net/ipv4/fib_semantics.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * INET         An implementation of the TCP/IP protocol suite for the LINUX
   4  *              operating system.  INET is implemented using the  BSD Socket
   5  *              interface as the means of communication with the user level.
   6  *
   7  *              IPv4 Forwarding Information Base: semantics.
   8  *
   9  * Authors:     Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
  10  */
  11
  12 #include <linux/uaccess.h>
  13 #include <linux/bitops.h>
  14 #include <linux/types.h>
  15 #include <linux/kernel.h>
  16 #include <linux/jiffies.h>
  17 #include <linux/mm.h>
  18 #include <linux/string.h>
  19 #include <linux/socket.h>
  20 #include <linux/sockios.h>
  21 #include <linux/errno.h>
  22 #include <linux/in.h>
  23 #include <linux/inet.h>
  24 #include <linux/inetdevice.h>
  25 #include <linux/netdevice.h>
  26 #include <linux/if_arp.h>
  27 #include <linux/proc_fs.h>
  28 #include <linux/skbuff.h>
  29 #include <linux/init.h>
  30 #include <linux/slab.h>
  31 #include <linux/netlink.h>
  32 #include <linux/hash.h>
  33 #include <linux/nospec.h>
  34
  35 #include <net/arp.h>
  36 #include <net/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_cnt;
  57
  58 #define DEVINDEX_HASHBITS 8
  59 #define DEVINDEX_HASHSIZE (1U << DEVINDEX_HASHBITS)
  60 static struct hlist_head fib_info_devhash[DEVINDEX_HASHSIZE];
  61
  62 /* for_nexthops and change_nexthops only used when nexthop object
  63  * is not set in a fib_info. The logic within can reference fib_nh.
  64  */
  65 #ifdef CONFIG_IP_ROUTE_MULTIPATH
  66
  67 #define for_nexthops(fi) {                                              \
  68         int nhsel; const struct fib_nh *nh;                             \
  69         for (nhsel = 0, nh = (fi)->fib_nh;                              \
  70              nhsel < fib_info_num_path((fi));                           \
  71              nh++, nhsel++)
  72
  73 #define change_nexthops(fi) {                                           \
  74         int nhsel; struct fib_nh *nexthop_nh;                           \
  75         for (nhsel = 0, nexthop_nh = (struct fib_nh *)((fi)->fib_nh);   \
  76              nhsel < fib_info_num_path((fi));                           \
  77              nexthop_nh++, nhsel++)
  78
  79 #else /* CONFIG_IP_ROUTE_MULTIPATH */
  80
  81 /* Hope, that gcc will optimize it to get rid of dummy loop */
  82
  83 #define for_nexthops(fi) {                                              \
  84         int nhsel; const struct fib_nh *nh = (fi)->fib_nh;              \
  85         for (nhsel = 0; nhsel < 1; nhsel++)
  86
  87 #define change_nexthops(fi) {                                           \
  88         int nhsel;                                                      \
  89         struct fib_nh *nexthop_nh = (struct fib_nh *)((fi)->fib_nh);    \
  90         for (nhsel = 0; nhsel < 1; nhsel++)
  91
  92 #endif /* CONFIG_IP_ROUTE_MULTIPATH */
  93
  94 #define endfor_nexthops(fi) }
  95
  96
  97 const struct fib_prop fib_props[RTN_MAX + 1] = {
  98         [RTN_UNSPEC] = {
  99                 .error  = 0,
 100                 .scope  = RT_SCOPE_NOWHERE,
 101         },
 102         [RTN_UNICAST] = {
 103                 .error  = 0,
 104                 .scope  = RT_SCOPE_UNIVERSE,
 105         },
 106         [RTN_LOCAL] = {
 107                 .error  = 0,
 108                 .scope  = RT_SCOPE_HOST,
 109         },
 110         [RTN_BROADCAST] = {
 111                 .error  = 0,
 112                 .scope  = RT_SCOPE_LINK,
 113         },
 114         [RTN_ANYCAST] = {
 115                 .error  = 0,
 116                 .scope  = RT_SCOPE_LINK,
 117         },
 118         [RTN_MULTICAST] = {
 119                 .error  = 0,
 120                 .scope  = RT_SCOPE_UNIVERSE,
 121         },
 122         [RTN_BLACKHOLE] = {
 123                 .error  = -EINVAL,
 124                 .scope  = RT_SCOPE_UNIVERSE,
 125         },
 126         [RTN_UNREACHABLE] = {
 127                 .error  = -EHOSTUNREACH,
 128                 .scope  = RT_SCOPE_UNIVERSE,
 129         },
 130         [RTN_PROHIBIT] = {
 131                 .error  = -EACCES,
 132                 .scope  = RT_SCOPE_UNIVERSE,
 133         },
 134         [RTN_THROW] = {
 135                 .error  = -EAGAIN,
 136                 .scope  = RT_SCOPE_UNIVERSE,
 137         },
 138         [RTN_NAT] = {
 139                 .error  = -EINVAL,
 140                 .scope  = RT_SCOPE_NOWHERE,
 141         },
 142         [RTN_XRESOLVE] = {
 143                 .error  = -EINVAL,
 144                 .scope  = RT_SCOPE_NOWHERE,
 145         },
 146 };
 147
 148 static void rt_fibinfo_free(struct rtable __rcu **rtp)
 149 {
 150         struct rtable *rt = rcu_dereference_protected(*rtp, 1);
 151
 152         if (!rt)
 153                 return;
 154
 155         /* Not even needed : RCU_INIT_POINTER(*rtp, NULL);
 156          * because we waited an RCU grace period before calling
 157          * free_fib_info_rcu()
 158          */
 159
 160         dst_dev_put(&rt->dst);
 161         dst_release_immediate(&rt->dst);
 162 }
 163
 164 static void free_nh_exceptions(struct fib_nh_common *nhc)
 165 {
 166         struct fnhe_hash_bucket *hash;
 167         int i;
 168
 169         hash = rcu_dereference_protected(nhc->nhc_exceptions, 1);
 170         if (!hash)
 171                 return;
 172         for (i = 0; i < FNHE_HASH_SIZE; i++) {
 173                 struct fib_nh_exception *fnhe;
 174
 175                 fnhe = rcu_dereference_protected(hash[i].chain, 1);
 176                 while (fnhe) {
 177                         struct fib_nh_exception *next;
 178
 179                         next = rcu_dereference_protected(fnhe->fnhe_next, 1);
 180
 181                         rt_fibinfo_free(&fnhe->fnhe_rth_input);
 182                         rt_fibinfo_free(&fnhe->fnhe_rth_output);
 183
 184                         kfree(fnhe);
 185
 186                         fnhe = next;
 187                 }
 188         }
 189         kfree(hash);
 190 }
 191
 192 static void rt_fibinfo_free_cpus(struct rtable __rcu * __percpu *rtp)
 193 {
 194         int cpu;
 195
 196         if (!rtp)
 197                 return;
 198
 199         for_each_possible_cpu(cpu) {
 200                 struct rtable *rt;
 201
 202                 rt = rcu_dereference_protected(*per_cpu_ptr(rtp, cpu), 1);
 203                 if (rt) {
 204                         dst_dev_put(&rt->dst);
 205                         dst_release_immediate(&rt->dst);
 206                 }
 207         }
 208         free_percpu(rtp);
 209 }
 210
 211 void fib_nh_common_release(struct fib_nh_common *nhc)
 212 {
 213         if (nhc->nhc_dev)
 214                 dev_put(nhc->nhc_dev);
 215
 216         lwtstate_put(nhc->nhc_lwtstate);
 217         rt_fibinfo_free_cpus(nhc->nhc_pcpu_rth_output);
 218         rt_fibinfo_free(&nhc->nhc_rth_input);
 219         free_nh_exceptions(nhc);
 220 }
 221 EXPORT_SYMBOL_GPL(fib_nh_common_release);
 222
 223 void fib_nh_release(struct net *net, struct fib_nh *fib_nh)
 224 {
 225 #ifdef CONFIG_IP_ROUTE_CLASSID
 226         if (fib_nh->nh_tclassid)
 227                 atomic_dec(&net->ipv4.fib_num_tclassid_users);
 228 #endif
 229         fib_nh_common_release(&fib_nh->nh_common);
 230 }
 231
 232 /* Release a nexthop info record */
 233 static void free_fib_info_rcu(struct rcu_head *head)
 234 {
 235         struct fib_info *fi = container_of(head, struct fib_info, rcu);
 236
 237         if (fi->nh) {
 238                 nexthop_put(fi->nh);
 239         } else {
 240                 change_nexthops(fi) {
 241                         fib_nh_release(fi->fib_net, nexthop_nh);
 242                 } endfor_nexthops(fi);
 243         }
 244
 245         ip_fib_metrics_put(fi->fib_metrics);
 246
 247         kfree(fi);
 248 }
 249
 250 void free_fib_info(struct fib_info *fi)
 251 {
 252         if (fi->fib_dead == 0) {
 253                 pr_warn("Freeing alive fib_info %p\n", fi);
 254                 return;
 255         }
 256         fib_info_cnt--;
 257
 258         call_rcu(&fi->rcu, free_fib_info_rcu);
 259 }
 260 EXPORT_SYMBOL_GPL(free_fib_info);
 261
 262 void fib_release_info(struct fib_info *fi)
 263 {
 264         spin_lock_bh(&fib_info_lock);
 265         if (fi && --fi->fib_treeref == 0) {
 266                 hlist_del(&fi->fib_hash);
 267                 if (fi->fib_prefsrc)
 268                         hlist_del(&fi->fib_lhash);
 269                 if (fi->nh) {
 270                         list_del(&fi->nh_list);
 271                 } else {
 272                         change_nexthops(fi) {
 273                                 if (!nexthop_nh->fib_nh_dev)
 274                                         continue;
 275                                 hlist_del(&nexthop_nh->nh_hash);
 276                         } endfor_nexthops(fi)
 277                 }
 278                 /* Paired with READ_ONCE() from fib_table_lookup() */
 279                 WRITE_ONCE(fi->fib_dead, 1);
 280                 fib_info_put(fi);
 281         }
 282         spin_unlock_bh(&fib_info_lock);
 283 }
 284
 285 static inline int nh_comp(struct fib_info *fi, struct fib_info *ofi)
 286 {
 287         const struct fib_nh *onh;
 288
 289         if (fi->nh || ofi->nh)
 290                 return nexthop_cmp(fi->nh, ofi->nh) ? 0 : -1;
 291
 292         if (ofi->fib_nhs == 0)
 293                 return 0;
 294
 295         for_nexthops(fi) {
 296                 onh = fib_info_nh(ofi, nhsel);
 297
 298                 if (nh->fib_nh_oif != onh->fib_nh_oif ||
 299                     nh->fib_nh_gw_family != onh->fib_nh_gw_family ||
 300                     nh->fib_nh_scope != onh->fib_nh_scope ||
 301 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 302                     nh->fib_nh_weight != onh->fib_nh_weight ||
 303 #endif
 304 #ifdef CONFIG_IP_ROUTE_CLASSID
 305                     nh->nh_tclassid != onh->nh_tclassid ||
 306 #endif
 307                     lwtunnel_cmp_encap(nh->fib_nh_lws, onh->fib_nh_lws) ||
 308                     ((nh->fib_nh_flags ^ onh->fib_nh_flags) & ~RTNH_COMPARE_MASK))
 309                         return -1;
 310
 311                 if (nh->fib_nh_gw_family == AF_INET &&
 312                     nh->fib_nh_gw4 != onh->fib_nh_gw4)
 313                         return -1;
 314
 315                 if (nh->fib_nh_gw_family == AF_INET6 &&
 316                     ipv6_addr_cmp(&nh->fib_nh_gw6, &onh->fib_nh_gw6))
 317                         return -1;
 318         } endfor_nexthops(fi);
 319         return 0;
 320 }
 321
 322 static inline unsigned int fib_devindex_hashfn(unsigned int val)
 323 {
 324         return hash_32(val, DEVINDEX_HASHBITS);
 325 }
 326
 327 static struct hlist_head *
 328 fib_info_devhash_bucket(const struct net_device *dev)
 329 {
 330         u32 val = net_hash_mix(dev_net(dev)) ^ dev->ifindex;
 331
 332         return &fib_info_devhash[fib_devindex_hashfn(val)];
 333 }
 334
 335 static unsigned int fib_info_hashfn_1(int init_val, u8 protocol, u8 scope,
 336                                       u32 prefsrc, u32 priority)
 337 {
 338         unsigned int val = init_val;
 339
 340         val ^= (protocol << 8) | scope;
 341         val ^= prefsrc;
 342         val ^= priority;
 343
 344         return val;
 345 }
 346
 347 static unsigned int fib_info_hashfn_result(unsigned int val)
 348 {
 349         unsigned int mask = (fib_info_hash_size - 1);
 350
 351         return (val ^ (val >> 7) ^ (val >> 12)) & mask;
 352 }
 353
 354 static inline unsigned int fib_info_hashfn(struct fib_info *fi)
 355 {
 356         unsigned int val;
 357
 358         val = fib_info_hashfn_1(fi->fib_nhs, fi->fib_protocol,
 359                                 fi->fib_scope, (__force u32)fi->fib_prefsrc,
 360                                 fi->fib_priority);
 361
 362         if (fi->nh) {
 363                 val ^= fib_devindex_hashfn(fi->nh->id);
 364         } else {
 365                 for_nexthops(fi) {
 366                         val ^= fib_devindex_hashfn(nh->fib_nh_oif);
 367                 } endfor_nexthops(fi)
 368         }
 369
 370         return fib_info_hashfn_result(val);
 371 }
 372
 373 /* no metrics, only nexthop id */
 374 static struct fib_info *fib_find_info_nh(struct net *net,
 375                                          const struct fib_config *cfg)
 376 {
 377         struct hlist_head *head;
 378         struct fib_info *fi;
 379         unsigned int hash;
 380
 381         hash = fib_info_hashfn_1(fib_devindex_hashfn(cfg->fc_nh_id),
 382                                  cfg->fc_protocol, cfg->fc_scope,
 383                                  (__force u32)cfg->fc_prefsrc,
 384                                  cfg->fc_priority);
 385         hash = fib_info_hashfn_result(hash);
 386         head = &fib_info_hash[hash];
 387
 388         hlist_for_each_entry(fi, head, fib_hash) {
 389                 if (!net_eq(fi->fib_net, net))
 390                         continue;
 391                 if (!fi->nh || fi->nh->id != cfg->fc_nh_id)
 392                         continue;
 393                 if (cfg->fc_protocol == fi->fib_protocol &&
 394                     cfg->fc_scope == fi->fib_scope &&
 395                     cfg->fc_prefsrc == fi->fib_prefsrc &&
 396                     cfg->fc_priority == fi->fib_priority &&
 397                     cfg->fc_type == fi->fib_type &&
 398                     cfg->fc_table == fi->fib_tb_id &&
 399                     !((cfg->fc_flags ^ fi->fib_flags) & ~RTNH_COMPARE_MASK))
 400                         return fi;
 401         }
 402
 403         return NULL;
 404 }
 405
 406 static struct fib_info *fib_find_info(struct fib_info *nfi)
 407 {
 408         struct hlist_head *head;
 409         struct fib_info *fi;
 410         unsigned int hash;
 411
 412         hash = fib_info_hashfn(nfi);
 413         head = &fib_info_hash[hash];
 414
 415         hlist_for_each_entry(fi, head, fib_hash) {
 416                 if (!net_eq(fi->fib_net, nfi->fib_net))
 417                         continue;
 418                 if (fi->fib_nhs != nfi->fib_nhs)
 419                         continue;
 420                 if (nfi->fib_protocol == fi->fib_protocol &&
 421                     nfi->fib_scope == fi->fib_scope &&
 422                     nfi->fib_prefsrc == fi->fib_prefsrc &&
 423                     nfi->fib_priority == fi->fib_priority &&
 424                     nfi->fib_type == fi->fib_type &&
 425                     nfi->fib_tb_id == fi->fib_tb_id &&
 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 static inline 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 sk_buff *skb;
 515         u32 seq = info->nlh ? info->nlh->nlmsg_seq : 0;
 516         int err = -ENOBUFS;
 517
 518         skb = nlmsg_new(fib_nlmsg_size(fa->fa_info), GFP_KERNEL);
 519         if (!skb)
 520                 goto errout;
 521
 522         err = fib_dump_info(skb, info->portid, seq, event, tb_id,
 523                             fa->fa_type, key, dst_len,
 524                             fa->fa_tos, fa->fa_info, nlm_flags);
 525         if (err < 0) {
 526                 /* -EMSGSIZE implies BUG in fib_nlmsg_size() */
 527                 WARN_ON(err == -EMSGSIZE);
 528                 kfree_skb(skb);
 529                 goto errout;
 530         }
 531         rtnl_notify(skb, info->nl_net, info->portid, RTNLGRP_IPV4_ROUTE,
 532                     info->nlh, GFP_KERNEL);
 533         return;
 534 errout:
 535         if (err < 0)
 536                 rtnl_set_sk_err(info->nl_net, RTNLGRP_IPV4_ROUTE, err);
 537 }
 538
 539 static int fib_detect_death(struct fib_info *fi, int order,
 540                             struct fib_info **last_resort, int *last_idx,
 541                             int dflt)
 542 {
 543         const struct fib_nh_common *nhc = fib_info_nhc(fi, 0);
 544         struct neighbour *n;
 545         int state = NUD_NONE;
 546
 547         if (likely(nhc->nhc_gw_family == AF_INET))
 548                 n = neigh_lookup(&arp_tbl, &nhc->nhc_gw.ipv4, nhc->nhc_dev);
 549         else if (nhc->nhc_gw_family == AF_INET6)
 550                 n = neigh_lookup(ipv6_stub->nd_tbl, &nhc->nhc_gw.ipv6,
 551                                  nhc->nhc_dev);
 552         else
 553                 n = NULL;
 554
 555         if (n) {
 556                 state = n->nud_state;
 557                 neigh_release(n);
 558         } else {
 559                 return 0;
 560         }
 561         if (state == NUD_REACHABLE)
 562                 return 0;
 563         if ((state & NUD_VALID) && order != dflt)
 564                 return 0;
 565         if ((state & NUD_VALID) ||
 566             (*last_idx < 0 && order > dflt && state != NUD_INCOMPLETE)) {
 567                 *last_resort = fi;
 568                 *last_idx = order;
 569         }
 570         return 1;
 571 }
 572
 573 int fib_nh_common_init(struct fib_nh_common *nhc, struct nlattr *encap,
 574                        u16 encap_type, void *cfg, gfp_t gfp_flags,
 575                        struct netlink_ext_ack *extack)
 576 {
 577         int err;
 578
 579         nhc->nhc_pcpu_rth_output = alloc_percpu_gfp(struct rtable __rcu *,
 580                                                     gfp_flags);
 581         if (!nhc->nhc_pcpu_rth_output)
 582                 return -ENOMEM;
 583
 584         if (encap) {
 585                 struct lwtunnel_state *lwtstate;
 586
 587                 if (encap_type == LWTUNNEL_ENCAP_NONE) {
 588                         NL_SET_ERR_MSG(extack, "LWT encap type not specified");
 589                         err = -EINVAL;
 590                         goto lwt_failure;
 591                 }
 592                 err = lwtunnel_build_state(encap_type, encap, nhc->nhc_family,
 593                                            cfg, &lwtstate, extack);
 594                 if (err)
 595                         goto lwt_failure;
 596
 597                 nhc->nhc_lwtstate = lwtstate_get(lwtstate);
 598         }
 599
 600         return 0;
 601
 602 lwt_failure:
 603         rt_fibinfo_free_cpus(nhc->nhc_pcpu_rth_output);
 604         nhc->nhc_pcpu_rth_output = NULL;
 605         return err;
 606 }
 607 EXPORT_SYMBOL_GPL(fib_nh_common_init);
 608
 609 int fib_nh_init(struct net *net, struct fib_nh *nh,
 610                 struct fib_config *cfg, int nh_weight,
 611                 struct netlink_ext_ack *extack)
 612 {
 613         int err;
 614
 615         nh->fib_nh_family = AF_INET;
 616
 617         err = fib_nh_common_init(&nh->nh_common, cfg->fc_encap,
 618                                  cfg->fc_encap_type, cfg, GFP_KERNEL, extack);
 619         if (err)
 620                 return err;
 621
 622         nh->fib_nh_oif = cfg->fc_oif;
 623         nh->fib_nh_gw_family = cfg->fc_gw_family;
 624         if (cfg->fc_gw_family == AF_INET)
 625                 nh->fib_nh_gw4 = cfg->fc_gw4;
 626         else if (cfg->fc_gw_family == AF_INET6)
 627                 nh->fib_nh_gw6 = cfg->fc_gw6;
 628
 629         nh->fib_nh_flags = cfg->fc_flags;
 630
 631 #ifdef CONFIG_IP_ROUTE_CLASSID
 632         nh->nh_tclassid = cfg->fc_flow;
 633         if (nh->nh_tclassid)
 634                 atomic_inc(&net->ipv4.fib_num_tclassid_users);
 635 #endif
 636 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 637         nh->fib_nh_weight = nh_weight;
 638 #endif
 639         return 0;
 640 }
 641
 642 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 643
 644 static int fib_count_nexthops(struct rtnexthop *rtnh, int remaining,
 645                               struct netlink_ext_ack *extack)
 646 {
 647         int nhs = 0;
 648
 649         while (rtnh_ok(rtnh, remaining)) {
 650                 nhs++;
 651                 rtnh = rtnh_next(rtnh, &remaining);
 652         }
 653
 654         /* leftover implies invalid nexthop configuration, discard it */
 655         if (remaining > 0) {
 656                 NL_SET_ERR_MSG(extack,
 657                                "Invalid nexthop configuration - extra data after nexthops");
 658                 nhs = 0;
 659         }
 660
 661         return nhs;
 662 }
 663
 664 static int fib_gw_from_attr(__be32 *gw, struct nlattr *nla,
 665                             struct netlink_ext_ack *extack)
 666 {
 667         if (nla_len(nla) < sizeof(*gw)) {
 668                 NL_SET_ERR_MSG(extack, "Invalid IPv4 address in RTA_GATEWAY");
 669                 return -EINVAL;
 670         }
 671
 672         *gw = nla_get_in_addr(nla);
 673
 674         return 0;
 675 }
 676
 677 /* only called when fib_nh is integrated into fib_info */
 678 static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh,
 679                        int remaining, struct fib_config *cfg,
 680                        struct netlink_ext_ack *extack)
 681 {
 682         struct net *net = fi->fib_net;
 683         struct fib_config fib_cfg;
 684         struct fib_nh *nh;
 685         int ret;
 686
 687         change_nexthops(fi) {
 688                 int attrlen;
 689
 690                 memset(&fib_cfg, 0, sizeof(fib_cfg));
 691
 692                 if (!rtnh_ok(rtnh, remaining)) {
 693                         NL_SET_ERR_MSG(extack,
 694                                        "Invalid nexthop configuration - extra data after nexthop");
 695                         return -EINVAL;
 696                 }
 697
 698                 if (rtnh->rtnh_flags & (RTNH_F_DEAD | RTNH_F_LINKDOWN)) {
 699                         NL_SET_ERR_MSG(extack,
 700                                        "Invalid flags for nexthop - can not contain DEAD or LINKDOWN");
 701                         return -EINVAL;
 702                 }
 703
 704                 fib_cfg.fc_flags = (cfg->fc_flags & ~0xFF) | rtnh->rtnh_flags;
 705                 fib_cfg.fc_oif = rtnh->rtnh_ifindex;
 706
 707                 attrlen = rtnh_attrlen(rtnh);
 708                 if (attrlen > 0) {
 709                         struct nlattr *nla, *nlav, *attrs = rtnh_attrs(rtnh);
 710
 711                         nla = nla_find(attrs, attrlen, RTA_GATEWAY);
 712                         nlav = nla_find(attrs, attrlen, RTA_VIA);
 713                         if (nla && nlav) {
 714                                 NL_SET_ERR_MSG(extack,
 715                                                "Nexthop configuration can not contain both GATEWAY and VIA");
 716                                 return -EINVAL;
 717                         }
 718                         if (nla) {
 719                                 ret = fib_gw_from_attr(&fib_cfg.fc_gw4, nla,
 720                                                        extack);
 721                                 if (ret)
 722                                         goto errout;
 723
 724                                 if (fib_cfg.fc_gw4)
 725                                         fib_cfg.fc_gw_family = AF_INET;
 726                         } else if (nlav) {
 727                                 ret = fib_gw_from_via(&fib_cfg, nlav, extack);
 728                                 if (ret)
 729                                         goto errout;
 730                         }
 731
 732                         nla = nla_find(attrs, attrlen, RTA_FLOW);
 733                         if (nla) {
 734                                 if (nla_len(nla) < sizeof(u32)) {
 735                                         NL_SET_ERR_MSG(extack, "Invalid RTA_FLOW");
 736                                         return -EINVAL;
 737                                 }
 738                                 fib_cfg.fc_flow = nla_get_u32(nla);
 739                         }
 740
 741                         fib_cfg.fc_encap = nla_find(attrs, attrlen, RTA_ENCAP);
 742                         /* RTA_ENCAP_TYPE length checked in
 743                          * lwtunnel_valid_encap_type_attr
 744                          */
 745                         nla = nla_find(attrs, attrlen, RTA_ENCAP_TYPE);
 746                         if (nla)
 747                                 fib_cfg.fc_encap_type = nla_get_u16(nla);
 748                 }
 749
 750                 ret = fib_nh_init(net, nexthop_nh, &fib_cfg,
 751                                   rtnh->rtnh_hops + 1, extack);
 752                 if (ret)
 753                         goto errout;
 754
 755                 rtnh = rtnh_next(rtnh, &remaining);
 756         } endfor_nexthops(fi);
 757
 758         ret = -EINVAL;
 759         nh = fib_info_nh(fi, 0);
 760         if (cfg->fc_oif && nh->fib_nh_oif != cfg->fc_oif) {
 761                 NL_SET_ERR_MSG(extack,
 762                                "Nexthop device index does not match RTA_OIF");
 763                 goto errout;
 764         }
 765         if (cfg->fc_gw_family) {
 766                 if (cfg->fc_gw_family != nh->fib_nh_gw_family ||
 767                     (cfg->fc_gw_family == AF_INET &&
 768                      nh->fib_nh_gw4 != cfg->fc_gw4) ||
 769                     (cfg->fc_gw_family == AF_INET6 &&
 770                      ipv6_addr_cmp(&nh->fib_nh_gw6, &cfg->fc_gw6))) {
 771                         NL_SET_ERR_MSG(extack,
 772                                        "Nexthop gateway does not match RTA_GATEWAY or RTA_VIA");
 773                         goto errout;
 774                 }
 775         }
 776 #ifdef CONFIG_IP_ROUTE_CLASSID
 777         if (cfg->fc_flow && nh->nh_tclassid != cfg->fc_flow) {
 778                 NL_SET_ERR_MSG(extack,
 779                                "Nexthop class id does not match RTA_FLOW");
 780                 goto errout;
 781         }
 782 #endif
 783         ret = 0;
 784 errout:
 785         return ret;
 786 }
 787
 788 /* only called when fib_nh is integrated into fib_info */
 789 static void fib_rebalance(struct fib_info *fi)
 790 {
 791         int total;
 792         int w;
 793
 794         if (fib_info_num_path(fi) < 2)
 795                 return;
 796
 797         total = 0;
 798         for_nexthops(fi) {
 799                 if (nh->fib_nh_flags & RTNH_F_DEAD)
 800                         continue;
 801
 802                 if (ip_ignore_linkdown(nh->fib_nh_dev) &&
 803                     nh->fib_nh_flags & RTNH_F_LINKDOWN)
 804                         continue;
 805
 806                 total += nh->fib_nh_weight;
 807         } endfor_nexthops(fi);
 808
 809         w = 0;
 810         change_nexthops(fi) {
 811                 int upper_bound;
 812
 813                 if (nexthop_nh->fib_nh_flags & RTNH_F_DEAD) {
 814                         upper_bound = -1;
 815                 } else if (ip_ignore_linkdown(nexthop_nh->fib_nh_dev) &&
 816                            nexthop_nh->fib_nh_flags & RTNH_F_LINKDOWN) {
 817                         upper_bound = -1;
 818                 } else {
 819                         w += nexthop_nh->fib_nh_weight;
 820                         upper_bound = DIV_ROUND_CLOSEST_ULL((u64)w << 31,
 821                                                             total) - 1;
 822                 }
 823
 824                 atomic_set(&nexthop_nh->fib_nh_upper_bound, upper_bound);
 825         } endfor_nexthops(fi);
 826 }
 827 #else /* CONFIG_IP_ROUTE_MULTIPATH */
 828
 829 static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh,
 830                        int remaining, struct fib_config *cfg,
 831                        struct netlink_ext_ack *extack)
 832 {
 833         NL_SET_ERR_MSG(extack, "Multipath support not enabled in kernel");
 834
 835         return -EINVAL;
 836 }
 837
 838 #define fib_rebalance(fi) do { } while (0)
 839
 840 #endif /* CONFIG_IP_ROUTE_MULTIPATH */
 841
 842 static int fib_encap_match(u16 encap_type,
 843                            struct nlattr *encap,
 844                            const struct fib_nh *nh,
 845                            const struct fib_config *cfg,
 846                            struct netlink_ext_ack *extack)
 847 {
 848         struct lwtunnel_state *lwtstate;
 849         int ret, result = 0;
 850
 851         if (encap_type == LWTUNNEL_ENCAP_NONE)
 852                 return 0;
 853
 854         ret = lwtunnel_build_state(encap_type, encap, AF_INET,
 855                                    cfg, &lwtstate, extack);
 856         if (!ret) {
 857                 result = lwtunnel_cmp_encap(lwtstate, nh->fib_nh_lws);
 858                 lwtstate_free(lwtstate);
 859         }
 860
 861         return result;
 862 }
 863
 864 int fib_nh_match(struct fib_config *cfg, struct fib_info *fi,
 865                  struct netlink_ext_ack *extack)
 866 {
 867 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 868         struct rtnexthop *rtnh;
 869         int remaining;
 870 #endif
 871
 872         if (cfg->fc_priority && cfg->fc_priority != fi->fib_priority)
 873                 return 1;
 874
 875         if (cfg->fc_nh_id) {
 876                 if (fi->nh && cfg->fc_nh_id == fi->nh->id)
 877                         return 0;
 878                 return 1;
 879         }
 880
 881         if (fi->nh) {
 882                 if (cfg->fc_oif || cfg->fc_gw_family || cfg->fc_mp)
 883                         return 1;
 884                 return 0;
 885         }
 886
 887         if (cfg->fc_oif || cfg->fc_gw_family) {
 888                 struct fib_nh *nh;
 889
 890                 nh = fib_info_nh(fi, 0);
 891                 if (cfg->fc_encap) {
 892                         if (fib_encap_match(cfg->fc_encap_type, cfg->fc_encap,
 893                                             nh, cfg, extack))
 894                                 return 1;
 895                 }
 896 #ifdef CONFIG_IP_ROUTE_CLASSID
 897                 if (cfg->fc_flow &&
 898                     cfg->fc_flow != nh->nh_tclassid)
 899                         return 1;
 900 #endif
 901                 if ((cfg->fc_oif && cfg->fc_oif != nh->fib_nh_oif) ||
 902                     (cfg->fc_gw_family &&
 903                      cfg->fc_gw_family != nh->fib_nh_gw_family))
 904                         return 1;
 905
 906                 if (cfg->fc_gw_family == AF_INET &&
 907                     cfg->fc_gw4 != nh->fib_nh_gw4)
 908                         return 1;
 909
 910                 if (cfg->fc_gw_family == AF_INET6 &&
 911                     ipv6_addr_cmp(&cfg->fc_gw6, &nh->fib_nh_gw6))
 912                         return 1;
 913
 914                 return 0;
 915         }
 916
 917 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 918         if (!cfg->fc_mp)
 919                 return 0;
 920
 921         rtnh = cfg->fc_mp;
 922         remaining = cfg->fc_mp_len;
 923
 924         for_nexthops(fi) {
 925                 int attrlen;
 926
 927                 if (!rtnh_ok(rtnh, remaining))
 928                         return -EINVAL;
 929
 930                 if (rtnh->rtnh_ifindex && rtnh->rtnh_ifindex != nh->fib_nh_oif)
 931                         return 1;
 932
 933                 attrlen = rtnh_attrlen(rtnh);
 934                 if (attrlen > 0) {
 935                         struct nlattr *nla, *nlav, *attrs = rtnh_attrs(rtnh);
 936                         int err;
 937
 938                         nla = nla_find(attrs, attrlen, RTA_GATEWAY);
 939                         nlav = nla_find(attrs, attrlen, RTA_VIA);
 940                         if (nla && nlav) {
 941                                 NL_SET_ERR_MSG(extack,
 942                                                "Nexthop configuration can not contain both GATEWAY and VIA");
 943                                 return -EINVAL;
 944                         }
 945
 946                         if (nla) {
 947                                 __be32 gw;
 948
 949                                 err = fib_gw_from_attr(&gw, nla, extack);
 950                                 if (err)
 951                                         return err;
 952
 953                                 if (nh->fib_nh_gw_family != AF_INET ||
 954                                     gw != nh->fib_nh_gw4)
 955                                         return 1;
 956                         } else if (nlav) {
 957                                 struct fib_config cfg2;
 958
 959                                 err = fib_gw_from_via(&cfg2, nlav, extack);
 960                                 if (err)
 961                                         return err;
 962
 963                                 switch (nh->fib_nh_gw_family) {
 964                                 case AF_INET:
 965                                         if (cfg2.fc_gw_family != AF_INET ||
 966                                             cfg2.fc_gw4 != nh->fib_nh_gw4)
 967                                                 return 1;
 968                                         break;
 969                                 case AF_INET6:
 970                                         if (cfg2.fc_gw_family != AF_INET6 ||
 971                                             ipv6_addr_cmp(&cfg2.fc_gw6,
 972                                                           &nh->fib_nh_gw6))
 973                                                 return 1;
 974                                         break;
 975                                 }
 976                         }
 977
 978 #ifdef CONFIG_IP_ROUTE_CLASSID
 979                         nla = nla_find(attrs, attrlen, RTA_FLOW);
 980                         if (nla) {
 981                                 if (nla_len(nla) < sizeof(u32)) {
 982                                         NL_SET_ERR_MSG(extack, "Invalid RTA_FLOW");
 983                                         return -EINVAL;
 984                                 }
 985                                 if (nla_get_u32(nla) != nh->nh_tclassid)
 986                                         return 1;
 987                         }
 988 #endif
 989                 }
 990
 991                 rtnh = rtnh_next(rtnh, &remaining);
 992         } endfor_nexthops(fi);
 993 #endif
 994         return 0;
 995 }
 996
 997 bool fib_metrics_match(struct fib_config *cfg, struct fib_info *fi)
 998 {
 999         struct nlattr *nla;
1000         int remaining;
1001
1002         if (!cfg->fc_mx)
1003                 return true;
1004
1005         nla_for_each_attr(nla, cfg->fc_mx, cfg->fc_mx_len, remaining) {
1006                 int type = nla_type(nla);
1007                 u32 fi_val, val;
1008
1009                 if (!type)
1010                         continue;
1011                 if (type > RTAX_MAX)
1012                         return false;
1013
1014                 type = array_index_nospec(type, RTAX_MAX + 1);
1015                 if (type == RTAX_CC_ALGO) {
1016                         char tmp[TCP_CA_NAME_MAX];
1017                         bool ecn_ca = false;
1018
1019                         nla_strlcpy(tmp, nla, sizeof(tmp));
1020                         val = tcp_ca_get_key_by_name(fi->fib_net, tmp, &ecn_ca);
1021                 } else {
1022                         if (nla_len(nla) != sizeof(u32))
1023                                 return false;
1024                         val = nla_get_u32(nla);
1025                 }
1026
1027                 fi_val = fi->fib_metrics->metrics[type - 1];
1028                 if (type == RTAX_FEATURES)
1029                         fi_val &= ~DST_FEATURE_ECN_CA;
1030
1031                 if (fi_val != val)
1032                         return false;
1033         }
1034
1035         return true;
1036 }
1037
1038 static int fib_check_nh_v6_gw(struct net *net, struct fib_nh *nh,
1039                               u32 table, struct netlink_ext_ack *extack)
1040 {
1041         struct fib6_config cfg = {
1042                 .fc_table = table,
1043                 .fc_flags = nh->fib_nh_flags | RTF_GATEWAY,
1044                 .fc_ifindex = nh->fib_nh_oif,
1045                 .fc_gateway = nh->fib_nh_gw6,
1046         };
1047         struct fib6_nh fib6_nh = {};
1048         int err;
1049
1050         err = ipv6_stub->fib6_nh_init(net, &fib6_nh, &cfg, GFP_KERNEL, extack);
1051         if (!err) {
1052                 nh->fib_nh_dev = fib6_nh.fib_nh_dev;
1053                 dev_hold(nh->fib_nh_dev);
1054                 nh->fib_nh_oif = nh->fib_nh_dev->ifindex;
1055                 nh->fib_nh_scope = RT_SCOPE_LINK;
1056
1057                 ipv6_stub->fib6_nh_release(&fib6_nh);
1058         }
1059
1060         return err;
1061 }
1062
1063 /*
1064  * Picture
1065  * -------
1066  *
1067  * Semantics of nexthop is very messy by historical reasons.
1068  * We have to take into account, that:
1069  * a) gateway can be actually local interface address,
1070  *    so that gatewayed route is direct.
1071  * b) gateway must be on-link address, possibly
1072  *    described not by an ifaddr, but also by a direct route.
1073  * c) If both gateway and interface are specified, they should not
1074  *    contradict.
1075  * d) If we use tunnel routes, gateway could be not on-link.
1076  *
1077  * Attempt to reconcile all of these (alas, self-contradictory) conditions
1078  * results in pretty ugly and hairy code with obscure logic.
1079  *
1080  * I chose to generalized it instead, so that the size
1081  * of code does not increase practically, but it becomes
1082  * much more general.
1083  * Every prefix is assigned a "scope" value: "host" is local address,
1084  * "link" is direct route,
1085  * [ ... "site" ... "interior" ... ]
1086  * and "universe" is true gateway route with global meaning.
1087  *
1088  * Every prefix refers to a set of "nexthop"s (gw, oif),
1089  * where gw must have narrower scope. This recursion stops
1090  * when gw has LOCAL scope or if "nexthop" is declared ONLINK,
1091  * which means that gw is forced to be on link.
1092  *
1093  * Code is still hairy, but now it is apparently logically
1094  * consistent and very flexible. F.e. as by-product it allows
1095  * to co-exists in peace independent exterior and interior
1096  * routing processes.
1097  *
1098  * Normally it looks as following.
1099  *
1100  * {universe prefix}  -> (gw, oif) [scope link]
1101  *                |
1102  *                |-> {link prefix} -> (gw, oif) [scope local]
1103  *                                      |
1104  *                                      |-> {local prefix} (terminal node)
1105  */
1106 static int fib_check_nh_v4_gw(struct net *net, struct fib_nh *nh, u32 table,
1107                               u8 scope, struct netlink_ext_ack *extack)
1108 {
1109         struct net_device *dev;
1110         struct fib_result res;
1111         int err = 0;
1112
1113         if (nh->fib_nh_flags & RTNH_F_ONLINK) {
1114                 unsigned int addr_type;
1115
1116                 if (scope >= RT_SCOPE_LINK) {
1117                         NL_SET_ERR_MSG(extack, "Nexthop has invalid scope");
1118                         return -EINVAL;
1119                 }
1120                 dev = __dev_get_by_index(net, nh->fib_nh_oif);
1121                 if (!dev) {
1122                         NL_SET_ERR_MSG(extack, "Nexthop device required for onlink");
1123                         return -ENODEV;
1124                 }
1125                 if (!(dev->flags & IFF_UP)) {
1126                         NL_SET_ERR_MSG(extack, "Nexthop device is not up");
1127                         return -ENETDOWN;
1128                 }
1129                 addr_type = inet_addr_type_dev_table(net, dev, nh->fib_nh_gw4);
1130                 if (addr_type != RTN_UNICAST) {
1131                         NL_SET_ERR_MSG(extack, "Nexthop has invalid gateway");
1132                         return -EINVAL;
1133                 }
1134                 if (!netif_carrier_ok(dev))
1135                         nh->fib_nh_flags |= RTNH_F_LINKDOWN;
1136                 nh->fib_nh_dev = dev;
1137                 dev_hold(dev);
1138                 nh->fib_nh_scope = RT_SCOPE_LINK;
1139                 return 0;
1140         }
1141         rcu_read_lock();
1142         {
1143                 struct fib_table *tbl = NULL;
1144                 struct flowi4 fl4 = {
1145                         .daddr = nh->fib_nh_gw4,
1146                         .flowi4_scope = scope + 1,
1147                         .flowi4_oif = nh->fib_nh_oif,
1148                         .flowi4_iif = LOOPBACK_IFINDEX,
1149                 };
1150
1151                 /* It is not necessary, but requires a bit of thinking */
1152                 if (fl4.flowi4_scope < RT_SCOPE_LINK)
1153                         fl4.flowi4_scope = RT_SCOPE_LINK;
1154
1155                 if (table && table != RT_TABLE_MAIN)
1156                         tbl = fib_get_table(net, table);
1157
1158                 if (tbl)
1159                         err = fib_table_lookup(tbl, &fl4, &res,
1160                                                FIB_LOOKUP_IGNORE_LINKSTATE |
1161                                                FIB_LOOKUP_NOREF);
1162
1163                 /* on error or if no table given do full lookup. This
1164                  * is needed for example when nexthops are in the local
1165                  * table rather than the given table
1166                  */
1167                 if (!tbl || err) {
1168                         err = fib_lookup(net, &fl4, &res,
1169                                          FIB_LOOKUP_IGNORE_LINKSTATE);
1170                 }
1171
1172                 if (err) {
1173                         NL_SET_ERR_MSG(extack, "Nexthop has invalid gateway");
1174                         goto out;
1175                 }
1176         }
1177
1178         err = -EINVAL;
1179         if (res.type != RTN_UNICAST && res.type != RTN_LOCAL) {
1180                 NL_SET_ERR_MSG(extack, "Nexthop has invalid gateway");
1181                 goto out;
1182         }
1183         nh->fib_nh_scope = res.scope;
1184         nh->fib_nh_oif = FIB_RES_OIF(res);
1185         nh->fib_nh_dev = dev = FIB_RES_DEV(res);
1186         if (!dev) {
1187                 NL_SET_ERR_MSG(extack,
1188                                "No egress device for nexthop gateway");
1189                 goto out;
1190         }
1191         dev_hold(dev);
1192         if (!netif_carrier_ok(dev))
1193                 nh->fib_nh_flags |= RTNH_F_LINKDOWN;
1194         err = (dev->flags & IFF_UP) ? 0 : -ENETDOWN;
1195 out:
1196         rcu_read_unlock();
1197         return err;
1198 }
1199
1200 static int fib_check_nh_nongw(struct net *net, struct fib_nh *nh,
1201                               struct netlink_ext_ack *extack)
1202 {
1203         struct in_device *in_dev;
1204         int err;
1205
1206         if (nh->fib_nh_flags & (RTNH_F_PERVASIVE | RTNH_F_ONLINK)) {
1207                 NL_SET_ERR_MSG(extack,
1208                                "Invalid flags for nexthop - PERVASIVE and ONLINK can not be set");
1209                 return -EINVAL;
1210         }
1211
1212         rcu_read_lock();
1213
1214         err = -ENODEV;
1215         in_dev = inetdev_by_index(net, nh->fib_nh_oif);
1216         if (!in_dev)
1217                 goto out;
1218         err = -ENETDOWN;
1219         if (!(in_dev->dev->flags & IFF_UP)) {
1220                 NL_SET_ERR_MSG(extack, "Device for nexthop is not up");
1221                 goto out;
1222         }
1223
1224         nh->fib_nh_dev = in_dev->dev;
1225         dev_hold(nh->fib_nh_dev);
1226         nh->fib_nh_scope = RT_SCOPE_LINK;
1227         if (!netif_carrier_ok(nh->fib_nh_dev))
1228                 nh->fib_nh_flags |= RTNH_F_LINKDOWN;
1229         err = 0;
1230 out:
1231         rcu_read_unlock();
1232         return err;
1233 }
1234
1235 int fib_check_nh(struct net *net, struct fib_nh *nh, u32 table, u8 scope,
1236                  struct netlink_ext_ack *extack)
1237 {
1238         int err;
1239
1240         if (nh->fib_nh_gw_family == AF_INET)
1241                 err = fib_check_nh_v4_gw(net, nh, table, scope, extack);
1242         else if (nh->fib_nh_gw_family == AF_INET6)
1243                 err = fib_check_nh_v6_gw(net, nh, table, extack);
1244         else
1245                 err = fib_check_nh_nongw(net, nh, extack);
1246
1247         return err;
1248 }
1249
1250 static inline unsigned int fib_laddr_hashfn(__be32 val)
1251 {
1252         unsigned int mask = (fib_info_hash_size - 1);
1253
1254         return ((__force u32)val ^
1255                 ((__force u32)val >> 7) ^
1256                 ((__force u32)val >> 14)) & mask;
1257 }
1258
1259 static struct hlist_head *fib_info_hash_alloc(int bytes)
1260 {
1261         if (bytes <= PAGE_SIZE)
1262                 return kzalloc(bytes, GFP_KERNEL);
1263         else
1264                 return (struct hlist_head *)
1265                         __get_free_pages(GFP_KERNEL | __GFP_ZERO,
1266                                          get_order(bytes));
1267 }
1268
1269 static void fib_info_hash_free(struct hlist_head *hash, int bytes)
1270 {
1271         if (!hash)
1272                 return;
1273
1274         if (bytes <= PAGE_SIZE)
1275                 kfree(hash);
1276         else
1277                 free_pages((unsigned long) hash, get_order(bytes));
1278 }
1279
1280 static void fib_info_hash_move(struct hlist_head *new_info_hash,
1281                                struct hlist_head *new_laddrhash,
1282                                unsigned int new_size)
1283 {
1284         struct hlist_head *old_info_hash, *old_laddrhash;
1285         unsigned int old_size = fib_info_hash_size;
1286         unsigned int i, bytes;
1287
1288         spin_lock_bh(&fib_info_lock);
1289         old_info_hash = fib_info_hash;
1290         old_laddrhash = fib_info_laddrhash;
1291         fib_info_hash_size = new_size;
1292
1293         for (i = 0; i < old_size; i++) {
1294                 struct hlist_head *head = &fib_info_hash[i];
1295                 struct hlist_node *n;
1296                 struct fib_info *fi;
1297
1298                 hlist_for_each_entry_safe(fi, n, head, fib_hash) {
1299                         struct hlist_head *dest;
1300                         unsigned int new_hash;
1301
1302                         new_hash = fib_info_hashfn(fi);
1303                         dest = &new_info_hash[new_hash];
1304                         hlist_add_head(&fi->fib_hash, dest);
1305                 }
1306         }
1307         fib_info_hash = new_info_hash;
1308
1309         for (i = 0; i < old_size; i++) {
1310                 struct hlist_head *lhead = &fib_info_laddrhash[i];
1311                 struct hlist_node *n;
1312                 struct fib_info *fi;
1313
1314                 hlist_for_each_entry_safe(fi, n, lhead, fib_lhash) {
1315                         struct hlist_head *ldest;
1316                         unsigned int new_hash;
1317
1318                         new_hash = fib_laddr_hashfn(fi->fib_prefsrc);
1319                         ldest = &new_laddrhash[new_hash];
1320                         hlist_add_head(&fi->fib_lhash, ldest);
1321                 }
1322         }
1323         fib_info_laddrhash = new_laddrhash;
1324
1325         spin_unlock_bh(&fib_info_lock);
1326
1327         bytes = old_size * sizeof(struct hlist_head *);
1328         fib_info_hash_free(old_info_hash, bytes);
1329         fib_info_hash_free(old_laddrhash, bytes);
1330 }
1331
1332 __be32 fib_info_update_nhc_saddr(struct net *net, struct fib_nh_common *nhc,
1333                                  unsigned char scope)
1334 {
1335         struct fib_nh *nh;
1336
1337         if (nhc->nhc_family != AF_INET)
1338                 return inet_select_addr(nhc->nhc_dev, 0, scope);
1339
1340         nh = container_of(nhc, struct fib_nh, nh_common);
1341         nh->nh_saddr = inet_select_addr(nh->fib_nh_dev, nh->fib_nh_gw4, scope);
1342         nh->nh_saddr_genid = atomic_read(&net->ipv4.dev_addr_genid);
1343
1344         return nh->nh_saddr;
1345 }
1346
1347 __be32 fib_result_prefsrc(struct net *net, struct fib_result *res)
1348 {
1349         struct fib_nh_common *nhc = res->nhc;
1350
1351         if (res->fi->fib_prefsrc)
1352                 return res->fi->fib_prefsrc;
1353
1354         if (nhc->nhc_family == AF_INET) {
1355                 struct fib_nh *nh;
1356
1357                 nh = container_of(nhc, struct fib_nh, nh_common);
1358                 if (nh->nh_saddr_genid == atomic_read(&net->ipv4.dev_addr_genid))
1359                         return nh->nh_saddr;
1360         }
1361
1362         return fib_info_update_nhc_saddr(net, nhc, res->fi->fib_scope);
1363 }
1364
1365 static bool fib_valid_prefsrc(struct fib_config *cfg, __be32 fib_prefsrc)
1366 {
1367         if (cfg->fc_type != RTN_LOCAL || !cfg->fc_dst ||
1368             fib_prefsrc != cfg->fc_dst) {
1369                 u32 tb_id = cfg->fc_table;
1370                 int rc;
1371
1372                 if (tb_id == RT_TABLE_MAIN)
1373                         tb_id = RT_TABLE_LOCAL;
1374
1375                 rc = inet_addr_type_table(cfg->fc_nlinfo.nl_net,
1376                                           fib_prefsrc, tb_id);
1377
1378                 if (rc != RTN_LOCAL && tb_id != RT_TABLE_LOCAL) {
1379                         rc = inet_addr_type_table(cfg->fc_nlinfo.nl_net,
1380                                                   fib_prefsrc, RT_TABLE_LOCAL);
1381                 }
1382
1383                 if (rc != RTN_LOCAL)
1384                         return false;
1385         }
1386         return true;
1387 }
1388
1389 struct fib_info *fib_create_info(struct fib_config *cfg,
1390                                  struct netlink_ext_ack *extack)
1391 {
1392         int err;
1393         struct fib_info *fi = NULL;
1394         struct nexthop *nh = NULL;
1395         struct fib_info *ofi;
1396         int nhs = 1;
1397         struct net *net = cfg->fc_nlinfo.nl_net;
1398
1399         if (cfg->fc_type > RTN_MAX)
1400                 goto err_inval;
1401
1402         /* Fast check to catch the most weird cases */
1403         if (fib_props[cfg->fc_type].scope > cfg->fc_scope) {
1404                 NL_SET_ERR_MSG(extack, "Invalid scope");
1405                 goto err_inval;
1406         }
1407
1408         if (cfg->fc_flags & (RTNH_F_DEAD | RTNH_F_LINKDOWN)) {
1409                 NL_SET_ERR_MSG(extack,
1410                                "Invalid rtm_flags - can not contain DEAD or LINKDOWN");
1411                 goto err_inval;
1412         }
1413
1414         if (cfg->fc_nh_id) {
1415                 if (!cfg->fc_mx) {
1416                         fi = fib_find_info_nh(net, cfg);
1417                         if (fi) {
1418                                 fi->fib_treeref++;
1419                                 return fi;
1420                         }
1421                 }
1422
1423                 nh = nexthop_find_by_id(net, cfg->fc_nh_id);
1424                 if (!nh) {
1425                         NL_SET_ERR_MSG(extack, "Nexthop id does not exist");
1426                         goto err_inval;
1427                 }
1428                 nhs = 0;
1429         }
1430
1431 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1432         if (cfg->fc_mp) {
1433                 nhs = fib_count_nexthops(cfg->fc_mp, cfg->fc_mp_len, extack);
1434                 if (nhs == 0)
1435                         goto err_inval;
1436         }
1437 #endif
1438
1439         err = -ENOBUFS;
1440         if (fib_info_cnt >= fib_info_hash_size) {
1441                 unsigned int new_size = fib_info_hash_size << 1;
1442                 struct hlist_head *new_info_hash;
1443                 struct hlist_head *new_laddrhash;
1444                 unsigned int bytes;
1445
1446                 if (!new_size)
1447                         new_size = 16;
1448                 bytes = new_size * sizeof(struct hlist_head *);
1449                 new_info_hash = fib_info_hash_alloc(bytes);
1450                 new_laddrhash = fib_info_hash_alloc(bytes);
1451                 if (!new_info_hash || !new_laddrhash) {
1452                         fib_info_hash_free(new_info_hash, bytes);
1453                         fib_info_hash_free(new_laddrhash, bytes);
1454                 } else
1455                         fib_info_hash_move(new_info_hash, new_laddrhash, new_size);
1456
1457                 if (!fib_info_hash_size)
1458                         goto failure;
1459         }
1460
1461         fi = kzalloc(struct_size(fi, fib_nh, nhs), GFP_KERNEL);
1462         if (!fi)
1463                 goto failure;
1464         fi->fib_metrics = ip_fib_metrics_init(fi->fib_net, cfg->fc_mx,
1465                                               cfg->fc_mx_len, extack);
1466         if (IS_ERR(fi->fib_metrics)) {
1467                 err = PTR_ERR(fi->fib_metrics);
1468                 kfree(fi);
1469                 return ERR_PTR(err);
1470         }
1471
1472         fib_info_cnt++;
1473         fi->fib_net = net;
1474         fi->fib_protocol = cfg->fc_protocol;
1475         fi->fib_scope = cfg->fc_scope;
1476         fi->fib_flags = cfg->fc_flags;
1477         fi->fib_priority = cfg->fc_priority;
1478         fi->fib_prefsrc = cfg->fc_prefsrc;
1479         fi->fib_type = cfg->fc_type;
1480         fi->fib_tb_id = cfg->fc_table;
1481
1482         fi->fib_nhs = nhs;
1483         if (nh) {
1484                 if (!nexthop_get(nh)) {
1485                         NL_SET_ERR_MSG(extack, "Nexthop has been deleted");
1486                         err = -EINVAL;
1487                 } else {
1488                         err = 0;
1489                         fi->nh = nh;
1490                 }
1491         } else {
1492                 change_nexthops(fi) {
1493                         nexthop_nh->nh_parent = fi;
1494                 } endfor_nexthops(fi)
1495
1496                 if (cfg->fc_mp)
1497                         err = fib_get_nhs(fi, cfg->fc_mp, cfg->fc_mp_len, cfg,
1498                                           extack);
1499                 else
1500                         err = fib_nh_init(net, fi->fib_nh, cfg, 1, extack);
1501         }
1502
1503         if (err != 0)
1504                 goto failure;
1505
1506         if (fib_props[cfg->fc_type].error) {
1507                 if (cfg->fc_gw_family || cfg->fc_oif || cfg->fc_mp) {
1508                         NL_SET_ERR_MSG(extack,
1509                                        "Gateway, device and multipath can not be specified for this route type");
1510                         goto err_inval;
1511                 }
1512                 goto link_it;
1513         } else {
1514                 switch (cfg->fc_type) {
1515                 case RTN_UNICAST:
1516                 case RTN_LOCAL:
1517                 case RTN_BROADCAST:
1518                 case RTN_ANYCAST:
1519                 case RTN_MULTICAST:
1520                         break;
1521                 default:
1522                         NL_SET_ERR_MSG(extack, "Invalid route type");
1523                         goto err_inval;
1524                 }
1525         }
1526
1527         if (cfg->fc_scope > RT_SCOPE_HOST) {
1528                 NL_SET_ERR_MSG(extack, "Invalid scope");
1529                 goto err_inval;
1530         }
1531
1532         if (fi->nh) {
1533                 err = fib_check_nexthop(fi->nh, cfg->fc_scope, extack);
1534                 if (err)
1535                         goto failure;
1536         } else if (cfg->fc_scope == RT_SCOPE_HOST) {
1537                 struct fib_nh *nh = fi->fib_nh;
1538
1539                 /* Local address is added. */
1540                 if (nhs != 1) {
1541                         NL_SET_ERR_MSG(extack,
1542                                        "Route with host scope can not have multiple nexthops");
1543                         goto err_inval;
1544                 }
1545                 if (nh->fib_nh_gw_family) {
1546                         NL_SET_ERR_MSG(extack,
1547                                        "Route with host scope can not have a gateway");
1548                         goto err_inval;
1549                 }
1550                 nh->fib_nh_scope = RT_SCOPE_NOWHERE;
1551                 nh->fib_nh_dev = dev_get_by_index(net, nh->fib_nh_oif);
1552                 err = -ENODEV;
1553                 if (!nh->fib_nh_dev)
1554                         goto failure;
1555         } else {
1556                 int linkdown = 0;
1557
1558                 change_nexthops(fi) {
1559                         err = fib_check_nh(cfg->fc_nlinfo.nl_net, nexthop_nh,
1560                                            cfg->fc_table, cfg->fc_scope,
1561                                            extack);
1562                         if (err != 0)
1563                                 goto failure;
1564                         if (nexthop_nh->fib_nh_flags & RTNH_F_LINKDOWN)
1565                                 linkdown++;
1566                 } endfor_nexthops(fi)
1567                 if (linkdown == fi->fib_nhs)
1568                         fi->fib_flags |= RTNH_F_LINKDOWN;
1569         }
1570
1571         if (fi->fib_prefsrc && !fib_valid_prefsrc(cfg, fi->fib_prefsrc)) {
1572                 NL_SET_ERR_MSG(extack, "Invalid prefsrc address");
1573                 goto err_inval;
1574         }
1575
1576         if (!fi->nh) {
1577                 change_nexthops(fi) {
1578                         fib_info_update_nhc_saddr(net, &nexthop_nh->nh_common,
1579                                                   fi->fib_scope);
1580                         if (nexthop_nh->fib_nh_gw_family == AF_INET6)
1581                                 fi->fib_nh_is_v6 = true;
1582                 } endfor_nexthops(fi)
1583
1584                 fib_rebalance(fi);
1585         }
1586
1587 link_it:
1588         ofi = fib_find_info(fi);
1589         if (ofi) {
1590                 /* fib_table_lookup() should not see @fi yet. */
1591                 fi->fib_dead = 1;
1592                 free_fib_info(fi);
1593                 ofi->fib_treeref++;
1594                 return ofi;
1595         }
1596
1597         fi->fib_treeref++;
1598         refcount_set(&fi->fib_clntref, 1);
1599         spin_lock_bh(&fib_info_lock);
1600         hlist_add_head(&fi->fib_hash,
1601                        &fib_info_hash[fib_info_hashfn(fi)]);
1602         if (fi->fib_prefsrc) {
1603                 struct hlist_head *head;
1604
1605                 head = &fib_info_laddrhash[fib_laddr_hashfn(fi->fib_prefsrc)];
1606                 hlist_add_head(&fi->fib_lhash, head);
1607         }
1608         if (fi->nh) {
1609                 list_add(&fi->nh_list, &nh->fi_list);
1610         } else {
1611                 change_nexthops(fi) {
1612                         struct hlist_head *head;
1613
1614                         if (!nexthop_nh->fib_nh_dev)
1615                                 continue;
1616                         head = fib_info_devhash_bucket(nexthop_nh->fib_nh_dev);
1617                         hlist_add_head(&nexthop_nh->nh_hash, head);
1618                 } endfor_nexthops(fi)
1619         }
1620         spin_unlock_bh(&fib_info_lock);
1621         return fi;
1622
1623 err_inval:
1624         err = -EINVAL;
1625
1626 failure:
1627         if (fi) {
1628                 /* fib_table_lookup() should not see @fi yet. */
1629                 fi->fib_dead = 1;
1630                 free_fib_info(fi);
1631         }
1632
1633         return ERR_PTR(err);
1634 }
1635
1636 int fib_nexthop_info(struct sk_buff *skb, const struct fib_nh_common *nhc,
1637                      u8 rt_family, unsigned char *flags, bool skip_oif)
1638 {
1639         if (nhc->nhc_flags & RTNH_F_DEAD)
1640                 *flags |= RTNH_F_DEAD;
1641
1642         if (nhc->nhc_flags & RTNH_F_LINKDOWN) {
1643                 *flags |= RTNH_F_LINKDOWN;
1644
1645                 rcu_read_lock();
1646                 switch (nhc->nhc_family) {
1647                 case AF_INET:
1648                         if (ip_ignore_linkdown(nhc->nhc_dev))
1649                                 *flags |= RTNH_F_DEAD;
1650                         break;
1651                 case AF_INET6:
1652                         if (ip6_ignore_linkdown(nhc->nhc_dev))
1653                                 *flags |= RTNH_F_DEAD;
1654                         break;
1655                 }
1656                 rcu_read_unlock();
1657         }
1658
1659         switch (nhc->nhc_gw_family) {
1660         case AF_INET:
1661                 if (nla_put_in_addr(skb, RTA_GATEWAY, nhc->nhc_gw.ipv4))
1662                         goto nla_put_failure;
1663                 break;
1664         case AF_INET6:
1665                 /* if gateway family does not match nexthop family
1666                  * gateway is encoded as RTA_VIA
1667                  */
1668                 if (rt_family != nhc->nhc_gw_family) {
1669                         int alen = sizeof(struct in6_addr);
1670                         struct nlattr *nla;
1671                         struct rtvia *via;
1672
1673                         nla = nla_reserve(skb, RTA_VIA, alen + 2);
1674                         if (!nla)
1675                                 goto nla_put_failure;
1676
1677                         via = nla_data(nla);
1678                         via->rtvia_family = AF_INET6;
1679                         memcpy(via->rtvia_addr, &nhc->nhc_gw.ipv6, alen);
1680                 } else if (nla_put_in6_addr(skb, RTA_GATEWAY,
1681                                             &nhc->nhc_gw.ipv6) < 0) {
1682                         goto nla_put_failure;
1683                 }
1684                 break;
1685         }
1686
1687         *flags |= (nhc->nhc_flags & RTNH_F_ONLINK);
1688         if (nhc->nhc_flags & RTNH_F_OFFLOAD)
1689                 *flags |= RTNH_F_OFFLOAD;
1690
1691         if (!skip_oif && nhc->nhc_dev &&
1692             nla_put_u32(skb, RTA_OIF, nhc->nhc_dev->ifindex))
1693                 goto nla_put_failure;
1694
1695         if (nhc->nhc_lwtstate &&
1696             lwtunnel_fill_encap(skb, nhc->nhc_lwtstate,
1697                                 RTA_ENCAP, RTA_ENCAP_TYPE) < 0)
1698                 goto nla_put_failure;
1699
1700         return 0;
1701
1702 nla_put_failure:
1703         return -EMSGSIZE;
1704 }
1705 EXPORT_SYMBOL_GPL(fib_nexthop_info);
1706
1707 #if IS_ENABLED(CONFIG_IP_ROUTE_MULTIPATH) || IS_ENABLED(CONFIG_IPV6)
1708 int fib_add_nexthop(struct sk_buff *skb, const struct fib_nh_common *nhc,
1709                     int nh_weight, u8 rt_family, u32 nh_tclassid)
1710 {
1711         const struct net_device *dev = nhc->nhc_dev;
1712         struct rtnexthop *rtnh;
1713         unsigned char flags = 0;
1714
1715         rtnh = nla_reserve_nohdr(skb, sizeof(*rtnh));
1716         if (!rtnh)
1717                 goto nla_put_failure;
1718
1719         rtnh->rtnh_hops = nh_weight - 1;
1720         rtnh->rtnh_ifindex = dev ? dev->ifindex : 0;
1721
1722         if (fib_nexthop_info(skb, nhc, rt_family, &flags, true) < 0)
1723                 goto nla_put_failure;
1724
1725         rtnh->rtnh_flags = flags;
1726
1727         if (nh_tclassid && nla_put_u32(skb, RTA_FLOW, nh_tclassid))
1728                 goto nla_put_failure;
1729
1730         /* length of rtnetlink header + attributes */
1731         rtnh->rtnh_len = nlmsg_get_pos(skb) - (void *)rtnh;
1732
1733         return 0;
1734
1735 nla_put_failure:
1736         return -EMSGSIZE;
1737 }
1738 EXPORT_SYMBOL_GPL(fib_add_nexthop);
1739 #endif
1740
1741 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1742 static int fib_add_multipath(struct sk_buff *skb, struct fib_info *fi)
1743 {
1744         struct nlattr *mp;
1745
1746         mp = nla_nest_start_noflag(skb, RTA_MULTIPATH);
1747         if (!mp)
1748                 goto nla_put_failure;
1749
1750         if (unlikely(fi->nh)) {
1751                 if (nexthop_mpath_fill_node(skb, fi->nh, AF_INET) < 0)
1752                         goto nla_put_failure;
1753                 goto mp_end;
1754         }
1755
1756         for_nexthops(fi) {
1757                 u32 nh_tclassid = 0;
1758 #ifdef CONFIG_IP_ROUTE_CLASSID
1759                 nh_tclassid = nh->nh_tclassid;
1760 #endif
1761                 if (fib_add_nexthop(skb, &nh->nh_common, nh->fib_nh_weight,
1762                                     AF_INET, nh_tclassid) < 0)
1763                         goto nla_put_failure;
1764         } endfor_nexthops(fi);
1765
1766 mp_end:
1767         nla_nest_end(skb, mp);
1768
1769         return 0;
1770
1771 nla_put_failure:
1772         return -EMSGSIZE;
1773 }
1774 #else
1775 static int fib_add_multipath(struct sk_buff *skb, struct fib_info *fi)
1776 {
1777         return 0;
1778 }
1779 #endif
1780
1781 int fib_dump_info(struct sk_buff *skb, u32 portid, u32 seq, int event,
1782                   u32 tb_id, u8 type, __be32 dst, int dst_len, u8 tos,
1783                   struct fib_info *fi, unsigned int flags)
1784 {
1785         unsigned int nhs = fib_info_num_path(fi);
1786         struct nlmsghdr *nlh;
1787         struct rtmsg *rtm;
1788
1789         nlh = nlmsg_put(skb, portid, seq, event, sizeof(*rtm), flags);
1790         if (!nlh)
1791                 return -EMSGSIZE;
1792
1793         rtm = nlmsg_data(nlh);
1794         rtm->rtm_family = AF_INET;
1795         rtm->rtm_dst_len = dst_len;
1796         rtm->rtm_src_len = 0;
1797         rtm->rtm_tos = tos;
1798         if (tb_id < 256)
1799                 rtm->rtm_table = tb_id;
1800         else
1801                 rtm->rtm_table = RT_TABLE_COMPAT;
1802         if (nla_put_u32(skb, RTA_TABLE, tb_id))
1803                 goto nla_put_failure;
1804         rtm->rtm_type = type;
1805         rtm->rtm_flags = fi->fib_flags;
1806         rtm->rtm_scope = fi->fib_scope;
1807         rtm->rtm_protocol = fi->fib_protocol;
1808
1809         if (rtm->rtm_dst_len &&
1810             nla_put_in_addr(skb, RTA_DST, dst))
1811                 goto nla_put_failure;
1812         if (fi->fib_priority &&
1813             nla_put_u32(skb, RTA_PRIORITY, fi->fib_priority))
1814                 goto nla_put_failure;
1815         if (rtnetlink_put_metrics(skb, fi->fib_metrics->metrics) < 0)
1816                 goto nla_put_failure;
1817
1818         if (fi->fib_prefsrc &&
1819             nla_put_in_addr(skb, RTA_PREFSRC, fi->fib_prefsrc))
1820                 goto nla_put_failure;
1821
1822         if (fi->nh) {
1823                 if (nla_put_u32(skb, RTA_NH_ID, fi->nh->id))
1824                         goto nla_put_failure;
1825                 if (nexthop_is_blackhole(fi->nh))
1826                         rtm->rtm_type = RTN_BLACKHOLE;
1827         }
1828
1829         if (nhs == 1) {
1830                 const struct fib_nh_common *nhc = fib_info_nhc(fi, 0);
1831                 unsigned char flags = 0;
1832
1833                 if (fib_nexthop_info(skb, nhc, AF_INET, &flags, false) < 0)
1834                         goto nla_put_failure;
1835
1836                 rtm->rtm_flags = flags;
1837 #ifdef CONFIG_IP_ROUTE_CLASSID
1838                 if (nhc->nhc_family == AF_INET) {
1839                         struct fib_nh *nh;
1840
1841                         nh = container_of(nhc, struct fib_nh, nh_common);
1842                         if (nh->nh_tclassid &&
1843                             nla_put_u32(skb, RTA_FLOW, nh->nh_tclassid))
1844                                 goto nla_put_failure;
1845                 }
1846 #endif
1847         } else {
1848                 if (fib_add_multipath(skb, fi) < 0)
1849                         goto nla_put_failure;
1850         }
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 ret = 0;
1869         unsigned int hash = fib_laddr_hashfn(local);
1870         struct hlist_head *head = &fib_info_laddrhash[hash];
1871         int tb_id = l3mdev_fib_table(dev) ? : RT_TABLE_MAIN;
1872         struct net *net = dev_net(dev);
1873         struct fib_info *fi;
1874
1875         if (!fib_info_laddrhash || local == 0)
1876                 return 0;
1877
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         default:
1912                 break;
1913         }
1914
1915         return NOTIFY_DONE;
1916 }
1917
1918 /* Update the PMTU of exceptions when:
1919  * - the new MTU of the first hop becomes smaller than the PMTU
1920  * - the old MTU was the same as the PMTU, and it limited discovery of
1921  *   larger MTUs on the path. With that limit raised, we can now
1922  *   discover larger MTUs
1923  * A special case is locked exceptions, for which the PMTU is smaller
1924  * than the minimal accepted PMTU:
1925  * - if the new MTU is greater than the PMTU, don't make any change
1926  * - otherwise, unlock and set PMTU
1927  */
1928 void fib_nhc_update_mtu(struct fib_nh_common *nhc, u32 new, u32 orig)
1929 {
1930         struct fnhe_hash_bucket *bucket;
1931         int i;
1932
1933         bucket = rcu_dereference_protected(nhc->nhc_exceptions, 1);
1934         if (!bucket)
1935                 return;
1936
1937         for (i = 0; i < FNHE_HASH_SIZE; i++) {
1938                 struct fib_nh_exception *fnhe;
1939
1940                 for (fnhe = rcu_dereference_protected(bucket[i].chain, 1);
1941                      fnhe;
1942                      fnhe = rcu_dereference_protected(fnhe->fnhe_next, 1)) {
1943                         if (fnhe->fnhe_mtu_locked) {
1944                                 if (new <= fnhe->fnhe_pmtu) {
1945                                         fnhe->fnhe_pmtu = new;
1946                                         fnhe->fnhe_mtu_locked = false;
1947                                 }
1948                         } else if (new < fnhe->fnhe_pmtu ||
1949                                    orig == fnhe->fnhe_pmtu) {
1950                                 fnhe->fnhe_pmtu = new;
1951                         }
1952                 }
1953         }
1954 }
1955
1956 void fib_sync_mtu(struct net_device *dev, u32 orig_mtu)
1957 {
1958         struct hlist_head *head = fib_info_devhash_bucket(dev);
1959         struct fib_nh *nh;
1960
1961         hlist_for_each_entry(nh, head, nh_hash) {
1962                 if (nh->fib_nh_dev == dev)
1963                         fib_nhc_update_mtu(&nh->nh_common, dev->mtu, orig_mtu);
1964         }
1965 }
1966
1967 /* Event              force Flags           Description
1968  * NETDEV_CHANGE      0     LINKDOWN        Carrier OFF, not for scope host
1969  * NETDEV_DOWN        0     LINKDOWN|DEAD   Link down, not for scope host
1970  * NETDEV_DOWN        1     LINKDOWN|DEAD   Last address removed
1971  * NETDEV_UNREGISTER  1     LINKDOWN|DEAD   Device removed
1972  *
1973  * only used when fib_nh is built into fib_info
1974  */
1975 int fib_sync_down_dev(struct net_device *dev, unsigned long event, bool force)
1976 {
1977         struct hlist_head *head = fib_info_devhash_bucket(dev);
1978         struct fib_info *prev_fi = NULL;
1979         int scope = RT_SCOPE_NOWHERE;
1980         struct fib_nh *nh;
1981         int ret = 0;
1982
1983         if (force)
1984                 scope = -1;
1985
1986         hlist_for_each_entry(nh, head, nh_hash) {
1987                 struct fib_info *fi = nh->nh_parent;
1988                 int dead;
1989
1990                 BUG_ON(!fi->fib_nhs);
1991                 if (nh->fib_nh_dev != dev || fi == prev_fi)
1992                         continue;
1993                 prev_fi = fi;
1994                 dead = 0;
1995                 change_nexthops(fi) {
1996                         if (nexthop_nh->fib_nh_flags & RTNH_F_DEAD)
1997                                 dead++;
1998                         else if (nexthop_nh->fib_nh_dev == dev &&
1999                                  nexthop_nh->fib_nh_scope != scope) {
2000                                 switch (event) {
2001                                 case NETDEV_DOWN:
2002                                 case NETDEV_UNREGISTER:
2003                                         nexthop_nh->fib_nh_flags |= RTNH_F_DEAD;
2004                                         /* fall through */
2005                                 case NETDEV_CHANGE:
2006                                         nexthop_nh->fib_nh_flags |= RTNH_F_LINKDOWN;
2007                                         break;
2008                                 }
2009                                 call_fib_nh_notifiers(nexthop_nh,
2010                                                       FIB_EVENT_NH_DEL);
2011                                 dead++;
2012                         }
2013 #ifdef CONFIG_IP_ROUTE_MULTIPATH
2014                         if (event == NETDEV_UNREGISTER &&
2015                             nexthop_nh->fib_nh_dev == dev) {
2016                                 dead = fi->fib_nhs;
2017                                 break;
2018                         }
2019 #endif
2020                 } endfor_nexthops(fi)
2021                 if (dead == fi->fib_nhs) {
2022                         switch (event) {
2023                         case NETDEV_DOWN:
2024                         case NETDEV_UNREGISTER:
2025                                 fi->fib_flags |= RTNH_F_DEAD;
2026                                 /* fall through */
2027                         case NETDEV_CHANGE:
2028                                 fi->fib_flags |= RTNH_F_LINKDOWN;
2029                                 break;
2030                         }
2031                         ret++;
2032                 }
2033
2034                 fib_rebalance(fi);
2035         }
2036
2037         return ret;
2038 }
2039
2040 /* Must be invoked inside of an RCU protected region.  */
2041 static void fib_select_default(const struct flowi4 *flp, struct fib_result *res)
2042 {
2043         struct fib_info *fi = NULL, *last_resort = NULL;
2044         struct hlist_head *fa_head = res->fa_head;
2045         struct fib_table *tb = res->table;
2046         u8 slen = 32 - res->prefixlen;
2047         int order = -1, last_idx = -1;
2048         struct fib_alias *fa, *fa1 = NULL;
2049         u32 last_prio = res->fi->fib_priority;
2050         u8 last_tos = 0;
2051
2052         hlist_for_each_entry_rcu(fa, fa_head, fa_list) {
2053                 struct fib_info *next_fi = fa->fa_info;
2054                 struct fib_nh_common *nhc;
2055
2056                 if (fa->fa_slen != slen)
2057                         continue;
2058                 if (fa->fa_tos && fa->fa_tos != flp->flowi4_tos)
2059                         continue;
2060                 if (fa->tb_id != tb->tb_id)
2061                         continue;
2062                 if (next_fi->fib_priority > last_prio &&
2063                     fa->fa_tos == last_tos) {
2064                         if (last_tos)
2065                                 continue;
2066                         break;
2067                 }
2068                 if (next_fi->fib_flags & RTNH_F_DEAD)
2069                         continue;
2070                 last_tos = fa->fa_tos;
2071                 last_prio = next_fi->fib_priority;
2072
2073                 if (next_fi->fib_scope != res->scope ||
2074                     fa->fa_type != RTN_UNICAST)
2075                         continue;
2076
2077                 nhc = fib_info_nhc(next_fi, 0);
2078                 if (!nhc->nhc_gw_family || nhc->nhc_scope != RT_SCOPE_LINK)
2079                         continue;
2080
2081                 fib_alias_accessed(fa);
2082
2083                 if (!fi) {
2084                         if (next_fi != res->fi)
2085                                 break;
2086                         fa1 = fa;
2087                 } else if (!fib_detect_death(fi, order, &last_resort,
2088                                              &last_idx, fa1->fa_default)) {
2089                         fib_result_assign(res, fi);
2090                         fa1->fa_default = order;
2091                         goto out;
2092                 }
2093                 fi = next_fi;
2094                 order++;
2095         }
2096
2097         if (order <= 0 || !fi) {
2098                 if (fa1)
2099                         fa1->fa_default = -1;
2100                 goto out;
2101         }
2102
2103         if (!fib_detect_death(fi, order, &last_resort, &last_idx,
2104                               fa1->fa_default)) {
2105                 fib_result_assign(res, fi);
2106                 fa1->fa_default = order;
2107                 goto out;
2108         }
2109
2110         if (last_idx >= 0)
2111                 fib_result_assign(res, last_resort);
2112         fa1->fa_default = last_idx;
2113 out:
2114         return;
2115 }
2116
2117 /*
2118  * Dead device goes up. We wake up dead nexthops.
2119  * It takes sense only on multipath routes.
2120  *
2121  * only used when fib_nh is built into fib_info
2122  */
2123 int fib_sync_up(struct net_device *dev, unsigned char nh_flags)
2124 {
2125         struct fib_info *prev_fi;
2126         struct hlist_head *head;
2127         struct fib_nh *nh;
2128         int ret;
2129
2130         if (!(dev->flags & IFF_UP))
2131                 return 0;
2132
2133         if (nh_flags & RTNH_F_DEAD) {
2134                 unsigned int flags = dev_get_flags(dev);
2135
2136                 if (flags & (IFF_RUNNING | IFF_LOWER_UP))
2137                         nh_flags |= RTNH_F_LINKDOWN;
2138         }
2139
2140         prev_fi = NULL;
2141         head = fib_info_devhash_bucket(dev);
2142         ret = 0;
2143
2144         hlist_for_each_entry(nh, head, nh_hash) {
2145                 struct fib_info *fi = nh->nh_parent;
2146                 int alive;
2147
2148                 BUG_ON(!fi->fib_nhs);
2149                 if (nh->fib_nh_dev != dev || fi == prev_fi)
2150                         continue;
2151
2152                 prev_fi = fi;
2153                 alive = 0;
2154                 change_nexthops(fi) {
2155                         if (!(nexthop_nh->fib_nh_flags & nh_flags)) {
2156                                 alive++;
2157                                 continue;
2158                         }
2159                         if (!nexthop_nh->fib_nh_dev ||
2160                             !(nexthop_nh->fib_nh_dev->flags & IFF_UP))
2161                                 continue;
2162                         if (nexthop_nh->fib_nh_dev != dev ||
2163                             !__in_dev_get_rtnl(dev))
2164                                 continue;
2165                         alive++;
2166                         nexthop_nh->fib_nh_flags &= ~nh_flags;
2167                         call_fib_nh_notifiers(nexthop_nh, FIB_EVENT_NH_ADD);
2168                 } endfor_nexthops(fi)
2169
2170                 if (alive > 0) {
2171                         fi->fib_flags &= ~nh_flags;
2172                         ret++;
2173                 }
2174
2175                 fib_rebalance(fi);
2176         }
2177
2178         return ret;
2179 }
2180
2181 #ifdef CONFIG_IP_ROUTE_MULTIPATH
2182 static bool fib_good_nh(const struct fib_nh *nh)
2183 {
2184         int state = NUD_REACHABLE;
2185
2186         if (nh->fib_nh_scope == RT_SCOPE_LINK) {
2187                 struct neighbour *n;
2188
2189                 rcu_read_lock_bh();
2190
2191                 if (likely(nh->fib_nh_gw_family == AF_INET))
2192                         n = __ipv4_neigh_lookup_noref(nh->fib_nh_dev,
2193                                                    (__force u32)nh->fib_nh_gw4);
2194                 else if (nh->fib_nh_gw_family == AF_INET6)
2195                         n = __ipv6_neigh_lookup_noref_stub(nh->fib_nh_dev,
2196                                                            &nh->fib_nh_gw6);
2197                 else
2198                         n = NULL;
2199                 if (n)
2200                         state = n->nud_state;
2201
2202                 rcu_read_unlock_bh();
2203         }
2204
2205         return !!(state & NUD_VALID);
2206 }
2207
2208 void fib_select_multipath(struct fib_result *res, int hash)
2209 {
2210         struct fib_info *fi = res->fi;
2211         struct net *net = fi->fib_net;
2212         bool first = false;
2213
2214         if (unlikely(res->fi->nh)) {
2215                 nexthop_path_fib_result(res, hash);
2216                 return;
2217         }
2218
2219         change_nexthops(fi) {
2220                 if (READ_ONCE(net->ipv4.sysctl_fib_multipath_use_neigh)) {
2221                         if (!fib_good_nh(nexthop_nh))
2222                                 continue;
2223                         if (!first) {
2224                                 res->nh_sel = nhsel;
2225                                 res->nhc = &nexthop_nh->nh_common;
2226                                 first = true;
2227                         }
2228                 }
2229
2230                 if (hash > atomic_read(&nexthop_nh->fib_nh_upper_bound))
2231                         continue;
2232
2233                 res->nh_sel = nhsel;
2234                 res->nhc = &nexthop_nh->nh_common;
2235                 return;
2236         } endfor_nexthops(fi);
2237 }
2238 #endif
2239
2240 void fib_select_path(struct net *net, struct fib_result *res,
2241                      struct flowi4 *fl4, const struct sk_buff *skb)
2242 {
2243         if (fl4->flowi4_oif && !(fl4->flowi4_flags & FLOWI_FLAG_SKIP_NH_OIF))
2244                 goto check_saddr;
2245
2246 #ifdef CONFIG_IP_ROUTE_MULTIPATH
2247         if (fib_info_num_path(res->fi) > 1) {
2248                 int h = fib_multipath_hash(net, fl4, skb, NULL);
2249
2250                 fib_select_multipath(res, h);
2251         }
2252         else
2253 #endif
2254         if (!res->prefixlen &&
2255             res->table->tb_num_default > 1 &&
2256             res->type == RTN_UNICAST)
2257                 fib_select_default(fl4, res);
2258
2259 check_saddr:
2260         if (!fl4->saddr)
2261                 fl4->saddr = fib_result_prefsrc(net, res);
2262 }