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, <[email protected]>
  10  *              Alan Cox, <[email protected]>
  11  *              Linus Torvalds, <[email protected]>
  12  *              Alexey Kuznetsov, <[email protected]>
  13  *
  14  * Fixes:
  15  *              Alan Cox        :       Verify area fixes.
  16  *              Alan Cox        :       cli() protects routing changes
  17  *              Rui Oliveira    :       ICMP routing table updates
  18  *              ([email protected])      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 <linux/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/dst_metadata.h>
  95 #include <net/net_namespace.h>
  96 #include <net/protocol.h>
  97 #include <net/ip.h>
  98 #include <net/route.h>
  99 #include <net/inetpeer.h>
 100 #include <net/sock.h>
 101 #include <net/ip_fib.h>
 102 #include <net/arp.h>
 103 #include <net/tcp.h>
 104 #include <net/icmp.h>
 105 #include <net/xfrm.h>
 106 #include <net/lwtunnel.h>
 107 #include <net/netevent.h>
 108 #include <net/rtnetlink.h>
 109 #ifdef CONFIG_SYSCTL
 110 #include <linux/sysctl.h>
 111 #include <linux/kmemleak.h>
 112 #endif
 113 #include <net/secure_seq.h>
 114 #include <net/ip_tunnels.h>
 115 #include <net/l3mdev.h>
 116
 117 #define RT_FL_TOS(oldflp4) \
 118         ((oldflp4)->flowi4_tos & (IPTOS_RT_MASK | RTO_ONLINK))
 119
 120 #define RT_GC_TIMEOUT (300*HZ)
 121
 122 static int ip_rt_max_size;
 123 static int ip_rt_redirect_number __read_mostly  = 9;
 124 static int ip_rt_redirect_load __read_mostly    = HZ / 50;
 125 static int ip_rt_redirect_silence __read_mostly = ((HZ / 50) << (9 + 1));
 126 static int ip_rt_error_cost __read_mostly       = HZ;
 127 static int ip_rt_error_burst __read_mostly      = 5 * HZ;
 128 static int ip_rt_mtu_expires __read_mostly      = 10 * 60 * HZ;
 129 static int ip_rt_min_pmtu __read_mostly         = 512 + 20 + 20;
 130 static int ip_rt_min_advmss __read_mostly       = 256;
 131
 132 static int ip_rt_gc_timeout __read_mostly       = RT_GC_TIMEOUT;
 133 /*
 134  *      Interface to generic destination cache.
 135  */
 136
 137 static struct dst_entry *ipv4_dst_check(struct dst_entry *dst, u32 cookie);
 138 static unsigned int      ipv4_default_advmss(const struct dst_entry *dst);
 139 static unsigned int      ipv4_mtu(const struct dst_entry *dst);
 140 static struct dst_entry *ipv4_negative_advice(struct dst_entry *dst);
 141 static void              ipv4_link_failure(struct sk_buff *skb);
 142 static void              ip_rt_update_pmtu(struct dst_entry *dst, struct sock *sk,
 143                                            struct sk_buff *skb, u32 mtu);
 144 static void              ip_do_redirect(struct dst_entry *dst, struct sock *sk,
 145                                         struct sk_buff *skb);
 146 static void             ipv4_dst_destroy(struct dst_entry *dst);
 147
 148 static u32 *ipv4_cow_metrics(struct dst_entry *dst, unsigned long old)
 149 {
 150         WARN_ON(1);
 151         return NULL;
 152 }
 153
 154 static struct neighbour *ipv4_neigh_lookup(const struct dst_entry *dst,
 155                                            struct sk_buff *skb,
 156                                            const void *daddr);
 157 static void ipv4_confirm_neigh(const struct dst_entry *dst, const void *daddr);
 158
 159 static struct dst_ops ipv4_dst_ops = {
 160         .family =               AF_INET,
 161         .check =                ipv4_dst_check,
 162         .default_advmss =       ipv4_default_advmss,
 163         .mtu =                  ipv4_mtu,
 164         .cow_metrics =          ipv4_cow_metrics,
 165         .destroy =              ipv4_dst_destroy,
 166         .negative_advice =      ipv4_negative_advice,
 167         .link_failure =         ipv4_link_failure,
 168         .update_pmtu =          ip_rt_update_pmtu,
 169         .redirect =             ip_do_redirect,
 170         .local_out =            __ip_local_out,
 171         .neigh_lookup =         ipv4_neigh_lookup,
 172         .confirm_neigh =        ipv4_confirm_neigh,
 173 };
 174
 175 #define ECN_OR_COST(class)      TC_PRIO_##class
 176
 177 const __u8 ip_tos2prio[16] = {
 178         TC_PRIO_BESTEFFORT,
 179         ECN_OR_COST(BESTEFFORT),
 180         TC_PRIO_BESTEFFORT,
 181         ECN_OR_COST(BESTEFFORT),
 182         TC_PRIO_BULK,
 183         ECN_OR_COST(BULK),
 184         TC_PRIO_BULK,
 185         ECN_OR_COST(BULK),
 186         TC_PRIO_INTERACTIVE,
 187         ECN_OR_COST(INTERACTIVE),
 188         TC_PRIO_INTERACTIVE,
 189         ECN_OR_COST(INTERACTIVE),
 190         TC_PRIO_INTERACTIVE_BULK,
 191         ECN_OR_COST(INTERACTIVE_BULK),
 192         TC_PRIO_INTERACTIVE_BULK,
 193         ECN_OR_COST(INTERACTIVE_BULK)
 194 };
 195 EXPORT_SYMBOL(ip_tos2prio);
 196
 197 static DEFINE_PER_CPU(struct rt_cache_stat, rt_cache_stat);
 198 #define RT_CACHE_STAT_INC(field) raw_cpu_inc(rt_cache_stat.field)
 199
 200 #ifdef CONFIG_PROC_FS
 201 static void *rt_cache_seq_start(struct seq_file *seq, loff_t *pos)
 202 {
 203         if (*pos)
 204                 return NULL;
 205         return SEQ_START_TOKEN;
 206 }
 207
 208 static void *rt_cache_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 209 {
 210         ++*pos;
 211         return NULL;
 212 }
 213
 214 static void rt_cache_seq_stop(struct seq_file *seq, void *v)
 215 {
 216 }
 217
 218 static int rt_cache_seq_show(struct seq_file *seq, void *v)
 219 {
 220         if (v == SEQ_START_TOKEN)
 221                 seq_printf(seq, "%-127s\n",
 222                            "Iface\tDestination\tGateway \tFlags\t\tRefCnt\tUse\t"
 223                            "Metric\tSource\t\tMTU\tWindow\tIRTT\tTOS\tHHRef\t"
 224                            "HHUptod\tSpecDst");
 225         return 0;
 226 }
 227
 228 static const struct seq_operations rt_cache_seq_ops = {
 229         .start  = rt_cache_seq_start,
 230         .next   = rt_cache_seq_next,
 231         .stop   = rt_cache_seq_stop,
 232         .show   = rt_cache_seq_show,
 233 };
 234
 235 static int rt_cache_seq_open(struct inode *inode, struct file *file)
 236 {
 237         return seq_open(file, &rt_cache_seq_ops);
 238 }
 239
 240 static const struct file_operations rt_cache_seq_fops = {
 241         .owner   = THIS_MODULE,
 242         .open    = rt_cache_seq_open,
 243         .read    = seq_read,
 244         .llseek  = seq_lseek,
 245         .release = seq_release,
 246 };
 247
 248
 249 static void *rt_cpu_seq_start(struct seq_file *seq, loff_t *pos)
 250 {
 251         int cpu;
 252
 253         if (*pos == 0)
 254                 return SEQ_START_TOKEN;
 255
 256         for (cpu = *pos-1; cpu < nr_cpu_ids; ++cpu) {
 257                 if (!cpu_possible(cpu))
 258                         continue;
 259                 *pos = cpu+1;
 260                 return &per_cpu(rt_cache_stat, cpu);
 261         }
 262         return NULL;
 263 }
 264
 265 static void *rt_cpu_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 266 {
 267         int cpu;
 268
 269         for (cpu = *pos; cpu < nr_cpu_ids; ++cpu) {
 270                 if (!cpu_possible(cpu))
 271                         continue;
 272                 *pos = cpu+1;
 273                 return &per_cpu(rt_cache_stat, cpu);
 274         }
 275         return NULL;
 276
 277 }
 278
 279 static void rt_cpu_seq_stop(struct seq_file *seq, void *v)
 280 {
 281
 282 }
 283
 284 static int rt_cpu_seq_show(struct seq_file *seq, void *v)
 285 {
 286         struct rt_cache_stat *st = v;
 287
 288         if (v == SEQ_START_TOKEN) {
 289                 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");
 290                 return 0;
 291         }
 292
 293         seq_printf(seq,"%08x  %08x %08x %08x %08x %08x %08x %08x "
 294                    " %08x %08x %08x %08x %08x %08x %08x %08x %08x \n",
 295                    dst_entries_get_slow(&ipv4_dst_ops),
 296                    0, /* st->in_hit */
 297                    st->in_slow_tot,
 298                    st->in_slow_mc,
 299                    st->in_no_route,
 300                    st->in_brd,
 301                    st->in_martian_dst,
 302                    st->in_martian_src,
 303
 304                    0, /* st->out_hit */
 305                    st->out_slow_tot,
 306                    st->out_slow_mc,
 307
 308                    0, /* st->gc_total */
 309                    0, /* st->gc_ignored */
 310                    0, /* st->gc_goal_miss */
 311                    0, /* st->gc_dst_overflow */
 312                    0, /* st->in_hlist_search */
 313                    0  /* st->out_hlist_search */
 314                 );
 315         return 0;
 316 }
 317
 318 static const struct seq_operations rt_cpu_seq_ops = {
 319         .start  = rt_cpu_seq_start,
 320         .next   = rt_cpu_seq_next,
 321         .stop   = rt_cpu_seq_stop,
 322         .show   = rt_cpu_seq_show,
 323 };
 324
 325
 326 static int rt_cpu_seq_open(struct inode *inode, struct file *file)
 327 {
 328         return seq_open(file, &rt_cpu_seq_ops);
 329 }
 330
 331 static const struct file_operations rt_cpu_seq_fops = {
 332         .owner   = THIS_MODULE,
 333         .open    = rt_cpu_seq_open,
 334         .read    = seq_read,
 335         .llseek  = seq_lseek,
 336         .release = seq_release,
 337 };
 338
 339 #ifdef CONFIG_IP_ROUTE_CLASSID
 340 static int rt_acct_proc_show(struct seq_file *m, void *v)
 341 {
 342         struct ip_rt_acct *dst, *src;
 343         unsigned int i, j;
 344
 345         dst = kcalloc(256, sizeof(struct ip_rt_acct), GFP_KERNEL);
 346         if (!dst)
 347                 return -ENOMEM;
 348
 349         for_each_possible_cpu(i) {
 350                 src = (struct ip_rt_acct *)per_cpu_ptr(ip_rt_acct, i);
 351                 for (j = 0; j < 256; j++) {
 352                         dst[j].o_bytes   += src[j].o_bytes;
 353                         dst[j].o_packets += src[j].o_packets;
 354                         dst[j].i_bytes   += src[j].i_bytes;
 355                         dst[j].i_packets += src[j].i_packets;
 356                 }
 357         }
 358
 359         seq_write(m, dst, 256 * sizeof(struct ip_rt_acct));
 360         kfree(dst);
 361         return 0;
 362 }
 363
 364 static int rt_acct_proc_open(struct inode *inode, struct file *file)
 365 {
 366         return single_open(file, rt_acct_proc_show, NULL);
 367 }
 368
 369 static const struct file_operations rt_acct_proc_fops = {
 370         .owner          = THIS_MODULE,
 371         .open           = rt_acct_proc_open,
 372         .read           = seq_read,
 373         .llseek         = seq_lseek,
 374         .release        = single_release,
 375 };
 376 #endif
 377
 378 static int __net_init ip_rt_do_proc_init(struct net *net)
 379 {
 380         struct proc_dir_entry *pde;
 381
 382         pde = proc_create("rt_cache", S_IRUGO, net->proc_net,
 383                           &rt_cache_seq_fops);
 384         if (!pde)
 385                 goto err1;
 386
 387         pde = proc_create("rt_cache", S_IRUGO,
 388                           net->proc_net_stat, &rt_cpu_seq_fops);
 389         if (!pde)
 390                 goto err2;
 391
 392 #ifdef CONFIG_IP_ROUTE_CLASSID
 393         pde = proc_create("rt_acct", 0, net->proc_net, &rt_acct_proc_fops);
 394         if (!pde)
 395                 goto err3;
 396 #endif
 397         return 0;
 398
 399 #ifdef CONFIG_IP_ROUTE_CLASSID
 400 err3:
 401         remove_proc_entry("rt_cache", net->proc_net_stat);
 402 #endif
 403 err2:
 404         remove_proc_entry("rt_cache", net->proc_net);
 405 err1:
 406         return -ENOMEM;
 407 }
 408
 409 static void __net_exit ip_rt_do_proc_exit(struct net *net)
 410 {
 411         remove_proc_entry("rt_cache", net->proc_net_stat);
 412         remove_proc_entry("rt_cache", net->proc_net);
 413 #ifdef CONFIG_IP_ROUTE_CLASSID
 414         remove_proc_entry("rt_acct", net->proc_net);
 415 #endif
 416 }
 417
 418 static struct pernet_operations ip_rt_proc_ops __net_initdata =  {
 419         .init = ip_rt_do_proc_init,
 420         .exit = ip_rt_do_proc_exit,
 421 };
 422
 423 static int __init ip_rt_proc_init(void)
 424 {
 425         return register_pernet_subsys(&ip_rt_proc_ops);
 426 }
 427
 428 #else
 429 static inline int ip_rt_proc_init(void)
 430 {
 431         return 0;
 432 }
 433 #endif /* CONFIG_PROC_FS */
 434
 435 static inline bool rt_is_expired(const struct rtable *rth)
 436 {
 437         return rth->rt_genid != rt_genid_ipv4(dev_net(rth->dst.dev));
 438 }
 439
 440 void rt_cache_flush(struct net *net)
 441 {
 442         rt_genid_bump_ipv4(net);
 443 }
 444
 445 static struct neighbour *ipv4_neigh_lookup(const struct dst_entry *dst,
 446                                            struct sk_buff *skb,
 447                                            const void *daddr)
 448 {
 449         struct net_device *dev = dst->dev;
 450         const __be32 *pkey = daddr;
 451         const struct rtable *rt;
 452         struct neighbour *n;
 453
 454         rt = (const struct rtable *) dst;
 455         if (rt->rt_gateway)
 456                 pkey = (const __be32 *) &rt->rt_gateway;
 457         else if (skb)
 458                 pkey = &ip_hdr(skb)->daddr;
 459
 460         n = __ipv4_neigh_lookup(dev, *(__force u32 *)pkey);
 461         if (n)
 462                 return n;
 463         return neigh_create(&arp_tbl, pkey, dev);
 464 }
 465
 466 static void ipv4_confirm_neigh(const struct dst_entry *dst, const void *daddr)
 467 {
 468         struct net_device *dev = dst->dev;
 469         const __be32 *pkey = daddr;
 470         const struct rtable *rt;
 471
 472         rt = (const struct rtable *)dst;
 473         if (rt->rt_gateway)
 474                 pkey = (const __be32 *)&rt->rt_gateway;
 475         else if (!daddr ||
 476                  (rt->rt_flags &
 477                   (RTCF_MULTICAST | RTCF_BROADCAST | RTCF_LOCAL)))
 478                 return;
 479
 480         __ipv4_confirm_neigh(dev, *(__force u32 *)pkey);
 481 }
 482
 483 #define IP_IDENTS_SZ 2048u
 484
 485 static atomic_t *ip_idents __read_mostly;
 486 static u32 *ip_tstamps __read_mostly;
 487
 488 /* In order to protect privacy, we add a perturbation to identifiers
 489  * if one generator is seldom used. This makes hard for an attacker
 490  * to infer how many packets were sent between two points in time.
 491  */
 492 u32 ip_idents_reserve(u32 hash, int segs)
 493 {
 494         u32 *p_tstamp = ip_tstamps + hash % IP_IDENTS_SZ;
 495         atomic_t *p_id = ip_idents + hash % IP_IDENTS_SZ;
 496         u32 old = ACCESS_ONCE(*p_tstamp);
 497         u32 now = (u32)jiffies;
 498         u32 new, delta = 0;
 499
 500         if (old != now && cmpxchg(p_tstamp, old, now) == old)
 501                 delta = prandom_u32_max(now - old);
 502
 503         /* Do not use atomic_add_return() as it makes UBSAN unhappy */
 504         do {
 505                 old = (u32)atomic_read(p_id);
 506                 new = old + delta + segs;
 507         } while (atomic_cmpxchg(p_id, old, new) != old);
 508
 509         return new - segs;
 510 }
 511 EXPORT_SYMBOL(ip_idents_reserve);
 512
 513 void __ip_select_ident(struct net *net, struct iphdr *iph, int segs)
 514 {
 515         static u32 ip_idents_hashrnd __read_mostly;
 516         u32 hash, id;
 517
 518         net_get_random_once(&ip_idents_hashrnd, sizeof(ip_idents_hashrnd));
 519
 520         hash = jhash_3words((__force u32)iph->daddr,
 521                             (__force u32)iph->saddr,
 522                             iph->protocol ^ net_hash_mix(net),
 523                             ip_idents_hashrnd);
 524         id = ip_idents_reserve(hash, segs);
 525         iph->id = htons(id);
 526 }
 527 EXPORT_SYMBOL(__ip_select_ident);
 528
 529 static void __build_flow_key(const struct net *net, struct flowi4 *fl4,
 530                              const struct sock *sk,
 531                              const struct iphdr *iph,
 532                              int oif, u8 tos,
 533                              u8 prot, u32 mark, int flow_flags)
 534 {
 535         if (sk) {
 536                 const struct inet_sock *inet = inet_sk(sk);
 537
 538                 oif = sk->sk_bound_dev_if;
 539                 mark = sk->sk_mark;
 540                 tos = RT_CONN_FLAGS(sk);
 541                 prot = inet->hdrincl ? IPPROTO_RAW : sk->sk_protocol;
 542         }
 543         flowi4_init_output(fl4, oif, mark, tos,
 544                            RT_SCOPE_UNIVERSE, prot,
 545                            flow_flags,
 546                            iph->daddr, iph->saddr, 0, 0,
 547                            sock_net_uid(net, sk));
 548 }
 549
 550 static void build_skb_flow_key(struct flowi4 *fl4, const struct sk_buff *skb,
 551                                const struct sock *sk)
 552 {
 553         const struct net *net = dev_net(skb->dev);
 554         const struct iphdr *iph = ip_hdr(skb);
 555         int oif = skb->dev->ifindex;
 556         u8 tos = RT_TOS(iph->tos);
 557         u8 prot = iph->protocol;
 558         u32 mark = skb->mark;
 559
 560         __build_flow_key(net, fl4, sk, iph, oif, tos, prot, mark, 0);
 561 }
 562
 563 static void build_sk_flow_key(struct flowi4 *fl4, const struct sock *sk)
 564 {
 565         const struct inet_sock *inet = inet_sk(sk);
 566         const struct ip_options_rcu *inet_opt;
 567         __be32 daddr = inet->inet_daddr;
 568
 569         rcu_read_lock();
 570         inet_opt = rcu_dereference(inet->inet_opt);
 571         if (inet_opt && inet_opt->opt.srr)
 572                 daddr = inet_opt->opt.faddr;
 573         flowi4_init_output(fl4, sk->sk_bound_dev_if, sk->sk_mark,
 574                            RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE,
 575                            inet->hdrincl ? IPPROTO_RAW : sk->sk_protocol,
 576                            inet_sk_flowi_flags(sk),
 577                            daddr, inet->inet_saddr, 0, 0, sk->sk_uid);
 578         rcu_read_unlock();
 579 }
 580
 581 static void ip_rt_build_flow_key(struct flowi4 *fl4, const struct sock *sk,
 582                                  const struct sk_buff *skb)
 583 {
 584         if (skb)
 585                 build_skb_flow_key(fl4, skb, sk);
 586         else
 587                 build_sk_flow_key(fl4, sk);
 588 }
 589
 590 static inline void rt_free(struct rtable *rt)
 591 {
 592         call_rcu(&rt->dst.rcu_head, dst_rcu_free);
 593 }
 594
 595 static DEFINE_SPINLOCK(fnhe_lock);
 596
 597 static void fnhe_flush_routes(struct fib_nh_exception *fnhe)
 598 {
 599         struct rtable *rt;
 600
 601         rt = rcu_dereference(fnhe->fnhe_rth_input);
 602         if (rt) {
 603                 RCU_INIT_POINTER(fnhe->fnhe_rth_input, NULL);
 604                 rt_free(rt);
 605         }
 606         rt = rcu_dereference(fnhe->fnhe_rth_output);
 607         if (rt) {
 608                 RCU_INIT_POINTER(fnhe->fnhe_rth_output, NULL);
 609                 rt_free(rt);
 610         }
 611 }
 612
 613 static struct fib_nh_exception *fnhe_oldest(struct fnhe_hash_bucket *hash)
 614 {
 615         struct fib_nh_exception *fnhe, *oldest;
 616
 617         oldest = rcu_dereference(hash->chain);
 618         for (fnhe = rcu_dereference(oldest->fnhe_next); fnhe;
 619              fnhe = rcu_dereference(fnhe->fnhe_next)) {
 620                 if (time_before(fnhe->fnhe_stamp, oldest->fnhe_stamp))
 621                         oldest = fnhe;
 622         }
 623         fnhe_flush_routes(oldest);
 624         return oldest;
 625 }
 626
 627 static inline u32 fnhe_hashfun(__be32 daddr)
 628 {
 629         static u32 fnhe_hashrnd __read_mostly;
 630         u32 hval;
 631
 632         net_get_random_once(&fnhe_hashrnd, sizeof(fnhe_hashrnd));
 633         hval = jhash_1word((__force u32) daddr, fnhe_hashrnd);
 634         return hash_32(hval, FNHE_HASH_SHIFT);
 635 }
 636
 637 static void fill_route_from_fnhe(struct rtable *rt, struct fib_nh_exception *fnhe)
 638 {
 639         rt->rt_pmtu = fnhe->fnhe_pmtu;
 640         rt->dst.expires = fnhe->fnhe_expires;
 641
 642         if (fnhe->fnhe_gw) {
 643                 rt->rt_flags |= RTCF_REDIRECTED;
 644                 rt->rt_gateway = fnhe->fnhe_gw;
 645                 rt->rt_uses_gateway = 1;
 646         }
 647 }
 648
 649 static void update_or_create_fnhe(struct fib_nh *nh, __be32 daddr, __be32 gw,
 650                                   u32 pmtu, unsigned long expires)
 651 {
 652         struct fnhe_hash_bucket *hash;
 653         struct fib_nh_exception *fnhe;
 654         struct rtable *rt;
 655         unsigned int i;
 656         int depth;
 657         u32 hval = fnhe_hashfun(daddr);
 658
 659         spin_lock_bh(&fnhe_lock);
 660
 661         hash = rcu_dereference(nh->nh_exceptions);
 662         if (!hash) {
 663                 hash = kzalloc(FNHE_HASH_SIZE * sizeof(*hash), GFP_ATOMIC);
 664                 if (!hash)
 665                         goto out_unlock;
 666                 rcu_assign_pointer(nh->nh_exceptions, hash);
 667         }
 668
 669         hash += hval;
 670
 671         depth = 0;
 672         for (fnhe = rcu_dereference(hash->chain); fnhe;
 673              fnhe = rcu_dereference(fnhe->fnhe_next)) {
 674                 if (fnhe->fnhe_daddr == daddr)
 675                         break;
 676                 depth++;
 677         }
 678
 679         if (fnhe) {
 680                 if (gw)
 681                         fnhe->fnhe_gw = gw;
 682                 if (pmtu) {
 683                         fnhe->fnhe_pmtu = pmtu;
 684                         fnhe->fnhe_expires = max(1UL, expires);
 685                 }
 686                 /* Update all cached dsts too */
 687                 rt = rcu_dereference(fnhe->fnhe_rth_input);
 688                 if (rt)
 689                         fill_route_from_fnhe(rt, fnhe);
 690                 rt = rcu_dereference(fnhe->fnhe_rth_output);
 691                 if (rt)
 692                         fill_route_from_fnhe(rt, fnhe);
 693         } else {
 694                 if (depth > FNHE_RECLAIM_DEPTH)
 695                         fnhe = fnhe_oldest(hash);
 696                 else {
 697                         fnhe = kzalloc(sizeof(*fnhe), GFP_ATOMIC);
 698                         if (!fnhe)
 699                                 goto out_unlock;
 700
 701                         fnhe->fnhe_next = hash->chain;
 702                         rcu_assign_pointer(hash->chain, fnhe);
 703                 }
 704                 fnhe->fnhe_genid = fnhe_genid(dev_net(nh->nh_dev));
 705                 fnhe->fnhe_daddr = daddr;
 706                 fnhe->fnhe_gw = gw;
 707                 fnhe->fnhe_pmtu = pmtu;
 708                 fnhe->fnhe_expires = expires;
 709
 710                 /* Exception created; mark the cached routes for the nexthop
 711                  * stale, so anyone caching it rechecks if this exception
 712                  * applies to them.
 713                  */
 714                 rt = rcu_dereference(nh->nh_rth_input);
 715                 if (rt)
 716                         rt->dst.obsolete = DST_OBSOLETE_KILL;
 717
 718                 for_each_possible_cpu(i) {
 719                         struct rtable __rcu **prt;
 720                         prt = per_cpu_ptr(nh->nh_pcpu_rth_output, i);
 721                         rt = rcu_dereference(*prt);
 722                         if (rt)
 723                                 rt->dst.obsolete = DST_OBSOLETE_KILL;
 724                 }
 725         }
 726
 727         fnhe->fnhe_stamp = jiffies;
 728
 729 out_unlock:
 730         spin_unlock_bh(&fnhe_lock);
 731 }
 732
 733 static void __ip_do_redirect(struct rtable *rt, struct sk_buff *skb, struct flowi4 *fl4,
 734                              bool kill_route)
 735 {
 736         __be32 new_gw = icmp_hdr(skb)->un.gateway;
 737         __be32 old_gw = ip_hdr(skb)->saddr;
 738         struct net_device *dev = skb->dev;
 739         struct in_device *in_dev;
 740         struct fib_result res;
 741         struct neighbour *n;
 742         struct net *net;
 743
 744         switch (icmp_hdr(skb)->code & 7) {
 745         case ICMP_REDIR_NET:
 746         case ICMP_REDIR_NETTOS:
 747         case ICMP_REDIR_HOST:
 748         case ICMP_REDIR_HOSTTOS:
 749                 break;
 750
 751         default:
 752                 return;
 753         }
 754
 755         if (rt->rt_gateway != old_gw)
 756                 return;
 757
 758         in_dev = __in_dev_get_rcu(dev);
 759         if (!in_dev)
 760                 return;
 761
 762         net = dev_net(dev);
 763         if (new_gw == old_gw || !IN_DEV_RX_REDIRECTS(in_dev) ||
 764             ipv4_is_multicast(new_gw) || ipv4_is_lbcast(new_gw) ||
 765             ipv4_is_zeronet(new_gw))
 766                 goto reject_redirect;
 767
 768         if (!IN_DEV_SHARED_MEDIA(in_dev)) {
 769                 if (!inet_addr_onlink(in_dev, new_gw, old_gw))
 770                         goto reject_redirect;
 771                 if (IN_DEV_SEC_REDIRECTS(in_dev) && ip_fib_check_default(new_gw, dev))
 772                         goto reject_redirect;
 773         } else {
 774                 if (inet_addr_type(net, new_gw) != RTN_UNICAST)
 775                         goto reject_redirect;
 776         }
 777
 778         n = __ipv4_neigh_lookup(rt->dst.dev, new_gw);
 779         if (!n)
 780                 n = neigh_create(&arp_tbl, &new_gw, rt->dst.dev);
 781         if (!IS_ERR(n)) {
 782                 if (!(n->nud_state & NUD_VALID)) {
 783                         neigh_event_send(n, NULL);
 784                 } else {
 785                         if (fib_lookup(net, fl4, &res, 0) == 0) {
 786                                 struct fib_nh *nh = &FIB_RES_NH(res);
 787
 788                                 update_or_create_fnhe(nh, fl4->daddr, new_gw,
 789                                                 0, jiffies + ip_rt_gc_timeout);
 790                         }
 791                         if (kill_route)
 792                                 rt->dst.obsolete = DST_OBSOLETE_KILL;
 793                         call_netevent_notifiers(NETEVENT_NEIGH_UPDATE, n);
 794                 }
 795                 neigh_release(n);
 796         }
 797         return;
 798
 799 reject_redirect:
 800 #ifdef CONFIG_IP_ROUTE_VERBOSE
 801         if (IN_DEV_LOG_MARTIANS(in_dev)) {
 802                 const struct iphdr *iph = (const struct iphdr *) skb->data;
 803                 __be32 daddr = iph->daddr;
 804                 __be32 saddr = iph->saddr;
 805
 806                 net_info_ratelimited("Redirect from %pI4 on %s about %pI4 ignored\n"
 807                                      "  Advised path = %pI4 -> %pI4\n",
 808                                      &old_gw, dev->name, &new_gw,
 809                                      &saddr, &daddr);
 810         }
 811 #endif
 812         ;
 813 }
 814
 815 static void ip_do_redirect(struct dst_entry *dst, struct sock *sk, struct sk_buff *skb)
 816 {
 817         struct rtable *rt;
 818         struct flowi4 fl4;
 819         const struct iphdr *iph = (const struct iphdr *) skb->data;
 820         struct net *net = dev_net(skb->dev);
 821         int oif = skb->dev->ifindex;
 822         u8 tos = RT_TOS(iph->tos);
 823         u8 prot = iph->protocol;
 824         u32 mark = skb->mark;
 825
 826         rt = (struct rtable *) dst;
 827
 828         __build_flow_key(net, &fl4, sk, iph, oif, tos, prot, mark, 0);
 829         __ip_do_redirect(rt, skb, &fl4, true);
 830 }
 831
 832 static struct dst_entry *ipv4_negative_advice(struct dst_entry *dst)
 833 {
 834         struct rtable *rt = (struct rtable *)dst;
 835         struct dst_entry *ret = dst;
 836
 837         if (rt) {
 838                 if (dst->obsolete > 0) {
 839                         ip_rt_put(rt);
 840                         ret = NULL;
 841                 } else if ((rt->rt_flags & RTCF_REDIRECTED) ||
 842                            rt->dst.expires) {
 843                         ip_rt_put(rt);
 844                         ret = NULL;
 845                 }
 846         }
 847         return ret;
 848 }
 849
 850 /*
 851  * Algorithm:
 852  *      1. The first ip_rt_redirect_number redirects are sent
 853  *         with exponential backoff, then we stop sending them at all,
 854  *         assuming that the host ignores our redirects.
 855  *      2. If we did not see packets requiring redirects
 856  *         during ip_rt_redirect_silence, we assume that the host
 857  *         forgot redirected route and start to send redirects again.
 858  *
 859  * This algorithm is much cheaper and more intelligent than dumb load limiting
 860  * in icmp.c.
 861  *
 862  * NOTE. Do not forget to inhibit load limiting for redirects (redundant)
 863  * and "frag. need" (breaks PMTU discovery) in icmp.c.
 864  */
 865
 866 void ip_rt_send_redirect(struct sk_buff *skb)
 867 {
 868         struct rtable *rt = skb_rtable(skb);
 869         struct in_device *in_dev;
 870         struct inet_peer *peer;
 871         struct net *net;
 872         int log_martians;
 873         int vif;
 874
 875         rcu_read_lock();
 876         in_dev = __in_dev_get_rcu(rt->dst.dev);
 877         if (!in_dev || !IN_DEV_TX_REDIRECTS(in_dev)) {
 878                 rcu_read_unlock();
 879                 return;
 880         }
 881         log_martians = IN_DEV_LOG_MARTIANS(in_dev);
 882         vif = l3mdev_master_ifindex_rcu(rt->dst.dev);
 883         rcu_read_unlock();
 884
 885         net = dev_net(rt->dst.dev);
 886         peer = inet_getpeer_v4(net->ipv4.peers, ip_hdr(skb)->saddr, vif, 1);
 887         if (!peer) {
 888                 icmp_send(skb, ICMP_REDIRECT, ICMP_REDIR_HOST,
 889                           rt_nexthop(rt, ip_hdr(skb)->daddr));
 890                 return;
 891         }
 892
 893         /* No redirected packets during ip_rt_redirect_silence;
 894          * reset the algorithm.
 895          */
 896         if (time_after(jiffies, peer->rate_last + ip_rt_redirect_silence))
 897                 peer->rate_tokens = 0;
 898
 899         /* Too many ignored redirects; do not send anything
 900          * set dst.rate_last to the last seen redirected packet.
 901          */
 902         if (peer->rate_tokens >= ip_rt_redirect_number) {
 903                 peer->rate_last = jiffies;
 904                 goto out_put_peer;
 905         }
 906
 907         /* Check for load limit; set rate_last to the latest sent
 908          * redirect.
 909          */
 910         if (peer->rate_tokens == 0 ||
 911             time_after(jiffies,
 912                        (peer->rate_last +
 913                         (ip_rt_redirect_load << peer->rate_tokens)))) {
 914                 __be32 gw = rt_nexthop(rt, ip_hdr(skb)->daddr);
 915
 916                 icmp_send(skb, ICMP_REDIRECT, ICMP_REDIR_HOST, gw);
 917                 peer->rate_last = jiffies;
 918                 ++peer->rate_tokens;
 919 #ifdef CONFIG_IP_ROUTE_VERBOSE
 920                 if (log_martians &&
 921                     peer->rate_tokens == ip_rt_redirect_number)
 922                         net_warn_ratelimited("host %pI4/if%d ignores redirects for %pI4 to %pI4\n",
 923                                              &ip_hdr(skb)->saddr, inet_iif(skb),
 924                                              &ip_hdr(skb)->daddr, &gw);
 925 #endif
 926         }
 927 out_put_peer:
 928         inet_putpeer(peer);
 929 }
 930
 931 static int ip_error(struct sk_buff *skb)
 932 {
 933         struct in_device *in_dev = __in_dev_get_rcu(skb->dev);
 934         struct rtable *rt = skb_rtable(skb);
 935         struct inet_peer *peer;
 936         unsigned long now;
 937         struct net *net;
 938         bool send;
 939         int code;
 940
 941         /* IP on this device is disabled. */
 942         if (!in_dev)
 943                 goto out;
 944
 945         net = dev_net(rt->dst.dev);
 946         if (!IN_DEV_FORWARD(in_dev)) {
 947                 switch (rt->dst.error) {
 948                 case EHOSTUNREACH:
 949                         __IP_INC_STATS(net, IPSTATS_MIB_INADDRERRORS);
 950                         break;
 951
 952                 case ENETUNREACH:
 953                         __IP_INC_STATS(net, IPSTATS_MIB_INNOROUTES);
 954                         break;
 955                 }
 956                 goto out;
 957         }
 958
 959         switch (rt->dst.error) {
 960         case EINVAL:
 961         default:
 962                 goto out;
 963         case EHOSTUNREACH:
 964                 code = ICMP_HOST_UNREACH;
 965                 break;
 966         case ENETUNREACH:
 967                 code = ICMP_NET_UNREACH;
 968                 __IP_INC_STATS(net, IPSTATS_MIB_INNOROUTES);
 969                 break;
 970         case EACCES:
 971                 code = ICMP_PKT_FILTERED;
 972                 break;
 973         }
 974
 975         peer = inet_getpeer_v4(net->ipv4.peers, ip_hdr(skb)->saddr,
 976                                l3mdev_master_ifindex(skb->dev), 1);
 977
 978         send = true;
 979         if (peer) {
 980                 now = jiffies;
 981                 peer->rate_tokens += now - peer->rate_last;
 982                 if (peer->rate_tokens > ip_rt_error_burst)
 983                         peer->rate_tokens = ip_rt_error_burst;
 984                 peer->rate_last = now;
 985                 if (peer->rate_tokens >= ip_rt_error_cost)
 986                         peer->rate_tokens -= ip_rt_error_cost;
 987                 else
 988                         send = false;
 989                 inet_putpeer(peer);
 990         }
 991         if (send)
 992                 icmp_send(skb, ICMP_DEST_UNREACH, code, 0);
 993
 994 out:    kfree_skb(skb);
 995         return 0;
 996 }
 997
 998 static void __ip_rt_update_pmtu(struct rtable *rt, struct flowi4 *fl4, u32 mtu)
 999 {
1000         struct dst_entry *dst = &rt->dst;
1001         struct fib_result res;
1002
1003         if (dst_metric_locked(dst, RTAX_MTU))
1004                 return;
1005
1006         if (ipv4_mtu(dst) < mtu)
1007                 return;
1008
1009         if (mtu < ip_rt_min_pmtu)
1010                 mtu = ip_rt_min_pmtu;
1011
1012         if (rt->rt_pmtu == mtu &&
1013             time_before(jiffies, dst->expires - ip_rt_mtu_expires / 2))
1014                 return;
1015
1016         rcu_read_lock();
1017         if (fib_lookup(dev_net(dst->dev), fl4, &res, 0) == 0) {
1018                 struct fib_nh *nh = &FIB_RES_NH(res);
1019
1020                 update_or_create_fnhe(nh, fl4->daddr, 0, mtu,
1021                                       jiffies + ip_rt_mtu_expires);
1022         }
1023         rcu_read_unlock();
1024 }
1025
1026 static void ip_rt_update_pmtu(struct dst_entry *dst, struct sock *sk,
1027                               struct sk_buff *skb, u32 mtu)
1028 {
1029         struct rtable *rt = (struct rtable *) dst;
1030         struct flowi4 fl4;
1031
1032         ip_rt_build_flow_key(&fl4, sk, skb);
1033         __ip_rt_update_pmtu(rt, &fl4, mtu);
1034 }
1035
1036 void ipv4_update_pmtu(struct sk_buff *skb, struct net *net, u32 mtu,
1037                       int oif, u32 mark, u8 protocol, int flow_flags)
1038 {
1039         const struct iphdr *iph = (const struct iphdr *) skb->data;
1040         struct flowi4 fl4;
1041         struct rtable *rt;
1042
1043         if (!mark)
1044                 mark = IP4_REPLY_MARK(net, skb->mark);
1045
1046         __build_flow_key(net, &fl4, NULL, iph, oif,
1047                          RT_TOS(iph->tos), protocol, mark, flow_flags);
1048         rt = __ip_route_output_key(net, &fl4);
1049         if (!IS_ERR(rt)) {
1050                 __ip_rt_update_pmtu(rt, &fl4, mtu);
1051                 ip_rt_put(rt);
1052         }
1053 }
1054 EXPORT_SYMBOL_GPL(ipv4_update_pmtu);
1055
1056 static void __ipv4_sk_update_pmtu(struct sk_buff *skb, struct sock *sk, u32 mtu)
1057 {
1058         const struct iphdr *iph = (const struct iphdr *) skb->data;
1059         struct flowi4 fl4;
1060         struct rtable *rt;
1061
1062         __build_flow_key(sock_net(sk), &fl4, sk, iph, 0, 0, 0, 0, 0);
1063
1064         if (!fl4.flowi4_mark)
1065                 fl4.flowi4_mark = IP4_REPLY_MARK(sock_net(sk), skb->mark);
1066
1067         rt = __ip_route_output_key(sock_net(sk), &fl4);
1068         if (!IS_ERR(rt)) {
1069                 __ip_rt_update_pmtu(rt, &fl4, mtu);
1070                 ip_rt_put(rt);
1071         }
1072 }
1073
1074 void ipv4_sk_update_pmtu(struct sk_buff *skb, struct sock *sk, u32 mtu)
1075 {
1076         const struct iphdr *iph = (const struct iphdr *) skb->data;
1077         struct flowi4 fl4;
1078         struct rtable *rt;
1079         struct dst_entry *odst = NULL;
1080         bool new = false;
1081         struct net *net = sock_net(sk);
1082
1083         bh_lock_sock(sk);
1084
1085         if (!ip_sk_accept_pmtu(sk))
1086                 goto out;
1087
1088         odst = sk_dst_get(sk);
1089
1090         if (sock_owned_by_user(sk) || !odst) {
1091                 __ipv4_sk_update_pmtu(skb, sk, mtu);
1092                 goto out;
1093         }
1094
1095         __build_flow_key(net, &fl4, sk, iph, 0, 0, 0, 0, 0);
1096
1097         rt = (struct rtable *)odst;
1098         if (odst->obsolete && !odst->ops->check(odst, 0)) {
1099                 rt = ip_route_output_flow(sock_net(sk), &fl4, sk);
1100                 if (IS_ERR(rt))
1101                         goto out;
1102
1103                 new = true;
1104         }
1105
1106         __ip_rt_update_pmtu((struct rtable *) rt->dst.path, &fl4, mtu);
1107
1108         if (!dst_check(&rt->dst, 0)) {
1109                 if (new)
1110                         dst_release(&rt->dst);
1111
1112                 rt = ip_route_output_flow(sock_net(sk), &fl4, sk);
1113                 if (IS_ERR(rt))
1114                         goto out;
1115
1116                 new = true;
1117         }
1118
1119         if (new)
1120                 sk_dst_set(sk, &rt->dst);
1121
1122 out:
1123         bh_unlock_sock(sk);
1124         dst_release(odst);
1125 }
1126 EXPORT_SYMBOL_GPL(ipv4_sk_update_pmtu);
1127
1128 void ipv4_redirect(struct sk_buff *skb, struct net *net,
1129                    int oif, u32 mark, u8 protocol, int flow_flags)
1130 {
1131         const struct iphdr *iph = (const struct iphdr *) skb->data;
1132         struct flowi4 fl4;
1133         struct rtable *rt;
1134
1135         __build_flow_key(net, &fl4, NULL, iph, oif,
1136                          RT_TOS(iph->tos), protocol, mark, flow_flags);
1137         rt = __ip_route_output_key(net, &fl4);
1138         if (!IS_ERR(rt)) {
1139                 __ip_do_redirect(rt, skb, &fl4, false);
1140                 ip_rt_put(rt);
1141         }
1142 }
1143 EXPORT_SYMBOL_GPL(ipv4_redirect);
1144
1145 void ipv4_sk_redirect(struct sk_buff *skb, struct sock *sk)
1146 {
1147         const struct iphdr *iph = (const struct iphdr *) skb->data;
1148         struct flowi4 fl4;
1149         struct rtable *rt;
1150         struct net *net = sock_net(sk);
1151
1152         __build_flow_key(net, &fl4, sk, iph, 0, 0, 0, 0, 0);
1153         rt = __ip_route_output_key(net, &fl4);
1154         if (!IS_ERR(rt)) {
1155                 __ip_do_redirect(rt, skb, &fl4, false);
1156                 ip_rt_put(rt);
1157         }
1158 }
1159 EXPORT_SYMBOL_GPL(ipv4_sk_redirect);
1160
1161 static struct dst_entry *ipv4_dst_check(struct dst_entry *dst, u32 cookie)
1162 {
1163         struct rtable *rt = (struct rtable *) dst;
1164
1165         /* All IPV4 dsts are created with ->obsolete set to the value
1166          * DST_OBSOLETE_FORCE_CHK which forces validation calls down
1167          * into this function always.
1168          *
1169          * When a PMTU/redirect information update invalidates a route,
1170          * this is indicated by setting obsolete to DST_OBSOLETE_KILL or
1171          * DST_OBSOLETE_DEAD by dst_free().
1172          */
1173         if (dst->obsolete != DST_OBSOLETE_FORCE_CHK || rt_is_expired(rt))
1174                 return NULL;
1175         return dst;
1176 }
1177
1178 static void ipv4_link_failure(struct sk_buff *skb)
1179 {
1180         struct rtable *rt;
1181
1182         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_HOST_UNREACH, 0);
1183
1184         rt = skb_rtable(skb);
1185         if (rt)
1186                 dst_set_expires(&rt->dst, 0);
1187 }
1188
1189 static int ip_rt_bug(struct net *net, struct sock *sk, struct sk_buff *skb)
1190 {
1191         pr_debug("%s: %pI4 -> %pI4, %s\n",
1192                  __func__, &ip_hdr(skb)->saddr, &ip_hdr(skb)->daddr,
1193                  skb->dev ? skb->dev->name : "?");
1194         kfree_skb(skb);
1195         WARN_ON(1);
1196         return 0;
1197 }
1198
1199 /*
1200    We do not cache source address of outgoing interface,
1201    because it is used only by IP RR, TS and SRR options,
1202    so that it out of fast path.
1203
1204    BTW remember: "addr" is allowed to be not aligned
1205    in IP options!
1206  */
1207
1208 void ip_rt_get_source(u8 *addr, struct sk_buff *skb, struct rtable *rt)
1209 {
1210         __be32 src;
1211
1212         if (rt_is_output_route(rt))
1213                 src = ip_hdr(skb)->saddr;
1214         else {
1215                 struct fib_result res;
1216                 struct flowi4 fl4;
1217                 struct iphdr *iph;
1218
1219                 iph = ip_hdr(skb);
1220
1221                 memset(&fl4, 0, sizeof(fl4));
1222                 fl4.daddr = iph->daddr;
1223                 fl4.saddr = iph->saddr;
1224                 fl4.flowi4_tos = RT_TOS(iph->tos);
1225                 fl4.flowi4_oif = rt->dst.dev->ifindex;
1226                 fl4.flowi4_iif = skb->dev->ifindex;
1227                 fl4.flowi4_mark = skb->mark;
1228
1229                 rcu_read_lock();
1230                 if (fib_lookup(dev_net(rt->dst.dev), &fl4, &res, 0) == 0)
1231                         src = FIB_RES_PREFSRC(dev_net(rt->dst.dev), res);
1232                 else
1233                         src = inet_select_addr(rt->dst.dev,
1234                                                rt_nexthop(rt, iph->daddr),
1235                                                RT_SCOPE_UNIVERSE);
1236                 rcu_read_unlock();
1237         }
1238         memcpy(addr, &src, 4);
1239 }
1240
1241 #ifdef CONFIG_IP_ROUTE_CLASSID
1242 static void set_class_tag(struct rtable *rt, u32 tag)
1243 {
1244         if (!(rt->dst.tclassid & 0xFFFF))
1245                 rt->dst.tclassid |= tag & 0xFFFF;
1246         if (!(rt->dst.tclassid & 0xFFFF0000))
1247                 rt->dst.tclassid |= tag & 0xFFFF0000;
1248 }
1249 #endif
1250
1251 static unsigned int ipv4_default_advmss(const struct dst_entry *dst)
1252 {
1253         unsigned int header_size = sizeof(struct tcphdr) + sizeof(struct iphdr);
1254         unsigned int advmss = max_t(unsigned int, dst->dev->mtu - header_size,
1255                                     ip_rt_min_advmss);
1256
1257         return min(advmss, IPV4_MAX_PMTU - header_size);
1258 }
1259
1260 static unsigned int ipv4_mtu(const struct dst_entry *dst)
1261 {
1262         const struct rtable *rt = (const struct rtable *) dst;
1263         unsigned int mtu = rt->rt_pmtu;
1264
1265         if (!mtu || time_after_eq(jiffies, rt->dst.expires))
1266                 mtu = dst_metric_raw(dst, RTAX_MTU);
1267
1268         if (mtu)
1269                 return mtu;
1270
1271         mtu = dst->dev->mtu;
1272
1273         if (unlikely(dst_metric_locked(dst, RTAX_MTU))) {
1274                 if (rt->rt_uses_gateway && mtu > 576)
1275                         mtu = 576;
1276         }
1277
1278         mtu = min_t(unsigned int, mtu, IP_MAX_MTU);
1279
1280         return mtu - lwtunnel_headroom(dst->lwtstate, mtu);
1281 }
1282
1283 static struct fib_nh_exception *find_exception(struct fib_nh *nh, __be32 daddr)
1284 {
1285         struct fnhe_hash_bucket *hash = rcu_dereference(nh->nh_exceptions);
1286         struct fib_nh_exception *fnhe;
1287         u32 hval;
1288
1289         if (!hash)
1290                 return NULL;
1291
1292         hval = fnhe_hashfun(daddr);
1293
1294         for (fnhe = rcu_dereference(hash[hval].chain); fnhe;
1295              fnhe = rcu_dereference(fnhe->fnhe_next)) {
1296                 if (fnhe->fnhe_daddr == daddr)
1297                         return fnhe;
1298         }
1299         return NULL;
1300 }
1301
1302 static bool rt_bind_exception(struct rtable *rt, struct fib_nh_exception *fnhe,
1303                               __be32 daddr)
1304 {
1305         bool ret = false;
1306
1307         spin_lock_bh(&fnhe_lock);
1308
1309         if (daddr == fnhe->fnhe_daddr) {
1310                 struct rtable __rcu **porig;
1311                 struct rtable *orig;
1312                 int genid = fnhe_genid(dev_net(rt->dst.dev));
1313
1314                 if (rt_is_input_route(rt))
1315                         porig = &fnhe->fnhe_rth_input;
1316                 else
1317                         porig = &fnhe->fnhe_rth_output;
1318                 orig = rcu_dereference(*porig);
1319
1320                 if (fnhe->fnhe_genid != genid) {
1321                         fnhe->fnhe_genid = genid;
1322                         fnhe->fnhe_gw = 0;
1323                         fnhe->fnhe_pmtu = 0;
1324                         fnhe->fnhe_expires = 0;
1325                         fnhe_flush_routes(fnhe);
1326                         orig = NULL;
1327                 }
1328                 fill_route_from_fnhe(rt, fnhe);
1329                 if (!rt->rt_gateway)
1330                         rt->rt_gateway = daddr;
1331
1332                 if (!(rt->dst.flags & DST_NOCACHE)) {
1333                         rcu_assign_pointer(*porig, rt);
1334                         if (orig)
1335                                 rt_free(orig);
1336                         ret = true;
1337                 }
1338
1339                 fnhe->fnhe_stamp = jiffies;
1340         }
1341         spin_unlock_bh(&fnhe_lock);
1342
1343         return ret;
1344 }
1345
1346 static bool rt_cache_route(struct fib_nh *nh, struct rtable *rt)
1347 {
1348         struct rtable *orig, *prev, **p;
1349         bool ret = true;
1350
1351         if (rt_is_input_route(rt)) {
1352                 p = (struct rtable **)&nh->nh_rth_input;
1353         } else {
1354                 p = (struct rtable **)raw_cpu_ptr(nh->nh_pcpu_rth_output);
1355         }
1356         orig = *p;
1357
1358         prev = cmpxchg(p, orig, rt);
1359         if (prev == orig) {
1360                 if (orig)
1361                         rt_free(orig);
1362         } else
1363                 ret = false;
1364
1365         return ret;
1366 }
1367
1368 struct uncached_list {
1369         spinlock_t              lock;
1370         struct list_head        head;
1371 };
1372
1373 static DEFINE_PER_CPU_ALIGNED(struct uncached_list, rt_uncached_list);
1374
1375 static void rt_add_uncached_list(struct rtable *rt)
1376 {
1377         struct uncached_list *ul = raw_cpu_ptr(&rt_uncached_list);
1378
1379         rt->rt_uncached_list = ul;
1380
1381         spin_lock_bh(&ul->lock);
1382         list_add_tail(&rt->rt_uncached, &ul->head);
1383         spin_unlock_bh(&ul->lock);
1384 }
1385
1386 static void ipv4_dst_destroy(struct dst_entry *dst)
1387 {
1388         struct rtable *rt = (struct rtable *) dst;
1389
1390         if (!list_empty(&rt->rt_uncached)) {
1391                 struct uncached_list *ul = rt->rt_uncached_list;
1392
1393                 spin_lock_bh(&ul->lock);
1394                 list_del(&rt->rt_uncached);
1395                 spin_unlock_bh(&ul->lock);
1396         }
1397 }
1398
1399 void rt_flush_dev(struct net_device *dev)
1400 {
1401         struct net *net = dev_net(dev);
1402         struct rtable *rt;
1403         int cpu;
1404
1405         for_each_possible_cpu(cpu) {
1406                 struct uncached_list *ul = &per_cpu(rt_uncached_list, cpu);
1407
1408                 spin_lock_bh(&ul->lock);
1409                 list_for_each_entry(rt, &ul->head, rt_uncached) {
1410                         if (rt->dst.dev != dev)
1411                                 continue;
1412                         rt->dst.dev = net->loopback_dev;
1413                         dev_hold(rt->dst.dev);
1414                         dev_put(dev);
1415                 }
1416                 spin_unlock_bh(&ul->lock);
1417         }
1418 }
1419
1420 static bool rt_cache_valid(const struct rtable *rt)
1421 {
1422         return  rt &&
1423                 rt->dst.obsolete == DST_OBSOLETE_FORCE_CHK &&
1424                 !rt_is_expired(rt);
1425 }
1426
1427 static void rt_set_nexthop(struct rtable *rt, __be32 daddr,
1428                            const struct fib_result *res,
1429                            struct fib_nh_exception *fnhe,
1430                            struct fib_info *fi, u16 type, u32 itag)
1431 {
1432         bool cached = false;
1433
1434         if (fi) {
1435                 struct fib_nh *nh = &FIB_RES_NH(*res);
1436
1437                 if (nh->nh_gw && nh->nh_scope == RT_SCOPE_LINK) {
1438                         rt->rt_gateway = nh->nh_gw;
1439                         rt->rt_uses_gateway = 1;
1440                 }
1441                 dst_init_metrics(&rt->dst, fi->fib_metrics, true);
1442 #ifdef CONFIG_IP_ROUTE_CLASSID
1443                 rt->dst.tclassid = nh->nh_tclassid;
1444 #endif
1445                 rt->dst.lwtstate = lwtstate_get(nh->nh_lwtstate);
1446                 if (unlikely(fnhe))
1447                         cached = rt_bind_exception(rt, fnhe, daddr);
1448                 else if (!(rt->dst.flags & DST_NOCACHE))
1449                         cached = rt_cache_route(nh, rt);
1450                 if (unlikely(!cached)) {
1451                         /* Routes we intend to cache in nexthop exception or
1452                          * FIB nexthop have the DST_NOCACHE bit clear.
1453                          * However, if we are unsuccessful at storing this
1454                          * route into the cache we really need to set it.
1455                          */
1456                         rt->dst.flags |= DST_NOCACHE;
1457                         if (!rt->rt_gateway)
1458                                 rt->rt_gateway = daddr;
1459                         rt_add_uncached_list(rt);
1460                 }
1461         } else
1462                 rt_add_uncached_list(rt);
1463
1464 #ifdef CONFIG_IP_ROUTE_CLASSID
1465 #ifdef CONFIG_IP_MULTIPLE_TABLES
1466         set_class_tag(rt, res->tclassid);
1467 #endif
1468         set_class_tag(rt, itag);
1469 #endif
1470 }
1471
1472 struct rtable *rt_dst_alloc(struct net_device *dev,
1473                             unsigned int flags, u16 type,
1474                             bool nopolicy, bool noxfrm, bool will_cache)
1475 {
1476         struct rtable *rt;
1477
1478         rt = dst_alloc(&ipv4_dst_ops, dev, 1, DST_OBSOLETE_FORCE_CHK,
1479                        (will_cache ? 0 : (DST_HOST | DST_NOCACHE)) |
1480                        (nopolicy ? DST_NOPOLICY : 0) |
1481                        (noxfrm ? DST_NOXFRM : 0));
1482
1483         if (rt) {
1484                 rt->rt_genid = rt_genid_ipv4(dev_net(dev));
1485                 rt->rt_flags = flags;
1486                 rt->rt_type = type;
1487                 rt->rt_is_input = 0;
1488                 rt->rt_iif = 0;
1489                 rt->rt_pmtu = 0;
1490                 rt->rt_gateway = 0;
1491                 rt->rt_uses_gateway = 0;
1492                 rt->rt_table_id = 0;
1493                 INIT_LIST_HEAD(&rt->rt_uncached);
1494
1495                 rt->dst.output = ip_output;
1496                 if (flags & RTCF_LOCAL)
1497                         rt->dst.input = ip_local_deliver;
1498         }
1499
1500         return rt;
1501 }
1502 EXPORT_SYMBOL(rt_dst_alloc);
1503
1504 /* called in rcu_read_lock() section */
1505 static int ip_route_input_mc(struct sk_buff *skb, __be32 daddr, __be32 saddr,
1506                                 u8 tos, struct net_device *dev, int our)
1507 {
1508         struct rtable *rth;
1509         struct in_device *in_dev = __in_dev_get_rcu(dev);
1510         unsigned int flags = RTCF_MULTICAST;
1511         u32 itag = 0;
1512         int err;
1513
1514         /* Primary sanity checks. */
1515
1516         if (!in_dev)
1517                 return -EINVAL;
1518
1519         if (ipv4_is_multicast(saddr) || ipv4_is_lbcast(saddr) ||
1520             skb->protocol != htons(ETH_P_IP))
1521                 goto e_inval;
1522
1523         if (ipv4_is_loopback(saddr) && !IN_DEV_ROUTE_LOCALNET(in_dev))
1524                 goto e_inval;
1525
1526         if (ipv4_is_zeronet(saddr)) {
1527                 if (!ipv4_is_local_multicast(daddr))
1528                         goto e_inval;
1529         } else {
1530                 err = fib_validate_source(skb, saddr, 0, tos, 0, dev,
1531                                           in_dev, &itag);
1532                 if (err < 0)
1533                         goto e_err;
1534         }
1535         if (our)
1536                 flags |= RTCF_LOCAL;
1537
1538         rth = rt_dst_alloc(dev_net(dev)->loopback_dev, flags, RTN_MULTICAST,
1539                            IN_DEV_CONF_GET(in_dev, NOPOLICY), false, false);
1540         if (!rth)
1541                 goto e_nobufs;
1542
1543 #ifdef CONFIG_IP_ROUTE_CLASSID
1544         rth->dst.tclassid = itag;
1545 #endif
1546         rth->dst.output = ip_rt_bug;
1547         rth->rt_is_input= 1;
1548
1549 #ifdef CONFIG_IP_MROUTE
1550         if (!ipv4_is_local_multicast(daddr) && IN_DEV_MFORWARD(in_dev))
1551                 rth->dst.input = ip_mr_input;
1552 #endif
1553         RT_CACHE_STAT_INC(in_slow_mc);
1554
1555         skb_dst_set(skb, &rth->dst);
1556         return 0;
1557
1558 e_nobufs:
1559         return -ENOBUFS;
1560 e_inval:
1561         return -EINVAL;
1562 e_err:
1563         return err;
1564 }
1565
1566
1567 static void ip_handle_martian_source(struct net_device *dev,
1568                                      struct in_device *in_dev,
1569                                      struct sk_buff *skb,
1570                                      __be32 daddr,
1571                                      __be32 saddr)
1572 {
1573         RT_CACHE_STAT_INC(in_martian_src);
1574 #ifdef CONFIG_IP_ROUTE_VERBOSE
1575         if (IN_DEV_LOG_MARTIANS(in_dev) && net_ratelimit()) {
1576                 /*
1577                  *      RFC1812 recommendation, if source is martian,
1578                  *      the only hint is MAC header.
1579                  */
1580                 pr_warn("martian source %pI4 from %pI4, on dev %s\n",
1581                         &daddr, &saddr, dev->name);
1582                 if (dev->hard_header_len && skb_mac_header_was_set(skb)) {
1583                         print_hex_dump(KERN_WARNING, "ll header: ",
1584                                        DUMP_PREFIX_OFFSET, 16, 1,
1585                                        skb_mac_header(skb),
1586                                        dev->hard_header_len, true);
1587                 }
1588         }
1589 #endif
1590 }
1591
1592 static void ip_del_fnhe(struct fib_nh *nh, __be32 daddr)
1593 {
1594         struct fnhe_hash_bucket *hash;
1595         struct fib_nh_exception *fnhe, __rcu **fnhe_p;
1596         u32 hval = fnhe_hashfun(daddr);
1597
1598         spin_lock_bh(&fnhe_lock);
1599
1600         hash = rcu_dereference_protected(nh->nh_exceptions,
1601                                          lockdep_is_held(&fnhe_lock));
1602         hash += hval;
1603
1604         fnhe_p = &hash->chain;
1605         fnhe = rcu_dereference_protected(*fnhe_p, lockdep_is_held(&fnhe_lock));
1606         while (fnhe) {
1607                 if (fnhe->fnhe_daddr == daddr) {
1608                         rcu_assign_pointer(*fnhe_p, rcu_dereference_protected(
1609                                 fnhe->fnhe_next, lockdep_is_held(&fnhe_lock)));
1610                         fnhe_flush_routes(fnhe);
1611                         kfree_rcu(fnhe, rcu);
1612                         break;
1613                 }
1614                 fnhe_p = &fnhe->fnhe_next;
1615                 fnhe = rcu_dereference_protected(fnhe->fnhe_next,
1616                                                  lockdep_is_held(&fnhe_lock));
1617         }
1618
1619         spin_unlock_bh(&fnhe_lock);
1620 }
1621
1622 static void set_lwt_redirect(struct rtable *rth)
1623 {
1624         if (lwtunnel_output_redirect(rth->dst.lwtstate)) {
1625                 rth->dst.lwtstate->orig_output = rth->dst.output;
1626                 rth->dst.output = lwtunnel_output;
1627         }
1628
1629         if (lwtunnel_input_redirect(rth->dst.lwtstate)) {
1630                 rth->dst.lwtstate->orig_input = rth->dst.input;
1631                 rth->dst.input = lwtunnel_input;
1632         }
1633 }
1634
1635 /* called in rcu_read_lock() section */
1636 static int __mkroute_input(struct sk_buff *skb,
1637                            const struct fib_result *res,
1638                            struct in_device *in_dev,
1639                            __be32 daddr, __be32 saddr, u32 tos)
1640 {
1641         struct fib_nh_exception *fnhe;
1642         struct rtable *rth;
1643         int err;
1644         struct in_device *out_dev;
1645         bool do_cache;
1646         u32 itag = 0;
1647
1648         /* get a working reference to the output device */
1649         out_dev = __in_dev_get_rcu(FIB_RES_DEV(*res));
1650         if (!out_dev) {
1651                 net_crit_ratelimited("Bug in ip_route_input_slow(). Please report.\n");
1652                 return -EINVAL;
1653         }
1654
1655         err = fib_validate_source(skb, saddr, daddr, tos, FIB_RES_OIF(*res),
1656                                   in_dev->dev, in_dev, &itag);
1657         if (err < 0) {
1658                 ip_handle_martian_source(in_dev->dev, in_dev, skb, daddr,
1659                                          saddr);
1660
1661                 goto cleanup;
1662         }
1663
1664         do_cache = res->fi && !itag;
1665         if (out_dev == in_dev && err && IN_DEV_TX_REDIRECTS(out_dev) &&
1666             skb->protocol == htons(ETH_P_IP) &&
1667             (IN_DEV_SHARED_MEDIA(out_dev) ||
1668              inet_addr_onlink(out_dev, saddr, FIB_RES_GW(*res))))
1669                 IPCB(skb)->flags |= IPSKB_DOREDIRECT;
1670
1671         if (skb->protocol != htons(ETH_P_IP)) {
1672                 /* Not IP (i.e. ARP). Do not create route, if it is
1673                  * invalid for proxy arp. DNAT routes are always valid.
1674                  *
1675                  * Proxy arp feature have been extended to allow, ARP
1676                  * replies back to the same interface, to support
1677                  * Private VLAN switch technologies. See arp.c.
1678                  */
1679                 if (out_dev == in_dev &&
1680                     IN_DEV_PROXY_ARP_PVLAN(in_dev) == 0) {
1681                         err = -EINVAL;
1682                         goto cleanup;
1683                 }
1684         }
1685
1686         fnhe = find_exception(&FIB_RES_NH(*res), daddr);
1687         if (do_cache) {
1688                 if (fnhe) {
1689                         rth = rcu_dereference(fnhe->fnhe_rth_input);
1690                         if (rth && rth->dst.expires &&
1691                             time_after(jiffies, rth->dst.expires)) {
1692                                 ip_del_fnhe(&FIB_RES_NH(*res), daddr);
1693                                 fnhe = NULL;
1694                         } else {
1695                                 goto rt_cache;
1696                         }
1697                 }
1698
1699                 rth = rcu_dereference(FIB_RES_NH(*res).nh_rth_input);
1700
1701 rt_cache:
1702                 if (rt_cache_valid(rth)) {
1703                         skb_dst_set_noref(skb, &rth->dst);
1704                         goto out;
1705                 }
1706         }
1707
1708         rth = rt_dst_alloc(out_dev->dev, 0, res->type,
1709                            IN_DEV_CONF_GET(in_dev, NOPOLICY),
1710                            IN_DEV_CONF_GET(out_dev, NOXFRM), do_cache);
1711         if (!rth) {
1712                 err = -ENOBUFS;
1713                 goto cleanup;
1714         }
1715
1716         rth->rt_is_input = 1;
1717         if (res->table)
1718                 rth->rt_table_id = res->table->tb_id;
1719         RT_CACHE_STAT_INC(in_slow_tot);
1720
1721         rth->dst.input = ip_forward;
1722
1723         rt_set_nexthop(rth, daddr, res, fnhe, res->fi, res->type, itag);
1724         set_lwt_redirect(rth);
1725         skb_dst_set(skb, &rth->dst);
1726 out:
1727         err = 0;
1728  cleanup:
1729         return err;
1730 }
1731
1732 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1733 /* To make ICMP packets follow the right flow, the multipath hash is
1734  * calculated from the inner IP addresses.
1735  */
1736 static void ip_multipath_l3_keys(const struct sk_buff *skb,
1737                                  struct flow_keys *hash_keys)
1738 {
1739         const struct iphdr *outer_iph = ip_hdr(skb);
1740         const struct iphdr *inner_iph;
1741         const struct icmphdr *icmph;
1742         struct iphdr _inner_iph;
1743         struct icmphdr _icmph;
1744
1745         hash_keys->addrs.v4addrs.src = outer_iph->saddr;
1746         hash_keys->addrs.v4addrs.dst = outer_iph->daddr;
1747         if (likely(outer_iph->protocol != IPPROTO_ICMP))
1748                 return;
1749
1750         if (unlikely((outer_iph->frag_off & htons(IP_OFFSET)) != 0))
1751                 return;
1752
1753         icmph = skb_header_pointer(skb, outer_iph->ihl * 4, sizeof(_icmph),
1754                                    &_icmph);
1755         if (!icmph)
1756                 return;
1757
1758         if (icmph->type != ICMP_DEST_UNREACH &&
1759             icmph->type != ICMP_REDIRECT &&
1760             icmph->type != ICMP_TIME_EXCEEDED &&
1761             icmph->type != ICMP_PARAMETERPROB)
1762                 return;
1763
1764         inner_iph = skb_header_pointer(skb,
1765                                        outer_iph->ihl * 4 + sizeof(_icmph),
1766                                        sizeof(_inner_iph), &_inner_iph);
1767         if (!inner_iph)
1768                 return;
1769         hash_keys->addrs.v4addrs.src = inner_iph->saddr;
1770         hash_keys->addrs.v4addrs.dst = inner_iph->daddr;
1771 }
1772
1773 /* if skb is set it will be used and fl4 can be NULL */
1774 int fib_multipath_hash(const struct fib_info *fi, const struct flowi4 *fl4,
1775                        const struct sk_buff *skb)
1776 {
1777         struct net *net = fi->fib_net;
1778         struct flow_keys hash_keys;
1779         u32 mhash;
1780
1781         switch (net->ipv4.sysctl_fib_multipath_hash_policy) {
1782         case 0:
1783                 memset(&hash_keys, 0, sizeof(hash_keys));
1784                 hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS;
1785                 if (skb) {
1786                         ip_multipath_l3_keys(skb, &hash_keys);
1787                 } else {
1788                         hash_keys.addrs.v4addrs.src = fl4->saddr;
1789                         hash_keys.addrs.v4addrs.dst = fl4->daddr;
1790                 }
1791                 break;
1792         case 1:
1793                 /* skb is currently provided only when forwarding */
1794                 if (skb) {
1795                         unsigned int flag = FLOW_DISSECTOR_F_STOP_AT_ENCAP;
1796                         struct flow_keys keys;
1797
1798                         /* short-circuit if we already have L4 hash present */
1799                         if (skb->l4_hash)
1800                                 return skb_get_hash_raw(skb) >> 1;
1801                         memset(&hash_keys, 0, sizeof(hash_keys));
1802                         skb_flow_dissect_flow_keys(skb, &keys, flag);
1803                         hash_keys.addrs.v4addrs.src = keys.addrs.v4addrs.src;
1804                         hash_keys.addrs.v4addrs.dst = keys.addrs.v4addrs.dst;
1805                         hash_keys.ports.src = keys.ports.src;
1806                         hash_keys.ports.dst = keys.ports.dst;
1807                         hash_keys.basic.ip_proto = keys.basic.ip_proto;
1808                 } else {
1809                         memset(&hash_keys, 0, sizeof(hash_keys));
1810                         hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS;
1811                         hash_keys.addrs.v4addrs.src = fl4->saddr;
1812                         hash_keys.addrs.v4addrs.dst = fl4->daddr;
1813                         hash_keys.ports.src = fl4->fl4_sport;
1814                         hash_keys.ports.dst = fl4->fl4_dport;
1815                         hash_keys.basic.ip_proto = fl4->flowi4_proto;
1816                 }
1817                 break;
1818         }
1819         mhash = flow_hash_from_keys(&hash_keys);
1820
1821         return mhash >> 1;
1822 }
1823 EXPORT_SYMBOL_GPL(fib_multipath_hash);
1824 #endif /* CONFIG_IP_ROUTE_MULTIPATH */
1825
1826 static int ip_mkroute_input(struct sk_buff *skb,
1827                             struct fib_result *res,
1828                             struct in_device *in_dev,
1829                             __be32 daddr, __be32 saddr, u32 tos)
1830 {
1831 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1832         if (res->fi && res->fi->fib_nhs > 1) {
1833                 int h = fib_multipath_hash(res->fi, NULL, skb);
1834
1835                 fib_select_multipath(res, h);
1836         }
1837 #endif
1838
1839         /* create a routing cache entry */
1840         return __mkroute_input(skb, res, in_dev, daddr, saddr, tos);
1841 }
1842
1843 /*
1844  *      NOTE. We drop all the packets that has local source
1845  *      addresses, because every properly looped back packet
1846  *      must have correct destination already attached by output routine.
1847  *
1848  *      Such approach solves two big problems:
1849  *      1. Not simplex devices are handled properly.
1850  *      2. IP spoofing attempts are filtered with 100% of guarantee.
1851  *      called with rcu_read_lock()
1852  */
1853
1854 static int ip_route_input_slow(struct sk_buff *skb, __be32 daddr, __be32 saddr,
1855                                u8 tos, struct net_device *dev)
1856 {
1857         struct fib_result res;
1858         struct in_device *in_dev = __in_dev_get_rcu(dev);
1859         struct ip_tunnel_info *tun_info;
1860         struct flowi4   fl4;
1861         unsigned int    flags = 0;
1862         u32             itag = 0;
1863         struct rtable   *rth;
1864         int             err = -EINVAL;
1865         struct net    *net = dev_net(dev);
1866         bool do_cache;
1867
1868         /* IP on this device is disabled. */
1869
1870         if (!in_dev)
1871                 goto out;
1872
1873         /* Check for the most weird martians, which can be not detected
1874            by fib_lookup.
1875          */
1876
1877         tun_info = skb_tunnel_info(skb);
1878         if (tun_info && !(tun_info->mode & IP_TUNNEL_INFO_TX))
1879                 fl4.flowi4_tun_key.tun_id = tun_info->key.tun_id;
1880         else
1881                 fl4.flowi4_tun_key.tun_id = 0;
1882         skb_dst_drop(skb);
1883
1884         if (ipv4_is_multicast(saddr) || ipv4_is_lbcast(saddr))
1885                 goto martian_source;
1886
1887         res.fi = NULL;
1888         res.table = NULL;
1889         if (ipv4_is_lbcast(daddr) || (saddr == 0 && daddr == 0))
1890                 goto brd_input;
1891
1892         /* Accept zero addresses only to limited broadcast;
1893          * I even do not know to fix it or not. Waiting for complains :-)
1894          */
1895         if (ipv4_is_zeronet(saddr))
1896                 goto martian_source;
1897
1898         if (ipv4_is_zeronet(daddr))
1899                 goto martian_destination;
1900
1901         /* Following code try to avoid calling IN_DEV_NET_ROUTE_LOCALNET(),
1902          * and call it once if daddr or/and saddr are loopback addresses
1903          */
1904         if (ipv4_is_loopback(daddr)) {
1905                 if (!IN_DEV_NET_ROUTE_LOCALNET(in_dev, net))
1906                         goto martian_destination;
1907         } else if (ipv4_is_loopback(saddr)) {
1908                 if (!IN_DEV_NET_ROUTE_LOCALNET(in_dev, net))
1909                         goto martian_source;
1910         }
1911
1912         /*
1913          *      Now we are ready to route packet.
1914          */
1915         fl4.flowi4_oif = 0;
1916         fl4.flowi4_iif = dev->ifindex;
1917         fl4.flowi4_mark = skb->mark;
1918         fl4.flowi4_tos = tos;
1919         fl4.flowi4_scope = RT_SCOPE_UNIVERSE;
1920         fl4.flowi4_flags = 0;
1921         fl4.daddr = daddr;
1922         fl4.saddr = saddr;
1923         fl4.flowi4_uid = sock_net_uid(net, NULL);
1924         err = fib_lookup(net, &fl4, &res, 0);
1925         if (err != 0) {
1926                 if (!IN_DEV_FORWARD(in_dev))
1927                         err = -EHOSTUNREACH;
1928                 goto no_route;
1929         }
1930
1931         if (res.type == RTN_BROADCAST)
1932                 goto brd_input;
1933
1934         if (res.type == RTN_LOCAL) {
1935                 err = fib_validate_source(skb, saddr, daddr, tos,
1936                                           0, dev, in_dev, &itag);
1937                 if (err < 0)
1938                         goto martian_source;
1939                 goto local_input;
1940         }
1941
1942         if (!IN_DEV_FORWARD(in_dev)) {
1943                 err = -EHOSTUNREACH;
1944                 goto no_route;
1945         }
1946         if (res.type != RTN_UNICAST)
1947                 goto martian_destination;
1948
1949         err = ip_mkroute_input(skb, &res, in_dev, daddr, saddr, tos);
1950 out:    return err;
1951
1952 brd_input:
1953         if (skb->protocol != htons(ETH_P_IP))
1954                 goto e_inval;
1955
1956         if (!ipv4_is_zeronet(saddr)) {
1957                 err = fib_validate_source(skb, saddr, 0, tos, 0, dev,
1958                                           in_dev, &itag);
1959                 if (err < 0)
1960                         goto martian_source;
1961         }
1962         flags |= RTCF_BROADCAST;
1963         res.type = RTN_BROADCAST;
1964         RT_CACHE_STAT_INC(in_brd);
1965
1966 local_input:
1967         do_cache = false;
1968         if (res.fi) {
1969                 if (!itag) {
1970                         rth = rcu_dereference(FIB_RES_NH(res).nh_rth_input);
1971                         if (rt_cache_valid(rth)) {
1972                                 skb_dst_set_noref(skb, &rth->dst);
1973                                 err = 0;
1974                                 goto out;
1975                         }
1976                         do_cache = true;
1977                 }
1978         }
1979
1980         rth = rt_dst_alloc(l3mdev_master_dev_rcu(dev) ? : net->loopback_dev,
1981                            flags | RTCF_LOCAL, res.type,
1982                            IN_DEV_CONF_GET(in_dev, NOPOLICY), false, do_cache);
1983         if (!rth)
1984                 goto e_nobufs;
1985
1986         rth->dst.output= ip_rt_bug;
1987 #ifdef CONFIG_IP_ROUTE_CLASSID
1988         rth->dst.tclassid = itag;
1989 #endif
1990         rth->rt_is_input = 1;
1991         if (res.table)
1992                 rth->rt_table_id = res.table->tb_id;
1993
1994         RT_CACHE_STAT_INC(in_slow_tot);
1995         if (res.type == RTN_UNREACHABLE) {
1996                 rth->dst.input= ip_error;
1997                 rth->dst.error= -err;
1998                 rth->rt_flags   &= ~RTCF_LOCAL;
1999         }
2000
2001         if (do_cache) {
2002                 struct fib_nh *nh = &FIB_RES_NH(res);
2003
2004                 rth->dst.lwtstate = lwtstate_get(nh->nh_lwtstate);
2005                 if (lwtunnel_input_redirect(rth->dst.lwtstate)) {
2006                         WARN_ON(rth->dst.input == lwtunnel_input);
2007                         rth->dst.lwtstate->orig_input = rth->dst.input;
2008                         rth->dst.input = lwtunnel_input;
2009                 }
2010
2011                 if (unlikely(!rt_cache_route(nh, rth))) {
2012                         rth->dst.flags |= DST_NOCACHE;
2013                         rt_add_uncached_list(rth);
2014                 }
2015         }
2016         skb_dst_set(skb, &rth->dst);
2017         err = 0;
2018         goto out;
2019
2020 no_route:
2021         RT_CACHE_STAT_INC(in_no_route);
2022         res.type = RTN_UNREACHABLE;
2023         res.fi = NULL;
2024         res.table = NULL;
2025         goto local_input;
2026
2027         /*
2028          *      Do not cache martian addresses: they should be logged (RFC1812)
2029          */
2030 martian_destination:
2031         RT_CACHE_STAT_INC(in_martian_dst);
2032 #ifdef CONFIG_IP_ROUTE_VERBOSE
2033         if (IN_DEV_LOG_MARTIANS(in_dev))
2034                 net_warn_ratelimited("martian destination %pI4 from %pI4, dev %s\n",
2035                                      &daddr, &saddr, dev->name);
2036 #endif
2037
2038 e_inval:
2039         err = -EINVAL;
2040         goto out;
2041
2042 e_nobufs:
2043         err = -ENOBUFS;
2044         goto out;
2045
2046 martian_source:
2047         ip_handle_martian_source(dev, in_dev, skb, daddr, saddr);
2048         goto out;
2049 }
2050
2051 int ip_route_input_noref(struct sk_buff *skb, __be32 daddr, __be32 saddr,
2052                          u8 tos, struct net_device *dev)
2053 {
2054         int res;
2055
2056         tos &= IPTOS_RT_MASK;
2057         rcu_read_lock();
2058
2059         /* Multicast recognition logic is moved from route cache to here.
2060            The problem was that too many Ethernet cards have broken/missing
2061            hardware multicast filters :-( As result the host on multicasting
2062            network acquires a lot of useless route cache entries, sort of
2063            SDR messages from all the world. Now we try to get rid of them.
2064            Really, provided software IP multicast filter is organized
2065            reasonably (at least, hashed), it does not result in a slowdown
2066            comparing with route cache reject entries.
2067            Note, that multicast routers are not affected, because
2068            route cache entry is created eventually.
2069          */
2070         if (ipv4_is_multicast(daddr)) {
2071                 struct in_device *in_dev = __in_dev_get_rcu(dev);
2072                 int our = 0;
2073
2074                 if (in_dev)
2075                         our = ip_check_mc_rcu(in_dev, daddr, saddr,
2076                                               ip_hdr(skb)->protocol);
2077
2078                 /* check l3 master if no match yet */
2079                 if ((!in_dev || !our) && netif_is_l3_slave(dev)) {
2080                         struct in_device *l3_in_dev;
2081
2082                         l3_in_dev = __in_dev_get_rcu(skb->dev);
2083                         if (l3_in_dev)
2084                                 our = ip_check_mc_rcu(l3_in_dev, daddr, saddr,
2085                                                       ip_hdr(skb)->protocol);
2086                 }
2087
2088                 res = -EINVAL;
2089                 if (our
2090 #ifdef CONFIG_IP_MROUTE
2091                         ||
2092                     (!ipv4_is_local_multicast(daddr) &&
2093                      IN_DEV_MFORWARD(in_dev))
2094 #endif
2095                    ) {
2096                         res = ip_route_input_mc(skb, daddr, saddr,
2097                                                 tos, dev, our);
2098                 }
2099                 rcu_read_unlock();
2100                 return res;
2101         }
2102         res = ip_route_input_slow(skb, daddr, saddr, tos, dev);
2103         rcu_read_unlock();
2104         return res;
2105 }
2106 EXPORT_SYMBOL(ip_route_input_noref);
2107
2108 /* called with rcu_read_lock() */
2109 static struct rtable *__mkroute_output(const struct fib_result *res,
2110                                        const struct flowi4 *fl4, int orig_oif,
2111                                        struct net_device *dev_out,
2112                                        unsigned int flags)
2113 {
2114         struct fib_info *fi = res->fi;
2115         struct fib_nh_exception *fnhe;
2116         struct in_device *in_dev;
2117         u16 type = res->type;
2118         struct rtable *rth;
2119         bool do_cache;
2120
2121         in_dev = __in_dev_get_rcu(dev_out);
2122         if (!in_dev)
2123                 return ERR_PTR(-EINVAL);
2124
2125         if (likely(!IN_DEV_ROUTE_LOCALNET(in_dev)))
2126                 if (ipv4_is_loopback(fl4->saddr) &&
2127                     !(dev_out->flags & IFF_LOOPBACK) &&
2128                     !netif_is_l3_master(dev_out))
2129                         return ERR_PTR(-EINVAL);
2130
2131         if (ipv4_is_lbcast(fl4->daddr))
2132                 type = RTN_BROADCAST;
2133         else if (ipv4_is_multicast(fl4->daddr))
2134                 type = RTN_MULTICAST;
2135         else if (ipv4_is_zeronet(fl4->daddr))
2136                 return ERR_PTR(-EINVAL);
2137
2138         if (dev_out->flags & IFF_LOOPBACK)
2139                 flags |= RTCF_LOCAL;
2140
2141         do_cache = true;
2142         if (type == RTN_BROADCAST) {
2143                 flags |= RTCF_BROADCAST | RTCF_LOCAL;
2144                 fi = NULL;
2145         } else if (type == RTN_MULTICAST) {
2146                 flags |= RTCF_MULTICAST | RTCF_LOCAL;
2147                 if (!ip_check_mc_rcu(in_dev, fl4->daddr, fl4->saddr,
2148                                      fl4->flowi4_proto))
2149                         flags &= ~RTCF_LOCAL;
2150                 else
2151                         do_cache = false;
2152                 /* If multicast route do not exist use
2153                  * default one, but do not gateway in this case.
2154                  * Yes, it is hack.
2155                  */
2156                 if (fi && res->prefixlen < 4)
2157                         fi = NULL;
2158         } else if ((type == RTN_LOCAL) && (orig_oif != 0) &&
2159                    (orig_oif != dev_out->ifindex)) {
2160                 /* For local routes that require a particular output interface
2161                  * we do not want to cache the result.  Caching the result
2162                  * causes incorrect behaviour when there are multiple source
2163                  * addresses on the interface, the end result being that if the
2164                  * intended recipient is waiting on that interface for the
2165                  * packet he won't receive it because it will be delivered on
2166                  * the loopback interface and the IP_PKTINFO ipi_ifindex will
2167                  * be set to the loopback interface as well.
2168                  */
2169                 fi = NULL;
2170         }
2171
2172         fnhe = NULL;
2173         do_cache &= fi != NULL;
2174         if (do_cache) {
2175                 struct rtable __rcu **prth;
2176                 struct fib_nh *nh = &FIB_RES_NH(*res);
2177
2178                 fnhe = find_exception(nh, fl4->daddr);
2179                 if (fnhe) {
2180                         prth = &fnhe->fnhe_rth_output;
2181                         rth = rcu_dereference(*prth);
2182                         if (rth && rth->dst.expires &&
2183                             time_after(jiffies, rth->dst.expires)) {
2184                                 ip_del_fnhe(nh, fl4->daddr);
2185                                 fnhe = NULL;
2186                         } else {
2187                                 goto rt_cache;
2188                         }
2189                 }
2190
2191                 if (unlikely(fl4->flowi4_flags &
2192                              FLOWI_FLAG_KNOWN_NH &&
2193                              !(nh->nh_gw &&
2194                                nh->nh_scope == RT_SCOPE_LINK))) {
2195                         do_cache = false;
2196                         goto add;
2197                 }
2198                 prth = raw_cpu_ptr(nh->nh_pcpu_rth_output);
2199                 rth = rcu_dereference(*prth);
2200
2201 rt_cache:
2202                 if (rt_cache_valid(rth)) {
2203                         dst_hold(&rth->dst);
2204                         return rth;
2205                 }
2206         }
2207
2208 add:
2209         rth = rt_dst_alloc(dev_out, flags, type,
2210                            IN_DEV_CONF_GET(in_dev, NOPOLICY),
2211                            IN_DEV_CONF_GET(in_dev, NOXFRM),
2212                            do_cache);
2213         if (!rth)
2214                 return ERR_PTR(-ENOBUFS);
2215
2216         rth->rt_iif     = orig_oif ? : 0;
2217         if (res->table)
2218                 rth->rt_table_id = res->table->tb_id;
2219
2220         RT_CACHE_STAT_INC(out_slow_tot);
2221
2222         if (flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
2223                 if (flags & RTCF_LOCAL &&
2224                     !(dev_out->flags & IFF_LOOPBACK)) {
2225                         rth->dst.output = ip_mc_output;
2226                         RT_CACHE_STAT_INC(out_slow_mc);
2227                 }
2228 #ifdef CONFIG_IP_MROUTE
2229                 if (type == RTN_MULTICAST) {
2230                         if (IN_DEV_MFORWARD(in_dev) &&
2231                             !ipv4_is_local_multicast(fl4->daddr)) {
2232                                 rth->dst.input = ip_mr_input;
2233                                 rth->dst.output = ip_mc_output;
2234                         }
2235                 }
2236 #endif
2237         }
2238
2239         rt_set_nexthop(rth, fl4->daddr, res, fnhe, fi, type, 0);
2240         set_lwt_redirect(rth);
2241
2242         return rth;
2243 }
2244
2245 /*
2246  * Major route resolver routine.
2247  */
2248
2249 struct rtable *__ip_route_output_key_hash(struct net *net, struct flowi4 *fl4,
2250                                           const struct sk_buff *skb)
2251 {
2252         struct net_device *dev_out = NULL;
2253         __u8 tos = RT_FL_TOS(fl4);
2254         unsigned int flags = 0;
2255         struct fib_result res;
2256         struct rtable *rth;
2257         int orig_oif;
2258         int err = -ENETUNREACH;
2259
2260         res.tclassid    = 0;
2261         res.fi          = NULL;
2262         res.table       = NULL;
2263
2264         orig_oif = fl4->flowi4_oif;
2265
2266         fl4->flowi4_iif = LOOPBACK_IFINDEX;
2267         fl4->flowi4_tos = tos & IPTOS_RT_MASK;
2268         fl4->flowi4_scope = ((tos & RTO_ONLINK) ?
2269                          RT_SCOPE_LINK : RT_SCOPE_UNIVERSE);
2270
2271         rcu_read_lock();
2272         if (fl4->saddr) {
2273                 rth = ERR_PTR(-EINVAL);
2274                 if (ipv4_is_multicast(fl4->saddr) ||
2275                     ipv4_is_lbcast(fl4->saddr) ||
2276                     ipv4_is_zeronet(fl4->saddr))
2277                         goto out;
2278
2279                 /* I removed check for oif == dev_out->oif here.
2280                    It was wrong for two reasons:
2281                    1. ip_dev_find(net, saddr) can return wrong iface, if saddr
2282                       is assigned to multiple interfaces.
2283                    2. Moreover, we are allowed to send packets with saddr
2284                       of another iface. --ANK
2285                  */
2286
2287                 if (fl4->flowi4_oif == 0 &&
2288                     (ipv4_is_multicast(fl4->daddr) ||
2289                      ipv4_is_lbcast(fl4->daddr))) {
2290                         /* It is equivalent to inet_addr_type(saddr) == RTN_LOCAL */
2291                         dev_out = __ip_dev_find(net, fl4->saddr, false);
2292                         if (!dev_out)
2293                                 goto out;
2294
2295                         /* Special hack: user can direct multicasts
2296                            and limited broadcast via necessary interface
2297                            without fiddling with IP_MULTICAST_IF or IP_PKTINFO.
2298                            This hack is not just for fun, it allows
2299                            vic,vat and friends to work.
2300                            They bind socket to loopback, set ttl to zero
2301                            and expect that it will work.
2302                            From the viewpoint of routing cache they are broken,
2303                            because we are not allowed to build multicast path
2304                            with loopback source addr (look, routing cache
2305                            cannot know, that ttl is zero, so that packet
2306                            will not leave this host and route is valid).
2307                            Luckily, this hack is good workaround.
2308                          */
2309
2310                         fl4->flowi4_oif = dev_out->ifindex;
2311                         goto make_route;
2312                 }
2313
2314                 if (!(fl4->flowi4_flags & FLOWI_FLAG_ANYSRC)) {
2315                         /* It is equivalent to inet_addr_type(saddr) == RTN_LOCAL */
2316                         if (!__ip_dev_find(net, fl4->saddr, false))
2317                                 goto out;
2318                 }
2319         }
2320
2321
2322         if (fl4->flowi4_oif) {
2323                 dev_out = dev_get_by_index_rcu(net, fl4->flowi4_oif);
2324                 rth = ERR_PTR(-ENODEV);
2325                 if (!dev_out)
2326                         goto out;
2327
2328                 /* RACE: Check return value of inet_select_addr instead. */
2329                 if (!(dev_out->flags & IFF_UP) || !__in_dev_get_rcu(dev_out)) {
2330                         rth = ERR_PTR(-ENETUNREACH);
2331                         goto out;
2332                 }
2333                 if (ipv4_is_local_multicast(fl4->daddr) ||
2334                     ipv4_is_lbcast(fl4->daddr) ||
2335                     fl4->flowi4_proto == IPPROTO_IGMP) {
2336                         if (!fl4->saddr)
2337                                 fl4->saddr = inet_select_addr(dev_out, 0,
2338                                                               RT_SCOPE_LINK);
2339                         goto make_route;
2340                 }
2341                 if (!fl4->saddr) {
2342                         if (ipv4_is_multicast(fl4->daddr))
2343                                 fl4->saddr = inet_select_addr(dev_out, 0,
2344                                                               fl4->flowi4_scope);
2345                         else if (!fl4->daddr)
2346                                 fl4->saddr = inet_select_addr(dev_out, 0,
2347                                                               RT_SCOPE_HOST);
2348                 }
2349         }
2350
2351         if (!fl4->daddr) {
2352                 fl4->daddr = fl4->saddr;
2353                 if (!fl4->daddr)
2354                         fl4->daddr = fl4->saddr = htonl(INADDR_LOOPBACK);
2355                 dev_out = net->loopback_dev;
2356                 fl4->flowi4_oif = LOOPBACK_IFINDEX;
2357                 res.type = RTN_LOCAL;
2358                 flags |= RTCF_LOCAL;
2359                 goto make_route;
2360         }
2361
2362         err = fib_lookup(net, fl4, &res, 0);
2363         if (err) {
2364                 res.fi = NULL;
2365                 res.table = NULL;
2366                 if (fl4->flowi4_oif &&
2367                     (ipv4_is_multicast(fl4->daddr) ||
2368                     !netif_index_is_l3_master(net, fl4->flowi4_oif))) {
2369                         /* Apparently, routing tables are wrong. Assume,
2370                            that the destination is on link.
2371
2372                            WHY? DW.
2373                            Because we are allowed to send to iface
2374                            even if it has NO routes and NO assigned
2375                            addresses. When oif is specified, routing
2376                            tables are looked up with only one purpose:
2377                            to catch if destination is gatewayed, rather than
2378                            direct. Moreover, if MSG_DONTROUTE is set,
2379                            we send packet, ignoring both routing tables
2380                            and ifaddr state. --ANK
2381
2382
2383                            We could make it even if oif is unknown,
2384                            likely IPv6, but we do not.
2385                          */
2386
2387                         if (fl4->saddr == 0)
2388                                 fl4->saddr = inet_select_addr(dev_out, 0,
2389                                                               RT_SCOPE_LINK);
2390                         res.type = RTN_UNICAST;
2391                         goto make_route;
2392                 }
2393                 rth = ERR_PTR(err);
2394                 goto out;
2395         }
2396
2397         if (res.type == RTN_LOCAL) {
2398                 if (!fl4->saddr) {
2399                         if (res.fi->fib_prefsrc)
2400                                 fl4->saddr = res.fi->fib_prefsrc;
2401                         else
2402                                 fl4->saddr = fl4->daddr;
2403                 }
2404
2405                 /* L3 master device is the loopback for that domain */
2406                 dev_out = l3mdev_master_dev_rcu(FIB_RES_DEV(res)) ? :
2407                         net->loopback_dev;
2408                 fl4->flowi4_oif = dev_out->ifindex;
2409                 flags |= RTCF_LOCAL;
2410                 goto make_route;
2411         }
2412
2413         fib_select_path(net, &res, fl4, skb);
2414
2415         dev_out = FIB_RES_DEV(res);
2416         fl4->flowi4_oif = dev_out->ifindex;
2417
2418
2419 make_route:
2420         rth = __mkroute_output(&res, fl4, orig_oif, dev_out, flags);
2421
2422 out:
2423         rcu_read_unlock();
2424         return rth;
2425 }
2426 EXPORT_SYMBOL_GPL(__ip_route_output_key_hash);
2427
2428 static struct dst_entry *ipv4_blackhole_dst_check(struct dst_entry *dst, u32 cookie)
2429 {
2430         return NULL;
2431 }
2432
2433 static unsigned int ipv4_blackhole_mtu(const struct dst_entry *dst)
2434 {
2435         unsigned int mtu = dst_metric_raw(dst, RTAX_MTU);
2436
2437         return mtu ? : dst->dev->mtu;
2438 }
2439
2440 static void ipv4_rt_blackhole_update_pmtu(struct dst_entry *dst, struct sock *sk,
2441                                           struct sk_buff *skb, u32 mtu)
2442 {
2443 }
2444
2445 static void ipv4_rt_blackhole_redirect(struct dst_entry *dst, struct sock *sk,
2446                                        struct sk_buff *skb)
2447 {
2448 }
2449
2450 static u32 *ipv4_rt_blackhole_cow_metrics(struct dst_entry *dst,
2451                                           unsigned long old)
2452 {
2453         return NULL;
2454 }
2455
2456 static struct dst_ops ipv4_dst_blackhole_ops = {
2457         .family                 =       AF_INET,
2458         .check                  =       ipv4_blackhole_dst_check,
2459         .mtu                    =       ipv4_blackhole_mtu,
2460         .default_advmss         =       ipv4_default_advmss,
2461         .update_pmtu            =       ipv4_rt_blackhole_update_pmtu,
2462         .redirect               =       ipv4_rt_blackhole_redirect,
2463         .cow_metrics            =       ipv4_rt_blackhole_cow_metrics,
2464         .neigh_lookup           =       ipv4_neigh_lookup,
2465 };
2466
2467 struct dst_entry *ipv4_blackhole_route(struct net *net, struct dst_entry *dst_orig)
2468 {
2469         struct rtable *ort = (struct rtable *) dst_orig;
2470         struct rtable *rt;
2471
2472         rt = dst_alloc(&ipv4_dst_blackhole_ops, NULL, 1, DST_OBSOLETE_NONE, 0);
2473         if (rt) {
2474                 struct dst_entry *new = &rt->dst;
2475
2476                 new->__use = 1;
2477                 new->input = dst_discard;
2478                 new->output = dst_discard_out;
2479
2480                 new->dev = ort->dst.dev;
2481                 if (new->dev)
2482                         dev_hold(new->dev);
2483
2484                 rt->rt_is_input = ort->rt_is_input;
2485                 rt->rt_iif = ort->rt_iif;
2486                 rt->rt_pmtu = ort->rt_pmtu;
2487
2488                 rt->rt_genid = rt_genid_ipv4(net);
2489                 rt->rt_flags = ort->rt_flags;
2490                 rt->rt_type = ort->rt_type;
2491                 rt->rt_gateway = ort->rt_gateway;
2492                 rt->rt_uses_gateway = ort->rt_uses_gateway;
2493
2494                 INIT_LIST_HEAD(&rt->rt_uncached);
2495                 dst_free(new);
2496         }
2497
2498         dst_release(dst_orig);
2499
2500         return rt ? &rt->dst : ERR_PTR(-ENOMEM);
2501 }
2502
2503 struct rtable *ip_route_output_flow(struct net *net, struct flowi4 *flp4,
2504                                     const struct sock *sk)
2505 {
2506         struct rtable *rt = __ip_route_output_key(net, flp4);
2507
2508         if (IS_ERR(rt))
2509                 return rt;
2510
2511         if (flp4->flowi4_proto)
2512                 rt = (struct rtable *)xfrm_lookup_route(net, &rt->dst,
2513                                                         flowi4_to_flowi(flp4),
2514                                                         sk, 0);
2515
2516         return rt;
2517 }
2518 EXPORT_SYMBOL_GPL(ip_route_output_flow);
2519
2520 static int rt_fill_info(struct net *net,  __be32 dst, __be32 src, u32 table_id,
2521                         struct flowi4 *fl4, struct sk_buff *skb, u32 portid,
2522                         u32 seq, int event)
2523 {
2524         struct rtable *rt = skb_rtable(skb);
2525         struct rtmsg *r;
2526         struct nlmsghdr *nlh;
2527         unsigned long expires = 0;
2528         u32 error;
2529         u32 metrics[RTAX_MAX];
2530
2531         nlh = nlmsg_put(skb, portid, seq, event, sizeof(*r), 0);
2532         if (!nlh)
2533                 return -EMSGSIZE;
2534
2535         r = nlmsg_data(nlh);
2536         r->rtm_family    = AF_INET;
2537         r->rtm_dst_len  = 32;
2538         r->rtm_src_len  = 0;
2539         r->rtm_tos      = fl4->flowi4_tos;
2540         r->rtm_table    = table_id < 256 ? table_id : RT_TABLE_COMPAT;
2541         if (nla_put_u32(skb, RTA_TABLE, table_id))
2542                 goto nla_put_failure;
2543         r->rtm_type     = rt->rt_type;
2544         r->rtm_scope    = RT_SCOPE_UNIVERSE;
2545         r->rtm_protocol = RTPROT_UNSPEC;
2546         r->rtm_flags    = (rt->rt_flags & ~0xFFFF) | RTM_F_CLONED;
2547         if (rt->rt_flags & RTCF_NOTIFY)
2548                 r->rtm_flags |= RTM_F_NOTIFY;
2549         if (IPCB(skb)->flags & IPSKB_DOREDIRECT)
2550                 r->rtm_flags |= RTCF_DOREDIRECT;
2551
2552         if (nla_put_in_addr(skb, RTA_DST, dst))
2553                 goto nla_put_failure;
2554         if (src) {
2555                 r->rtm_src_len = 32;
2556                 if (nla_put_in_addr(skb, RTA_SRC, src))
2557                         goto nla_put_failure;
2558         }
2559         if (rt->dst.dev &&
2560             nla_put_u32(skb, RTA_OIF, rt->dst.dev->ifindex))
2561                 goto nla_put_failure;
2562 #ifdef CONFIG_IP_ROUTE_CLASSID
2563         if (rt->dst.tclassid &&
2564             nla_put_u32(skb, RTA_FLOW, rt->dst.tclassid))
2565                 goto nla_put_failure;
2566 #endif
2567         if (!rt_is_input_route(rt) &&
2568             fl4->saddr != src) {
2569                 if (nla_put_in_addr(skb, RTA_PREFSRC, fl4->saddr))
2570                         goto nla_put_failure;
2571         }
2572         if (rt->rt_uses_gateway &&
2573             nla_put_in_addr(skb, RTA_GATEWAY, rt->rt_gateway))
2574                 goto nla_put_failure;
2575
2576         expires = rt->dst.expires;
2577         if (expires) {
2578                 unsigned long now = jiffies;
2579
2580                 if (time_before(now, expires))
2581                         expires -= now;
2582                 else
2583                         expires = 0;
2584         }
2585
2586         memcpy(metrics, dst_metrics_ptr(&rt->dst), sizeof(metrics));
2587         if (rt->rt_pmtu && expires)
2588                 metrics[RTAX_MTU - 1] = rt->rt_pmtu;
2589         if (rtnetlink_put_metrics(skb, metrics) < 0)
2590                 goto nla_put_failure;
2591
2592         if (fl4->flowi4_mark &&
2593             nla_put_u32(skb, RTA_MARK, fl4->flowi4_mark))
2594                 goto nla_put_failure;
2595
2596         if (!uid_eq(fl4->flowi4_uid, INVALID_UID) &&
2597             nla_put_u32(skb, RTA_UID,
2598                         from_kuid_munged(current_user_ns(), fl4->flowi4_uid)))
2599                 goto nla_put_failure;
2600
2601         error = rt->dst.error;
2602
2603         if (rt_is_input_route(rt)) {
2604 #ifdef CONFIG_IP_MROUTE
2605                 if (ipv4_is_multicast(dst) && !ipv4_is_local_multicast(dst) &&
2606                     IPV4_DEVCONF_ALL(net, MC_FORWARDING)) {
2607                         int err = ipmr_get_route(net, skb,
2608                                                  fl4->saddr, fl4->daddr,
2609                                                  r, portid);
2610
2611                         if (err <= 0) {
2612                                 if (err == 0)
2613                                         return 0;
2614                                 goto nla_put_failure;
2615                         }
2616                 } else
2617 #endif
2618                         if (nla_put_u32(skb, RTA_IIF, skb->dev->ifindex))
2619                                 goto nla_put_failure;
2620         }
2621
2622         if (rtnl_put_cacheinfo(skb, &rt->dst, 0, expires, error) < 0)
2623                 goto nla_put_failure;
2624
2625         nlmsg_end(skb, nlh);
2626         return 0;
2627
2628 nla_put_failure:
2629         nlmsg_cancel(skb, nlh);
2630         return -EMSGSIZE;
2631 }
2632
2633 static int inet_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh,
2634                              struct netlink_ext_ack *extack)
2635 {
2636         struct net *net = sock_net(in_skb->sk);
2637         struct rtmsg *rtm;
2638         struct nlattr *tb[RTA_MAX+1];
2639         struct rtable *rt = NULL;
2640         struct flowi4 fl4;
2641         __be32 dst = 0;
2642         __be32 src = 0;
2643         u32 iif;
2644         int err;
2645         int mark;
2646         struct sk_buff *skb;
2647         u32 table_id = RT_TABLE_MAIN;
2648         kuid_t uid;
2649
2650         err = nlmsg_parse(nlh, sizeof(*rtm), tb, RTA_MAX, rtm_ipv4_policy,
2651                           extack);
2652         if (err < 0)
2653                 goto errout;
2654
2655         rtm = nlmsg_data(nlh);
2656
2657         skb = alloc_skb(NLMSG_GOODSIZE, GFP_KERNEL);
2658         if (!skb) {
2659                 err = -ENOBUFS;
2660                 goto errout;
2661         }
2662
2663         /* Reserve room for dummy headers, this skb can pass
2664            through good chunk of routing engine.
2665          */
2666         skb_reset_mac_header(skb);
2667         skb_reset_network_header(skb);
2668
2669         src = tb[RTA_SRC] ? nla_get_in_addr(tb[RTA_SRC]) : 0;
2670         dst = tb[RTA_DST] ? nla_get_in_addr(tb[RTA_DST]) : 0;
2671         iif = tb[RTA_IIF] ? nla_get_u32(tb[RTA_IIF]) : 0;
2672         mark = tb[RTA_MARK] ? nla_get_u32(tb[RTA_MARK]) : 0;
2673         if (tb[RTA_UID])
2674                 uid = make_kuid(current_user_ns(), nla_get_u32(tb[RTA_UID]));
2675         else
2676                 uid = (iif ? INVALID_UID : current_uid());
2677
2678         /* Bugfix: need to give ip_route_input enough of an IP header to
2679          * not gag.
2680          */
2681         ip_hdr(skb)->protocol = IPPROTO_UDP;
2682         ip_hdr(skb)->saddr = src;
2683         ip_hdr(skb)->daddr = dst;
2684
2685         skb_reserve(skb, MAX_HEADER + sizeof(struct iphdr));
2686
2687         memset(&fl4, 0, sizeof(fl4));
2688         fl4.daddr = dst;
2689         fl4.saddr = src;
2690         fl4.flowi4_tos = rtm->rtm_tos;
2691         fl4.flowi4_oif = tb[RTA_OIF] ? nla_get_u32(tb[RTA_OIF]) : 0;
2692         fl4.flowi4_mark = mark;
2693         fl4.flowi4_uid = uid;
2694
2695         if (iif) {
2696                 struct net_device *dev;
2697
2698                 dev = __dev_get_by_index(net, iif);
2699                 if (!dev) {
2700                         err = -ENODEV;
2701                         goto errout_free;
2702                 }
2703
2704                 skb->protocol   = htons(ETH_P_IP);
2705                 skb->dev        = dev;
2706                 skb->mark       = mark;
2707                 err = ip_route_input(skb, dst, src, rtm->rtm_tos, dev);
2708
2709                 rt = skb_rtable(skb);
2710                 if (err == 0 && rt->dst.error)
2711                         err = -rt->dst.error;
2712         } else {
2713                 rt = ip_route_output_key(net, &fl4);
2714
2715                 err = 0;
2716                 if (IS_ERR(rt))
2717                         err = PTR_ERR(rt);
2718         }
2719
2720         if (err)
2721                 goto errout_free;
2722
2723         skb_dst_set(skb, &rt->dst);
2724         if (rtm->rtm_flags & RTM_F_NOTIFY)
2725                 rt->rt_flags |= RTCF_NOTIFY;
2726
2727         if (rtm->rtm_flags & RTM_F_LOOKUP_TABLE)
2728                 table_id = rt->rt_table_id;
2729
2730         err = rt_fill_info(net, dst, src, table_id, &fl4, skb,
2731                            NETLINK_CB(in_skb).portid, nlh->nlmsg_seq,
2732                            RTM_NEWROUTE);
2733         if (err < 0)
2734                 goto errout_free;
2735
2736         err = rtnl_unicast(skb, net, NETLINK_CB(in_skb).portid);
2737 errout:
2738         return err;
2739
2740 errout_free:
2741         kfree_skb(skb);
2742         goto errout;
2743 }
2744
2745 void ip_rt_multicast_event(struct in_device *in_dev)
2746 {
2747         rt_cache_flush(dev_net(in_dev->dev));
2748 }
2749
2750 #ifdef CONFIG_SYSCTL
2751 static int ip_rt_gc_interval __read_mostly  = 60 * HZ;
2752 static int ip_rt_gc_min_interval __read_mostly  = HZ / 2;
2753 static int ip_rt_gc_elasticity __read_mostly    = 8;
2754
2755 static int ipv4_sysctl_rtcache_flush(struct ctl_table *__ctl, int write,
2756                                         void __user *buffer,
2757                                         size_t *lenp, loff_t *ppos)
2758 {
2759         struct net *net = (struct net *)__ctl->extra1;
2760
2761         if (write) {
2762                 rt_cache_flush(net);
2763                 fnhe_genid_bump(net);
2764                 return 0;
2765         }
2766
2767         return -EINVAL;
2768 }
2769
2770 static struct ctl_table ipv4_route_table[] = {
2771         {
2772                 .procname       = "gc_thresh",
2773                 .data           = &ipv4_dst_ops.gc_thresh,
2774                 .maxlen         = sizeof(int),
2775                 .mode           = 0644,
2776                 .proc_handler   = proc_dointvec,
2777         },
2778         {
2779                 .procname       = "max_size",
2780                 .data           = &ip_rt_max_size,
2781                 .maxlen         = sizeof(int),
2782                 .mode           = 0644,
2783                 .proc_handler   = proc_dointvec,
2784         },
2785         {
2786                 /*  Deprecated. Use gc_min_interval_ms */
2787
2788                 .procname       = "gc_min_interval",
2789                 .data           = &ip_rt_gc_min_interval,
2790                 .maxlen         = sizeof(int),
2791                 .mode           = 0644,
2792                 .proc_handler   = proc_dointvec_jiffies,
2793         },
2794         {
2795                 .procname       = "gc_min_interval_ms",
2796                 .data           = &ip_rt_gc_min_interval,
2797                 .maxlen         = sizeof(int),
2798                 .mode           = 0644,
2799                 .proc_handler   = proc_dointvec_ms_jiffies,
2800         },
2801         {
2802                 .procname       = "gc_timeout",
2803                 .data           = &ip_rt_gc_timeout,
2804                 .maxlen         = sizeof(int),
2805                 .mode           = 0644,
2806                 .proc_handler   = proc_dointvec_jiffies,
2807         },
2808         {
2809                 .procname       = "gc_interval",
2810                 .data           = &ip_rt_gc_interval,
2811                 .maxlen         = sizeof(int),
2812                 .mode           = 0644,
2813                 .proc_handler   = proc_dointvec_jiffies,
2814         },
2815         {
2816                 .procname       = "redirect_load",
2817                 .data           = &ip_rt_redirect_load,
2818                 .maxlen         = sizeof(int),
2819                 .mode           = 0644,
2820                 .proc_handler   = proc_dointvec,
2821         },
2822         {
2823                 .procname       = "redirect_number",
2824                 .data           = &ip_rt_redirect_number,
2825                 .maxlen         = sizeof(int),
2826                 .mode           = 0644,
2827                 .proc_handler   = proc_dointvec,
2828         },
2829         {
2830                 .procname       = "redirect_silence",
2831                 .data           = &ip_rt_redirect_silence,
2832                 .maxlen         = sizeof(int),
2833                 .mode           = 0644,
2834                 .proc_handler   = proc_dointvec,
2835         },
2836         {
2837                 .procname       = "error_cost",
2838                 .data           = &ip_rt_error_cost,
2839                 .maxlen         = sizeof(int),
2840                 .mode           = 0644,
2841                 .proc_handler   = proc_dointvec,
2842         },
2843         {
2844                 .procname       = "error_burst",
2845                 .data           = &ip_rt_error_burst,
2846                 .maxlen         = sizeof(int),
2847                 .mode           = 0644,
2848                 .proc_handler   = proc_dointvec,
2849         },
2850         {
2851                 .procname       = "gc_elasticity",
2852                 .data           = &ip_rt_gc_elasticity,
2853                 .maxlen         = sizeof(int),
2854                 .mode           = 0644,
2855                 .proc_handler   = proc_dointvec,
2856         },
2857         {
2858                 .procname       = "mtu_expires",
2859                 .data           = &ip_rt_mtu_expires,
2860                 .maxlen         = sizeof(int),
2861                 .mode           = 0644,
2862                 .proc_handler   = proc_dointvec_jiffies,
2863         },
2864         {
2865                 .procname       = "min_pmtu",
2866                 .data           = &ip_rt_min_pmtu,
2867                 .maxlen         = sizeof(int),
2868                 .mode           = 0644,
2869                 .proc_handler   = proc_dointvec,
2870         },
2871         {
2872                 .procname       = "min_adv_mss",
2873                 .data           = &ip_rt_min_advmss,
2874                 .maxlen         = sizeof(int),
2875                 .mode           = 0644,
2876                 .proc_handler   = proc_dointvec,
2877         },
2878         { }
2879 };
2880
2881 static struct ctl_table ipv4_route_flush_table[] = {
2882         {
2883                 .procname       = "flush",
2884                 .maxlen         = sizeof(int),
2885                 .mode           = 0200,
2886                 .proc_handler   = ipv4_sysctl_rtcache_flush,
2887         },
2888         { },
2889 };
2890
2891 static __net_init int sysctl_route_net_init(struct net *net)
2892 {
2893         struct ctl_table *tbl;
2894
2895         tbl = ipv4_route_flush_table;
2896         if (!net_eq(net, &init_net)) {
2897                 tbl = kmemdup(tbl, sizeof(ipv4_route_flush_table), GFP_KERNEL);
2898                 if (!tbl)
2899                         goto err_dup;
2900
2901                 /* Don't export sysctls to unprivileged users */
2902                 if (net->user_ns != &init_user_ns)
2903                         tbl[0].procname = NULL;
2904         }
2905         tbl[0].extra1 = net;
2906
2907         net->ipv4.route_hdr = register_net_sysctl(net, "net/ipv4/route", tbl);
2908         if (!net->ipv4.route_hdr)
2909                 goto err_reg;
2910         return 0;
2911
2912 err_reg:
2913         if (tbl != ipv4_route_flush_table)
2914                 kfree(tbl);
2915 err_dup:
2916         return -ENOMEM;
2917 }
2918
2919 static __net_exit void sysctl_route_net_exit(struct net *net)
2920 {
2921         struct ctl_table *tbl;
2922
2923         tbl = net->ipv4.route_hdr->ctl_table_arg;
2924         unregister_net_sysctl_table(net->ipv4.route_hdr);
2925         BUG_ON(tbl == ipv4_route_flush_table);
2926         kfree(tbl);
2927 }
2928
2929 static __net_initdata struct pernet_operations sysctl_route_ops = {
2930         .init = sysctl_route_net_init,
2931         .exit = sysctl_route_net_exit,
2932 };
2933 #endif
2934
2935 static __net_init int rt_genid_init(struct net *net)
2936 {
2937         atomic_set(&net->ipv4.rt_genid, 0);
2938         atomic_set(&net->fnhe_genid, 0);
2939         get_random_bytes(&net->ipv4.dev_addr_genid,
2940                          sizeof(net->ipv4.dev_addr_genid));
2941         return 0;
2942 }
2943
2944 static __net_initdata struct pernet_operations rt_genid_ops = {
2945         .init = rt_genid_init,
2946 };
2947
2948 static int __net_init ipv4_inetpeer_init(struct net *net)
2949 {
2950         struct inet_peer_base *bp = kmalloc(sizeof(*bp), GFP_KERNEL);
2951
2952         if (!bp)
2953                 return -ENOMEM;
2954         inet_peer_base_init(bp);
2955         net->ipv4.peers = bp;
2956         return 0;
2957 }
2958
2959 static void __net_exit ipv4_inetpeer_exit(struct net *net)
2960 {
2961         struct inet_peer_base *bp = net->ipv4.peers;
2962
2963         net->ipv4.peers = NULL;
2964         inetpeer_invalidate_tree(bp);
2965         kfree(bp);
2966 }
2967
2968 static __net_initdata struct pernet_operations ipv4_inetpeer_ops = {
2969         .init   =       ipv4_inetpeer_init,
2970         .exit   =       ipv4_inetpeer_exit,
2971 };
2972
2973 #ifdef CONFIG_IP_ROUTE_CLASSID
2974 struct ip_rt_acct __percpu *ip_rt_acct __read_mostly;
2975 #endif /* CONFIG_IP_ROUTE_CLASSID */
2976
2977 int __init ip_rt_init(void)
2978 {
2979         int rc = 0;
2980         int cpu;
2981
2982         ip_idents = kmalloc(IP_IDENTS_SZ * sizeof(*ip_idents), GFP_KERNEL);
2983         if (!ip_idents)
2984                 panic("IP: failed to allocate ip_idents\n");
2985
2986         prandom_bytes(ip_idents, IP_IDENTS_SZ * sizeof(*ip_idents));
2987
2988         ip_tstamps = kcalloc(IP_IDENTS_SZ, sizeof(*ip_tstamps), GFP_KERNEL);
2989         if (!ip_tstamps)
2990                 panic("IP: failed to allocate ip_tstamps\n");
2991
2992         for_each_possible_cpu(cpu) {
2993                 struct uncached_list *ul = &per_cpu(rt_uncached_list, cpu);
2994
2995                 INIT_LIST_HEAD(&ul->head);
2996                 spin_lock_init(&ul->lock);
2997         }
2998 #ifdef CONFIG_IP_ROUTE_CLASSID
2999         ip_rt_acct = __alloc_percpu(256 * sizeof(struct ip_rt_acct), __alignof__(struct ip_rt_acct));
3000         if (!ip_rt_acct)
3001                 panic("IP: failed to allocate ip_rt_acct\n");
3002 #endif
3003
3004         ipv4_dst_ops.kmem_cachep =
3005                 kmem_cache_create("ip_dst_cache", sizeof(struct rtable), 0,
3006                                   SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
3007
3008         ipv4_dst_blackhole_ops.kmem_cachep = ipv4_dst_ops.kmem_cachep;
3009
3010         if (dst_entries_init(&ipv4_dst_ops) < 0)
3011                 panic("IP: failed to allocate ipv4_dst_ops counter\n");
3012
3013         if (dst_entries_init(&ipv4_dst_blackhole_ops) < 0)
3014                 panic("IP: failed to allocate ipv4_dst_blackhole_ops counter\n");
3015
3016         ipv4_dst_ops.gc_thresh = ~0;
3017         ip_rt_max_size = INT_MAX;
3018
3019         devinet_init();
3020         ip_fib_init();
3021
3022         if (ip_rt_proc_init())
3023                 pr_err("Unable to create route proc files\n");
3024 #ifdef CONFIG_XFRM
3025         xfrm_init();
3026         xfrm4_init();
3027 #endif
3028         rtnl_register(PF_INET, RTM_GETROUTE, inet_rtm_getroute, NULL, NULL);
3029
3030 #ifdef CONFIG_SYSCTL
3031         register_pernet_subsys(&sysctl_route_ops);
3032 #endif
3033         register_pernet_subsys(&rt_genid_ops);
3034         register_pernet_subsys(&ipv4_inetpeer_ops);
3035         return rc;
3036 }
3037
3038 #ifdef CONFIG_SYSCTL
3039 /*
3040  * We really need to sanitize the damn ipv4 init order, then all
3041  * this nonsense will go away.
3042  */
3043 void __init ip_static_sysctl_init(void)
3044 {
3045         register_net_sysctl(&init_net, "net/ipv4/route", ipv4_route_table);
3046 }
3047 #endif