net/ipv4/route.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  *              ROUTE - implementation of the IP router.
   8  *
   9  * Authors:     Ross Biro
  10  *              Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
  11  *              Alan Cox, <gw4pts@gw4pts.ampr.org>
  12  *              Linus Torvalds, <Linus.Torvalds@helsinki.fi>
  13  *              Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
  14  *
  15  * Fixes:
  16  *              Alan Cox        :       Verify area fixes.
  17  *              Alan Cox        :       cli() protects routing changes
  18  *              Rui Oliveira    :       ICMP routing table updates
  19  *              (rco@di.uminho.pt)      Routing table insertion and update
  20  *              Linus Torvalds  :       Rewrote bits to be sensible
  21  *              Alan Cox        :       Added BSD route gw semantics
  22  *              Alan Cox        :       Super /proc >4K
  23  *              Alan Cox        :       MTU in route table
  24  *              Alan Cox        :       MSS actually. Also added the window
  25  *                                      clamper.
  26  *              Sam Lantinga    :       Fixed route matching in rt_del()
  27  *              Alan Cox        :       Routing cache support.
  28  *              Alan Cox        :       Removed compatibility cruft.
  29  *              Alan Cox        :       RTF_REJECT support.
  30  *              Alan Cox        :       TCP irtt support.
  31  *              Jonathan Naylor :       Added Metric support.
  32  *      Miquel van Smoorenburg  :       BSD API fixes.
  33  *      Miquel van Smoorenburg  :       Metrics.
  34  *              Alan Cox        :       Use __u32 properly
  35  *              Alan Cox        :       Aligned routing errors more closely with BSD
  36  *                                      our system is still very different.
  37  *              Alan Cox        :       Faster /proc handling
  38  *      Alexey Kuznetsov        :       Massive rework to support tree based routing,
  39  *                                      routing caches and better behaviour.
  40  *
  41  *              Olaf Erb        :       irtt wasn't being copied right.
  42  *              Bjorn Ekwall    :       Kerneld route support.
  43  *              Alan Cox        :       Multicast fixed (I hope)
  44  *              Pavel Krauz     :       Limited broadcast fixed
  45  *              Mike McLagan    :       Routing by source
  46  *      Alexey Kuznetsov        :       End of old history. Split to fib.c and
  47  *                                      route.c and rewritten from scratch.
  48  *              Andi Kleen      :       Load-limit warning messages.
  49  *      Vitaly E. Lavrov        :       Transparent proxy revived after year coma.
  50  *      Vitaly E. Lavrov        :       Race condition in ip_route_input_slow.
  51  *      Tobias Ringstrom        :       Uninitialized res.type in ip_route_output_slow.
  52  *      Vladimir V. Ivanov      :       IP rule info (flowid) is really useful.
  53  *              Marc Boucher    :       routing by fwmark
  54  *      Robert Olsson           :       Added rt_cache statistics
  55  *      Arnaldo C. Melo         :       Convert proc stuff to seq_file
  56  *      Eric Dumazet            :       hashed spinlocks and rt_check_expire() fixes.
  57  *      Ilia Sotnikov           :       Ignore TOS on PMTUD and Redirect
  58  *      Ilia Sotnikov           :       Removed TOS from hash calculations
  59  */
  60
  61 #define pr_fmt(fmt) "IPv4: " fmt
  62
  63 #include <linux/module.h>
  64 #include <linux/uaccess.h>
  65 #include <linux/bitops.h>
  66 #include <linux/types.h>
  67 #include <linux/kernel.h>
  68 #include <linux/mm.h>
  69 #include <linux/string.h>
  70 #include <linux/socket.h>
  71 #include <linux/sockios.h>
  72 #include <linux/errno.h>
  73 #include <linux/in.h>
  74 #include <linux/inet.h>
  75 #include <linux/netdevice.h>
  76 #include <linux/proc_fs.h>
  77 #include <linux/init.h>
  78 #include <linux/skbuff.h>
  79 #include <linux/inetdevice.h>
  80 #include <linux/igmp.h>
  81 #include <linux/pkt_sched.h>
  82 #include <linux/mroute.h>
  83 #include <linux/netfilter_ipv4.h>
  84 #include <linux/random.h>
  85 #include <linux/rcupdate.h>
  86 #include <linux/times.h>
  87 #include <linux/slab.h>
  88 #include <linux/jhash.h>
  89 #include <net/dst.h>
  90 #include <net/dst_metadata.h>
  91 #include <net/net_namespace.h>
  92 #include <net/protocol.h>
  93 #include <net/ip.h>
  94 #include <net/route.h>
  95 #include <net/inetpeer.h>
  96 #include <net/sock.h>
  97 #include <net/ip_fib.h>
  98 #include <net/nexthop.h>
  99 #include <net/arp.h>
 100 #include <net/tcp.h>
 101 #include <net/icmp.h>
 102 #include <net/xfrm.h>
 103 #include <net/lwtunnel.h>
 104 #include <net/netevent.h>
 105 #include <net/rtnetlink.h>
 106 #ifdef CONFIG_SYSCTL
 107 #include <linux/sysctl.h>
 108 #endif
 109 #include <net/secure_seq.h>
 110 #include <net/ip_tunnels.h>
 111 #include <net/l3mdev.h>
 112
 113 #include "fib_lookup.h"
 114
 115 #define RT_FL_TOS(oldflp4) \
 116         ((oldflp4)->flowi4_tos & (IPTOS_RT_MASK | RTO_ONLINK))
 117
 118 #define RT_GC_TIMEOUT (300*HZ)
 119
 120 static int ip_rt_max_size;
 121 static int ip_rt_redirect_number __read_mostly  = 9;
 122 static int ip_rt_redirect_load __read_mostly    = HZ / 50;
 123 static int ip_rt_redirect_silence __read_mostly = ((HZ / 50) << (9 + 1));
 124 static int ip_rt_error_cost __read_mostly       = HZ;
 125 static int ip_rt_error_burst __read_mostly      = 5 * HZ;
 126 static int ip_rt_mtu_expires __read_mostly      = 10 * 60 * HZ;
 127 static u32 ip_rt_min_pmtu __read_mostly         = 512 + 20 + 20;
 128 static int ip_rt_min_advmss __read_mostly       = 256;
 129
 130 static int ip_rt_gc_timeout __read_mostly       = RT_GC_TIMEOUT;
 131
 132 /*
 133  *      Interface to generic destination cache.
 134  */
 135
 136 static struct dst_entry *ipv4_dst_check(struct dst_entry *dst, u32 cookie);
 137 static unsigned int      ipv4_default_advmss(const struct dst_entry *dst);
 138 static unsigned int      ipv4_mtu(const struct dst_entry *dst);
 139 static struct dst_entry *ipv4_negative_advice(struct dst_entry *dst);
 140 static void              ipv4_link_failure(struct sk_buff *skb);
 141 static void              ip_rt_update_pmtu(struct dst_entry *dst, struct sock *sk,
 142                                            struct sk_buff *skb, u32 mtu);
 143 static void              ip_do_redirect(struct dst_entry *dst, struct sock *sk,
 144                                         struct sk_buff *skb);
 145 static void             ipv4_dst_destroy(struct dst_entry *dst);
 146
 147 static u32 *ipv4_cow_metrics(struct dst_entry *dst, unsigned long old)
 148 {
 149         WARN_ON(1);
 150         return NULL;
 151 }
 152
 153 static struct neighbour *ipv4_neigh_lookup(const struct dst_entry *dst,
 154                                            struct sk_buff *skb,
 155                                            const void *daddr);
 156 static void ipv4_confirm_neigh(const struct dst_entry *dst, const void *daddr);
 157
 158 static struct dst_ops ipv4_dst_ops = {
 159         .family =               AF_INET,
 160         .check =                ipv4_dst_check,
 161         .default_advmss =       ipv4_default_advmss,
 162         .mtu =                  ipv4_mtu,
 163         .cow_metrics =          ipv4_cow_metrics,
 164         .destroy =              ipv4_dst_destroy,
 165         .negative_advice =      ipv4_negative_advice,
 166         .link_failure =         ipv4_link_failure,
 167         .update_pmtu =          ip_rt_update_pmtu,
 168         .redirect =             ip_do_redirect,
 169         .local_out =            __ip_local_out,
 170         .neigh_lookup =         ipv4_neigh_lookup,
 171         .confirm_neigh =        ipv4_confirm_neigh,
 172 };
 173
 174 #define ECN_OR_COST(class)      TC_PRIO_##class
 175
 176 const __u8 ip_tos2prio[16] = {
 177         TC_PRIO_BESTEFFORT,
 178         ECN_OR_COST(BESTEFFORT),
 179         TC_PRIO_BESTEFFORT,
 180         ECN_OR_COST(BESTEFFORT),
 181         TC_PRIO_BULK,
 182         ECN_OR_COST(BULK),
 183         TC_PRIO_BULK,
 184         ECN_OR_COST(BULK),
 185         TC_PRIO_INTERACTIVE,
 186         ECN_OR_COST(INTERACTIVE),
 187         TC_PRIO_INTERACTIVE,
 188         ECN_OR_COST(INTERACTIVE),
 189         TC_PRIO_INTERACTIVE_BULK,
 190         ECN_OR_COST(INTERACTIVE_BULK),
 191         TC_PRIO_INTERACTIVE_BULK,
 192         ECN_OR_COST(INTERACTIVE_BULK)
 193 };
 194 EXPORT_SYMBOL(ip_tos2prio);
 195
 196 static DEFINE_PER_CPU(struct rt_cache_stat, rt_cache_stat);
 197 #define RT_CACHE_STAT_INC(field) raw_cpu_inc(rt_cache_stat.field)
 198
 199 #ifdef CONFIG_PROC_FS
 200 static void *rt_cache_seq_start(struct seq_file *seq, loff_t *pos)
 201 {
 202         if (*pos)
 203                 return NULL;
 204         return SEQ_START_TOKEN;
 205 }
 206
 207 static void *rt_cache_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 208 {
 209         ++*pos;
 210         return NULL;
 211 }
 212
 213 static void rt_cache_seq_stop(struct seq_file *seq, void *v)
 214 {
 215 }
 216
 217 static int rt_cache_seq_show(struct seq_file *seq, void *v)
 218 {
 219         if (v == SEQ_START_TOKEN)
 220                 seq_printf(seq, "%-127s\n",
 221                            "Iface\tDestination\tGateway \tFlags\t\tRefCnt\tUse\t"
 222                            "Metric\tSource\t\tMTU\tWindow\tIRTT\tTOS\tHHRef\t"
 223                            "HHUptod\tSpecDst");
 224         return 0;
 225 }
 226
 227 static const struct seq_operations rt_cache_seq_ops = {
 228         .start  = rt_cache_seq_start,
 229         .next   = rt_cache_seq_next,
 230         .stop   = rt_cache_seq_stop,
 231         .show   = rt_cache_seq_show,
 232 };
 233
 234 static int rt_cache_seq_open(struct inode *inode, struct file *file)
 235 {
 236         return seq_open(file, &rt_cache_seq_ops);
 237 }
 238
 239 static const struct file_operations rt_cache_seq_fops = {
 240         .open    = rt_cache_seq_open,
 241         .read    = seq_read,
 242         .llseek  = seq_lseek,
 243         .release = seq_release,
 244 };
 245
 246
 247 static void *rt_cpu_seq_start(struct seq_file *seq, loff_t *pos)
 248 {
 249         int cpu;
 250
 251         if (*pos == 0)
 252                 return SEQ_START_TOKEN;
 253
 254         for (cpu = *pos-1; cpu < nr_cpu_ids; ++cpu) {
 255                 if (!cpu_possible(cpu))
 256                         continue;
 257                 *pos = cpu+1;
 258                 return &per_cpu(rt_cache_stat, cpu);
 259         }
 260         return NULL;
 261 }
 262
 263 static void *rt_cpu_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 264 {
 265         int cpu;
 266
 267         for (cpu = *pos; cpu < nr_cpu_ids; ++cpu) {
 268                 if (!cpu_possible(cpu))
 269                         continue;
 270                 *pos = cpu+1;
 271                 return &per_cpu(rt_cache_stat, cpu);
 272         }
 273         return NULL;
 274
 275 }
 276
 277 static void rt_cpu_seq_stop(struct seq_file *seq, void *v)
 278 {
 279
 280 }
 281
 282 static int rt_cpu_seq_show(struct seq_file *seq, void *v)
 283 {
 284         struct rt_cache_stat *st = v;
 285
 286         if (v == SEQ_START_TOKEN) {
 287                 seq_printf(seq, "entries  in_hit in_slow_tot in_slow_mc in_no_route in_brd in_martian_dst in_martian_src  out_hit out_slow_tot out_slow_mc  gc_total gc_ignored gc_goal_miss gc_dst_overflow in_hlist_search out_hlist_search\n");
 288                 return 0;
 289         }
 290
 291         seq_printf(seq,"%08x  %08x %08x %08x %08x %08x %08x %08x "
 292                    " %08x %08x %08x %08x %08x %08x %08x %08x %08x \n",
 293                    dst_entries_get_slow(&ipv4_dst_ops),
 294                    0, /* st->in_hit */
 295                    st->in_slow_tot,
 296                    st->in_slow_mc,
 297                    st->in_no_route,
 298                    st->in_brd,
 299                    st->in_martian_dst,
 300                    st->in_martian_src,
 301
 302                    0, /* st->out_hit */
 303                    st->out_slow_tot,
 304                    st->out_slow_mc,
 305
 306                    0, /* st->gc_total */
 307                    0, /* st->gc_ignored */
 308                    0, /* st->gc_goal_miss */
 309                    0, /* st->gc_dst_overflow */
 310                    0, /* st->in_hlist_search */
 311                    0  /* st->out_hlist_search */
 312                 );
 313         return 0;
 314 }
 315
 316 static const struct seq_operations rt_cpu_seq_ops = {
 317         .start  = rt_cpu_seq_start,
 318         .next   = rt_cpu_seq_next,
 319         .stop   = rt_cpu_seq_stop,
 320         .show   = rt_cpu_seq_show,
 321 };
 322
 323
 324 static int rt_cpu_seq_open(struct inode *inode, struct file *file)
 325 {
 326         return seq_open(file, &rt_cpu_seq_ops);
 327 }
 328
 329 static const struct file_operations rt_cpu_seq_fops = {
 330         .open    = rt_cpu_seq_open,
 331         .read    = seq_read,
 332         .llseek  = seq_lseek,
 333         .release = seq_release,
 334 };
 335
 336 #ifdef CONFIG_IP_ROUTE_CLASSID
 337 static int rt_acct_proc_show(struct seq_file *m, void *v)
 338 {
 339         struct ip_rt_acct *dst, *src;
 340         unsigned int i, j;
 341
 342         dst = kcalloc(256, sizeof(struct ip_rt_acct), GFP_KERNEL);
 343         if (!dst)
 344                 return -ENOMEM;
 345
 346         for_each_possible_cpu(i) {
 347                 src = (struct ip_rt_acct *)per_cpu_ptr(ip_rt_acct, i);
 348                 for (j = 0; j < 256; j++) {
 349                         dst[j].o_bytes   += src[j].o_bytes;
 350                         dst[j].o_packets += src[j].o_packets;
 351                         dst[j].i_bytes   += src[j].i_bytes;
 352                         dst[j].i_packets += src[j].i_packets;
 353                 }
 354         }
 355
 356         seq_write(m, dst, 256 * sizeof(struct ip_rt_acct));
 357         kfree(dst);
 358         return 0;
 359 }
 360 #endif
 361
 362 static int __net_init ip_rt_do_proc_init(struct net *net)
 363 {
 364         struct proc_dir_entry *pde;
 365
 366         pde = proc_create("rt_cache", 0444, net->proc_net,
 367                           &rt_cache_seq_fops);
 368         if (!pde)
 369                 goto err1;
 370
 371         pde = proc_create("rt_cache", 0444,
 372                           net->proc_net_stat, &rt_cpu_seq_fops);
 373         if (!pde)
 374                 goto err2;
 375
 376 #ifdef CONFIG_IP_ROUTE_CLASSID
 377         pde = proc_create_single("rt_acct", 0, net->proc_net,
 378                         rt_acct_proc_show);
 379         if (!pde)
 380                 goto err3;
 381 #endif
 382         return 0;
 383
 384 #ifdef CONFIG_IP_ROUTE_CLASSID
 385 err3:
 386         remove_proc_entry("rt_cache", net->proc_net_stat);
 387 #endif
 388 err2:
 389         remove_proc_entry("rt_cache", net->proc_net);
 390 err1:
 391         return -ENOMEM;
 392 }
 393
 394 static void __net_exit ip_rt_do_proc_exit(struct net *net)
 395 {
 396         remove_proc_entry("rt_cache", net->proc_net_stat);
 397         remove_proc_entry("rt_cache", net->proc_net);
 398 #ifdef CONFIG_IP_ROUTE_CLASSID
 399         remove_proc_entry("rt_acct", net->proc_net);
 400 #endif
 401 }
 402
 403 static struct pernet_operations ip_rt_proc_ops __net_initdata =  {
 404         .init = ip_rt_do_proc_init,
 405         .exit = ip_rt_do_proc_exit,
 406 };
 407
 408 static int __init ip_rt_proc_init(void)
 409 {
 410         return register_pernet_subsys(&ip_rt_proc_ops);
 411 }
 412
 413 #else
 414 static inline int ip_rt_proc_init(void)
 415 {
 416         return 0;
 417 }
 418 #endif /* CONFIG_PROC_FS */
 419
 420 static inline bool rt_is_expired(const struct rtable *rth)
 421 {
 422         return rth->rt_genid != rt_genid_ipv4(dev_net(rth->dst.dev));
 423 }
 424
 425 void rt_cache_flush(struct net *net)
 426 {
 427         rt_genid_bump_ipv4(net);
 428 }
 429
 430 static struct neighbour *ipv4_neigh_lookup(const struct dst_entry *dst,
 431                                            struct sk_buff *skb,
 432                                            const void *daddr)
 433 {
 434         const struct rtable *rt = container_of(dst, struct rtable, dst);
 435         struct net_device *dev = dst->dev;
 436         struct neighbour *n;
 437
 438         rcu_read_lock_bh();
 439
 440         if (likely(rt->rt_gw_family == AF_INET)) {
 441                 n = ip_neigh_gw4(dev, rt->rt_gw4);
 442         } else if (rt->rt_gw_family == AF_INET6) {
 443                 n = ip_neigh_gw6(dev, &rt->rt_gw6);
 444         } else {
 445                 __be32 pkey;
 446
 447                 pkey = skb ? ip_hdr(skb)->daddr : *((__be32 *) daddr);
 448                 n = ip_neigh_gw4(dev, pkey);
 449         }
 450
 451         if (n && !refcount_inc_not_zero(&n->refcnt))
 452                 n = NULL;
 453
 454         rcu_read_unlock_bh();
 455
 456         return n;
 457 }
 458
 459 static void ipv4_confirm_neigh(const struct dst_entry *dst, const void *daddr)
 460 {
 461         const struct rtable *rt = container_of(dst, struct rtable, dst);
 462         struct net_device *dev = dst->dev;
 463         const __be32 *pkey = daddr;
 464
 465         if (rt->rt_gw_family == AF_INET) {
 466                 pkey = (const __be32 *)&rt->rt_gw4;
 467         } else if (rt->rt_gw_family == AF_INET6) {
 468                 return __ipv6_confirm_neigh_stub(dev, &rt->rt_gw6);
 469         } else if (!daddr ||
 470                  (rt->rt_flags &
 471                   (RTCF_MULTICAST | RTCF_BROADCAST | RTCF_LOCAL))) {
 472                 return;
 473         }
 474         __ipv4_confirm_neigh(dev, *(__force u32 *)pkey);
 475 }
 476
 477 #define IP_IDENTS_SZ 2048u
 478
 479 static atomic_t *ip_idents __read_mostly;
 480 static u32 *ip_tstamps __read_mostly;
 481
 482 /* In order to protect privacy, we add a perturbation to identifiers
 483  * if one generator is seldom used. This makes hard for an attacker
 484  * to infer how many packets were sent between two points in time.
 485  */
 486 u32 ip_idents_reserve(u32 hash, int segs)
 487 {
 488         u32 *p_tstamp = ip_tstamps + hash % IP_IDENTS_SZ;
 489         atomic_t *p_id = ip_idents + hash % IP_IDENTS_SZ;
 490         u32 old = READ_ONCE(*p_tstamp);
 491         u32 now = (u32)jiffies;
 492         u32 new, delta = 0;
 493
 494         if (old != now && cmpxchg(p_tstamp, old, now) == old)
 495                 delta = prandom_u32_max(now - old);
 496
 497         /* Do not use atomic_add_return() as it makes UBSAN unhappy */
 498         do {
 499                 old = (u32)atomic_read(p_id);
 500                 new = old + delta + segs;
 501         } while (atomic_cmpxchg(p_id, old, new) != old);
 502
 503         return new - segs;
 504 }
 505 EXPORT_SYMBOL(ip_idents_reserve);
 506
 507 void __ip_select_ident(struct net *net, struct iphdr *iph, int segs)
 508 {
 509         u32 hash, id;
 510
 511         /* Note the following code is not safe, but this is okay. */
 512         if (unlikely(siphash_key_is_zero(&net->ipv4.ip_id_key)))
 513                 get_random_bytes(&net->ipv4.ip_id_key,
 514                                  sizeof(net->ipv4.ip_id_key));
 515
 516         hash = siphash_3u32((__force u32)iph->daddr,
 517                             (__force u32)iph->saddr,
 518                             iph->protocol,
 519                             &net->ipv4.ip_id_key);
 520         id = ip_idents_reserve(hash, segs);
 521         iph->id = htons(id);
 522 }
 523 EXPORT_SYMBOL(__ip_select_ident);
 524
 525 static void __build_flow_key(const struct net *net, struct flowi4 *fl4,
 526                              const struct sock *sk,
 527                              const struct iphdr *iph,
 528                              int oif, u8 tos,
 529                              u8 prot, u32 mark, int flow_flags)
 530 {
 531         if (sk) {
 532                 const struct inet_sock *inet = inet_sk(sk);
 533
 534                 oif = sk->sk_bound_dev_if;
 535                 mark = sk->sk_mark;
 536                 tos = RT_CONN_FLAGS(sk);
 537                 prot = inet->hdrincl ? IPPROTO_RAW : sk->sk_protocol;
 538         }
 539         flowi4_init_output(fl4, oif, mark, tos,
 540                            RT_SCOPE_UNIVERSE, prot,
 541                            flow_flags,
 542                            iph->daddr, iph->saddr, 0, 0,
 543                            sock_net_uid(net, sk));
 544 }
 545
 546 static void build_skb_flow_key(struct flowi4 *fl4, const struct sk_buff *skb,
 547                                const struct sock *sk)
 548 {
 549         const struct net *net = dev_net(skb->dev);
 550         const struct iphdr *iph = ip_hdr(skb);
 551         int oif = skb->dev->ifindex;
 552         u8 tos = RT_TOS(iph->tos);
 553         u8 prot = iph->protocol;
 554         u32 mark = skb->mark;
 555
 556         __build_flow_key(net, fl4, sk, iph, oif, tos, prot, mark, 0);
 557 }
 558
 559 static void build_sk_flow_key(struct flowi4 *fl4, const struct sock *sk)
 560 {
 561         const struct inet_sock *inet = inet_sk(sk);
 562         const struct ip_options_rcu *inet_opt;
 563         __be32 daddr = inet->inet_daddr;
 564
 565         rcu_read_lock();
 566         inet_opt = rcu_dereference(inet->inet_opt);
 567         if (inet_opt && inet_opt->opt.srr)
 568                 daddr = inet_opt->opt.faddr;
 569         flowi4_init_output(fl4, sk->sk_bound_dev_if, sk->sk_mark,
 570                            RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE,
 571                            inet->hdrincl ? IPPROTO_RAW : sk->sk_protocol,
 572                            inet_sk_flowi_flags(sk),
 573                            daddr, inet->inet_saddr, 0, 0, sk->sk_uid);
 574         rcu_read_unlock();
 575 }
 576
 577 static void ip_rt_build_flow_key(struct flowi4 *fl4, const struct sock *sk,
 578                                  const struct sk_buff *skb)
 579 {
 580         if (skb)
 581                 build_skb_flow_key(fl4, skb, sk);
 582         else
 583                 build_sk_flow_key(fl4, sk);
 584 }
 585
 586 static DEFINE_SPINLOCK(fnhe_lock);
 587
 588 static void fnhe_flush_routes(struct fib_nh_exception *fnhe)
 589 {
 590         struct rtable *rt;
 591
 592         rt = rcu_dereference(fnhe->fnhe_rth_input);
 593         if (rt) {
 594                 RCU_INIT_POINTER(fnhe->fnhe_rth_input, NULL);
 595                 dst_dev_put(&rt->dst);
 596                 dst_release(&rt->dst);
 597         }
 598         rt = rcu_dereference(fnhe->fnhe_rth_output);
 599         if (rt) {
 600                 RCU_INIT_POINTER(fnhe->fnhe_rth_output, NULL);
 601                 dst_dev_put(&rt->dst);
 602                 dst_release(&rt->dst);
 603         }
 604 }
 605
 606 static struct fib_nh_exception *fnhe_oldest(struct fnhe_hash_bucket *hash)
 607 {
 608         struct fib_nh_exception *fnhe, *oldest;
 609
 610         oldest = rcu_dereference(hash->chain);
 611         for (fnhe = rcu_dereference(oldest->fnhe_next); fnhe;
 612              fnhe = rcu_dereference(fnhe->fnhe_next)) {
 613                 if (time_before(fnhe->fnhe_stamp, oldest->fnhe_stamp))
 614                         oldest = fnhe;
 615         }
 616         fnhe_flush_routes(oldest);
 617         return oldest;
 618 }
 619
 620 static inline u32 fnhe_hashfun(__be32 daddr)
 621 {
 622         static u32 fnhe_hashrnd __read_mostly;
 623         u32 hval;
 624
 625         net_get_random_once(&fnhe_hashrnd, sizeof(fnhe_hashrnd));
 626         hval = jhash_1word((__force u32) daddr, fnhe_hashrnd);
 627         return hash_32(hval, FNHE_HASH_SHIFT);
 628 }
 629
 630 static void fill_route_from_fnhe(struct rtable *rt, struct fib_nh_exception *fnhe)
 631 {
 632         rt->rt_pmtu = fnhe->fnhe_pmtu;
 633         rt->rt_mtu_locked = fnhe->fnhe_mtu_locked;
 634         rt->dst.expires = fnhe->fnhe_expires;
 635
 636         if (fnhe->fnhe_gw) {
 637                 rt->rt_flags |= RTCF_REDIRECTED;
 638                 rt->rt_gw_family = AF_INET;
 639                 rt->rt_gw4 = fnhe->fnhe_gw;
 640         }
 641 }
 642
 643 static void update_or_create_fnhe(struct fib_nh_common *nhc, __be32 daddr,
 644                                   __be32 gw, u32 pmtu, bool lock,
 645                                   unsigned long expires)
 646 {
 647         struct fnhe_hash_bucket *hash;
 648         struct fib_nh_exception *fnhe;
 649         struct rtable *rt;
 650         u32 genid, hval;
 651         unsigned int i;
 652         int depth;
 653
 654         genid = fnhe_genid(dev_net(nhc->nhc_dev));
 655         hval = fnhe_hashfun(daddr);
 656
 657         spin_lock_bh(&fnhe_lock);
 658
 659         hash = rcu_dereference(nhc->nhc_exceptions);
 660         if (!hash) {
 661                 hash = kcalloc(FNHE_HASH_SIZE, sizeof(*hash), GFP_ATOMIC);
 662                 if (!hash)
 663                         goto out_unlock;
 664                 rcu_assign_pointer(nhc->nhc_exceptions, hash);
 665         }
 666
 667         hash += hval;
 668
 669         depth = 0;
 670         for (fnhe = rcu_dereference(hash->chain); fnhe;
 671              fnhe = rcu_dereference(fnhe->fnhe_next)) {
 672                 if (fnhe->fnhe_daddr == daddr)
 673                         break;
 674                 depth++;
 675         }
 676
 677         if (fnhe) {
 678                 if (fnhe->fnhe_genid != genid)
 679                         fnhe->fnhe_genid = genid;
 680                 if (gw)
 681                         fnhe->fnhe_gw = gw;
 682                 if (pmtu) {
 683                         fnhe->fnhe_pmtu = pmtu;
 684                         fnhe->fnhe_mtu_locked = lock;
 685                 }
 686                 fnhe->fnhe_expires = max(1UL, expires);
 687                 /* Update all cached dsts too */
 688                 rt = rcu_dereference(fnhe->fnhe_rth_input);
 689                 if (rt)
 690                         fill_route_from_fnhe(rt, fnhe);
 691                 rt = rcu_dereference(fnhe->fnhe_rth_output);
 692                 if (rt)
 693                         fill_route_from_fnhe(rt, fnhe);
 694         } else {
 695                 if (depth > FNHE_RECLAIM_DEPTH)
 696                         fnhe = fnhe_oldest(hash);
 697                 else {
 698                         fnhe = kzalloc(sizeof(*fnhe), GFP_ATOMIC);
 699                         if (!fnhe)
 700                                 goto out_unlock;
 701
 702                         fnhe->fnhe_next = hash->chain;
 703                         rcu_assign_pointer(hash->chain, fnhe);
 704                 }
 705                 fnhe->fnhe_genid = genid;
 706                 fnhe->fnhe_daddr = daddr;
 707                 fnhe->fnhe_gw = gw;
 708                 fnhe->fnhe_pmtu = pmtu;
 709                 fnhe->fnhe_mtu_locked = lock;
 710                 fnhe->fnhe_expires = max(1UL, expires);
 711
 712                 /* Exception created; mark the cached routes for the nexthop
 713                  * stale, so anyone caching it rechecks if this exception
 714                  * applies to them.
 715                  */
 716                 rt = rcu_dereference(nhc->nhc_rth_input);
 717                 if (rt)
 718                         rt->dst.obsolete = DST_OBSOLETE_KILL;
 719
 720                 for_each_possible_cpu(i) {
 721                         struct rtable __rcu **prt;
 722                         prt = per_cpu_ptr(nhc->nhc_pcpu_rth_output, i);
 723                         rt = rcu_dereference(*prt);
 724                         if (rt)
 725                                 rt->dst.obsolete = DST_OBSOLETE_KILL;
 726                 }
 727         }
 728
 729         fnhe->fnhe_stamp = jiffies;
 730
 731 out_unlock:
 732         spin_unlock_bh(&fnhe_lock);
 733 }
 734
 735 static void __ip_do_redirect(struct rtable *rt, struct sk_buff *skb, struct flowi4 *fl4,
 736                              bool kill_route)
 737 {
 738         __be32 new_gw = icmp_hdr(skb)->un.gateway;
 739         __be32 old_gw = ip_hdr(skb)->saddr;
 740         struct net_device *dev = skb->dev;
 741         struct in_device *in_dev;
 742         struct fib_result res;
 743         struct neighbour *n;
 744         struct net *net;
 745
 746         switch (icmp_hdr(skb)->code & 7) {
 747         case ICMP_REDIR_NET:
 748         case ICMP_REDIR_NETTOS:
 749         case ICMP_REDIR_HOST:
 750         case ICMP_REDIR_HOSTTOS:
 751                 break;
 752
 753         default:
 754                 return;
 755         }
 756
 757         if (rt->rt_gw_family != AF_INET || rt->rt_gw4 != old_gw)
 758                 return;
 759
 760         in_dev = __in_dev_get_rcu(dev);
 761         if (!in_dev)
 762                 return;
 763
 764         net = dev_net(dev);
 765         if (new_gw == old_gw || !IN_DEV_RX_REDIRECTS(in_dev) ||
 766             ipv4_is_multicast(new_gw) || ipv4_is_lbcast(new_gw) ||
 767             ipv4_is_zeronet(new_gw))
 768                 goto reject_redirect;
 769
 770         if (!IN_DEV_SHARED_MEDIA(in_dev)) {
 771                 if (!inet_addr_onlink(in_dev, new_gw, old_gw))
 772                         goto reject_redirect;
 773                 if (IN_DEV_SEC_REDIRECTS(in_dev) && ip_fib_check_default(new_gw, dev))
 774                         goto reject_redirect;
 775         } else {
 776                 if (inet_addr_type(net, new_gw) != RTN_UNICAST)
 777                         goto reject_redirect;
 778         }
 779
 780         n = __ipv4_neigh_lookup(rt->dst.dev, new_gw);
 781         if (!n)
 782                 n = neigh_create(&arp_tbl, &new_gw, rt->dst.dev);
 783         if (!IS_ERR(n)) {
 784                 if (!(n->nud_state & NUD_VALID)) {
 785                         neigh_event_send(n, NULL);
 786                 } else {
 787                         if (fib_lookup(net, fl4, &res, 0) == 0) {
 788                                 struct fib_nh_common *nhc = FIB_RES_NHC(res);
 789
 790                                 update_or_create_fnhe(nhc, fl4->daddr, new_gw,
 791                                                 0, false,
 792                                                 jiffies + ip_rt_gc_timeout);
 793                         }
 794                         if (kill_route)
 795                                 rt->dst.obsolete = DST_OBSOLETE_KILL;
 796                         call_netevent_notifiers(NETEVENT_NEIGH_UPDATE, n);
 797                 }
 798                 neigh_release(n);
 799         }
 800         return;
 801
 802 reject_redirect:
 803 #ifdef CONFIG_IP_ROUTE_VERBOSE
 804         if (IN_DEV_LOG_MARTIANS(in_dev)) {
 805                 const struct iphdr *iph = (const struct iphdr *) skb->data;
 806                 __be32 daddr = iph->daddr;
 807                 __be32 saddr = iph->saddr;
 808
 809                 net_info_ratelimited("Redirect from %pI4 on %s about %pI4 ignored\n"
 810                                      "  Advised path = %pI4 -> %pI4\n",
 811                                      &old_gw, dev->name, &new_gw,
 812                                      &saddr, &daddr);
 813         }
 814 #endif
 815         ;
 816 }
 817
 818 static void ip_do_redirect(struct dst_entry *dst, struct sock *sk, struct sk_buff *skb)
 819 {
 820         struct rtable *rt;
 821         struct flowi4 fl4;
 822         const struct iphdr *iph = (const struct iphdr *) skb->data;
 823         struct net *net = dev_net(skb->dev);
 824         int oif = skb->dev->ifindex;
 825         u8 tos = RT_TOS(iph->tos);
 826         u8 prot = iph->protocol;
 827         u32 mark = skb->mark;
 828
 829         rt = (struct rtable *) dst;
 830
 831         __build_flow_key(net, &fl4, sk, iph, oif, tos, prot, mark, 0);
 832         __ip_do_redirect(rt, skb, &fl4, true);
 833 }
 834
 835 static struct dst_entry *ipv4_negative_advice(struct dst_entry *dst)
 836 {
 837         struct rtable *rt = (struct rtable *)dst;
 838         struct dst_entry *ret = dst;
 839
 840         if (rt) {
 841                 if (dst->obsolete > 0) {
 842                         ip_rt_put(rt);
 843                         ret = NULL;
 844                 } else if ((rt->rt_flags & RTCF_REDIRECTED) ||
 845                            rt->dst.expires) {
 846                         ip_rt_put(rt);
 847                         ret = NULL;
 848                 }
 849         }
 850         return ret;
 851 }
 852
 853 /*
 854  * Algorithm:
 855  *      1. The first ip_rt_redirect_number redirects are sent
 856  *         with exponential backoff, then we stop sending them at all,
 857  *         assuming that the host ignores our redirects.
 858  *      2. If we did not see packets requiring redirects
 859  *         during ip_rt_redirect_silence, we assume that the host
 860  *         forgot redirected route and start to send redirects again.
 861  *
 862  * This algorithm is much cheaper and more intelligent than dumb load limiting
 863  * in icmp.c.
 864  *
 865  * NOTE. Do not forget to inhibit load limiting for redirects (redundant)
 866  * and "frag. need" (breaks PMTU discovery) in icmp.c.
 867  */
 868
 869 void ip_rt_send_redirect(struct sk_buff *skb)
 870 {
 871         struct rtable *rt = skb_rtable(skb);
 872         struct in_device *in_dev;
 873         struct inet_peer *peer;
 874         struct net *net;
 875         int log_martians;
 876         int vif;
 877
 878         rcu_read_lock();
 879         in_dev = __in_dev_get_rcu(rt->dst.dev);
 880         if (!in_dev || !IN_DEV_TX_REDIRECTS(in_dev)) {
 881                 rcu_read_unlock();
 882                 return;
 883         }
 884         log_martians = IN_DEV_LOG_MARTIANS(in_dev);
 885         vif = l3mdev_master_ifindex_rcu(rt->dst.dev);
 886         rcu_read_unlock();
 887
 888         net = dev_net(rt->dst.dev);
 889         peer = inet_getpeer_v4(net->ipv4.peers, ip_hdr(skb)->saddr, vif, 1);
 890         if (!peer) {
 891                 icmp_send(skb, ICMP_REDIRECT, ICMP_REDIR_HOST,
 892                           rt_nexthop(rt, ip_hdr(skb)->daddr));
 893                 return;
 894         }
 895
 896         /* No redirected packets during ip_rt_redirect_silence;
 897          * reset the algorithm.
 898          */
 899         if (time_after(jiffies, peer->rate_last + ip_rt_redirect_silence)) {
 900                 peer->rate_tokens = 0;
 901                 peer->n_redirects = 0;
 902         }
 903
 904         /* Too many ignored redirects; do not send anything
 905          * set dst.rate_last to the last seen redirected packet.
 906          */
 907         if (peer->n_redirects >= ip_rt_redirect_number) {
 908                 peer->rate_last = jiffies;
 909                 goto out_put_peer;
 910         }
 911
 912         /* Check for load limit; set rate_last to the latest sent
 913          * redirect.
 914          */
 915         if (peer->rate_tokens == 0 ||
 916             time_after(jiffies,
 917                        (peer->rate_last +
 918                         (ip_rt_redirect_load << peer->rate_tokens)))) {
 919                 __be32 gw = rt_nexthop(rt, ip_hdr(skb)->daddr);
 920
 921                 icmp_send(skb, ICMP_REDIRECT, ICMP_REDIR_HOST, gw);
 922                 peer->rate_last = jiffies;
 923                 ++peer->rate_tokens;
 924                 ++peer->n_redirects;
 925 #ifdef CONFIG_IP_ROUTE_VERBOSE
 926                 if (log_martians &&
 927                     peer->rate_tokens == ip_rt_redirect_number)
 928                         net_warn_ratelimited("host %pI4/if%d ignores redirects for %pI4 to %pI4\n",
 929                                              &ip_hdr(skb)->saddr, inet_iif(skb),
 930                                              &ip_hdr(skb)->daddr, &gw);
 931 #endif
 932         }
 933 out_put_peer:
 934         inet_putpeer(peer);
 935 }
 936
 937 static int ip_error(struct sk_buff *skb)
 938 {
 939         struct rtable *rt = skb_rtable(skb);
 940         struct net_device *dev = skb->dev;
 941         struct in_device *in_dev;
 942         struct inet_peer *peer;
 943         unsigned long now;
 944         struct net *net;
 945         bool send;
 946         int code;
 947
 948         if (netif_is_l3_master(skb->dev)) {
 949                 dev = __dev_get_by_index(dev_net(skb->dev), IPCB(skb)->iif);
 950                 if (!dev)
 951                         goto out;
 952         }
 953
 954         in_dev = __in_dev_get_rcu(dev);
 955
 956         /* IP on this device is disabled. */
 957         if (!in_dev)
 958                 goto out;
 959
 960         net = dev_net(rt->dst.dev);
 961         if (!IN_DEV_FORWARD(in_dev)) {
 962                 switch (rt->dst.error) {
 963                 case EHOSTUNREACH:
 964                         __IP_INC_STATS(net, IPSTATS_MIB_INADDRERRORS);
 965                         break;
 966
 967                 case ENETUNREACH:
 968                         __IP_INC_STATS(net, IPSTATS_MIB_INNOROUTES);
 969                         break;
 970                 }
 971                 goto out;
 972         }
 973
 974         switch (rt->dst.error) {
 975         case EINVAL:
 976         default:
 977                 goto out;
 978         case EHOSTUNREACH:
 979                 code = ICMP_HOST_UNREACH;
 980                 break;
 981         case ENETUNREACH:
 982                 code = ICMP_NET_UNREACH;
 983                 __IP_INC_STATS(net, IPSTATS_MIB_INNOROUTES);
 984                 break;
 985         case EACCES:
 986                 code = ICMP_PKT_FILTERED;
 987                 break;
 988         }
 989
 990         peer = inet_getpeer_v4(net->ipv4.peers, ip_hdr(skb)->saddr,
 991                                l3mdev_master_ifindex(skb->dev), 1);
 992
 993         send = true;
 994         if (peer) {
 995                 now = jiffies;
 996                 peer->rate_tokens += now - peer->rate_last;
 997                 if (peer->rate_tokens > ip_rt_error_burst)
 998                         peer->rate_tokens = ip_rt_error_burst;
 999                 peer->rate_last = now;
1000                 if (peer->rate_tokens >= ip_rt_error_cost)
1001                         peer->rate_tokens -= ip_rt_error_cost;
1002                 else
1003                         send = false;
1004                 inet_putpeer(peer);
1005         }
1006         if (send)
1007                 icmp_send(skb, ICMP_DEST_UNREACH, code, 0);
1008
1009 out:    kfree_skb(skb);
1010         return 0;
1011 }
1012
1013 static void __ip_rt_update_pmtu(struct rtable *rt, struct flowi4 *fl4, u32 mtu)
1014 {
1015         struct dst_entry *dst = &rt->dst;
1016         u32 old_mtu = ipv4_mtu(dst);
1017         struct fib_result res;
1018         bool lock = false;
1019
1020         if (ip_mtu_locked(dst))
1021                 return;
1022
1023         if (old_mtu < mtu)
1024                 return;
1025
1026         if (mtu < ip_rt_min_pmtu) {
1027                 lock = true;
1028                 mtu = min(old_mtu, ip_rt_min_pmtu);
1029         }
1030
1031         if (rt->rt_pmtu == mtu && !lock &&
1032             time_before(jiffies, dst->expires - ip_rt_mtu_expires / 2))
1033                 return;
1034
1035         rcu_read_lock();
1036         if (fib_lookup(dev_net(dst->dev), fl4, &res, 0) == 0) {
1037                 struct fib_nh_common *nhc = FIB_RES_NHC(res);
1038
1039                 update_or_create_fnhe(nhc, fl4->daddr, 0, mtu, lock,
1040                                       jiffies + ip_rt_mtu_expires);
1041         }
1042         rcu_read_unlock();
1043 }
1044
1045 static void ip_rt_update_pmtu(struct dst_entry *dst, struct sock *sk,
1046                               struct sk_buff *skb, u32 mtu)
1047 {
1048         struct rtable *rt = (struct rtable *) dst;
1049         struct flowi4 fl4;
1050
1051         ip_rt_build_flow_key(&fl4, sk, skb);
1052         __ip_rt_update_pmtu(rt, &fl4, mtu);
1053 }
1054
1055 void ipv4_update_pmtu(struct sk_buff *skb, struct net *net, u32 mtu,
1056                       int oif, u8 protocol)
1057 {
1058         const struct iphdr *iph = (const struct iphdr *) skb->data;
1059         struct flowi4 fl4;
1060         struct rtable *rt;
1061         u32 mark = IP4_REPLY_MARK(net, skb->mark);
1062
1063         __build_flow_key(net, &fl4, NULL, iph, oif,
1064                          RT_TOS(iph->tos), protocol, mark, 0);
1065         rt = __ip_route_output_key(net, &fl4);
1066         if (!IS_ERR(rt)) {
1067                 __ip_rt_update_pmtu(rt, &fl4, mtu);
1068                 ip_rt_put(rt);
1069         }
1070 }
1071 EXPORT_SYMBOL_GPL(ipv4_update_pmtu);
1072
1073 static void __ipv4_sk_update_pmtu(struct sk_buff *skb, struct sock *sk, u32 mtu)
1074 {
1075         const struct iphdr *iph = (const struct iphdr *) skb->data;
1076         struct flowi4 fl4;
1077         struct rtable *rt;
1078
1079         __build_flow_key(sock_net(sk), &fl4, sk, iph, 0, 0, 0, 0, 0);
1080
1081         if (!fl4.flowi4_mark)
1082                 fl4.flowi4_mark = IP4_REPLY_MARK(sock_net(sk), skb->mark);
1083
1084         rt = __ip_route_output_key(sock_net(sk), &fl4);
1085         if (!IS_ERR(rt)) {
1086                 __ip_rt_update_pmtu(rt, &fl4, mtu);
1087                 ip_rt_put(rt);
1088         }
1089 }
1090
1091 void ipv4_sk_update_pmtu(struct sk_buff *skb, struct sock *sk, u32 mtu)
1092 {
1093         const struct iphdr *iph = (const struct iphdr *) skb->data;
1094         struct flowi4 fl4;
1095         struct rtable *rt;
1096         struct dst_entry *odst = NULL;
1097         bool new = false;
1098         struct net *net = sock_net(sk);
1099
1100         bh_lock_sock(sk);
1101
1102         if (!ip_sk_accept_pmtu(sk))
1103                 goto out;
1104
1105         odst = sk_dst_get(sk);
1106
1107         if (sock_owned_by_user(sk) || !odst) {
1108                 __ipv4_sk_update_pmtu(skb, sk, mtu);
1109                 goto out;
1110         }
1111
1112         __build_flow_key(net, &fl4, sk, iph, 0, 0, 0, 0, 0);
1113
1114         rt = (struct rtable *)odst;
1115         if (odst->obsolete && !odst->ops->check(odst, 0)) {
1116                 rt = ip_route_output_flow(sock_net(sk), &fl4, sk);
1117                 if (IS_ERR(rt))
1118                         goto out;
1119
1120                 new = true;
1121         }
1122
1123         __ip_rt_update_pmtu((struct rtable *) xfrm_dst_path(&rt->dst), &fl4, mtu);
1124
1125         if (!dst_check(&rt->dst, 0)) {
1126                 if (new)
1127                         dst_release(&rt->dst);
1128
1129                 rt = ip_route_output_flow(sock_net(sk), &fl4, sk);
1130                 if (IS_ERR(rt))
1131                         goto out;
1132
1133                 new = true;
1134         }
1135
1136         if (new)
1137                 sk_dst_set(sk, &rt->dst);
1138
1139 out:
1140         bh_unlock_sock(sk);
1141         dst_release(odst);
1142 }
1143 EXPORT_SYMBOL_GPL(ipv4_sk_update_pmtu);
1144
1145 void ipv4_redirect(struct sk_buff *skb, struct net *net,
1146                    int oif, u8 protocol)
1147 {
1148         const struct iphdr *iph = (const struct iphdr *) skb->data;
1149         struct flowi4 fl4;
1150         struct rtable *rt;
1151
1152         __build_flow_key(net, &fl4, NULL, iph, oif,
1153                          RT_TOS(iph->tos), protocol, 0, 0);
1154         rt = __ip_route_output_key(net, &fl4);
1155         if (!IS_ERR(rt)) {
1156                 __ip_do_redirect(rt, skb, &fl4, false);
1157                 ip_rt_put(rt);
1158         }
1159 }
1160 EXPORT_SYMBOL_GPL(ipv4_redirect);
1161
1162 void ipv4_sk_redirect(struct sk_buff *skb, struct sock *sk)
1163 {
1164         const struct iphdr *iph = (const struct iphdr *) skb->data;
1165         struct flowi4 fl4;
1166         struct rtable *rt;
1167         struct net *net = sock_net(sk);
1168
1169         __build_flow_key(net, &fl4, sk, iph, 0, 0, 0, 0, 0);
1170         rt = __ip_route_output_key(net, &fl4);
1171         if (!IS_ERR(rt)) {
1172                 __ip_do_redirect(rt, skb, &fl4, false);
1173                 ip_rt_put(rt);
1174         }
1175 }
1176 EXPORT_SYMBOL_GPL(ipv4_sk_redirect);
1177
1178 static struct dst_entry *ipv4_dst_check(struct dst_entry *dst, u32 cookie)
1179 {
1180         struct rtable *rt = (struct rtable *) dst;
1181
1182         /* All IPV4 dsts are created with ->obsolete set to the value
1183          * DST_OBSOLETE_FORCE_CHK which forces validation calls down
1184          * into this function always.
1185          *
1186          * When a PMTU/redirect information update invalidates a route,
1187          * this is indicated by setting obsolete to DST_OBSOLETE_KILL or
1188          * DST_OBSOLETE_DEAD.
1189          */
1190         if (dst->obsolete != DST_OBSOLETE_FORCE_CHK || rt_is_expired(rt))
1191                 return NULL;
1192         return dst;
1193 }
1194
1195 static void ipv4_send_dest_unreach(struct sk_buff *skb)
1196 {
1197         struct ip_options opt;
1198         int res;
1199
1200         /* Recompile ip options since IPCB may not be valid anymore.
1201          * Also check we have a reasonable ipv4 header.
1202          */
1203         if (!pskb_network_may_pull(skb, sizeof(struct iphdr)) ||
1204             ip_hdr(skb)->version != 4 || ip_hdr(skb)->ihl < 5)
1205                 return;
1206
1207         memset(&opt, 0, sizeof(opt));
1208         if (ip_hdr(skb)->ihl > 5) {
1209                 if (!pskb_network_may_pull(skb, ip_hdr(skb)->ihl * 4))
1210                         return;
1211                 opt.optlen = ip_hdr(skb)->ihl * 4 - sizeof(struct iphdr);
1212
1213                 rcu_read_lock();
1214                 res = __ip_options_compile(dev_net(skb->dev), &opt, skb, NULL);
1215                 rcu_read_unlock();
1216
1217                 if (res)
1218                         return;
1219         }
1220         __icmp_send(skb, ICMP_DEST_UNREACH, ICMP_HOST_UNREACH, 0, &opt);
1221 }
1222
1223 static void ipv4_link_failure(struct sk_buff *skb)
1224 {
1225         struct rtable *rt;
1226
1227         ipv4_send_dest_unreach(skb);
1228
1229         rt = skb_rtable(skb);
1230         if (rt)
1231                 dst_set_expires(&rt->dst, 0);
1232 }
1233
1234 static int ip_rt_bug(struct net *net, struct sock *sk, struct sk_buff *skb)
1235 {
1236         pr_debug("%s: %pI4 -> %pI4, %s\n",
1237                  __func__, &ip_hdr(skb)->saddr, &ip_hdr(skb)->daddr,
1238                  skb->dev ? skb->dev->name : "?");
1239         kfree_skb(skb);
1240         WARN_ON(1);
1241         return 0;
1242 }
1243
1244 /*
1245    We do not cache source address of outgoing interface,
1246    because it is used only by IP RR, TS and SRR options,
1247    so that it out of fast path.
1248
1249    BTW remember: "addr" is allowed to be not aligned
1250    in IP options!
1251  */
1252
1253 void ip_rt_get_source(u8 *addr, struct sk_buff *skb, struct rtable *rt)
1254 {
1255         __be32 src;
1256
1257         if (rt_is_output_route(rt))
1258                 src = ip_hdr(skb)->saddr;
1259         else {
1260                 struct fib_result res;
1261                 struct iphdr *iph = ip_hdr(skb);
1262                 struct flowi4 fl4 = {
1263                         .daddr = iph->daddr,
1264                         .saddr = iph->saddr,
1265                         .flowi4_tos = RT_TOS(iph->tos),
1266                         .flowi4_oif = rt->dst.dev->ifindex,
1267                         .flowi4_iif = skb->dev->ifindex,
1268                         .flowi4_mark = skb->mark,
1269                 };
1270
1271                 rcu_read_lock();
1272                 if (fib_lookup(dev_net(rt->dst.dev), &fl4, &res, 0) == 0)
1273                         src = fib_result_prefsrc(dev_net(rt->dst.dev), &res);
1274                 else
1275                         src = inet_select_addr(rt->dst.dev,
1276                                                rt_nexthop(rt, iph->daddr),
1277                                                RT_SCOPE_UNIVERSE);
1278                 rcu_read_unlock();
1279         }
1280         memcpy(addr, &src, 4);
1281 }
1282
1283 #ifdef CONFIG_IP_ROUTE_CLASSID
1284 static void set_class_tag(struct rtable *rt, u32 tag)
1285 {
1286         if (!(rt->dst.tclassid & 0xFFFF))
1287                 rt->dst.tclassid |= tag & 0xFFFF;
1288         if (!(rt->dst.tclassid & 0xFFFF0000))
1289                 rt->dst.tclassid |= tag & 0xFFFF0000;
1290 }
1291 #endif
1292
1293 static unsigned int ipv4_default_advmss(const struct dst_entry *dst)
1294 {
1295         unsigned int header_size = sizeof(struct tcphdr) + sizeof(struct iphdr);
1296         unsigned int advmss = max_t(unsigned int, ipv4_mtu(dst) - header_size,
1297                                     ip_rt_min_advmss);
1298
1299         return min(advmss, IPV4_MAX_PMTU - header_size);
1300 }
1301
1302 static unsigned int ipv4_mtu(const struct dst_entry *dst)
1303 {
1304         const struct rtable *rt = (const struct rtable *) dst;
1305         unsigned int mtu = rt->rt_pmtu;
1306
1307         if (!mtu || time_after_eq(jiffies, rt->dst.expires))
1308                 mtu = dst_metric_raw(dst, RTAX_MTU);
1309
1310         if (mtu)
1311                 return mtu;
1312
1313         mtu = READ_ONCE(dst->dev->mtu);
1314
1315         if (unlikely(ip_mtu_locked(dst))) {
1316                 if (rt->rt_gw_family && mtu > 576)
1317                         mtu = 576;
1318         }
1319
1320         mtu = min_t(unsigned int, mtu, IP_MAX_MTU);
1321
1322         return mtu - lwtunnel_headroom(dst->lwtstate, mtu);
1323 }
1324
1325 static void ip_del_fnhe(struct fib_nh_common *nhc, __be32 daddr)
1326 {
1327         struct fnhe_hash_bucket *hash;
1328         struct fib_nh_exception *fnhe, __rcu **fnhe_p;
1329         u32 hval = fnhe_hashfun(daddr);
1330
1331         spin_lock_bh(&fnhe_lock);
1332
1333         hash = rcu_dereference_protected(nhc->nhc_exceptions,
1334                                          lockdep_is_held(&fnhe_lock));
1335         hash += hval;
1336
1337         fnhe_p = &hash->chain;
1338         fnhe = rcu_dereference_protected(*fnhe_p, lockdep_is_held(&fnhe_lock));
1339         while (fnhe) {
1340                 if (fnhe->fnhe_daddr == daddr) {
1341                         rcu_assign_pointer(*fnhe_p, rcu_dereference_protected(
1342                                 fnhe->fnhe_next, lockdep_is_held(&fnhe_lock)));
1343                         /* set fnhe_daddr to 0 to ensure it won't bind with
1344                          * new dsts in rt_bind_exception().
1345                          */
1346                         fnhe->fnhe_daddr = 0;
1347                         fnhe_flush_routes(fnhe);
1348                         kfree_rcu(fnhe, rcu);
1349                         break;
1350                 }
1351                 fnhe_p = &fnhe->fnhe_next;
1352                 fnhe = rcu_dereference_protected(fnhe->fnhe_next,
1353                                                  lockdep_is_held(&fnhe_lock));
1354         }
1355
1356         spin_unlock_bh(&fnhe_lock);
1357 }
1358
1359 static struct fib_nh_exception *find_exception(struct fib_nh_common *nhc,
1360                                                __be32 daddr)
1361 {
1362         struct fnhe_hash_bucket *hash = rcu_dereference(nhc->nhc_exceptions);
1363         struct fib_nh_exception *fnhe;
1364         u32 hval;
1365
1366         if (!hash)
1367                 return NULL;
1368
1369         hval = fnhe_hashfun(daddr);
1370
1371         for (fnhe = rcu_dereference(hash[hval].chain); fnhe;
1372              fnhe = rcu_dereference(fnhe->fnhe_next)) {
1373                 if (fnhe->fnhe_daddr == daddr) {
1374                         if (fnhe->fnhe_expires &&
1375                             time_after(jiffies, fnhe->fnhe_expires)) {
1376                                 ip_del_fnhe(nhc, daddr);
1377                                 break;
1378                         }
1379                         return fnhe;
1380                 }
1381         }
1382         return NULL;
1383 }
1384
1385 /* MTU selection:
1386  * 1. mtu on route is locked - use it
1387  * 2. mtu from nexthop exception
1388  * 3. mtu from egress device
1389  */
1390
1391 u32 ip_mtu_from_fib_result(struct fib_result *res, __be32 daddr)
1392 {
1393         struct fib_nh_common *nhc = res->nhc;
1394         struct net_device *dev = nhc->nhc_dev;
1395         struct fib_info *fi = res->fi;
1396         u32 mtu = 0;
1397
1398         if (dev_net(dev)->ipv4.sysctl_ip_fwd_use_pmtu ||
1399             fi->fib_metrics->metrics[RTAX_LOCK - 1] & (1 << RTAX_MTU))
1400                 mtu = fi->fib_mtu;
1401
1402         if (likely(!mtu)) {
1403                 struct fib_nh_exception *fnhe;
1404
1405                 fnhe = find_exception(nhc, daddr);
1406                 if (fnhe && !time_after_eq(jiffies, fnhe->fnhe_expires))
1407                         mtu = fnhe->fnhe_pmtu;
1408         }
1409
1410         if (likely(!mtu))
1411                 mtu = min(READ_ONCE(dev->mtu), IP_MAX_MTU);
1412
1413         return mtu - lwtunnel_headroom(nhc->nhc_lwtstate, mtu);
1414 }
1415
1416 static bool rt_bind_exception(struct rtable *rt, struct fib_nh_exception *fnhe,
1417                               __be32 daddr, const bool do_cache)
1418 {
1419         bool ret = false;
1420
1421         spin_lock_bh(&fnhe_lock);
1422
1423         if (daddr == fnhe->fnhe_daddr) {
1424                 struct rtable __rcu **porig;
1425                 struct rtable *orig;
1426                 int genid = fnhe_genid(dev_net(rt->dst.dev));
1427
1428                 if (rt_is_input_route(rt))
1429                         porig = &fnhe->fnhe_rth_input;
1430                 else
1431                         porig = &fnhe->fnhe_rth_output;
1432                 orig = rcu_dereference(*porig);
1433
1434                 if (fnhe->fnhe_genid != genid) {
1435                         fnhe->fnhe_genid = genid;
1436                         fnhe->fnhe_gw = 0;
1437                         fnhe->fnhe_pmtu = 0;
1438                         fnhe->fnhe_expires = 0;
1439                         fnhe->fnhe_mtu_locked = false;
1440                         fnhe_flush_routes(fnhe);
1441                         orig = NULL;
1442                 }
1443                 fill_route_from_fnhe(rt, fnhe);
1444                 if (!rt->rt_gw4) {
1445                         rt->rt_gw4 = daddr;
1446                         rt->rt_gw_family = AF_INET;
1447                 }
1448
1449                 if (do_cache) {
1450                         dst_hold(&rt->dst);
1451                         rcu_assign_pointer(*porig, rt);
1452                         if (orig) {
1453                                 dst_dev_put(&orig->dst);
1454                                 dst_release(&orig->dst);
1455                         }
1456                         ret = true;
1457                 }
1458
1459                 fnhe->fnhe_stamp = jiffies;
1460         }
1461         spin_unlock_bh(&fnhe_lock);
1462
1463         return ret;
1464 }
1465
1466 static bool rt_cache_route(struct fib_nh_common *nhc, struct rtable *rt)
1467 {
1468         struct rtable *orig, *prev, **p;
1469         bool ret = true;
1470
1471         if (rt_is_input_route(rt)) {
1472                 p = (struct rtable **)&nhc->nhc_rth_input;
1473         } else {
1474                 p = (struct rtable **)raw_cpu_ptr(nhc->nhc_pcpu_rth_output);
1475         }
1476         orig = *p;
1477
1478         /* hold dst before doing cmpxchg() to avoid race condition
1479          * on this dst
1480          */
1481         dst_hold(&rt->dst);
1482         prev = cmpxchg(p, orig, rt);
1483         if (prev == orig) {
1484                 if (orig) {
1485                         dst_dev_put(&orig->dst);
1486                         dst_release(&orig->dst);
1487                 }
1488         } else {
1489                 dst_release(&rt->dst);
1490                 ret = false;
1491         }
1492
1493         return ret;
1494 }
1495
1496 struct uncached_list {
1497         spinlock_t              lock;
1498         struct list_head        head;
1499 };
1500
1501 static DEFINE_PER_CPU_ALIGNED(struct uncached_list, rt_uncached_list);
1502
1503 void rt_add_uncached_list(struct rtable *rt)
1504 {
1505         struct uncached_list *ul = raw_cpu_ptr(&rt_uncached_list);
1506
1507         rt->rt_uncached_list = ul;
1508
1509         spin_lock_bh(&ul->lock);
1510         list_add_tail(&rt->rt_uncached, &ul->head);
1511         spin_unlock_bh(&ul->lock);
1512 }
1513
1514 void rt_del_uncached_list(struct rtable *rt)
1515 {
1516         if (!list_empty(&rt->rt_uncached)) {
1517                 struct uncached_list *ul = rt->rt_uncached_list;
1518
1519                 spin_lock_bh(&ul->lock);
1520                 list_del(&rt->rt_uncached);
1521                 spin_unlock_bh(&ul->lock);
1522         }
1523 }
1524
1525 static void ipv4_dst_destroy(struct dst_entry *dst)
1526 {
1527         struct rtable *rt = (struct rtable *)dst;
1528
1529         ip_dst_metrics_put(dst);
1530         rt_del_uncached_list(rt);
1531 }
1532
1533 void rt_flush_dev(struct net_device *dev)
1534 {
1535         struct net *net = dev_net(dev);
1536         struct rtable *rt;
1537         int cpu;
1538
1539         for_each_possible_cpu(cpu) {
1540                 struct uncached_list *ul = &per_cpu(rt_uncached_list, cpu);
1541
1542                 spin_lock_bh(&ul->lock);
1543                 list_for_each_entry(rt, &ul->head, rt_uncached) {
1544                         if (rt->dst.dev != dev)
1545                                 continue;
1546                         rt->dst.dev = net->loopback_dev;
1547                         dev_hold(rt->dst.dev);
1548                         dev_put(dev);
1549                 }
1550                 spin_unlock_bh(&ul->lock);
1551         }
1552 }
1553
1554 static bool rt_cache_valid(const struct rtable *rt)
1555 {
1556         return  rt &&
1557                 rt->dst.obsolete == DST_OBSOLETE_FORCE_CHK &&
1558                 !rt_is_expired(rt);
1559 }
1560
1561 static void rt_set_nexthop(struct rtable *rt, __be32 daddr,
1562                            const struct fib_result *res,
1563                            struct fib_nh_exception *fnhe,
1564                            struct fib_info *fi, u16 type, u32 itag,
1565                            const bool do_cache)
1566 {
1567         bool cached = false;
1568
1569         if (fi) {
1570                 struct fib_nh_common *nhc = FIB_RES_NHC(*res);
1571
1572                 if (nhc->nhc_gw_family && nhc->nhc_scope == RT_SCOPE_LINK) {
1573                         rt->rt_gw_family = nhc->nhc_gw_family;
1574                         /* only INET and INET6 are supported */
1575                         if (likely(nhc->nhc_gw_family == AF_INET))
1576                                 rt->rt_gw4 = nhc->nhc_gw.ipv4;
1577                         else
1578                                 rt->rt_gw6 = nhc->nhc_gw.ipv6;
1579                 }
1580
1581                 ip_dst_init_metrics(&rt->dst, fi->fib_metrics);
1582
1583 #ifdef CONFIG_IP_ROUTE_CLASSID
1584                 if (nhc->nhc_family == AF_INET) {
1585                         struct fib_nh *nh;
1586
1587                         nh = container_of(nhc, struct fib_nh, nh_common);
1588                         rt->dst.tclassid = nh->nh_tclassid;
1589                 }
1590 #endif
1591                 rt->dst.lwtstate = lwtstate_get(nhc->nhc_lwtstate);
1592                 if (unlikely(fnhe))
1593                         cached = rt_bind_exception(rt, fnhe, daddr, do_cache);
1594                 else if (do_cache)
1595                         cached = rt_cache_route(nhc, rt);
1596                 if (unlikely(!cached)) {
1597                         /* Routes we intend to cache in nexthop exception or
1598                          * FIB nexthop have the DST_NOCACHE bit clear.
1599                          * However, if we are unsuccessful at storing this
1600                          * route into the cache we really need to set it.
1601                          */
1602                         if (!rt->rt_gw4) {
1603                                 rt->rt_gw_family = AF_INET;
1604                                 rt->rt_gw4 = daddr;
1605                         }
1606                         rt_add_uncached_list(rt);
1607                 }
1608         } else
1609                 rt_add_uncached_list(rt);
1610
1611 #ifdef CONFIG_IP_ROUTE_CLASSID
1612 #ifdef CONFIG_IP_MULTIPLE_TABLES
1613         set_class_tag(rt, res->tclassid);
1614 #endif
1615         set_class_tag(rt, itag);
1616 #endif
1617 }
1618
1619 struct rtable *rt_dst_alloc(struct net_device *dev,
1620                             unsigned int flags, u16 type,
1621                             bool nopolicy, bool noxfrm, bool will_cache)
1622 {
1623         struct rtable *rt;
1624
1625         rt = dst_alloc(&ipv4_dst_ops, dev, 1, DST_OBSOLETE_FORCE_CHK,
1626                        (will_cache ? 0 : DST_HOST) |
1627                        (nopolicy ? DST_NOPOLICY : 0) |
1628                        (noxfrm ? DST_NOXFRM : 0));
1629
1630         if (rt) {
1631                 rt->rt_genid = rt_genid_ipv4(dev_net(dev));
1632                 rt->rt_flags = flags;
1633                 rt->rt_type = type;
1634                 rt->rt_is_input = 0;
1635                 rt->rt_iif = 0;
1636                 rt->rt_pmtu = 0;
1637                 rt->rt_mtu_locked = 0;
1638                 rt->rt_gw_family = 0;
1639                 rt->rt_gw4 = 0;
1640                 INIT_LIST_HEAD(&rt->rt_uncached);
1641
1642                 rt->dst.output = ip_output;
1643                 if (flags & RTCF_LOCAL)
1644                         rt->dst.input = ip_local_deliver;
1645         }
1646
1647         return rt;
1648 }
1649 EXPORT_SYMBOL(rt_dst_alloc);
1650
1651 struct rtable *rt_dst_clone(struct net_device *dev, struct rtable *rt)
1652 {
1653         struct rtable *new_rt;
1654
1655         new_rt = dst_alloc(&ipv4_dst_ops, dev, 1, DST_OBSOLETE_FORCE_CHK,
1656                            rt->dst.flags);
1657
1658         if (new_rt) {
1659                 new_rt->rt_genid = rt_genid_ipv4(dev_net(dev));
1660                 new_rt->rt_flags = rt->rt_flags;
1661                 new_rt->rt_type = rt->rt_type;
1662                 new_rt->rt_is_input = rt->rt_is_input;
1663                 new_rt->rt_iif = rt->rt_iif;
1664                 new_rt->rt_pmtu = rt->rt_pmtu;
1665                 new_rt->rt_mtu_locked = rt->rt_mtu_locked;
1666                 new_rt->rt_gw_family = rt->rt_gw_family;
1667                 if (rt->rt_gw_family == AF_INET)
1668                         new_rt->rt_gw4 = rt->rt_gw4;
1669                 else if (rt->rt_gw_family == AF_INET6)
1670                         new_rt->rt_gw6 = rt->rt_gw6;
1671                 INIT_LIST_HEAD(&new_rt->rt_uncached);
1672
1673                 new_rt->dst.flags |= DST_HOST;
1674                 new_rt->dst.input = rt->dst.input;
1675                 new_rt->dst.output = rt->dst.output;
1676                 new_rt->dst.error = rt->dst.error;
1677                 new_rt->dst.lastuse = jiffies;
1678                 new_rt->dst.lwtstate = lwtstate_get(rt->dst.lwtstate);
1679         }
1680         return new_rt;
1681 }
1682 EXPORT_SYMBOL(rt_dst_clone);
1683
1684 /* called in rcu_read_lock() section */
1685 int ip_mc_validate_source(struct sk_buff *skb, __be32 daddr, __be32 saddr,
1686                           u8 tos, struct net_device *dev,
1687                           struct in_device *in_dev, u32 *itag)
1688 {
1689         int err;
1690
1691         /* Primary sanity checks. */
1692         if (!in_dev)
1693                 return -EINVAL;
1694
1695         if (ipv4_is_multicast(saddr) || ipv4_is_lbcast(saddr) ||
1696             skb->protocol != htons(ETH_P_IP))
1697                 return -EINVAL;
1698
1699         if (ipv4_is_loopback(saddr) && !IN_DEV_ROUTE_LOCALNET(in_dev))
1700                 return -EINVAL;
1701
1702         if (ipv4_is_zeronet(saddr)) {
1703                 if (!ipv4_is_local_multicast(daddr) &&
1704                     ip_hdr(skb)->protocol != IPPROTO_IGMP)
1705                         return -EINVAL;
1706         } else {
1707                 err = fib_validate_source(skb, saddr, 0, tos, 0, dev,
1708                                           in_dev, itag);
1709                 if (err < 0)
1710                         return err;
1711         }
1712         return 0;
1713 }
1714
1715 /* called in rcu_read_lock() section */
1716 static int ip_route_input_mc(struct sk_buff *skb, __be32 daddr, __be32 saddr,
1717                              u8 tos, struct net_device *dev, int our)
1718 {
1719         struct in_device *in_dev = __in_dev_get_rcu(dev);
1720         unsigned int flags = RTCF_MULTICAST;
1721         struct rtable *rth;
1722         u32 itag = 0;
1723         int err;
1724
1725         err = ip_mc_validate_source(skb, daddr, saddr, tos, dev, in_dev, &itag);
1726         if (err)
1727                 return err;
1728
1729         if (our)
1730                 flags |= RTCF_LOCAL;
1731
1732         rth = rt_dst_alloc(dev_net(dev)->loopback_dev, flags, RTN_MULTICAST,
1733                            IN_DEV_CONF_GET(in_dev, NOPOLICY), false, false);
1734         if (!rth)
1735                 return -ENOBUFS;
1736
1737 #ifdef CONFIG_IP_ROUTE_CLASSID
1738         rth->dst.tclassid = itag;
1739 #endif
1740         rth->dst.output = ip_rt_bug;
1741         rth->rt_is_input= 1;
1742
1743 #ifdef CONFIG_IP_MROUTE
1744         if (!ipv4_is_local_multicast(daddr) && IN_DEV_MFORWARD(in_dev))
1745                 rth->dst.input = ip_mr_input;
1746 #endif
1747         RT_CACHE_STAT_INC(in_slow_mc);
1748
1749         skb_dst_set(skb, &rth->dst);
1750         return 0;
1751 }
1752
1753
1754 static void ip_handle_martian_source(struct net_device *dev,
1755                                      struct in_device *in_dev,
1756                                      struct sk_buff *skb,
1757                                      __be32 daddr,
1758                                      __be32 saddr)
1759 {
1760         RT_CACHE_STAT_INC(in_martian_src);
1761 #ifdef CONFIG_IP_ROUTE_VERBOSE
1762         if (IN_DEV_LOG_MARTIANS(in_dev) && net_ratelimit()) {
1763                 /*
1764                  *      RFC1812 recommendation, if source is martian,
1765                  *      the only hint is MAC header.
1766                  */
1767                 pr_warn("martian source %pI4 from %pI4, on dev %s\n",
1768                         &daddr, &saddr, dev->name);
1769                 if (dev->hard_header_len && skb_mac_header_was_set(skb)) {
1770                         print_hex_dump(KERN_WARNING, "ll header: ",
1771                                        DUMP_PREFIX_OFFSET, 16, 1,
1772                                        skb_mac_header(skb),
1773                                        dev->hard_header_len, false);
1774                 }
1775         }
1776 #endif
1777 }
1778
1779 /* called in rcu_read_lock() section */
1780 static int __mkroute_input(struct sk_buff *skb,
1781                            const struct fib_result *res,
1782                            struct in_device *in_dev,
1783                            __be32 daddr, __be32 saddr, u32 tos)
1784 {
1785         struct fib_nh_common *nhc = FIB_RES_NHC(*res);
1786         struct net_device *dev = nhc->nhc_dev;
1787         struct fib_nh_exception *fnhe;
1788         struct rtable *rth;
1789         int err;
1790         struct in_device *out_dev;
1791         bool do_cache;
1792         u32 itag = 0;
1793
1794         /* get a working reference to the output device */
1795         out_dev = __in_dev_get_rcu(dev);
1796         if (!out_dev) {
1797                 net_crit_ratelimited("Bug in ip_route_input_slow(). Please report.\n");
1798                 return -EINVAL;
1799         }
1800
1801         err = fib_validate_source(skb, saddr, daddr, tos, FIB_RES_OIF(*res),
1802                                   in_dev->dev, in_dev, &itag);
1803         if (err < 0) {
1804                 ip_handle_martian_source(in_dev->dev, in_dev, skb, daddr,
1805                                          saddr);
1806
1807                 goto cleanup;
1808         }
1809
1810         do_cache = res->fi && !itag;
1811         if (out_dev == in_dev && err && IN_DEV_TX_REDIRECTS(out_dev) &&
1812             skb->protocol == htons(ETH_P_IP)) {
1813                 __be32 gw;
1814
1815                 gw = nhc->nhc_gw_family == AF_INET ? nhc->nhc_gw.ipv4 : 0;
1816                 if (IN_DEV_SHARED_MEDIA(out_dev) ||
1817                     inet_addr_onlink(out_dev, saddr, gw))
1818                         IPCB(skb)->flags |= IPSKB_DOREDIRECT;
1819         }
1820
1821         if (skb->protocol != htons(ETH_P_IP)) {
1822                 /* Not IP (i.e. ARP). Do not create route, if it is
1823                  * invalid for proxy arp. DNAT routes are always valid.
1824                  *
1825                  * Proxy arp feature have been extended to allow, ARP
1826                  * replies back to the same interface, to support
1827                  * Private VLAN switch technologies. See arp.c.
1828                  */
1829                 if (out_dev == in_dev &&
1830                     IN_DEV_PROXY_ARP_PVLAN(in_dev) == 0) {
1831                         err = -EINVAL;
1832                         goto cleanup;
1833                 }
1834         }
1835
1836         fnhe = find_exception(nhc, daddr);
1837         if (do_cache) {
1838                 if (fnhe)
1839                         rth = rcu_dereference(fnhe->fnhe_rth_input);
1840                 else
1841                         rth = rcu_dereference(nhc->nhc_rth_input);
1842                 if (rt_cache_valid(rth)) {
1843                         skb_dst_set_noref(skb, &rth->dst);
1844                         goto out;
1845                 }
1846         }
1847
1848         rth = rt_dst_alloc(out_dev->dev, 0, res->type,
1849                            IN_DEV_CONF_GET(in_dev, NOPOLICY),
1850                            IN_DEV_CONF_GET(out_dev, NOXFRM), do_cache);
1851         if (!rth) {
1852                 err = -ENOBUFS;
1853                 goto cleanup;
1854         }
1855
1856         rth->rt_is_input = 1;
1857         RT_CACHE_STAT_INC(in_slow_tot);
1858
1859         rth->dst.input = ip_forward;
1860
1861         rt_set_nexthop(rth, daddr, res, fnhe, res->fi, res->type, itag,
1862                        do_cache);
1863         lwtunnel_set_redirect(&rth->dst);
1864         skb_dst_set(skb, &rth->dst);
1865 out:
1866         err = 0;
1867  cleanup:
1868         return err;
1869 }
1870
1871 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1872 /* To make ICMP packets follow the right flow, the multipath hash is
1873  * calculated from the inner IP addresses.
1874  */
1875 static void ip_multipath_l3_keys(const struct sk_buff *skb,
1876                                  struct flow_keys *hash_keys)
1877 {
1878         const struct iphdr *outer_iph = ip_hdr(skb);
1879         const struct iphdr *key_iph = outer_iph;
1880         const struct iphdr *inner_iph;
1881         const struct icmphdr *icmph;
1882         struct iphdr _inner_iph;
1883         struct icmphdr _icmph;
1884
1885         if (likely(outer_iph->protocol != IPPROTO_ICMP))
1886                 goto out;
1887
1888         if (unlikely((outer_iph->frag_off & htons(IP_OFFSET)) != 0))
1889                 goto out;
1890
1891         icmph = skb_header_pointer(skb, outer_iph->ihl * 4, sizeof(_icmph),
1892                                    &_icmph);
1893         if (!icmph)
1894                 goto out;
1895
1896         if (icmph->type != ICMP_DEST_UNREACH &&
1897             icmph->type != ICMP_REDIRECT &&
1898             icmph->type != ICMP_TIME_EXCEEDED &&
1899             icmph->type != ICMP_PARAMETERPROB)
1900                 goto out;
1901
1902         inner_iph = skb_header_pointer(skb,
1903                                        outer_iph->ihl * 4 + sizeof(_icmph),
1904                                        sizeof(_inner_iph), &_inner_iph);
1905         if (!inner_iph)
1906                 goto out;
1907
1908         key_iph = inner_iph;
1909 out:
1910         hash_keys->addrs.v4addrs.src = key_iph->saddr;
1911         hash_keys->addrs.v4addrs.dst = key_iph->daddr;
1912 }
1913
1914 /* if skb is set it will be used and fl4 can be NULL */
1915 int fib_multipath_hash(const struct net *net, const struct flowi4 *fl4,
1916                        const struct sk_buff *skb, struct flow_keys *flkeys)
1917 {
1918         u32 multipath_hash = fl4 ? fl4->flowi4_multipath_hash : 0;
1919         struct flow_keys hash_keys;
1920         u32 mhash;
1921
1922         switch (net->ipv4.sysctl_fib_multipath_hash_policy) {
1923         case 0:
1924                 memset(&hash_keys, 0, sizeof(hash_keys));
1925                 hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS;
1926                 if (skb) {
1927                         ip_multipath_l3_keys(skb, &hash_keys);
1928                 } else {
1929                         hash_keys.addrs.v4addrs.src = fl4->saddr;
1930                         hash_keys.addrs.v4addrs.dst = fl4->daddr;
1931                 }
1932                 break;
1933         case 1:
1934                 /* skb is currently provided only when forwarding */
1935                 if (skb) {
1936                         unsigned int flag = FLOW_DISSECTOR_F_STOP_AT_ENCAP;
1937                         struct flow_keys keys;
1938
1939                         /* short-circuit if we already have L4 hash present */
1940                         if (skb->l4_hash)
1941                                 return skb_get_hash_raw(skb) >> 1;
1942
1943                         memset(&hash_keys, 0, sizeof(hash_keys));
1944
1945                         if (!flkeys) {
1946                                 skb_flow_dissect_flow_keys(skb, &keys, flag);
1947                                 flkeys = &keys;
1948                         }
1949
1950                         hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS;
1951                         hash_keys.addrs.v4addrs.src = flkeys->addrs.v4addrs.src;
1952                         hash_keys.addrs.v4addrs.dst = flkeys->addrs.v4addrs.dst;
1953                         hash_keys.ports.src = flkeys->ports.src;
1954                         hash_keys.ports.dst = flkeys->ports.dst;
1955                         hash_keys.basic.ip_proto = flkeys->basic.ip_proto;
1956                 } else {
1957                         memset(&hash_keys, 0, sizeof(hash_keys));
1958                         hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS;
1959                         hash_keys.addrs.v4addrs.src = fl4->saddr;
1960                         hash_keys.addrs.v4addrs.dst = fl4->daddr;
1961                         hash_keys.ports.src = fl4->fl4_sport;
1962                         hash_keys.ports.dst = fl4->fl4_dport;
1963                         hash_keys.basic.ip_proto = fl4->flowi4_proto;
1964                 }
1965                 break;
1966         case 2:
1967                 memset(&hash_keys, 0, sizeof(hash_keys));
1968                 hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS;
1969                 /* skb is currently provided only when forwarding */
1970                 if (skb) {
1971                         struct flow_keys keys;
1972
1973                         skb_flow_dissect_flow_keys(skb, &keys, 0);
1974
1975                         hash_keys.addrs.v4addrs.src = keys.addrs.v4addrs.src;
1976                         hash_keys.addrs.v4addrs.dst = keys.addrs.v4addrs.dst;
1977                 } else {
1978                         /* Same as case 0 */
1979                         hash_keys.addrs.v4addrs.src = fl4->saddr;
1980                         hash_keys.addrs.v4addrs.dst = fl4->daddr;
1981                 }
1982                 break;
1983         }
1984         mhash = flow_hash_from_keys(&hash_keys);
1985
1986         if (multipath_hash)
1987                 mhash = jhash_2words(mhash, multipath_hash, 0);
1988
1989         return mhash >> 1;
1990 }
1991 #endif /* CONFIG_IP_ROUTE_MULTIPATH */
1992
1993 static int ip_mkroute_input(struct sk_buff *skb,
1994                             struct fib_result *res,
1995                             struct in_device *in_dev,
1996                             __be32 daddr, __be32 saddr, u32 tos,
1997                             struct flow_keys *hkeys)
1998 {
1999 #ifdef CONFIG_IP_ROUTE_MULTIPATH
2000         if (res->fi && fib_info_num_path(res->fi) > 1) {
2001                 int h = fib_multipath_hash(res->fi->fib_net, NULL, skb, hkeys);
2002
2003                 fib_select_multipath(res, h);
2004         }
2005 #endif
2006
2007         /* create a routing cache entry */
2008         return __mkroute_input(skb, res, in_dev, daddr, saddr, tos);
2009 }
2010
2011 /*
2012  *      NOTE. We drop all the packets that has local source
2013  *      addresses, because every properly looped back packet
2014  *      must have correct destination already attached by output routine.
2015  *
2016  *      Such approach solves two big problems:
2017  *      1. Not simplex devices are handled properly.
2018  *      2. IP spoofing attempts are filtered with 100% of guarantee.
2019  *      called with rcu_read_lock()
2020  */
2021
2022 static int ip_route_input_slow(struct sk_buff *skb, __be32 daddr, __be32 saddr,
2023                                u8 tos, struct net_device *dev,
2024                                struct fib_result *res)
2025 {
2026         struct in_device *in_dev = __in_dev_get_rcu(dev);
2027         struct flow_keys *flkeys = NULL, _flkeys;
2028         struct net    *net = dev_net(dev);
2029         struct ip_tunnel_info *tun_info;
2030         int             err = -EINVAL;
2031         unsigned int    flags = 0;
2032         u32             itag = 0;
2033         struct rtable   *rth;
2034         struct flowi4   fl4;
2035         bool do_cache = true;
2036
2037         /* IP on this device is disabled. */
2038
2039         if (!in_dev)
2040                 goto out;
2041
2042         /* Check for the most weird martians, which can be not detected
2043            by fib_lookup.
2044          */
2045
2046         tun_info = skb_tunnel_info(skb);
2047         if (tun_info && !(tun_info->mode & IP_TUNNEL_INFO_TX))
2048                 fl4.flowi4_tun_key.tun_id = tun_info->key.tun_id;
2049         else
2050                 fl4.flowi4_tun_key.tun_id = 0;
2051         skb_dst_drop(skb);
2052
2053         if (ipv4_is_multicast(saddr) || ipv4_is_lbcast(saddr))
2054                 goto martian_source;
2055
2056         res->fi = NULL;
2057         res->table = NULL;
2058         if (ipv4_is_lbcast(daddr) || (saddr == 0 && daddr == 0))
2059                 goto brd_input;
2060
2061         /* Accept zero addresses only to limited broadcast;
2062          * I even do not know to fix it or not. Waiting for complains :-)
2063          */
2064         if (ipv4_is_zeronet(saddr))
2065                 goto martian_source;
2066
2067         if (ipv4_is_zeronet(daddr))
2068                 goto martian_destination;
2069
2070         /* Following code try to avoid calling IN_DEV_NET_ROUTE_LOCALNET(),
2071          * and call it once if daddr or/and saddr are loopback addresses
2072          */
2073         if (ipv4_is_loopback(daddr)) {
2074                 if (!IN_DEV_NET_ROUTE_LOCALNET(in_dev, net))
2075                         goto martian_destination;
2076         } else if (ipv4_is_loopback(saddr)) {
2077                 if (!IN_DEV_NET_ROUTE_LOCALNET(in_dev, net))
2078                         goto martian_source;
2079         }
2080
2081         /*
2082          *      Now we are ready to route packet.
2083          */
2084         fl4.flowi4_oif = 0;
2085         fl4.flowi4_iif = dev->ifindex;
2086         fl4.flowi4_mark = skb->mark;
2087         fl4.flowi4_tos = tos;
2088         fl4.flowi4_scope = RT_SCOPE_UNIVERSE;
2089         fl4.flowi4_flags = 0;
2090         fl4.daddr = daddr;
2091         fl4.saddr = saddr;
2092         fl4.flowi4_uid = sock_net_uid(net, NULL);
2093
2094         if (fib4_rules_early_flow_dissect(net, skb, &fl4, &_flkeys)) {
2095                 flkeys = &_flkeys;
2096         } else {
2097                 fl4.flowi4_proto = 0;
2098                 fl4.fl4_sport = 0;
2099                 fl4.fl4_dport = 0;
2100         }
2101
2102         err = fib_lookup(net, &fl4, res, 0);
2103         if (err != 0) {
2104                 if (!IN_DEV_FORWARD(in_dev))
2105                         err = -EHOSTUNREACH;
2106                 goto no_route;
2107         }
2108
2109         if (res->type == RTN_BROADCAST) {
2110                 if (IN_DEV_BFORWARD(in_dev))
2111                         goto make_route;
2112                 /* not do cache if bc_forwarding is enabled */
2113                 if (IPV4_DEVCONF_ALL(net, BC_FORWARDING))
2114                         do_cache = false;
2115                 goto brd_input;
2116         }
2117
2118         if (res->type == RTN_LOCAL) {
2119                 err = fib_validate_source(skb, saddr, daddr, tos,
2120                                           0, dev, in_dev, &itag);
2121                 if (err < 0)
2122                         goto martian_source;
2123                 goto local_input;
2124         }
2125
2126         if (!IN_DEV_FORWARD(in_dev)) {
2127                 err = -EHOSTUNREACH;
2128                 goto no_route;
2129         }
2130         if (res->type != RTN_UNICAST)
2131                 goto martian_destination;
2132
2133 make_route:
2134         err = ip_mkroute_input(skb, res, in_dev, daddr, saddr, tos, flkeys);
2135 out:    return err;
2136
2137 brd_input:
2138         if (skb->protocol != htons(ETH_P_IP))
2139                 goto e_inval;
2140
2141         if (!ipv4_is_zeronet(saddr)) {
2142                 err = fib_validate_source(skb, saddr, 0, tos, 0, dev,
2143                                           in_dev, &itag);
2144                 if (err < 0)
2145                         goto martian_source;
2146         }
2147         flags |= RTCF_BROADCAST;
2148         res->type = RTN_BROADCAST;
2149         RT_CACHE_STAT_INC(in_brd);
2150
2151 local_input:
2152         do_cache &= res->fi && !itag;
2153         if (do_cache) {
2154                 struct fib_nh_common *nhc = FIB_RES_NHC(*res);
2155
2156                 rth = rcu_dereference(nhc->nhc_rth_input);
2157                 if (rt_cache_valid(rth)) {
2158                         skb_dst_set_noref(skb, &rth->dst);
2159                         err = 0;
2160                         goto out;
2161                 }
2162         }
2163
2164         rth = rt_dst_alloc(l3mdev_master_dev_rcu(dev) ? : net->loopback_dev,
2165                            flags | RTCF_LOCAL, res->type,
2166                            IN_DEV_CONF_GET(in_dev, NOPOLICY), false, do_cache);
2167         if (!rth)
2168                 goto e_nobufs;
2169
2170         rth->dst.output= ip_rt_bug;
2171 #ifdef CONFIG_IP_ROUTE_CLASSID
2172         rth->dst.tclassid = itag;
2173 #endif
2174         rth->rt_is_input = 1;
2175
2176         RT_CACHE_STAT_INC(in_slow_tot);
2177         if (res->type == RTN_UNREACHABLE) {
2178                 rth->dst.input= ip_error;
2179                 rth->dst.error= -err;
2180                 rth->rt_flags   &= ~RTCF_LOCAL;
2181         }
2182
2183         if (do_cache) {
2184                 struct fib_nh_common *nhc = FIB_RES_NHC(*res);
2185
2186                 rth->dst.lwtstate = lwtstate_get(nhc->nhc_lwtstate);
2187                 if (lwtunnel_input_redirect(rth->dst.lwtstate)) {
2188                         WARN_ON(rth->dst.input == lwtunnel_input);
2189                         rth->dst.lwtstate->orig_input = rth->dst.input;
2190                         rth->dst.input = lwtunnel_input;
2191                 }
2192
2193                 if (unlikely(!rt_cache_route(nhc, rth)))
2194                         rt_add_uncached_list(rth);
2195         }
2196         skb_dst_set(skb, &rth->dst);
2197         err = 0;
2198         goto out;
2199
2200 no_route:
2201         RT_CACHE_STAT_INC(in_no_route);
2202         res->type = RTN_UNREACHABLE;
2203         res->fi = NULL;
2204         res->table = NULL;
2205         goto local_input;
2206
2207         /*
2208          *      Do not cache martian addresses: they should be logged (RFC1812)
2209          */
2210 martian_destination:
2211         RT_CACHE_STAT_INC(in_martian_dst);
2212 #ifdef CONFIG_IP_ROUTE_VERBOSE
2213         if (IN_DEV_LOG_MARTIANS(in_dev))
2214                 net_warn_ratelimited("martian destination %pI4 from %pI4, dev %s\n",
2215                                      &daddr, &saddr, dev->name);
2216 #endif
2217
2218 e_inval:
2219         err = -EINVAL;
2220         goto out;
2221
2222 e_nobufs:
2223         err = -ENOBUFS;
2224         goto out;
2225
2226 martian_source:
2227         ip_handle_martian_source(dev, in_dev, skb, daddr, saddr);
2228         goto out;
2229 }
2230
2231 int ip_route_input_noref(struct sk_buff *skb, __be32 daddr, __be32 saddr,
2232                          u8 tos, struct net_device *dev)
2233 {
2234         struct fib_result res;
2235         int err;
2236
2237         tos &= IPTOS_RT_MASK;
2238         rcu_read_lock();
2239         err = ip_route_input_rcu(skb, daddr, saddr, tos, dev, &res);
2240         rcu_read_unlock();
2241
2242         return err;
2243 }
2244 EXPORT_SYMBOL(ip_route_input_noref);
2245
2246 /* called with rcu_read_lock held */
2247 int ip_route_input_rcu(struct sk_buff *skb, __be32 daddr, __be32 saddr,
2248                        u8 tos, struct net_device *dev, struct fib_result *res)
2249 {
2250         /* Multicast recognition logic is moved from route cache to here.
2251            The problem was that too many Ethernet cards have broken/missing
2252            hardware multicast filters :-( As result the host on multicasting
2253            network acquires a lot of useless route cache entries, sort of
2254            SDR messages from all the world. Now we try to get rid of them.
2255            Really, provided software IP multicast filter is organized
2256            reasonably (at least, hashed), it does not result in a slowdown
2257            comparing with route cache reject entries.
2258            Note, that multicast routers are not affected, because
2259            route cache entry is created eventually.
2260          */
2261         if (ipv4_is_multicast(daddr)) {
2262                 struct in_device *in_dev = __in_dev_get_rcu(dev);
2263                 int our = 0;
2264                 int err = -EINVAL;
2265
2266                 if (!in_dev)
2267                         return err;
2268                 our = ip_check_mc_rcu(in_dev, daddr, saddr,
2269                                       ip_hdr(skb)->protocol);
2270
2271                 /* check l3 master if no match yet */
2272                 if (!our && netif_is_l3_slave(dev)) {
2273                         struct in_device *l3_in_dev;
2274
2275                         l3_in_dev = __in_dev_get_rcu(skb->dev);
2276                         if (l3_in_dev)
2277                                 our = ip_check_mc_rcu(l3_in_dev, daddr, saddr,
2278                                                       ip_hdr(skb)->protocol);
2279                 }
2280
2281                 if (our
2282 #ifdef CONFIG_IP_MROUTE
2283                         ||
2284                     (!ipv4_is_local_multicast(daddr) &&
2285                      IN_DEV_MFORWARD(in_dev))
2286 #endif
2287                    ) {
2288                         err = ip_route_input_mc(skb, daddr, saddr,
2289                                                 tos, dev, our);
2290                 }
2291                 return err;
2292         }
2293
2294         return ip_route_input_slow(skb, daddr, saddr, tos, dev, res);
2295 }
2296
2297 /* called with rcu_read_lock() */
2298 static struct rtable *__mkroute_output(const struct fib_result *res,
2299                                        const struct flowi4 *fl4, int orig_oif,
2300                                        struct net_device *dev_out,
2301                                        unsigned int flags)
2302 {
2303         struct fib_info *fi = res->fi;
2304         struct fib_nh_exception *fnhe;
2305         struct in_device *in_dev;
2306         u16 type = res->type;
2307         struct rtable *rth;
2308         bool do_cache;
2309
2310         in_dev = __in_dev_get_rcu(dev_out);
2311         if (!in_dev)
2312                 return ERR_PTR(-EINVAL);
2313
2314         if (likely(!IN_DEV_ROUTE_LOCALNET(in_dev)))
2315                 if (ipv4_is_loopback(fl4->saddr) &&
2316                     !(dev_out->flags & IFF_LOOPBACK) &&
2317                     !netif_is_l3_master(dev_out))
2318                         return ERR_PTR(-EINVAL);
2319
2320         if (ipv4_is_lbcast(fl4->daddr))
2321                 type = RTN_BROADCAST;
2322         else if (ipv4_is_multicast(fl4->daddr))
2323                 type = RTN_MULTICAST;
2324         else if (ipv4_is_zeronet(fl4->daddr))
2325                 return ERR_PTR(-EINVAL);
2326
2327         if (dev_out->flags & IFF_LOOPBACK)
2328                 flags |= RTCF_LOCAL;
2329
2330         do_cache = true;
2331         if (type == RTN_BROADCAST) {
2332                 flags |= RTCF_BROADCAST | RTCF_LOCAL;
2333                 fi = NULL;
2334         } else if (type == RTN_MULTICAST) {
2335                 flags |= RTCF_MULTICAST | RTCF_LOCAL;
2336                 if (!ip_check_mc_rcu(in_dev, fl4->daddr, fl4->saddr,
2337                                      fl4->flowi4_proto))
2338                         flags &= ~RTCF_LOCAL;
2339                 else
2340                         do_cache = false;
2341                 /* If multicast route do not exist use
2342                  * default one, but do not gateway in this case.
2343                  * Yes, it is hack.
2344                  */
2345                 if (fi && res->prefixlen < 4)
2346                         fi = NULL;
2347         } else if ((type == RTN_LOCAL) && (orig_oif != 0) &&
2348                    (orig_oif != dev_out->ifindex)) {
2349                 /* For local routes that require a particular output interface
2350                  * we do not want to cache the result.  Caching the result
2351                  * causes incorrect behaviour when there are multiple source
2352                  * addresses on the interface, the end result being that if the
2353                  * intended recipient is waiting on that interface for the
2354                  * packet he won't receive it because it will be delivered on
2355                  * the loopback interface and the IP_PKTINFO ipi_ifindex will
2356                  * be set to the loopback interface as well.
2357                  */
2358                 do_cache = false;
2359         }
2360
2361         fnhe = NULL;
2362         do_cache &= fi != NULL;
2363         if (fi) {
2364                 struct fib_nh_common *nhc = FIB_RES_NHC(*res);
2365                 struct rtable __rcu **prth;
2366
2367                 fnhe = find_exception(nhc, fl4->daddr);
2368                 if (!do_cache)
2369                         goto add;
2370                 if (fnhe) {
2371                         prth = &fnhe->fnhe_rth_output;
2372                 } else {
2373                         if (unlikely(fl4->flowi4_flags &
2374                                      FLOWI_FLAG_KNOWN_NH &&
2375                                      !(nhc->nhc_gw_family &&
2376                                        nhc->nhc_scope == RT_SCOPE_LINK))) {
2377                                 do_cache = false;
2378                                 goto add;
2379                         }
2380                         prth = raw_cpu_ptr(nhc->nhc_pcpu_rth_output);
2381                 }
2382                 rth = rcu_dereference(*prth);
2383                 if (rt_cache_valid(rth) && dst_hold_safe(&rth->dst))
2384                         return rth;
2385         }
2386
2387 add:
2388         rth = rt_dst_alloc(dev_out, flags, type,
2389                            IN_DEV_CONF_GET(in_dev, NOPOLICY),
2390                            IN_DEV_CONF_GET(in_dev, NOXFRM),
2391                            do_cache);
2392         if (!rth)
2393                 return ERR_PTR(-ENOBUFS);
2394
2395         rth->rt_iif = orig_oif;
2396
2397         RT_CACHE_STAT_INC(out_slow_tot);
2398
2399         if (flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
2400                 if (flags & RTCF_LOCAL &&
2401                     !(dev_out->flags & IFF_LOOPBACK)) {
2402                         rth->dst.output = ip_mc_output;
2403                         RT_CACHE_STAT_INC(out_slow_mc);
2404                 }
2405 #ifdef CONFIG_IP_MROUTE
2406                 if (type == RTN_MULTICAST) {
2407                         if (IN_DEV_MFORWARD(in_dev) &&
2408                             !ipv4_is_local_multicast(fl4->daddr)) {
2409                                 rth->dst.input = ip_mr_input;
2410                                 rth->dst.output = ip_mc_output;
2411                         }
2412                 }
2413 #endif
2414         }
2415
2416         rt_set_nexthop(rth, fl4->daddr, res, fnhe, fi, type, 0, do_cache);
2417         lwtunnel_set_redirect(&rth->dst);
2418
2419         return rth;
2420 }
2421
2422 /*
2423  * Major route resolver routine.
2424  */
2425
2426 struct rtable *ip_route_output_key_hash(struct net *net, struct flowi4 *fl4,
2427                                         const struct sk_buff *skb)
2428 {
2429         __u8 tos = RT_FL_TOS(fl4);
2430         struct fib_result res = {
2431                 .type           = RTN_UNSPEC,
2432                 .fi             = NULL,
2433                 .table          = NULL,
2434                 .tclassid       = 0,
2435         };
2436         struct rtable *rth;
2437
2438         fl4->flowi4_iif = LOOPBACK_IFINDEX;
2439         fl4->flowi4_tos = tos & IPTOS_RT_MASK;
2440         fl4->flowi4_scope = ((tos & RTO_ONLINK) ?
2441                          RT_SCOPE_LINK : RT_SCOPE_UNIVERSE);
2442
2443         rcu_read_lock();
2444         rth = ip_route_output_key_hash_rcu(net, fl4, &res, skb);
2445         rcu_read_unlock();
2446
2447         return rth;
2448 }
2449 EXPORT_SYMBOL_GPL(ip_route_output_key_hash);
2450
2451 struct rtable *ip_route_output_key_hash_rcu(struct net *net, struct flowi4 *fl4,
2452                                             struct fib_result *res,
2453                                             const struct sk_buff *skb)
2454 {
2455         struct net_device *dev_out = NULL;
2456         int orig_oif = fl4->flowi4_oif;
2457         unsigned int flags = 0;
2458         struct rtable *rth;
2459         int err = -ENETUNREACH;
2460
2461         if (fl4->saddr) {
2462                 rth = ERR_PTR(-EINVAL);
2463                 if (ipv4_is_multicast(fl4->saddr) ||
2464                     ipv4_is_lbcast(fl4->saddr) ||
2465                     ipv4_is_zeronet(fl4->saddr))
2466                         goto out;
2467
2468                 /* I removed check for oif == dev_out->oif here.
2469                    It was wrong for two reasons:
2470                    1. ip_dev_find(net, saddr) can return wrong iface, if saddr
2471                       is assigned to multiple interfaces.
2472                    2. Moreover, we are allowed to send packets with saddr
2473                       of another iface. --ANK
2474                  */
2475
2476                 if (fl4->flowi4_oif == 0 &&
2477                     (ipv4_is_multicast(fl4->daddr) ||
2478                      ipv4_is_lbcast(fl4->daddr))) {
2479                         /* It is equivalent to inet_addr_type(saddr) == RTN_LOCAL */
2480                         dev_out = __ip_dev_find(net, fl4->saddr, false);
2481                         if (!dev_out)
2482                                 goto out;
2483
2484                         /* Special hack: user can direct multicasts
2485                            and limited broadcast via necessary interface
2486                            without fiddling with IP_MULTICAST_IF or IP_PKTINFO.
2487                            This hack is not just for fun, it allows
2488                            vic,vat and friends to work.
2489                            They bind socket to loopback, set ttl to zero
2490                            and expect that it will work.
2491                            From the viewpoint of routing cache they are broken,
2492                            because we are not allowed to build multicast path
2493                            with loopback source addr (look, routing cache
2494                            cannot know, that ttl is zero, so that packet
2495                            will not leave this host and route is valid).
2496                            Luckily, this hack is good workaround.
2497                          */
2498
2499                         fl4->flowi4_oif = dev_out->ifindex;
2500                         goto make_route;
2501                 }
2502
2503                 if (!(fl4->flowi4_flags & FLOWI_FLAG_ANYSRC)) {
2504                         /* It is equivalent to inet_addr_type(saddr) == RTN_LOCAL */
2505                         if (!__ip_dev_find(net, fl4->saddr, false))
2506                                 goto out;
2507                 }
2508         }
2509
2510
2511         if (fl4->flowi4_oif) {
2512                 dev_out = dev_get_by_index_rcu(net, fl4->flowi4_oif);
2513                 rth = ERR_PTR(-ENODEV);
2514                 if (!dev_out)
2515                         goto out;
2516
2517                 /* RACE: Check return value of inet_select_addr instead. */
2518                 if (!(dev_out->flags & IFF_UP) || !__in_dev_get_rcu(dev_out)) {
2519                         rth = ERR_PTR(-ENETUNREACH);
2520                         goto out;
2521                 }
2522                 if (ipv4_is_local_multicast(fl4->daddr) ||
2523                     ipv4_is_lbcast(fl4->daddr) ||
2524                     fl4->flowi4_proto == IPPROTO_IGMP) {
2525                         if (!fl4->saddr)
2526                                 fl4->saddr = inet_select_addr(dev_out, 0,
2527                                                               RT_SCOPE_LINK);
2528                         goto make_route;
2529                 }
2530                 if (!fl4->saddr) {
2531                         if (ipv4_is_multicast(fl4->daddr))
2532                                 fl4->saddr = inet_select_addr(dev_out, 0,
2533                                                               fl4->flowi4_scope);
2534                         else if (!fl4->daddr)
2535                                 fl4->saddr = inet_select_addr(dev_out, 0,
2536                                                               RT_SCOPE_HOST);
2537                 }
2538         }
2539
2540         if (!fl4->daddr) {
2541                 fl4->daddr = fl4->saddr;
2542                 if (!fl4->daddr)
2543                         fl4->daddr = fl4->saddr = htonl(INADDR_LOOPBACK);
2544                 dev_out = net->loopback_dev;
2545                 fl4->flowi4_oif = LOOPBACK_IFINDEX;
2546                 res->type = RTN_LOCAL;
2547                 flags |= RTCF_LOCAL;
2548                 goto make_route;
2549         }
2550
2551         err = fib_lookup(net, fl4, res, 0);
2552         if (err) {
2553                 res->fi = NULL;
2554                 res->table = NULL;
2555                 if (fl4->flowi4_oif &&
2556                     (ipv4_is_multicast(fl4->daddr) ||
2557                     !netif_index_is_l3_master(net, fl4->flowi4_oif))) {
2558                         /* Apparently, routing tables are wrong. Assume,
2559                            that the destination is on link.
2560
2561                            WHY? DW.
2562                            Because we are allowed to send to iface
2563                            even if it has NO routes and NO assigned
2564                            addresses. When oif is specified, routing
2565                            tables are looked up with only one purpose:
2566                            to catch if destination is gatewayed, rather than
2567                            direct. Moreover, if MSG_DONTROUTE is set,
2568                            we send packet, ignoring both routing tables
2569                            and ifaddr state. --ANK
2570
2571
2572                            We could make it even if oif is unknown,
2573                            likely IPv6, but we do not.
2574                          */
2575
2576                         if (fl4->saddr == 0)
2577                                 fl4->saddr = inet_select_addr(dev_out, 0,
2578                                                               RT_SCOPE_LINK);
2579                         res->type = RTN_UNICAST;
2580                         goto make_route;
2581                 }
2582                 rth = ERR_PTR(err);
2583                 goto out;
2584         }
2585
2586         if (res->type == RTN_LOCAL) {
2587                 if (!fl4->saddr) {
2588                         if (res->fi->fib_prefsrc)
2589                                 fl4->saddr = res->fi->fib_prefsrc;
2590                         else
2591                                 fl4->saddr = fl4->daddr;
2592                 }
2593
2594                 /* L3 master device is the loopback for that domain */
2595                 dev_out = l3mdev_master_dev_rcu(FIB_RES_DEV(*res)) ? :
2596                         net->loopback_dev;
2597
2598                 /* make sure orig_oif points to fib result device even
2599                  * though packet rx/tx happens over loopback or l3mdev
2600                  */
2601                 orig_oif = FIB_RES_OIF(*res);
2602
2603                 fl4->flowi4_oif = dev_out->ifindex;
2604                 flags |= RTCF_LOCAL;
2605                 goto make_route;
2606         }
2607
2608         fib_select_path(net, res, fl4, skb);
2609
2610         dev_out = FIB_RES_DEV(*res);
2611         fl4->flowi4_oif = dev_out->ifindex;
2612
2613
2614 make_route:
2615         rth = __mkroute_output(res, fl4, orig_oif, dev_out, flags);
2616
2617 out:
2618         return rth;
2619 }
2620
2621 static struct dst_entry *ipv4_blackhole_dst_check(struct dst_entry *dst, u32 cookie)
2622 {
2623         return NULL;
2624 }
2625
2626 static unsigned int ipv4_blackhole_mtu(const struct dst_entry *dst)
2627 {
2628         unsigned int mtu = dst_metric_raw(dst, RTAX_MTU);
2629
2630         return mtu ? : dst->dev->mtu;
2631 }
2632
2633 static void ipv4_rt_blackhole_update_pmtu(struct dst_entry *dst, struct sock *sk,
2634                                           struct sk_buff *skb, u32 mtu)
2635 {
2636 }
2637
2638 static void ipv4_rt_blackhole_redirect(struct dst_entry *dst, struct sock *sk,
2639                                        struct sk_buff *skb)
2640 {
2641 }
2642
2643 static u32 *ipv4_rt_blackhole_cow_metrics(struct dst_entry *dst,
2644                                           unsigned long old)
2645 {
2646         return NULL;
2647 }
2648
2649 static struct dst_ops ipv4_dst_blackhole_ops = {
2650         .family                 =       AF_INET,
2651         .check                  =       ipv4_blackhole_dst_check,
2652         .mtu                    =       ipv4_blackhole_mtu,
2653         .default_advmss         =       ipv4_default_advmss,
2654         .update_pmtu            =       ipv4_rt_blackhole_update_pmtu,
2655         .redirect               =       ipv4_rt_blackhole_redirect,
2656         .cow_metrics            =       ipv4_rt_blackhole_cow_metrics,
2657         .neigh_lookup           =       ipv4_neigh_lookup,
2658 };
2659
2660 struct dst_entry *ipv4_blackhole_route(struct net *net, struct dst_entry *dst_orig)
2661 {
2662         struct rtable *ort = (struct rtable *) dst_orig;
2663         struct rtable *rt;
2664
2665         rt = dst_alloc(&ipv4_dst_blackhole_ops, NULL, 1, DST_OBSOLETE_DEAD, 0);
2666         if (rt) {
2667                 struct dst_entry *new = &rt->dst;
2668
2669                 new->__use = 1;
2670                 new->input = dst_discard;
2671                 new->output = dst_discard_out;
2672
2673                 new->dev = net->loopback_dev;
2674                 if (new->dev)
2675                         dev_hold(new->dev);
2676
2677                 rt->rt_is_input = ort->rt_is_input;
2678                 rt->rt_iif = ort->rt_iif;
2679                 rt->rt_pmtu = ort->rt_pmtu;
2680                 rt->rt_mtu_locked = ort->rt_mtu_locked;
2681
2682                 rt->rt_genid = rt_genid_ipv4(net);
2683                 rt->rt_flags = ort->rt_flags;
2684                 rt->rt_type = ort->rt_type;
2685                 rt->rt_gw_family = ort->rt_gw_family;
2686                 if (rt->rt_gw_family == AF_INET)
2687                         rt->rt_gw4 = ort->rt_gw4;
2688                 else if (rt->rt_gw_family == AF_INET6)
2689                         rt->rt_gw6 = ort->rt_gw6;
2690
2691                 INIT_LIST_HEAD(&rt->rt_uncached);
2692         }
2693
2694         dst_release(dst_orig);
2695
2696         return rt ? &rt->dst : ERR_PTR(-ENOMEM);
2697 }
2698
2699 struct rtable *ip_route_output_flow(struct net *net, struct flowi4 *flp4,
2700                                     const struct sock *sk)
2701 {
2702         struct rtable *rt = __ip_route_output_key(net, flp4);
2703
2704         if (IS_ERR(rt))
2705                 return rt;
2706
2707         if (flp4->flowi4_proto)
2708                 rt = (struct rtable *)xfrm_lookup_route(net, &rt->dst,
2709                                                         flowi4_to_flowi(flp4),
2710                                                         sk, 0);
2711
2712         return rt;
2713 }
2714 EXPORT_SYMBOL_GPL(ip_route_output_flow);
2715
2716 /* called with rcu_read_lock held */
2717 static int rt_fill_info(struct net *net, __be32 dst, __be32 src,
2718                         struct rtable *rt, u32 table_id, struct flowi4 *fl4,
2719                         struct sk_buff *skb, u32 portid, u32 seq)
2720 {
2721         struct rtmsg *r;
2722         struct nlmsghdr *nlh;
2723         unsigned long expires = 0;
2724         u32 error;
2725         u32 metrics[RTAX_MAX];
2726
2727         nlh = nlmsg_put(skb, portid, seq, RTM_NEWROUTE, sizeof(*r), 0);
2728         if (!nlh)
2729                 return -EMSGSIZE;
2730
2731         r = nlmsg_data(nlh);
2732         r->rtm_family    = AF_INET;
2733         r->rtm_dst_len  = 32;
2734         r->rtm_src_len  = 0;
2735         r->rtm_tos      = fl4 ? fl4->flowi4_tos : 0;
2736         r->rtm_table    = table_id < 256 ? table_id : RT_TABLE_COMPAT;
2737         if (nla_put_u32(skb, RTA_TABLE, table_id))
2738                 goto nla_put_failure;
2739         r->rtm_type     = rt->rt_type;
2740         r->rtm_scope    = RT_SCOPE_UNIVERSE;
2741         r->rtm_protocol = RTPROT_UNSPEC;
2742         r->rtm_flags    = (rt->rt_flags & ~0xFFFF) | RTM_F_CLONED;
2743         if (rt->rt_flags & RTCF_NOTIFY)
2744                 r->rtm_flags |= RTM_F_NOTIFY;
2745         if (IPCB(skb)->flags & IPSKB_DOREDIRECT)
2746                 r->rtm_flags |= RTCF_DOREDIRECT;
2747
2748         if (nla_put_in_addr(skb, RTA_DST, dst))
2749                 goto nla_put_failure;
2750         if (src) {
2751                 r->rtm_src_len = 32;
2752                 if (nla_put_in_addr(skb, RTA_SRC, src))
2753                         goto nla_put_failure;
2754         }
2755         if (rt->dst.dev &&
2756             nla_put_u32(skb, RTA_OIF, rt->dst.dev->ifindex))
2757                 goto nla_put_failure;
2758 #ifdef CONFIG_IP_ROUTE_CLASSID
2759         if (rt->dst.tclassid &&
2760             nla_put_u32(skb, RTA_FLOW, rt->dst.tclassid))
2761                 goto nla_put_failure;
2762 #endif
2763         if (fl4 && !rt_is_input_route(rt) &&
2764             fl4->saddr != src) {
2765                 if (nla_put_in_addr(skb, RTA_PREFSRC, fl4->saddr))
2766                         goto nla_put_failure;
2767         }
2768         if (rt->rt_gw_family == AF_INET &&
2769             nla_put_in_addr(skb, RTA_GATEWAY, rt->rt_gw4)) {
2770                 goto nla_put_failure;
2771         } else if (rt->rt_gw_family == AF_INET6) {
2772                 int alen = sizeof(struct in6_addr);
2773                 struct nlattr *nla;
2774                 struct rtvia *via;
2775
2776                 nla = nla_reserve(skb, RTA_VIA, alen + 2);
2777                 if (!nla)
2778                         goto nla_put_failure;
2779
2780                 via = nla_data(nla);
2781                 via->rtvia_family = AF_INET6;
2782                 memcpy(via->rtvia_addr, &rt->rt_gw6, alen);
2783         }
2784
2785         expires = rt->dst.expires;
2786         if (expires) {
2787                 unsigned long now = jiffies;
2788
2789                 if (time_before(now, expires))
2790                         expires -= now;
2791                 else
2792                         expires = 0;
2793         }
2794
2795         memcpy(metrics, dst_metrics_ptr(&rt->dst), sizeof(metrics));
2796         if (rt->rt_pmtu && expires)
2797                 metrics[RTAX_MTU - 1] = rt->rt_pmtu;
2798         if (rt->rt_mtu_locked && expires)
2799                 metrics[RTAX_LOCK - 1] |= BIT(RTAX_MTU);
2800         if (rtnetlink_put_metrics(skb, metrics) < 0)
2801                 goto nla_put_failure;
2802
2803         if (fl4) {
2804                 if (fl4->flowi4_mark &&
2805                     nla_put_u32(skb, RTA_MARK, fl4->flowi4_mark))
2806                         goto nla_put_failure;
2807
2808                 if (!uid_eq(fl4->flowi4_uid, INVALID_UID) &&
2809                     nla_put_u32(skb, RTA_UID,
2810                                 from_kuid_munged(current_user_ns(),
2811                                                  fl4->flowi4_uid)))
2812                         goto nla_put_failure;
2813
2814                 if (rt_is_input_route(rt)) {
2815 #ifdef CONFIG_IP_MROUTE
2816                         if (ipv4_is_multicast(dst) &&
2817                             !ipv4_is_local_multicast(dst) &&
2818                             IPV4_DEVCONF_ALL(net, MC_FORWARDING)) {
2819                                 int err = ipmr_get_route(net, skb,
2820                                                          fl4->saddr, fl4->daddr,
2821                                                          r, portid);
2822
2823                                 if (err <= 0) {
2824                                         if (err == 0)
2825                                                 return 0;
2826                                         goto nla_put_failure;
2827                                 }
2828                         } else
2829 #endif
2830                                 if (nla_put_u32(skb, RTA_IIF, fl4->flowi4_iif))
2831                                         goto nla_put_failure;
2832                 }
2833         }
2834
2835         error = rt->dst.error;
2836
2837         if (rtnl_put_cacheinfo(skb, &rt->dst, 0, expires, error) < 0)
2838                 goto nla_put_failure;
2839
2840         nlmsg_end(skb, nlh);
2841         return 0;
2842
2843 nla_put_failure:
2844         nlmsg_cancel(skb, nlh);
2845         return -EMSGSIZE;
2846 }
2847
2848 static int fnhe_dump_bucket(struct net *net, struct sk_buff *skb,
2849                             struct netlink_callback *cb, u32 table_id,
2850                             struct fnhe_hash_bucket *bucket, int genid,
2851                             int *fa_index, int fa_start)
2852 {
2853         int i;
2854
2855         for (i = 0; i < FNHE_HASH_SIZE; i++) {
2856                 struct fib_nh_exception *fnhe;
2857
2858                 for (fnhe = rcu_dereference(bucket[i].chain); fnhe;
2859                      fnhe = rcu_dereference(fnhe->fnhe_next)) {
2860                         struct rtable *rt;
2861                         int err;
2862
2863                         if (*fa_index < fa_start)
2864                                 goto next;
2865
2866                         if (fnhe->fnhe_genid != genid)
2867                                 goto next;
2868
2869                         if (fnhe->fnhe_expires &&
2870                             time_after(jiffies, fnhe->fnhe_expires))
2871                                 goto next;
2872
2873                         rt = rcu_dereference(fnhe->fnhe_rth_input);
2874                         if (!rt)
2875                                 rt = rcu_dereference(fnhe->fnhe_rth_output);
2876                         if (!rt)
2877                                 goto next;
2878
2879                         err = rt_fill_info(net, fnhe->fnhe_daddr, 0, rt,
2880                                            table_id, NULL, skb,
2881                                            NETLINK_CB(cb->skb).portid,
2882                                            cb->nlh->nlmsg_seq);
2883                         if (err)
2884                                 return err;
2885 next:
2886                         (*fa_index)++;
2887                 }
2888         }
2889
2890         return 0;
2891 }
2892
2893 int fib_dump_info_fnhe(struct sk_buff *skb, struct netlink_callback *cb,
2894                        u32 table_id, struct fib_info *fi,
2895                        int *fa_index, int fa_start)
2896 {
2897         struct net *net = sock_net(cb->skb->sk);
2898         int nhsel, genid = fnhe_genid(net);
2899
2900         for (nhsel = 0; nhsel < fib_info_num_path(fi); nhsel++) {
2901                 struct fib_nh_common *nhc = fib_info_nhc(fi, nhsel);
2902                 struct fnhe_hash_bucket *bucket;
2903                 int err;
2904
2905                 if (nhc->nhc_flags & RTNH_F_DEAD)
2906                         continue;
2907
2908                 rcu_read_lock();
2909                 bucket = rcu_dereference(nhc->nhc_exceptions);
2910                 err = 0;
2911                 if (bucket)
2912                         err = fnhe_dump_bucket(net, skb, cb, table_id, bucket,
2913                                                genid, fa_index, fa_start);
2914                 rcu_read_unlock();
2915                 if (err)
2916                         return err;
2917         }
2918
2919         return 0;
2920 }
2921
2922 static struct sk_buff *inet_rtm_getroute_build_skb(__be32 src, __be32 dst,
2923                                                    u8 ip_proto, __be16 sport,
2924                                                    __be16 dport)
2925 {
2926         struct sk_buff *skb;
2927         struct iphdr *iph;
2928
2929         skb = alloc_skb(NLMSG_GOODSIZE, GFP_KERNEL);
2930         if (!skb)
2931                 return NULL;
2932
2933         /* Reserve room for dummy headers, this skb can pass
2934          * through good chunk of routing engine.
2935          */
2936         skb_reset_mac_header(skb);
2937         skb_reset_network_header(skb);
2938         skb->protocol = htons(ETH_P_IP);
2939         iph = skb_put(skb, sizeof(struct iphdr));
2940         iph->protocol = ip_proto;
2941         iph->saddr = src;
2942         iph->daddr = dst;
2943         iph->version = 0x4;
2944         iph->frag_off = 0;
2945         iph->ihl = 0x5;
2946         skb_set_transport_header(skb, skb->len);
2947
2948         switch (iph->protocol) {
2949         case IPPROTO_UDP: {
2950                 struct udphdr *udph;
2951
2952                 udph = skb_put_zero(skb, sizeof(struct udphdr));
2953                 udph->source = sport;
2954                 udph->dest = dport;
2955                 udph->len = sizeof(struct udphdr);
2956                 udph->check = 0;
2957                 break;
2958         }
2959         case IPPROTO_TCP: {
2960                 struct tcphdr *tcph;
2961
2962                 tcph = skb_put_zero(skb, sizeof(struct tcphdr));
2963                 tcph->source    = sport;
2964                 tcph->dest      = dport;
2965                 tcph->doff      = sizeof(struct tcphdr) / 4;
2966                 tcph->rst = 1;
2967                 tcph->check = ~tcp_v4_check(sizeof(struct tcphdr),
2968                                             src, dst, 0);
2969                 break;
2970         }
2971         case IPPROTO_ICMP: {
2972                 struct icmphdr *icmph;
2973
2974                 icmph = skb_put_zero(skb, sizeof(struct icmphdr));
2975                 icmph->type = ICMP_ECHO;
2976                 icmph->code = 0;
2977         }
2978         }
2979
2980         return skb;
2981 }
2982
2983 static int inet_rtm_valid_getroute_req(struct sk_buff *skb,
2984                                        const struct nlmsghdr *nlh,
2985                                        struct nlattr **tb,
2986                                        struct netlink_ext_ack *extack)
2987 {
2988         struct rtmsg *rtm;
2989         int i, err;
2990
2991         if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*rtm))) {
2992                 NL_SET_ERR_MSG(extack,
2993                                "ipv4: Invalid header for route get request");
2994                 return -EINVAL;
2995         }
2996
2997         if (!netlink_strict_get_check(skb))
2998                 return nlmsg_parse_deprecated(nlh, sizeof(*rtm), tb, RTA_MAX,
2999                                               rtm_ipv4_policy, extack);
3000
3001         rtm = nlmsg_data(nlh);
3002         if ((rtm->rtm_src_len && rtm->rtm_src_len != 32) ||
3003             (rtm->rtm_dst_len && rtm->rtm_dst_len != 32) ||
3004             rtm->rtm_table || rtm->rtm_protocol ||
3005             rtm->rtm_scope || rtm->rtm_type) {
3006                 NL_SET_ERR_MSG(extack, "ipv4: Invalid values in header for route get request");
3007                 return -EINVAL;
3008         }
3009
3010         if (rtm->rtm_flags & ~(RTM_F_NOTIFY |
3011                                RTM_F_LOOKUP_TABLE |
3012                                RTM_F_FIB_MATCH)) {
3013                 NL_SET_ERR_MSG(extack, "ipv4: Unsupported rtm_flags for route get request");
3014                 return -EINVAL;
3015         }
3016
3017         err = nlmsg_parse_deprecated_strict(nlh, sizeof(*rtm), tb, RTA_MAX,
3018                                             rtm_ipv4_policy, extack);
3019         if (err)
3020                 return err;
3021
3022         if ((tb[RTA_SRC] && !rtm->rtm_src_len) ||
3023             (tb[RTA_DST] && !rtm->rtm_dst_len)) {
3024                 NL_SET_ERR_MSG(extack, "ipv4: rtm_src_len and rtm_dst_len must be 32 for IPv4");
3025                 return -EINVAL;
3026         }
3027
3028         for (i = 0; i <= RTA_MAX; i++) {
3029                 if (!tb[i])
3030                         continue;
3031
3032                 switch (i) {
3033                 case RTA_IIF:
3034                 case RTA_OIF:
3035                 case RTA_SRC:
3036                 case RTA_DST:
3037                 case RTA_IP_PROTO:
3038                 case RTA_SPORT:
3039                 case RTA_DPORT:
3040                 case RTA_MARK:
3041                 case RTA_UID:
3042                         break;
3043                 default:
3044                         NL_SET_ERR_MSG(extack, "ipv4: Unsupported attribute in route get request");
3045                         return -EINVAL;
3046                 }
3047         }
3048
3049         return 0;
3050 }
3051
3052 static int inet_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh,
3053                              struct netlink_ext_ack *extack)
3054 {
3055         struct net *net = sock_net(in_skb->sk);
3056         struct nlattr *tb[RTA_MAX+1];
3057         u32 table_id = RT_TABLE_MAIN;
3058         __be16 sport = 0, dport = 0;
3059         struct fib_result res = {};
3060         u8 ip_proto = IPPROTO_UDP;
3061         struct rtable *rt = NULL;
3062         struct sk_buff *skb;
3063         struct rtmsg *rtm;
3064         struct flowi4 fl4 = {};
3065         __be32 dst = 0;
3066         __be32 src = 0;
3067         kuid_t uid;
3068         u32 iif;
3069         int err;
3070         int mark;
3071
3072         err = inet_rtm_valid_getroute_req(in_skb, nlh, tb, extack);
3073         if (err < 0)
3074                 return err;
3075
3076         rtm = nlmsg_data(nlh);
3077         src = tb[RTA_SRC] ? nla_get_in_addr(tb[RTA_SRC]) : 0;
3078         dst = tb[RTA_DST] ? nla_get_in_addr(tb[RTA_DST]) : 0;
3079         iif = tb[RTA_IIF] ? nla_get_u32(tb[RTA_IIF]) : 0;
3080         mark = tb[RTA_MARK] ? nla_get_u32(tb[RTA_MARK]) : 0;
3081         if (tb[RTA_UID])
3082                 uid = make_kuid(current_user_ns(), nla_get_u32(tb[RTA_UID]));
3083         else
3084                 uid = (iif ? INVALID_UID : current_uid());
3085
3086         if (tb[RTA_IP_PROTO]) {
3087                 err = rtm_getroute_parse_ip_proto(tb[RTA_IP_PROTO],
3088                                                   &ip_proto, AF_INET, extack);
3089                 if (err)
3090                         return err;
3091         }
3092
3093         if (tb[RTA_SPORT])
3094                 sport = nla_get_be16(tb[RTA_SPORT]);
3095
3096         if (tb[RTA_DPORT])
3097                 dport = nla_get_be16(tb[RTA_DPORT]);
3098
3099         skb = inet_rtm_getroute_build_skb(src, dst, ip_proto, sport, dport);
3100         if (!skb)
3101                 return -ENOBUFS;
3102
3103         fl4.daddr = dst;
3104         fl4.saddr = src;
3105         fl4.flowi4_tos = rtm->rtm_tos;
3106         fl4.flowi4_oif = tb[RTA_OIF] ? nla_get_u32(tb[RTA_OIF]) : 0;
3107         fl4.flowi4_mark = mark;
3108         fl4.flowi4_uid = uid;
3109         if (sport)
3110                 fl4.fl4_sport = sport;
3111         if (dport)
3112                 fl4.fl4_dport = dport;
3113         fl4.flowi4_proto = ip_proto;
3114
3115         rcu_read_lock();
3116
3117         if (iif) {
3118                 struct net_device *dev;
3119
3120                 dev = dev_get_by_index_rcu(net, iif);
3121                 if (!dev) {
3122                         err = -ENODEV;
3123                         goto errout_rcu;
3124                 }
3125
3126                 fl4.flowi4_iif = iif; /* for rt_fill_info */
3127                 skb->dev        = dev;
3128                 skb->mark       = mark;
3129                 err = ip_route_input_rcu(skb, dst, src, rtm->rtm_tos,
3130                                          dev, &res);
3131
3132                 rt = skb_rtable(skb);
3133                 if (err == 0 && rt->dst.error)
3134                         err = -rt->dst.error;
3135         } else {
3136                 fl4.flowi4_iif = LOOPBACK_IFINDEX;
3137                 skb->dev = net->loopback_dev;
3138                 rt = ip_route_output_key_hash_rcu(net, &fl4, &res, skb);
3139                 err = 0;
3140                 if (IS_ERR(rt))
3141                         err = PTR_ERR(rt);
3142                 else
3143                         skb_dst_set(skb, &rt->dst);
3144         }
3145
3146         if (err)
3147                 goto errout_rcu;
3148
3149         if (rtm->rtm_flags & RTM_F_NOTIFY)
3150                 rt->rt_flags |= RTCF_NOTIFY;
3151
3152         if (rtm->rtm_flags & RTM_F_LOOKUP_TABLE)
3153                 table_id = res.table ? res.table->tb_id : 0;
3154
3155         /* reset skb for netlink reply msg */
3156         skb_trim(skb, 0);
3157         skb_reset_network_header(skb);
3158         skb_reset_transport_header(skb);
3159         skb_reset_mac_header(skb);
3160
3161         if (rtm->rtm_flags & RTM_F_FIB_MATCH) {
3162                 if (!res.fi) {
3163                         err = fib_props[res.type].error;
3164                         if (!err)
3165                                 err = -EHOSTUNREACH;
3166                         goto errout_rcu;
3167                 }
3168                 err = fib_dump_info(skb, NETLINK_CB(in_skb).portid,
3169                                     nlh->nlmsg_seq, RTM_NEWROUTE, table_id,
3170                                     rt->rt_type, res.prefix, res.prefixlen,
3171                                     fl4.flowi4_tos, res.fi, 0);
3172         } else {
3173                 err = rt_fill_info(net, dst, src, rt, table_id, &fl4, skb,
3174                                    NETLINK_CB(in_skb).portid, nlh->nlmsg_seq);
3175         }
3176         if (err < 0)
3177                 goto errout_rcu;
3178
3179         rcu_read_unlock();
3180
3181         err = rtnl_unicast(skb, net, NETLINK_CB(in_skb).portid);
3182
3183 errout_free:
3184         return err;
3185 errout_rcu:
3186         rcu_read_unlock();
3187         kfree_skb(skb);
3188         goto errout_free;
3189 }
3190
3191 void ip_rt_multicast_event(struct in_device *in_dev)
3192 {
3193         rt_cache_flush(dev_net(in_dev->dev));
3194 }
3195
3196 #ifdef CONFIG_SYSCTL
3197 static int ip_rt_gc_interval __read_mostly  = 60 * HZ;
3198 static int ip_rt_gc_min_interval __read_mostly  = HZ / 2;
3199 static int ip_rt_gc_elasticity __read_mostly    = 8;
3200 static int ip_min_valid_pmtu __read_mostly      = IPV4_MIN_MTU;
3201
3202 static int ipv4_sysctl_rtcache_flush(struct ctl_table *__ctl, int write,
3203                                         void __user *buffer,
3204                                         size_t *lenp, loff_t *ppos)
3205 {
3206         struct net *net = (struct net *)__ctl->extra1;
3207
3208         if (write) {
3209                 rt_cache_flush(net);
3210                 fnhe_genid_bump(net);
3211                 return 0;
3212         }
3213
3214         return -EINVAL;
3215 }
3216
3217 static struct ctl_table ipv4_route_table[] = {
3218         {
3219                 .procname       = "gc_thresh",
3220                 .data           = &ipv4_dst_ops.gc_thresh,
3221                 .maxlen         = sizeof(int),
3222                 .mode           = 0644,
3223                 .proc_handler   = proc_dointvec,
3224         },
3225         {
3226                 .procname       = "max_size",
3227                 .data           = &ip_rt_max_size,
3228                 .maxlen         = sizeof(int),
3229                 .mode           = 0644,
3230                 .proc_handler   = proc_dointvec,
3231         },
3232         {
3233                 /*  Deprecated. Use gc_min_interval_ms */
3234
3235                 .procname       = "gc_min_interval",
3236                 .data           = &ip_rt_gc_min_interval,
3237                 .maxlen         = sizeof(int),
3238                 .mode           = 0644,
3239                 .proc_handler   = proc_dointvec_jiffies,
3240         },
3241         {
3242                 .procname       = "gc_min_interval_ms",
3243                 .data           = &ip_rt_gc_min_interval,
3244                 .maxlen         = sizeof(int),
3245                 .mode           = 0644,
3246                 .proc_handler   = proc_dointvec_ms_jiffies,
3247         },
3248         {
3249                 .procname       = "gc_timeout",
3250                 .data           = &ip_rt_gc_timeout,
3251                 .maxlen         = sizeof(int),
3252                 .mode           = 0644,
3253                 .proc_handler   = proc_dointvec_jiffies,
3254         },
3255         {
3256                 .procname       = "gc_interval",
3257                 .data           = &ip_rt_gc_interval,
3258                 .maxlen         = sizeof(int),
3259                 .mode           = 0644,
3260                 .proc_handler   = proc_dointvec_jiffies,
3261         },
3262         {
3263                 .procname       = "redirect_load",
3264                 .data           = &ip_rt_redirect_load,
3265                 .maxlen         = sizeof(int),
3266                 .mode           = 0644,
3267                 .proc_handler   = proc_dointvec,
3268         },
3269         {
3270                 .procname       = "redirect_number",
3271                 .data           = &ip_rt_redirect_number,
3272                 .maxlen         = sizeof(int),
3273                 .mode           = 0644,
3274                 .proc_handler   = proc_dointvec,
3275         },
3276         {
3277                 .procname       = "redirect_silence",
3278                 .data           = &ip_rt_redirect_silence,
3279                 .maxlen         = sizeof(int),
3280                 .mode           = 0644,
3281                 .proc_handler   = proc_dointvec,
3282         },
3283         {
3284                 .procname       = "error_cost",
3285                 .data           = &ip_rt_error_cost,
3286                 .maxlen         = sizeof(int),
3287                 .mode           = 0644,
3288                 .proc_handler   = proc_dointvec,
3289         },
3290         {
3291                 .procname       = "error_burst",
3292                 .data           = &ip_rt_error_burst,
3293                 .maxlen         = sizeof(int),
3294                 .mode           = 0644,
3295                 .proc_handler   = proc_dointvec,
3296         },
3297         {
3298                 .procname       = "gc_elasticity",
3299                 .data           = &ip_rt_gc_elasticity,
3300                 .maxlen         = sizeof(int),
3301                 .mode           = 0644,
3302                 .proc_handler   = proc_dointvec,
3303         },
3304         {
3305                 .procname       = "mtu_expires",
3306                 .data           = &ip_rt_mtu_expires,
3307                 .maxlen         = sizeof(int),
3308                 .mode           = 0644,
3309                 .proc_handler   = proc_dointvec_jiffies,
3310         },
3311         {
3312                 .procname       = "min_pmtu",
3313                 .data           = &ip_rt_min_pmtu,
3314                 .maxlen         = sizeof(int),
3315                 .mode           = 0644,
3316                 .proc_handler   = proc_dointvec_minmax,
3317                 .extra1         = &ip_min_valid_pmtu,
3318         },
3319         {
3320                 .procname       = "min_adv_mss",
3321                 .data           = &ip_rt_min_advmss,
3322                 .maxlen         = sizeof(int),
3323                 .mode           = 0644,
3324                 .proc_handler   = proc_dointvec,
3325         },
3326         { }
3327 };
3328
3329 static struct ctl_table ipv4_route_flush_table[] = {
3330         {
3331                 .procname       = "flush",
3332                 .maxlen         = sizeof(int),
3333                 .mode           = 0200,
3334                 .proc_handler   = ipv4_sysctl_rtcache_flush,
3335         },
3336         { },
3337 };
3338
3339 static __net_init int sysctl_route_net_init(struct net *net)
3340 {
3341         struct ctl_table *tbl;
3342
3343         tbl = ipv4_route_flush_table;
3344         if (!net_eq(net, &init_net)) {
3345                 tbl = kmemdup(tbl, sizeof(ipv4_route_flush_table), GFP_KERNEL);
3346                 if (!tbl)
3347                         goto err_dup;
3348
3349                 /* Don't export sysctls to unprivileged users */
3350                 if (net->user_ns != &init_user_ns)
3351                         tbl[0].procname = NULL;
3352         }
3353         tbl[0].extra1 = net;
3354
3355         net->ipv4.route_hdr = register_net_sysctl(net, "net/ipv4/route", tbl);
3356         if (!net->ipv4.route_hdr)
3357                 goto err_reg;
3358         return 0;
3359
3360 err_reg:
3361         if (tbl != ipv4_route_flush_table)
3362                 kfree(tbl);
3363 err_dup:
3364         return -ENOMEM;
3365 }
3366
3367 static __net_exit void sysctl_route_net_exit(struct net *net)
3368 {
3369         struct ctl_table *tbl;
3370
3371         tbl = net->ipv4.route_hdr->ctl_table_arg;
3372         unregister_net_sysctl_table(net->ipv4.route_hdr);
3373         BUG_ON(tbl == ipv4_route_flush_table);
3374         kfree(tbl);
3375 }
3376
3377 static __net_initdata struct pernet_operations sysctl_route_ops = {
3378         .init = sysctl_route_net_init,
3379         .exit = sysctl_route_net_exit,
3380 };
3381 #endif
3382
3383 static __net_init int rt_genid_init(struct net *net)
3384 {
3385         atomic_set(&net->ipv4.rt_genid, 0);
3386         atomic_set(&net->fnhe_genid, 0);
3387         atomic_set(&net->ipv4.dev_addr_genid, get_random_int());
3388         return 0;
3389 }
3390
3391 static __net_initdata struct pernet_operations rt_genid_ops = {
3392         .init = rt_genid_init,
3393 };
3394
3395 static int __net_init ipv4_inetpeer_init(struct net *net)
3396 {
3397         struct inet_peer_base *bp = kmalloc(sizeof(*bp), GFP_KERNEL);
3398
3399         if (!bp)
3400                 return -ENOMEM;
3401         inet_peer_base_init(bp);
3402         net->ipv4.peers = bp;
3403         return 0;
3404 }
3405
3406 static void __net_exit ipv4_inetpeer_exit(struct net *net)
3407 {
3408         struct inet_peer_base *bp = net->ipv4.peers;
3409
3410         net->ipv4.peers = NULL;
3411         inetpeer_invalidate_tree(bp);
3412         kfree(bp);
3413 }
3414
3415 static __net_initdata struct pernet_operations ipv4_inetpeer_ops = {
3416         .init   =       ipv4_inetpeer_init,
3417         .exit   =       ipv4_inetpeer_exit,
3418 };
3419
3420 #ifdef CONFIG_IP_ROUTE_CLASSID
3421 struct ip_rt_acct __percpu *ip_rt_acct __read_mostly;
3422 #endif /* CONFIG_IP_ROUTE_CLASSID */
3423
3424 int __init ip_rt_init(void)
3425 {
3426         int cpu;
3427
3428         ip_idents = kmalloc_array(IP_IDENTS_SZ, sizeof(*ip_idents),
3429                                   GFP_KERNEL);
3430         if (!ip_idents)
3431                 panic("IP: failed to allocate ip_idents\n");
3432
3433         prandom_bytes(ip_idents, IP_IDENTS_SZ * sizeof(*ip_idents));
3434
3435         ip_tstamps = kcalloc(IP_IDENTS_SZ, sizeof(*ip_tstamps), GFP_KERNEL);
3436         if (!ip_tstamps)
3437                 panic("IP: failed to allocate ip_tstamps\n");
3438
3439         for_each_possible_cpu(cpu) {
3440                 struct uncached_list *ul = &per_cpu(rt_uncached_list, cpu);
3441
3442                 INIT_LIST_HEAD(&ul->head);
3443                 spin_lock_init(&ul->lock);
3444         }
3445 #ifdef CONFIG_IP_ROUTE_CLASSID
3446         ip_rt_acct = __alloc_percpu(256 * sizeof(struct ip_rt_acct), __alignof__(struct ip_rt_acct));
3447         if (!ip_rt_acct)
3448                 panic("IP: failed to allocate ip_rt_acct\n");
3449 #endif
3450
3451         ipv4_dst_ops.kmem_cachep =
3452                 kmem_cache_create("ip_dst_cache", sizeof(struct rtable), 0,
3453                                   SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
3454
3455         ipv4_dst_blackhole_ops.kmem_cachep = ipv4_dst_ops.kmem_cachep;
3456
3457         if (dst_entries_init(&ipv4_dst_ops) < 0)
3458                 panic("IP: failed to allocate ipv4_dst_ops counter\n");
3459
3460         if (dst_entries_init(&ipv4_dst_blackhole_ops) < 0)
3461                 panic("IP: failed to allocate ipv4_dst_blackhole_ops counter\n");
3462
3463         ipv4_dst_ops.gc_thresh = ~0;
3464         ip_rt_max_size = INT_MAX;
3465
3466         devinet_init();
3467         ip_fib_init();
3468
3469         if (ip_rt_proc_init())
3470                 pr_err("Unable to create route proc files\n");
3471 #ifdef CONFIG_XFRM
3472         xfrm_init();
3473         xfrm4_init();
3474 #endif
3475         rtnl_register(PF_INET, RTM_GETROUTE, inet_rtm_getroute, NULL,
3476                       RTNL_FLAG_DOIT_UNLOCKED);
3477
3478 #ifdef CONFIG_SYSCTL
3479         register_pernet_subsys(&sysctl_route_ops);
3480 #endif
3481         register_pernet_subsys(&rt_genid_ops);
3482         register_pernet_subsys(&ipv4_inetpeer_ops);
3483         return 0;
3484 }
3485
3486 #ifdef CONFIG_SYSCTL
3487 /*
3488  * We really need to sanitize the damn ipv4 init order, then all
3489  * this nonsense will go away.
3490  */
3491 void __init ip_static_sysctl_init(void)
3492 {
3493         register_net_sysctl(&init_net, "net/ipv4/route", ipv4_route_table);
3494 }
3495 #endif