net/ipv4/route.c

   1 /*
   2  * INET         An implementation of the TCP/IP protocol suite for the LINUX
   3  *              operating system.  INET is implemented using the  BSD Socket
   4  *              interface as the means of communication with the user level.
   5  *
   6  *              ROUTE - implementation of the IP router.
   7  *
   8  * Authors:     Ross Biro
   9  *              Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
  10  *              Alan Cox, <gw4pts@gw4pts.ampr.org>
  11  *              Linus Torvalds, <Linus.Torvalds@helsinki.fi>
  12  *              Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
  13  *
  14  * Fixes:
  15  *              Alan Cox        :       Verify area fixes.
  16  *              Alan Cox        :       cli() protects routing changes
  17  *              Rui Oliveira    :       ICMP routing table updates
  18  *              (rco@di.uminho.pt)      Routing table insertion and update
  19  *              Linus Torvalds  :       Rewrote bits to be sensible
  20  *              Alan Cox        :       Added BSD route gw semantics
  21  *              Alan Cox        :       Super /proc >4K
  22  *              Alan Cox        :       MTU in route table
  23  *              Alan Cox        :       MSS actually. Also added the window
  24  *                                      clamper.
  25  *              Sam Lantinga    :       Fixed route matching in rt_del()
  26  *              Alan Cox        :       Routing cache support.
  27  *              Alan Cox        :       Removed compatibility cruft.
  28  *              Alan Cox        :       RTF_REJECT support.
  29  *              Alan Cox        :       TCP irtt support.
  30  *              Jonathan Naylor :       Added Metric support.
  31  *      Miquel van Smoorenburg  :       BSD API fixes.
  32  *      Miquel van Smoorenburg  :       Metrics.
  33  *              Alan Cox        :       Use __u32 properly
  34  *              Alan Cox        :       Aligned routing errors more closely with BSD
  35  *                                      our system is still very different.
  36  *              Alan Cox        :       Faster /proc handling
  37  *      Alexey Kuznetsov        :       Massive rework to support tree based routing,
  38  *                                      routing caches and better behaviour.
  39  *
  40  *              Olaf Erb        :       irtt wasn't being copied right.
  41  *              Bjorn Ekwall    :       Kerneld route support.
  42  *              Alan Cox        :       Multicast fixed (I hope)
  43  *              Pavel Krauz     :       Limited broadcast fixed
  44  *              Mike McLagan    :       Routing by source
  45  *      Alexey Kuznetsov        :       End of old history. Split to fib.c and
  46  *                                      route.c and rewritten from scratch.
  47  *              Andi Kleen      :       Load-limit warning messages.
  48  *      Vitaly E. Lavrov        :       Transparent proxy revived after year coma.
  49  *      Vitaly E. Lavrov        :       Race condition in ip_route_input_slow.
  50  *      Tobias Ringstrom        :       Uninitialized res.type in ip_route_output_slow.
  51  *      Vladimir V. Ivanov      :       IP rule info (flowid) is really useful.
  52  *              Marc Boucher    :       routing by fwmark
  53  *      Robert Olsson           :       Added rt_cache statistics
  54  *      Arnaldo C. Melo         :       Convert proc stuff to seq_file
  55  *      Eric Dumazet            :       hashed spinlocks and rt_check_expire() fixes.
  56  *      Ilia Sotnikov           :       Ignore TOS on PMTUD and Redirect
  57  *      Ilia Sotnikov           :       Removed TOS from hash calculations
  58  *
  59  *              This program is free software; you can redistribute it and/or
  60  *              modify it under the terms of the GNU General Public License
  61  *              as published by the Free Software Foundation; either version
  62  *              2 of the License, or (at your option) any later version.
  63  */
  64
  65 #define pr_fmt(fmt) "IPv4: " fmt
  66
  67 #include <linux/module.h>
  68 #include <asm/uaccess.h>
  69 #include <linux/bitops.h>
  70 #include <linux/types.h>
  71 #include <linux/kernel.h>
  72 #include <linux/mm.h>
  73 #include <linux/string.h>
  74 #include <linux/socket.h>
  75 #include <linux/sockios.h>
  76 #include <linux/errno.h>
  77 #include <linux/in.h>
  78 #include <linux/inet.h>
  79 #include <linux/netdevice.h>
  80 #include <linux/proc_fs.h>
  81 #include <linux/init.h>
  82 #include <linux/skbuff.h>
  83 #include <linux/inetdevice.h>
  84 #include <linux/igmp.h>
  85 #include <linux/pkt_sched.h>
  86 #include <linux/mroute.h>
  87 #include <linux/netfilter_ipv4.h>
  88 #include <linux/random.h>
  89 #include <linux/rcupdate.h>
  90 #include <linux/times.h>
  91 #include <linux/slab.h>
  92 #include <linux/jhash.h>
  93 #include <net/dst.h>
  94 #include <net/net_namespace.h>
  95 #include <net/protocol.h>
  96 #include <net/ip.h>
  97 #include <net/route.h>
  98 #include <net/inetpeer.h>
  99 #include <net/sock.h>
 100 #include <net/ip_fib.h>
 101 #include <net/arp.h>
 102 #include <net/tcp.h>
 103 #include <net/icmp.h>
 104 #include <net/xfrm.h>
 105 #include <net/netevent.h>
 106 #include <net/rtnetlink.h>
 107 #ifdef CONFIG_SYSCTL
 108 #include <linux/sysctl.h>
 109 #include <linux/kmemleak.h>
 110 #endif
 111 #include <net/secure_seq.h>
 112
 113 #define RT_FL_TOS(oldflp4) \
 114         ((oldflp4)->flowi4_tos & (IPTOS_RT_MASK | RTO_ONLINK))
 115
 116 #define RT_GC_TIMEOUT (300*HZ)
 117
 118 static int ip_rt_max_size;
 119 static int ip_rt_redirect_number __read_mostly  = 9;
 120 static int ip_rt_redirect_load __read_mostly    = HZ / 50;
 121 static int ip_rt_redirect_silence __read_mostly = ((HZ / 50) << (9 + 1));
 122 static int ip_rt_error_cost __read_mostly       = HZ;
 123 static int ip_rt_error_burst __read_mostly      = 5 * HZ;
 124 static int ip_rt_mtu_expires __read_mostly      = 10 * 60 * HZ;
 125 static int ip_rt_min_pmtu __read_mostly         = 512 + 20 + 20;
 126 static int ip_rt_min_advmss __read_mostly       = 256;
 127
 128 /*
 129  *      Interface to generic destination cache.
 130  */
 131
 132 static struct dst_entry *ipv4_dst_check(struct dst_entry *dst, u32 cookie);
 133 static unsigned int      ipv4_default_advmss(const struct dst_entry *dst);
 134 static unsigned int      ipv4_mtu(const struct dst_entry *dst);
 135 static struct dst_entry *ipv4_negative_advice(struct dst_entry *dst);
 136 static void              ipv4_link_failure(struct sk_buff *skb);
 137 static void              ip_rt_update_pmtu(struct dst_entry *dst, struct sock *sk,
 138                                            struct sk_buff *skb, u32 mtu);
 139 static void              ip_do_redirect(struct dst_entry *dst, struct sock *sk,
 140                                         struct sk_buff *skb);
 141 static void             ipv4_dst_destroy(struct dst_entry *dst);
 142
 143 static u32 *ipv4_cow_metrics(struct dst_entry *dst, unsigned long old)
 144 {
 145         WARN_ON(1);
 146         return NULL;
 147 }
 148
 149 static struct neighbour *ipv4_neigh_lookup(const struct dst_entry *dst,
 150                                            struct sk_buff *skb,
 151                                            const void *daddr);
 152
 153 static struct dst_ops ipv4_dst_ops = {
 154         .family =               AF_INET,
 155         .protocol =             cpu_to_be16(ETH_P_IP),
 156         .check =                ipv4_dst_check,
 157         .default_advmss =       ipv4_default_advmss,
 158         .mtu =                  ipv4_mtu,
 159         .cow_metrics =          ipv4_cow_metrics,
 160         .destroy =              ipv4_dst_destroy,
 161         .negative_advice =      ipv4_negative_advice,
 162         .link_failure =         ipv4_link_failure,
 163         .update_pmtu =          ip_rt_update_pmtu,
 164         .redirect =             ip_do_redirect,
 165         .local_out =            __ip_local_out,
 166         .neigh_lookup =         ipv4_neigh_lookup,
 167 };
 168
 169 #define ECN_OR_COST(class)      TC_PRIO_##class
 170
 171 const __u8 ip_tos2prio[16] = {
 172         TC_PRIO_BESTEFFORT,
 173         ECN_OR_COST(BESTEFFORT),
 174         TC_PRIO_BESTEFFORT,
 175         ECN_OR_COST(BESTEFFORT),
 176         TC_PRIO_BULK,
 177         ECN_OR_COST(BULK),
 178         TC_PRIO_BULK,
 179         ECN_OR_COST(BULK),
 180         TC_PRIO_INTERACTIVE,
 181         ECN_OR_COST(INTERACTIVE),
 182         TC_PRIO_INTERACTIVE,
 183         ECN_OR_COST(INTERACTIVE),
 184         TC_PRIO_INTERACTIVE_BULK,
 185         ECN_OR_COST(INTERACTIVE_BULK),
 186         TC_PRIO_INTERACTIVE_BULK,
 187         ECN_OR_COST(INTERACTIVE_BULK)
 188 };
 189 EXPORT_SYMBOL(ip_tos2prio);
 190
 191 static DEFINE_PER_CPU(struct rt_cache_stat, rt_cache_stat);
 192 #define RT_CACHE_STAT_INC(field) raw_cpu_inc(rt_cache_stat.field)
 193
 194 #ifdef CONFIG_PROC_FS
 195 static void *rt_cache_seq_start(struct seq_file *seq, loff_t *pos)
 196 {
 197         if (*pos)
 198                 return NULL;
 199         return SEQ_START_TOKEN;
 200 }
 201
 202 static void *rt_cache_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 203 {
 204         ++*pos;
 205         return NULL;
 206 }
 207
 208 static void rt_cache_seq_stop(struct seq_file *seq, void *v)
 209 {
 210 }
 211
 212 static int rt_cache_seq_show(struct seq_file *seq, void *v)
 213 {
 214         if (v == SEQ_START_TOKEN)
 215                 seq_printf(seq, "%-127s\n",
 216                            "Iface\tDestination\tGateway \tFlags\t\tRefCnt\tUse\t"
 217                            "Metric\tSource\t\tMTU\tWindow\tIRTT\tTOS\tHHRef\t"
 218                            "HHUptod\tSpecDst");
 219         return 0;
 220 }
 221
 222 static const struct seq_operations rt_cache_seq_ops = {
 223         .start  = rt_cache_seq_start,
 224         .next   = rt_cache_seq_next,
 225         .stop   = rt_cache_seq_stop,
 226         .show   = rt_cache_seq_show,
 227 };
 228
 229 static int rt_cache_seq_open(struct inode *inode, struct file *file)
 230 {
 231         return seq_open(file, &rt_cache_seq_ops);
 232 }
 233
 234 static const struct file_operations rt_cache_seq_fops = {
 235         .owner   = THIS_MODULE,
 236         .open    = rt_cache_seq_open,
 237         .read    = seq_read,
 238         .llseek  = seq_lseek,
 239         .release = seq_release,
 240 };
 241
 242
 243 static void *rt_cpu_seq_start(struct seq_file *seq, loff_t *pos)
 244 {
 245         int cpu;
 246
 247         if (*pos == 0)
 248                 return SEQ_START_TOKEN;
 249
 250         for (cpu = *pos-1; cpu < nr_cpu_ids; ++cpu) {
 251                 if (!cpu_possible(cpu))
 252                         continue;
 253                 *pos = cpu+1;
 254                 return &per_cpu(rt_cache_stat, cpu);
 255         }
 256         return NULL;
 257 }
 258
 259 static void *rt_cpu_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 260 {
 261         int cpu;
 262
 263         for (cpu = *pos; cpu < nr_cpu_ids; ++cpu) {
 264                 if (!cpu_possible(cpu))
 265                         continue;
 266                 *pos = cpu+1;
 267                 return &per_cpu(rt_cache_stat, cpu);
 268         }
 269         return NULL;
 270
 271 }
 272
 273 static void rt_cpu_seq_stop(struct seq_file *seq, void *v)
 274 {
 275
 276 }
 277
 278 static int rt_cpu_seq_show(struct seq_file *seq, void *v)
 279 {
 280         struct rt_cache_stat *st = v;
 281
 282         if (v == SEQ_START_TOKEN) {
 283                 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");
 284                 return 0;
 285         }
 286
 287         seq_printf(seq,"%08x  %08x %08x %08x %08x %08x %08x %08x "
 288                    " %08x %08x %08x %08x %08x %08x %08x %08x %08x \n",
 289                    dst_entries_get_slow(&ipv4_dst_ops),
 290                    0, /* st->in_hit */
 291                    st->in_slow_tot,
 292                    st->in_slow_mc,
 293                    st->in_no_route,
 294                    st->in_brd,
 295                    st->in_martian_dst,
 296                    st->in_martian_src,
 297
 298                    0, /* st->out_hit */
 299                    st->out_slow_tot,
 300                    st->out_slow_mc,
 301
 302                    0, /* st->gc_total */
 303                    0, /* st->gc_ignored */
 304                    0, /* st->gc_goal_miss */
 305                    0, /* st->gc_dst_overflow */
 306                    0, /* st->in_hlist_search */
 307                    0  /* st->out_hlist_search */
 308                 );
 309         return 0;
 310 }
 311
 312 static const struct seq_operations rt_cpu_seq_ops = {
 313         .start  = rt_cpu_seq_start,
 314         .next   = rt_cpu_seq_next,
 315         .stop   = rt_cpu_seq_stop,
 316         .show   = rt_cpu_seq_show,
 317 };
 318
 319
 320 static int rt_cpu_seq_open(struct inode *inode, struct file *file)
 321 {
 322         return seq_open(file, &rt_cpu_seq_ops);
 323 }
 324
 325 static const struct file_operations rt_cpu_seq_fops = {
 326         .owner   = THIS_MODULE,
 327         .open    = rt_cpu_seq_open,
 328         .read    = seq_read,
 329         .llseek  = seq_lseek,
 330         .release = seq_release,
 331 };
 332
 333 #ifdef CONFIG_IP_ROUTE_CLASSID
 334 static int rt_acct_proc_show(struct seq_file *m, void *v)
 335 {
 336         struct ip_rt_acct *dst, *src;
 337         unsigned int i, j;
 338
 339         dst = kcalloc(256, sizeof(struct ip_rt_acct), GFP_KERNEL);
 340         if (!dst)
 341                 return -ENOMEM;
 342
 343         for_each_possible_cpu(i) {
 344                 src = (struct ip_rt_acct *)per_cpu_ptr(ip_rt_acct, i);
 345                 for (j = 0; j < 256; j++) {
 346                         dst[j].o_bytes   += src[j].o_bytes;
 347                         dst[j].o_packets += src[j].o_packets;
 348                         dst[j].i_bytes   += src[j].i_bytes;
 349                         dst[j].i_packets += src[j].i_packets;
 350                 }
 351         }
 352
 353         seq_write(m, dst, 256 * sizeof(struct ip_rt_acct));
 354         kfree(dst);
 355         return 0;
 356 }
 357
 358 static int rt_acct_proc_open(struct inode *inode, struct file *file)
 359 {
 360         return single_open(file, rt_acct_proc_show, NULL);
 361 }
 362
 363 static const struct file_operations rt_acct_proc_fops = {
 364         .owner          = THIS_MODULE,
 365         .open           = rt_acct_proc_open,
 366         .read           = seq_read,
 367         .llseek         = seq_lseek,
 368         .release        = single_release,
 369 };
 370 #endif
 371
 372 static int __net_init ip_rt_do_proc_init(struct net *net)
 373 {
 374         struct proc_dir_entry *pde;
 375
 376         pde = proc_create("rt_cache", S_IRUGO, net->proc_net,
 377                           &rt_cache_seq_fops);
 378         if (!pde)
 379                 goto err1;
 380
 381         pde = proc_create("rt_cache", S_IRUGO,
 382                           net->proc_net_stat, &rt_cpu_seq_fops);
 383         if (!pde)
 384                 goto err2;
 385
 386 #ifdef CONFIG_IP_ROUTE_CLASSID
 387         pde = proc_create("rt_acct", 0, net->proc_net, &rt_acct_proc_fops);
 388         if (!pde)
 389                 goto err3;
 390 #endif
 391         return 0;
 392
 393 #ifdef CONFIG_IP_ROUTE_CLASSID
 394 err3:
 395         remove_proc_entry("rt_cache", net->proc_net_stat);
 396 #endif
 397 err2:
 398         remove_proc_entry("rt_cache", net->proc_net);
 399 err1:
 400         return -ENOMEM;
 401 }
 402
 403 static void __net_exit ip_rt_do_proc_exit(struct net *net)
 404 {
 405         remove_proc_entry("rt_cache", net->proc_net_stat);
 406         remove_proc_entry("rt_cache", net->proc_net);
 407 #ifdef CONFIG_IP_ROUTE_CLASSID
 408         remove_proc_entry("rt_acct", net->proc_net);
 409 #endif
 410 }
 411
 412 static struct pernet_operations ip_rt_proc_ops __net_initdata =  {
 413         .init = ip_rt_do_proc_init,
 414         .exit = ip_rt_do_proc_exit,
 415 };
 416
 417 static int __init ip_rt_proc_init(void)
 418 {
 419         return register_pernet_subsys(&ip_rt_proc_ops);
 420 }
 421
 422 #else
 423 static inline int ip_rt_proc_init(void)
 424 {
 425         return 0;
 426 }
 427 #endif /* CONFIG_PROC_FS */
 428
 429 static inline bool rt_is_expired(const struct rtable *rth)
 430 {
 431         return rth->rt_genid != rt_genid_ipv4(dev_net(rth->dst.dev));
 432 }
 433
 434 void rt_cache_flush(struct net *net)
 435 {
 436         rt_genid_bump_ipv4(net);
 437 }
 438
 439 static struct neighbour *ipv4_neigh_lookup(const struct dst_entry *dst,
 440                                            struct sk_buff *skb,
 441                                            const void *daddr)
 442 {
 443         struct net_device *dev = dst->dev;
 444         const __be32 *pkey = daddr;
 445         const struct rtable *rt;
 446         struct neighbour *n;
 447
 448         rt = (const struct rtable *) dst;
 449         if (rt->rt_gateway)
 450                 pkey = (const __be32 *) &rt->rt_gateway;
 451         else if (skb)
 452                 pkey = &ip_hdr(skb)->daddr;
 453
 454         n = __ipv4_neigh_lookup(dev, *(__force u32 *)pkey);
 455         if (n)
 456                 return n;
 457         return neigh_create(&arp_tbl, pkey, dev);
 458 }
 459
 460 #define IP_IDENTS_SZ 2048u
 461 struct ip_ident_bucket {
 462         atomic_t        id;
 463         u32             stamp32;
 464 };
 465
 466 static struct ip_ident_bucket *ip_idents __read_mostly;
 467
 468 /* In order to protect privacy, we add a perturbation to identifiers
 469  * if one generator is seldom used. This makes hard for an attacker
 470  * to infer how many packets were sent between two points in time.
 471  */
 472 u32 ip_idents_reserve(u32 hash, int segs)
 473 {
 474         struct ip_ident_bucket *bucket = ip_idents + hash % IP_IDENTS_SZ;
 475         u32 old = ACCESS_ONCE(bucket->stamp32);
 476         u32 now = (u32)jiffies;
 477         u32 delta = 0;
 478
 479         if (old != now && cmpxchg(&bucket->stamp32, old, now) == old)
 480                 delta = prandom_u32_max(now - old);
 481
 482         return atomic_add_return(segs + delta, &bucket->id) - segs;
 483 }
 484 EXPORT_SYMBOL(ip_idents_reserve);
 485
 486 void __ip_select_ident(struct iphdr *iph, int segs)
 487 {
 488         static u32 ip_idents_hashrnd __read_mostly;
 489         u32 hash, id;
 490
 491         net_get_random_once(&ip_idents_hashrnd, sizeof(ip_idents_hashrnd));
 492
 493         hash = jhash_3words((__force u32)iph->daddr,
 494                             (__force u32)iph->saddr,
 495                             iph->protocol,
 496                             ip_idents_hashrnd);
 497         id = ip_idents_reserve(hash, segs);
 498         iph->id = htons(id);
 499 }
 500 EXPORT_SYMBOL(__ip_select_ident);
 501
 502 static void __build_flow_key(struct flowi4 *fl4, const struct sock *sk,
 503                              const struct iphdr *iph,
 504                              int oif, u8 tos,
 505                              u8 prot, u32 mark, int flow_flags)
 506 {
 507         if (sk) {
 508                 const struct inet_sock *inet = inet_sk(sk);
 509
 510                 oif = sk->sk_bound_dev_if;
 511                 mark = sk->sk_mark;
 512                 tos = RT_CONN_FLAGS(sk);
 513                 prot = inet->hdrincl ? IPPROTO_RAW : sk->sk_protocol;
 514         }
 515         flowi4_init_output(fl4, oif, mark, tos,
 516                            RT_SCOPE_UNIVERSE, prot,
 517                            flow_flags,
 518                            iph->daddr, iph->saddr, 0, 0);
 519 }
 520
 521 static void build_skb_flow_key(struct flowi4 *fl4, const struct sk_buff *skb,
 522                                const struct sock *sk)
 523 {
 524         const struct iphdr *iph = ip_hdr(skb);
 525         int oif = skb->dev->ifindex;
 526         u8 tos = RT_TOS(iph->tos);
 527         u8 prot = iph->protocol;
 528         u32 mark = skb->mark;
 529
 530         __build_flow_key(fl4, sk, iph, oif, tos, prot, mark, 0);
 531 }
 532
 533 static void build_sk_flow_key(struct flowi4 *fl4, const struct sock *sk)
 534 {
 535         const struct inet_sock *inet = inet_sk(sk);
 536         const struct ip_options_rcu *inet_opt;
 537         __be32 daddr = inet->inet_daddr;
 538
 539         rcu_read_lock();
 540         inet_opt = rcu_dereference(inet->inet_opt);
 541         if (inet_opt && inet_opt->opt.srr)
 542                 daddr = inet_opt->opt.faddr;
 543         flowi4_init_output(fl4, sk->sk_bound_dev_if, sk->sk_mark,
 544                            RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE,
 545                            inet->hdrincl ? IPPROTO_RAW : sk->sk_protocol,
 546                            inet_sk_flowi_flags(sk),
 547                            daddr, inet->inet_saddr, 0, 0);
 548         rcu_read_unlock();
 549 }
 550
 551 static void ip_rt_build_flow_key(struct flowi4 *fl4, const struct sock *sk,
 552                                  const struct sk_buff *skb)
 553 {
 554         if (skb)
 555                 build_skb_flow_key(fl4, skb, sk);
 556         else
 557                 build_sk_flow_key(fl4, sk);
 558 }
 559
 560 static inline void rt_free(struct rtable *rt)
 561 {
 562         call_rcu(&rt->dst.rcu_head, dst_rcu_free);
 563 }
 564
 565 static DEFINE_SPINLOCK(fnhe_lock);
 566
 567 static void fnhe_flush_routes(struct fib_nh_exception *fnhe)
 568 {
 569         struct rtable *rt;
 570
 571         rt = rcu_dereference(fnhe->fnhe_rth_input);
 572         if (rt) {
 573                 RCU_INIT_POINTER(fnhe->fnhe_rth_input, NULL);
 574                 rt_free(rt);
 575         }
 576         rt = rcu_dereference(fnhe->fnhe_rth_output);
 577         if (rt) {
 578                 RCU_INIT_POINTER(fnhe->fnhe_rth_output, NULL);
 579                 rt_free(rt);
 580         }
 581 }
 582
 583 static struct fib_nh_exception *fnhe_oldest(struct fnhe_hash_bucket *hash)
 584 {
 585         struct fib_nh_exception *fnhe, *oldest;
 586
 587         oldest = rcu_dereference(hash->chain);
 588         for (fnhe = rcu_dereference(oldest->fnhe_next); fnhe;
 589              fnhe = rcu_dereference(fnhe->fnhe_next)) {
 590                 if (time_before(fnhe->fnhe_stamp, oldest->fnhe_stamp))
 591                         oldest = fnhe;
 592         }
 593         fnhe_flush_routes(oldest);
 594         return oldest;
 595 }
 596
 597 static inline u32 fnhe_hashfun(__be32 daddr)
 598 {
 599         u32 hval;
 600
 601         hval = (__force u32) daddr;
 602         hval ^= (hval >> 11) ^ (hval >> 22);
 603
 604         return hval & (FNHE_HASH_SIZE - 1);
 605 }
 606
 607 static void fill_route_from_fnhe(struct rtable *rt, struct fib_nh_exception *fnhe)
 608 {
 609         rt->rt_pmtu = fnhe->fnhe_pmtu;
 610         rt->dst.expires = fnhe->fnhe_expires;
 611
 612         if (fnhe->fnhe_gw) {
 613                 rt->rt_flags |= RTCF_REDIRECTED;
 614                 rt->rt_gateway = fnhe->fnhe_gw;
 615                 rt->rt_uses_gateway = 1;
 616         }
 617 }
 618
 619 static void update_or_create_fnhe(struct fib_nh *nh, __be32 daddr, __be32 gw,
 620                                   u32 pmtu, unsigned long expires)
 621 {
 622         struct fnhe_hash_bucket *hash;
 623         struct fib_nh_exception *fnhe;
 624         struct rtable *rt;
 625         unsigned int i;
 626         int depth;
 627         u32 hval = fnhe_hashfun(daddr);
 628
 629         spin_lock_bh(&fnhe_lock);
 630
 631         hash = nh->nh_exceptions;
 632         if (!hash) {
 633                 hash = kzalloc(FNHE_HASH_SIZE * sizeof(*hash), GFP_ATOMIC);
 634                 if (!hash)
 635                         goto out_unlock;
 636                 nh->nh_exceptions = hash;
 637         }
 638
 639         hash += hval;
 640
 641         depth = 0;
 642         for (fnhe = rcu_dereference(hash->chain); fnhe;
 643              fnhe = rcu_dereference(fnhe->fnhe_next)) {
 644                 if (fnhe->fnhe_daddr == daddr)
 645                         break;
 646                 depth++;
 647         }
 648
 649         if (fnhe) {
 650                 if (gw)
 651                         fnhe->fnhe_gw = gw;
 652                 if (pmtu) {
 653                         fnhe->fnhe_pmtu = pmtu;
 654                         fnhe->fnhe_expires = max(1UL, expires);
 655                 }
 656                 /* Update all cached dsts too */
 657                 rt = rcu_dereference(fnhe->fnhe_rth_input);
 658                 if (rt)
 659                         fill_route_from_fnhe(rt, fnhe);
 660                 rt = rcu_dereference(fnhe->fnhe_rth_output);
 661                 if (rt)
 662                         fill_route_from_fnhe(rt, fnhe);
 663         } else {
 664                 if (depth > FNHE_RECLAIM_DEPTH)
 665                         fnhe = fnhe_oldest(hash);
 666                 else {
 667                         fnhe = kzalloc(sizeof(*fnhe), GFP_ATOMIC);
 668                         if (!fnhe)
 669                                 goto out_unlock;
 670
 671                         fnhe->fnhe_next = hash->chain;
 672                         rcu_assign_pointer(hash->chain, fnhe);
 673                 }
 674                 fnhe->fnhe_genid = fnhe_genid(dev_net(nh->nh_dev));
 675                 fnhe->fnhe_daddr = daddr;
 676                 fnhe->fnhe_gw = gw;
 677                 fnhe->fnhe_pmtu = pmtu;
 678                 fnhe->fnhe_expires = expires;
 679
 680                 /* Exception created; mark the cached routes for the nexthop
 681                  * stale, so anyone caching it rechecks if this exception
 682                  * applies to them.
 683                  */
 684                 rt = rcu_dereference(nh->nh_rth_input);
 685                 if (rt)
 686                         rt->dst.obsolete = DST_OBSOLETE_KILL;
 687
 688                 for_each_possible_cpu(i) {
 689                         struct rtable __rcu **prt;
 690                         prt = per_cpu_ptr(nh->nh_pcpu_rth_output, i);
 691                         rt = rcu_dereference(*prt);
 692                         if (rt)
 693                                 rt->dst.obsolete = DST_OBSOLETE_KILL;
 694                 }
 695         }
 696
 697         fnhe->fnhe_stamp = jiffies;
 698
 699 out_unlock:
 700         spin_unlock_bh(&fnhe_lock);
 701 }
 702
 703 static void __ip_do_redirect(struct rtable *rt, struct sk_buff *skb, struct flowi4 *fl4,
 704                              bool kill_route)
 705 {
 706         __be32 new_gw = icmp_hdr(skb)->un.gateway;
 707         __be32 old_gw = ip_hdr(skb)->saddr;
 708         struct net_device *dev = skb->dev;
 709         struct in_device *in_dev;
 710         struct fib_result res;
 711         struct neighbour *n;
 712         struct net *net;
 713
 714         switch (icmp_hdr(skb)->code & 7) {
 715         case ICMP_REDIR_NET:
 716         case ICMP_REDIR_NETTOS:
 717         case ICMP_REDIR_HOST:
 718         case ICMP_REDIR_HOSTTOS:
 719                 break;
 720
 721         default:
 722                 return;
 723         }
 724
 725         if (rt->rt_gateway != old_gw)
 726                 return;
 727
 728         in_dev = __in_dev_get_rcu(dev);
 729         if (!in_dev)
 730                 return;
 731
 732         net = dev_net(dev);
 733         if (new_gw == old_gw || !IN_DEV_RX_REDIRECTS(in_dev) ||
 734             ipv4_is_multicast(new_gw) || ipv4_is_lbcast(new_gw) ||
 735             ipv4_is_zeronet(new_gw))
 736                 goto reject_redirect;
 737
 738         if (!IN_DEV_SHARED_MEDIA(in_dev)) {
 739                 if (!inet_addr_onlink(in_dev, new_gw, old_gw))
 740                         goto reject_redirect;
 741                 if (IN_DEV_SEC_REDIRECTS(in_dev) && ip_fib_check_default(new_gw, dev))
 742                         goto reject_redirect;
 743         } else {
 744                 if (inet_addr_type(net, new_gw) != RTN_UNICAST)
 745                         goto reject_redirect;
 746         }
 747
 748         n = ipv4_neigh_lookup(&rt->dst, NULL, &new_gw);
 749         if (n) {
 750                 if (!(n->nud_state & NUD_VALID)) {
 751                         neigh_event_send(n, NULL);
 752                 } else {
 753                         if (fib_lookup(net, fl4, &res) == 0) {
 754                                 struct fib_nh *nh = &FIB_RES_NH(res);
 755
 756                                 update_or_create_fnhe(nh, fl4->daddr, new_gw,
 757                                                       0, 0);
 758                         }
 759                         if (kill_route)
 760                                 rt->dst.obsolete = DST_OBSOLETE_KILL;
 761                         call_netevent_notifiers(NETEVENT_NEIGH_UPDATE, n);
 762                 }
 763                 neigh_release(n);
 764         }
 765         return;
 766
 767 reject_redirect:
 768 #ifdef CONFIG_IP_ROUTE_VERBOSE
 769         if (IN_DEV_LOG_MARTIANS(in_dev)) {
 770                 const struct iphdr *iph = (const struct iphdr *) skb->data;
 771                 __be32 daddr = iph->daddr;
 772                 __be32 saddr = iph->saddr;
 773
 774                 net_info_ratelimited("Redirect from %pI4 on %s about %pI4 ignored\n"
 775                                      "  Advised path = %pI4 -> %pI4\n",
 776                                      &old_gw, dev->name, &new_gw,
 777                                      &saddr, &daddr);
 778         }
 779 #endif
 780         ;
 781 }
 782
 783 static void ip_do_redirect(struct dst_entry *dst, struct sock *sk, struct sk_buff *skb)
 784 {
 785         struct rtable *rt;
 786         struct flowi4 fl4;
 787         const struct iphdr *iph = (const struct iphdr *) skb->data;
 788         int oif = skb->dev->ifindex;
 789         u8 tos = RT_TOS(iph->tos);
 790         u8 prot = iph->protocol;
 791         u32 mark = skb->mark;
 792
 793         rt = (struct rtable *) dst;
 794
 795         __build_flow_key(&fl4, sk, iph, oif, tos, prot, mark, 0);
 796         __ip_do_redirect(rt, skb, &fl4, true);
 797 }
 798
 799 static struct dst_entry *ipv4_negative_advice(struct dst_entry *dst)
 800 {
 801         struct rtable *rt = (struct rtable *)dst;
 802         struct dst_entry *ret = dst;
 803
 804         if (rt) {
 805                 if (dst->obsolete > 0) {
 806                         ip_rt_put(rt);
 807                         ret = NULL;
 808                 } else if ((rt->rt_flags & RTCF_REDIRECTED) ||
 809                            rt->dst.expires) {
 810                         ip_rt_put(rt);
 811                         ret = NULL;
 812                 }
 813         }
 814         return ret;
 815 }
 816
 817 /*
 818  * Algorithm:
 819  *      1. The first ip_rt_redirect_number redirects are sent
 820  *         with exponential backoff, then we stop sending them at all,
 821  *         assuming that the host ignores our redirects.
 822  *      2. If we did not see packets requiring redirects
 823  *         during ip_rt_redirect_silence, we assume that the host
 824  *         forgot redirected route and start to send redirects again.
 825  *
 826  * This algorithm is much cheaper and more intelligent than dumb load limiting
 827  * in icmp.c.
 828  *
 829  * NOTE. Do not forget to inhibit load limiting for redirects (redundant)
 830  * and "frag. need" (breaks PMTU discovery) in icmp.c.
 831  */
 832
 833 void ip_rt_send_redirect(struct sk_buff *skb)
 834 {
 835         struct rtable *rt = skb_rtable(skb);
 836         struct in_device *in_dev;
 837         struct inet_peer *peer;
 838         struct net *net;
 839         int log_martians;
 840
 841         rcu_read_lock();
 842         in_dev = __in_dev_get_rcu(rt->dst.dev);
 843         if (!in_dev || !IN_DEV_TX_REDIRECTS(in_dev)) {
 844                 rcu_read_unlock();
 845                 return;
 846         }
 847         log_martians = IN_DEV_LOG_MARTIANS(in_dev);
 848         rcu_read_unlock();
 849
 850         net = dev_net(rt->dst.dev);
 851         peer = inet_getpeer_v4(net->ipv4.peers, ip_hdr(skb)->saddr, 1);
 852         if (!peer) {
 853                 icmp_send(skb, ICMP_REDIRECT, ICMP_REDIR_HOST,
 854                           rt_nexthop(rt, ip_hdr(skb)->daddr));
 855                 return;
 856         }
 857
 858         /* No redirected packets during ip_rt_redirect_silence;
 859          * reset the algorithm.
 860          */
 861         if (time_after(jiffies, peer->rate_last + ip_rt_redirect_silence))
 862                 peer->rate_tokens = 0;
 863
 864         /* Too many ignored redirects; do not send anything
 865          * set dst.rate_last to the last seen redirected packet.
 866          */
 867         if (peer->rate_tokens >= ip_rt_redirect_number) {
 868                 peer->rate_last = jiffies;
 869                 goto out_put_peer;
 870         }
 871
 872         /* Check for load limit; set rate_last to the latest sent
 873          * redirect.
 874          */
 875         if (peer->rate_tokens == 0 ||
 876             time_after(jiffies,
 877                        (peer->rate_last +
 878                         (ip_rt_redirect_load << peer->rate_tokens)))) {
 879                 __be32 gw = rt_nexthop(rt, ip_hdr(skb)->daddr);
 880
 881                 icmp_send(skb, ICMP_REDIRECT, ICMP_REDIR_HOST, gw);
 882                 peer->rate_last = jiffies;
 883                 ++peer->rate_tokens;
 884 #ifdef CONFIG_IP_ROUTE_VERBOSE
 885                 if (log_martians &&
 886                     peer->rate_tokens == ip_rt_redirect_number)
 887                         net_warn_ratelimited("host %pI4/if%d ignores redirects for %pI4 to %pI4\n",
 888                                              &ip_hdr(skb)->saddr, inet_iif(skb),
 889                                              &ip_hdr(skb)->daddr, &gw);
 890 #endif
 891         }
 892 out_put_peer:
 893         inet_putpeer(peer);
 894 }
 895
 896 static int ip_error(struct sk_buff *skb)
 897 {
 898         struct in_device *in_dev = __in_dev_get_rcu(skb->dev);
 899         struct rtable *rt = skb_rtable(skb);
 900         struct inet_peer *peer;
 901         unsigned long now;
 902         struct net *net;
 903         bool send;
 904         int code;
 905
 906         net = dev_net(rt->dst.dev);
 907         if (!IN_DEV_FORWARD(in_dev)) {
 908                 switch (rt->dst.error) {
 909                 case EHOSTUNREACH:
 910                         IP_INC_STATS_BH(net, IPSTATS_MIB_INADDRERRORS);
 911                         break;
 912
 913                 case ENETUNREACH:
 914                         IP_INC_STATS_BH(net, IPSTATS_MIB_INNOROUTES);
 915                         break;
 916                 }
 917                 goto out;
 918         }
 919
 920         switch (rt->dst.error) {
 921         case EINVAL:
 922         default:
 923                 goto out;
 924         case EHOSTUNREACH:
 925                 code = ICMP_HOST_UNREACH;
 926                 break;
 927         case ENETUNREACH:
 928                 code = ICMP_NET_UNREACH;
 929                 IP_INC_STATS_BH(net, IPSTATS_MIB_INNOROUTES);
 930                 break;
 931         case EACCES:
 932                 code = ICMP_PKT_FILTERED;
 933                 break;
 934         }
 935
 936         peer = inet_getpeer_v4(net->ipv4.peers, ip_hdr(skb)->saddr, 1);
 937
 938         send = true;
 939         if (peer) {
 940                 now = jiffies;
 941                 peer->rate_tokens += now - peer->rate_last;
 942                 if (peer->rate_tokens > ip_rt_error_burst)
 943                         peer->rate_tokens = ip_rt_error_burst;
 944                 peer->rate_last = now;
 945                 if (peer->rate_tokens >= ip_rt_error_cost)
 946                         peer->rate_tokens -= ip_rt_error_cost;
 947                 else
 948                         send = false;
 949                 inet_putpeer(peer);
 950         }
 951         if (send)
 952                 icmp_send(skb, ICMP_DEST_UNREACH, code, 0);
 953
 954 out:    kfree_skb(skb);
 955         return 0;
 956 }
 957
 958 static void __ip_rt_update_pmtu(struct rtable *rt, struct flowi4 *fl4, u32 mtu)
 959 {
 960         struct dst_entry *dst = &rt->dst;
 961         struct fib_result res;
 962
 963         if (dst_metric_locked(dst, RTAX_MTU))
 964                 return;
 965
 966         if (dst->dev->mtu < mtu)
 967                 return;
 968
 969         if (mtu < ip_rt_min_pmtu)
 970                 mtu = ip_rt_min_pmtu;
 971
 972         if (rt->rt_pmtu == mtu &&
 973             time_before(jiffies, dst->expires - ip_rt_mtu_expires / 2))
 974                 return;
 975
 976         rcu_read_lock();
 977         if (fib_lookup(dev_net(dst->dev), fl4, &res) == 0) {
 978                 struct fib_nh *nh = &FIB_RES_NH(res);
 979
 980                 update_or_create_fnhe(nh, fl4->daddr, 0, mtu,
 981                                       jiffies + ip_rt_mtu_expires);
 982         }
 983         rcu_read_unlock();
 984 }
 985
 986 static void ip_rt_update_pmtu(struct dst_entry *dst, struct sock *sk,
 987                               struct sk_buff *skb, u32 mtu)
 988 {
 989         struct rtable *rt = (struct rtable *) dst;
 990         struct flowi4 fl4;
 991
 992         ip_rt_build_flow_key(&fl4, sk, skb);
 993         __ip_rt_update_pmtu(rt, &fl4, mtu);
 994 }
 995
 996 void ipv4_update_pmtu(struct sk_buff *skb, struct net *net, u32 mtu,
 997                       int oif, u32 mark, u8 protocol, int flow_flags)
 998 {
 999         const struct iphdr *iph = (const struct iphdr *) skb->data;
1000         struct flowi4 fl4;
1001         struct rtable *rt;
1002
1003         if (!mark)
1004                 mark = IP4_REPLY_MARK(net, skb->mark);
1005
1006         __build_flow_key(&fl4, NULL, iph, oif,
1007                          RT_TOS(iph->tos), protocol, mark, flow_flags);
1008         rt = __ip_route_output_key(net, &fl4);
1009         if (!IS_ERR(rt)) {
1010                 __ip_rt_update_pmtu(rt, &fl4, mtu);
1011                 ip_rt_put(rt);
1012         }
1013 }
1014 EXPORT_SYMBOL_GPL(ipv4_update_pmtu);
1015
1016 static void __ipv4_sk_update_pmtu(struct sk_buff *skb, struct sock *sk, u32 mtu)
1017 {
1018         const struct iphdr *iph = (const struct iphdr *) skb->data;
1019         struct flowi4 fl4;
1020         struct rtable *rt;
1021
1022         __build_flow_key(&fl4, sk, iph, 0, 0, 0, 0, 0);
1023
1024         if (!fl4.flowi4_mark)
1025                 fl4.flowi4_mark = IP4_REPLY_MARK(sock_net(sk), skb->mark);
1026
1027         rt = __ip_route_output_key(sock_net(sk), &fl4);
1028         if (!IS_ERR(rt)) {
1029                 __ip_rt_update_pmtu(rt, &fl4, mtu);
1030                 ip_rt_put(rt);
1031         }
1032 }
1033
1034 void ipv4_sk_update_pmtu(struct sk_buff *skb, struct sock *sk, u32 mtu)
1035 {
1036         const struct iphdr *iph = (const struct iphdr *) skb->data;
1037         struct flowi4 fl4;
1038         struct rtable *rt;
1039         struct dst_entry *odst = NULL;
1040         bool new = false;
1041
1042         bh_lock_sock(sk);
1043
1044         if (!ip_sk_accept_pmtu(sk))
1045                 goto out;
1046
1047         odst = sk_dst_get(sk);
1048
1049         if (sock_owned_by_user(sk) || !odst) {
1050                 __ipv4_sk_update_pmtu(skb, sk, mtu);
1051                 goto out;
1052         }
1053
1054         __build_flow_key(&fl4, sk, iph, 0, 0, 0, 0, 0);
1055
1056         rt = (struct rtable *)odst;
1057         if (odst->obsolete && odst->ops->check(odst, 0) == NULL) {
1058                 rt = ip_route_output_flow(sock_net(sk), &fl4, sk);
1059                 if (IS_ERR(rt))
1060                         goto out;
1061
1062                 new = true;
1063         }
1064
1065         __ip_rt_update_pmtu((struct rtable *) rt->dst.path, &fl4, mtu);
1066
1067         if (!dst_check(&rt->dst, 0)) {
1068                 if (new)
1069                         dst_release(&rt->dst);
1070
1071                 rt = ip_route_output_flow(sock_net(sk), &fl4, sk);
1072                 if (IS_ERR(rt))
1073                         goto out;
1074
1075                 new = true;
1076         }
1077
1078         if (new)
1079                 sk_dst_set(sk, &rt->dst);
1080
1081 out:
1082         bh_unlock_sock(sk);
1083         dst_release(odst);
1084 }
1085 EXPORT_SYMBOL_GPL(ipv4_sk_update_pmtu);
1086
1087 void ipv4_redirect(struct sk_buff *skb, struct net *net,
1088                    int oif, u32 mark, u8 protocol, int flow_flags)
1089 {
1090         const struct iphdr *iph = (const struct iphdr *) skb->data;
1091         struct flowi4 fl4;
1092         struct rtable *rt;
1093
1094         __build_flow_key(&fl4, NULL, iph, oif,
1095                          RT_TOS(iph->tos), protocol, mark, flow_flags);
1096         rt = __ip_route_output_key(net, &fl4);
1097         if (!IS_ERR(rt)) {
1098                 __ip_do_redirect(rt, skb, &fl4, false);
1099                 ip_rt_put(rt);
1100         }
1101 }
1102 EXPORT_SYMBOL_GPL(ipv4_redirect);
1103
1104 void ipv4_sk_redirect(struct sk_buff *skb, struct sock *sk)
1105 {
1106         const struct iphdr *iph = (const struct iphdr *) skb->data;
1107         struct flowi4 fl4;
1108         struct rtable *rt;
1109
1110         __build_flow_key(&fl4, sk, iph, 0, 0, 0, 0, 0);
1111         rt = __ip_route_output_key(sock_net(sk), &fl4);
1112         if (!IS_ERR(rt)) {
1113                 __ip_do_redirect(rt, skb, &fl4, false);
1114                 ip_rt_put(rt);
1115         }
1116 }
1117 EXPORT_SYMBOL_GPL(ipv4_sk_redirect);
1118
1119 static struct dst_entry *ipv4_dst_check(struct dst_entry *dst, u32 cookie)
1120 {
1121         struct rtable *rt = (struct rtable *) dst;
1122
1123         /* All IPV4 dsts are created with ->obsolete set to the value
1124          * DST_OBSOLETE_FORCE_CHK which forces validation calls down
1125          * into this function always.
1126          *
1127          * When a PMTU/redirect information update invalidates a route,
1128          * this is indicated by setting obsolete to DST_OBSOLETE_KILL or
1129          * DST_OBSOLETE_DEAD by dst_free().
1130          */
1131         if (dst->obsolete != DST_OBSOLETE_FORCE_CHK || rt_is_expired(rt))
1132                 return NULL;
1133         return dst;
1134 }
1135
1136 static void ipv4_link_failure(struct sk_buff *skb)
1137 {
1138         struct rtable *rt;
1139
1140         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_HOST_UNREACH, 0);
1141
1142         rt = skb_rtable(skb);
1143         if (rt)
1144                 dst_set_expires(&rt->dst, 0);
1145 }
1146
1147 static int ip_rt_bug(struct sock *sk, struct sk_buff *skb)
1148 {
1149         pr_debug("%s: %pI4 -> %pI4, %s\n",
1150                  __func__, &ip_hdr(skb)->saddr, &ip_hdr(skb)->daddr,
1151                  skb->dev ? skb->dev->name : "?");
1152         kfree_skb(skb);
1153         WARN_ON(1);
1154         return 0;
1155 }
1156
1157 /*
1158    We do not cache source address of outgoing interface,
1159    because it is used only by IP RR, TS and SRR options,
1160    so that it out of fast path.
1161
1162    BTW remember: "addr" is allowed to be not aligned
1163    in IP options!
1164  */
1165
1166 void ip_rt_get_source(u8 *addr, struct sk_buff *skb, struct rtable *rt)
1167 {
1168         __be32 src;
1169
1170         if (rt_is_output_route(rt))
1171                 src = ip_hdr(skb)->saddr;
1172         else {
1173                 struct fib_result res;
1174                 struct flowi4 fl4;
1175                 struct iphdr *iph;
1176
1177                 iph = ip_hdr(skb);
1178
1179                 memset(&fl4, 0, sizeof(fl4));
1180                 fl4.daddr = iph->daddr;
1181                 fl4.saddr = iph->saddr;
1182                 fl4.flowi4_tos = RT_TOS(iph->tos);
1183                 fl4.flowi4_oif = rt->dst.dev->ifindex;
1184                 fl4.flowi4_iif = skb->dev->ifindex;
1185                 fl4.flowi4_mark = skb->mark;
1186
1187                 rcu_read_lock();
1188                 if (fib_lookup(dev_net(rt->dst.dev), &fl4, &res) == 0)
1189                         src = FIB_RES_PREFSRC(dev_net(rt->dst.dev), res);
1190                 else
1191                         src = inet_select_addr(rt->dst.dev,
1192                                                rt_nexthop(rt, iph->daddr),
1193                                                RT_SCOPE_UNIVERSE);
1194                 rcu_read_unlock();
1195         }
1196         memcpy(addr, &src, 4);
1197 }
1198
1199 #ifdef CONFIG_IP_ROUTE_CLASSID
1200 static void set_class_tag(struct rtable *rt, u32 tag)
1201 {
1202         if (!(rt->dst.tclassid & 0xFFFF))
1203                 rt->dst.tclassid |= tag & 0xFFFF;
1204         if (!(rt->dst.tclassid & 0xFFFF0000))
1205                 rt->dst.tclassid |= tag & 0xFFFF0000;
1206 }
1207 #endif
1208
1209 static unsigned int ipv4_default_advmss(const struct dst_entry *dst)
1210 {
1211         unsigned int advmss = dst_metric_raw(dst, RTAX_ADVMSS);
1212
1213         if (advmss == 0) {
1214                 advmss = max_t(unsigned int, dst->dev->mtu - 40,
1215                                ip_rt_min_advmss);
1216                 if (advmss > 65535 - 40)
1217                         advmss = 65535 - 40;
1218         }
1219         return advmss;
1220 }
1221
1222 static unsigned int ipv4_mtu(const struct dst_entry *dst)
1223 {
1224         const struct rtable *rt = (const struct rtable *) dst;
1225         unsigned int mtu = rt->rt_pmtu;
1226
1227         if (!mtu || time_after_eq(jiffies, rt->dst.expires))
1228                 mtu = dst_metric_raw(dst, RTAX_MTU);
1229
1230         if (mtu)
1231                 return mtu;
1232
1233         mtu = dst->dev->mtu;
1234
1235         if (unlikely(dst_metric_locked(dst, RTAX_MTU))) {
1236                 if (rt->rt_uses_gateway && mtu > 576)
1237                         mtu = 576;
1238         }
1239
1240         return min_t(unsigned int, mtu, IP_MAX_MTU);
1241 }
1242
1243 static struct fib_nh_exception *find_exception(struct fib_nh *nh, __be32 daddr)
1244 {
1245         struct fnhe_hash_bucket *hash = nh->nh_exceptions;
1246         struct fib_nh_exception *fnhe;
1247         u32 hval;
1248
1249         if (!hash)
1250                 return NULL;
1251
1252         hval = fnhe_hashfun(daddr);
1253
1254         for (fnhe = rcu_dereference(hash[hval].chain); fnhe;
1255              fnhe = rcu_dereference(fnhe->fnhe_next)) {
1256                 if (fnhe->fnhe_daddr == daddr)
1257                         return fnhe;
1258         }
1259         return NULL;
1260 }
1261
1262 static bool rt_bind_exception(struct rtable *rt, struct fib_nh_exception *fnhe,
1263                               __be32 daddr)
1264 {
1265         bool ret = false;
1266
1267         spin_lock_bh(&fnhe_lock);
1268
1269         if (daddr == fnhe->fnhe_daddr) {
1270                 struct rtable __rcu **porig;
1271                 struct rtable *orig;
1272                 int genid = fnhe_genid(dev_net(rt->dst.dev));
1273
1274                 if (rt_is_input_route(rt))
1275                         porig = &fnhe->fnhe_rth_input;
1276                 else
1277                         porig = &fnhe->fnhe_rth_output;
1278                 orig = rcu_dereference(*porig);
1279
1280                 if (fnhe->fnhe_genid != genid) {
1281                         fnhe->fnhe_genid = genid;
1282                         fnhe->fnhe_gw = 0;
1283                         fnhe->fnhe_pmtu = 0;
1284                         fnhe->fnhe_expires = 0;
1285                         fnhe_flush_routes(fnhe);
1286                         orig = NULL;
1287                 }
1288                 fill_route_from_fnhe(rt, fnhe);
1289                 if (!rt->rt_gateway)
1290                         rt->rt_gateway = daddr;
1291
1292                 if (!(rt->dst.flags & DST_NOCACHE)) {
1293                         rcu_assign_pointer(*porig, rt);
1294                         if (orig)
1295                                 rt_free(orig);
1296                         ret = true;
1297                 }
1298
1299                 fnhe->fnhe_stamp = jiffies;
1300         }
1301         spin_unlock_bh(&fnhe_lock);
1302
1303         return ret;
1304 }
1305
1306 static bool rt_cache_route(struct fib_nh *nh, struct rtable *rt)
1307 {
1308         struct rtable *orig, *prev, **p;
1309         bool ret = true;
1310
1311         if (rt_is_input_route(rt)) {
1312                 p = (struct rtable **)&nh->nh_rth_input;
1313         } else {
1314                 p = (struct rtable **)__this_cpu_ptr(nh->nh_pcpu_rth_output);
1315         }
1316         orig = *p;
1317
1318         prev = cmpxchg(p, orig, rt);
1319         if (prev == orig) {
1320                 if (orig)
1321                         rt_free(orig);
1322         } else
1323                 ret = false;
1324
1325         return ret;
1326 }
1327
1328 static DEFINE_SPINLOCK(rt_uncached_lock);
1329 static LIST_HEAD(rt_uncached_list);
1330
1331 static void rt_add_uncached_list(struct rtable *rt)
1332 {
1333         spin_lock_bh(&rt_uncached_lock);
1334         list_add_tail(&rt->rt_uncached, &rt_uncached_list);
1335         spin_unlock_bh(&rt_uncached_lock);
1336 }
1337
1338 static void ipv4_dst_destroy(struct dst_entry *dst)
1339 {
1340         struct rtable *rt = (struct rtable *) dst;
1341
1342         if (!list_empty(&rt->rt_uncached)) {
1343                 spin_lock_bh(&rt_uncached_lock);
1344                 list_del(&rt->rt_uncached);
1345                 spin_unlock_bh(&rt_uncached_lock);
1346         }
1347 }
1348
1349 void rt_flush_dev(struct net_device *dev)
1350 {
1351         if (!list_empty(&rt_uncached_list)) {
1352                 struct net *net = dev_net(dev);
1353                 struct rtable *rt;
1354
1355                 spin_lock_bh(&rt_uncached_lock);
1356                 list_for_each_entry(rt, &rt_uncached_list, rt_uncached) {
1357                         if (rt->dst.dev != dev)
1358                                 continue;
1359                         rt->dst.dev = net->loopback_dev;
1360                         dev_hold(rt->dst.dev);
1361                         dev_put(dev);
1362                 }
1363                 spin_unlock_bh(&rt_uncached_lock);
1364         }
1365 }
1366
1367 static bool rt_cache_valid(const struct rtable *rt)
1368 {
1369         return  rt &&
1370                 rt->dst.obsolete == DST_OBSOLETE_FORCE_CHK &&
1371                 !rt_is_expired(rt);
1372 }
1373
1374 static void rt_set_nexthop(struct rtable *rt, __be32 daddr,
1375                            const struct fib_result *res,
1376                            struct fib_nh_exception *fnhe,
1377                            struct fib_info *fi, u16 type, u32 itag)
1378 {
1379         bool cached = false;
1380
1381         if (fi) {
1382                 struct fib_nh *nh = &FIB_RES_NH(*res);
1383
1384                 if (nh->nh_gw && nh->nh_scope == RT_SCOPE_LINK) {
1385                         rt->rt_gateway = nh->nh_gw;
1386                         rt->rt_uses_gateway = 1;
1387                 }
1388                 dst_init_metrics(&rt->dst, fi->fib_metrics, true);
1389 #ifdef CONFIG_IP_ROUTE_CLASSID
1390                 rt->dst.tclassid = nh->nh_tclassid;
1391 #endif
1392                 if (unlikely(fnhe))
1393                         cached = rt_bind_exception(rt, fnhe, daddr);
1394                 else if (!(rt->dst.flags & DST_NOCACHE))
1395                         cached = rt_cache_route(nh, rt);
1396                 if (unlikely(!cached)) {
1397                         /* Routes we intend to cache in nexthop exception or
1398                          * FIB nexthop have the DST_NOCACHE bit clear.
1399                          * However, if we are unsuccessful at storing this
1400                          * route into the cache we really need to set it.
1401                          */
1402                         rt->dst.flags |= DST_NOCACHE;
1403                         if (!rt->rt_gateway)
1404                                 rt->rt_gateway = daddr;
1405                         rt_add_uncached_list(rt);
1406                 }
1407         } else
1408                 rt_add_uncached_list(rt);
1409
1410 #ifdef CONFIG_IP_ROUTE_CLASSID
1411 #ifdef CONFIG_IP_MULTIPLE_TABLES
1412         set_class_tag(rt, res->tclassid);
1413 #endif
1414         set_class_tag(rt, itag);
1415 #endif
1416 }
1417
1418 static struct rtable *rt_dst_alloc(struct net_device *dev,
1419                                    bool nopolicy, bool noxfrm, bool will_cache)
1420 {
1421         return dst_alloc(&ipv4_dst_ops, dev, 1, DST_OBSOLETE_FORCE_CHK,
1422                          (will_cache ? 0 : (DST_HOST | DST_NOCACHE)) |
1423                          (nopolicy ? DST_NOPOLICY : 0) |
1424                          (noxfrm ? DST_NOXFRM : 0));
1425 }
1426
1427 /* called in rcu_read_lock() section */
1428 static int ip_route_input_mc(struct sk_buff *skb, __be32 daddr, __be32 saddr,
1429                                 u8 tos, struct net_device *dev, int our)
1430 {
1431         struct rtable *rth;
1432         struct in_device *in_dev = __in_dev_get_rcu(dev);
1433         u32 itag = 0;
1434         int err;
1435
1436         /* Primary sanity checks. */
1437
1438         if (in_dev == NULL)
1439                 return -EINVAL;
1440
1441         if (ipv4_is_multicast(saddr) || ipv4_is_lbcast(saddr) ||
1442             skb->protocol != htons(ETH_P_IP))
1443                 goto e_inval;
1444
1445         if (likely(!IN_DEV_ROUTE_LOCALNET(in_dev)))
1446                 if (ipv4_is_loopback(saddr))
1447                         goto e_inval;
1448
1449         if (ipv4_is_zeronet(saddr)) {
1450                 if (!ipv4_is_local_multicast(daddr))
1451                         goto e_inval;
1452         } else {
1453                 err = fib_validate_source(skb, saddr, 0, tos, 0, dev,
1454                                           in_dev, &itag);
1455                 if (err < 0)
1456                         goto e_err;
1457         }
1458         rth = rt_dst_alloc(dev_net(dev)->loopback_dev,
1459                            IN_DEV_CONF_GET(in_dev, NOPOLICY), false, false);
1460         if (!rth)
1461                 goto e_nobufs;
1462
1463 #ifdef CONFIG_IP_ROUTE_CLASSID
1464         rth->dst.tclassid = itag;
1465 #endif
1466         rth->dst.output = ip_rt_bug;
1467
1468         rth->rt_genid   = rt_genid_ipv4(dev_net(dev));
1469         rth->rt_flags   = RTCF_MULTICAST;
1470         rth->rt_type    = RTN_MULTICAST;
1471         rth->rt_is_input= 1;
1472         rth->rt_iif     = 0;
1473         rth->rt_pmtu    = 0;
1474         rth->rt_gateway = 0;
1475         rth->rt_uses_gateway = 0;
1476         INIT_LIST_HEAD(&rth->rt_uncached);
1477         if (our) {
1478                 rth->dst.input= ip_local_deliver;
1479                 rth->rt_flags |= RTCF_LOCAL;
1480         }
1481
1482 #ifdef CONFIG_IP_MROUTE
1483         if (!ipv4_is_local_multicast(daddr) && IN_DEV_MFORWARD(in_dev))
1484                 rth->dst.input = ip_mr_input;
1485 #endif
1486         RT_CACHE_STAT_INC(in_slow_mc);
1487
1488         skb_dst_set(skb, &rth->dst);
1489         return 0;
1490
1491 e_nobufs:
1492         return -ENOBUFS;
1493 e_inval:
1494         return -EINVAL;
1495 e_err:
1496         return err;
1497 }
1498
1499
1500 static void ip_handle_martian_source(struct net_device *dev,
1501                                      struct in_device *in_dev,
1502                                      struct sk_buff *skb,
1503                                      __be32 daddr,
1504                                      __be32 saddr)
1505 {
1506         RT_CACHE_STAT_INC(in_martian_src);
1507 #ifdef CONFIG_IP_ROUTE_VERBOSE
1508         if (IN_DEV_LOG_MARTIANS(in_dev) && net_ratelimit()) {
1509                 /*
1510                  *      RFC1812 recommendation, if source is martian,
1511                  *      the only hint is MAC header.
1512                  */
1513                 pr_warn("martian source %pI4 from %pI4, on dev %s\n",
1514                         &daddr, &saddr, dev->name);
1515                 if (dev->hard_header_len && skb_mac_header_was_set(skb)) {
1516                         print_hex_dump(KERN_WARNING, "ll header: ",
1517                                        DUMP_PREFIX_OFFSET, 16, 1,
1518                                        skb_mac_header(skb),
1519                                        dev->hard_header_len, true);
1520                 }
1521         }
1522 #endif
1523 }
1524
1525 /* called in rcu_read_lock() section */
1526 static int __mkroute_input(struct sk_buff *skb,
1527                            const struct fib_result *res,
1528                            struct in_device *in_dev,
1529                            __be32 daddr, __be32 saddr, u32 tos)
1530 {
1531         struct fib_nh_exception *fnhe;
1532         struct rtable *rth;
1533         int err;
1534         struct in_device *out_dev;
1535         unsigned int flags = 0;
1536         bool do_cache;
1537         u32 itag = 0;
1538
1539         /* get a working reference to the output device */
1540         out_dev = __in_dev_get_rcu(FIB_RES_DEV(*res));
1541         if (out_dev == NULL) {
1542                 net_crit_ratelimited("Bug in ip_route_input_slow(). Please report.\n");
1543                 return -EINVAL;
1544         }
1545
1546         err = fib_validate_source(skb, saddr, daddr, tos, FIB_RES_OIF(*res),
1547                                   in_dev->dev, in_dev, &itag);
1548         if (err < 0) {
1549                 ip_handle_martian_source(in_dev->dev, in_dev, skb, daddr,
1550                                          saddr);
1551
1552                 goto cleanup;
1553         }
1554
1555         do_cache = res->fi && !itag;
1556         if (out_dev == in_dev && err && IN_DEV_TX_REDIRECTS(out_dev) &&
1557             (IN_DEV_SHARED_MEDIA(out_dev) ||
1558              inet_addr_onlink(out_dev, saddr, FIB_RES_GW(*res)))) {
1559                 flags |= RTCF_DOREDIRECT;
1560                 do_cache = false;
1561         }
1562
1563         if (skb->protocol != htons(ETH_P_IP)) {
1564                 /* Not IP (i.e. ARP). Do not create route, if it is
1565                  * invalid for proxy arp. DNAT routes are always valid.
1566                  *
1567                  * Proxy arp feature have been extended to allow, ARP
1568                  * replies back to the same interface, to support
1569                  * Private VLAN switch technologies. See arp.c.
1570                  */
1571                 if (out_dev == in_dev &&
1572                     IN_DEV_PROXY_ARP_PVLAN(in_dev) == 0) {
1573                         err = -EINVAL;
1574                         goto cleanup;
1575                 }
1576         }
1577
1578         fnhe = find_exception(&FIB_RES_NH(*res), daddr);
1579         if (do_cache) {
1580                 if (fnhe != NULL)
1581                         rth = rcu_dereference(fnhe->fnhe_rth_input);
1582                 else
1583                         rth = rcu_dereference(FIB_RES_NH(*res).nh_rth_input);
1584
1585                 if (rt_cache_valid(rth)) {
1586                         skb_dst_set_noref(skb, &rth->dst);
1587                         goto out;
1588                 }
1589         }
1590
1591         rth = rt_dst_alloc(out_dev->dev,
1592                            IN_DEV_CONF_GET(in_dev, NOPOLICY),
1593                            IN_DEV_CONF_GET(out_dev, NOXFRM), do_cache);
1594         if (!rth) {
1595                 err = -ENOBUFS;
1596                 goto cleanup;
1597         }
1598
1599         rth->rt_genid = rt_genid_ipv4(dev_net(rth->dst.dev));
1600         rth->rt_flags = flags;
1601         rth->rt_type = res->type;
1602         rth->rt_is_input = 1;
1603         rth->rt_iif     = 0;
1604         rth->rt_pmtu    = 0;
1605         rth->rt_gateway = 0;
1606         rth->rt_uses_gateway = 0;
1607         INIT_LIST_HEAD(&rth->rt_uncached);
1608         RT_CACHE_STAT_INC(in_slow_tot);
1609
1610         rth->dst.input = ip_forward;
1611         rth->dst.output = ip_output;
1612
1613         rt_set_nexthop(rth, daddr, res, fnhe, res->fi, res->type, itag);
1614         skb_dst_set(skb, &rth->dst);
1615 out:
1616         err = 0;
1617  cleanup:
1618         return err;
1619 }
1620
1621 static int ip_mkroute_input(struct sk_buff *skb,
1622                             struct fib_result *res,
1623                             const struct flowi4 *fl4,
1624                             struct in_device *in_dev,
1625                             __be32 daddr, __be32 saddr, u32 tos)
1626 {
1627 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1628         if (res->fi && res->fi->fib_nhs > 1)
1629                 fib_select_multipath(res);
1630 #endif
1631
1632         /* create a routing cache entry */
1633         return __mkroute_input(skb, res, in_dev, daddr, saddr, tos);
1634 }
1635
1636 /*
1637  *      NOTE. We drop all the packets that has local source
1638  *      addresses, because every properly looped back packet
1639  *      must have correct destination already attached by output routine.
1640  *
1641  *      Such approach solves two big problems:
1642  *      1. Not simplex devices are handled properly.
1643  *      2. IP spoofing attempts are filtered with 100% of guarantee.
1644  *      called with rcu_read_lock()
1645  */
1646
1647 static int ip_route_input_slow(struct sk_buff *skb, __be32 daddr, __be32 saddr,
1648                                u8 tos, struct net_device *dev)
1649 {
1650         struct fib_result res;
1651         struct in_device *in_dev = __in_dev_get_rcu(dev);
1652         struct flowi4   fl4;
1653         unsigned int    flags = 0;
1654         u32             itag = 0;
1655         struct rtable   *rth;
1656         int             err = -EINVAL;
1657         struct net    *net = dev_net(dev);
1658         bool do_cache;
1659
1660         /* IP on this device is disabled. */
1661
1662         if (!in_dev)
1663                 goto out;
1664
1665         /* Check for the most weird martians, which can be not detected
1666            by fib_lookup.
1667          */
1668
1669         if (ipv4_is_multicast(saddr) || ipv4_is_lbcast(saddr))
1670                 goto martian_source;
1671
1672         res.fi = NULL;
1673         if (ipv4_is_lbcast(daddr) || (saddr == 0 && daddr == 0))
1674                 goto brd_input;
1675
1676         /* Accept zero addresses only to limited broadcast;
1677          * I even do not know to fix it or not. Waiting for complains :-)
1678          */
1679         if (ipv4_is_zeronet(saddr))
1680                 goto martian_source;
1681
1682         if (ipv4_is_zeronet(daddr))
1683                 goto martian_destination;
1684
1685         /* Following code try to avoid calling IN_DEV_NET_ROUTE_LOCALNET(),
1686          * and call it once if daddr or/and saddr are loopback addresses
1687          */
1688         if (ipv4_is_loopback(daddr)) {
1689                 if (!IN_DEV_NET_ROUTE_LOCALNET(in_dev, net))
1690                         goto martian_destination;
1691         } else if (ipv4_is_loopback(saddr)) {
1692                 if (!IN_DEV_NET_ROUTE_LOCALNET(in_dev, net))
1693                         goto martian_source;
1694         }
1695
1696         /*
1697          *      Now we are ready to route packet.
1698          */
1699         fl4.flowi4_oif = 0;
1700         fl4.flowi4_iif = dev->ifindex;
1701         fl4.flowi4_mark = skb->mark;
1702         fl4.flowi4_tos = tos;
1703         fl4.flowi4_scope = RT_SCOPE_UNIVERSE;
1704         fl4.daddr = daddr;
1705         fl4.saddr = saddr;
1706         err = fib_lookup(net, &fl4, &res);
1707         if (err != 0) {
1708                 if (!IN_DEV_FORWARD(in_dev))
1709                         err = -EHOSTUNREACH;
1710                 goto no_route;
1711         }
1712
1713         if (res.type == RTN_BROADCAST)
1714                 goto brd_input;
1715
1716         if (res.type == RTN_LOCAL) {
1717                 err = fib_validate_source(skb, saddr, daddr, tos,
1718                                           0, dev, in_dev, &itag);
1719                 if (err < 0)
1720                         goto martian_source_keep_err;
1721                 goto local_input;
1722         }
1723
1724         if (!IN_DEV_FORWARD(in_dev)) {
1725                 err = -EHOSTUNREACH;
1726                 goto no_route;
1727         }
1728         if (res.type != RTN_UNICAST)
1729                 goto martian_destination;
1730
1731         err = ip_mkroute_input(skb, &res, &fl4, in_dev, daddr, saddr, tos);
1732 out:    return err;
1733
1734 brd_input:
1735         if (skb->protocol != htons(ETH_P_IP))
1736                 goto e_inval;
1737
1738         if (!ipv4_is_zeronet(saddr)) {
1739                 err = fib_validate_source(skb, saddr, 0, tos, 0, dev,
1740                                           in_dev, &itag);
1741                 if (err < 0)
1742                         goto martian_source_keep_err;
1743         }
1744         flags |= RTCF_BROADCAST;
1745         res.type = RTN_BROADCAST;
1746         RT_CACHE_STAT_INC(in_brd);
1747
1748 local_input:
1749         do_cache = false;
1750         if (res.fi) {
1751                 if (!itag) {
1752                         rth = rcu_dereference(FIB_RES_NH(res).nh_rth_input);
1753                         if (rt_cache_valid(rth)) {
1754                                 skb_dst_set_noref(skb, &rth->dst);
1755                                 err = 0;
1756                                 goto out;
1757                         }
1758                         do_cache = true;
1759                 }
1760         }
1761
1762         rth = rt_dst_alloc(net->loopback_dev,
1763                            IN_DEV_CONF_GET(in_dev, NOPOLICY), false, do_cache);
1764         if (!rth)
1765                 goto e_nobufs;
1766
1767         rth->dst.input= ip_local_deliver;
1768         rth->dst.output= ip_rt_bug;
1769 #ifdef CONFIG_IP_ROUTE_CLASSID
1770         rth->dst.tclassid = itag;
1771 #endif
1772
1773         rth->rt_genid = rt_genid_ipv4(net);
1774         rth->rt_flags   = flags|RTCF_LOCAL;
1775         rth->rt_type    = res.type;
1776         rth->rt_is_input = 1;
1777         rth->rt_iif     = 0;
1778         rth->rt_pmtu    = 0;
1779         rth->rt_gateway = 0;
1780         rth->rt_uses_gateway = 0;
1781         INIT_LIST_HEAD(&rth->rt_uncached);
1782         RT_CACHE_STAT_INC(in_slow_tot);
1783         if (res.type == RTN_UNREACHABLE) {
1784                 rth->dst.input= ip_error;
1785                 rth->dst.error= -err;
1786                 rth->rt_flags   &= ~RTCF_LOCAL;
1787         }
1788         if (do_cache) {
1789                 if (unlikely(!rt_cache_route(&FIB_RES_NH(res), rth))) {
1790                         rth->dst.flags |= DST_NOCACHE;
1791                         rt_add_uncached_list(rth);
1792                 }
1793         }
1794         skb_dst_set(skb, &rth->dst);
1795         err = 0;
1796         goto out;
1797
1798 no_route:
1799         RT_CACHE_STAT_INC(in_no_route);
1800         res.type = RTN_UNREACHABLE;
1801         if (err == -ESRCH)
1802                 err = -ENETUNREACH;
1803         goto local_input;
1804
1805         /*
1806          *      Do not cache martian addresses: they should be logged (RFC1812)
1807          */
1808 martian_destination:
1809         RT_CACHE_STAT_INC(in_martian_dst);
1810 #ifdef CONFIG_IP_ROUTE_VERBOSE
1811         if (IN_DEV_LOG_MARTIANS(in_dev))
1812                 net_warn_ratelimited("martian destination %pI4 from %pI4, dev %s\n",
1813                                      &daddr, &saddr, dev->name);
1814 #endif
1815
1816 e_inval:
1817         err = -EINVAL;
1818         goto out;
1819
1820 e_nobufs:
1821         err = -ENOBUFS;
1822         goto out;
1823
1824 martian_source:
1825         err = -EINVAL;
1826 martian_source_keep_err:
1827         ip_handle_martian_source(dev, in_dev, skb, daddr, saddr);
1828         goto out;
1829 }
1830
1831 int ip_route_input_noref(struct sk_buff *skb, __be32 daddr, __be32 saddr,
1832                          u8 tos, struct net_device *dev)
1833 {
1834         int res;
1835
1836         rcu_read_lock();
1837
1838         /* Multicast recognition logic is moved from route cache to here.
1839            The problem was that too many Ethernet cards have broken/missing
1840            hardware multicast filters :-( As result the host on multicasting
1841            network acquires a lot of useless route cache entries, sort of
1842            SDR messages from all the world. Now we try to get rid of them.
1843            Really, provided software IP multicast filter is organized
1844            reasonably (at least, hashed), it does not result in a slowdown
1845            comparing with route cache reject entries.
1846            Note, that multicast routers are not affected, because
1847            route cache entry is created eventually.
1848          */
1849         if (ipv4_is_multicast(daddr)) {
1850                 struct in_device *in_dev = __in_dev_get_rcu(dev);
1851
1852                 if (in_dev) {
1853                         int our = ip_check_mc_rcu(in_dev, daddr, saddr,
1854                                                   ip_hdr(skb)->protocol);
1855                         if (our
1856 #ifdef CONFIG_IP_MROUTE
1857                                 ||
1858                             (!ipv4_is_local_multicast(daddr) &&
1859                              IN_DEV_MFORWARD(in_dev))
1860 #endif
1861                            ) {
1862                                 int res = ip_route_input_mc(skb, daddr, saddr,
1863                                                             tos, dev, our);
1864                                 rcu_read_unlock();
1865                                 return res;
1866                         }
1867                 }
1868                 rcu_read_unlock();
1869                 return -EINVAL;
1870         }
1871         res = ip_route_input_slow(skb, daddr, saddr, tos, dev);
1872         rcu_read_unlock();
1873         return res;
1874 }
1875 EXPORT_SYMBOL(ip_route_input_noref);
1876
1877 /* called with rcu_read_lock() */
1878 static struct rtable *__mkroute_output(const struct fib_result *res,
1879                                        const struct flowi4 *fl4, int orig_oif,
1880                                        struct net_device *dev_out,
1881                                        unsigned int flags)
1882 {
1883         struct fib_info *fi = res->fi;
1884         struct fib_nh_exception *fnhe;
1885         struct in_device *in_dev;
1886         u16 type = res->type;
1887         struct rtable *rth;
1888         bool do_cache;
1889
1890         in_dev = __in_dev_get_rcu(dev_out);
1891         if (!in_dev)
1892                 return ERR_PTR(-EINVAL);
1893
1894         if (likely(!IN_DEV_ROUTE_LOCALNET(in_dev)))
1895                 if (ipv4_is_loopback(fl4->saddr) && !(dev_out->flags & IFF_LOOPBACK))
1896                         return ERR_PTR(-EINVAL);
1897
1898         if (ipv4_is_lbcast(fl4->daddr))
1899                 type = RTN_BROADCAST;
1900         else if (ipv4_is_multicast(fl4->daddr))
1901                 type = RTN_MULTICAST;
1902         else if (ipv4_is_zeronet(fl4->daddr))
1903                 return ERR_PTR(-EINVAL);
1904
1905         if (dev_out->flags & IFF_LOOPBACK)
1906                 flags |= RTCF_LOCAL;
1907
1908         do_cache = true;
1909         if (type == RTN_BROADCAST) {
1910                 flags |= RTCF_BROADCAST | RTCF_LOCAL;
1911                 fi = NULL;
1912         } else if (type == RTN_MULTICAST) {
1913                 flags |= RTCF_MULTICAST | RTCF_LOCAL;
1914                 if (!ip_check_mc_rcu(in_dev, fl4->daddr, fl4->saddr,
1915                                      fl4->flowi4_proto))
1916                         flags &= ~RTCF_LOCAL;
1917                 else
1918                         do_cache = false;
1919                 /* If multicast route do not exist use
1920                  * default one, but do not gateway in this case.
1921                  * Yes, it is hack.
1922                  */
1923                 if (fi && res->prefixlen < 4)
1924                         fi = NULL;
1925         }
1926
1927         fnhe = NULL;
1928         do_cache &= fi != NULL;
1929         if (do_cache) {
1930                 struct rtable __rcu **prth;
1931                 struct fib_nh *nh = &FIB_RES_NH(*res);
1932
1933                 fnhe = find_exception(nh, fl4->daddr);
1934                 if (fnhe)
1935                         prth = &fnhe->fnhe_rth_output;
1936                 else {
1937                         if (unlikely(fl4->flowi4_flags &
1938                                      FLOWI_FLAG_KNOWN_NH &&
1939                                      !(nh->nh_gw &&
1940                                        nh->nh_scope == RT_SCOPE_LINK))) {
1941                                 do_cache = false;
1942                                 goto add;
1943                         }
1944                         prth = __this_cpu_ptr(nh->nh_pcpu_rth_output);
1945                 }
1946                 rth = rcu_dereference(*prth);
1947                 if (rt_cache_valid(rth)) {
1948                         dst_hold(&rth->dst);
1949                         return rth;
1950                 }
1951         }
1952
1953 add:
1954         rth = rt_dst_alloc(dev_out,
1955                            IN_DEV_CONF_GET(in_dev, NOPOLICY),
1956                            IN_DEV_CONF_GET(in_dev, NOXFRM),
1957                            do_cache);
1958         if (!rth)
1959                 return ERR_PTR(-ENOBUFS);
1960
1961         rth->dst.output = ip_output;
1962
1963         rth->rt_genid = rt_genid_ipv4(dev_net(dev_out));
1964         rth->rt_flags   = flags;
1965         rth->rt_type    = type;
1966         rth->rt_is_input = 0;
1967         rth->rt_iif     = orig_oif ? : 0;
1968         rth->rt_pmtu    = 0;
1969         rth->rt_gateway = 0;
1970         rth->rt_uses_gateway = 0;
1971         INIT_LIST_HEAD(&rth->rt_uncached);
1972
1973         RT_CACHE_STAT_INC(out_slow_tot);
1974
1975         if (flags & RTCF_LOCAL)
1976                 rth->dst.input = ip_local_deliver;
1977         if (flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
1978                 if (flags & RTCF_LOCAL &&
1979                     !(dev_out->flags & IFF_LOOPBACK)) {
1980                         rth->dst.output = ip_mc_output;
1981                         RT_CACHE_STAT_INC(out_slow_mc);
1982                 }
1983 #ifdef CONFIG_IP_MROUTE
1984                 if (type == RTN_MULTICAST) {
1985                         if (IN_DEV_MFORWARD(in_dev) &&
1986                             !ipv4_is_local_multicast(fl4->daddr)) {
1987                                 rth->dst.input = ip_mr_input;
1988                                 rth->dst.output = ip_mc_output;
1989                         }
1990                 }
1991 #endif
1992         }
1993
1994         rt_set_nexthop(rth, fl4->daddr, res, fnhe, fi, type, 0);
1995
1996         return rth;
1997 }
1998
1999 /*
2000  * Major route resolver routine.
2001  */
2002
2003 struct rtable *__ip_route_output_key(struct net *net, struct flowi4 *fl4)
2004 {
2005         struct net_device *dev_out = NULL;
2006         __u8 tos = RT_FL_TOS(fl4);
2007         unsigned int flags = 0;
2008         struct fib_result res;
2009         struct rtable *rth;
2010         int orig_oif;
2011
2012         res.tclassid    = 0;
2013         res.fi          = NULL;
2014         res.table       = NULL;
2015
2016         orig_oif = fl4->flowi4_oif;
2017
2018         fl4->flowi4_iif = LOOPBACK_IFINDEX;
2019         fl4->flowi4_tos = tos & IPTOS_RT_MASK;
2020         fl4->flowi4_scope = ((tos & RTO_ONLINK) ?
2021                          RT_SCOPE_LINK : RT_SCOPE_UNIVERSE);
2022
2023         rcu_read_lock();
2024         if (fl4->saddr) {
2025                 rth = ERR_PTR(-EINVAL);
2026                 if (ipv4_is_multicast(fl4->saddr) ||
2027                     ipv4_is_lbcast(fl4->saddr) ||
2028                     ipv4_is_zeronet(fl4->saddr))
2029                         goto out;
2030
2031                 /* I removed check for oif == dev_out->oif here.
2032                    It was wrong for two reasons:
2033                    1. ip_dev_find(net, saddr) can return wrong iface, if saddr
2034                       is assigned to multiple interfaces.
2035                    2. Moreover, we are allowed to send packets with saddr
2036                       of another iface. --ANK
2037                  */
2038
2039                 if (fl4->flowi4_oif == 0 &&
2040                     (ipv4_is_multicast(fl4->daddr) ||
2041                      ipv4_is_lbcast(fl4->daddr))) {
2042                         /* It is equivalent to inet_addr_type(saddr) == RTN_LOCAL */
2043                         dev_out = __ip_dev_find(net, fl4->saddr, false);
2044                         if (dev_out == NULL)
2045                                 goto out;
2046
2047                         /* Special hack: user can direct multicasts
2048                            and limited broadcast via necessary interface
2049                            without fiddling with IP_MULTICAST_IF or IP_PKTINFO.
2050                            This hack is not just for fun, it allows
2051                            vic,vat and friends to work.
2052                            They bind socket to loopback, set ttl to zero
2053                            and expect that it will work.
2054                            From the viewpoint of routing cache they are broken,
2055                            because we are not allowed to build multicast path
2056                            with loopback source addr (look, routing cache
2057                            cannot know, that ttl is zero, so that packet
2058                            will not leave this host and route is valid).
2059                            Luckily, this hack is good workaround.
2060                          */
2061
2062                         fl4->flowi4_oif = dev_out->ifindex;
2063                         goto make_route;
2064                 }
2065
2066                 if (!(fl4->flowi4_flags & FLOWI_FLAG_ANYSRC)) {
2067                         /* It is equivalent to inet_addr_type(saddr) == RTN_LOCAL */
2068                         if (!__ip_dev_find(net, fl4->saddr, false))
2069                                 goto out;
2070                 }
2071         }
2072
2073
2074         if (fl4->flowi4_oif) {
2075                 dev_out = dev_get_by_index_rcu(net, fl4->flowi4_oif);
2076                 rth = ERR_PTR(-ENODEV);
2077                 if (dev_out == NULL)
2078                         goto out;
2079
2080                 /* RACE: Check return value of inet_select_addr instead. */
2081                 if (!(dev_out->flags & IFF_UP) || !__in_dev_get_rcu(dev_out)) {
2082                         rth = ERR_PTR(-ENETUNREACH);
2083                         goto out;
2084                 }
2085                 if (ipv4_is_local_multicast(fl4->daddr) ||
2086                     ipv4_is_lbcast(fl4->daddr)) {
2087                         if (!fl4->saddr)
2088                                 fl4->saddr = inet_select_addr(dev_out, 0,
2089                                                               RT_SCOPE_LINK);
2090                         goto make_route;
2091                 }
2092                 if (!fl4->saddr) {
2093                         if (ipv4_is_multicast(fl4->daddr))
2094                                 fl4->saddr = inet_select_addr(dev_out, 0,
2095                                                               fl4->flowi4_scope);
2096                         else if (!fl4->daddr)
2097                                 fl4->saddr = inet_select_addr(dev_out, 0,
2098                                                               RT_SCOPE_HOST);
2099                 }
2100         }
2101
2102         if (!fl4->daddr) {
2103                 fl4->daddr = fl4->saddr;
2104                 if (!fl4->daddr)
2105                         fl4->daddr = fl4->saddr = htonl(INADDR_LOOPBACK);
2106                 dev_out = net->loopback_dev;
2107                 fl4->flowi4_oif = LOOPBACK_IFINDEX;
2108                 res.type = RTN_LOCAL;
2109                 flags |= RTCF_LOCAL;
2110                 goto make_route;
2111         }
2112
2113         if (fib_lookup(net, fl4, &res)) {
2114                 res.fi = NULL;
2115                 res.table = NULL;
2116                 if (fl4->flowi4_oif) {
2117                         /* Apparently, routing tables are wrong. Assume,
2118                            that the destination is on link.
2119
2120                            WHY? DW.
2121                            Because we are allowed to send to iface
2122                            even if it has NO routes and NO assigned
2123                            addresses. When oif is specified, routing
2124                            tables are looked up with only one purpose:
2125                            to catch if destination is gatewayed, rather than
2126                            direct. Moreover, if MSG_DONTROUTE is set,
2127                            we send packet, ignoring both routing tables
2128                            and ifaddr state. --ANK
2129
2130
2131                            We could make it even if oif is unknown,
2132                            likely IPv6, but we do not.
2133                          */
2134
2135                         if (fl4->saddr == 0)
2136                                 fl4->saddr = inet_select_addr(dev_out, 0,
2137                                                               RT_SCOPE_LINK);
2138                         res.type = RTN_UNICAST;
2139                         goto make_route;
2140                 }
2141                 rth = ERR_PTR(-ENETUNREACH);
2142                 goto out;
2143         }
2144
2145         if (res.type == RTN_LOCAL) {
2146                 if (!fl4->saddr) {
2147                         if (res.fi->fib_prefsrc)
2148                                 fl4->saddr = res.fi->fib_prefsrc;
2149                         else
2150                                 fl4->saddr = fl4->daddr;
2151                 }
2152                 dev_out = net->loopback_dev;
2153                 fl4->flowi4_oif = dev_out->ifindex;
2154                 flags |= RTCF_LOCAL;
2155                 goto make_route;
2156         }
2157
2158 #ifdef CONFIG_IP_ROUTE_MULTIPATH
2159         if (res.fi->fib_nhs > 1 && fl4->flowi4_oif == 0)
2160                 fib_select_multipath(&res);
2161         else
2162 #endif
2163         if (!res.prefixlen &&
2164             res.table->tb_num_default > 1 &&
2165             res.type == RTN_UNICAST && !fl4->flowi4_oif)
2166                 fib_select_default(&res);
2167
2168         if (!fl4->saddr)
2169                 fl4->saddr = FIB_RES_PREFSRC(net, res);
2170
2171         dev_out = FIB_RES_DEV(res);
2172         fl4->flowi4_oif = dev_out->ifindex;
2173
2174
2175 make_route:
2176         rth = __mkroute_output(&res, fl4, orig_oif, dev_out, flags);
2177
2178 out:
2179         rcu_read_unlock();
2180         return rth;
2181 }
2182 EXPORT_SYMBOL_GPL(__ip_route_output_key);
2183
2184 static struct dst_entry *ipv4_blackhole_dst_check(struct dst_entry *dst, u32 cookie)
2185 {
2186         return NULL;
2187 }
2188
2189 static unsigned int ipv4_blackhole_mtu(const struct dst_entry *dst)
2190 {
2191         unsigned int mtu = dst_metric_raw(dst, RTAX_MTU);
2192
2193         return mtu ? : dst->dev->mtu;
2194 }
2195
2196 static void ipv4_rt_blackhole_update_pmtu(struct dst_entry *dst, struct sock *sk,
2197                                           struct sk_buff *skb, u32 mtu)
2198 {
2199 }
2200
2201 static void ipv4_rt_blackhole_redirect(struct dst_entry *dst, struct sock *sk,
2202                                        struct sk_buff *skb)
2203 {
2204 }
2205
2206 static u32 *ipv4_rt_blackhole_cow_metrics(struct dst_entry *dst,
2207                                           unsigned long old)
2208 {
2209         return NULL;
2210 }
2211
2212 static struct dst_ops ipv4_dst_blackhole_ops = {
2213         .family                 =       AF_INET,
2214         .protocol               =       cpu_to_be16(ETH_P_IP),
2215         .check                  =       ipv4_blackhole_dst_check,
2216         .mtu                    =       ipv4_blackhole_mtu,
2217         .default_advmss         =       ipv4_default_advmss,
2218         .update_pmtu            =       ipv4_rt_blackhole_update_pmtu,
2219         .redirect               =       ipv4_rt_blackhole_redirect,
2220         .cow_metrics            =       ipv4_rt_blackhole_cow_metrics,
2221         .neigh_lookup           =       ipv4_neigh_lookup,
2222 };
2223
2224 struct dst_entry *ipv4_blackhole_route(struct net *net, struct dst_entry *dst_orig)
2225 {
2226         struct rtable *ort = (struct rtable *) dst_orig;
2227         struct rtable *rt;
2228
2229         rt = dst_alloc(&ipv4_dst_blackhole_ops, NULL, 1, DST_OBSOLETE_NONE, 0);
2230         if (rt) {
2231                 struct dst_entry *new = &rt->dst;
2232
2233                 new->__use = 1;
2234                 new->input = dst_discard;
2235                 new->output = dst_discard_sk;
2236
2237                 new->dev = ort->dst.dev;
2238                 if (new->dev)
2239                         dev_hold(new->dev);
2240
2241                 rt->rt_is_input = ort->rt_is_input;
2242                 rt->rt_iif = ort->rt_iif;
2243                 rt->rt_pmtu = ort->rt_pmtu;
2244
2245                 rt->rt_genid = rt_genid_ipv4(net);
2246                 rt->rt_flags = ort->rt_flags;
2247                 rt->rt_type = ort->rt_type;
2248                 rt->rt_gateway = ort->rt_gateway;
2249                 rt->rt_uses_gateway = ort->rt_uses_gateway;
2250
2251                 INIT_LIST_HEAD(&rt->rt_uncached);
2252
2253                 dst_free(new);
2254         }
2255
2256         dst_release(dst_orig);
2257
2258         return rt ? &rt->dst : ERR_PTR(-ENOMEM);
2259 }
2260
2261 struct rtable *ip_route_output_flow(struct net *net, struct flowi4 *flp4,
2262                                     struct sock *sk)
2263 {
2264         struct rtable *rt = __ip_route_output_key(net, flp4);
2265
2266         if (IS_ERR(rt))
2267                 return rt;
2268
2269         if (flp4->flowi4_proto)
2270                 rt = (struct rtable *) xfrm_lookup(net, &rt->dst,
2271                                                    flowi4_to_flowi(flp4),
2272                                                    sk, 0);
2273
2274         return rt;
2275 }
2276 EXPORT_SYMBOL_GPL(ip_route_output_flow);
2277
2278 static int rt_fill_info(struct net *net,  __be32 dst, __be32 src,
2279                         struct flowi4 *fl4, struct sk_buff *skb, u32 portid,
2280                         u32 seq, int event, int nowait, unsigned int flags)
2281 {
2282         struct rtable *rt = skb_rtable(skb);
2283         struct rtmsg *r;
2284         struct nlmsghdr *nlh;
2285         unsigned long expires = 0;
2286         u32 error;
2287         u32 metrics[RTAX_MAX];
2288
2289         nlh = nlmsg_put(skb, portid, seq, event, sizeof(*r), flags);
2290         if (nlh == NULL)
2291                 return -EMSGSIZE;
2292
2293         r = nlmsg_data(nlh);
2294         r->rtm_family    = AF_INET;
2295         r->rtm_dst_len  = 32;
2296         r->rtm_src_len  = 0;
2297         r->rtm_tos      = fl4->flowi4_tos;
2298         r->rtm_table    = RT_TABLE_MAIN;
2299         if (nla_put_u32(skb, RTA_TABLE, RT_TABLE_MAIN))
2300                 goto nla_put_failure;
2301         r->rtm_type     = rt->rt_type;
2302         r->rtm_scope    = RT_SCOPE_UNIVERSE;
2303         r->rtm_protocol = RTPROT_UNSPEC;
2304         r->rtm_flags    = (rt->rt_flags & ~0xFFFF) | RTM_F_CLONED;
2305         if (rt->rt_flags & RTCF_NOTIFY)
2306                 r->rtm_flags |= RTM_F_NOTIFY;
2307
2308         if (nla_put_be32(skb, RTA_DST, dst))
2309                 goto nla_put_failure;
2310         if (src) {
2311                 r->rtm_src_len = 32;
2312                 if (nla_put_be32(skb, RTA_SRC, src))
2313                         goto nla_put_failure;
2314         }
2315         if (rt->dst.dev &&
2316             nla_put_u32(skb, RTA_OIF, rt->dst.dev->ifindex))
2317                 goto nla_put_failure;
2318 #ifdef CONFIG_IP_ROUTE_CLASSID
2319         if (rt->dst.tclassid &&
2320             nla_put_u32(skb, RTA_FLOW, rt->dst.tclassid))
2321                 goto nla_put_failure;
2322 #endif
2323         if (!rt_is_input_route(rt) &&
2324             fl4->saddr != src) {
2325                 if (nla_put_be32(skb, RTA_PREFSRC, fl4->saddr))
2326                         goto nla_put_failure;
2327         }
2328         if (rt->rt_uses_gateway &&
2329             nla_put_be32(skb, RTA_GATEWAY, rt->rt_gateway))
2330                 goto nla_put_failure;
2331
2332         expires = rt->dst.expires;
2333         if (expires) {
2334                 unsigned long now = jiffies;
2335
2336                 if (time_before(now, expires))
2337                         expires -= now;
2338                 else
2339                         expires = 0;
2340         }
2341
2342         memcpy(metrics, dst_metrics_ptr(&rt->dst), sizeof(metrics));
2343         if (rt->rt_pmtu && expires)
2344                 metrics[RTAX_MTU - 1] = rt->rt_pmtu;
2345         if (rtnetlink_put_metrics(skb, metrics) < 0)
2346                 goto nla_put_failure;
2347
2348         if (fl4->flowi4_mark &&
2349             nla_put_u32(skb, RTA_MARK, fl4->flowi4_mark))
2350                 goto nla_put_failure;
2351
2352         error = rt->dst.error;
2353
2354         if (rt_is_input_route(rt)) {
2355 #ifdef CONFIG_IP_MROUTE
2356                 if (ipv4_is_multicast(dst) && !ipv4_is_local_multicast(dst) &&
2357                     IPV4_DEVCONF_ALL(net, MC_FORWARDING)) {
2358                         int err = ipmr_get_route(net, skb,
2359                                                  fl4->saddr, fl4->daddr,
2360                                                  r, nowait);
2361                         if (err <= 0) {
2362                                 if (!nowait) {
2363                                         if (err == 0)
2364                                                 return 0;
2365                                         goto nla_put_failure;
2366                                 } else {
2367                                         if (err == -EMSGSIZE)
2368                                                 goto nla_put_failure;
2369                                         error = err;
2370                                 }
2371                         }
2372                 } else
2373 #endif
2374                         if (nla_put_u32(skb, RTA_IIF, skb->dev->ifindex))
2375                                 goto nla_put_failure;
2376         }
2377
2378         if (rtnl_put_cacheinfo(skb, &rt->dst, 0, expires, error) < 0)
2379                 goto nla_put_failure;
2380
2381         return nlmsg_end(skb, nlh);
2382
2383 nla_put_failure:
2384         nlmsg_cancel(skb, nlh);
2385         return -EMSGSIZE;
2386 }
2387
2388 static int inet_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh)
2389 {
2390         struct net *net = sock_net(in_skb->sk);
2391         struct rtmsg *rtm;
2392         struct nlattr *tb[RTA_MAX+1];
2393         struct rtable *rt = NULL;
2394         struct flowi4 fl4;
2395         __be32 dst = 0;
2396         __be32 src = 0;
2397         u32 iif;
2398         int err;
2399         int mark;
2400         struct sk_buff *skb;
2401
2402         err = nlmsg_parse(nlh, sizeof(*rtm), tb, RTA_MAX, rtm_ipv4_policy);
2403         if (err < 0)
2404                 goto errout;
2405
2406         rtm = nlmsg_data(nlh);
2407
2408         skb = alloc_skb(NLMSG_GOODSIZE, GFP_KERNEL);
2409         if (skb == NULL) {
2410                 err = -ENOBUFS;
2411                 goto errout;
2412         }
2413
2414         /* Reserve room for dummy headers, this skb can pass
2415            through good chunk of routing engine.
2416          */
2417         skb_reset_mac_header(skb);
2418         skb_reset_network_header(skb);
2419
2420         /* Bugfix: need to give ip_route_input enough of an IP header to not gag. */
2421         ip_hdr(skb)->protocol = IPPROTO_ICMP;
2422         skb_reserve(skb, MAX_HEADER + sizeof(struct iphdr));
2423
2424         src = tb[RTA_SRC] ? nla_get_be32(tb[RTA_SRC]) : 0;
2425         dst = tb[RTA_DST] ? nla_get_be32(tb[RTA_DST]) : 0;
2426         iif = tb[RTA_IIF] ? nla_get_u32(tb[RTA_IIF]) : 0;
2427         mark = tb[RTA_MARK] ? nla_get_u32(tb[RTA_MARK]) : 0;
2428
2429         memset(&fl4, 0, sizeof(fl4));
2430         fl4.daddr = dst;
2431         fl4.saddr = src;
2432         fl4.flowi4_tos = rtm->rtm_tos;
2433         fl4.flowi4_oif = tb[RTA_OIF] ? nla_get_u32(tb[RTA_OIF]) : 0;
2434         fl4.flowi4_mark = mark;
2435
2436         if (iif) {
2437                 struct net_device *dev;
2438
2439                 dev = __dev_get_by_index(net, iif);
2440                 if (dev == NULL) {
2441                         err = -ENODEV;
2442                         goto errout_free;
2443                 }
2444
2445                 skb->protocol   = htons(ETH_P_IP);
2446                 skb->dev        = dev;
2447                 skb->mark       = mark;
2448                 local_bh_disable();
2449                 err = ip_route_input(skb, dst, src, rtm->rtm_tos, dev);
2450                 local_bh_enable();
2451
2452                 rt = skb_rtable(skb);
2453                 if (err == 0 && rt->dst.error)
2454                         err = -rt->dst.error;
2455         } else {
2456                 rt = ip_route_output_key(net, &fl4);
2457
2458                 err = 0;
2459                 if (IS_ERR(rt))
2460                         err = PTR_ERR(rt);
2461         }
2462
2463         if (err)
2464                 goto errout_free;
2465
2466         skb_dst_set(skb, &rt->dst);
2467         if (rtm->rtm_flags & RTM_F_NOTIFY)
2468                 rt->rt_flags |= RTCF_NOTIFY;
2469
2470         err = rt_fill_info(net, dst, src, &fl4, skb,
2471                            NETLINK_CB(in_skb).portid, nlh->nlmsg_seq,
2472                            RTM_NEWROUTE, 0, 0);
2473         if (err <= 0)
2474                 goto errout_free;
2475
2476         err = rtnl_unicast(skb, net, NETLINK_CB(in_skb).portid);
2477 errout:
2478         return err;
2479
2480 errout_free:
2481         kfree_skb(skb);
2482         goto errout;
2483 }
2484
2485 void ip_rt_multicast_event(struct in_device *in_dev)
2486 {
2487         rt_cache_flush(dev_net(in_dev->dev));
2488 }
2489
2490 #ifdef CONFIG_SYSCTL
2491 static int ip_rt_gc_timeout __read_mostly       = RT_GC_TIMEOUT;
2492 static int ip_rt_gc_interval __read_mostly  = 60 * HZ;
2493 static int ip_rt_gc_min_interval __read_mostly  = HZ / 2;
2494 static int ip_rt_gc_elasticity __read_mostly    = 8;
2495
2496 static int ipv4_sysctl_rtcache_flush(struct ctl_table *__ctl, int write,
2497                                         void __user *buffer,
2498                                         size_t *lenp, loff_t *ppos)
2499 {
2500         struct net *net = (struct net *)__ctl->extra1;
2501
2502         if (write) {
2503                 rt_cache_flush(net);
2504                 fnhe_genid_bump(net);
2505                 return 0;
2506         }
2507
2508         return -EINVAL;
2509 }
2510
2511 static struct ctl_table ipv4_route_table[] = {
2512         {
2513                 .procname       = "gc_thresh",
2514                 .data           = &ipv4_dst_ops.gc_thresh,
2515                 .maxlen         = sizeof(int),
2516                 .mode           = 0644,
2517                 .proc_handler   = proc_dointvec,
2518         },
2519         {
2520                 .procname       = "max_size",
2521                 .data           = &ip_rt_max_size,
2522                 .maxlen         = sizeof(int),
2523                 .mode           = 0644,
2524                 .proc_handler   = proc_dointvec,
2525         },
2526         {
2527                 /*  Deprecated. Use gc_min_interval_ms */
2528
2529                 .procname       = "gc_min_interval",
2530                 .data           = &ip_rt_gc_min_interval,
2531                 .maxlen         = sizeof(int),
2532                 .mode           = 0644,
2533                 .proc_handler   = proc_dointvec_jiffies,
2534         },
2535         {
2536                 .procname       = "gc_min_interval_ms",
2537                 .data           = &ip_rt_gc_min_interval,
2538                 .maxlen         = sizeof(int),
2539                 .mode           = 0644,
2540                 .proc_handler   = proc_dointvec_ms_jiffies,
2541         },
2542         {
2543                 .procname       = "gc_timeout",
2544                 .data           = &ip_rt_gc_timeout,
2545                 .maxlen         = sizeof(int),
2546                 .mode           = 0644,
2547                 .proc_handler   = proc_dointvec_jiffies,
2548         },
2549         {
2550                 .procname       = "gc_interval",
2551                 .data           = &ip_rt_gc_interval,
2552                 .maxlen         = sizeof(int),
2553                 .mode           = 0644,
2554                 .proc_handler   = proc_dointvec_jiffies,
2555         },
2556         {
2557                 .procname       = "redirect_load",
2558                 .data           = &ip_rt_redirect_load,
2559                 .maxlen         = sizeof(int),
2560                 .mode           = 0644,
2561                 .proc_handler   = proc_dointvec,
2562         },
2563         {
2564                 .procname       = "redirect_number",
2565                 .data           = &ip_rt_redirect_number,
2566                 .maxlen         = sizeof(int),
2567                 .mode           = 0644,
2568                 .proc_handler   = proc_dointvec,
2569         },
2570         {
2571                 .procname       = "redirect_silence",
2572                 .data           = &ip_rt_redirect_silence,
2573                 .maxlen         = sizeof(int),
2574                 .mode           = 0644,
2575                 .proc_handler   = proc_dointvec,
2576         },
2577         {
2578                 .procname       = "error_cost",
2579                 .data           = &ip_rt_error_cost,
2580                 .maxlen         = sizeof(int),
2581                 .mode           = 0644,
2582                 .proc_handler   = proc_dointvec,
2583         },
2584         {
2585                 .procname       = "error_burst",
2586                 .data           = &ip_rt_error_burst,
2587                 .maxlen         = sizeof(int),
2588                 .mode           = 0644,
2589                 .proc_handler   = proc_dointvec,
2590         },
2591         {
2592                 .procname       = "gc_elasticity",
2593                 .data           = &ip_rt_gc_elasticity,
2594                 .maxlen         = sizeof(int),
2595                 .mode           = 0644,
2596                 .proc_handler   = proc_dointvec,
2597         },
2598         {
2599                 .procname       = "mtu_expires",
2600                 .data           = &ip_rt_mtu_expires,
2601                 .maxlen         = sizeof(int),
2602                 .mode           = 0644,
2603                 .proc_handler   = proc_dointvec_jiffies,
2604         },
2605         {
2606                 .procname       = "min_pmtu",
2607                 .data           = &ip_rt_min_pmtu,
2608                 .maxlen         = sizeof(int),
2609                 .mode           = 0644,
2610                 .proc_handler   = proc_dointvec,
2611         },
2612         {
2613                 .procname       = "min_adv_mss",
2614                 .data           = &ip_rt_min_advmss,
2615                 .maxlen         = sizeof(int),
2616                 .mode           = 0644,
2617                 .proc_handler   = proc_dointvec,
2618         },
2619         { }
2620 };
2621
2622 static struct ctl_table ipv4_route_flush_table[] = {
2623         {
2624                 .procname       = "flush",
2625                 .maxlen         = sizeof(int),
2626                 .mode           = 0200,
2627                 .proc_handler   = ipv4_sysctl_rtcache_flush,
2628         },
2629         { },
2630 };
2631
2632 static __net_init int sysctl_route_net_init(struct net *net)
2633 {
2634         struct ctl_table *tbl;
2635
2636         tbl = ipv4_route_flush_table;
2637         if (!net_eq(net, &init_net)) {
2638                 tbl = kmemdup(tbl, sizeof(ipv4_route_flush_table), GFP_KERNEL);
2639                 if (tbl == NULL)
2640                         goto err_dup;
2641
2642                 /* Don't export sysctls to unprivileged users */
2643                 if (net->user_ns != &init_user_ns)
2644                         tbl[0].procname = NULL;
2645         }
2646         tbl[0].extra1 = net;
2647
2648         net->ipv4.route_hdr = register_net_sysctl(net, "net/ipv4/route", tbl);
2649         if (net->ipv4.route_hdr == NULL)
2650                 goto err_reg;
2651         return 0;
2652
2653 err_reg:
2654         if (tbl != ipv4_route_flush_table)
2655                 kfree(tbl);
2656 err_dup:
2657         return -ENOMEM;
2658 }
2659
2660 static __net_exit void sysctl_route_net_exit(struct net *net)
2661 {
2662         struct ctl_table *tbl;
2663
2664         tbl = net->ipv4.route_hdr->ctl_table_arg;
2665         unregister_net_sysctl_table(net->ipv4.route_hdr);
2666         BUG_ON(tbl == ipv4_route_flush_table);
2667         kfree(tbl);
2668 }
2669
2670 static __net_initdata struct pernet_operations sysctl_route_ops = {
2671         .init = sysctl_route_net_init,
2672         .exit = sysctl_route_net_exit,
2673 };
2674 #endif
2675
2676 static __net_init int rt_genid_init(struct net *net)
2677 {
2678         atomic_set(&net->ipv4.rt_genid, 0);
2679         atomic_set(&net->fnhe_genid, 0);
2680         get_random_bytes(&net->ipv4.dev_addr_genid,
2681                          sizeof(net->ipv4.dev_addr_genid));
2682         return 0;
2683 }
2684
2685 static __net_initdata struct pernet_operations rt_genid_ops = {
2686         .init = rt_genid_init,
2687 };
2688
2689 static int __net_init ipv4_inetpeer_init(struct net *net)
2690 {
2691         struct inet_peer_base *bp = kmalloc(sizeof(*bp), GFP_KERNEL);
2692
2693         if (!bp)
2694                 return -ENOMEM;
2695         inet_peer_base_init(bp);
2696         net->ipv4.peers = bp;
2697         return 0;
2698 }
2699
2700 static void __net_exit ipv4_inetpeer_exit(struct net *net)
2701 {
2702         struct inet_peer_base *bp = net->ipv4.peers;
2703
2704         net->ipv4.peers = NULL;
2705         inetpeer_invalidate_tree(bp);
2706         kfree(bp);
2707 }
2708
2709 static __net_initdata struct pernet_operations ipv4_inetpeer_ops = {
2710         .init   =       ipv4_inetpeer_init,
2711         .exit   =       ipv4_inetpeer_exit,
2712 };
2713
2714 #ifdef CONFIG_IP_ROUTE_CLASSID
2715 struct ip_rt_acct __percpu *ip_rt_acct __read_mostly;
2716 #endif /* CONFIG_IP_ROUTE_CLASSID */
2717
2718 int __init ip_rt_init(void)
2719 {
2720         int rc = 0;
2721
2722         ip_idents = kmalloc(IP_IDENTS_SZ * sizeof(*ip_idents), GFP_KERNEL);
2723         if (!ip_idents)
2724                 panic("IP: failed to allocate ip_idents\n");
2725
2726         prandom_bytes(ip_idents, IP_IDENTS_SZ * sizeof(*ip_idents));
2727
2728 #ifdef CONFIG_IP_ROUTE_CLASSID
2729         ip_rt_acct = __alloc_percpu(256 * sizeof(struct ip_rt_acct), __alignof__(struct ip_rt_acct));
2730         if (!ip_rt_acct)
2731                 panic("IP: failed to allocate ip_rt_acct\n");
2732 #endif
2733
2734         ipv4_dst_ops.kmem_cachep =
2735                 kmem_cache_create("ip_dst_cache", sizeof(struct rtable), 0,
2736                                   SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
2737
2738         ipv4_dst_blackhole_ops.kmem_cachep = ipv4_dst_ops.kmem_cachep;
2739
2740         if (dst_entries_init(&ipv4_dst_ops) < 0)
2741                 panic("IP: failed to allocate ipv4_dst_ops counter\n");
2742
2743         if (dst_entries_init(&ipv4_dst_blackhole_ops) < 0)
2744                 panic("IP: failed to allocate ipv4_dst_blackhole_ops counter\n");
2745
2746         ipv4_dst_ops.gc_thresh = ~0;
2747         ip_rt_max_size = INT_MAX;
2748
2749         devinet_init();
2750         ip_fib_init();
2751
2752         if (ip_rt_proc_init())
2753                 pr_err("Unable to create route proc files\n");
2754 #ifdef CONFIG_XFRM
2755         xfrm_init();
2756         xfrm4_init();
2757 #endif
2758         rtnl_register(PF_INET, RTM_GETROUTE, inet_rtm_getroute, NULL, NULL);
2759
2760 #ifdef CONFIG_SYSCTL
2761         register_pernet_subsys(&sysctl_route_ops);
2762 #endif
2763         register_pernet_subsys(&rt_genid_ops);
2764         register_pernet_subsys(&ipv4_inetpeer_ops);
2765         return rc;
2766 }
2767
2768 #ifdef CONFIG_SYSCTL
2769 /*
2770  * We really need to sanitize the damn ipv4 init order, then all
2771  * this nonsense will go away.
2772  */
2773 void __init ip_static_sysctl_init(void)
2774 {
2775         register_net_sysctl(&init_net, "net/ipv4/route", ipv4_route_table);
2776 }
2777 #endif