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
  34 #include <net/arp.h>
  35 #include <net/ip.h>
  36 #include <net/protocol.h>
  37 #include <net/route.h>
  38 #include <net/tcp.h>
  39 #include <net/sock.h>
  40 #include <net/ip_fib.h>
  41 #include <net/ip6_fib.h>
  42 #include <net/nexthop.h>
  43 #include <net/netlink.h>
  44 #include <net/rtnh.h>
  45 #include <net/lwtunnel.h>
  46 #include <net/fib_notifier.h>
  47 #include <net/addrconf.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_hash_bits;
  56 static unsigned int fib_info_cnt;
  57
  58 #define DEVINDEX_HASHBITS 8
  59 #define DEVINDEX_HASHSIZE (1U << DEVINDEX_HASHBITS)
  60 static struct hlist_head fib_info_devhash[DEVINDEX_HASHSIZE];
  61
  62 /* for_nexthops and change_nexthops only used when nexthop object
  63  * is not set in a fib_info. The logic within can reference fib_nh.
  64  */
  65 #ifdef CONFIG_IP_ROUTE_MULTIPATH
  66
  67 #define for_nexthops(fi) {                                              \
  68         int nhsel; const struct fib_nh *nh;                             \
  69         for (nhsel = 0, nh = (fi)->fib_nh;                              \
  70              nhsel < fib_info_num_path((fi));                           \
  71              nh++, nhsel++)
  72
  73 #define change_nexthops(fi) {                                           \
  74         int nhsel; struct fib_nh *nexthop_nh;                           \
  75         for (nhsel = 0, nexthop_nh = (struct fib_nh *)((fi)->fib_nh);   \
  76              nhsel < fib_info_num_path((fi));                           \
  77              nexthop_nh++, nhsel++)
  78
  79 #else /* CONFIG_IP_ROUTE_MULTIPATH */
  80
  81 /* Hope, that gcc will optimize it to get rid of dummy loop */
  82
  83 #define for_nexthops(fi) {                                              \
  84         int nhsel; const struct fib_nh *nh = (fi)->fib_nh;              \
  85         for (nhsel = 0; nhsel < 1; nhsel++)
  86
  87 #define change_nexthops(fi) {                                           \
  88         int nhsel;                                                      \
  89         struct fib_nh *nexthop_nh = (struct fib_nh *)((fi)->fib_nh);    \
  90         for (nhsel = 0; nhsel < 1; nhsel++)
  91
  92 #endif /* CONFIG_IP_ROUTE_MULTIPATH */
  93
  94 #define endfor_nexthops(fi) }
  95
  96
  97 const struct fib_prop fib_props[RTN_MAX + 1] = {
  98         [RTN_UNSPEC] = {
  99                 .error  = 0,
 100                 .scope  = RT_SCOPE_NOWHERE,
 101         },
 102         [RTN_UNICAST] = {
 103                 .error  = 0,
 104                 .scope  = RT_SCOPE_UNIVERSE,
 105         },
 106         [RTN_LOCAL] = {
 107                 .error  = 0,
 108                 .scope  = RT_SCOPE_HOST,
 109         },
 110         [RTN_BROADCAST] = {
 111                 .error  = 0,
 112                 .scope  = RT_SCOPE_LINK,
 113         },
 114         [RTN_ANYCAST] = {
 115                 .error  = 0,
 116                 .scope  = RT_SCOPE_LINK,
 117         },
 118         [RTN_MULTICAST] = {
 119                 .error  = 0,
 120                 .scope  = RT_SCOPE_UNIVERSE,
 121         },
 122         [RTN_BLACKHOLE] = {
 123                 .error  = -EINVAL,
 124                 .scope  = RT_SCOPE_UNIVERSE,
 125         },
 126         [RTN_UNREACHABLE] = {
 127                 .error  = -EHOSTUNREACH,
 128                 .scope  = RT_SCOPE_UNIVERSE,
 129         },
 130         [RTN_PROHIBIT] = {
 131                 .error  = -EACCES,
 132                 .scope  = RT_SCOPE_UNIVERSE,
 133         },
 134         [RTN_THROW] = {
 135                 .error  = -EAGAIN,
 136                 .scope  = RT_SCOPE_UNIVERSE,
 137         },
 138         [RTN_NAT] = {
 139                 .error  = -EINVAL,
 140                 .scope  = RT_SCOPE_NOWHERE,
 141         },
 142         [RTN_XRESOLVE] = {
 143                 .error  = -EINVAL,
 144                 .scope  = RT_SCOPE_NOWHERE,
 145         },
 146 };
 147
 148 static void rt_fibinfo_free(struct rtable __rcu **rtp)
 149 {
 150         struct rtable *rt = rcu_dereference_protected(*rtp, 1);
 151
 152         if (!rt)
 153                 return;
 154
 155         /* Not even needed : RCU_INIT_POINTER(*rtp, NULL);
 156          * because we waited an RCU grace period before calling
 157          * free_fib_info_rcu()
 158          */
 159
 160         dst_dev_put(&rt->dst);
 161         dst_release_immediate(&rt->dst);
 162 }
 163
 164 static void free_nh_exceptions(struct fib_nh_common *nhc)
 165 {
 166         struct fnhe_hash_bucket *hash;
 167         int i;
 168
 169         hash = rcu_dereference_protected(nhc->nhc_exceptions, 1);
 170         if (!hash)
 171                 return;
 172         for (i = 0; i < FNHE_HASH_SIZE; i++) {
 173                 struct fib_nh_exception *fnhe;
 174
 175                 fnhe = rcu_dereference_protected(hash[i].chain, 1);
 176                 while (fnhe) {
 177                         struct fib_nh_exception *next;
 178
 179                         next = rcu_dereference_protected(fnhe->fnhe_next, 1);
 180
 181                         rt_fibinfo_free(&fnhe->fnhe_rth_input);
 182                         rt_fibinfo_free(&fnhe->fnhe_rth_output);
 183
 184                         kfree(fnhe);
 185
 186                         fnhe = next;
 187                 }
 188         }
 189         kfree(hash);
 190 }
 191
 192 static void rt_fibinfo_free_cpus(struct rtable __rcu * __percpu *rtp)
 193 {
 194         int cpu;
 195
 196         if (!rtp)
 197                 return;
 198
 199         for_each_possible_cpu(cpu) {
 200                 struct rtable *rt;
 201
 202                 rt = rcu_dereference_protected(*per_cpu_ptr(rtp, cpu), 1);
 203                 if (rt) {
 204                         dst_dev_put(&rt->dst);
 205                         dst_release_immediate(&rt->dst);
 206                 }
 207         }
 208         free_percpu(rtp);
 209 }
 210
 211 void fib_nh_common_release(struct fib_nh_common *nhc)
 212 {
 213         dev_put_track(nhc->nhc_dev, &nhc->nhc_dev_tracker);
 214         lwtstate_put(nhc->nhc_lwtstate);
 215         rt_fibinfo_free_cpus(nhc->nhc_pcpu_rth_output);
 216         rt_fibinfo_free(&nhc->nhc_rth_input);
 217         free_nh_exceptions(nhc);
 218 }
 219 EXPORT_SYMBOL_GPL(fib_nh_common_release);
 220
 221 void fib_nh_release(struct net *net, struct fib_nh *fib_nh)
 222 {
 223 #ifdef CONFIG_IP_ROUTE_CLASSID
 224         if (fib_nh->nh_tclassid)
 225                 atomic_dec(&net->ipv4.fib_num_tclassid_users);
 226 #endif
 227         fib_nh_common_release(&fib_nh->nh_common);
 228 }
 229
 230 /* Release a nexthop info record */
 231 static void free_fib_info_rcu(struct rcu_head *head)
 232 {
 233         struct fib_info *fi = container_of(head, struct fib_info, rcu);
 234
 235         if (fi->nh) {
 236                 nexthop_put(fi->nh);
 237         } else {
 238                 change_nexthops(fi) {
 239                         fib_nh_release(fi->fib_net, nexthop_nh);
 240                 } endfor_nexthops(fi);
 241         }
 242
 243         ip_fib_metrics_put(fi->fib_metrics);
 244
 245         kfree(fi);
 246 }
 247
 248 void free_fib_info(struct fib_info *fi)
 249 {
 250         if (fi->fib_dead == 0) {
 251                 pr_warn("Freeing alive fib_info %p\n", fi);
 252                 return;
 253         }
 254
 255         call_rcu(&fi->rcu, free_fib_info_rcu);
 256 }
 257 EXPORT_SYMBOL_GPL(free_fib_info);
 258
 259 void fib_release_info(struct fib_info *fi)
 260 {
 261         spin_lock_bh(&fib_info_lock);
 262         if (fi && refcount_dec_and_test(&fi->fib_treeref)) {
 263                 hlist_del(&fi->fib_hash);
 264
 265                 /* Paired with READ_ONCE() in fib_create_info(). */
 266                 WRITE_ONCE(fib_info_cnt, fib_info_cnt - 1);
 267
 268                 if (fi->fib_prefsrc)
 269                         hlist_del(&fi->fib_lhash);
 270                 if (fi->nh) {
 271                         list_del(&fi->nh_list);
 272                 } else {
 273                         change_nexthops(fi) {
 274                                 if (!nexthop_nh->fib_nh_dev)
 275                                         continue;
 276                                 hlist_del(&nexthop_nh->nh_hash);
 277                         } endfor_nexthops(fi)
 278                 }
 279                 fi->fib_dead = 1;
 280                 fib_info_put(fi);
 281         }
 282         spin_unlock_bh(&fib_info_lock);
 283 }
 284
 285 static inline int nh_comp(struct fib_info *fi, struct fib_info *ofi)
 286 {
 287         const struct fib_nh *onh;
 288
 289         if (fi->nh || ofi->nh)
 290                 return nexthop_cmp(fi->nh, ofi->nh) ? 0 : -1;
 291
 292         if (ofi->fib_nhs == 0)
 293                 return 0;
 294
 295         for_nexthops(fi) {
 296                 onh = fib_info_nh(ofi, nhsel);
 297
 298                 if (nh->fib_nh_oif != onh->fib_nh_oif ||
 299                     nh->fib_nh_gw_family != onh->fib_nh_gw_family ||
 300                     nh->fib_nh_scope != onh->fib_nh_scope ||
 301 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 302                     nh->fib_nh_weight != onh->fib_nh_weight ||
 303 #endif
 304 #ifdef CONFIG_IP_ROUTE_CLASSID
 305                     nh->nh_tclassid != onh->nh_tclassid ||
 306 #endif
 307                     lwtunnel_cmp_encap(nh->fib_nh_lws, onh->fib_nh_lws) ||
 308                     ((nh->fib_nh_flags ^ onh->fib_nh_flags) & ~RTNH_COMPARE_MASK))
 309                         return -1;
 310
 311                 if (nh->fib_nh_gw_family == AF_INET &&
 312                     nh->fib_nh_gw4 != onh->fib_nh_gw4)
 313                         return -1;
 314
 315                 if (nh->fib_nh_gw_family == AF_INET6 &&
 316                     ipv6_addr_cmp(&nh->fib_nh_gw6, &onh->fib_nh_gw6))
 317                         return -1;
 318         } endfor_nexthops(fi);
 319         return 0;
 320 }
 321
 322 static inline unsigned int fib_devindex_hashfn(unsigned int val)
 323 {
 324         return hash_32(val, DEVINDEX_HASHBITS);
 325 }
 326
 327 static struct hlist_head *
 328 fib_info_devhash_bucket(const struct net_device *dev)
 329 {
 330         u32 val = net_hash_mix(dev_net(dev)) ^ dev->ifindex;
 331
 332         return &fib_info_devhash[fib_devindex_hashfn(val)];
 333 }
 334
 335 static unsigned int fib_info_hashfn_1(int init_val, u8 protocol, u8 scope,
 336                                       u32 prefsrc, u32 priority)
 337 {
 338         unsigned int val = init_val;
 339
 340         val ^= (protocol << 8) | scope;
 341         val ^= prefsrc;
 342         val ^= priority;
 343
 344         return val;
 345 }
 346
 347 static unsigned int fib_info_hashfn_result(unsigned int val)
 348 {
 349         unsigned int mask = (fib_info_hash_size - 1);
 350
 351         return (val ^ (val >> 7) ^ (val >> 12)) & mask;
 352 }
 353
 354 static inline unsigned int fib_info_hashfn(struct fib_info *fi)
 355 {
 356         unsigned int val;
 357
 358         val = fib_info_hashfn_1(fi->fib_nhs, fi->fib_protocol,
 359                                 fi->fib_scope, (__force u32)fi->fib_prefsrc,
 360                                 fi->fib_priority);
 361
 362         if (fi->nh) {
 363                 val ^= fib_devindex_hashfn(fi->nh->id);
 364         } else {
 365                 for_nexthops(fi) {
 366                         val ^= fib_devindex_hashfn(nh->fib_nh_oif);
 367                 } endfor_nexthops(fi)
 368         }
 369
 370         return fib_info_hashfn_result(val);
 371 }
 372
 373 /* no metrics, only nexthop id */
 374 static struct fib_info *fib_find_info_nh(struct net *net,
 375                                          const struct fib_config *cfg)
 376 {
 377         struct hlist_head *head;
 378         struct fib_info *fi;
 379         unsigned int hash;
 380
 381         hash = fib_info_hashfn_1(fib_devindex_hashfn(cfg->fc_nh_id),
 382                                  cfg->fc_protocol, cfg->fc_scope,
 383                                  (__force u32)cfg->fc_prefsrc,
 384                                  cfg->fc_priority);
 385         hash = fib_info_hashfn_result(hash);
 386         head = &fib_info_hash[hash];
 387
 388         hlist_for_each_entry(fi, head, fib_hash) {
 389                 if (!net_eq(fi->fib_net, net))
 390                         continue;
 391                 if (!fi->nh || fi->nh->id != cfg->fc_nh_id)
 392                         continue;
 393                 if (cfg->fc_protocol == fi->fib_protocol &&
 394                     cfg->fc_scope == fi->fib_scope &&
 395                     cfg->fc_prefsrc == fi->fib_prefsrc &&
 396                     cfg->fc_priority == fi->fib_priority &&
 397                     cfg->fc_type == fi->fib_type &&
 398                     cfg->fc_table == fi->fib_tb_id &&
 399                     !((cfg->fc_flags ^ fi->fib_flags) & ~RTNH_COMPARE_MASK))
 400                         return fi;
 401         }
 402
 403         return NULL;
 404 }
 405
 406 static struct fib_info *fib_find_info(struct fib_info *nfi)
 407 {
 408         struct hlist_head *head;
 409         struct fib_info *fi;
 410         unsigned int hash;
 411
 412         hash = fib_info_hashfn(nfi);
 413         head = &fib_info_hash[hash];
 414
 415         hlist_for_each_entry(fi, head, fib_hash) {
 416                 if (!net_eq(fi->fib_net, nfi->fib_net))
 417                         continue;
 418                 if (fi->fib_nhs != nfi->fib_nhs)
 419                         continue;
 420                 if (nfi->fib_protocol == fi->fib_protocol &&
 421                     nfi->fib_scope == fi->fib_scope &&
 422                     nfi->fib_prefsrc == fi->fib_prefsrc &&
 423                     nfi->fib_priority == fi->fib_priority &&
 424                     nfi->fib_type == fi->fib_type &&
 425                     memcmp(nfi->fib_metrics, fi->fib_metrics,
 426                            sizeof(u32) * RTAX_MAX) == 0 &&
 427                     !((nfi->fib_flags ^ fi->fib_flags) & ~RTNH_COMPARE_MASK) &&
 428                     nh_comp(fi, nfi) == 0)
 429                         return fi;
 430         }
 431
 432         return NULL;
 433 }
 434
 435 /* Check, that the gateway is already configured.
 436  * Used only by redirect accept routine.
 437  */
 438 int ip_fib_check_default(__be32 gw, struct net_device *dev)
 439 {
 440         struct hlist_head *head;
 441         struct fib_nh *nh;
 442
 443         spin_lock(&fib_info_lock);
 444
 445         head = fib_info_devhash_bucket(dev);
 446
 447         hlist_for_each_entry(nh, head, nh_hash) {
 448                 if (nh->fib_nh_dev == dev &&
 449                     nh->fib_nh_gw4 == gw &&
 450                     !(nh->fib_nh_flags & RTNH_F_DEAD)) {
 451                         spin_unlock(&fib_info_lock);
 452                         return 0;
 453                 }
 454         }
 455
 456         spin_unlock(&fib_info_lock);
 457
 458         return -1;
 459 }
 460
 461 size_t fib_nlmsg_size(struct fib_info *fi)
 462 {
 463         size_t payload = NLMSG_ALIGN(sizeof(struct rtmsg))
 464                          + nla_total_size(4) /* RTA_TABLE */
 465                          + nla_total_size(4) /* RTA_DST */
 466                          + nla_total_size(4) /* RTA_PRIORITY */
 467                          + nla_total_size(4) /* RTA_PREFSRC */
 468                          + nla_total_size(TCP_CA_NAME_MAX); /* RTAX_CC_ALGO */
 469         unsigned int nhs = fib_info_num_path(fi);
 470
 471         /* space for nested metrics */
 472         payload += nla_total_size((RTAX_MAX * nla_total_size(4)));
 473
 474         if (fi->nh)
 475                 payload += nla_total_size(4); /* RTA_NH_ID */
 476
 477         if (nhs) {
 478                 size_t nh_encapsize = 0;
 479                 /* Also handles the special case nhs == 1 */
 480
 481                 /* each nexthop is packed in an attribute */
 482                 size_t nhsize = nla_total_size(sizeof(struct rtnexthop));
 483                 unsigned int i;
 484
 485                 /* may contain flow and gateway attribute */
 486                 nhsize += 2 * nla_total_size(4);
 487
 488                 /* grab encap info */
 489                 for (i = 0; i < fib_info_num_path(fi); i++) {
 490                         struct fib_nh_common *nhc = fib_info_nhc(fi, i);
 491
 492                         if (nhc->nhc_lwtstate) {
 493                                 /* RTA_ENCAP_TYPE */
 494                                 nh_encapsize += lwtunnel_get_encap_size(
 495                                                 nhc->nhc_lwtstate);
 496                                 /* RTA_ENCAP */
 497                                 nh_encapsize +=  nla_total_size(2);
 498                         }
 499                 }
 500
 501                 /* all nexthops are packed in a nested attribute */
 502                 payload += nla_total_size((nhs * nhsize) + nh_encapsize);
 503
 504         }
 505
 506         return payload;
 507 }
 508
 509 void rtmsg_fib(int event, __be32 key, struct fib_alias *fa,
 510                int dst_len, u32 tb_id, const struct nl_info *info,
 511                unsigned int nlm_flags)
 512 {
 513         struct fib_rt_info fri;
 514         struct sk_buff *skb;
 515         u32 seq = info->nlh ? info->nlh->nlmsg_seq : 0;
 516         int err = -ENOBUFS;
 517
 518         skb = nlmsg_new(fib_nlmsg_size(fa->fa_info), GFP_KERNEL);
 519         if (!skb)
 520                 goto errout;
 521
 522         fri.fi = fa->fa_info;
 523         fri.tb_id = tb_id;
 524         fri.dst = key;
 525         fri.dst_len = dst_len;
 526         fri.tos = fa->fa_tos;
 527         fri.type = fa->fa_type;
 528         fri.offload = READ_ONCE(fa->offload);
 529         fri.trap = READ_ONCE(fa->trap);
 530         fri.offload_failed = READ_ONCE(fa->offload_failed);
 531         err = fib_dump_info(skb, info->portid, seq, event, &fri, nlm_flags);
 532         if (err < 0) {
 533                 /* -EMSGSIZE implies BUG in fib_nlmsg_size() */
 534                 WARN_ON(err == -EMSGSIZE);
 535                 kfree_skb(skb);
 536                 goto errout;
 537         }
 538         rtnl_notify(skb, info->nl_net, info->portid, RTNLGRP_IPV4_ROUTE,
 539                     info->nlh, GFP_KERNEL);
 540         return;
 541 errout:
 542         if (err < 0)
 543                 rtnl_set_sk_err(info->nl_net, RTNLGRP_IPV4_ROUTE, err);
 544 }
 545
 546 static int fib_detect_death(struct fib_info *fi, int order,
 547                             struct fib_info **last_resort, int *last_idx,
 548                             int dflt)
 549 {
 550         const struct fib_nh_common *nhc = fib_info_nhc(fi, 0);
 551         struct neighbour *n;
 552         int state = NUD_NONE;
 553
 554         if (likely(nhc->nhc_gw_family == AF_INET))
 555                 n = neigh_lookup(&arp_tbl, &nhc->nhc_gw.ipv4, nhc->nhc_dev);
 556         else if (nhc->nhc_gw_family == AF_INET6)
 557                 n = neigh_lookup(ipv6_stub->nd_tbl, &nhc->nhc_gw.ipv6,
 558                                  nhc->nhc_dev);
 559         else
 560                 n = NULL;
 561
 562         if (n) {
 563                 state = n->nud_state;
 564                 neigh_release(n);
 565         } else {
 566                 return 0;
 567         }
 568         if (state == NUD_REACHABLE)
 569                 return 0;
 570         if ((state & NUD_VALID) && order != dflt)
 571                 return 0;
 572         if ((state & NUD_VALID) ||
 573             (*last_idx < 0 && order > dflt && state != NUD_INCOMPLETE)) {
 574                 *last_resort = fi;
 575                 *last_idx = order;
 576         }
 577         return 1;
 578 }
 579
 580 int fib_nh_common_init(struct net *net, struct fib_nh_common *nhc,
 581                        struct nlattr *encap, u16 encap_type,
 582                        void *cfg, gfp_t gfp_flags,
 583                        struct netlink_ext_ack *extack)
 584 {
 585         int err;
 586
 587         nhc->nhc_pcpu_rth_output = alloc_percpu_gfp(struct rtable __rcu *,
 588                                                     gfp_flags);
 589         if (!nhc->nhc_pcpu_rth_output)
 590                 return -ENOMEM;
 591
 592         if (encap) {
 593                 struct lwtunnel_state *lwtstate;
 594
 595                 if (encap_type == LWTUNNEL_ENCAP_NONE) {
 596                         NL_SET_ERR_MSG(extack, "LWT encap type not specified");
 597                         err = -EINVAL;
 598                         goto lwt_failure;
 599                 }
 600                 err = lwtunnel_build_state(net, encap_type, encap,
 601                                            nhc->nhc_family, cfg, &lwtstate,
 602                                            extack);
 603                 if (err)
 604                         goto lwt_failure;
 605
 606                 nhc->nhc_lwtstate = lwtstate_get(lwtstate);
 607         }
 608
 609         return 0;
 610
 611 lwt_failure:
 612         rt_fibinfo_free_cpus(nhc->nhc_pcpu_rth_output);
 613         nhc->nhc_pcpu_rth_output = NULL;
 614         return err;
 615 }
 616 EXPORT_SYMBOL_GPL(fib_nh_common_init);
 617
 618 int fib_nh_init(struct net *net, struct fib_nh *nh,
 619                 struct fib_config *cfg, int nh_weight,
 620                 struct netlink_ext_ack *extack)
 621 {
 622         int err;
 623
 624         nh->fib_nh_family = AF_INET;
 625
 626         err = fib_nh_common_init(net, &nh->nh_common, cfg->fc_encap,
 627                                  cfg->fc_encap_type, cfg, GFP_KERNEL, extack);
 628         if (err)
 629                 return err;
 630
 631         nh->fib_nh_oif = cfg->fc_oif;
 632         nh->fib_nh_gw_family = cfg->fc_gw_family;
 633         if (cfg->fc_gw_family == AF_INET)
 634                 nh->fib_nh_gw4 = cfg->fc_gw4;
 635         else if (cfg->fc_gw_family == AF_INET6)
 636                 nh->fib_nh_gw6 = cfg->fc_gw6;
 637
 638         nh->fib_nh_flags = cfg->fc_flags;
 639
 640 #ifdef CONFIG_IP_ROUTE_CLASSID
 641         nh->nh_tclassid = cfg->fc_flow;
 642         if (nh->nh_tclassid)
 643                 atomic_inc(&net->ipv4.fib_num_tclassid_users);
 644 #endif
 645 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 646         nh->fib_nh_weight = nh_weight;
 647 #endif
 648         return 0;
 649 }
 650
 651 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 652
 653 static int fib_count_nexthops(struct rtnexthop *rtnh, int remaining,
 654                               struct netlink_ext_ack *extack)
 655 {
 656         int nhs = 0;
 657
 658         while (rtnh_ok(rtnh, remaining)) {
 659                 nhs++;
 660                 rtnh = rtnh_next(rtnh, &remaining);
 661         }
 662
 663         /* leftover implies invalid nexthop configuration, discard it */
 664         if (remaining > 0) {
 665                 NL_SET_ERR_MSG(extack,
 666                                "Invalid nexthop configuration - extra data after nexthops");
 667                 nhs = 0;
 668         }
 669
 670         return nhs;
 671 }
 672
 673 static int fib_gw_from_attr(__be32 *gw, struct nlattr *nla,
 674                             struct netlink_ext_ack *extack)
 675 {
 676         if (nla_len(nla) < sizeof(*gw)) {
 677                 NL_SET_ERR_MSG(extack, "Invalid IPv4 address in RTA_GATEWAY");
 678                 return -EINVAL;
 679         }
 680
 681         *gw = nla_get_in_addr(nla);
 682
 683         return 0;
 684 }
 685
 686 /* only called when fib_nh is integrated into fib_info */
 687 static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh,
 688                        int remaining, struct fib_config *cfg,
 689                        struct netlink_ext_ack *extack)
 690 {
 691         struct net *net = fi->fib_net;
 692         struct fib_config fib_cfg;
 693         struct fib_nh *nh;
 694         int ret;
 695
 696         change_nexthops(fi) {
 697                 int attrlen;
 698
 699                 memset(&fib_cfg, 0, sizeof(fib_cfg));
 700
 701                 if (!rtnh_ok(rtnh, remaining)) {
 702                         NL_SET_ERR_MSG(extack,
 703                                        "Invalid nexthop configuration - extra data after nexthop");
 704                         return -EINVAL;
 705                 }
 706
 707                 if (rtnh->rtnh_flags & (RTNH_F_DEAD | RTNH_F_LINKDOWN)) {
 708                         NL_SET_ERR_MSG(extack,
 709                                        "Invalid flags for nexthop - can not contain DEAD or LINKDOWN");
 710                         return -EINVAL;
 711                 }
 712
 713                 fib_cfg.fc_flags = (cfg->fc_flags & ~0xFF) | rtnh->rtnh_flags;
 714                 fib_cfg.fc_oif = rtnh->rtnh_ifindex;
 715
 716                 attrlen = rtnh_attrlen(rtnh);
 717                 if (attrlen > 0) {
 718                         struct nlattr *nla, *nlav, *attrs = rtnh_attrs(rtnh);
 719
 720                         nla = nla_find(attrs, attrlen, RTA_GATEWAY);
 721                         nlav = nla_find(attrs, attrlen, RTA_VIA);
 722                         if (nla && nlav) {
 723                                 NL_SET_ERR_MSG(extack,
 724                                                "Nexthop configuration can not contain both GATEWAY and VIA");
 725                                 return -EINVAL;
 726                         }
 727                         if (nla) {
 728                                 ret = fib_gw_from_attr(&fib_cfg.fc_gw4, nla,
 729                                                        extack);
 730                                 if (ret)
 731                                         goto errout;
 732
 733                                 if (fib_cfg.fc_gw4)
 734                                         fib_cfg.fc_gw_family = AF_INET;
 735                         } else if (nlav) {
 736                                 ret = fib_gw_from_via(&fib_cfg, nlav, extack);
 737                                 if (ret)
 738                                         goto errout;
 739                         }
 740
 741                         nla = nla_find(attrs, attrlen, RTA_FLOW);
 742                         if (nla) {
 743                                 if (nla_len(nla) < sizeof(u32)) {
 744                                         NL_SET_ERR_MSG(extack, "Invalid RTA_FLOW");
 745                                         return -EINVAL;
 746                                 }
 747                                 fib_cfg.fc_flow = nla_get_u32(nla);
 748                         }
 749
 750                         fib_cfg.fc_encap = nla_find(attrs, attrlen, RTA_ENCAP);
 751                         /* RTA_ENCAP_TYPE length checked in
 752                          * lwtunnel_valid_encap_type_attr
 753                          */
 754                         nla = nla_find(attrs, attrlen, RTA_ENCAP_TYPE);
 755                         if (nla)
 756                                 fib_cfg.fc_encap_type = nla_get_u16(nla);
 757                 }
 758
 759                 ret = fib_nh_init(net, nexthop_nh, &fib_cfg,
 760                                   rtnh->rtnh_hops + 1, extack);
 761                 if (ret)
 762                         goto errout;
 763
 764                 rtnh = rtnh_next(rtnh, &remaining);
 765         } endfor_nexthops(fi);
 766
 767         ret = -EINVAL;
 768         nh = fib_info_nh(fi, 0);
 769         if (cfg->fc_oif && nh->fib_nh_oif != cfg->fc_oif) {
 770                 NL_SET_ERR_MSG(extack,
 771                                "Nexthop device index does not match RTA_OIF");
 772                 goto errout;
 773         }
 774         if (cfg->fc_gw_family) {
 775                 if (cfg->fc_gw_family != nh->fib_nh_gw_family ||
 776                     (cfg->fc_gw_family == AF_INET &&
 777                      nh->fib_nh_gw4 != cfg->fc_gw4) ||
 778                     (cfg->fc_gw_family == AF_INET6 &&
 779                      ipv6_addr_cmp(&nh->fib_nh_gw6, &cfg->fc_gw6))) {
 780                         NL_SET_ERR_MSG(extack,
 781                                        "Nexthop gateway does not match RTA_GATEWAY or RTA_VIA");
 782                         goto errout;
 783                 }
 784         }
 785 #ifdef CONFIG_IP_ROUTE_CLASSID
 786         if (cfg->fc_flow && nh->nh_tclassid != cfg->fc_flow) {
 787                 NL_SET_ERR_MSG(extack,
 788                                "Nexthop class id does not match RTA_FLOW");
 789                 goto errout;
 790         }
 791 #endif
 792         ret = 0;
 793 errout:
 794         return ret;
 795 }
 796
 797 /* only called when fib_nh is integrated into fib_info */
 798 static void fib_rebalance(struct fib_info *fi)
 799 {
 800         int total;
 801         int w;
 802
 803         if (fib_info_num_path(fi) < 2)
 804                 return;
 805
 806         total = 0;
 807         for_nexthops(fi) {
 808                 if (nh->fib_nh_flags & RTNH_F_DEAD)
 809                         continue;
 810
 811                 if (ip_ignore_linkdown(nh->fib_nh_dev) &&
 812                     nh->fib_nh_flags & RTNH_F_LINKDOWN)
 813                         continue;
 814
 815                 total += nh->fib_nh_weight;
 816         } endfor_nexthops(fi);
 817
 818         w = 0;
 819         change_nexthops(fi) {
 820                 int upper_bound;
 821
 822                 if (nexthop_nh->fib_nh_flags & RTNH_F_DEAD) {
 823                         upper_bound = -1;
 824                 } else if (ip_ignore_linkdown(nexthop_nh->fib_nh_dev) &&
 825                            nexthop_nh->fib_nh_flags & RTNH_F_LINKDOWN) {
 826                         upper_bound = -1;
 827                 } else {
 828                         w += nexthop_nh->fib_nh_weight;
 829                         upper_bound = DIV_ROUND_CLOSEST_ULL((u64)w << 31,
 830                                                             total) - 1;
 831                 }
 832
 833                 atomic_set(&nexthop_nh->fib_nh_upper_bound, upper_bound);
 834         } endfor_nexthops(fi);
 835 }
 836 #else /* CONFIG_IP_ROUTE_MULTIPATH */
 837
 838 static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh,
 839                        int remaining, struct fib_config *cfg,
 840                        struct netlink_ext_ack *extack)
 841 {
 842         NL_SET_ERR_MSG(extack, "Multipath support not enabled in kernel");
 843
 844         return -EINVAL;
 845 }
 846
 847 #define fib_rebalance(fi) do { } while (0)
 848
 849 #endif /* CONFIG_IP_ROUTE_MULTIPATH */
 850
 851 static int fib_encap_match(struct net *net, u16 encap_type,
 852                            struct nlattr *encap,
 853                            const struct fib_nh *nh,
 854                            const struct fib_config *cfg,
 855                            struct netlink_ext_ack *extack)
 856 {
 857         struct lwtunnel_state *lwtstate;
 858         int ret, result = 0;
 859
 860         if (encap_type == LWTUNNEL_ENCAP_NONE)
 861                 return 0;
 862
 863         ret = lwtunnel_build_state(net, encap_type, encap, AF_INET,
 864                                    cfg, &lwtstate, extack);
 865         if (!ret) {
 866                 result = lwtunnel_cmp_encap(lwtstate, nh->fib_nh_lws);
 867                 lwtstate_free(lwtstate);
 868         }
 869
 870         return result;
 871 }
 872
 873 int fib_nh_match(struct net *net, struct fib_config *cfg, struct fib_info *fi,
 874                  struct netlink_ext_ack *extack)
 875 {
 876 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 877         struct rtnexthop *rtnh;
 878         int remaining;
 879 #endif
 880
 881         if (cfg->fc_priority && cfg->fc_priority != fi->fib_priority)
 882                 return 1;
 883
 884         if (cfg->fc_nh_id) {
 885                 if (fi->nh && cfg->fc_nh_id == fi->nh->id)
 886                         return 0;
 887                 return 1;
 888         }
 889
 890         if (cfg->fc_oif || cfg->fc_gw_family) {
 891                 struct fib_nh *nh = fib_info_nh(fi, 0);
 892
 893                 if (cfg->fc_encap) {
 894                         if (fib_encap_match(net, cfg->fc_encap_type,
 895                                             cfg->fc_encap, nh, cfg, extack))
 896                                 return 1;
 897                 }
 898 #ifdef CONFIG_IP_ROUTE_CLASSID
 899                 if (cfg->fc_flow &&
 900                     cfg->fc_flow != nh->nh_tclassid)
 901                         return 1;
 902 #endif
 903                 if ((cfg->fc_oif && cfg->fc_oif != nh->fib_nh_oif) ||
 904                     (cfg->fc_gw_family &&
 905                      cfg->fc_gw_family != nh->fib_nh_gw_family))
 906                         return 1;
 907
 908                 if (cfg->fc_gw_family == AF_INET &&
 909                     cfg->fc_gw4 != nh->fib_nh_gw4)
 910                         return 1;
 911
 912                 if (cfg->fc_gw_family == AF_INET6 &&
 913                     ipv6_addr_cmp(&cfg->fc_gw6, &nh->fib_nh_gw6))
 914                         return 1;
 915
 916                 return 0;
 917         }
 918
 919 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 920         if (!cfg->fc_mp)
 921                 return 0;
 922
 923         rtnh = cfg->fc_mp;
 924         remaining = cfg->fc_mp_len;
 925
 926         for_nexthops(fi) {
 927                 int attrlen;
 928
 929                 if (!rtnh_ok(rtnh, remaining))
 930                         return -EINVAL;
 931
 932                 if (rtnh->rtnh_ifindex && rtnh->rtnh_ifindex != nh->fib_nh_oif)
 933                         return 1;
 934
 935                 attrlen = rtnh_attrlen(rtnh);
 936                 if (attrlen > 0) {
 937                         struct nlattr *nla, *nlav, *attrs = rtnh_attrs(rtnh);
 938                         int err;
 939
 940                         nla = nla_find(attrs, attrlen, RTA_GATEWAY);
 941                         nlav = nla_find(attrs, attrlen, RTA_VIA);
 942                         if (nla && nlav) {
 943                                 NL_SET_ERR_MSG(extack,
 944                                                "Nexthop configuration can not contain both GATEWAY and VIA");
 945                                 return -EINVAL;
 946                         }
 947
 948                         if (nla) {
 949                                 __be32 gw;
 950
 951                                 err = fib_gw_from_attr(&gw, nla, extack);
 952                                 if (err)
 953                                         return err;
 954
 955                                 if (nh->fib_nh_gw_family != AF_INET ||
 956                                     gw != nh->fib_nh_gw4)
 957                                         return 1;
 958                         } else if (nlav) {
 959                                 struct fib_config cfg2;
 960
 961                                 err = fib_gw_from_via(&cfg2, nlav, extack);
 962                                 if (err)
 963                                         return err;
 964
 965                                 switch (nh->fib_nh_gw_family) {
 966                                 case AF_INET:
 967                                         if (cfg2.fc_gw_family != AF_INET ||
 968                                             cfg2.fc_gw4 != nh->fib_nh_gw4)
 969                                                 return 1;
 970                                         break;
 971                                 case AF_INET6:
 972                                         if (cfg2.fc_gw_family != AF_INET6 ||
 973                                             ipv6_addr_cmp(&cfg2.fc_gw6,
 974                                                           &nh->fib_nh_gw6))
 975                                                 return 1;
 976                                         break;
 977                                 }
 978                         }
 979
 980 #ifdef CONFIG_IP_ROUTE_CLASSID
 981                         nla = nla_find(attrs, attrlen, RTA_FLOW);
 982                         if (nla) {
 983                                 if (nla_len(nla) < sizeof(u32)) {
 984                                         NL_SET_ERR_MSG(extack, "Invalid RTA_FLOW");
 985                                         return -EINVAL;
 986                                 }
 987                                 if (nla_get_u32(nla) != nh->nh_tclassid)
 988                                         return 1;
 989                         }
 990 #endif
 991                 }
 992
 993                 rtnh = rtnh_next(rtnh, &remaining);
 994         } endfor_nexthops(fi);
 995 #endif
 996         return 0;
 997 }
 998
 999 bool fib_metrics_match(struct fib_config *cfg, struct fib_info *fi)
1000 {
1001         struct nlattr *nla;
1002         int remaining;
1003
1004         if (!cfg->fc_mx)
1005                 return true;
1006
1007         nla_for_each_attr(nla, cfg->fc_mx, cfg->fc_mx_len, remaining) {
1008                 int type = nla_type(nla);
1009                 u32 fi_val, val;
1010
1011                 if (!type)
1012                         continue;
1013                 if (type > RTAX_MAX)
1014                         return false;
1015
1016                 if (type == RTAX_CC_ALGO) {
1017                         char tmp[TCP_CA_NAME_MAX];
1018                         bool ecn_ca = false;
1019
1020                         nla_strscpy(tmp, nla, sizeof(tmp));
1021                         val = tcp_ca_get_key_by_name(fi->fib_net, tmp, &ecn_ca);
1022                 } else {
1023                         if (nla_len(nla) != sizeof(u32))
1024                                 return false;
1025                         val = nla_get_u32(nla);
1026                 }
1027
1028                 fi_val = fi->fib_metrics->metrics[type - 1];
1029                 if (type == RTAX_FEATURES)
1030                         fi_val &= ~DST_FEATURE_ECN_CA;
1031
1032                 if (fi_val != val)
1033                         return false;
1034         }
1035
1036         return true;
1037 }
1038
1039 static int fib_check_nh_v6_gw(struct net *net, struct fib_nh *nh,
1040                               u32 table, struct netlink_ext_ack *extack)
1041 {
1042         struct fib6_config cfg = {
1043                 .fc_table = table,
1044                 .fc_flags = nh->fib_nh_flags | RTF_GATEWAY,
1045                 .fc_ifindex = nh->fib_nh_oif,
1046                 .fc_gateway = nh->fib_nh_gw6,
1047         };
1048         struct fib6_nh fib6_nh = {};
1049         int err;
1050
1051         err = ipv6_stub->fib6_nh_init(net, &fib6_nh, &cfg, GFP_KERNEL, extack);
1052         if (!err) {
1053                 nh->fib_nh_dev = fib6_nh.fib_nh_dev;
1054                 dev_hold_track(nh->fib_nh_dev, &nh->fib_nh_dev_tracker, GFP_KERNEL);
1055                 nh->fib_nh_oif = nh->fib_nh_dev->ifindex;
1056                 nh->fib_nh_scope = RT_SCOPE_LINK;
1057
1058                 ipv6_stub->fib6_nh_release(&fib6_nh);
1059         }
1060
1061         return err;
1062 }
1063
1064 /*
1065  * Picture
1066  * -------
1067  *
1068  * Semantics of nexthop is very messy by historical reasons.
1069  * We have to take into account, that:
1070  * a) gateway can be actually local interface address,
1071  *    so that gatewayed route is direct.
1072  * b) gateway must be on-link address, possibly
1073  *    described not by an ifaddr, but also by a direct route.
1074  * c) If both gateway and interface are specified, they should not
1075  *    contradict.
1076  * d) If we use tunnel routes, gateway could be not on-link.
1077  *
1078  * Attempt to reconcile all of these (alas, self-contradictory) conditions
1079  * results in pretty ugly and hairy code with obscure logic.
1080  *
1081  * I chose to generalized it instead, so that the size
1082  * of code does not increase practically, but it becomes
1083  * much more general.
1084  * Every prefix is assigned a "scope" value: "host" is local address,
1085  * "link" is direct route,
1086  * [ ... "site" ... "interior" ... ]
1087  * and "universe" is true gateway route with global meaning.
1088  *
1089  * Every prefix refers to a set of "nexthop"s (gw, oif),
1090  * where gw must have narrower scope. This recursion stops
1091  * when gw has LOCAL scope or if "nexthop" is declared ONLINK,
1092  * which means that gw is forced to be on link.
1093  *
1094  * Code is still hairy, but now it is apparently logically
1095  * consistent and very flexible. F.e. as by-product it allows
1096  * to co-exists in peace independent exterior and interior
1097  * routing processes.
1098  *
1099  * Normally it looks as following.
1100  *
1101  * {universe prefix}  -> (gw, oif) [scope link]
1102  *                |
1103  *                |-> {link prefix} -> (gw, oif) [scope local]
1104  *                                      |
1105  *                                      |-> {local prefix} (terminal node)
1106  */
1107 static int fib_check_nh_v4_gw(struct net *net, struct fib_nh *nh, u32 table,
1108                               u8 scope, struct netlink_ext_ack *extack)
1109 {
1110         struct net_device *dev;
1111         struct fib_result res;
1112         int err = 0;
1113
1114         if (nh->fib_nh_flags & RTNH_F_ONLINK) {
1115                 unsigned int addr_type;
1116
1117                 if (scope >= RT_SCOPE_LINK) {
1118                         NL_SET_ERR_MSG(extack, "Nexthop has invalid scope");
1119                         return -EINVAL;
1120                 }
1121                 dev = __dev_get_by_index(net, nh->fib_nh_oif);
1122                 if (!dev) {
1123                         NL_SET_ERR_MSG(extack, "Nexthop device required for onlink");
1124                         return -ENODEV;
1125                 }
1126                 if (!(dev->flags & IFF_UP)) {
1127                         NL_SET_ERR_MSG(extack, "Nexthop device is not up");
1128                         return -ENETDOWN;
1129                 }
1130                 addr_type = inet_addr_type_dev_table(net, dev, nh->fib_nh_gw4);
1131                 if (addr_type != RTN_UNICAST) {
1132                         NL_SET_ERR_MSG(extack, "Nexthop has invalid gateway");
1133                         return -EINVAL;
1134                 }
1135                 if (!netif_carrier_ok(dev))
1136                         nh->fib_nh_flags |= RTNH_F_LINKDOWN;
1137                 nh->fib_nh_dev = dev;
1138                 dev_hold_track(dev, &nh->fib_nh_dev_tracker, GFP_ATOMIC);
1139                 nh->fib_nh_scope = RT_SCOPE_LINK;
1140                 return 0;
1141         }
1142         rcu_read_lock();
1143         {
1144                 struct fib_table *tbl = NULL;
1145                 struct flowi4 fl4 = {
1146                         .daddr = nh->fib_nh_gw4,
1147                         .flowi4_scope = scope + 1,
1148                         .flowi4_oif = nh->fib_nh_oif,
1149                         .flowi4_iif = LOOPBACK_IFINDEX,
1150                 };
1151
1152                 /* It is not necessary, but requires a bit of thinking */
1153                 if (fl4.flowi4_scope < RT_SCOPE_LINK)
1154                         fl4.flowi4_scope = RT_SCOPE_LINK;
1155
1156                 if (table && table != RT_TABLE_MAIN)
1157                         tbl = fib_get_table(net, table);
1158
1159                 if (tbl)
1160                         err = fib_table_lookup(tbl, &fl4, &res,
1161                                                FIB_LOOKUP_IGNORE_LINKSTATE |
1162                                                FIB_LOOKUP_NOREF);
1163
1164                 /* on error or if no table given do full lookup. This
1165                  * is needed for example when nexthops are in the local
1166                  * table rather than the given table
1167                  */
1168                 if (!tbl || err) {
1169                         err = fib_lookup(net, &fl4, &res,
1170                                          FIB_LOOKUP_IGNORE_LINKSTATE);
1171                 }
1172
1173                 if (err) {
1174                         NL_SET_ERR_MSG(extack, "Nexthop has invalid gateway");
1175                         goto out;
1176                 }
1177         }
1178
1179         err = -EINVAL;
1180         if (res.type != RTN_UNICAST && res.type != RTN_LOCAL) {
1181                 NL_SET_ERR_MSG(extack, "Nexthop has invalid gateway");
1182                 goto out;
1183         }
1184         nh->fib_nh_scope = res.scope;
1185         nh->fib_nh_oif = FIB_RES_OIF(res);
1186         nh->fib_nh_dev = dev = FIB_RES_DEV(res);
1187         if (!dev) {
1188                 NL_SET_ERR_MSG(extack,
1189                                "No egress device for nexthop gateway");
1190                 goto out;
1191         }
1192         dev_hold_track(dev, &nh->fib_nh_dev_tracker, GFP_ATOMIC);
1193         if (!netif_carrier_ok(dev))
1194                 nh->fib_nh_flags |= RTNH_F_LINKDOWN;
1195         err = (dev->flags & IFF_UP) ? 0 : -ENETDOWN;
1196 out:
1197         rcu_read_unlock();
1198         return err;
1199 }
1200
1201 static int fib_check_nh_nongw(struct net *net, struct fib_nh *nh,
1202                               struct netlink_ext_ack *extack)
1203 {
1204         struct in_device *in_dev;
1205         int err;
1206
1207         if (nh->fib_nh_flags & (RTNH_F_PERVASIVE | RTNH_F_ONLINK)) {
1208                 NL_SET_ERR_MSG(extack,
1209                                "Invalid flags for nexthop - PERVASIVE and ONLINK can not be set");
1210                 return -EINVAL;
1211         }
1212
1213         rcu_read_lock();
1214
1215         err = -ENODEV;
1216         in_dev = inetdev_by_index(net, nh->fib_nh_oif);
1217         if (!in_dev)
1218                 goto out;
1219         err = -ENETDOWN;
1220         if (!(in_dev->dev->flags & IFF_UP)) {
1221                 NL_SET_ERR_MSG(extack, "Device for nexthop is not up");
1222                 goto out;
1223         }
1224
1225         nh->fib_nh_dev = in_dev->dev;
1226         dev_hold_track(nh->fib_nh_dev, &nh->fib_nh_dev_tracker, GFP_ATOMIC);
1227         nh->fib_nh_scope = RT_SCOPE_HOST;
1228         if (!netif_carrier_ok(nh->fib_nh_dev))
1229                 nh->fib_nh_flags |= RTNH_F_LINKDOWN;
1230         err = 0;
1231 out:
1232         rcu_read_unlock();
1233         return err;
1234 }
1235
1236 int fib_check_nh(struct net *net, struct fib_nh *nh, u32 table, u8 scope,
1237                  struct netlink_ext_ack *extack)
1238 {
1239         int err;
1240
1241         if (nh->fib_nh_gw_family == AF_INET)
1242                 err = fib_check_nh_v4_gw(net, nh, table, scope, extack);
1243         else if (nh->fib_nh_gw_family == AF_INET6)
1244                 err = fib_check_nh_v6_gw(net, nh, table, extack);
1245         else
1246                 err = fib_check_nh_nongw(net, nh, extack);
1247
1248         return err;
1249 }
1250
1251 static struct hlist_head *
1252 fib_info_laddrhash_bucket(const struct net *net, __be32 val)
1253 {
1254         u32 slot = hash_32(net_hash_mix(net) ^ (__force u32)val,
1255                            fib_info_hash_bits);
1256
1257         return &fib_info_laddrhash[slot];
1258 }
1259
1260 static struct hlist_head *fib_info_hash_alloc(int bytes)
1261 {
1262         if (bytes <= PAGE_SIZE)
1263                 return kzalloc(bytes, GFP_KERNEL);
1264         else
1265                 return (struct hlist_head *)
1266                         __get_free_pages(GFP_KERNEL | __GFP_ZERO,
1267                                          get_order(bytes));
1268 }
1269
1270 static void fib_info_hash_free(struct hlist_head *hash, int bytes)
1271 {
1272         if (!hash)
1273                 return;
1274
1275         if (bytes <= PAGE_SIZE)
1276                 kfree(hash);
1277         else
1278                 free_pages((unsigned long) hash, get_order(bytes));
1279 }
1280
1281 static void fib_info_hash_move(struct hlist_head *new_info_hash,
1282                                struct hlist_head *new_laddrhash,
1283                                unsigned int new_size)
1284 {
1285         struct hlist_head *old_info_hash, *old_laddrhash;
1286         unsigned int old_size = fib_info_hash_size;
1287         unsigned int i, bytes;
1288
1289         spin_lock_bh(&fib_info_lock);
1290         old_info_hash = fib_info_hash;
1291         old_laddrhash = fib_info_laddrhash;
1292         fib_info_hash_size = new_size;
1293         fib_info_hash_bits = ilog2(new_size);
1294
1295         for (i = 0; i < old_size; i++) {
1296                 struct hlist_head *head = &fib_info_hash[i];
1297                 struct hlist_node *n;
1298                 struct fib_info *fi;
1299
1300                 hlist_for_each_entry_safe(fi, n, head, fib_hash) {
1301                         struct hlist_head *dest;
1302                         unsigned int new_hash;
1303
1304                         new_hash = fib_info_hashfn(fi);
1305                         dest = &new_info_hash[new_hash];
1306                         hlist_add_head(&fi->fib_hash, dest);
1307                 }
1308         }
1309         fib_info_hash = new_info_hash;
1310
1311         fib_info_laddrhash = new_laddrhash;
1312         for (i = 0; i < old_size; i++) {
1313                 struct hlist_head *lhead = &old_laddrhash[i];
1314                 struct hlist_node *n;
1315                 struct fib_info *fi;
1316
1317                 hlist_for_each_entry_safe(fi, n, lhead, fib_lhash) {
1318                         struct hlist_head *ldest;
1319
1320                         ldest = fib_info_laddrhash_bucket(fi->fib_net,
1321                                                           fi->fib_prefsrc);
1322                         hlist_add_head(&fi->fib_lhash, ldest);
1323                 }
1324         }
1325
1326         spin_unlock_bh(&fib_info_lock);
1327
1328         bytes = old_size * sizeof(struct hlist_head *);
1329         fib_info_hash_free(old_info_hash, bytes);
1330         fib_info_hash_free(old_laddrhash, bytes);
1331 }
1332
1333 __be32 fib_info_update_nhc_saddr(struct net *net, struct fib_nh_common *nhc,
1334                                  unsigned char scope)
1335 {
1336         struct fib_nh *nh;
1337
1338         if (nhc->nhc_family != AF_INET)
1339                 return inet_select_addr(nhc->nhc_dev, 0, scope);
1340
1341         nh = container_of(nhc, struct fib_nh, nh_common);
1342         nh->nh_saddr = inet_select_addr(nh->fib_nh_dev, nh->fib_nh_gw4, scope);
1343         nh->nh_saddr_genid = atomic_read(&net->ipv4.dev_addr_genid);
1344
1345         return nh->nh_saddr;
1346 }
1347
1348 __be32 fib_result_prefsrc(struct net *net, struct fib_result *res)
1349 {
1350         struct fib_nh_common *nhc = res->nhc;
1351
1352         if (res->fi->fib_prefsrc)
1353                 return res->fi->fib_prefsrc;
1354
1355         if (nhc->nhc_family == AF_INET) {
1356                 struct fib_nh *nh;
1357
1358                 nh = container_of(nhc, struct fib_nh, nh_common);
1359                 if (nh->nh_saddr_genid == atomic_read(&net->ipv4.dev_addr_genid))
1360                         return nh->nh_saddr;
1361         }
1362
1363         return fib_info_update_nhc_saddr(net, nhc, res->fi->fib_scope);
1364 }
1365
1366 static bool fib_valid_prefsrc(struct fib_config *cfg, __be32 fib_prefsrc)
1367 {
1368         if (cfg->fc_type != RTN_LOCAL || !cfg->fc_dst ||
1369             fib_prefsrc != cfg->fc_dst) {
1370                 u32 tb_id = cfg->fc_table;
1371                 int rc;
1372
1373                 if (tb_id == RT_TABLE_MAIN)
1374                         tb_id = RT_TABLE_LOCAL;
1375
1376                 rc = inet_addr_type_table(cfg->fc_nlinfo.nl_net,
1377                                           fib_prefsrc, tb_id);
1378
1379                 if (rc != RTN_LOCAL && tb_id != RT_TABLE_LOCAL) {
1380                         rc = inet_addr_type_table(cfg->fc_nlinfo.nl_net,
1381                                                   fib_prefsrc, RT_TABLE_LOCAL);
1382                 }
1383
1384                 if (rc != RTN_LOCAL)
1385                         return false;
1386         }
1387         return true;
1388 }
1389
1390 struct fib_info *fib_create_info(struct fib_config *cfg,
1391                                  struct netlink_ext_ack *extack)
1392 {
1393         int err;
1394         struct fib_info *fi = NULL;
1395         struct nexthop *nh = NULL;
1396         struct fib_info *ofi;
1397         int nhs = 1;
1398         struct net *net = cfg->fc_nlinfo.nl_net;
1399
1400         if (cfg->fc_type > RTN_MAX)
1401                 goto err_inval;
1402
1403         /* Fast check to catch the most weird cases */
1404         if (fib_props[cfg->fc_type].scope > cfg->fc_scope) {
1405                 NL_SET_ERR_MSG(extack, "Invalid scope");
1406                 goto err_inval;
1407         }
1408
1409         if (cfg->fc_flags & (RTNH_F_DEAD | RTNH_F_LINKDOWN)) {
1410                 NL_SET_ERR_MSG(extack,
1411                                "Invalid rtm_flags - can not contain DEAD or LINKDOWN");
1412                 goto err_inval;
1413         }
1414
1415         if (cfg->fc_nh_id) {
1416                 if (!cfg->fc_mx) {
1417                         fi = fib_find_info_nh(net, cfg);
1418                         if (fi) {
1419                                 refcount_inc(&fi->fib_treeref);
1420                                 return fi;
1421                         }
1422                 }
1423
1424                 nh = nexthop_find_by_id(net, cfg->fc_nh_id);
1425                 if (!nh) {
1426                         NL_SET_ERR_MSG(extack, "Nexthop id does not exist");
1427                         goto err_inval;
1428                 }
1429                 nhs = 0;
1430         }
1431
1432 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1433         if (cfg->fc_mp) {
1434                 nhs = fib_count_nexthops(cfg->fc_mp, cfg->fc_mp_len, extack);
1435                 if (nhs == 0)
1436                         goto err_inval;
1437         }
1438 #endif
1439
1440         err = -ENOBUFS;
1441
1442         /* Paired with WRITE_ONCE() in fib_release_info() */
1443         if (READ_ONCE(fib_info_cnt) >= fib_info_hash_size) {
1444                 unsigned int new_size = fib_info_hash_size << 1;
1445                 struct hlist_head *new_info_hash;
1446                 struct hlist_head *new_laddrhash;
1447                 unsigned int bytes;
1448
1449                 if (!new_size)
1450                         new_size = 16;
1451                 bytes = new_size * sizeof(struct hlist_head *);
1452                 new_info_hash = fib_info_hash_alloc(bytes);
1453                 new_laddrhash = fib_info_hash_alloc(bytes);
1454                 if (!new_info_hash || !new_laddrhash) {
1455                         fib_info_hash_free(new_info_hash, bytes);
1456                         fib_info_hash_free(new_laddrhash, bytes);
1457                 } else
1458                         fib_info_hash_move(new_info_hash, new_laddrhash, new_size);
1459
1460                 if (!fib_info_hash_size)
1461                         goto failure;
1462         }
1463
1464         fi = kzalloc(struct_size(fi, fib_nh, nhs), GFP_KERNEL);
1465         if (!fi)
1466                 goto failure;
1467         fi->fib_metrics = ip_fib_metrics_init(fi->fib_net, cfg->fc_mx,
1468                                               cfg->fc_mx_len, extack);
1469         if (IS_ERR(fi->fib_metrics)) {
1470                 err = PTR_ERR(fi->fib_metrics);
1471                 kfree(fi);
1472                 return ERR_PTR(err);
1473         }
1474
1475         fi->fib_net = net;
1476         fi->fib_protocol = cfg->fc_protocol;
1477         fi->fib_scope = cfg->fc_scope;
1478         fi->fib_flags = cfg->fc_flags;
1479         fi->fib_priority = cfg->fc_priority;
1480         fi->fib_prefsrc = cfg->fc_prefsrc;
1481         fi->fib_type = cfg->fc_type;
1482         fi->fib_tb_id = cfg->fc_table;
1483
1484         fi->fib_nhs = nhs;
1485         if (nh) {
1486                 if (!nexthop_get(nh)) {
1487                         NL_SET_ERR_MSG(extack, "Nexthop has been deleted");
1488                         err = -EINVAL;
1489                 } else {
1490                         err = 0;
1491                         fi->nh = nh;
1492                 }
1493         } else {
1494                 change_nexthops(fi) {
1495                         nexthop_nh->nh_parent = fi;
1496                 } endfor_nexthops(fi)
1497
1498                 if (cfg->fc_mp)
1499                         err = fib_get_nhs(fi, cfg->fc_mp, cfg->fc_mp_len, cfg,
1500                                           extack);
1501                 else
1502                         err = fib_nh_init(net, fi->fib_nh, cfg, 1, extack);
1503         }
1504
1505         if (err != 0)
1506                 goto failure;
1507
1508         if (fib_props[cfg->fc_type].error) {
1509                 if (cfg->fc_gw_family || cfg->fc_oif || cfg->fc_mp) {
1510                         NL_SET_ERR_MSG(extack,
1511                                        "Gateway, device and multipath can not be specified for this route type");
1512                         goto err_inval;
1513                 }
1514                 goto link_it;
1515         } else {
1516                 switch (cfg->fc_type) {
1517                 case RTN_UNICAST:
1518                 case RTN_LOCAL:
1519                 case RTN_BROADCAST:
1520                 case RTN_ANYCAST:
1521                 case RTN_MULTICAST:
1522                         break;
1523                 default:
1524                         NL_SET_ERR_MSG(extack, "Invalid route type");
1525                         goto err_inval;
1526                 }
1527         }
1528
1529         if (cfg->fc_scope > RT_SCOPE_HOST) {
1530                 NL_SET_ERR_MSG(extack, "Invalid scope");
1531                 goto err_inval;
1532         }
1533
1534         if (fi->nh) {
1535                 err = fib_check_nexthop(fi->nh, cfg->fc_scope, extack);
1536                 if (err)
1537                         goto failure;
1538         } else if (cfg->fc_scope == RT_SCOPE_HOST) {
1539                 struct fib_nh *nh = fi->fib_nh;
1540
1541                 /* Local address is added. */
1542                 if (nhs != 1) {
1543                         NL_SET_ERR_MSG(extack,
1544                                        "Route with host scope can not have multiple nexthops");
1545                         goto err_inval;
1546                 }
1547                 if (nh->fib_nh_gw_family) {
1548                         NL_SET_ERR_MSG(extack,
1549                                        "Route with host scope can not have a gateway");
1550                         goto err_inval;
1551                 }
1552                 nh->fib_nh_scope = RT_SCOPE_NOWHERE;
1553                 nh->fib_nh_dev = dev_get_by_index(net, nh->fib_nh_oif);
1554                 err = -ENODEV;
1555                 if (!nh->fib_nh_dev)
1556                         goto failure;
1557                 netdev_tracker_alloc(nh->fib_nh_dev, &nh->fib_nh_dev_tracker,
1558                                      GFP_KERNEL);
1559         } else {
1560                 int linkdown = 0;
1561
1562                 change_nexthops(fi) {
1563                         err = fib_check_nh(cfg->fc_nlinfo.nl_net, nexthop_nh,
1564                                            cfg->fc_table, cfg->fc_scope,
1565                                            extack);
1566                         if (err != 0)
1567                                 goto failure;
1568                         if (nexthop_nh->fib_nh_flags & RTNH_F_LINKDOWN)
1569                                 linkdown++;
1570                 } endfor_nexthops(fi)
1571                 if (linkdown == fi->fib_nhs)
1572                         fi->fib_flags |= RTNH_F_LINKDOWN;
1573         }
1574
1575         if (fi->fib_prefsrc && !fib_valid_prefsrc(cfg, fi->fib_prefsrc)) {
1576                 NL_SET_ERR_MSG(extack, "Invalid prefsrc address");
1577                 goto err_inval;
1578         }
1579
1580         if (!fi->nh) {
1581                 change_nexthops(fi) {
1582                         fib_info_update_nhc_saddr(net, &nexthop_nh->nh_common,
1583                                                   fi->fib_scope);
1584                         if (nexthop_nh->fib_nh_gw_family == AF_INET6)
1585                                 fi->fib_nh_is_v6 = true;
1586                 } endfor_nexthops(fi)
1587
1588                 fib_rebalance(fi);
1589         }
1590
1591 link_it:
1592         ofi = fib_find_info(fi);
1593         if (ofi) {
1594                 fi->fib_dead = 1;
1595                 free_fib_info(fi);
1596                 refcount_inc(&ofi->fib_treeref);
1597                 return ofi;
1598         }
1599
1600         refcount_set(&fi->fib_treeref, 1);
1601         refcount_set(&fi->fib_clntref, 1);
1602         spin_lock_bh(&fib_info_lock);
1603         fib_info_cnt++;
1604         hlist_add_head(&fi->fib_hash,
1605                        &fib_info_hash[fib_info_hashfn(fi)]);
1606         if (fi->fib_prefsrc) {
1607                 struct hlist_head *head;
1608
1609                 head = fib_info_laddrhash_bucket(net, fi->fib_prefsrc);
1610                 hlist_add_head(&fi->fib_lhash, head);
1611         }
1612         if (fi->nh) {
1613                 list_add(&fi->nh_list, &nh->fi_list);
1614         } else {
1615                 change_nexthops(fi) {
1616                         struct hlist_head *head;
1617
1618                         if (!nexthop_nh->fib_nh_dev)
1619                                 continue;
1620                         head = fib_info_devhash_bucket(nexthop_nh->fib_nh_dev);
1621                         hlist_add_head(&nexthop_nh->nh_hash, head);
1622                 } endfor_nexthops(fi)
1623         }
1624         spin_unlock_bh(&fib_info_lock);
1625         return fi;
1626
1627 err_inval:
1628         err = -EINVAL;
1629
1630 failure:
1631         if (fi) {
1632                 fi->fib_dead = 1;
1633                 free_fib_info(fi);
1634         }
1635
1636         return ERR_PTR(err);
1637 }
1638
1639 int fib_nexthop_info(struct sk_buff *skb, const struct fib_nh_common *nhc,
1640                      u8 rt_family, unsigned char *flags, bool skip_oif)
1641 {
1642         if (nhc->nhc_flags & RTNH_F_DEAD)
1643                 *flags |= RTNH_F_DEAD;
1644
1645         if (nhc->nhc_flags & RTNH_F_LINKDOWN) {
1646                 *flags |= RTNH_F_LINKDOWN;
1647
1648                 rcu_read_lock();
1649                 switch (nhc->nhc_family) {
1650                 case AF_INET:
1651                         if (ip_ignore_linkdown(nhc->nhc_dev))
1652                                 *flags |= RTNH_F_DEAD;
1653                         break;
1654                 case AF_INET6:
1655                         if (ip6_ignore_linkdown(nhc->nhc_dev))
1656                                 *flags |= RTNH_F_DEAD;
1657                         break;
1658                 }
1659                 rcu_read_unlock();
1660         }
1661
1662         switch (nhc->nhc_gw_family) {
1663         case AF_INET:
1664                 if (nla_put_in_addr(skb, RTA_GATEWAY, nhc->nhc_gw.ipv4))
1665                         goto nla_put_failure;
1666                 break;
1667         case AF_INET6:
1668                 /* if gateway family does not match nexthop family
1669                  * gateway is encoded as RTA_VIA
1670                  */
1671                 if (rt_family != nhc->nhc_gw_family) {
1672                         int alen = sizeof(struct in6_addr);
1673                         struct nlattr *nla;
1674                         struct rtvia *via;
1675
1676                         nla = nla_reserve(skb, RTA_VIA, alen + 2);
1677                         if (!nla)
1678                                 goto nla_put_failure;
1679
1680                         via = nla_data(nla);
1681                         via->rtvia_family = AF_INET6;
1682                         memcpy(via->rtvia_addr, &nhc->nhc_gw.ipv6, alen);
1683                 } else if (nla_put_in6_addr(skb, RTA_GATEWAY,
1684                                             &nhc->nhc_gw.ipv6) < 0) {
1685                         goto nla_put_failure;
1686                 }
1687                 break;
1688         }
1689
1690         *flags |= (nhc->nhc_flags &
1691                    (RTNH_F_ONLINK | RTNH_F_OFFLOAD | RTNH_F_TRAP));
1692
1693         if (!skip_oif && nhc->nhc_dev &&
1694             nla_put_u32(skb, RTA_OIF, nhc->nhc_dev->ifindex))
1695                 goto nla_put_failure;
1696
1697         if (nhc->nhc_lwtstate &&
1698             lwtunnel_fill_encap(skb, nhc->nhc_lwtstate,
1699                                 RTA_ENCAP, RTA_ENCAP_TYPE) < 0)
1700                 goto nla_put_failure;
1701
1702         return 0;
1703
1704 nla_put_failure:
1705         return -EMSGSIZE;
1706 }
1707 EXPORT_SYMBOL_GPL(fib_nexthop_info);
1708
1709 #if IS_ENABLED(CONFIG_IP_ROUTE_MULTIPATH) || IS_ENABLED(CONFIG_IPV6)
1710 int fib_add_nexthop(struct sk_buff *skb, const struct fib_nh_common *nhc,
1711                     int nh_weight, u8 rt_family, u32 nh_tclassid)
1712 {
1713         const struct net_device *dev = nhc->nhc_dev;
1714         struct rtnexthop *rtnh;
1715         unsigned char flags = 0;
1716
1717         rtnh = nla_reserve_nohdr(skb, sizeof(*rtnh));
1718         if (!rtnh)
1719                 goto nla_put_failure;
1720
1721         rtnh->rtnh_hops = nh_weight - 1;
1722         rtnh->rtnh_ifindex = dev ? dev->ifindex : 0;
1723
1724         if (fib_nexthop_info(skb, nhc, rt_family, &flags, true) < 0)
1725                 goto nla_put_failure;
1726
1727         rtnh->rtnh_flags = flags;
1728
1729         if (nh_tclassid && nla_put_u32(skb, RTA_FLOW, nh_tclassid))
1730                 goto nla_put_failure;
1731
1732         /* length of rtnetlink header + attributes */
1733         rtnh->rtnh_len = nlmsg_get_pos(skb) - (void *)rtnh;
1734
1735         return 0;
1736
1737 nla_put_failure:
1738         return -EMSGSIZE;
1739 }
1740 EXPORT_SYMBOL_GPL(fib_add_nexthop);
1741 #endif
1742
1743 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1744 static int fib_add_multipath(struct sk_buff *skb, struct fib_info *fi)
1745 {
1746         struct nlattr *mp;
1747
1748         mp = nla_nest_start_noflag(skb, RTA_MULTIPATH);
1749         if (!mp)
1750                 goto nla_put_failure;
1751
1752         if (unlikely(fi->nh)) {
1753                 if (nexthop_mpath_fill_node(skb, fi->nh, AF_INET) < 0)
1754                         goto nla_put_failure;
1755                 goto mp_end;
1756         }
1757
1758         for_nexthops(fi) {
1759                 u32 nh_tclassid = 0;
1760 #ifdef CONFIG_IP_ROUTE_CLASSID
1761                 nh_tclassid = nh->nh_tclassid;
1762 #endif
1763                 if (fib_add_nexthop(skb, &nh->nh_common, nh->fib_nh_weight,
1764                                     AF_INET, nh_tclassid) < 0)
1765                         goto nla_put_failure;
1766         } endfor_nexthops(fi);
1767
1768 mp_end:
1769         nla_nest_end(skb, mp);
1770
1771         return 0;
1772
1773 nla_put_failure:
1774         return -EMSGSIZE;
1775 }
1776 #else
1777 static int fib_add_multipath(struct sk_buff *skb, struct fib_info *fi)
1778 {
1779         return 0;
1780 }
1781 #endif
1782
1783 int fib_dump_info(struct sk_buff *skb, u32 portid, u32 seq, int event,
1784                   const struct fib_rt_info *fri, unsigned int flags)
1785 {
1786         unsigned int nhs = fib_info_num_path(fri->fi);
1787         struct fib_info *fi = fri->fi;
1788         u32 tb_id = fri->tb_id;
1789         struct nlmsghdr *nlh;
1790         struct rtmsg *rtm;
1791
1792         nlh = nlmsg_put(skb, portid, seq, event, sizeof(*rtm), flags);
1793         if (!nlh)
1794                 return -EMSGSIZE;
1795
1796         rtm = nlmsg_data(nlh);
1797         rtm->rtm_family = AF_INET;
1798         rtm->rtm_dst_len = fri->dst_len;
1799         rtm->rtm_src_len = 0;
1800         rtm->rtm_tos = fri->tos;
1801         if (tb_id < 256)
1802                 rtm->rtm_table = tb_id;
1803         else
1804                 rtm->rtm_table = RT_TABLE_COMPAT;
1805         if (nla_put_u32(skb, RTA_TABLE, tb_id))
1806                 goto nla_put_failure;
1807         rtm->rtm_type = fri->type;
1808         rtm->rtm_flags = fi->fib_flags;
1809         rtm->rtm_scope = fi->fib_scope;
1810         rtm->rtm_protocol = fi->fib_protocol;
1811
1812         if (rtm->rtm_dst_len &&
1813             nla_put_in_addr(skb, RTA_DST, fri->dst))
1814                 goto nla_put_failure;
1815         if (fi->fib_priority &&
1816             nla_put_u32(skb, RTA_PRIORITY, fi->fib_priority))
1817                 goto nla_put_failure;
1818         if (rtnetlink_put_metrics(skb, fi->fib_metrics->metrics) < 0)
1819                 goto nla_put_failure;
1820
1821         if (fi->fib_prefsrc &&
1822             nla_put_in_addr(skb, RTA_PREFSRC, fi->fib_prefsrc))
1823                 goto nla_put_failure;
1824
1825         if (fi->nh) {
1826                 if (nla_put_u32(skb, RTA_NH_ID, fi->nh->id))
1827                         goto nla_put_failure;
1828                 if (nexthop_is_blackhole(fi->nh))
1829                         rtm->rtm_type = RTN_BLACKHOLE;
1830                 if (!fi->fib_net->ipv4.sysctl_nexthop_compat_mode)
1831                         goto offload;
1832         }
1833
1834         if (nhs == 1) {
1835                 const struct fib_nh_common *nhc = fib_info_nhc(fi, 0);
1836                 unsigned char flags = 0;
1837
1838                 if (fib_nexthop_info(skb, nhc, AF_INET, &flags, false) < 0)
1839                         goto nla_put_failure;
1840
1841                 rtm->rtm_flags = flags;
1842 #ifdef CONFIG_IP_ROUTE_CLASSID
1843                 if (nhc->nhc_family == AF_INET) {
1844                         struct fib_nh *nh;
1845
1846                         nh = container_of(nhc, struct fib_nh, nh_common);
1847                         if (nh->nh_tclassid &&
1848                             nla_put_u32(skb, RTA_FLOW, nh->nh_tclassid))
1849                                 goto nla_put_failure;
1850                 }
1851 #endif
1852         } else {
1853                 if (fib_add_multipath(skb, fi) < 0)
1854                         goto nla_put_failure;
1855         }
1856
1857 offload:
1858         if (fri->offload)
1859                 rtm->rtm_flags |= RTM_F_OFFLOAD;
1860         if (fri->trap)
1861                 rtm->rtm_flags |= RTM_F_TRAP;
1862         if (fri->offload_failed)
1863                 rtm->rtm_flags |= RTM_F_OFFLOAD_FAILED;
1864
1865         nlmsg_end(skb, nlh);
1866         return 0;
1867
1868 nla_put_failure:
1869         nlmsg_cancel(skb, nlh);
1870         return -EMSGSIZE;
1871 }
1872
1873 /*
1874  * Update FIB if:
1875  * - local address disappeared -> we must delete all the entries
1876  *   referring to it.
1877  * - device went down -> we must shutdown all nexthops going via it.
1878  */
1879 int fib_sync_down_addr(struct net_device *dev, __be32 local)
1880 {
1881         int tb_id = l3mdev_fib_table(dev) ? : RT_TABLE_MAIN;
1882         struct net *net = dev_net(dev);
1883         struct hlist_head *head;
1884         struct fib_info *fi;
1885         int ret = 0;
1886
1887         if (!fib_info_laddrhash || local == 0)
1888                 return 0;
1889
1890         head = fib_info_laddrhash_bucket(net, local);
1891         hlist_for_each_entry(fi, head, fib_lhash) {
1892                 if (!net_eq(fi->fib_net, net) ||
1893                     fi->fib_tb_id != tb_id)
1894                         continue;
1895                 if (fi->fib_prefsrc == local) {
1896                         fi->fib_flags |= RTNH_F_DEAD;
1897                         ret++;
1898                 }
1899         }
1900         return ret;
1901 }
1902
1903 static int call_fib_nh_notifiers(struct fib_nh *nh,
1904                                  enum fib_event_type event_type)
1905 {
1906         bool ignore_link_down = ip_ignore_linkdown(nh->fib_nh_dev);
1907         struct fib_nh_notifier_info info = {
1908                 .fib_nh = nh,
1909         };
1910
1911         switch (event_type) {
1912         case FIB_EVENT_NH_ADD:
1913                 if (nh->fib_nh_flags & RTNH_F_DEAD)
1914                         break;
1915                 if (ignore_link_down && nh->fib_nh_flags & RTNH_F_LINKDOWN)
1916                         break;
1917                 return call_fib4_notifiers(dev_net(nh->fib_nh_dev), event_type,
1918                                            &info.info);
1919         case FIB_EVENT_NH_DEL:
1920                 if ((ignore_link_down && nh->fib_nh_flags & RTNH_F_LINKDOWN) ||
1921                     (nh->fib_nh_flags & RTNH_F_DEAD))
1922                         return call_fib4_notifiers(dev_net(nh->fib_nh_dev),
1923                                                    event_type, &info.info);
1924                 break;
1925         default:
1926                 break;
1927         }
1928
1929         return NOTIFY_DONE;
1930 }
1931
1932 /* Update the PMTU of exceptions when:
1933  * - the new MTU of the first hop becomes smaller than the PMTU
1934  * - the old MTU was the same as the PMTU, and it limited discovery of
1935  *   larger MTUs on the path. With that limit raised, we can now
1936  *   discover larger MTUs
1937  * A special case is locked exceptions, for which the PMTU is smaller
1938  * than the minimal accepted PMTU:
1939  * - if the new MTU is greater than the PMTU, don't make any change
1940  * - otherwise, unlock and set PMTU
1941  */
1942 void fib_nhc_update_mtu(struct fib_nh_common *nhc, u32 new, u32 orig)
1943 {
1944         struct fnhe_hash_bucket *bucket;
1945         int i;
1946
1947         bucket = rcu_dereference_protected(nhc->nhc_exceptions, 1);
1948         if (!bucket)
1949                 return;
1950
1951         for (i = 0; i < FNHE_HASH_SIZE; i++) {
1952                 struct fib_nh_exception *fnhe;
1953
1954                 for (fnhe = rcu_dereference_protected(bucket[i].chain, 1);
1955                      fnhe;
1956                      fnhe = rcu_dereference_protected(fnhe->fnhe_next, 1)) {
1957                         if (fnhe->fnhe_mtu_locked) {
1958                                 if (new <= fnhe->fnhe_pmtu) {
1959                                         fnhe->fnhe_pmtu = new;
1960                                         fnhe->fnhe_mtu_locked = false;
1961                                 }
1962                         } else if (new < fnhe->fnhe_pmtu ||
1963                                    orig == fnhe->fnhe_pmtu) {
1964                                 fnhe->fnhe_pmtu = new;
1965                         }
1966                 }
1967         }
1968 }
1969
1970 void fib_sync_mtu(struct net_device *dev, u32 orig_mtu)
1971 {
1972         struct hlist_head *head = fib_info_devhash_bucket(dev);
1973         struct fib_nh *nh;
1974
1975         hlist_for_each_entry(nh, head, nh_hash) {
1976                 if (nh->fib_nh_dev == dev)
1977                         fib_nhc_update_mtu(&nh->nh_common, dev->mtu, orig_mtu);
1978         }
1979 }
1980
1981 /* Event              force Flags           Description
1982  * NETDEV_CHANGE      0     LINKDOWN        Carrier OFF, not for scope host
1983  * NETDEV_DOWN        0     LINKDOWN|DEAD   Link down, not for scope host
1984  * NETDEV_DOWN        1     LINKDOWN|DEAD   Last address removed
1985  * NETDEV_UNREGISTER  1     LINKDOWN|DEAD   Device removed
1986  *
1987  * only used when fib_nh is built into fib_info
1988  */
1989 int fib_sync_down_dev(struct net_device *dev, unsigned long event, bool force)
1990 {
1991         struct hlist_head *head = fib_info_devhash_bucket(dev);
1992         struct fib_info *prev_fi = NULL;
1993         int scope = RT_SCOPE_NOWHERE;
1994         struct fib_nh *nh;
1995         int ret = 0;
1996
1997         if (force)
1998                 scope = -1;
1999
2000         hlist_for_each_entry(nh, head, nh_hash) {
2001                 struct fib_info *fi = nh->nh_parent;
2002                 int dead;
2003
2004                 BUG_ON(!fi->fib_nhs);
2005                 if (nh->fib_nh_dev != dev || fi == prev_fi)
2006                         continue;
2007                 prev_fi = fi;
2008                 dead = 0;
2009                 change_nexthops(fi) {
2010                         if (nexthop_nh->fib_nh_flags & RTNH_F_DEAD)
2011                                 dead++;
2012                         else if (nexthop_nh->fib_nh_dev == dev &&
2013                                  nexthop_nh->fib_nh_scope != scope) {
2014                                 switch (event) {
2015                                 case NETDEV_DOWN:
2016                                 case NETDEV_UNREGISTER:
2017                                         nexthop_nh->fib_nh_flags |= RTNH_F_DEAD;
2018                                         fallthrough;
2019                                 case NETDEV_CHANGE:
2020                                         nexthop_nh->fib_nh_flags |= RTNH_F_LINKDOWN;
2021                                         break;
2022                                 }
2023                                 call_fib_nh_notifiers(nexthop_nh,
2024                                                       FIB_EVENT_NH_DEL);
2025                                 dead++;
2026                         }
2027 #ifdef CONFIG_IP_ROUTE_MULTIPATH
2028                         if (event == NETDEV_UNREGISTER &&
2029                             nexthop_nh->fib_nh_dev == dev) {
2030                                 dead = fi->fib_nhs;
2031                                 break;
2032                         }
2033 #endif
2034                 } endfor_nexthops(fi)
2035                 if (dead == fi->fib_nhs) {
2036                         switch (event) {
2037                         case NETDEV_DOWN:
2038                         case NETDEV_UNREGISTER:
2039                                 fi->fib_flags |= RTNH_F_DEAD;
2040                                 fallthrough;
2041                         case NETDEV_CHANGE:
2042                                 fi->fib_flags |= RTNH_F_LINKDOWN;
2043                                 break;
2044                         }
2045                         ret++;
2046                 }
2047
2048                 fib_rebalance(fi);
2049         }
2050
2051         return ret;
2052 }
2053
2054 /* Must be invoked inside of an RCU protected region.  */
2055 static void fib_select_default(const struct flowi4 *flp, struct fib_result *res)
2056 {
2057         struct fib_info *fi = NULL, *last_resort = NULL;
2058         struct hlist_head *fa_head = res->fa_head;
2059         struct fib_table *tb = res->table;
2060         u8 slen = 32 - res->prefixlen;
2061         int order = -1, last_idx = -1;
2062         struct fib_alias *fa, *fa1 = NULL;
2063         u32 last_prio = res->fi->fib_priority;
2064         u8 last_tos = 0;
2065
2066         hlist_for_each_entry_rcu(fa, fa_head, fa_list) {
2067                 struct fib_info *next_fi = fa->fa_info;
2068                 struct fib_nh_common *nhc;
2069
2070                 if (fa->fa_slen != slen)
2071                         continue;
2072                 if (fa->fa_tos && fa->fa_tos != flp->flowi4_tos)
2073                         continue;
2074                 if (fa->tb_id != tb->tb_id)
2075                         continue;
2076                 if (next_fi->fib_priority > last_prio &&
2077                     fa->fa_tos == last_tos) {
2078                         if (last_tos)
2079                                 continue;
2080                         break;
2081                 }
2082                 if (next_fi->fib_flags & RTNH_F_DEAD)
2083                         continue;
2084                 last_tos = fa->fa_tos;
2085                 last_prio = next_fi->fib_priority;
2086
2087                 if (next_fi->fib_scope != res->scope ||
2088                     fa->fa_type != RTN_UNICAST)
2089                         continue;
2090
2091                 nhc = fib_info_nhc(next_fi, 0);
2092                 if (!nhc->nhc_gw_family || nhc->nhc_scope != RT_SCOPE_LINK)
2093                         continue;
2094
2095                 fib_alias_accessed(fa);
2096
2097                 if (!fi) {
2098                         if (next_fi != res->fi)
2099                                 break;
2100                         fa1 = fa;
2101                 } else if (!fib_detect_death(fi, order, &last_resort,
2102                                              &last_idx, fa1->fa_default)) {
2103                         fib_result_assign(res, fi);
2104                         fa1->fa_default = order;
2105                         goto out;
2106                 }
2107                 fi = next_fi;
2108                 order++;
2109         }
2110
2111         if (order <= 0 || !fi) {
2112                 if (fa1)
2113                         fa1->fa_default = -1;
2114                 goto out;
2115         }
2116
2117         if (!fib_detect_death(fi, order, &last_resort, &last_idx,
2118                               fa1->fa_default)) {
2119                 fib_result_assign(res, fi);
2120                 fa1->fa_default = order;
2121                 goto out;
2122         }
2123
2124         if (last_idx >= 0)
2125                 fib_result_assign(res, last_resort);
2126         fa1->fa_default = last_idx;
2127 out:
2128         return;
2129 }
2130
2131 /*
2132  * Dead device goes up. We wake up dead nexthops.
2133  * It takes sense only on multipath routes.
2134  *
2135  * only used when fib_nh is built into fib_info
2136  */
2137 int fib_sync_up(struct net_device *dev, unsigned char nh_flags)
2138 {
2139         struct fib_info *prev_fi;
2140         struct hlist_head *head;
2141         struct fib_nh *nh;
2142         int ret;
2143
2144         if (!(dev->flags & IFF_UP))
2145                 return 0;
2146
2147         if (nh_flags & RTNH_F_DEAD) {
2148                 unsigned int flags = dev_get_flags(dev);
2149
2150                 if (flags & (IFF_RUNNING | IFF_LOWER_UP))
2151                         nh_flags |= RTNH_F_LINKDOWN;
2152         }
2153
2154         prev_fi = NULL;
2155         head = fib_info_devhash_bucket(dev);
2156         ret = 0;
2157
2158         hlist_for_each_entry(nh, head, nh_hash) {
2159                 struct fib_info *fi = nh->nh_parent;
2160                 int alive;
2161
2162                 BUG_ON(!fi->fib_nhs);
2163                 if (nh->fib_nh_dev != dev || fi == prev_fi)
2164                         continue;
2165
2166                 prev_fi = fi;
2167                 alive = 0;
2168                 change_nexthops(fi) {
2169                         if (!(nexthop_nh->fib_nh_flags & nh_flags)) {
2170                                 alive++;
2171                                 continue;
2172                         }
2173                         if (!nexthop_nh->fib_nh_dev ||
2174                             !(nexthop_nh->fib_nh_dev->flags & IFF_UP))
2175                                 continue;
2176                         if (nexthop_nh->fib_nh_dev != dev ||
2177                             !__in_dev_get_rtnl(dev))
2178                                 continue;
2179                         alive++;
2180                         nexthop_nh->fib_nh_flags &= ~nh_flags;
2181                         call_fib_nh_notifiers(nexthop_nh, FIB_EVENT_NH_ADD);
2182                 } endfor_nexthops(fi)
2183
2184                 if (alive > 0) {
2185                         fi->fib_flags &= ~nh_flags;
2186                         ret++;
2187                 }
2188
2189                 fib_rebalance(fi);
2190         }
2191
2192         return ret;
2193 }
2194
2195 #ifdef CONFIG_IP_ROUTE_MULTIPATH
2196 static bool fib_good_nh(const struct fib_nh *nh)
2197 {
2198         int state = NUD_REACHABLE;
2199
2200         if (nh->fib_nh_scope == RT_SCOPE_LINK) {
2201                 struct neighbour *n;
2202
2203                 rcu_read_lock_bh();
2204
2205                 if (likely(nh->fib_nh_gw_family == AF_INET))
2206                         n = __ipv4_neigh_lookup_noref(nh->fib_nh_dev,
2207                                                    (__force u32)nh->fib_nh_gw4);
2208                 else if (nh->fib_nh_gw_family == AF_INET6)
2209                         n = __ipv6_neigh_lookup_noref_stub(nh->fib_nh_dev,
2210                                                            &nh->fib_nh_gw6);
2211                 else
2212                         n = NULL;
2213                 if (n)
2214                         state = n->nud_state;
2215
2216                 rcu_read_unlock_bh();
2217         }
2218
2219         return !!(state & NUD_VALID);
2220 }
2221
2222 void fib_select_multipath(struct fib_result *res, int hash)
2223 {
2224         struct fib_info *fi = res->fi;
2225         struct net *net = fi->fib_net;
2226         bool first = false;
2227
2228         if (unlikely(res->fi->nh)) {
2229                 nexthop_path_fib_result(res, hash);
2230                 return;
2231         }
2232
2233         change_nexthops(fi) {
2234                 if (net->ipv4.sysctl_fib_multipath_use_neigh) {
2235                         if (!fib_good_nh(nexthop_nh))
2236                                 continue;
2237                         if (!first) {
2238                                 res->nh_sel = nhsel;
2239                                 res->nhc = &nexthop_nh->nh_common;
2240                                 first = true;
2241                         }
2242                 }
2243
2244                 if (hash > atomic_read(&nexthop_nh->fib_nh_upper_bound))
2245                         continue;
2246
2247                 res->nh_sel = nhsel;
2248                 res->nhc = &nexthop_nh->nh_common;
2249                 return;
2250         } endfor_nexthops(fi);
2251 }
2252 #endif
2253
2254 void fib_select_path(struct net *net, struct fib_result *res,
2255                      struct flowi4 *fl4, const struct sk_buff *skb)
2256 {
2257         if (fl4->flowi4_oif && !(fl4->flowi4_flags & FLOWI_FLAG_SKIP_NH_OIF))
2258                 goto check_saddr;
2259
2260 #ifdef CONFIG_IP_ROUTE_MULTIPATH
2261         if (fib_info_num_path(res->fi) > 1) {
2262                 int h = fib_multipath_hash(net, fl4, skb, NULL);
2263
2264                 fib_select_multipath(res, h);
2265         }
2266         else
2267 #endif
2268         if (!res->prefixlen &&
2269             res->table->tb_num_default > 1 &&
2270             res->type == RTN_UNICAST)
2271                 fib_select_default(fl4, res);
2272
2273 check_saddr:
2274         if (!fl4->saddr)
2275                 fl4->saddr = fib_result_prefsrc(net, res);
2276 }