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