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