net/ipv4/route.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * INET         An implementation of the TCP/IP protocol suite for the LINUX
   4  *              operating system.  INET is implemented using the  BSD Socket
   5  *              interface as the means of communication with the user level.
   6  *
   7  *              ROUTE - implementation of the IP router.
   8  *
   9  * Authors:     Ross Biro
  10  *              Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
  11  *              Alan Cox, <gw4pts@gw4pts.ampr.org>
  12  *              Linus Torvalds, <Linus.Torvalds@helsinki.fi>
  13  *              Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
  14  *
  15  * Fixes:
  16  *              Alan Cox        :       Verify area fixes.
  17  *              Alan Cox        :       cli() protects routing changes
  18  *              Rui Oliveira    :       ICMP routing table updates
  19  *              (rco@di.uminho.pt)      Routing table insertion and update
  20  *              Linus Torvalds  :       Rewrote bits to be sensible
  21  *              Alan Cox        :       Added BSD route gw semantics
  22  *              Alan Cox        :       Super /proc >4K
  23  *              Alan Cox        :       MTU in route table
  24  *              Alan Cox        :       MSS actually. Also added the window
  25  *                                      clamper.
  26  *              Sam Lantinga    :       Fixed route matching in rt_del()
  27  *              Alan Cox        :       Routing cache support.
  28  *              Alan Cox        :       Removed compatibility cruft.
  29  *              Alan Cox        :       RTF_REJECT support.
  30  *              Alan Cox        :       TCP irtt support.
  31  *              Jonathan Naylor :       Added Metric support.
  32  *      Miquel van Smoorenburg  :       BSD API fixes.
  33  *      Miquel van Smoorenburg  :       Metrics.
  34  *              Alan Cox        :       Use __u32 properly
  35  *              Alan Cox        :       Aligned routing errors more closely with BSD
  36  *                                      our system is still very different.
  37  *              Alan Cox        :       Faster /proc handling
  38  *      Alexey Kuznetsov        :       Massive rework to support tree based routing,
  39  *                                      routing caches and better behaviour.
  40  *
  41  *              Olaf Erb        :       irtt wasn't being copied right.
  42  *              Bjorn Ekwall    :       Kerneld route support.
  43  *              Alan Cox        :       Multicast fixed (I hope)
  44  *              Pavel Krauz     :       Limited broadcast fixed
  45  *              Mike McLagan    :       Routing by source
  46  *      Alexey Kuznetsov        :       End of old history. Split to fib.c and
  47  *                                      route.c and rewritten from scratch.
  48  *              Andi Kleen      :       Load-limit warning messages.
  49  *      Vitaly E. Lavrov        :       Transparent proxy revived after year coma.
  50  *      Vitaly E. Lavrov        :       Race condition in ip_route_input_slow.
  51  *      Tobias Ringstrom        :       Uninitialized res.type in ip_route_output_slow.
  52  *      Vladimir V. Ivanov      :       IP rule info (flowid) is really useful.
  53  *              Marc Boucher    :       routing by fwmark
  54  *      Robert Olsson           :       Added rt_cache statistics
  55  *      Arnaldo C. Melo         :       Convert proc stuff to seq_file
  56  *      Eric Dumazet            :       hashed spinlocks and rt_check_expire() fixes.
  57  *      Ilia Sotnikov           :       Ignore TOS on PMTUD and Redirect
  58  *      Ilia Sotnikov           :       Removed TOS from hash calculations
  59  */
  60
  61 #define pr_fmt(fmt) "IPv4: " fmt
  62
  63 #include <linux/module.h>
  64 #include <linux/uaccess.h>
  65 #include <linux/bitops.h>
  66 #include <linux/types.h>
  67 #include <linux/kernel.h>
  68 #include <linux/mm.h>
  69 #include <linux/string.h>
  70 #include <linux/socket.h>
  71 #include <linux/sockios.h>
  72 #include <linux/errno.h>
  73 #include <linux/in.h>
  74 #include <linux/inet.h>
  75 #include <linux/netdevice.h>
  76 #include <linux/proc_fs.h>
  77 #include <linux/init.h>
  78 #include <linux/skbuff.h>
  79 #include <linux/inetdevice.h>
  80 #include <linux/igmp.h>
  81 #include <linux/pkt_sched.h>
  82 #include <linux/mroute.h>
  83 #include <linux/netfilter_ipv4.h>
  84 #include <linux/random.h>
  85 #include <linux/rcupdate.h>
  86 #include <linux/times.h>
  87 #include <linux/slab.h>
  88 #include <linux/jhash.h>
  89 #include <net/dst.h>
  90 #include <net/dst_metadata.h>
  91 #include <net/net_namespace.h>
  92 #include <net/protocol.h>
  93 #include <net/ip.h>
  94 #include <net/route.h>
  95 #include <net/inetpeer.h>
  96 #include <net/sock.h>
  97 #include <net/ip_fib.h>
  98 #include <net/nexthop.h>
  99 #include <net/arp.h>
 100 #include <net/tcp.h>
 101 #include <net/icmp.h>
 102 #include <net/xfrm.h>
 103 #include <net/lwtunnel.h>
 104 #include <net/netevent.h>
 105 #include <net/rtnetlink.h>
 106 #ifdef CONFIG_SYSCTL
 107 #include <linux/sysctl.h>
 108 #endif
 109 #include <net/secure_seq.h>
 110 #include <net/ip_tunnels.h>
 111 #include <net/l3mdev.h>
 112
 113 #include "fib_lookup.h"
 114
 115 #define RT_FL_TOS(oldflp4) \
 116         ((oldflp4)->flowi4_tos & (IPTOS_RT_MASK | RTO_ONLINK))
 117
 118 #define RT_GC_TIMEOUT (300*HZ)
 119
 120 static int ip_rt_max_size;
 121 static int ip_rt_redirect_number __read_mostly  = 9;
 122 static int ip_rt_redirect_load __read_mostly    = HZ / 50;
 123 static int ip_rt_redirect_silence __read_mostly = ((HZ / 50) << (9 + 1));
 124 static int ip_rt_error_cost __read_mostly       = HZ;
 125 static int ip_rt_error_burst __read_mostly      = 5 * HZ;
 126 static int ip_rt_mtu_expires __read_mostly      = 10 * 60 * HZ;
 127 static u32 ip_rt_min_pmtu __read_mostly         = 512 + 20 + 20;
 128 static int ip_rt_min_advmss __read_mostly       = 256;
 129
 130 static int ip_rt_gc_timeout __read_mostly       = RT_GC_TIMEOUT;
 131
 132 /*
 133  *      Interface to generic destination cache.
 134  */
 135
 136 static struct dst_entry *ipv4_dst_check(struct dst_entry *dst, u32 cookie);
 137 static unsigned int      ipv4_default_advmss(const struct dst_entry *dst);
 138 static unsigned int      ipv4_mtu(const struct dst_entry *dst);
 139 static struct dst_entry *ipv4_negative_advice(struct dst_entry *dst);
 140 static void              ipv4_link_failure(struct sk_buff *skb);
 141 static void              ip_rt_update_pmtu(struct dst_entry *dst, struct sock *sk,
 142                                            struct sk_buff *skb, u32 mtu);
 143 static void              ip_do_redirect(struct dst_entry *dst, struct sock *sk,
 144                                         struct sk_buff *skb);
 145 static void             ipv4_dst_destroy(struct dst_entry *dst);
 146
 147 static u32 *ipv4_cow_metrics(struct dst_entry *dst, unsigned long old)
 148 {
 149         WARN_ON(1);
 150         return NULL;
 151 }
 152
 153 static struct neighbour *ipv4_neigh_lookup(const struct dst_entry *dst,
 154                                            struct sk_buff *skb,
 155                                            const void *daddr);
 156 static void ipv4_confirm_neigh(const struct dst_entry *dst, const void *daddr);
 157
 158 static struct dst_ops ipv4_dst_ops = {
 159         .family =               AF_INET,
 160         .check =                ipv4_dst_check,
 161         .default_advmss =       ipv4_default_advmss,
 162         .mtu =                  ipv4_mtu,
 163         .cow_metrics =          ipv4_cow_metrics,
 164         .destroy =              ipv4_dst_destroy,
 165         .negative_advice =      ipv4_negative_advice,
 166         .link_failure =         ipv4_link_failure,
 167         .update_pmtu =          ip_rt_update_pmtu,
 168         .redirect =             ip_do_redirect,
 169         .local_out =            __ip_local_out,
 170         .neigh_lookup =         ipv4_neigh_lookup,
 171         .confirm_neigh =        ipv4_confirm_neigh,
 172 };
 173
 174 #define ECN_OR_COST(class)      TC_PRIO_##class
 175
 176 const __u8 ip_tos2prio[16] = {
 177         TC_PRIO_BESTEFFORT,
 178         ECN_OR_COST(BESTEFFORT),
 179         TC_PRIO_BESTEFFORT,
 180         ECN_OR_COST(BESTEFFORT),
 181         TC_PRIO_BULK,
 182         ECN_OR_COST(BULK),
 183         TC_PRIO_BULK,
 184         ECN_OR_COST(BULK),
 185         TC_PRIO_INTERACTIVE,
 186         ECN_OR_COST(INTERACTIVE),
 187         TC_PRIO_INTERACTIVE,
 188         ECN_OR_COST(INTERACTIVE),
 189         TC_PRIO_INTERACTIVE_BULK,
 190         ECN_OR_COST(INTERACTIVE_BULK),
 191         TC_PRIO_INTERACTIVE_BULK,
 192         ECN_OR_COST(INTERACTIVE_BULK)
 193 };
 194 EXPORT_SYMBOL(ip_tos2prio);
 195
 196 static DEFINE_PER_CPU(struct rt_cache_stat, rt_cache_stat);
 197 #define RT_CACHE_STAT_INC(field) raw_cpu_inc(rt_cache_stat.field)
 198
 199 #ifdef CONFIG_PROC_FS
 200 static void *rt_cache_seq_start(struct seq_file *seq, loff_t *pos)
 201 {
 202         if (*pos)
 203                 return NULL;
 204         return SEQ_START_TOKEN;
 205 }
 206
 207 static void *rt_cache_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 208 {
 209         ++*pos;
 210         return NULL;
 211 }
 212
 213 static void rt_cache_seq_stop(struct seq_file *seq, void *v)
 214 {
 215 }
 216
 217 static int rt_cache_seq_show(struct seq_file *seq, void *v)
 218 {
 219         if (v == SEQ_START_TOKEN)
 220                 seq_printf(seq, "%-127s\n",
 221                            "Iface\tDestination\tGateway \tFlags\t\tRefCnt\tUse\t"
 222                            "Metric\tSource\t\tMTU\tWindow\tIRTT\tTOS\tHHRef\t"
 223                            "HHUptod\tSpecDst");
 224         return 0;
 225 }
 226
 227 static const struct seq_operations rt_cache_seq_ops = {
 228         .start  = rt_cache_seq_start,
 229         .next   = rt_cache_seq_next,
 230         .stop   = rt_cache_seq_stop,
 231         .show   = rt_cache_seq_show,
 232 };
 233
 234 static int rt_cache_seq_open(struct inode *inode, struct file *file)
 235 {
 236         return seq_open(file, &rt_cache_seq_ops);
 237 }
 238
 239 static const struct file_operations rt_cache_seq_fops = {
 240         .open    = rt_cache_seq_open,
 241         .read    = seq_read,
 242         .llseek  = seq_lseek,
 243         .release = seq_release,
 244 };
 245
 246
 247 static void *rt_cpu_seq_start(struct seq_file *seq, loff_t *pos)
 248 {
 249         int cpu;
 250
 251         if (*pos == 0)
 252                 return SEQ_START_TOKEN;
 253
 254         for (cpu = *pos-1; cpu < nr_cpu_ids; ++cpu) {
 255                 if (!cpu_possible(cpu))
 256                         continue;
 257                 *pos = cpu+1;
 258                 return &per_cpu(rt_cache_stat, cpu);
 259         }
 260         return NULL;
 261 }
 262
 263 static void *rt_cpu_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 264 {
 265         int cpu;
 266
 267         for (cpu = *pos; cpu < nr_cpu_ids; ++cpu) {
 268                 if (!cpu_possible(cpu))
 269                         continue;
 270                 *pos = cpu+1;
 271                 return &per_cpu(rt_cache_stat, cpu);
 272         }
 273         return NULL;
 274
 275 }
 276
 277 static void rt_cpu_seq_stop(struct seq_file *seq, void *v)
 278 {
 279
 280 }
 281
 282 static int rt_cpu_seq_show(struct seq_file *seq, void *v)
 283 {
 284         struct rt_cache_stat *st = v;
 285
 286         if (v == SEQ_START_TOKEN) {
 287                 seq_printf(seq, "entries  in_hit in_slow_tot in_slow_mc in_no_route in_brd in_martian_dst in_martian_src  out_hit out_slow_tot out_slow_mc  gc_total gc_ignored gc_goal_miss gc_dst_overflow in_hlist_search out_hlist_search\n");
 288                 return 0;
 289         }
 290
 291         seq_printf(seq,"%08x  %08x %08x %08x %08x %08x %08x %08x "
 292                    " %08x %08x %08x %08x %08x %08x %08x %08x %08x \n",
 293                    dst_entries_get_slow(&ipv4_dst_ops),
 294                    0, /* st->in_hit */
 295                    st->in_slow_tot,
 296                    st->in_slow_mc,
 297                    st->in_no_route,
 298                    st->in_brd,
 299                    st->in_martian_dst,
 300                    st->in_martian_src,
 301
 302                    0, /* st->out_hit */
 303                    st->out_slow_tot,
 304                    st->out_slow_mc,
 305
 306                    0, /* st->gc_total */
 307                    0, /* st->gc_ignored */
 308                    0, /* st->gc_goal_miss */
 309                    0, /* st->gc_dst_overflow */
 310                    0, /* st->in_hlist_search */
 311                    0  /* st->out_hlist_search */
 312                 );
 313         return 0;
 314 }
 315
 316 static const struct seq_operations rt_cpu_seq_ops = {
 317         .start  = rt_cpu_seq_start,
 318         .next   = rt_cpu_seq_next,
 319         .stop   = rt_cpu_seq_stop,
 320         .show   = rt_cpu_seq_show,
 321 };
 322
 323
 324 static int rt_cpu_seq_open(struct inode *inode, struct file *file)
 325 {
 326         return seq_open(file, &rt_cpu_seq_ops);
 327 }
 328
 329 static const struct file_operations rt_cpu_seq_fops = {
 330         .open    = rt_cpu_seq_open,
 331         .read    = seq_read,
 332         .llseek  = seq_lseek,
 333         .release = seq_release,
 334 };
 335
 336 #ifdef CONFIG_IP_ROUTE_CLASSID
 337 static int rt_acct_proc_show(struct seq_file *m, void *v)
 338 {
 339         struct ip_rt_acct *dst, *src;
 340         unsigned int i, j;
 341
 342         dst = kcalloc(256, sizeof(struct ip_rt_acct), GFP_KERNEL);
 343         if (!dst)
 344                 return -ENOMEM;
 345
 346         for_each_possible_cpu(i) {
 347                 src = (struct ip_rt_acct *)per_cpu_ptr(ip_rt_acct, i);
 348                 for (j = 0; j < 256; j++) {
 349                         dst[j].o_bytes   += src[j].o_bytes;
 350                         dst[j].o_packets += src[j].o_packets;
 351                         dst[j].i_bytes   += src[j].i_bytes;
 352                         dst[j].i_packets += src[j].i_packets;
 353                 }
 354         }
 355
 356         seq_write(m, dst, 256 * sizeof(struct ip_rt_acct));
 357         kfree(dst);
 358         return 0;
 359 }
 360 #endif
 361
 362 static int __net_init ip_rt_do_proc_init(struct net *net)
 363 {
 364         struct proc_dir_entry *pde;
 365
 366         pde = proc_create("rt_cache", 0444, net->proc_net,
 367                           &rt_cache_seq_fops);
 368         if (!pde)
 369                 goto err1;
 370
 371         pde = proc_create("rt_cache", 0444,
 372                           net->proc_net_stat, &rt_cpu_seq_fops);
 373         if (!pde)
 374                 goto err2;
 375
 376 #ifdef CONFIG_IP_ROUTE_CLASSID
 377         pde = proc_create_single("rt_acct", 0, net->proc_net,
 378                         rt_acct_proc_show);
 379         if (!pde)
 380                 goto err3;
 381 #endif
 382         return 0;
 383
 384 #ifdef CONFIG_IP_ROUTE_CLASSID
 385 err3:
 386         remove_proc_entry("rt_cache", net->proc_net_stat);
 387 #endif
 388 err2:
 389         remove_proc_entry("rt_cache", net->proc_net);
 390 err1:
 391         return -ENOMEM;
 392 }
 393
 394 static void __net_exit ip_rt_do_proc_exit(struct net *net)
 395 {
 396         remove_proc_entry("rt_cache", net->proc_net_stat);
 397         remove_proc_entry("rt_cache", net->proc_net);
 398 #ifdef CONFIG_IP_ROUTE_CLASSID
 399         remove_proc_entry("rt_acct", net->proc_net);
 400 #endif
 401 }
 402
 403 static struct pernet_operations ip_rt_proc_ops __net_initdata =  {
 404         .init = ip_rt_do_proc_init,
 405         .exit = ip_rt_do_proc_exit,
 406 };
 407
 408 static int __init ip_rt_proc_init(void)
 409 {
 410         return register_pernet_subsys(&ip_rt_proc_ops);
 411 }
 412
 413 #else
 414 static inline int ip_rt_proc_init(void)
 415 {
 416         return 0;
 417 }
 418 #endif /* CONFIG_PROC_FS */
 419
 420 static inline bool rt_is_expired(const struct rtable *rth)
 421 {
 422         return rth->rt_genid != rt_genid_ipv4(dev_net(rth->dst.dev));
 423 }
 424
 425 void rt_cache_flush(struct net *net)
 426 {
 427         rt_genid_bump_ipv4(net);
 428 }
 429
 430 static struct neighbour *ipv4_neigh_lookup(const struct dst_entry *dst,
 431                                            struct sk_buff *skb,
 432                                            const void *daddr)
 433 {
 434         const struct rtable *rt = container_of(dst, struct rtable, dst);
 435         struct net_device *dev = dst->dev;
 436         struct neighbour *n;
 437
 438         rcu_read_lock_bh();
 439
 440         if (likely(rt->rt_gw_family == AF_INET)) {
 441                 n = ip_neigh_gw4(dev, rt->rt_gw4);
 442         } else if (rt->rt_gw_family == AF_INET6) {
 443                 n = ip_neigh_gw6(dev, &rt->rt_gw6);
 444         } else {
 445                 __be32 pkey;
 446
 447                 pkey = skb ? ip_hdr(skb)->daddr : *((__be32 *) daddr);
 448                 n = ip_neigh_gw4(dev, pkey);
 449         }
 450
 451         if (!IS_ERR(n) && !refcount_inc_not_zero(&n->refcnt))
 452                 n = NULL;
 453
 454         rcu_read_unlock_bh();
 455
 456         return n;
 457 }
 458
 459 static void ipv4_confirm_neigh(const struct dst_entry *dst, const void *daddr)
 460 {
 461         const struct rtable *rt = container_of(dst, struct rtable, dst);
 462         struct net_device *dev = dst->dev;
 463         const __be32 *pkey = daddr;
 464
 465         if (rt->rt_gw_family == AF_INET) {
 466                 pkey = (const __be32 *)&rt->rt_gw4;
 467         } else if (rt->rt_gw_family == AF_INET6) {
 468                 return __ipv6_confirm_neigh_stub(dev, &rt->rt_gw6);
 469         } else if (!daddr ||
 470                  (rt->rt_flags &
 471                   (RTCF_MULTICAST | RTCF_BROADCAST | RTCF_LOCAL))) {
 472                 return;
 473         }
 474         __ipv4_confirm_neigh(dev, *(__force u32 *)pkey);
 475 }
 476
 477 #define IP_IDENTS_SZ 2048u
 478
 479 static atomic_t *ip_idents __read_mostly;
 480 static u32 *ip_tstamps __read_mostly;
 481
 482 /* In order to protect privacy, we add a perturbation to identifiers
 483  * if one generator is seldom used. This makes hard for an attacker
 484  * to infer how many packets were sent between two points in time.
 485  */
 486 u32 ip_idents_reserve(u32 hash, int segs)
 487 {
 488         u32 *p_tstamp = ip_tstamps + hash % IP_IDENTS_SZ;
 489         atomic_t *p_id = ip_idents + hash % IP_IDENTS_SZ;
 490         u32 old = READ_ONCE(*p_tstamp);
 491         u32 now = (u32)jiffies;
 492         u32 new, delta = 0;
 493
 494         if (old != now && cmpxchg(p_tstamp, old, now) == old)
 495                 delta = prandom_u32_max(now - old);
 496
 497         /* Do not use atomic_add_return() as it makes UBSAN unhappy */
 498         do {
 499                 old = (u32)atomic_read(p_id);
 500                 new = old + delta + segs;
 501         } while (atomic_cmpxchg(p_id, old, new) != old);
 502
 503         return new - segs;
 504 }
 505 EXPORT_SYMBOL(ip_idents_reserve);
 506
 507 void __ip_select_ident(struct net *net, struct iphdr *iph, int segs)
 508 {
 509         u32 hash, id;
 510
 511         /* Note the following code is not safe, but this is okay. */
 512         if (unlikely(siphash_key_is_zero(&net->ipv4.ip_id_key)))
 513                 get_random_bytes(&net->ipv4.ip_id_key,
 514                                  sizeof(net->ipv4.ip_id_key));
 515
 516         hash = siphash_3u32((__force u32)iph->daddr,
 517                             (__force u32)iph->saddr,
 518                             iph->protocol,
 519                             &net->ipv4.ip_id_key);
 520         id = ip_idents_reserve(hash, segs);
 521         iph->id = htons(id);
 522 }
 523 EXPORT_SYMBOL(__ip_select_ident);
 524
 525 static void __build_flow_key(const struct net *net, struct flowi4 *fl4,
 526                              const struct sock *sk,
 527                              const struct iphdr *iph,
 528                              int oif, u8 tos,
 529                              u8 prot, u32 mark, int flow_flags)
 530 {
 531         if (sk) {
 532                 const struct inet_sock *inet = inet_sk(sk);
 533
 534                 oif = sk->sk_bound_dev_if;
 535                 mark = sk->sk_mark;
 536                 tos = RT_CONN_FLAGS(sk);
 537                 prot = inet->hdrincl ? IPPROTO_RAW : sk->sk_protocol;
 538         }
 539         flowi4_init_output(fl4, oif, mark, tos,
 540                            RT_SCOPE_UNIVERSE, prot,
 541                            flow_flags,
 542                            iph->daddr, iph->saddr, 0, 0,
 543                            sock_net_uid(net, sk));
 544 }
 545
 546 static void build_skb_flow_key(struct flowi4 *fl4, const struct sk_buff *skb,
 547                                const struct sock *sk)
 548 {
 549         const struct net *net = dev_net(skb->dev);
 550         const struct iphdr *iph = ip_hdr(skb);
 551         int oif = skb->dev->ifindex;
 552         u8 tos = RT_TOS(iph->tos);
 553         u8 prot = iph->protocol;
 554         u32 mark = skb->mark;
 555
 556         __build_flow_key(net, fl4, sk, iph, oif, tos, prot, mark, 0);
 557 }
 558
 559 static void build_sk_flow_key(struct flowi4 *fl4, const struct sock *sk)
 560 {
 561         const struct inet_sock *inet = inet_sk(sk);
 562         const struct ip_options_rcu *inet_opt;
 563         __be32 daddr = inet->inet_daddr;
 564
 565         rcu_read_lock();
 566         inet_opt = rcu_dereference(inet->inet_opt);
 567         if (inet_opt && inet_opt->opt.srr)
 568                 daddr = inet_opt->opt.faddr;
 569         flowi4_init_output(fl4, sk->sk_bound_dev_if, sk->sk_mark,
 570                            RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE,
 571                            inet->hdrincl ? IPPROTO_RAW : sk->sk_protocol,
 572                            inet_sk_flowi_flags(sk),
 573                            daddr, inet->inet_saddr, 0, 0, sk->sk_uid);
 574         rcu_read_unlock();
 575 }
 576
 577 static void ip_rt_build_flow_key(struct flowi4 *fl4, const struct sock *sk,
 578                                  const struct sk_buff *skb)
 579 {
 580         if (skb)
 581                 build_skb_flow_key(fl4, skb, sk);
 582         else
 583                 build_sk_flow_key(fl4, sk);
 584 }
 585
 586 static DEFINE_SPINLOCK(fnhe_lock);
 587
 588 static void fnhe_flush_routes(struct fib_nh_exception *fnhe)
 589 {
 590         struct rtable *rt;
 591
 592         rt = rcu_dereference(fnhe->fnhe_rth_input);
 593         if (rt) {
 594                 RCU_INIT_POINTER(fnhe->fnhe_rth_input, NULL);
 595                 dst_dev_put(&rt->dst);
 596                 dst_release(&rt->dst);
 597         }
 598         rt = rcu_dereference(fnhe->fnhe_rth_output);
 599         if (rt) {
 600                 RCU_INIT_POINTER(fnhe->fnhe_rth_output, NULL);
 601                 dst_dev_put(&rt->dst);
 602                 dst_release(&rt->dst);
 603         }
 604 }
 605
 606 static struct fib_nh_exception *fnhe_oldest(struct fnhe_hash_bucket *hash)
 607 {
 608         struct fib_nh_exception *fnhe, *oldest;
 609
 610         oldest = rcu_dereference(hash->chain);
 611         for (fnhe = rcu_dereference(oldest->fnhe_next); fnhe;
 612              fnhe = rcu_dereference(fnhe->fnhe_next)) {
 613                 if (time_before(fnhe->fnhe_stamp, oldest->fnhe_stamp))
 614                         oldest = fnhe;
 615         }
 616         fnhe_flush_routes(oldest);
 617         return oldest;
 618 }
 619
 620 static inline u32 fnhe_hashfun(__be32 daddr)
 621 {
 622         static u32 fnhe_hashrnd __read_mostly;
 623         u32 hval;
 624
 625         net_get_random_once(&fnhe_hashrnd, sizeof(fnhe_hashrnd));
 626         hval = jhash_1word((__force u32) daddr, fnhe_hashrnd);
 627         return hash_32(hval, FNHE_HASH_SHIFT);
 628 }
 629
 630 static void fill_route_from_fnhe(struct rtable *rt, struct fib_nh_exception *fnhe)
 631 {
 632         rt->rt_pmtu = fnhe->fnhe_pmtu;
 633         rt->rt_mtu_locked = fnhe->fnhe_mtu_locked;
 634         rt->dst.expires = fnhe->fnhe_expires;
 635
 636         if (fnhe->fnhe_gw) {
 637                 rt->rt_flags |= RTCF_REDIRECTED;
 638                 rt->rt_uses_gateway = 1;
 639                 rt->rt_gw_family = AF_INET;
 640                 rt->rt_gw4 = fnhe->fnhe_gw;
 641         }
 642 }
 643
 644 static void update_or_create_fnhe(struct fib_nh_common *nhc, __be32 daddr,
 645                                   __be32 gw, u32 pmtu, bool lock,
 646                                   unsigned long expires)
 647 {
 648         struct fnhe_hash_bucket *hash;
 649         struct fib_nh_exception *fnhe;
 650         struct rtable *rt;
 651         u32 genid, hval;
 652         unsigned int i;
 653         int depth;
 654
 655         genid = fnhe_genid(dev_net(nhc->nhc_dev));
 656         hval = fnhe_hashfun(daddr);
 657
 658         spin_lock_bh(&fnhe_lock);
 659
 660         hash = rcu_dereference(nhc->nhc_exceptions);
 661         if (!hash) {
 662                 hash = kcalloc(FNHE_HASH_SIZE, sizeof(*hash), GFP_ATOMIC);
 663                 if (!hash)
 664                         goto out_unlock;
 665                 rcu_assign_pointer(nhc->nhc_exceptions, hash);
 666         }
 667
 668         hash += hval;
 669
 670         depth = 0;
 671         for (fnhe = rcu_dereference(hash->chain); fnhe;
 672              fnhe = rcu_dereference(fnhe->fnhe_next)) {
 673                 if (fnhe->fnhe_daddr == daddr)
 674                         break;
 675                 depth++;
 676         }
 677
 678         if (fnhe) {
 679                 if (fnhe->fnhe_genid != genid)
 680                         fnhe->fnhe_genid = genid;
 681                 if (gw)
 682                         fnhe->fnhe_gw = gw;
 683                 if (pmtu) {
 684                         fnhe->fnhe_pmtu = pmtu;
 685                         fnhe->fnhe_mtu_locked = lock;
 686                 }
 687                 fnhe->fnhe_expires = max(1UL, expires);
 688                 /* Update all cached dsts too */
 689                 rt = rcu_dereference(fnhe->fnhe_rth_input);
 690                 if (rt)
 691                         fill_route_from_fnhe(rt, fnhe);
 692                 rt = rcu_dereference(fnhe->fnhe_rth_output);
 693                 if (rt)
 694                         fill_route_from_fnhe(rt, fnhe);
 695         } else {
 696                 if (depth > FNHE_RECLAIM_DEPTH)
 697                         fnhe = fnhe_oldest(hash);
 698                 else {
 699                         fnhe = kzalloc(sizeof(*fnhe), GFP_ATOMIC);
 700                         if (!fnhe)
 701                                 goto out_unlock;
 702
 703                         fnhe->fnhe_next = hash->chain;
 704                         rcu_assign_pointer(hash->chain, fnhe);
 705                 }
 706                 fnhe->fnhe_genid = genid;
 707                 fnhe->fnhe_daddr = daddr;
 708                 fnhe->fnhe_gw = gw;
 709                 fnhe->fnhe_pmtu = pmtu;
 710                 fnhe->fnhe_mtu_locked = lock;
 711                 fnhe->fnhe_expires = max(1UL, expires);
 712
 713                 /* Exception created; mark the cached routes for the nexthop
 714                  * stale, so anyone caching it rechecks if this exception
 715                  * applies to them.
 716                  */
 717                 rt = rcu_dereference(nhc->nhc_rth_input);
 718                 if (rt)
 719                         rt->dst.obsolete = DST_OBSOLETE_KILL;
 720
 721                 for_each_possible_cpu(i) {
 722                         struct rtable __rcu **prt;
 723                         prt = per_cpu_ptr(nhc->nhc_pcpu_rth_output, i);
 724                         rt = rcu_dereference(*prt);
 725                         if (rt)
 726                                 rt->dst.obsolete = DST_OBSOLETE_KILL;
 727                 }
 728         }
 729
 730         fnhe->fnhe_stamp = jiffies;
 731
 732 out_unlock:
 733         spin_unlock_bh(&fnhe_lock);
 734 }
 735
 736 static void __ip_do_redirect(struct rtable *rt, struct sk_buff *skb, struct flowi4 *fl4,
 737                              bool kill_route)
 738 {
 739         __be32 new_gw = icmp_hdr(skb)->un.gateway;
 740         __be32 old_gw = ip_hdr(skb)->saddr;
 741         struct net_device *dev = skb->dev;
 742         struct in_device *in_dev;
 743         struct fib_result res;
 744         struct neighbour *n;
 745         struct net *net;
 746
 747         switch (icmp_hdr(skb)->code & 7) {
 748         case ICMP_REDIR_NET:
 749         case ICMP_REDIR_NETTOS:
 750         case ICMP_REDIR_HOST:
 751         case ICMP_REDIR_HOSTTOS:
 752                 break;
 753
 754         default:
 755                 return;
 756         }
 757
 758         if (rt->rt_gw_family != AF_INET || rt->rt_gw4 != old_gw)
 759                 return;
 760
 761         in_dev = __in_dev_get_rcu(dev);
 762         if (!in_dev)
 763                 return;
 764
 765         net = dev_net(dev);
 766         if (new_gw == old_gw || !IN_DEV_RX_REDIRECTS(in_dev) ||
 767             ipv4_is_multicast(new_gw) || ipv4_is_lbcast(new_gw) ||
 768             ipv4_is_zeronet(new_gw))
 769                 goto reject_redirect;
 770
 771         if (!IN_DEV_SHARED_MEDIA(in_dev)) {
 772                 if (!inet_addr_onlink(in_dev, new_gw, old_gw))
 773                         goto reject_redirect;
 774                 if (IN_DEV_SEC_REDIRECTS(in_dev) && ip_fib_check_default(new_gw, dev))
 775                         goto reject_redirect;
 776         } else {
 777                 if (inet_addr_type(net, new_gw) != RTN_UNICAST)
 778                         goto reject_redirect;
 779         }
 780
 781         n = __ipv4_neigh_lookup(rt->dst.dev, new_gw);
 782         if (!n)
 783                 n = neigh_create(&arp_tbl, &new_gw, rt->dst.dev);
 784         if (!IS_ERR(n)) {
 785                 if (!(n->nud_state & NUD_VALID)) {
 786                         neigh_event_send(n, NULL);
 787                 } else {
 788                         if (fib_lookup(net, fl4, &res, 0) == 0) {
 789                                 struct fib_nh_common *nhc = FIB_RES_NHC(res);
 790
 791                                 update_or_create_fnhe(nhc, fl4->daddr, new_gw,
 792                                                 0, false,
 793                                                 jiffies + ip_rt_gc_timeout);
 794                         }
 795                         if (kill_route)
 796                                 rt->dst.obsolete = DST_OBSOLETE_KILL;
 797                         call_netevent_notifiers(NETEVENT_NEIGH_UPDATE, n);
 798                 }
 799                 neigh_release(n);
 800         }
 801         return;
 802
 803 reject_redirect:
 804 #ifdef CONFIG_IP_ROUTE_VERBOSE
 805         if (IN_DEV_LOG_MARTIANS(in_dev)) {
 806                 const struct iphdr *iph = (const struct iphdr *) skb->data;
 807                 __be32 daddr = iph->daddr;
 808                 __be32 saddr = iph->saddr;
 809
 810                 net_info_ratelimited("Redirect from %pI4 on %s about %pI4 ignored\n"
 811                                      "  Advised path = %pI4 -> %pI4\n",
 812                                      &old_gw, dev->name, &new_gw,
 813                                      &saddr, &daddr);
 814         }
 815 #endif
 816         ;
 817 }
 818
 819 static void ip_do_redirect(struct dst_entry *dst, struct sock *sk, struct sk_buff *skb)
 820 {
 821         struct rtable *rt;
 822         struct flowi4 fl4;
 823         const struct iphdr *iph = (const struct iphdr *) skb->data;
 824         struct net *net = dev_net(skb->dev);
 825         int oif = skb->dev->ifindex;
 826         u8 tos = RT_TOS(iph->tos);
 827         u8 prot = iph->protocol;
 828         u32 mark = skb->mark;
 829
 830         rt = (struct rtable *) dst;
 831
 832         __build_flow_key(net, &fl4, sk, iph, oif, tos, prot, mark, 0);
 833         __ip_do_redirect(rt, skb, &fl4, true);
 834 }
 835
 836 static struct dst_entry *ipv4_negative_advice(struct dst_entry *dst)
 837 {
 838         struct rtable *rt = (struct rtable *)dst;
 839         struct dst_entry *ret = dst;
 840
 841         if (rt) {
 842                 if (dst->obsolete > 0) {
 843                         ip_rt_put(rt);
 844                         ret = NULL;
 845                 } else if ((rt->rt_flags & RTCF_REDIRECTED) ||
 846                            rt->dst.expires) {
 847                         ip_rt_put(rt);
 848                         ret = NULL;
 849                 }
 850         }
 851         return ret;
 852 }
 853
 854 /*
 855  * Algorithm:
 856  *      1. The first ip_rt_redirect_number redirects are sent
 857  *         with exponential backoff, then we stop sending them at all,
 858  *         assuming that the host ignores our redirects.
 859  *      2. If we did not see packets requiring redirects
 860  *         during ip_rt_redirect_silence, we assume that the host
 861  *         forgot redirected route and start to send redirects again.
 862  *
 863  * This algorithm is much cheaper and more intelligent than dumb load limiting
 864  * in icmp.c.
 865  *
 866  * NOTE. Do not forget to inhibit load limiting for redirects (redundant)
 867  * and "frag. need" (breaks PMTU discovery) in icmp.c.
 868  */
 869
 870 void ip_rt_send_redirect(struct sk_buff *skb)
 871 {
 872         struct rtable *rt = skb_rtable(skb);
 873         struct in_device *in_dev;
 874         struct inet_peer *peer;
 875         struct net *net;
 876         int log_martians;
 877         int vif;
 878
 879         rcu_read_lock();
 880         in_dev = __in_dev_get_rcu(rt->dst.dev);
 881         if (!in_dev || !IN_DEV_TX_REDIRECTS(in_dev)) {
 882                 rcu_read_unlock();
 883                 return;
 884         }
 885         log_martians = IN_DEV_LOG_MARTIANS(in_dev);
 886         vif = l3mdev_master_ifindex_rcu(rt->dst.dev);
 887         rcu_read_unlock();
 888
 889         net = dev_net(rt->dst.dev);
 890         peer = inet_getpeer_v4(net->ipv4.peers, ip_hdr(skb)->saddr, vif, 1);
 891         if (!peer) {
 892                 icmp_send(skb, ICMP_REDIRECT, ICMP_REDIR_HOST,
 893                           rt_nexthop(rt, ip_hdr(skb)->daddr));
 894                 return;
 895         }
 896
 897         /* No redirected packets during ip_rt_redirect_silence;
 898          * reset the algorithm.
 899          */
 900         if (time_after(jiffies, peer->rate_last + ip_rt_redirect_silence)) {
 901                 peer->rate_tokens = 0;
 902                 peer->n_redirects = 0;
 903         }
 904
 905         /* Too many ignored redirects; do not send anything
 906          * set dst.rate_last to the last seen redirected packet.
 907          */
 908         if (peer->n_redirects >= ip_rt_redirect_number) {
 909                 peer->rate_last = jiffies;
 910                 goto out_put_peer;
 911         }
 912
 913         /* Check for load limit; set rate_last to the latest sent
 914          * redirect.
 915          */
 916         if (peer->rate_tokens == 0 ||
 917             time_after(jiffies,
 918                        (peer->rate_last +
 919                         (ip_rt_redirect_load << peer->n_redirects)))) {
 920                 __be32 gw = rt_nexthop(rt, ip_hdr(skb)->daddr);
 921
 922                 icmp_send(skb, ICMP_REDIRECT, ICMP_REDIR_HOST, gw);
 923                 peer->rate_last = jiffies;
 924                 ++peer->n_redirects;
 925 #ifdef CONFIG_IP_ROUTE_VERBOSE
 926                 if (log_martians &&
 927                     peer->n_redirects == ip_rt_redirect_number)
 928                         net_warn_ratelimited("host %pI4/if%d ignores redirects for %pI4 to %pI4\n",
 929                                              &ip_hdr(skb)->saddr, inet_iif(skb),
 930                                              &ip_hdr(skb)->daddr, &gw);
 931 #endif
 932         }
 933 out_put_peer:
 934         inet_putpeer(peer);
 935 }
 936
 937 static int ip_error(struct sk_buff *skb)
 938 {
 939         struct rtable *rt = skb_rtable(skb);
 940         struct net_device *dev = skb->dev;
 941         struct in_device *in_dev;
 942         struct inet_peer *peer;
 943         unsigned long now;
 944         struct net *net;
 945         bool send;
 946         int code;
 947
 948         if (netif_is_l3_master(skb->dev)) {
 949                 dev = __dev_get_by_index(dev_net(skb->dev), IPCB(skb)->iif);
 950                 if (!dev)
 951                         goto out;
 952         }
 953
 954         in_dev = __in_dev_get_rcu(dev);
 955
 956         /* IP on this device is disabled. */
 957         if (!in_dev)
 958                 goto out;
 959
 960         net = dev_net(rt->dst.dev);
 961         if (!IN_DEV_FORWARD(in_dev)) {
 962                 switch (rt->dst.error) {
 963                 case EHOSTUNREACH:
 964                         __IP_INC_STATS(net, IPSTATS_MIB_INADDRERRORS);
 965                         break;
 966
 967                 case ENETUNREACH:
 968                         __IP_INC_STATS(net, IPSTATS_MIB_INNOROUTES);
 969                         break;
 970                 }
 971                 goto out;
 972         }
 973
 974         switch (rt->dst.error) {
 975         case EINVAL:
 976         default:
 977                 goto out;
 978         case EHOSTUNREACH:
 979                 code = ICMP_HOST_UNREACH;
 980                 break;
 981         case ENETUNREACH:
 982                 code = ICMP_NET_UNREACH;
 983                 __IP_INC_STATS(net, IPSTATS_MIB_INNOROUTES);
 984                 break;
 985         case EACCES:
 986                 code = ICMP_PKT_FILTERED;
 987                 break;
 988         }
 989
 990         peer = inet_getpeer_v4(net->ipv4.peers, ip_hdr(skb)->saddr,
 991                                l3mdev_master_ifindex(skb->dev), 1);
 992
 993         send = true;
 994         if (peer) {
 995                 now = jiffies;
 996                 peer->rate_tokens += now - peer->rate_last;
 997                 if (peer->rate_tokens > ip_rt_error_burst)
 998                         peer->rate_tokens = ip_rt_error_burst;
 999                 peer->rate_last = now;
1000                 if (peer->rate_tokens >= ip_rt_error_cost)
1001                         peer->rate_tokens -= ip_rt_error_cost;
1002                 else
1003                         send = false;
1004                 inet_putpeer(peer);
1005         }
1006         if (send)
1007                 icmp_send(skb, ICMP_DEST_UNREACH, code, 0);
1008
1009 out:    kfree_skb(skb);
1010         return 0;
1011 }
1012
1013 static void __ip_rt_update_pmtu(struct rtable *rt, struct flowi4 *fl4, u32 mtu)
1014 {
1015         struct dst_entry *dst = &rt->dst;
1016         u32 old_mtu = ipv4_mtu(dst);
1017         struct fib_result res;
1018         bool lock = false;
1019
1020         if (ip_mtu_locked(dst))
1021                 return;
1022
1023         if (old_mtu < mtu)
1024                 return;
1025
1026         if (mtu < ip_rt_min_pmtu) {
1027                 lock = true;
1028                 mtu = min(old_mtu, ip_rt_min_pmtu);
1029         }
1030
1031         if (rt->rt_pmtu == mtu && !lock &&
1032             time_before(jiffies, dst->expires - ip_rt_mtu_expires / 2))
1033                 return;
1034
1035         rcu_read_lock();
1036         if (fib_lookup(dev_net(dst->dev), fl4, &res, 0) == 0) {
1037                 struct fib_nh_common *nhc = FIB_RES_NHC(res);
1038
1039                 update_or_create_fnhe(nhc, fl4->daddr, 0, mtu, lock,
1040                                       jiffies + ip_rt_mtu_expires);
1041         }
1042         rcu_read_unlock();
1043 }
1044
1045 static void ip_rt_update_pmtu(struct dst_entry *dst, struct sock *sk,
1046                               struct sk_buff *skb, u32 mtu)
1047 {
1048         struct rtable *rt = (struct rtable *) dst;
1049         struct flowi4 fl4;
1050
1051         ip_rt_build_flow_key(&fl4, sk, skb);
1052         __ip_rt_update_pmtu(rt, &fl4, mtu);
1053 }
1054
1055 void ipv4_update_pmtu(struct sk_buff *skb, struct net *net, u32 mtu,
1056                       int oif, u8 protocol)
1057 {
1058         const struct iphdr *iph = (const struct iphdr *) skb->data;
1059         struct flowi4 fl4;
1060         struct rtable *rt;
1061         u32 mark = IP4_REPLY_MARK(net, skb->mark);
1062
1063         __build_flow_key(net, &fl4, NULL, iph, oif,
1064                          RT_TOS(iph->tos), protocol, mark, 0);
1065         rt = __ip_route_output_key(net, &fl4);
1066         if (!IS_ERR(rt)) {
1067                 __ip_rt_update_pmtu(rt, &fl4, mtu);
1068                 ip_rt_put(rt);
1069         }
1070 }
1071 EXPORT_SYMBOL_GPL(ipv4_update_pmtu);
1072
1073 static void __ipv4_sk_update_pmtu(struct sk_buff *skb, struct sock *sk, u32 mtu)
1074 {
1075         const struct iphdr *iph = (const struct iphdr *) skb->data;
1076         struct flowi4 fl4;
1077         struct rtable *rt;
1078
1079         __build_flow_key(sock_net(sk), &fl4, sk, iph, 0, 0, 0, 0, 0);
1080
1081         if (!fl4.flowi4_mark)
1082                 fl4.flowi4_mark = IP4_REPLY_MARK(sock_net(sk), skb->mark);
1083
1084         rt = __ip_route_output_key(sock_net(sk), &fl4);
1085         if (!IS_ERR(rt)) {
1086                 __ip_rt_update_pmtu(rt, &fl4, mtu);
1087                 ip_rt_put(rt);
1088         }
1089 }
1090
1091 void ipv4_sk_update_pmtu(struct sk_buff *skb, struct sock *sk, u32 mtu)
1092 {
1093         const struct iphdr *iph = (const struct iphdr *) skb->data;
1094         struct flowi4 fl4;
1095         struct rtable *rt;
1096         struct dst_entry *odst = NULL;
1097         bool new = false;
1098         struct net *net = sock_net(sk);
1099
1100         bh_lock_sock(sk);
1101
1102         if (!ip_sk_accept_pmtu(sk))
1103                 goto out;
1104
1105         odst = sk_dst_get(sk);
1106
1107         if (sock_owned_by_user(sk) || !odst) {
1108                 __ipv4_sk_update_pmtu(skb, sk, mtu);
1109                 goto out;
1110         }
1111
1112         __build_flow_key(net, &fl4, sk, iph, 0, 0, 0, 0, 0);
1113
1114         rt = (struct rtable *)odst;
1115         if (odst->obsolete && !odst->ops->check(odst, 0)) {
1116                 rt = ip_route_output_flow(sock_net(sk), &fl4, sk);
1117                 if (IS_ERR(rt))
1118                         goto out;
1119
1120                 new = true;
1121         }
1122
1123         __ip_rt_update_pmtu((struct rtable *) xfrm_dst_path(&rt->dst), &fl4, mtu);
1124
1125         if (!dst_check(&rt->dst, 0)) {
1126                 if (new)
1127                         dst_release(&rt->dst);
1128
1129                 rt = ip_route_output_flow(sock_net(sk), &fl4, sk);
1130                 if (IS_ERR(rt))
1131                         goto out;
1132
1133                 new = true;
1134         }
1135
1136         if (new)
1137                 sk_dst_set(sk, &rt->dst);
1138
1139 out:
1140         bh_unlock_sock(sk);
1141         dst_release(odst);
1142 }
1143 EXPORT_SYMBOL_GPL(ipv4_sk_update_pmtu);
1144
1145 void ipv4_redirect(struct sk_buff *skb, struct net *net,
1146                    int oif, u8 protocol)
1147 {
1148         const struct iphdr *iph = (const struct iphdr *) skb->data;
1149         struct flowi4 fl4;
1150         struct rtable *rt;
1151
1152         __build_flow_key(net, &fl4, NULL, iph, oif,
1153                          RT_TOS(iph->tos), protocol, 0, 0);
1154         rt = __ip_route_output_key(net, &fl4);
1155         if (!IS_ERR(rt)) {
1156                 __ip_do_redirect(rt, skb, &fl4, false);
1157                 ip_rt_put(rt);
1158         }
1159 }
1160 EXPORT_SYMBOL_GPL(ipv4_redirect);
1161
1162 void ipv4_sk_redirect(struct sk_buff *skb, struct sock *sk)
1163 {
1164         const struct iphdr *iph = (const struct iphdr *) skb->data;
1165         struct flowi4 fl4;
1166         struct rtable *rt;
1167         struct net *net = sock_net(sk);
1168
1169         __build_flow_key(net, &fl4, sk, iph, 0, 0, 0, 0, 0);
1170         rt = __ip_route_output_key(net, &fl4);
1171         if (!IS_ERR(rt)) {
1172                 __ip_do_redirect(rt, skb, &fl4, false);
1173                 ip_rt_put(rt);
1174         }
1175 }
1176 EXPORT_SYMBOL_GPL(ipv4_sk_redirect);
1177
1178 static struct dst_entry *ipv4_dst_check(struct dst_entry *dst, u32 cookie)
1179 {
1180         struct rtable *rt = (struct rtable *) dst;
1181
1182         /* All IPV4 dsts are created with ->obsolete set to the value
1183          * DST_OBSOLETE_FORCE_CHK which forces validation calls down
1184          * into this function always.
1185          *
1186          * When a PMTU/redirect information update invalidates a route,
1187          * this is indicated by setting obsolete to DST_OBSOLETE_KILL or
1188          * DST_OBSOLETE_DEAD.
1189          */
1190         if (dst->obsolete != DST_OBSOLETE_FORCE_CHK || rt_is_expired(rt))
1191                 return NULL;
1192         return dst;
1193 }
1194
1195 static void ipv4_send_dest_unreach(struct sk_buff *skb)
1196 {
1197         struct ip_options opt;
1198         int res;
1199
1200         /* Recompile ip options since IPCB may not be valid anymore.
1201          * Also check we have a reasonable ipv4 header.
1202          */
1203         if (!pskb_network_may_pull(skb, sizeof(struct iphdr)) ||
1204             ip_hdr(skb)->version != 4 || ip_hdr(skb)->ihl < 5)
1205                 return;
1206
1207         memset(&opt, 0, sizeof(opt));
1208         if (ip_hdr(skb)->ihl > 5) {
1209                 if (!pskb_network_may_pull(skb, ip_hdr(skb)->ihl * 4))
1210                         return;
1211                 opt.optlen = ip_hdr(skb)->ihl * 4 - sizeof(struct iphdr);
1212
1213                 rcu_read_lock();
1214                 res = __ip_options_compile(dev_net(skb->dev), &opt, skb, NULL);
1215                 rcu_read_unlock();
1216
1217                 if (res)
1218                         return;
1219         }
1220         __icmp_send(skb, ICMP_DEST_UNREACH, ICMP_HOST_UNREACH, 0, &opt);
1221 }
1222
1223 static void ipv4_link_failure(struct sk_buff *skb)
1224 {
1225         struct rtable *rt;
1226
1227         ipv4_send_dest_unreach(skb);
1228
1229         rt = skb_rtable(skb);
1230         if (rt)
1231                 dst_set_expires(&rt->dst, 0);
1232 }
1233
1234 static int ip_rt_bug(struct net *net, struct sock *sk, struct sk_buff *skb)
1235 {
1236         pr_debug("%s: %pI4 -> %pI4, %s\n",
1237                  __func__, &ip_hdr(skb)->saddr, &ip_hdr(skb)->daddr,
1238                  skb->dev ? skb->dev->name : "?");
1239         kfree_skb(skb);
1240         WARN_ON(1);
1241         return 0;
1242 }
1243
1244 /*
1245    We do not cache source address of outgoing interface,
1246    because it is used only by IP RR, TS and SRR options,
1247    so that it out of fast path.
1248
1249    BTW remember: "addr" is allowed to be not aligned
1250    in IP options!
1251  */
1252
1253 void ip_rt_get_source(u8 *addr, struct sk_buff *skb, struct rtable *rt)
1254 {
1255         __be32 src;
1256
1257         if (rt_is_output_route(rt))
1258                 src = ip_hdr(skb)->saddr;
1259         else {
1260                 struct fib_result res;
1261                 struct iphdr *iph = ip_hdr(skb);
1262                 struct flowi4 fl4 = {
1263                         .daddr = iph->daddr,
1264                         .saddr = iph->saddr,
1265                         .flowi4_tos = RT_TOS(iph->tos),
1266                         .flowi4_oif = rt->dst.dev->ifindex,
1267                         .flowi4_iif = skb->dev->ifindex,
1268                         .flowi4_mark = skb->mark,
1269                 };
1270
1271                 rcu_read_lock();
1272                 if (fib_lookup(dev_net(rt->dst.dev), &fl4, &res, 0) == 0)
1273                         src = fib_result_prefsrc(dev_net(rt->dst.dev), &res);
1274                 else
1275                         src = inet_select_addr(rt->dst.dev,
1276                                                rt_nexthop(rt, iph->daddr),
1277                                                RT_SCOPE_UNIVERSE);
1278                 rcu_read_unlock();
1279         }
1280         memcpy(addr, &src, 4);
1281 }
1282
1283 #ifdef CONFIG_IP_ROUTE_CLASSID
1284 static void set_class_tag(struct rtable *rt, u32 tag)
1285 {
1286         if (!(rt->dst.tclassid & 0xFFFF))
1287                 rt->dst.tclassid |= tag & 0xFFFF;
1288         if (!(rt->dst.tclassid & 0xFFFF0000))
1289                 rt->dst.tclassid |= tag & 0xFFFF0000;
1290 }
1291 #endif
1292
1293 static unsigned int ipv4_default_advmss(const struct dst_entry *dst)
1294 {
1295         unsigned int header_size = sizeof(struct tcphdr) + sizeof(struct iphdr);
1296         unsigned int advmss = max_t(unsigned int, ipv4_mtu(dst) - header_size,
1297                                     ip_rt_min_advmss);
1298
1299         return min(advmss, IPV4_MAX_PMTU - header_size);
1300 }
1301
1302 static unsigned int ipv4_mtu(const struct dst_entry *dst)
1303 {
1304         const struct rtable *rt = (const struct rtable *) dst;
1305         unsigned int mtu = rt->rt_pmtu;
1306
1307         if (!mtu || time_after_eq(jiffies, rt->dst.expires))
1308                 mtu = dst_metric_raw(dst, RTAX_MTU);
1309
1310         if (mtu)
1311                 return mtu;
1312
1313         mtu = READ_ONCE(dst->dev->mtu);
1314
1315         if (unlikely(ip_mtu_locked(dst))) {
1316                 if (rt->rt_uses_gateway && mtu > 576)
1317                         mtu = 576;
1318         }
1319
1320         mtu = min_t(unsigned int, mtu, IP_MAX_MTU);
1321
1322         return mtu - lwtunnel_headroom(dst->lwtstate, mtu);
1323 }
1324
1325 static void ip_del_fnhe(struct fib_nh_common *nhc, __be32 daddr)
1326 {
1327         struct fnhe_hash_bucket *hash;
1328         struct fib_nh_exception *fnhe, __rcu **fnhe_p;
1329         u32 hval = fnhe_hashfun(daddr);
1330
1331         spin_lock_bh(&fnhe_lock);
1332
1333         hash = rcu_dereference_protected(nhc->nhc_exceptions,
1334                                          lockdep_is_held(&fnhe_lock));
1335         hash += hval;
1336
1337         fnhe_p = &hash->chain;
1338         fnhe = rcu_dereference_protected(*fnhe_p, lockdep_is_held(&fnhe_lock));
1339         while (fnhe) {
1340                 if (fnhe->fnhe_daddr == daddr) {
1341                         rcu_assign_pointer(*fnhe_p, rcu_dereference_protected(
1342                                 fnhe->fnhe_next, lockdep_is_held(&fnhe_lock)));
1343                         /* set fnhe_daddr to 0 to ensure it won't bind with
1344                          * new dsts in rt_bind_exception().
1345                          */
1346                         fnhe->fnhe_daddr = 0;
1347                         fnhe_flush_routes(fnhe);
1348                         kfree_rcu(fnhe, rcu);
1349                         break;
1350                 }
1351                 fnhe_p = &fnhe->fnhe_next;
1352                 fnhe = rcu_dereference_protected(fnhe->fnhe_next,
1353                                                  lockdep_is_held(&fnhe_lock));
1354         }
1355
1356         spin_unlock_bh(&fnhe_lock);
1357 }
1358
1359 static struct fib_nh_exception *find_exception(struct fib_nh_common *nhc,
1360                                                __be32 daddr)
1361 {
1362         struct fnhe_hash_bucket *hash = rcu_dereference(nhc->nhc_exceptions);
1363         struct fib_nh_exception *fnhe;
1364         u32 hval;
1365
1366         if (!hash)
1367                 return NULL;
1368
1369         hval = fnhe_hashfun(daddr);
1370
1371         for (fnhe = rcu_dereference(hash[hval].chain); fnhe;
1372              fnhe = rcu_dereference(fnhe->fnhe_next)) {
1373                 if (fnhe->fnhe_daddr == daddr) {
1374                         if (fnhe->fnhe_expires &&
1375                             time_after(jiffies, fnhe->fnhe_expires)) {
1376                                 ip_del_fnhe(nhc, daddr);
1377                                 break;
1378                         }
1379                         return fnhe;
1380                 }
1381         }
1382         return NULL;
1383 }
1384
1385 /* MTU selection:
1386  * 1. mtu on route is locked - use it
1387  * 2. mtu from nexthop exception
1388  * 3. mtu from egress device
1389  */
1390
1391 u32 ip_mtu_from_fib_result(struct fib_result *res, __be32 daddr)
1392 {
1393         struct fib_nh_common *nhc = res->nhc;
1394         struct net_device *dev = nhc->nhc_dev;
1395         struct fib_info *fi = res->fi;
1396         u32 mtu = 0;
1397
1398         if (dev_net(dev)->ipv4.sysctl_ip_fwd_use_pmtu ||
1399             fi->fib_metrics->metrics[RTAX_LOCK - 1] & (1 << RTAX_MTU))
1400                 mtu = fi->fib_mtu;
1401
1402         if (likely(!mtu)) {
1403                 struct fib_nh_exception *fnhe;
1404
1405                 fnhe = find_exception(nhc, daddr);
1406                 if (fnhe && !time_after_eq(jiffies, fnhe->fnhe_expires))
1407                         mtu = fnhe->fnhe_pmtu;
1408         }
1409
1410         if (likely(!mtu))
1411                 mtu = min(READ_ONCE(dev->mtu), IP_MAX_MTU);
1412
1413         return mtu - lwtunnel_headroom(nhc->nhc_lwtstate, mtu);
1414 }
1415
1416 static bool rt_bind_exception(struct rtable *rt, struct fib_nh_exception *fnhe,
1417                               __be32 daddr, const bool do_cache)
1418 {
1419         bool ret = false;
1420
1421         spin_lock_bh(&fnhe_lock);
1422
1423         if (daddr == fnhe->fnhe_daddr) {
1424                 struct rtable __rcu **porig;
1425                 struct rtable *orig;
1426                 int genid = fnhe_genid(dev_net(rt->dst.dev));
1427
1428                 if (rt_is_input_route(rt))
1429                         porig = &fnhe->fnhe_rth_input;
1430                 else
1431                         porig = &fnhe->fnhe_rth_output;
1432                 orig = rcu_dereference(*porig);
1433
1434                 if (fnhe->fnhe_genid != genid) {
1435                         fnhe->fnhe_genid = genid;
1436                         fnhe->fnhe_gw = 0;
1437                         fnhe->fnhe_pmtu = 0;
1438                         fnhe->fnhe_expires = 0;
1439                         fnhe->fnhe_mtu_locked = false;
1440                         fnhe_flush_routes(fnhe);
1441                         orig = NULL;
1442                 }
1443                 fill_route_from_fnhe(rt, fnhe);
1444                 if (!rt->rt_gw4) {
1445                         rt->rt_gw4 = daddr;
1446                         rt->rt_gw_family = AF_INET;
1447                 }
1448
1449                 if (do_cache) {
1450                         dst_hold(&rt->dst);
1451                         rcu_assign_pointer(*porig, rt);
1452                         if (orig) {
1453                                 dst_dev_put(&orig->dst);
1454                                 dst_release(&orig->dst);
1455                         }
1456                         ret = true;
1457                 }
1458
1459                 fnhe->fnhe_stamp = jiffies;
1460         }
1461         spin_unlock_bh(&fnhe_lock);
1462
1463         return ret;
1464 }
1465
1466 static bool rt_cache_route(struct fib_nh_common *nhc, struct rtable *rt)
1467 {
1468         struct rtable *orig, *prev, **p;
1469         bool ret = true;
1470
1471         if (rt_is_input_route(rt)) {
1472                 p = (struct rtable **)&nhc->nhc_rth_input;
1473         } else {
1474                 p = (struct rtable **)raw_cpu_ptr(nhc->nhc_pcpu_rth_output);
1475         }
1476         orig = *p;
1477
1478         /* hold dst before doing cmpxchg() to avoid race condition
1479          * on this dst
1480          */
1481         dst_hold(&rt->dst);
1482         prev = cmpxchg(p, orig, rt);
1483         if (prev == orig) {
1484                 if (orig) {
1485                         rt_add_uncached_list(orig);
1486                         dst_release(&orig->dst);
1487                 }
1488         } else {
1489                 dst_release(&rt->dst);
1490                 ret = false;
1491         }
1492
1493         return ret;
1494 }
1495
1496 struct uncached_list {
1497         spinlock_t              lock;
1498         struct list_head        head;
1499 };
1500
1501 static DEFINE_PER_CPU_ALIGNED(struct uncached_list, rt_uncached_list);
1502
1503 void rt_add_uncached_list(struct rtable *rt)
1504 {
1505         struct uncached_list *ul = raw_cpu_ptr(&rt_uncached_list);
1506
1507         rt->rt_uncached_list = ul;
1508
1509         spin_lock_bh(&ul->lock);
1510         list_add_tail(&rt->rt_uncached, &ul->head);
1511         spin_unlock_bh(&ul->lock);
1512 }
1513
1514 void rt_del_uncached_list(struct rtable *rt)
1515 {
1516         if (!list_empty(&rt->rt_uncached)) {
1517                 struct uncached_list *ul = rt->rt_uncached_list;
1518
1519                 spin_lock_bh(&ul->lock);
1520                 list_del(&rt->rt_uncached);
1521                 spin_unlock_bh(&ul->lock);
1522         }
1523 }
1524
1525 static void ipv4_dst_destroy(struct dst_entry *dst)
1526 {
1527         struct rtable *rt = (struct rtable *)dst;
1528
1529         ip_dst_metrics_put(dst);
1530         rt_del_uncached_list(rt);
1531 }
1532
1533 void rt_flush_dev(struct net_device *dev)
1534 {
1535         struct rtable *rt;
1536         int cpu;
1537
1538         for_each_possible_cpu(cpu) {
1539                 struct uncached_list *ul = &per_cpu(rt_uncached_list, cpu);
1540
1541                 spin_lock_bh(&ul->lock);
1542                 list_for_each_entry(rt, &ul->head, rt_uncached) {
1543                         if (rt->dst.dev != dev)
1544                                 continue;
1545                         rt->dst.dev = blackhole_netdev;
1546                         dev_hold(rt->dst.dev);
1547                         dev_put(dev);
1548                 }
1549                 spin_unlock_bh(&ul->lock);
1550         }
1551 }
1552
1553 static bool rt_cache_valid(const struct rtable *rt)
1554 {
1555         return  rt &&
1556                 rt->dst.obsolete == DST_OBSOLETE_FORCE_CHK &&
1557                 !rt_is_expired(rt);
1558 }
1559
1560 static void rt_set_nexthop(struct rtable *rt, __be32 daddr,
1561                            const struct fib_result *res,
1562                            struct fib_nh_exception *fnhe,
1563                            struct fib_info *fi, u16 type, u32 itag,
1564                            const bool do_cache)
1565 {
1566         bool cached = false;
1567
1568         if (fi) {
1569                 struct fib_nh_common *nhc = FIB_RES_NHC(*res);
1570
1571                 if (nhc->nhc_gw_family && nhc->nhc_scope == RT_SCOPE_LINK) {
1572                         rt->rt_uses_gateway = 1;
1573                         rt->rt_gw_family = nhc->nhc_gw_family;
1574                         /* only INET and INET6 are supported */
1575                         if (likely(nhc->nhc_gw_family == AF_INET))
1576                                 rt->rt_gw4 = nhc->nhc_gw.ipv4;
1577                         else
1578                                 rt->rt_gw6 = nhc->nhc_gw.ipv6;
1579                 }
1580
1581                 ip_dst_init_metrics(&rt->dst, fi->fib_metrics);
1582
1583 #ifdef CONFIG_IP_ROUTE_CLASSID
1584                 if (nhc->nhc_family == AF_INET) {
1585                         struct fib_nh *nh;
1586
1587                         nh = container_of(nhc, struct fib_nh, nh_common);
1588                         rt->dst.tclassid = nh->nh_tclassid;
1589                 }
1590 #endif
1591                 rt->dst.lwtstate = lwtstate_get(nhc->nhc_lwtstate);
1592                 if (unlikely(fnhe))
1593                         cached = rt_bind_exception(rt, fnhe, daddr, do_cache);
1594                 else if (do_cache)
1595                         cached = rt_cache_route(nhc, rt);
1596                 if (unlikely(!cached)) {
1597                         /* Routes we intend to cache in nexthop exception or
1598                          * FIB nexthop have the DST_NOCACHE bit clear.
1599                          * However, if we are unsuccessful at storing this
1600                          * route into the cache we really need to set it.
1601                          */
1602                         if (!rt->rt_gw4) {
1603                                 rt->rt_gw_family = AF_INET;
1604                                 rt->rt_gw4 = daddr;
1605                         }
1606                         rt_add_uncached_list(rt);
1607                 }
1608         } else
1609                 rt_add_uncached_list(rt);
1610
1611 #ifdef CONFIG_IP_ROUTE_CLASSID
1612 #ifdef CONFIG_IP_MULTIPLE_TABLES
1613         set_class_tag(rt, res->tclassid);
1614 #endif
1615         set_class_tag(rt, itag);
1616 #endif
1617 }
1618
1619 struct rtable *rt_dst_alloc(struct net_device *dev,
1620                             unsigned int flags, u16 type,
1621                             bool nopolicy, bool noxfrm, bool will_cache)
1622 {
1623         struct rtable *rt;
1624
1625         rt = dst_alloc(&ipv4_dst_ops, dev, 1, DST_OBSOLETE_FORCE_CHK,
1626                        (will_cache ? 0 : DST_HOST) |
1627                        (nopolicy ? DST_NOPOLICY : 0) |
1628                        (noxfrm ? DST_NOXFRM : 0));
1629
1630         if (rt) {
1631                 rt->rt_genid = rt_genid_ipv4(dev_net(dev));
1632                 rt->rt_flags = flags;
1633                 rt->rt_type = type;
1634                 rt->rt_is_input = 0;
1635                 rt->rt_iif = 0;
1636                 rt->rt_pmtu = 0;
1637                 rt->rt_mtu_locked = 0;
1638                 rt->rt_uses_gateway = 0;
1639                 rt->rt_gw_family = 0;
1640                 rt->rt_gw4 = 0;
1641                 INIT_LIST_HEAD(&rt->rt_uncached);
1642
1643                 rt->dst.output = ip_output;
1644                 if (flags & RTCF_LOCAL)
1645                         rt->dst.input = ip_local_deliver;
1646         }
1647
1648         return rt;
1649 }
1650 EXPORT_SYMBOL(rt_dst_alloc);
1651
1652 struct rtable *rt_dst_clone(struct net_device *dev, struct rtable *rt)
1653 {
1654         struct rtable *new_rt;
1655
1656         new_rt = dst_alloc(&ipv4_dst_ops, dev, 1, DST_OBSOLETE_FORCE_CHK,
1657                            rt->dst.flags);
1658
1659         if (new_rt) {
1660                 new_rt->rt_genid = rt_genid_ipv4(dev_net(dev));
1661                 new_rt->rt_flags = rt->rt_flags;
1662                 new_rt->rt_type = rt->rt_type;
1663                 new_rt->rt_is_input = rt->rt_is_input;
1664                 new_rt->rt_iif = rt->rt_iif;
1665                 new_rt->rt_pmtu = rt->rt_pmtu;
1666                 new_rt->rt_mtu_locked = rt->rt_mtu_locked;
1667                 new_rt->rt_gw_family = rt->rt_gw_family;
1668                 if (rt->rt_gw_family == AF_INET)
1669                         new_rt->rt_gw4 = rt->rt_gw4;
1670                 else if (rt->rt_gw_family == AF_INET6)
1671                         new_rt->rt_gw6 = rt->rt_gw6;
1672                 INIT_LIST_HEAD(&new_rt->rt_uncached);
1673
1674                 new_rt->dst.flags |= DST_HOST;
1675                 new_rt->dst.input = rt->dst.input;
1676                 new_rt->dst.output = rt->dst.output;
1677                 new_rt->dst.error = rt->dst.error;
1678                 new_rt->dst.lastuse = jiffies;
1679                 new_rt->dst.lwtstate = lwtstate_get(rt->dst.lwtstate);
1680         }
1681         return new_rt;
1682 }
1683 EXPORT_SYMBOL(rt_dst_clone);
1684
1685 /* called in rcu_read_lock() section */
1686 int ip_mc_validate_source(struct sk_buff *skb, __be32 daddr, __be32 saddr,
1687                           u8 tos, struct net_device *dev,
1688                           struct in_device *in_dev, u32 *itag)
1689 {
1690         int err;
1691
1692         /* Primary sanity checks. */
1693         if (!in_dev)
1694                 return -EINVAL;
1695
1696         if (ipv4_is_multicast(saddr) || ipv4_is_lbcast(saddr) ||
1697             skb->protocol != htons(ETH_P_IP))
1698                 return -EINVAL;
1699
1700         if (ipv4_is_loopback(saddr) && !IN_DEV_ROUTE_LOCALNET(in_dev))
1701                 return -EINVAL;
1702
1703         if (ipv4_is_zeronet(saddr)) {
1704                 if (!ipv4_is_local_multicast(daddr) &&
1705                     ip_hdr(skb)->protocol != IPPROTO_IGMP)
1706                         return -EINVAL;
1707         } else {
1708                 err = fib_validate_source(skb, saddr, 0, tos, 0, dev,
1709                                           in_dev, itag);
1710                 if (err < 0)
1711                         return err;
1712         }
1713         return 0;
1714 }
1715
1716 /* called in rcu_read_lock() section */
1717 static int ip_route_input_mc(struct sk_buff *skb, __be32 daddr, __be32 saddr,
1718                              u8 tos, struct net_device *dev, int our)
1719 {
1720         struct in_device *in_dev = __in_dev_get_rcu(dev);
1721         unsigned int flags = RTCF_MULTICAST;
1722         struct rtable *rth;
1723         u32 itag = 0;
1724         int err;
1725
1726         err = ip_mc_validate_source(skb, daddr, saddr, tos, dev, in_dev, &itag);
1727         if (err)
1728                 return err;
1729
1730         if (our)
1731                 flags |= RTCF_LOCAL;
1732
1733         rth = rt_dst_alloc(dev_net(dev)->loopback_dev, flags, RTN_MULTICAST,
1734                            IN_DEV_CONF_GET(in_dev, NOPOLICY), false, false);
1735         if (!rth)
1736                 return -ENOBUFS;
1737
1738 #ifdef CONFIG_IP_ROUTE_CLASSID
1739         rth->dst.tclassid = itag;
1740 #endif
1741         rth->dst.output = ip_rt_bug;
1742         rth->rt_is_input= 1;
1743
1744 #ifdef CONFIG_IP_MROUTE
1745         if (!ipv4_is_local_multicast(daddr) && IN_DEV_MFORWARD(in_dev))
1746                 rth->dst.input = ip_mr_input;
1747 #endif
1748         RT_CACHE_STAT_INC(in_slow_mc);
1749
1750         skb_dst_set(skb, &rth->dst);
1751         return 0;
1752 }
1753
1754
1755 static void ip_handle_martian_source(struct net_device *dev,
1756                                      struct in_device *in_dev,
1757                                      struct sk_buff *skb,
1758                                      __be32 daddr,
1759                                      __be32 saddr)
1760 {
1761         RT_CACHE_STAT_INC(in_martian_src);
1762 #ifdef CONFIG_IP_ROUTE_VERBOSE
1763         if (IN_DEV_LOG_MARTIANS(in_dev) && net_ratelimit()) {
1764                 /*
1765                  *      RFC1812 recommendation, if source is martian,
1766                  *      the only hint is MAC header.
1767                  */
1768                 pr_warn("martian source %pI4 from %pI4, on dev %s\n",
1769                         &daddr, &saddr, dev->name);
1770                 if (dev->hard_header_len && skb_mac_header_was_set(skb)) {
1771                         print_hex_dump(KERN_WARNING, "ll header: ",
1772                                        DUMP_PREFIX_OFFSET, 16, 1,
1773                                        skb_mac_header(skb),
1774                                        dev->hard_header_len, false);
1775                 }
1776         }
1777 #endif
1778 }
1779
1780 /* called in rcu_read_lock() section */
1781 static int __mkroute_input(struct sk_buff *skb,
1782                            const struct fib_result *res,
1783                            struct in_device *in_dev,
1784                            __be32 daddr, __be32 saddr, u32 tos)
1785 {
1786         struct fib_nh_common *nhc = FIB_RES_NHC(*res);
1787         struct net_device *dev = nhc->nhc_dev;
1788         struct fib_nh_exception *fnhe;
1789         struct rtable *rth;
1790         int err;
1791         struct in_device *out_dev;
1792         bool do_cache;
1793         u32 itag = 0;
1794
1795         /* get a working reference to the output device */
1796         out_dev = __in_dev_get_rcu(dev);
1797         if (!out_dev) {
1798                 net_crit_ratelimited("Bug in ip_route_input_slow(). Please report.\n");
1799                 return -EINVAL;
1800         }
1801
1802         err = fib_validate_source(skb, saddr, daddr, tos, FIB_RES_OIF(*res),
1803                                   in_dev->dev, in_dev, &itag);
1804         if (err < 0) {
1805                 ip_handle_martian_source(in_dev->dev, in_dev, skb, daddr,
1806                                          saddr);
1807
1808                 goto cleanup;
1809         }
1810
1811         do_cache = res->fi && !itag;
1812         if (out_dev == in_dev && err && IN_DEV_TX_REDIRECTS(out_dev) &&
1813             skb->protocol == htons(ETH_P_IP)) {
1814                 __be32 gw;
1815
1816                 gw = nhc->nhc_gw_family == AF_INET ? nhc->nhc_gw.ipv4 : 0;
1817                 if (IN_DEV_SHARED_MEDIA(out_dev) ||
1818                     inet_addr_onlink(out_dev, saddr, gw))
1819                         IPCB(skb)->flags |= IPSKB_DOREDIRECT;
1820         }
1821
1822         if (skb->protocol != htons(ETH_P_IP)) {
1823                 /* Not IP (i.e. ARP). Do not create route, if it is
1824                  * invalid for proxy arp. DNAT routes are always valid.
1825                  *
1826                  * Proxy arp feature have been extended to allow, ARP
1827                  * replies back to the same interface, to support
1828                  * Private VLAN switch technologies. See arp.c.
1829                  */
1830                 if (out_dev == in_dev &&
1831                     IN_DEV_PROXY_ARP_PVLAN(in_dev) == 0) {
1832                         err = -EINVAL;
1833                         goto cleanup;
1834                 }
1835         }
1836
1837         fnhe = find_exception(nhc, daddr);
1838         if (do_cache) {
1839                 if (fnhe)
1840                         rth = rcu_dereference(fnhe->fnhe_rth_input);
1841                 else
1842                         rth = rcu_dereference(nhc->nhc_rth_input);
1843                 if (rt_cache_valid(rth)) {
1844                         skb_dst_set_noref(skb, &rth->dst);
1845                         goto out;
1846                 }
1847         }
1848
1849         rth = rt_dst_alloc(out_dev->dev, 0, res->type,
1850                            IN_DEV_CONF_GET(in_dev, NOPOLICY),
1851                            IN_DEV_CONF_GET(out_dev, NOXFRM), do_cache);
1852         if (!rth) {
1853                 err = -ENOBUFS;
1854                 goto cleanup;
1855         }
1856
1857         rth->rt_is_input = 1;
1858         RT_CACHE_STAT_INC(in_slow_tot);
1859
1860         rth->dst.input = ip_forward;
1861
1862         rt_set_nexthop(rth, daddr, res, fnhe, res->fi, res->type, itag,
1863                        do_cache);
1864         lwtunnel_set_redirect(&rth->dst);
1865         skb_dst_set(skb, &rth->dst);
1866 out:
1867         err = 0;
1868  cleanup:
1869         return err;
1870 }
1871
1872 #ifdef CONFIG_IP_ROUTE_MULTIPATH
1873 /* To make ICMP packets follow the right flow, the multipath hash is
1874  * calculated from the inner IP addresses.
1875  */
1876 static void ip_multipath_l3_keys(const struct sk_buff *skb,
1877                                  struct flow_keys *hash_keys)
1878 {
1879         const struct iphdr *outer_iph = ip_hdr(skb);
1880         const struct iphdr *key_iph = outer_iph;
1881         const struct iphdr *inner_iph;
1882         const struct icmphdr *icmph;
1883         struct iphdr _inner_iph;
1884         struct icmphdr _icmph;
1885
1886         if (likely(outer_iph->protocol != IPPROTO_ICMP))
1887                 goto out;
1888
1889         if (unlikely((outer_iph->frag_off & htons(IP_OFFSET)) != 0))
1890                 goto out;
1891
1892         icmph = skb_header_pointer(skb, outer_iph->ihl * 4, sizeof(_icmph),
1893                                    &_icmph);
1894         if (!icmph)
1895                 goto out;
1896
1897         if (!icmp_is_err(icmph->type))
1898                 goto out;
1899
1900         inner_iph = skb_header_pointer(skb,
1901                                        outer_iph->ihl * 4 + sizeof(_icmph),
1902                                        sizeof(_inner_iph), &_inner_iph);
1903         if (!inner_iph)
1904                 goto out;
1905
1906         key_iph = inner_iph;
1907 out:
1908         hash_keys->addrs.v4addrs.src = key_iph->saddr;
1909         hash_keys->addrs.v4addrs.dst = key_iph->daddr;
1910 }
1911
1912 /* if skb is set it will be used and fl4 can be NULL */
1913 int fib_multipath_hash(const struct net *net, const struct flowi4 *fl4,
1914                        const struct sk_buff *skb, struct flow_keys *flkeys)
1915 {
1916         u32 multipath_hash = fl4 ? fl4->flowi4_multipath_hash : 0;
1917         struct flow_keys hash_keys;
1918         u32 mhash;
1919
1920         switch (net->ipv4.sysctl_fib_multipath_hash_policy) {
1921         case 0:
1922                 memset(&hash_keys, 0, sizeof(hash_keys));
1923                 hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS;
1924                 if (skb) {
1925                         ip_multipath_l3_keys(skb, &hash_keys);
1926                 } else {
1927                         hash_keys.addrs.v4addrs.src = fl4->saddr;
1928                         hash_keys.addrs.v4addrs.dst = fl4->daddr;
1929                 }
1930                 break;
1931         case 1:
1932                 /* skb is currently provided only when forwarding */
1933                 if (skb) {
1934                         unsigned int flag = FLOW_DISSECTOR_F_STOP_AT_ENCAP;
1935                         struct flow_keys keys;
1936
1937                         /* short-circuit if we already have L4 hash present */
1938                         if (skb->l4_hash)
1939                                 return skb_get_hash_raw(skb) >> 1;
1940
1941                         memset(&hash_keys, 0, sizeof(hash_keys));
1942
1943                         if (!flkeys) {
1944                                 skb_flow_dissect_flow_keys(skb, &keys, flag);
1945                                 flkeys = &keys;
1946                         }
1947
1948                         hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS;
1949                         hash_keys.addrs.v4addrs.src = flkeys->addrs.v4addrs.src;
1950                         hash_keys.addrs.v4addrs.dst = flkeys->addrs.v4addrs.dst;
1951                         hash_keys.ports.src = flkeys->ports.src;
1952                         hash_keys.ports.dst = flkeys->ports.dst;
1953                         hash_keys.basic.ip_proto = flkeys->basic.ip_proto;
1954                 } else {
1955                         memset(&hash_keys, 0, sizeof(hash_keys));
1956                         hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS;
1957                         hash_keys.addrs.v4addrs.src = fl4->saddr;
1958                         hash_keys.addrs.v4addrs.dst = fl4->daddr;
1959                         hash_keys.ports.src = fl4->fl4_sport;
1960                         hash_keys.ports.dst = fl4->fl4_dport;
1961                         hash_keys.basic.ip_proto = fl4->flowi4_proto;
1962                 }
1963                 break;
1964         case 2:
1965                 memset(&hash_keys, 0, sizeof(hash_keys));
1966                 /* skb is currently provided only when forwarding */
1967                 if (skb) {
1968                         struct flow_keys keys;
1969
1970                         skb_flow_dissect_flow_keys(skb, &keys, 0);
1971                         /* Inner can be v4 or v6 */
1972                         if (keys.control.addr_type == FLOW_DISSECTOR_KEY_IPV4_ADDRS) {
1973                                 hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS;
1974                                 hash_keys.addrs.v4addrs.src = keys.addrs.v4addrs.src;
1975                                 hash_keys.addrs.v4addrs.dst = keys.addrs.v4addrs.dst;
1976                         } else if (keys.control.addr_type == FLOW_DISSECTOR_KEY_IPV6_ADDRS) {
1977                                 hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV6_ADDRS;
1978                                 hash_keys.addrs.v6addrs.src = keys.addrs.v6addrs.src;
1979                                 hash_keys.addrs.v6addrs.dst = keys.addrs.v6addrs.dst;
1980                                 hash_keys.tags.flow_label = keys.tags.flow_label;
1981                                 hash_keys.basic.ip_proto = keys.basic.ip_proto;
1982                         } else {
1983                                 /* Same as case 0 */
1984                                 hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS;
1985                                 ip_multipath_l3_keys(skb, &hash_keys);
1986                         }
1987                 } else {
1988                         /* Same as case 0 */
1989                         hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS;
1990                         hash_keys.addrs.v4addrs.src = fl4->saddr;
1991                         hash_keys.addrs.v4addrs.dst = fl4->daddr;
1992                 }
1993                 break;
1994         }
1995         mhash = flow_hash_from_keys(&hash_keys);
1996
1997         if (multipath_hash)
1998                 mhash = jhash_2words(mhash, multipath_hash, 0);
1999
2000         return mhash >> 1;
2001 }
2002 #endif /* CONFIG_IP_ROUTE_MULTIPATH */
2003
2004 static int ip_mkroute_input(struct sk_buff *skb,
2005                             struct fib_result *res,
2006                             struct in_device *in_dev,
2007                             __be32 daddr, __be32 saddr, u32 tos,
2008                             struct flow_keys *hkeys)
2009 {
2010 #ifdef CONFIG_IP_ROUTE_MULTIPATH
2011         if (res->fi && fib_info_num_path(res->fi) > 1) {
2012                 int h = fib_multipath_hash(res->fi->fib_net, NULL, skb, hkeys);
2013
2014                 fib_select_multipath(res, h);
2015         }
2016 #endif
2017
2018         /* create a routing cache entry */
2019         return __mkroute_input(skb, res, in_dev, daddr, saddr, tos);
2020 }
2021
2022 /* Implements all the saddr-related checks as ip_route_input_slow(),
2023  * assuming daddr is valid and the destination is not a local broadcast one.
2024  * Uses the provided hint instead of performing a route lookup.
2025  */
2026 int ip_route_use_hint(struct sk_buff *skb, __be32 daddr, __be32 saddr,
2027                       u8 tos, struct net_device *dev,
2028                       const struct sk_buff *hint)
2029 {
2030         struct in_device *in_dev = __in_dev_get_rcu(dev);
2031         struct rtable *rt = (struct rtable *)hint;
2032         struct net *net = dev_net(dev);
2033         int err = -EINVAL;
2034         u32 tag = 0;
2035
2036         if (ipv4_is_multicast(saddr) || ipv4_is_lbcast(saddr))
2037                 goto martian_source;
2038
2039         if (ipv4_is_zeronet(saddr))
2040                 goto martian_source;
2041
2042         if (ipv4_is_loopback(saddr) && !IN_DEV_NET_ROUTE_LOCALNET(in_dev, net))
2043                 goto martian_source;
2044
2045         if (rt->rt_type != RTN_LOCAL)
2046                 goto skip_validate_source;
2047
2048         tos &= IPTOS_RT_MASK;
2049         err = fib_validate_source(skb, saddr, daddr, tos, 0, dev, in_dev, &tag);
2050         if (err < 0)
2051                 goto martian_source;
2052
2053 skip_validate_source:
2054         skb_dst_copy(skb, hint);
2055         return 0;
2056
2057 martian_source:
2058         ip_handle_martian_source(dev, in_dev, skb, daddr, saddr);
2059         return err;
2060 }
2061
2062 /*
2063  *      NOTE. We drop all the packets that has local source
2064  *      addresses, because every properly looped back packet
2065  *      must have correct destination already attached by output routine.
2066  *      Changes in the enforced policies must be applied also to
2067  *      ip_route_use_hint().
2068  *
2069  *      Such approach solves two big problems:
2070  *      1. Not simplex devices are handled properly.
2071  *      2. IP spoofing attempts are filtered with 100% of guarantee.
2072  *      called with rcu_read_lock()
2073  */
2074
2075 static int ip_route_input_slow(struct sk_buff *skb, __be32 daddr, __be32 saddr,
2076                                u8 tos, struct net_device *dev,
2077                                struct fib_result *res)
2078 {
2079         struct in_device *in_dev = __in_dev_get_rcu(dev);
2080         struct flow_keys *flkeys = NULL, _flkeys;
2081         struct net    *net = dev_net(dev);
2082         struct ip_tunnel_info *tun_info;
2083         int             err = -EINVAL;
2084         unsigned int    flags = 0;
2085         u32             itag = 0;
2086         struct rtable   *rth;
2087         struct flowi4   fl4;
2088         bool do_cache = true;
2089
2090         /* IP on this device is disabled. */
2091
2092         if (!in_dev)
2093                 goto out;
2094
2095         /* Check for the most weird martians, which can be not detected
2096            by fib_lookup.
2097          */
2098
2099         tun_info = skb_tunnel_info(skb);
2100         if (tun_info && !(tun_info->mode & IP_TUNNEL_INFO_TX))
2101                 fl4.flowi4_tun_key.tun_id = tun_info->key.tun_id;
2102         else
2103                 fl4.flowi4_tun_key.tun_id = 0;
2104         skb_dst_drop(skb);
2105
2106         if (ipv4_is_multicast(saddr) || ipv4_is_lbcast(saddr))
2107                 goto martian_source;
2108
2109         res->fi = NULL;
2110         res->table = NULL;
2111         if (ipv4_is_lbcast(daddr) || (saddr == 0 && daddr == 0))
2112                 goto brd_input;
2113
2114         /* Accept zero addresses only to limited broadcast;
2115          * I even do not know to fix it or not. Waiting for complains :-)
2116          */
2117         if (ipv4_is_zeronet(saddr))
2118                 goto martian_source;
2119
2120         if (ipv4_is_zeronet(daddr))
2121                 goto martian_destination;
2122
2123         /* Following code try to avoid calling IN_DEV_NET_ROUTE_LOCALNET(),
2124          * and call it once if daddr or/and saddr are loopback addresses
2125          */
2126         if (ipv4_is_loopback(daddr)) {
2127                 if (!IN_DEV_NET_ROUTE_LOCALNET(in_dev, net))
2128                         goto martian_destination;
2129         } else if (ipv4_is_loopback(saddr)) {
2130                 if (!IN_DEV_NET_ROUTE_LOCALNET(in_dev, net))
2131                         goto martian_source;
2132         }
2133
2134         /*
2135          *      Now we are ready to route packet.
2136          */
2137         fl4.flowi4_oif = 0;
2138         fl4.flowi4_iif = dev->ifindex;
2139         fl4.flowi4_mark = skb->mark;
2140         fl4.flowi4_tos = tos;
2141         fl4.flowi4_scope = RT_SCOPE_UNIVERSE;
2142         fl4.flowi4_flags = 0;
2143         fl4.daddr = daddr;
2144         fl4.saddr = saddr;
2145         fl4.flowi4_uid = sock_net_uid(net, NULL);
2146
2147         if (fib4_rules_early_flow_dissect(net, skb, &fl4, &_flkeys)) {
2148                 flkeys = &_flkeys;
2149         } else {
2150                 fl4.flowi4_proto = 0;
2151                 fl4.fl4_sport = 0;
2152                 fl4.fl4_dport = 0;
2153         }
2154
2155         err = fib_lookup(net, &fl4, res, 0);
2156         if (err != 0) {
2157                 if (!IN_DEV_FORWARD(in_dev))
2158                         err = -EHOSTUNREACH;
2159                 goto no_route;
2160         }
2161
2162         if (res->type == RTN_BROADCAST) {
2163                 if (IN_DEV_BFORWARD(in_dev))
2164                         goto make_route;
2165                 /* not do cache if bc_forwarding is enabled */
2166                 if (IPV4_DEVCONF_ALL(net, BC_FORWARDING))
2167                         do_cache = false;
2168                 goto brd_input;
2169         }
2170
2171         if (res->type == RTN_LOCAL) {
2172                 err = fib_validate_source(skb, saddr, daddr, tos,
2173                                           0, dev, in_dev, &itag);
2174                 if (err < 0)
2175                         goto martian_source;
2176                 goto local_input;
2177         }
2178
2179         if (!IN_DEV_FORWARD(in_dev)) {
2180                 err = -EHOSTUNREACH;
2181                 goto no_route;
2182         }
2183         if (res->type != RTN_UNICAST)
2184                 goto martian_destination;
2185
2186 make_route:
2187         err = ip_mkroute_input(skb, res, in_dev, daddr, saddr, tos, flkeys);
2188 out:    return err;
2189
2190 brd_input:
2191         if (skb->protocol != htons(ETH_P_IP))
2192                 goto e_inval;
2193
2194         if (!ipv4_is_zeronet(saddr)) {
2195                 err = fib_validate_source(skb, saddr, 0, tos, 0, dev,
2196                                           in_dev, &itag);
2197                 if (err < 0)
2198                         goto martian_source;
2199         }
2200         flags |= RTCF_BROADCAST;
2201         res->type = RTN_BROADCAST;
2202         RT_CACHE_STAT_INC(in_brd);
2203
2204 local_input:
2205         do_cache &= res->fi && !itag;
2206         if (do_cache) {
2207                 struct fib_nh_common *nhc = FIB_RES_NHC(*res);
2208
2209                 rth = rcu_dereference(nhc->nhc_rth_input);
2210                 if (rt_cache_valid(rth)) {
2211                         skb_dst_set_noref(skb, &rth->dst);
2212                         err = 0;
2213                         goto out;
2214                 }
2215         }
2216
2217         rth = rt_dst_alloc(l3mdev_master_dev_rcu(dev) ? : net->loopback_dev,
2218                            flags | RTCF_LOCAL, res->type,
2219                            IN_DEV_CONF_GET(in_dev, NOPOLICY), false, do_cache);
2220         if (!rth)
2221                 goto e_nobufs;
2222
2223         rth->dst.output= ip_rt_bug;
2224 #ifdef CONFIG_IP_ROUTE_CLASSID
2225         rth->dst.tclassid = itag;
2226 #endif
2227         rth->rt_is_input = 1;
2228
2229         RT_CACHE_STAT_INC(in_slow_tot);
2230         if (res->type == RTN_UNREACHABLE) {
2231                 rth->dst.input= ip_error;
2232                 rth->dst.error= -err;
2233                 rth->rt_flags   &= ~RTCF_LOCAL;
2234         }
2235
2236         if (do_cache) {
2237                 struct fib_nh_common *nhc = FIB_RES_NHC(*res);
2238
2239                 rth->dst.lwtstate = lwtstate_get(nhc->nhc_lwtstate);
2240                 if (lwtunnel_input_redirect(rth->dst.lwtstate)) {
2241                         WARN_ON(rth->dst.input == lwtunnel_input);
2242                         rth->dst.lwtstate->orig_input = rth->dst.input;
2243                         rth->dst.input = lwtunnel_input;
2244                 }
2245
2246                 if (unlikely(!rt_cache_route(nhc, rth)))
2247                         rt_add_uncached_list(rth);
2248         }
2249         skb_dst_set(skb, &rth->dst);
2250         err = 0;
2251         goto out;
2252
2253 no_route:
2254         RT_CACHE_STAT_INC(in_no_route);
2255         res->type = RTN_UNREACHABLE;
2256         res->fi = NULL;
2257         res->table = NULL;
2258         goto local_input;
2259
2260         /*
2261          *      Do not cache martian addresses: they should be logged (RFC1812)
2262          */
2263 martian_destination:
2264         RT_CACHE_STAT_INC(in_martian_dst);
2265 #ifdef CONFIG_IP_ROUTE_VERBOSE
2266         if (IN_DEV_LOG_MARTIANS(in_dev))
2267                 net_warn_ratelimited("martian destination %pI4 from %pI4, dev %s\n",
2268                                      &daddr, &saddr, dev->name);
2269 #endif
2270
2271 e_inval:
2272         err = -EINVAL;
2273         goto out;
2274
2275 e_nobufs:
2276         err = -ENOBUFS;
2277         goto out;
2278
2279 martian_source:
2280         ip_handle_martian_source(dev, in_dev, skb, daddr, saddr);
2281         goto out;
2282 }
2283
2284 int ip_route_input_noref(struct sk_buff *skb, __be32 daddr, __be32 saddr,
2285                          u8 tos, struct net_device *dev)
2286 {
2287         struct fib_result res;
2288         int err;
2289
2290         tos &= IPTOS_RT_MASK;
2291         rcu_read_lock();
2292         err = ip_route_input_rcu(skb, daddr, saddr, tos, dev, &res);
2293         rcu_read_unlock();
2294
2295         return err;
2296 }
2297 EXPORT_SYMBOL(ip_route_input_noref);
2298
2299 /* called with rcu_read_lock held */
2300 int ip_route_input_rcu(struct sk_buff *skb, __be32 daddr, __be32 saddr,
2301                        u8 tos, struct net_device *dev, struct fib_result *res)
2302 {
2303         /* Multicast recognition logic is moved from route cache to here.
2304            The problem was that too many Ethernet cards have broken/missing
2305            hardware multicast filters :-( As result the host on multicasting
2306            network acquires a lot of useless route cache entries, sort of
2307            SDR messages from all the world. Now we try to get rid of them.
2308            Really, provided software IP multicast filter is organized
2309            reasonably (at least, hashed), it does not result in a slowdown
2310            comparing with route cache reject entries.
2311            Note, that multicast routers are not affected, because
2312            route cache entry is created eventually.
2313          */
2314         if (ipv4_is_multicast(daddr)) {
2315                 struct in_device *in_dev = __in_dev_get_rcu(dev);
2316                 int our = 0;
2317                 int err = -EINVAL;
2318
2319                 if (!in_dev)
2320                         return err;
2321                 our = ip_check_mc_rcu(in_dev, daddr, saddr,
2322                                       ip_hdr(skb)->protocol);
2323
2324                 /* check l3 master if no match yet */
2325                 if (!our && netif_is_l3_slave(dev)) {
2326                         struct in_device *l3_in_dev;
2327
2328                         l3_in_dev = __in_dev_get_rcu(skb->dev);
2329                         if (l3_in_dev)
2330                                 our = ip_check_mc_rcu(l3_in_dev, daddr, saddr,
2331                                                       ip_hdr(skb)->protocol);
2332                 }
2333
2334                 if (our
2335 #ifdef CONFIG_IP_MROUTE
2336                         ||
2337                     (!ipv4_is_local_multicast(daddr) &&
2338                      IN_DEV_MFORWARD(in_dev))
2339 #endif
2340                    ) {
2341                         err = ip_route_input_mc(skb, daddr, saddr,
2342                                                 tos, dev, our);
2343                 }
2344                 return err;
2345         }
2346
2347         return ip_route_input_slow(skb, daddr, saddr, tos, dev, res);
2348 }
2349
2350 /* called with rcu_read_lock() */
2351 static struct rtable *__mkroute_output(const struct fib_result *res,
2352                                        const struct flowi4 *fl4, int orig_oif,
2353                                        struct net_device *dev_out,
2354                                        unsigned int flags)
2355 {
2356         struct fib_info *fi = res->fi;
2357         struct fib_nh_exception *fnhe;
2358         struct in_device *in_dev;
2359         u16 type = res->type;
2360         struct rtable *rth;
2361         bool do_cache;
2362
2363         in_dev = __in_dev_get_rcu(dev_out);
2364         if (!in_dev)
2365                 return ERR_PTR(-EINVAL);
2366
2367         if (likely(!IN_DEV_ROUTE_LOCALNET(in_dev)))
2368                 if (ipv4_is_loopback(fl4->saddr) &&
2369                     !(dev_out->flags & IFF_LOOPBACK) &&
2370                     !netif_is_l3_master(dev_out))
2371                         return ERR_PTR(-EINVAL);
2372
2373         if (ipv4_is_lbcast(fl4->daddr))
2374                 type = RTN_BROADCAST;
2375         else if (ipv4_is_multicast(fl4->daddr))
2376                 type = RTN_MULTICAST;
2377         else if (ipv4_is_zeronet(fl4->daddr))
2378                 return ERR_PTR(-EINVAL);
2379
2380         if (dev_out->flags & IFF_LOOPBACK)
2381                 flags |= RTCF_LOCAL;
2382
2383         do_cache = true;
2384         if (type == RTN_BROADCAST) {
2385                 flags |= RTCF_BROADCAST | RTCF_LOCAL;
2386                 fi = NULL;
2387         } else if (type == RTN_MULTICAST) {
2388                 flags |= RTCF_MULTICAST | RTCF_LOCAL;
2389                 if (!ip_check_mc_rcu(in_dev, fl4->daddr, fl4->saddr,
2390                                      fl4->flowi4_proto))
2391                         flags &= ~RTCF_LOCAL;
2392                 else
2393                         do_cache = false;
2394                 /* If multicast route do not exist use
2395                  * default one, but do not gateway in this case.
2396                  * Yes, it is hack.
2397                  */
2398                 if (fi && res->prefixlen < 4)
2399                         fi = NULL;
2400         } else if ((type == RTN_LOCAL) && (orig_oif != 0) &&
2401                    (orig_oif != dev_out->ifindex)) {
2402                 /* For local routes that require a particular output interface
2403                  * we do not want to cache the result.  Caching the result
2404                  * causes incorrect behaviour when there are multiple source
2405                  * addresses on the interface, the end result being that if the
2406                  * intended recipient is waiting on that interface for the
2407                  * packet he won't receive it because it will be delivered on
2408                  * the loopback interface and the IP_PKTINFO ipi_ifindex will
2409                  * be set to the loopback interface as well.
2410                  */
2411                 do_cache = false;
2412         }
2413
2414         fnhe = NULL;
2415         do_cache &= fi != NULL;
2416         if (fi) {
2417                 struct fib_nh_common *nhc = FIB_RES_NHC(*res);
2418                 struct rtable __rcu **prth;
2419
2420                 fnhe = find_exception(nhc, fl4->daddr);
2421                 if (!do_cache)
2422                         goto add;
2423                 if (fnhe) {
2424                         prth = &fnhe->fnhe_rth_output;
2425                 } else {
2426                         if (unlikely(fl4->flowi4_flags &
2427                                      FLOWI_FLAG_KNOWN_NH &&
2428                                      !(nhc->nhc_gw_family &&
2429                                        nhc->nhc_scope == RT_SCOPE_LINK))) {
2430                                 do_cache = false;
2431                                 goto add;
2432                         }
2433                         prth = raw_cpu_ptr(nhc->nhc_pcpu_rth_output);
2434                 }
2435                 rth = rcu_dereference(*prth);
2436                 if (rt_cache_valid(rth) && dst_hold_safe(&rth->dst))
2437                         return rth;
2438         }
2439
2440 add:
2441         rth = rt_dst_alloc(dev_out, flags, type,
2442                            IN_DEV_CONF_GET(in_dev, NOPOLICY),
2443                            IN_DEV_CONF_GET(in_dev, NOXFRM),
2444                            do_cache);
2445         if (!rth)
2446                 return ERR_PTR(-ENOBUFS);
2447
2448         rth->rt_iif = orig_oif;
2449
2450         RT_CACHE_STAT_INC(out_slow_tot);
2451
2452         if (flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
2453                 if (flags & RTCF_LOCAL &&
2454                     !(dev_out->flags & IFF_LOOPBACK)) {
2455                         rth->dst.output = ip_mc_output;
2456                         RT_CACHE_STAT_INC(out_slow_mc);
2457                 }
2458 #ifdef CONFIG_IP_MROUTE
2459                 if (type == RTN_MULTICAST) {
2460                         if (IN_DEV_MFORWARD(in_dev) &&
2461                             !ipv4_is_local_multicast(fl4->daddr)) {
2462                                 rth->dst.input = ip_mr_input;
2463                                 rth->dst.output = ip_mc_output;
2464                         }
2465                 }
2466 #endif
2467         }
2468
2469         rt_set_nexthop(rth, fl4->daddr, res, fnhe, fi, type, 0, do_cache);
2470         lwtunnel_set_redirect(&rth->dst);
2471
2472         return rth;
2473 }
2474
2475 /*
2476  * Major route resolver routine.
2477  */
2478
2479 struct rtable *ip_route_output_key_hash(struct net *net, struct flowi4 *fl4,
2480                                         const struct sk_buff *skb)
2481 {
2482         __u8 tos = RT_FL_TOS(fl4);
2483         struct fib_result res = {
2484                 .type           = RTN_UNSPEC,
2485                 .fi             = NULL,
2486                 .table          = NULL,
2487                 .tclassid       = 0,
2488         };
2489         struct rtable *rth;
2490
2491         fl4->flowi4_iif = LOOPBACK_IFINDEX;
2492         fl4->flowi4_tos = tos & IPTOS_RT_MASK;
2493         fl4->flowi4_scope = ((tos & RTO_ONLINK) ?
2494                          RT_SCOPE_LINK : RT_SCOPE_UNIVERSE);
2495
2496         rcu_read_lock();
2497         rth = ip_route_output_key_hash_rcu(net, fl4, &res, skb);
2498         rcu_read_unlock();
2499
2500         return rth;
2501 }
2502 EXPORT_SYMBOL_GPL(ip_route_output_key_hash);
2503
2504 struct rtable *ip_route_output_key_hash_rcu(struct net *net, struct flowi4 *fl4,
2505                                             struct fib_result *res,
2506                                             const struct sk_buff *skb)
2507 {
2508         struct net_device *dev_out = NULL;
2509         int orig_oif = fl4->flowi4_oif;
2510         unsigned int flags = 0;
2511         struct rtable *rth;
2512         int err;
2513
2514         if (fl4->saddr) {
2515                 if (ipv4_is_multicast(fl4->saddr) ||
2516                     ipv4_is_lbcast(fl4->saddr) ||
2517                     ipv4_is_zeronet(fl4->saddr)) {
2518                         rth = ERR_PTR(-EINVAL);
2519                         goto out;
2520                 }
2521
2522                 rth = ERR_PTR(-ENETUNREACH);
2523
2524                 /* I removed check for oif == dev_out->oif here.
2525                    It was wrong for two reasons:
2526                    1. ip_dev_find(net, saddr) can return wrong iface, if saddr
2527                       is assigned to multiple interfaces.
2528                    2. Moreover, we are allowed to send packets with saddr
2529                       of another iface. --ANK
2530                  */
2531
2532                 if (fl4->flowi4_oif == 0 &&
2533                     (ipv4_is_multicast(fl4->daddr) ||
2534                      ipv4_is_lbcast(fl4->daddr))) {
2535                         /* It is equivalent to inet_addr_type(saddr) == RTN_LOCAL */
2536                         dev_out = __ip_dev_find(net, fl4->saddr, false);
2537                         if (!dev_out)
2538                                 goto out;
2539
2540                         /* Special hack: user can direct multicasts
2541                            and limited broadcast via necessary interface
2542                            without fiddling with IP_MULTICAST_IF or IP_PKTINFO.
2543                            This hack is not just for fun, it allows
2544                            vic,vat and friends to work.
2545                            They bind socket to loopback, set ttl to zero
2546                            and expect that it will work.
2547                            From the viewpoint of routing cache they are broken,
2548                            because we are not allowed to build multicast path
2549                            with loopback source addr (look, routing cache
2550                            cannot know, that ttl is zero, so that packet
2551                            will not leave this host and route is valid).
2552                            Luckily, this hack is good workaround.
2553                          */
2554
2555                         fl4->flowi4_oif = dev_out->ifindex;
2556                         goto make_route;
2557                 }
2558
2559                 if (!(fl4->flowi4_flags & FLOWI_FLAG_ANYSRC)) {
2560                         /* It is equivalent to inet_addr_type(saddr) == RTN_LOCAL */
2561                         if (!__ip_dev_find(net, fl4->saddr, false))
2562                                 goto out;
2563                 }
2564         }
2565
2566
2567         if (fl4->flowi4_oif) {
2568                 dev_out = dev_get_by_index_rcu(net, fl4->flowi4_oif);
2569                 rth = ERR_PTR(-ENODEV);
2570                 if (!dev_out)
2571                         goto out;
2572
2573                 /* RACE: Check return value of inet_select_addr instead. */
2574                 if (!(dev_out->flags & IFF_UP) || !__in_dev_get_rcu(dev_out)) {
2575                         rth = ERR_PTR(-ENETUNREACH);
2576                         goto out;
2577                 }
2578                 if (ipv4_is_local_multicast(fl4->daddr) ||
2579                     ipv4_is_lbcast(fl4->daddr) ||
2580                     fl4->flowi4_proto == IPPROTO_IGMP) {
2581                         if (!fl4->saddr)
2582                                 fl4->saddr = inet_select_addr(dev_out, 0,
2583                                                               RT_SCOPE_LINK);
2584                         goto make_route;
2585                 }
2586                 if (!fl4->saddr) {
2587                         if (ipv4_is_multicast(fl4->daddr))
2588                                 fl4->saddr = inet_select_addr(dev_out, 0,
2589                                                               fl4->flowi4_scope);
2590                         else if (!fl4->daddr)
2591                                 fl4->saddr = inet_select_addr(dev_out, 0,
2592                                                               RT_SCOPE_HOST);
2593                 }
2594         }
2595
2596         if (!fl4->daddr) {
2597                 fl4->daddr = fl4->saddr;
2598                 if (!fl4->daddr)
2599                         fl4->daddr = fl4->saddr = htonl(INADDR_LOOPBACK);
2600                 dev_out = net->loopback_dev;
2601                 fl4->flowi4_oif = LOOPBACK_IFINDEX;
2602                 res->type = RTN_LOCAL;
2603                 flags |= RTCF_LOCAL;
2604                 goto make_route;
2605         }
2606
2607         err = fib_lookup(net, fl4, res, 0);
2608         if (err) {
2609                 res->fi = NULL;
2610                 res->table = NULL;
2611                 if (fl4->flowi4_oif &&
2612                     (ipv4_is_multicast(fl4->daddr) ||
2613                     !netif_index_is_l3_master(net, fl4->flowi4_oif))) {
2614                         /* Apparently, routing tables are wrong. Assume,
2615                            that the destination is on link.
2616
2617                            WHY? DW.
2618                            Because we are allowed to send to iface
2619                            even if it has NO routes and NO assigned
2620                            addresses. When oif is specified, routing
2621                            tables are looked up with only one purpose:
2622                            to catch if destination is gatewayed, rather than
2623                            direct. Moreover, if MSG_DONTROUTE is set,
2624                            we send packet, ignoring both routing tables
2625                            and ifaddr state. --ANK
2626
2627
2628                            We could make it even if oif is unknown,
2629                            likely IPv6, but we do not.
2630                          */
2631
2632                         if (fl4->saddr == 0)
2633                                 fl4->saddr = inet_select_addr(dev_out, 0,
2634                                                               RT_SCOPE_LINK);
2635                         res->type = RTN_UNICAST;
2636                         goto make_route;
2637                 }
2638                 rth = ERR_PTR(err);
2639                 goto out;
2640         }
2641
2642         if (res->type == RTN_LOCAL) {
2643                 if (!fl4->saddr) {
2644                         if (res->fi->fib_prefsrc)
2645                                 fl4->saddr = res->fi->fib_prefsrc;
2646                         else
2647                                 fl4->saddr = fl4->daddr;
2648                 }
2649
2650                 /* L3 master device is the loopback for that domain */
2651                 dev_out = l3mdev_master_dev_rcu(FIB_RES_DEV(*res)) ? :
2652                         net->loopback_dev;
2653
2654                 /* make sure orig_oif points to fib result device even
2655                  * though packet rx/tx happens over loopback or l3mdev
2656                  */
2657                 orig_oif = FIB_RES_OIF(*res);
2658
2659                 fl4->flowi4_oif = dev_out->ifindex;
2660                 flags |= RTCF_LOCAL;
2661                 goto make_route;
2662         }
2663
2664         fib_select_path(net, res, fl4, skb);
2665
2666         dev_out = FIB_RES_DEV(*res);
2667         fl4->flowi4_oif = dev_out->ifindex;
2668
2669
2670 make_route:
2671         rth = __mkroute_output(res, fl4, orig_oif, dev_out, flags);
2672
2673 out:
2674         return rth;
2675 }
2676
2677 static struct dst_entry *ipv4_blackhole_dst_check(struct dst_entry *dst, u32 cookie)
2678 {
2679         return NULL;
2680 }
2681
2682 static unsigned int ipv4_blackhole_mtu(const struct dst_entry *dst)
2683 {
2684         unsigned int mtu = dst_metric_raw(dst, RTAX_MTU);
2685
2686         return mtu ? : dst->dev->mtu;
2687 }
2688
2689 static void ipv4_rt_blackhole_update_pmtu(struct dst_entry *dst, struct sock *sk,
2690                                           struct sk_buff *skb, u32 mtu)
2691 {
2692 }
2693
2694 static void ipv4_rt_blackhole_redirect(struct dst_entry *dst, struct sock *sk,
2695                                        struct sk_buff *skb)
2696 {
2697 }
2698
2699 static u32 *ipv4_rt_blackhole_cow_metrics(struct dst_entry *dst,
2700                                           unsigned long old)
2701 {
2702         return NULL;
2703 }
2704
2705 static struct dst_ops ipv4_dst_blackhole_ops = {
2706         .family                 =       AF_INET,
2707         .check                  =       ipv4_blackhole_dst_check,
2708         .mtu                    =       ipv4_blackhole_mtu,
2709         .default_advmss         =       ipv4_default_advmss,
2710         .update_pmtu            =       ipv4_rt_blackhole_update_pmtu,
2711         .redirect               =       ipv4_rt_blackhole_redirect,
2712         .cow_metrics            =       ipv4_rt_blackhole_cow_metrics,
2713         .neigh_lookup           =       ipv4_neigh_lookup,
2714 };
2715
2716 struct dst_entry *ipv4_blackhole_route(struct net *net, struct dst_entry *dst_orig)
2717 {
2718         struct rtable *ort = (struct rtable *) dst_orig;
2719         struct rtable *rt;
2720
2721         rt = dst_alloc(&ipv4_dst_blackhole_ops, NULL, 1, DST_OBSOLETE_DEAD, 0);
2722         if (rt) {
2723                 struct dst_entry *new = &rt->dst;
2724
2725                 new->__use = 1;
2726                 new->input = dst_discard;
2727                 new->output = dst_discard_out;
2728
2729                 new->dev = net->loopback_dev;
2730                 if (new->dev)
2731                         dev_hold(new->dev);
2732
2733                 rt->rt_is_input = ort->rt_is_input;
2734                 rt->rt_iif = ort->rt_iif;
2735                 rt->rt_pmtu = ort->rt_pmtu;
2736                 rt->rt_mtu_locked = ort->rt_mtu_locked;
2737
2738                 rt->rt_genid = rt_genid_ipv4(net);
2739                 rt->rt_flags = ort->rt_flags;
2740                 rt->rt_type = ort->rt_type;
2741                 rt->rt_uses_gateway = ort->rt_uses_gateway;
2742                 rt->rt_gw_family = ort->rt_gw_family;
2743                 if (rt->rt_gw_family == AF_INET)
2744                         rt->rt_gw4 = ort->rt_gw4;
2745                 else if (rt->rt_gw_family == AF_INET6)
2746                         rt->rt_gw6 = ort->rt_gw6;
2747
2748                 INIT_LIST_HEAD(&rt->rt_uncached);
2749         }
2750
2751         dst_release(dst_orig);
2752
2753         return rt ? &rt->dst : ERR_PTR(-ENOMEM);
2754 }
2755
2756 struct rtable *ip_route_output_flow(struct net *net, struct flowi4 *flp4,
2757                                     const struct sock *sk)
2758 {
2759         struct rtable *rt = __ip_route_output_key(net, flp4);
2760
2761         if (IS_ERR(rt))
2762                 return rt;
2763
2764         if (flp4->flowi4_proto)
2765                 rt = (struct rtable *)xfrm_lookup_route(net, &rt->dst,
2766                                                         flowi4_to_flowi(flp4),
2767                                                         sk, 0);
2768
2769         return rt;
2770 }
2771 EXPORT_SYMBOL_GPL(ip_route_output_flow);
2772
2773 /* called with rcu_read_lock held */
2774 static int rt_fill_info(struct net *net, __be32 dst, __be32 src,
2775                         struct rtable *rt, u32 table_id, struct flowi4 *fl4,
2776                         struct sk_buff *skb, u32 portid, u32 seq,
2777                         unsigned int flags)
2778 {
2779         struct rtmsg *r;
2780         struct nlmsghdr *nlh;
2781         unsigned long expires = 0;
2782         u32 error;
2783         u32 metrics[RTAX_MAX];
2784
2785         nlh = nlmsg_put(skb, portid, seq, RTM_NEWROUTE, sizeof(*r), flags);
2786         if (!nlh)
2787                 return -EMSGSIZE;
2788
2789         r = nlmsg_data(nlh);
2790         r->rtm_family    = AF_INET;
2791         r->rtm_dst_len  = 32;
2792         r->rtm_src_len  = 0;
2793         r->rtm_tos      = fl4 ? fl4->flowi4_tos : 0;
2794         r->rtm_table    = table_id < 256 ? table_id : RT_TABLE_COMPAT;
2795         if (nla_put_u32(skb, RTA_TABLE, table_id))
2796                 goto nla_put_failure;
2797         r->rtm_type     = rt->rt_type;
2798         r->rtm_scope    = RT_SCOPE_UNIVERSE;
2799         r->rtm_protocol = RTPROT_UNSPEC;
2800         r->rtm_flags    = (rt->rt_flags & ~0xFFFF) | RTM_F_CLONED;
2801         if (rt->rt_flags & RTCF_NOTIFY)
2802                 r->rtm_flags |= RTM_F_NOTIFY;
2803         if (IPCB(skb)->flags & IPSKB_DOREDIRECT)
2804                 r->rtm_flags |= RTCF_DOREDIRECT;
2805
2806         if (nla_put_in_addr(skb, RTA_DST, dst))
2807                 goto nla_put_failure;
2808         if (src) {
2809                 r->rtm_src_len = 32;
2810                 if (nla_put_in_addr(skb, RTA_SRC, src))
2811                         goto nla_put_failure;
2812         }
2813         if (rt->dst.dev &&
2814             nla_put_u32(skb, RTA_OIF, rt->dst.dev->ifindex))
2815                 goto nla_put_failure;
2816 #ifdef CONFIG_IP_ROUTE_CLASSID
2817         if (rt->dst.tclassid &&
2818             nla_put_u32(skb, RTA_FLOW, rt->dst.tclassid))
2819                 goto nla_put_failure;
2820 #endif
2821         if (fl4 && !rt_is_input_route(rt) &&
2822             fl4->saddr != src) {
2823                 if (nla_put_in_addr(skb, RTA_PREFSRC, fl4->saddr))
2824                         goto nla_put_failure;
2825         }
2826         if (rt->rt_uses_gateway) {
2827                 if (rt->rt_gw_family == AF_INET &&
2828                     nla_put_in_addr(skb, RTA_GATEWAY, rt->rt_gw4)) {
2829                         goto nla_put_failure;
2830                 } else if (rt->rt_gw_family == AF_INET6) {
2831                         int alen = sizeof(struct in6_addr);
2832                         struct nlattr *nla;
2833                         struct rtvia *via;
2834
2835                         nla = nla_reserve(skb, RTA_VIA, alen + 2);
2836                         if (!nla)
2837                                 goto nla_put_failure;
2838
2839                         via = nla_data(nla);
2840                         via->rtvia_family = AF_INET6;
2841                         memcpy(via->rtvia_addr, &rt->rt_gw6, alen);
2842                 }
2843         }
2844
2845         expires = rt->dst.expires;
2846         if (expires) {
2847                 unsigned long now = jiffies;
2848
2849                 if (time_before(now, expires))
2850                         expires -= now;
2851                 else
2852                         expires = 0;
2853         }
2854
2855         memcpy(metrics, dst_metrics_ptr(&rt->dst), sizeof(metrics));
2856         if (rt->rt_pmtu && expires)
2857                 metrics[RTAX_MTU - 1] = rt->rt_pmtu;
2858         if (rt->rt_mtu_locked && expires)
2859                 metrics[RTAX_LOCK - 1] |= BIT(RTAX_MTU);
2860         if (rtnetlink_put_metrics(skb, metrics) < 0)
2861                 goto nla_put_failure;
2862
2863         if (fl4) {
2864                 if (fl4->flowi4_mark &&
2865                     nla_put_u32(skb, RTA_MARK, fl4->flowi4_mark))
2866                         goto nla_put_failure;
2867
2868                 if (!uid_eq(fl4->flowi4_uid, INVALID_UID) &&
2869                     nla_put_u32(skb, RTA_UID,
2870                                 from_kuid_munged(current_user_ns(),
2871                                                  fl4->flowi4_uid)))
2872                         goto nla_put_failure;
2873
2874                 if (rt_is_input_route(rt)) {
2875 #ifdef CONFIG_IP_MROUTE
2876                         if (ipv4_is_multicast(dst) &&
2877                             !ipv4_is_local_multicast(dst) &&
2878                             IPV4_DEVCONF_ALL(net, MC_FORWARDING)) {
2879                                 int err = ipmr_get_route(net, skb,
2880                                                          fl4->saddr, fl4->daddr,
2881                                                          r, portid);
2882
2883                                 if (err <= 0) {
2884                                         if (err == 0)
2885                                                 return 0;
2886                                         goto nla_put_failure;
2887                                 }
2888                         } else
2889 #endif
2890                                 if (nla_put_u32(skb, RTA_IIF, fl4->flowi4_iif))
2891                                         goto nla_put_failure;
2892                 }
2893         }
2894
2895         error = rt->dst.error;
2896
2897         if (rtnl_put_cacheinfo(skb, &rt->dst, 0, expires, error) < 0)
2898                 goto nla_put_failure;
2899
2900         nlmsg_end(skb, nlh);
2901         return 0;
2902
2903 nla_put_failure:
2904         nlmsg_cancel(skb, nlh);
2905         return -EMSGSIZE;
2906 }
2907
2908 static int fnhe_dump_bucket(struct net *net, struct sk_buff *skb,
2909                             struct netlink_callback *cb, u32 table_id,
2910                             struct fnhe_hash_bucket *bucket, int genid,
2911                             int *fa_index, int fa_start, unsigned int flags)
2912 {
2913         int i;
2914
2915         for (i = 0; i < FNHE_HASH_SIZE; i++) {
2916                 struct fib_nh_exception *fnhe;
2917
2918                 for (fnhe = rcu_dereference(bucket[i].chain); fnhe;
2919                      fnhe = rcu_dereference(fnhe->fnhe_next)) {
2920                         struct rtable *rt;
2921                         int err;
2922
2923                         if (*fa_index < fa_start)
2924                                 goto next;
2925
2926                         if (fnhe->fnhe_genid != genid)
2927                                 goto next;
2928
2929                         if (fnhe->fnhe_expires &&
2930                             time_after(jiffies, fnhe->fnhe_expires))
2931                                 goto next;
2932
2933                         rt = rcu_dereference(fnhe->fnhe_rth_input);
2934                         if (!rt)
2935                                 rt = rcu_dereference(fnhe->fnhe_rth_output);
2936                         if (!rt)
2937                                 goto next;
2938
2939                         err = rt_fill_info(net, fnhe->fnhe_daddr, 0, rt,
2940                                            table_id, NULL, skb,
2941                                            NETLINK_CB(cb->skb).portid,
2942                                            cb->nlh->nlmsg_seq, flags);
2943                         if (err)
2944                                 return err;
2945 next:
2946                         (*fa_index)++;
2947                 }
2948         }
2949
2950         return 0;
2951 }
2952
2953 int fib_dump_info_fnhe(struct sk_buff *skb, struct netlink_callback *cb,
2954                        u32 table_id, struct fib_info *fi,
2955                        int *fa_index, int fa_start, unsigned int flags)
2956 {
2957         struct net *net = sock_net(cb->skb->sk);
2958         int nhsel, genid = fnhe_genid(net);
2959
2960         for (nhsel = 0; nhsel < fib_info_num_path(fi); nhsel++) {
2961                 struct fib_nh_common *nhc = fib_info_nhc(fi, nhsel);
2962                 struct fnhe_hash_bucket *bucket;
2963                 int err;
2964
2965                 if (nhc->nhc_flags & RTNH_F_DEAD)
2966                         continue;
2967
2968                 rcu_read_lock();
2969                 bucket = rcu_dereference(nhc->nhc_exceptions);
2970                 err = 0;
2971                 if (bucket)
2972                         err = fnhe_dump_bucket(net, skb, cb, table_id, bucket,
2973                                                genid, fa_index, fa_start,
2974                                                flags);
2975                 rcu_read_unlock();
2976                 if (err)
2977                         return err;
2978         }
2979
2980         return 0;
2981 }
2982
2983 static struct sk_buff *inet_rtm_getroute_build_skb(__be32 src, __be32 dst,
2984                                                    u8 ip_proto, __be16 sport,
2985                                                    __be16 dport)
2986 {
2987         struct sk_buff *skb;
2988         struct iphdr *iph;
2989
2990         skb = alloc_skb(NLMSG_GOODSIZE, GFP_KERNEL);
2991         if (!skb)
2992                 return NULL;
2993
2994         /* Reserve room for dummy headers, this skb can pass
2995          * through good chunk of routing engine.
2996          */
2997         skb_reset_mac_header(skb);
2998         skb_reset_network_header(skb);
2999         skb->protocol = htons(ETH_P_IP);
3000         iph = skb_put(skb, sizeof(struct iphdr));
3001         iph->protocol = ip_proto;
3002         iph->saddr = src;
3003         iph->daddr = dst;
3004         iph->version = 0x4;
3005         iph->frag_off = 0;
3006         iph->ihl = 0x5;
3007         skb_set_transport_header(skb, skb->len);
3008
3009         switch (iph->protocol) {
3010         case IPPROTO_UDP: {
3011                 struct udphdr *udph;
3012
3013                 udph = skb_put_zero(skb, sizeof(struct udphdr));
3014                 udph->source = sport;
3015                 udph->dest = dport;
3016                 udph->len = sizeof(struct udphdr);
3017                 udph->check = 0;
3018                 break;
3019         }
3020         case IPPROTO_TCP: {
3021                 struct tcphdr *tcph;
3022
3023                 tcph = skb_put_zero(skb, sizeof(struct tcphdr));
3024                 tcph->source    = sport;
3025                 tcph->dest      = dport;
3026                 tcph->doff      = sizeof(struct tcphdr) / 4;
3027                 tcph->rst = 1;
3028                 tcph->check = ~tcp_v4_check(sizeof(struct tcphdr),
3029                                             src, dst, 0);
3030                 break;
3031         }
3032         case IPPROTO_ICMP: {
3033                 struct icmphdr *icmph;
3034
3035                 icmph = skb_put_zero(skb, sizeof(struct icmphdr));
3036                 icmph->type = ICMP_ECHO;
3037                 icmph->code = 0;
3038         }
3039         }
3040
3041         return skb;
3042 }
3043
3044 static int inet_rtm_valid_getroute_req(struct sk_buff *skb,
3045                                        const struct nlmsghdr *nlh,
3046                                        struct nlattr **tb,
3047                                        struct netlink_ext_ack *extack)
3048 {
3049         struct rtmsg *rtm;
3050         int i, err;
3051
3052         if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*rtm))) {
3053                 NL_SET_ERR_MSG(extack,
3054                                "ipv4: Invalid header for route get request");
3055                 return -EINVAL;
3056         }
3057
3058         if (!netlink_strict_get_check(skb))
3059                 return nlmsg_parse_deprecated(nlh, sizeof(*rtm), tb, RTA_MAX,
3060                                               rtm_ipv4_policy, extack);
3061
3062         rtm = nlmsg_data(nlh);
3063         if ((rtm->rtm_src_len && rtm->rtm_src_len != 32) ||
3064             (rtm->rtm_dst_len && rtm->rtm_dst_len != 32) ||
3065             rtm->rtm_table || rtm->rtm_protocol ||
3066             rtm->rtm_scope || rtm->rtm_type) {
3067                 NL_SET_ERR_MSG(extack, "ipv4: Invalid values in header for route get request");
3068                 return -EINVAL;
3069         }
3070
3071         if (rtm->rtm_flags & ~(RTM_F_NOTIFY |
3072                                RTM_F_LOOKUP_TABLE |
3073                                RTM_F_FIB_MATCH)) {
3074                 NL_SET_ERR_MSG(extack, "ipv4: Unsupported rtm_flags for route get request");
3075                 return -EINVAL;
3076         }
3077
3078         err = nlmsg_parse_deprecated_strict(nlh, sizeof(*rtm), tb, RTA_MAX,
3079                                             rtm_ipv4_policy, extack);
3080         if (err)
3081                 return err;
3082
3083         if ((tb[RTA_SRC] && !rtm->rtm_src_len) ||
3084             (tb[RTA_DST] && !rtm->rtm_dst_len)) {
3085                 NL_SET_ERR_MSG(extack, "ipv4: rtm_src_len and rtm_dst_len must be 32 for IPv4");
3086                 return -EINVAL;
3087         }
3088
3089         for (i = 0; i <= RTA_MAX; i++) {
3090                 if (!tb[i])
3091                         continue;
3092
3093                 switch (i) {
3094                 case RTA_IIF:
3095                 case RTA_OIF:
3096                 case RTA_SRC:
3097                 case RTA_DST:
3098                 case RTA_IP_PROTO:
3099                 case RTA_SPORT:
3100                 case RTA_DPORT:
3101                 case RTA_MARK:
3102                 case RTA_UID:
3103                         break;
3104                 default:
3105                         NL_SET_ERR_MSG(extack, "ipv4: Unsupported attribute in route get request");
3106                         return -EINVAL;
3107                 }
3108         }
3109
3110         return 0;
3111 }
3112
3113 static int inet_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh,
3114                              struct netlink_ext_ack *extack)
3115 {
3116         struct net *net = sock_net(in_skb->sk);
3117         struct nlattr *tb[RTA_MAX+1];
3118         u32 table_id = RT_TABLE_MAIN;
3119         __be16 sport = 0, dport = 0;
3120         struct fib_result res = {};
3121         u8 ip_proto = IPPROTO_UDP;
3122         struct rtable *rt = NULL;
3123         struct sk_buff *skb;
3124         struct rtmsg *rtm;
3125         struct flowi4 fl4 = {};
3126         __be32 dst = 0;
3127         __be32 src = 0;
3128         kuid_t uid;
3129         u32 iif;
3130         int err;
3131         int mark;
3132
3133         err = inet_rtm_valid_getroute_req(in_skb, nlh, tb, extack);
3134         if (err < 0)
3135                 return err;
3136
3137         rtm = nlmsg_data(nlh);
3138         src = tb[RTA_SRC] ? nla_get_in_addr(tb[RTA_SRC]) : 0;
3139         dst = tb[RTA_DST] ? nla_get_in_addr(tb[RTA_DST]) : 0;
3140         iif = tb[RTA_IIF] ? nla_get_u32(tb[RTA_IIF]) : 0;
3141         mark = tb[RTA_MARK] ? nla_get_u32(tb[RTA_MARK]) : 0;
3142         if (tb[RTA_UID])
3143                 uid = make_kuid(current_user_ns(), nla_get_u32(tb[RTA_UID]));
3144         else
3145                 uid = (iif ? INVALID_UID : current_uid());
3146
3147         if (tb[RTA_IP_PROTO]) {
3148                 err = rtm_getroute_parse_ip_proto(tb[RTA_IP_PROTO],
3149                                                   &ip_proto, AF_INET, extack);
3150                 if (err)
3151                         return err;
3152         }
3153
3154         if (tb[RTA_SPORT])
3155                 sport = nla_get_be16(tb[RTA_SPORT]);
3156
3157         if (tb[RTA_DPORT])
3158                 dport = nla_get_be16(tb[RTA_DPORT]);
3159
3160         skb = inet_rtm_getroute_build_skb(src, dst, ip_proto, sport, dport);
3161         if (!skb)
3162                 return -ENOBUFS;
3163
3164         fl4.daddr = dst;
3165         fl4.saddr = src;
3166         fl4.flowi4_tos = rtm->rtm_tos;
3167         fl4.flowi4_oif = tb[RTA_OIF] ? nla_get_u32(tb[RTA_OIF]) : 0;
3168         fl4.flowi4_mark = mark;
3169         fl4.flowi4_uid = uid;
3170         if (sport)
3171                 fl4.fl4_sport = sport;
3172         if (dport)
3173                 fl4.fl4_dport = dport;
3174         fl4.flowi4_proto = ip_proto;
3175
3176         rcu_read_lock();
3177
3178         if (iif) {
3179                 struct net_device *dev;
3180
3181                 dev = dev_get_by_index_rcu(net, iif);
3182                 if (!dev) {
3183                         err = -ENODEV;
3184                         goto errout_rcu;
3185                 }
3186
3187                 fl4.flowi4_iif = iif; /* for rt_fill_info */
3188                 skb->dev        = dev;
3189                 skb->mark       = mark;
3190                 err = ip_route_input_rcu(skb, dst, src, rtm->rtm_tos,
3191                                          dev, &res);
3192
3193                 rt = skb_rtable(skb);
3194                 if (err == 0 && rt->dst.error)
3195                         err = -rt->dst.error;
3196         } else {
3197                 fl4.flowi4_iif = LOOPBACK_IFINDEX;
3198                 skb->dev = net->loopback_dev;
3199                 rt = ip_route_output_key_hash_rcu(net, &fl4, &res, skb);
3200                 err = 0;
3201                 if (IS_ERR(rt))
3202                         err = PTR_ERR(rt);
3203                 else
3204                         skb_dst_set(skb, &rt->dst);
3205         }
3206
3207         if (err)
3208                 goto errout_rcu;
3209
3210         if (rtm->rtm_flags & RTM_F_NOTIFY)
3211                 rt->rt_flags |= RTCF_NOTIFY;
3212
3213         if (rtm->rtm_flags & RTM_F_LOOKUP_TABLE)
3214                 table_id = res.table ? res.table->tb_id : 0;
3215
3216         /* reset skb for netlink reply msg */
3217         skb_trim(skb, 0);
3218         skb_reset_network_header(skb);
3219         skb_reset_transport_header(skb);
3220         skb_reset_mac_header(skb);
3221
3222         if (rtm->rtm_flags & RTM_F_FIB_MATCH) {
3223                 if (!res.fi) {
3224                         err = fib_props[res.type].error;
3225                         if (!err)
3226                                 err = -EHOSTUNREACH;
3227                         goto errout_rcu;
3228                 }
3229                 err = fib_dump_info(skb, NETLINK_CB(in_skb).portid,
3230                                     nlh->nlmsg_seq, RTM_NEWROUTE, table_id,
3231                                     rt->rt_type, res.prefix, res.prefixlen,
3232                                     fl4.flowi4_tos, res.fi, 0);
3233         } else {
3234                 err = rt_fill_info(net, dst, src, rt, table_id, &fl4, skb,
3235                                    NETLINK_CB(in_skb).portid,
3236                                    nlh->nlmsg_seq, 0);
3237         }
3238         if (err < 0)
3239                 goto errout_rcu;
3240
3241         rcu_read_unlock();
3242
3243         err = rtnl_unicast(skb, net, NETLINK_CB(in_skb).portid);
3244
3245 errout_free:
3246         return err;
3247 errout_rcu:
3248         rcu_read_unlock();
3249         kfree_skb(skb);
3250         goto errout_free;
3251 }
3252
3253 void ip_rt_multicast_event(struct in_device *in_dev)
3254 {
3255         rt_cache_flush(dev_net(in_dev->dev));
3256 }
3257
3258 #ifdef CONFIG_SYSCTL
3259 static int ip_rt_gc_interval __read_mostly  = 60 * HZ;
3260 static int ip_rt_gc_min_interval __read_mostly  = HZ / 2;
3261 static int ip_rt_gc_elasticity __read_mostly    = 8;
3262 static int ip_min_valid_pmtu __read_mostly      = IPV4_MIN_MTU;
3263
3264 static int ipv4_sysctl_rtcache_flush(struct ctl_table *__ctl, int write,
3265                                         void __user *buffer,
3266                                         size_t *lenp, loff_t *ppos)
3267 {
3268         struct net *net = (struct net *)__ctl->extra1;
3269
3270         if (write) {
3271                 rt_cache_flush(net);
3272                 fnhe_genid_bump(net);
3273                 return 0;
3274         }
3275
3276         return -EINVAL;
3277 }
3278
3279 static struct ctl_table ipv4_route_table[] = {
3280         {
3281                 .procname       = "gc_thresh",
3282                 .data           = &ipv4_dst_ops.gc_thresh,
3283                 .maxlen         = sizeof(int),
3284                 .mode           = 0644,
3285                 .proc_handler   = proc_dointvec,
3286         },
3287         {
3288                 .procname       = "max_size",
3289                 .data           = &ip_rt_max_size,
3290                 .maxlen         = sizeof(int),
3291                 .mode           = 0644,
3292                 .proc_handler   = proc_dointvec,
3293         },
3294         {
3295                 /*  Deprecated. Use gc_min_interval_ms */
3296
3297                 .procname       = "gc_min_interval",
3298                 .data           = &ip_rt_gc_min_interval,
3299                 .maxlen         = sizeof(int),
3300                 .mode           = 0644,
3301                 .proc_handler   = proc_dointvec_jiffies,
3302         },
3303         {
3304                 .procname       = "gc_min_interval_ms",
3305                 .data           = &ip_rt_gc_min_interval,
3306                 .maxlen         = sizeof(int),
3307                 .mode           = 0644,
3308                 .proc_handler   = proc_dointvec_ms_jiffies,
3309         },
3310         {
3311                 .procname       = "gc_timeout",
3312                 .data           = &ip_rt_gc_timeout,
3313                 .maxlen         = sizeof(int),
3314                 .mode           = 0644,
3315                 .proc_handler   = proc_dointvec_jiffies,
3316         },
3317         {
3318                 .procname       = "gc_interval",
3319                 .data           = &ip_rt_gc_interval,
3320                 .maxlen         = sizeof(int),
3321                 .mode           = 0644,
3322                 .proc_handler   = proc_dointvec_jiffies,
3323         },
3324         {
3325                 .procname       = "redirect_load",
3326                 .data           = &ip_rt_redirect_load,
3327                 .maxlen         = sizeof(int),
3328                 .mode           = 0644,
3329                 .proc_handler   = proc_dointvec,
3330         },
3331         {
3332                 .procname       = "redirect_number",
3333                 .data           = &ip_rt_redirect_number,
3334                 .maxlen         = sizeof(int),
3335                 .mode           = 0644,
3336                 .proc_handler   = proc_dointvec,
3337         },
3338         {
3339                 .procname       = "redirect_silence",
3340                 .data           = &ip_rt_redirect_silence,
3341                 .maxlen         = sizeof(int),
3342                 .mode           = 0644,
3343                 .proc_handler   = proc_dointvec,
3344         },
3345         {
3346                 .procname       = "error_cost",
3347                 .data           = &ip_rt_error_cost,
3348                 .maxlen         = sizeof(int),
3349                 .mode           = 0644,
3350                 .proc_handler   = proc_dointvec,
3351         },
3352         {
3353                 .procname       = "error_burst",
3354                 .data           = &ip_rt_error_burst,
3355                 .maxlen         = sizeof(int),
3356                 .mode           = 0644,
3357                 .proc_handler   = proc_dointvec,
3358         },
3359         {
3360                 .procname       = "gc_elasticity",
3361                 .data           = &ip_rt_gc_elasticity,
3362                 .maxlen         = sizeof(int),
3363                 .mode           = 0644,
3364                 .proc_handler   = proc_dointvec,
3365         },
3366         {
3367                 .procname       = "mtu_expires",
3368                 .data           = &ip_rt_mtu_expires,
3369                 .maxlen         = sizeof(int),
3370                 .mode           = 0644,
3371                 .proc_handler   = proc_dointvec_jiffies,
3372         },
3373         {
3374                 .procname       = "min_pmtu",
3375                 .data           = &ip_rt_min_pmtu,
3376                 .maxlen         = sizeof(int),
3377                 .mode           = 0644,
3378                 .proc_handler   = proc_dointvec_minmax,
3379                 .extra1         = &ip_min_valid_pmtu,
3380         },
3381         {
3382                 .procname       = "min_adv_mss",
3383                 .data           = &ip_rt_min_advmss,
3384                 .maxlen         = sizeof(int),
3385                 .mode           = 0644,
3386                 .proc_handler   = proc_dointvec,
3387         },
3388         { }
3389 };
3390
3391 static const char ipv4_route_flush_procname[] = "flush";
3392
3393 static struct ctl_table ipv4_route_flush_table[] = {
3394         {
3395                 .procname       = ipv4_route_flush_procname,
3396                 .maxlen         = sizeof(int),
3397                 .mode           = 0200,
3398                 .proc_handler   = ipv4_sysctl_rtcache_flush,
3399         },
3400         { },
3401 };
3402
3403 static __net_init int sysctl_route_net_init(struct net *net)
3404 {
3405         struct ctl_table *tbl;
3406
3407         tbl = ipv4_route_flush_table;
3408         if (!net_eq(net, &init_net)) {
3409                 tbl = kmemdup(tbl, sizeof(ipv4_route_flush_table), GFP_KERNEL);
3410                 if (!tbl)
3411                         goto err_dup;
3412
3413                 /* Don't export non-whitelisted sysctls to unprivileged users */
3414                 if (net->user_ns != &init_user_ns) {
3415                         if (tbl[0].procname != ipv4_route_flush_procname)
3416                                 tbl[0].procname = NULL;
3417                 }
3418         }
3419         tbl[0].extra1 = net;
3420
3421         net->ipv4.route_hdr = register_net_sysctl(net, "net/ipv4/route", tbl);
3422         if (!net->ipv4.route_hdr)
3423                 goto err_reg;
3424         return 0;
3425
3426 err_reg:
3427         if (tbl != ipv4_route_flush_table)
3428                 kfree(tbl);
3429 err_dup:
3430         return -ENOMEM;
3431 }
3432
3433 static __net_exit void sysctl_route_net_exit(struct net *net)
3434 {
3435         struct ctl_table *tbl;
3436
3437         tbl = net->ipv4.route_hdr->ctl_table_arg;
3438         unregister_net_sysctl_table(net->ipv4.route_hdr);
3439         BUG_ON(tbl == ipv4_route_flush_table);
3440         kfree(tbl);
3441 }
3442
3443 static __net_initdata struct pernet_operations sysctl_route_ops = {
3444         .init = sysctl_route_net_init,
3445         .exit = sysctl_route_net_exit,
3446 };
3447 #endif
3448
3449 static __net_init int rt_genid_init(struct net *net)
3450 {
3451         atomic_set(&net->ipv4.rt_genid, 0);
3452         atomic_set(&net->fnhe_genid, 0);
3453         atomic_set(&net->ipv4.dev_addr_genid, get_random_int());
3454         return 0;
3455 }
3456
3457 static __net_initdata struct pernet_operations rt_genid_ops = {
3458         .init = rt_genid_init,
3459 };
3460
3461 static int __net_init ipv4_inetpeer_init(struct net *net)
3462 {
3463         struct inet_peer_base *bp = kmalloc(sizeof(*bp), GFP_KERNEL);
3464
3465         if (!bp)
3466                 return -ENOMEM;
3467         inet_peer_base_init(bp);
3468         net->ipv4.peers = bp;
3469         return 0;
3470 }
3471
3472 static void __net_exit ipv4_inetpeer_exit(struct net *net)
3473 {
3474         struct inet_peer_base *bp = net->ipv4.peers;
3475
3476         net->ipv4.peers = NULL;
3477         inetpeer_invalidate_tree(bp);
3478         kfree(bp);
3479 }
3480
3481 static __net_initdata struct pernet_operations ipv4_inetpeer_ops = {
3482         .init   =       ipv4_inetpeer_init,
3483         .exit   =       ipv4_inetpeer_exit,
3484 };
3485
3486 #ifdef CONFIG_IP_ROUTE_CLASSID
3487 struct ip_rt_acct __percpu *ip_rt_acct __read_mostly;
3488 #endif /* CONFIG_IP_ROUTE_CLASSID */
3489
3490 int __init ip_rt_init(void)
3491 {
3492         int cpu;
3493
3494         ip_idents = kmalloc_array(IP_IDENTS_SZ, sizeof(*ip_idents),
3495                                   GFP_KERNEL);
3496         if (!ip_idents)
3497                 panic("IP: failed to allocate ip_idents\n");
3498
3499         prandom_bytes(ip_idents, IP_IDENTS_SZ * sizeof(*ip_idents));
3500
3501         ip_tstamps = kcalloc(IP_IDENTS_SZ, sizeof(*ip_tstamps), GFP_KERNEL);
3502         if (!ip_tstamps)
3503                 panic("IP: failed to allocate ip_tstamps\n");
3504
3505         for_each_possible_cpu(cpu) {
3506                 struct uncached_list *ul = &per_cpu(rt_uncached_list, cpu);
3507
3508                 INIT_LIST_HEAD(&ul->head);
3509                 spin_lock_init(&ul->lock);
3510         }
3511 #ifdef CONFIG_IP_ROUTE_CLASSID
3512         ip_rt_acct = __alloc_percpu(256 * sizeof(struct ip_rt_acct), __alignof__(struct ip_rt_acct));
3513         if (!ip_rt_acct)
3514                 panic("IP: failed to allocate ip_rt_acct\n");
3515 #endif
3516
3517         ipv4_dst_ops.kmem_cachep =
3518                 kmem_cache_create("ip_dst_cache", sizeof(struct rtable), 0,
3519                                   SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
3520
3521         ipv4_dst_blackhole_ops.kmem_cachep = ipv4_dst_ops.kmem_cachep;
3522
3523         if (dst_entries_init(&ipv4_dst_ops) < 0)
3524                 panic("IP: failed to allocate ipv4_dst_ops counter\n");
3525
3526         if (dst_entries_init(&ipv4_dst_blackhole_ops) < 0)
3527                 panic("IP: failed to allocate ipv4_dst_blackhole_ops counter\n");
3528
3529         ipv4_dst_ops.gc_thresh = ~0;
3530         ip_rt_max_size = INT_MAX;
3531
3532         devinet_init();
3533         ip_fib_init();
3534
3535         if (ip_rt_proc_init())
3536                 pr_err("Unable to create route proc files\n");
3537 #ifdef CONFIG_XFRM
3538         xfrm_init();
3539         xfrm4_init();
3540 #endif
3541         rtnl_register(PF_INET, RTM_GETROUTE, inet_rtm_getroute, NULL,
3542                       RTNL_FLAG_DOIT_UNLOCKED);
3543
3544 #ifdef CONFIG_SYSCTL
3545         register_pernet_subsys(&sysctl_route_ops);
3546 #endif
3547         register_pernet_subsys(&rt_genid_ops);
3548         register_pernet_subsys(&ipv4_inetpeer_ops);
3549         return 0;
3550 }
3551
3552 #ifdef CONFIG_SYSCTL
3553 /*
3554  * We really need to sanitize the damn ipv4 init order, then all
3555  * this nonsense will go away.
3556  */
3557 void __init ip_static_sysctl_init(void)
3558 {
3559         register_net_sysctl(&init_net, "net/ipv4/route", ipv4_route_table);
3560 }
3561 #endif