa1->fa_default = last_idx;
2122 out:
2123         return;
2124 }
2125
2126 /*
2127  * Dead device goes up. We wake up dead nexthops.
2128  * It takes sense only on multipath routes.
2129  *
2130  * only used when fib_nh is built into fib_info
2131  */
2132 int fib_sync_up(struct net_device *dev, unsigned char nh_flags)
2133 {
2134         struct fib_info *prev_fi;
2135         struct hlist_head *head;
2136         struct fib_nh *nh;
2137         int ret;
2138
2139         if (!(dev->flags & IFF_UP))
2140                 return 0;
2141
2142         if (nh_flags & RTNH_F_DEAD) {
2143                 unsigned int flags = dev_get_flags(dev);
2144
2145                 if (flags & (IFF_RUNNING | IFF_LOWER_UP))
2146                         nh_flags |= RTNH_F_LINKDOWN;
2147         }
2148
2149         prev_fi = NULL;
2150         head = fib_info_devhash_bucket(dev);
2151         ret = 0;
2152
2153         hlist_for_each_entry(nh, head, nh_hash) {
2154                 struct fib_info *fi = nh->nh_parent;
2155                 int alive;
2156
2157                 BUG_ON(!fi->fib_nhs);
2158                 if (nh->fib_nh_dev != dev || fi == prev_fi)
2159                         continue;
2160
2161                 prev_fi = fi;
2162                 alive = 0;
2163                 change_nexthops(fi) {
2164                         if (!(nexthop_nh->fib_nh_flags & nh_flags)) {
2165                                 alive++;
2166                                 continue;
2167                         }
2168                         if (!nexthop_nh->fib_nh_dev ||
2169                             !(nexthop_nh->fib_nh_dev->flags & IFF_UP))
2170                                 continue;
2171                         if (nexthop_nh->fib_nh_dev != dev ||
2172                             !__in_dev_get_rtnl(dev))
2173                                 continue;
2174                         alive++;
2175                         nexthop_nh->fib_nh_flags &= ~nh_flags;
2176                         call_fib_nh_notifiers(nexthop_nh, FIB_EVENT_NH_ADD);
2177                 } endfor_nexthops(fi)
2178
2179                 if (alive > 0) {
2180                         fi->fib_flags &= ~nh_flags;
2181                         ret++;
2182                 }
2183
2184                 fib_rebalance(fi);
2185         }
2186
2187         return ret;
2188 }
2189
2190 #ifdef CONFIG_IP_ROUTE_MULTIPATH
2191 static bool fib_good_nh(const struct fib_nh *nh)
2192 {
2193         int state = NUD_REACHABLE;
2194
2195         if (nh->fib_nh_scope == RT_SCOPE_LINK) {
2196                 struct neighbour *n;
2197
2198                 rcu_read_lock();
2199
2200                 if (likely(nh->fib_nh_gw_family == AF_INET))
2201                         n = __ipv4_neigh_lookup_noref(nh->fib_nh_dev,
2202                                                    (__force u32)nh->fib_nh_gw4);
2203                 else if (nh->fib_nh_gw_family == AF_INET6)
2204                         n = __ipv6_neigh_lookup_noref_stub(nh->fib_nh_dev,
2205                                                            &nh->fib_nh_gw6);
2206                 else
2207                         n = NULL;
2208                 if (n)
2209                         state = READ_ONCE(n->nud_state);
2210
2211                 rcu_read_unlock();
2212         }
2213
2214         return !!(state & NUD_VALID);
2215 }
2216
2217 void fib_select_multipath(struct fib_result *res, int hash)
2218 {
2219         struct fib_info *fi = res->fi;
2220         struct net *net = fi->fib_net;
2221         bool first = false;
2222
2223         if (unlikely(res->fi->nh)) {
2224                 nexthop_path_fib_result(res, hash);
2225                 return;
2226         }
2227
2228         change_nexthops(fi) {
2229                 if (READ_ONCE(net->ipv4.sysctl_fib_multipath_use_neigh)) {
2230                         if (!fib_good_nh(nexthop_nh))
2231                                 continue;
2232                         if (!first) {
2233                                 res->nh_sel = nhsel;
2234                                 res->nhc = &nexthop_nh->nh_common;
2235                                 first = true;
2236                         }
2237                 }
2238
2239                 if (hash > atomic_read(&nexthop_nh->fib_nh_upper_bound))
2240                         continue;
2241
2242                 res->nh_sel = nhsel;
2243                 res->nhc = &nexthop_nh->nh_common;
2244                 return;
2245         } endfor_nexthops(fi);
2246 }
2247 #endif
2248
2249 void fib_select_path(struct net *net, struct fib_result *res,
2250                      struct flowi4 *fl4, const struct sk_buff *skb)
2251 {
2252         if (fl4->flowi4_oif)
2253                 goto check_saddr;
2254
2255 #ifdef CONFIG_IP_ROUTE_MULTIPATH
2256         if (fib_info_num_path(res->fi) > 1) {
2257                 int h = fib_multipath_hash(net, fl4, skb, NULL);
2258
2259                 fib_select_multipath(res, h);
2260         }
2261         else
2262 #endif
2263         if (!res->prefixlen &&
2264             res->table->tb_num_default > 1 &&
2265             res->type == RTN_UNICAST)
2266                 fib_select_default(fl4, res);
2267
2268 check_saddr:
2269         if (!fl4->saddr)
2270                 fl4->saddr = fib_result_prefsrc(net, res);
2271 }