net/ipv6/ip6_output.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *      IPv6 output functions
   4  *      Linux INET6 implementation
   5  *
   6  *      Authors:
   7  *      Pedro Roque             <roque@di.fc.ul.pt>
   8  *
   9  *      Based on linux/net/ipv4/ip_output.c
  10  *
  11  *      Changes:
  12  *      A.N.Kuznetsov   :       airthmetics in fragmentation.
  13  *                              extension headers are implemented.
  14  *                              route changes now work.
  15  *                              ip6_forward does not confuse sniffers.
  16  *                              etc.
  17  *
  18  *      H. von Brand    :       Added missing #include <linux/string.h>
  19  *      Imran Patel     :       frag id should be in NBO
  20  *      Kazunori MIYAZAWA @USAGI
  21  *                      :       add ip6_append_data and related functions
  22  *                              for datagram xmit
  23  */
  24
  25 #include <linux/errno.h>
  26 #include <linux/kernel.h>
  27 #include <linux/string.h>
  28 #include <linux/socket.h>
  29 #include <linux/net.h>
  30 #include <linux/netdevice.h>
  31 #include <linux/if_arp.h>
  32 #include <linux/in6.h>
  33 #include <linux/tcp.h>
  34 #include <linux/route.h>
  35 #include <linux/module.h>
  36 #include <linux/slab.h>
  37
  38 #include <linux/bpf-cgroup.h>
  39 #include <linux/netfilter.h>
  40 #include <linux/netfilter_ipv6.h>
  41
  42 #include <net/sock.h>
  43 #include <net/snmp.h>
  44
  45 #include <net/gso.h>
  46 #include <net/ipv6.h>
  47 #include <net/ndisc.h>
  48 #include <net/protocol.h>
  49 #include <net/ip6_route.h>
  50 #include <net/addrconf.h>
  51 #include <net/rawv6.h>
  52 #include <net/icmp.h>
  53 #include <net/xfrm.h>
  54 #include <net/checksum.h>
  55 #include <linux/mroute6.h>
  56 #include <net/l3mdev.h>
  57 #include <net/lwtunnel.h>
  58 #include <net/ip_tunnels.h>
  59
  60 static int ip6_finish_output2(struct net *net, struct sock *sk, struct sk_buff *skb)
  61 {
  62         struct dst_entry *dst = skb_dst(skb);
  63         struct net_device *dev = dst->dev;
  64         struct inet6_dev *idev = ip6_dst_idev(dst);
  65         unsigned int hh_len = LL_RESERVED_SPACE(dev);
  66         const struct in6_addr *daddr, *nexthop;
  67         struct ipv6hdr *hdr;
  68         struct neighbour *neigh;
  69         int ret;
  70
  71         /* Be paranoid, rather than too clever. */
  72         if (unlikely(hh_len > skb_headroom(skb)) && dev->header_ops) {
  73                 skb = skb_expand_head(skb, hh_len);
  74                 if (!skb) {
  75                         IP6_INC_STATS(net, idev, IPSTATS_MIB_OUTDISCARDS);
  76                         return -ENOMEM;
  77                 }
  78         }
  79
  80         hdr = ipv6_hdr(skb);
  81         daddr = &hdr->daddr;
  82         if (ipv6_addr_is_multicast(daddr)) {
  83                 if (!(dev->flags & IFF_LOOPBACK) && sk_mc_loop(sk) &&
  84                     ((mroute6_is_socket(net, skb) &&
  85                      !(IP6CB(skb)->flags & IP6SKB_FORWARDED)) ||
  86                      ipv6_chk_mcast_addr(dev, daddr, &hdr->saddr))) {
  87                         struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
  88
  89                         /* Do not check for IFF_ALLMULTI; multicast routing
  90                            is not supported in any case.
  91                          */
  92                         if (newskb)
  93                                 NF_HOOK(NFPROTO_IPV6, NF_INET_POST_ROUTING,
  94                                         net, sk, newskb, NULL, newskb->dev,
  95                                         dev_loopback_xmit);
  96
  97                         if (hdr->hop_limit == 0) {
  98                                 IP6_INC_STATS(net, idev,
  99                                               IPSTATS_MIB_OUTDISCARDS);
 100                                 kfree_skb(skb);
 101                                 return 0;
 102                         }
 103                 }
 104
 105                 IP6_UPD_PO_STATS(net, idev, IPSTATS_MIB_OUTMCAST, skb->len);
 106                 if (IPV6_ADDR_MC_SCOPE(daddr) <= IPV6_ADDR_SCOPE_NODELOCAL &&
 107                     !(dev->flags & IFF_LOOPBACK)) {
 108                         kfree_skb(skb);
 109                         return 0;
 110                 }
 111         }
 112
 113         if (lwtunnel_xmit_redirect(dst->lwtstate)) {
 114                 int res = lwtunnel_xmit(skb);
 115
 116                 if (res != LWTUNNEL_XMIT_CONTINUE)
 117                         return res;
 118         }
 119
 120         rcu_read_lock();
 121         nexthop = rt6_nexthop((struct rt6_info *)dst, daddr);
 122         neigh = __ipv6_neigh_lookup_noref(dev, nexthop);
 123
 124         if (unlikely(IS_ERR_OR_NULL(neigh))) {
 125                 if (unlikely(!neigh))
 126                         neigh = __neigh_create(&nd_tbl, nexthop, dev, false);
 127                 if (IS_ERR(neigh)) {
 128                         rcu_read_unlock();
 129                         IP6_INC_STATS(net, idev, IPSTATS_MIB_OUTNOROUTES);
 130                         kfree_skb_reason(skb, SKB_DROP_REASON_NEIGH_CREATEFAIL);
 131                         return -EINVAL;
 132                 }
 133         }
 134         sock_confirm_neigh(skb, neigh);
 135         ret = neigh_output(neigh, skb, false);
 136         rcu_read_unlock();
 137         return ret;
 138 }
 139
 140 static int
 141 ip6_finish_output_gso_slowpath_drop(struct net *net, struct sock *sk,
 142                                     struct sk_buff *skb, unsigned int mtu)
 143 {
 144         struct sk_buff *segs, *nskb;
 145         netdev_features_t features;
 146         int ret = 0;
 147
 148         /* Please see corresponding comment in ip_finish_output_gso
 149          * describing the cases where GSO segment length exceeds the
 150          * egress MTU.
 151          */
 152         features = netif_skb_features(skb);
 153         segs = skb_gso_segment(skb, features & ~NETIF_F_GSO_MASK);
 154         if (IS_ERR_OR_NULL(segs)) {
 155                 kfree_skb(skb);
 156                 return -ENOMEM;
 157         }
 158
 159         consume_skb(skb);
 160
 161         skb_list_walk_safe(segs, segs, nskb) {
 162                 int err;
 163
 164                 skb_mark_not_on_list(segs);
 165                 /* Last GSO segment can be smaller than gso_size (and MTU).
 166                  * Adding a fragment header would produce an "atomic fragment",
 167                  * which is considered harmful (RFC-8021). Avoid that.
 168                  */
 169                 err = segs->len > mtu ?
 170                         ip6_fragment(net, sk, segs, ip6_finish_output2) :
 171                         ip6_finish_output2(net, sk, segs);
 172                 if (err && ret == 0)
 173                         ret = err;
 174         }
 175
 176         return ret;
 177 }
 178
 179 static int __ip6_finish_output(struct net *net, struct sock *sk, struct sk_buff *skb)
 180 {
 181         unsigned int mtu;
 182
 183 #if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM)
 184         /* Policy lookup after SNAT yielded a new policy */
 185         if (skb_dst(skb)->xfrm) {
 186                 IP6CB(skb)->flags |= IP6SKB_REROUTED;
 187                 return dst_output(net, sk, skb);
 188         }
 189 #endif
 190
 191         mtu = ip6_skb_dst_mtu(skb);
 192         if (skb_is_gso(skb) &&
 193             !(IP6CB(skb)->flags & IP6SKB_FAKEJUMBO) &&
 194             !skb_gso_validate_network_len(skb, mtu))
 195                 return ip6_finish_output_gso_slowpath_drop(net, sk, skb, mtu);
 196
 197         if ((skb->len > mtu && !skb_is_gso(skb)) ||
 198             dst_allfrag(skb_dst(skb)) ||
 199             (IP6CB(skb)->frag_max_size && skb->len > IP6CB(skb)->frag_max_size))
 200                 return ip6_fragment(net, sk, skb, ip6_finish_output2);
 201         else
 202                 return ip6_finish_output2(net, sk, skb);
 203 }
 204
 205 static int ip6_finish_output(struct net *net, struct sock *sk, struct sk_buff *skb)
 206 {
 207         int ret;
 208
 209         ret = BPF_CGROUP_RUN_PROG_INET_EGRESS(sk, skb);
 210         switch (ret) {
 211         case NET_XMIT_SUCCESS:
 212         case NET_XMIT_CN:
 213                 return __ip6_finish_output(net, sk, skb) ? : ret;
 214         default:
 215                 kfree_skb_reason(skb, SKB_DROP_REASON_BPF_CGROUP_EGRESS);
 216                 return ret;
 217         }
 218 }
 219
 220 int ip6_output(struct net *net, struct sock *sk, struct sk_buff *skb)
 221 {
 222         struct net_device *dev = skb_dst(skb)->dev, *indev = skb->dev;
 223         struct inet6_dev *idev = ip6_dst_idev(skb_dst(skb));
 224
 225         skb->protocol = htons(ETH_P_IPV6);
 226         skb->dev = dev;
 227
 228         if (unlikely(idev->cnf.disable_ipv6)) {
 229                 IP6_INC_STATS(net, idev, IPSTATS_MIB_OUTDISCARDS);
 230                 kfree_skb_reason(skb, SKB_DROP_REASON_IPV6DISABLED);
 231                 return 0;
 232         }
 233
 234         return NF_HOOK_COND(NFPROTO_IPV6, NF_INET_POST_ROUTING,
 235                             net, sk, skb, indev, dev,
 236                             ip6_finish_output,
 237                             !(IP6CB(skb)->flags & IP6SKB_REROUTED));
 238 }
 239 EXPORT_SYMBOL(ip6_output);
 240
 241 bool ip6_autoflowlabel(struct net *net, const struct ipv6_pinfo *np)
 242 {
 243         if (!np->autoflowlabel_set)
 244                 return ip6_default_np_autolabel(net);
 245         else
 246                 return np->autoflowlabel;
 247 }
 248
 249 /*
 250  * xmit an sk_buff (used by TCP, SCTP and DCCP)
 251  * Note : socket lock is not held for SYNACK packets, but might be modified
 252  * by calls to skb_set_owner_w() and ipv6_local_error(),
 253  * which are using proper atomic operations or spinlocks.
 254  */
 255 int ip6_xmit(const struct sock *sk, struct sk_buff *skb, struct flowi6 *fl6,
 256              __u32 mark, struct ipv6_txoptions *opt, int tclass, u32 priority)
 257 {
 258         struct net *net = sock_net(sk);
 259         const struct ipv6_pinfo *np = inet6_sk(sk);
 260         struct in6_addr *first_hop = &fl6->daddr;
 261         struct dst_entry *dst = skb_dst(skb);
 262         struct net_device *dev = dst->dev;
 263         struct inet6_dev *idev = ip6_dst_idev(dst);
 264         struct hop_jumbo_hdr *hop_jumbo;
 265         int hoplen = sizeof(*hop_jumbo);
 266         unsigned int head_room;
 267         struct ipv6hdr *hdr;
 268         u8  proto = fl6->flowi6_proto;
 269         int seg_len = skb->len;
 270         int hlimit = -1;
 271         u32 mtu;
 272
 273         head_room = sizeof(struct ipv6hdr) + hoplen + LL_RESERVED_SPACE(dev);
 274         if (opt)
 275                 head_room += opt->opt_nflen + opt->opt_flen;
 276
 277         if (unlikely(head_room > skb_headroom(skb))) {
 278                 skb = skb_expand_head(skb, head_room);
 279                 if (!skb) {
 280                         IP6_INC_STATS(net, idev, IPSTATS_MIB_OUTDISCARDS);
 281                         return -ENOBUFS;
 282                 }
 283         }
 284
 285         if (opt) {
 286                 seg_len += opt->opt_nflen + opt->opt_flen;
 287
 288                 if (opt->opt_flen)
 289                         ipv6_push_frag_opts(skb, opt, &proto);
 290
 291                 if (opt->opt_nflen)
 292                         ipv6_push_nfrag_opts(skb, opt, &proto, &first_hop,
 293                                              &fl6->saddr);
 294         }
 295
 296         if (unlikely(seg_len > IPV6_MAXPLEN)) {
 297                 hop_jumbo = skb_push(skb, hoplen);
 298
 299                 hop_jumbo->nexthdr = proto;
 300                 hop_jumbo->hdrlen = 0;
 301                 hop_jumbo->tlv_type = IPV6_TLV_JUMBO;
 302                 hop_jumbo->tlv_len = 4;
 303                 hop_jumbo->jumbo_payload_len = htonl(seg_len + hoplen);
 304
 305                 proto = IPPROTO_HOPOPTS;
 306                 seg_len = 0;
 307                 IP6CB(skb)->flags |= IP6SKB_FAKEJUMBO;
 308         }
 309
 310         skb_push(skb, sizeof(struct ipv6hdr));
 311         skb_reset_network_header(skb);
 312         hdr = ipv6_hdr(skb);
 313
 314         /*
 315          *      Fill in the IPv6 header
 316          */
 317         if (np)
 318                 hlimit = np->hop_limit;
 319         if (hlimit < 0)
 320                 hlimit = ip6_dst_hoplimit(dst);
 321
 322         ip6_flow_hdr(hdr, tclass, ip6_make_flowlabel(net, skb, fl6->flowlabel,
 323                                 ip6_autoflowlabel(net, np), fl6));
 324
 325         hdr->payload_len = htons(seg_len);
 326         hdr->nexthdr = proto;
 327         hdr->hop_limit = hlimit;
 328
 329         hdr->saddr = fl6->saddr;
 330         hdr->daddr = *first_hop;
 331
 332         skb->protocol = htons(ETH_P_IPV6);
 333         skb->priority = priority;
 334         skb->mark = mark;
 335
 336         mtu = dst_mtu(dst);
 337         if ((skb->len <= mtu) || skb->ignore_df || skb_is_gso(skb)) {
 338                 IP6_UPD_PO_STATS(net, idev, IPSTATS_MIB_OUT, skb->len);
 339
 340                 /* if egress device is enslaved to an L3 master device pass the
 341                  * skb to its handler for processing
 342                  */
 343                 skb = l3mdev_ip6_out((struct sock *)sk, skb);
 344                 if (unlikely(!skb))
 345                         return 0;
 346
 347                 /* hooks should never assume socket lock is held.
 348                  * we promote our socket to non const
 349                  */
 350                 return NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_OUT,
 351                                net, (struct sock *)sk, skb, NULL, dev,
 352                                dst_output);
 353         }
 354
 355         skb->dev = dev;
 356         /* ipv6_local_error() does not require socket lock,
 357          * we promote our socket to non const
 358          */
 359         ipv6_local_error((struct sock *)sk, EMSGSIZE, fl6, mtu);
 360
 361         IP6_INC_STATS(net, idev, IPSTATS_MIB_FRAGFAILS);
 362         kfree_skb(skb);
 363         return -EMSGSIZE;
 364 }
 365 EXPORT_SYMBOL(ip6_xmit);
 366
 367 static int ip6_call_ra_chain(struct sk_buff *skb, int sel)
 368 {
 369         struct ip6_ra_chain *ra;
 370         struct sock *last = NULL;
 371
 372         read_lock(&ip6_ra_lock);
 373         for (ra = ip6_ra_chain; ra; ra = ra->next) {
 374                 struct sock *sk = ra->sk;
 375                 if (sk && ra->sel == sel &&
 376                     (!sk->sk_bound_dev_if ||
 377                      sk->sk_bound_dev_if == skb->dev->ifindex)) {
 378                         struct ipv6_pinfo *np = inet6_sk(sk);
 379
 380                         if (np && np->rtalert_isolate &&
 381                             !net_eq(sock_net(sk), dev_net(skb->dev))) {
 382                                 continue;
 383                         }
 384                         if (last) {
 385                                 struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);
 386                                 if (skb2)
 387                                         rawv6_rcv(last, skb2);
 388                         }
 389                         last = sk;
 390                 }
 391         }
 392
 393         if (last) {
 394                 rawv6_rcv(last, skb);
 395                 read_unlock(&ip6_ra_lock);
 396                 return 1;
 397         }
 398         read_unlock(&ip6_ra_lock);
 399         return 0;
 400 }
 401
 402 static int ip6_forward_proxy_check(struct sk_buff *skb)
 403 {
 404         struct ipv6hdr *hdr = ipv6_hdr(skb);
 405         u8 nexthdr = hdr->nexthdr;
 406         __be16 frag_off;
 407         int offset;
 408
 409         if (ipv6_ext_hdr(nexthdr)) {
 410                 offset = ipv6_skip_exthdr(skb, sizeof(*hdr), &nexthdr, &frag_off);
 411                 if (offset < 0)
 412                         return 0;
 413         } else
 414                 offset = sizeof(struct ipv6hdr);
 415
 416         if (nexthdr == IPPROTO_ICMPV6) {
 417                 struct icmp6hdr *icmp6;
 418
 419                 if (!pskb_may_pull(skb, (skb_network_header(skb) +
 420                                          offset + 1 - skb->data)))
 421                         return 0;
 422
 423                 icmp6 = (struct icmp6hdr *)(skb_network_header(skb) + offset);
 424
 425                 switch (icmp6->icmp6_type) {
 426                 case NDISC_ROUTER_SOLICITATION:
 427                 case NDISC_ROUTER_ADVERTISEMENT:
 428                 case NDISC_NEIGHBOUR_SOLICITATION:
 429                 case NDISC_NEIGHBOUR_ADVERTISEMENT:
 430                 case NDISC_REDIRECT:
 431                         /* For reaction involving unicast neighbor discovery
 432                          * message destined to the proxied address, pass it to
 433                          * input function.
 434                          */
 435                         return 1;
 436                 default:
 437                         break;
 438                 }
 439         }
 440
 441         /*
 442          * The proxying router can't forward traffic sent to a link-local
 443          * address, so signal the sender and discard the packet. This
 444          * behavior is clarified by the MIPv6 specification.
 445          */
 446         if (ipv6_addr_type(&hdr->daddr) & IPV6_ADDR_LINKLOCAL) {
 447                 dst_link_failure(skb);
 448                 return -1;
 449         }
 450
 451         return 0;
 452 }
 453
 454 static inline int ip6_forward_finish(struct net *net, struct sock *sk,
 455                                      struct sk_buff *skb)
 456 {
 457         struct dst_entry *dst = skb_dst(skb);
 458
 459         __IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTFORWDATAGRAMS);
 460
 461 #ifdef CONFIG_NET_SWITCHDEV
 462         if (skb->offload_l3_fwd_mark) {
 463                 consume_skb(skb);
 464                 return 0;
 465         }
 466 #endif
 467
 468         skb_clear_tstamp(skb);
 469         return dst_output(net, sk, skb);
 470 }
 471
 472 static bool ip6_pkt_too_big(const struct sk_buff *skb, unsigned int mtu)
 473 {
 474         if (skb->len <= mtu)
 475                 return false;
 476
 477         /* ipv6 conntrack defrag sets max_frag_size + ignore_df */
 478         if (IP6CB(skb)->frag_max_size && IP6CB(skb)->frag_max_size > mtu)
 479                 return true;
 480
 481         if (skb->ignore_df)
 482                 return false;
 483
 484         if (skb_is_gso(skb) && skb_gso_validate_network_len(skb, mtu))
 485                 return false;
 486
 487         return true;
 488 }
 489
 490 int ip6_forward(struct sk_buff *skb)
 491 {
 492         struct dst_entry *dst = skb_dst(skb);
 493         struct ipv6hdr *hdr = ipv6_hdr(skb);
 494         struct inet6_skb_parm *opt = IP6CB(skb);
 495         struct net *net = dev_net(dst->dev);
 496         struct inet6_dev *idev;
 497         SKB_DR(reason);
 498         u32 mtu;
 499
 500         idev = __in6_dev_get_safely(dev_get_by_index_rcu(net, IP6CB(skb)->iif));
 501         if (net->ipv6.devconf_all->forwarding == 0)
 502                 goto error;
 503
 504         if (skb->pkt_type != PACKET_HOST)
 505                 goto drop;
 506
 507         if (unlikely(skb->sk))
 508                 goto drop;
 509
 510         if (skb_warn_if_lro(skb))
 511                 goto drop;
 512
 513         if (!net->ipv6.devconf_all->disable_policy &&
 514             (!idev || !idev->cnf.disable_policy) &&
 515             !xfrm6_policy_check(NULL, XFRM_POLICY_FWD, skb)) {
 516                 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INDISCARDS);
 517                 goto drop;
 518         }
 519
 520         skb_forward_csum(skb);
 521
 522         /*
 523          *      We DO NOT make any processing on
 524          *      RA packets, pushing them to user level AS IS
 525          *      without ane WARRANTY that application will be able
 526          *      to interpret them. The reason is that we
 527          *      cannot make anything clever here.
 528          *
 529          *      We are not end-node, so that if packet contains
 530          *      AH/ESP, we cannot make anything.
 531          *      Defragmentation also would be mistake, RA packets
 532          *      cannot be fragmented, because there is no warranty
 533          *      that different fragments will go along one path. --ANK
 534          */
 535         if (unlikely(opt->flags & IP6SKB_ROUTERALERT)) {
 536                 if (ip6_call_ra_chain(skb, ntohs(opt->ra)))
 537                         return 0;
 538         }
 539
 540         /*
 541          *      check and decrement ttl
 542          */
 543         if (hdr->hop_limit <= 1) {
 544                 icmpv6_send(skb, ICMPV6_TIME_EXCEED, ICMPV6_EXC_HOPLIMIT, 0);
 545                 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
 546
 547                 kfree_skb_reason(skb, SKB_DROP_REASON_IP_INHDR);
 548                 return -ETIMEDOUT;
 549         }
 550
 551         /* XXX: idev->cnf.proxy_ndp? */
 552         if (net->ipv6.devconf_all->proxy_ndp &&
 553             pneigh_lookup(&nd_tbl, net, &hdr->daddr, skb->dev, 0)) {
 554                 int proxied = ip6_forward_proxy_check(skb);
 555                 if (proxied > 0) {
 556                         /* It's tempting to decrease the hop limit
 557                          * here by 1, as we do at the end of the
 558                          * function too.
 559                          *
 560                          * But that would be incorrect, as proxying is
 561                          * not forwarding.  The ip6_input function
 562                          * will handle this packet locally, and it
 563                          * depends on the hop limit being unchanged.
 564                          *
 565                          * One example is the NDP hop limit, that
 566                          * always has to stay 255, but other would be
 567                          * similar checks around RA packets, where the
 568                          * user can even change the desired limit.
 569                          */
 570                         return ip6_input(skb);
 571                 } else if (proxied < 0) {
 572                         __IP6_INC_STATS(net, idev, IPSTATS_MIB_INDISCARDS);
 573                         goto drop;
 574                 }
 575         }
 576
 577         if (!xfrm6_route_forward(skb)) {
 578                 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INDISCARDS);
 579                 SKB_DR_SET(reason, XFRM_POLICY);
 580                 goto drop;
 581         }
 582         dst = skb_dst(skb);
 583
 584         /* IPv6 specs say nothing about it, but it is clear that we cannot
 585            send redirects to source routed frames.
 586            We don't send redirects to frames decapsulated from IPsec.
 587          */
 588         if (IP6CB(skb)->iif == dst->dev->ifindex &&
 589             opt->srcrt == 0 && !skb_sec_path(skb)) {
 590                 struct in6_addr *target = NULL;
 591                 struct inet_peer *peer;
 592                 struct rt6_info *rt;
 593
 594                 /*
 595                  *      incoming and outgoing devices are the same
 596                  *      send a redirect.
 597                  */
 598
 599                 rt = (struct rt6_info *) dst;
 600                 if (rt->rt6i_flags & RTF_GATEWAY)
 601                         target = &rt->rt6i_gateway;
 602                 else
 603                         target = &hdr->daddr;
 604
 605                 peer = inet_getpeer_v6(net->ipv6.peers, &hdr->daddr, 1);
 606
 607                 /* Limit redirects both by destination (here)
 608                    and by source (inside ndisc_send_redirect)
 609                  */
 610                 if (inet_peer_xrlim_allow(peer, 1*HZ))
 611                         ndisc_send_redirect(skb, target);
 612                 if (peer)
 613                         inet_putpeer(peer);
 614         } else {
 615                 int addrtype = ipv6_addr_type(&hdr->saddr);
 616
 617                 /* This check is security critical. */
 618                 if (addrtype == IPV6_ADDR_ANY ||
 619                     addrtype & (IPV6_ADDR_MULTICAST | IPV6_ADDR_LOOPBACK))
 620                         goto error;
 621                 if (addrtype & IPV6_ADDR_LINKLOCAL) {
 622                         icmpv6_send(skb, ICMPV6_DEST_UNREACH,
 623                                     ICMPV6_NOT_NEIGHBOUR, 0);
 624                         goto error;
 625                 }
 626         }
 627
 628         mtu = ip6_dst_mtu_maybe_forward(dst, true);
 629         if (mtu < IPV6_MIN_MTU)
 630                 mtu = IPV6_MIN_MTU;
 631
 632         if (ip6_pkt_too_big(skb, mtu)) {
 633                 /* Again, force OUTPUT device used as source address */
 634                 skb->dev = dst->dev;
 635                 icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
 636                 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INTOOBIGERRORS);
 637                 __IP6_INC_STATS(net, ip6_dst_idev(dst),
 638                                 IPSTATS_MIB_FRAGFAILS);
 639                 kfree_skb_reason(skb, SKB_DROP_REASON_PKT_TOO_BIG);
 640                 return -EMSGSIZE;
 641         }
 642
 643         if (skb_cow(skb, dst->dev->hard_header_len)) {
 644                 __IP6_INC_STATS(net, ip6_dst_idev(dst),
 645                                 IPSTATS_MIB_OUTDISCARDS);
 646                 goto drop;
 647         }
 648
 649         hdr = ipv6_hdr(skb);
 650
 651         /* Mangling hops number delayed to point after skb COW */
 652
 653         hdr->hop_limit--;
 654
 655         return NF_HOOK(NFPROTO_IPV6, NF_INET_FORWARD,
 656                        net, NULL, skb, skb->dev, dst->dev,
 657                        ip6_forward_finish);
 658
 659 error:
 660         __IP6_INC_STATS(net, idev, IPSTATS_MIB_INADDRERRORS);
 661         SKB_DR_SET(reason, IP_INADDRERRORS);
 662 drop:
 663         kfree_skb_reason(skb, reason);
 664         return -EINVAL;
 665 }
 666
 667 static void ip6_copy_metadata(struct sk_buff *to, struct sk_buff *from)
 668 {
 669         to->pkt_type = from->pkt_type;
 670         to->priority = from->priority;
 671         to->protocol = from->protocol;
 672         skb_dst_drop(to);
 673         skb_dst_set(to, dst_clone(skb_dst(from)));
 674         to->dev = from->dev;
 675         to->mark = from->mark;
 676
 677         skb_copy_hash(to, from);
 678
 679 #ifdef CONFIG_NET_SCHED
 680         to->tc_index = from->tc_index;
 681 #endif
 682         nf_copy(to, from);
 683         skb_ext_copy(to, from);
 684         skb_copy_secmark(to, from);
 685 }
 686
 687 int ip6_fraglist_init(struct sk_buff *skb, unsigned int hlen, u8 *prevhdr,
 688                       u8 nexthdr, __be32 frag_id,
 689                       struct ip6_fraglist_iter *iter)
 690 {
 691         unsigned int first_len;
 692         struct frag_hdr *fh;
 693
 694         /* BUILD HEADER */
 695         *prevhdr = NEXTHDR_FRAGMENT;
 696         iter->tmp_hdr = kmemdup(skb_network_header(skb), hlen, GFP_ATOMIC);
 697         if (!iter->tmp_hdr)
 698                 return -ENOMEM;
 699
 700         iter->frag = skb_shinfo(skb)->frag_list;
 701         skb_frag_list_init(skb);
 702
 703         iter->offset = 0;
 704         iter->hlen = hlen;
 705         iter->frag_id = frag_id;
 706         iter->nexthdr = nexthdr;
 707
 708         __skb_pull(skb, hlen);
 709         fh = __skb_push(skb, sizeof(struct frag_hdr));
 710         __skb_push(skb, hlen);
 711         skb_reset_network_header(skb);
 712         memcpy(skb_network_header(skb), iter->tmp_hdr, hlen);
 713
 714         fh->nexthdr = nexthdr;
 715         fh->reserved = 0;
 716         fh->frag_off = htons(IP6_MF);
 717         fh->identification = frag_id;
 718
 719         first_len = skb_pagelen(skb);
 720         skb->data_len = first_len - skb_headlen(skb);
 721         skb->len = first_len;
 722         ipv6_hdr(skb)->payload_len = htons(first_len - sizeof(struct ipv6hdr));
 723
 724         return 0;
 725 }
 726 EXPORT_SYMBOL(ip6_fraglist_init);
 727
 728 void ip6_fraglist_prepare(struct sk_buff *skb,
 729                           struct ip6_fraglist_iter *iter)
 730 {
 731         struct sk_buff *frag = iter->frag;
 732         unsigned int hlen = iter->hlen;
 733         struct frag_hdr *fh;
 734
 735         frag->ip_summed = CHECKSUM_NONE;
 736         skb_reset_transport_header(frag);
 737         fh = __skb_push(frag, sizeof(struct frag_hdr));
 738         __skb_push(frag, hlen);
 739         skb_reset_network_header(frag);
 740         memcpy(skb_network_header(frag), iter->tmp_hdr, hlen);
 741         iter->offset += skb->len - hlen - sizeof(struct frag_hdr);
 742         fh->nexthdr = iter->nexthdr;
 743         fh->reserved = 0;
 744         fh->frag_off = htons(iter->offset);
 745         if (frag->next)
 746                 fh->frag_off |= htons(IP6_MF);
 747         fh->identification = iter->frag_id;
 748         ipv6_hdr(frag)->payload_len = htons(frag->len - sizeof(struct ipv6hdr));
 749         ip6_copy_metadata(frag, skb);
 750 }
 751 EXPORT_SYMBOL(ip6_fraglist_prepare);
 752
 753 void ip6_frag_init(struct sk_buff *skb, unsigned int hlen, unsigned int mtu,
 754                    unsigned short needed_tailroom, int hdr_room, u8 *prevhdr,
 755                    u8 nexthdr, __be32 frag_id, struct ip6_frag_state *state)
 756 {
 757         state->prevhdr = prevhdr;
 758         state->nexthdr = nexthdr;
 759         state->frag_id = frag_id;
 760
 761         state->hlen = hlen;
 762         state->mtu = mtu;
 763
 764         state->left = skb->len - hlen;  /* Space per frame */
 765         state->ptr = hlen;              /* Where to start from */
 766
 767         state->hroom = hdr_room;
 768         state->troom = needed_tailroom;
 769
 770         state->offset = 0;
 771 }
 772 EXPORT_SYMBOL(ip6_frag_init);
 773
 774 struct sk_buff *ip6_frag_next(struct sk_buff *skb, struct ip6_frag_state *state)
 775 {
 776         u8 *prevhdr = state->prevhdr, *fragnexthdr_offset;
 777         struct sk_buff *frag;
 778         struct frag_hdr *fh;
 779         unsigned int len;
 780
 781         len = state->left;
 782         /* IF: it doesn't fit, use 'mtu' - the data space left */
 783         if (len > state->mtu)
 784                 len = state->mtu;
 785         /* IF: we are not sending up to and including the packet end
 786            then align the next start on an eight byte boundary */
 787         if (len < state->left)
 788                 len &= ~7;
 789
 790         /* Allocate buffer */
 791         frag = alloc_skb(len + state->hlen + sizeof(struct frag_hdr) +
 792                          state->hroom + state->troom, GFP_ATOMIC);
 793         if (!frag)
 794                 return ERR_PTR(-ENOMEM);
 795
 796         /*
 797          *      Set up data on packet
 798          */
 799
 800         ip6_copy_metadata(frag, skb);
 801         skb_reserve(frag, state->hroom);
 802         skb_put(frag, len + state->hlen + sizeof(struct frag_hdr));
 803         skb_reset_network_header(frag);
 804         fh = (struct frag_hdr *)(skb_network_header(frag) + state->hlen);
 805         frag->transport_header = (frag->network_header + state->hlen +
 806                                   sizeof(struct frag_hdr));
 807
 808         /*
 809          *      Charge the memory for the fragment to any owner
 810          *      it might possess
 811          */
 812         if (skb->sk)
 813                 skb_set_owner_w(frag, skb->sk);
 814
 815         /*
 816          *      Copy the packet header into the new buffer.
 817          */
 818         skb_copy_from_linear_data(skb, skb_network_header(frag), state->hlen);
 819
 820         fragnexthdr_offset = skb_network_header(frag);
 821         fragnexthdr_offset += prevhdr - skb_network_header(skb);
 822         *fragnexthdr_offset = NEXTHDR_FRAGMENT;
 823
 824         /*
 825          *      Build fragment header.
 826          */
 827         fh->nexthdr = state->nexthdr;
 828         fh->reserved = 0;
 829         fh->identification = state->frag_id;
 830
 831         /*
 832          *      Copy a block of the IP datagram.
 833          */
 834         BUG_ON(skb_copy_bits(skb, state->ptr, skb_transport_header(frag),
 835                              len));
 836         state->left -= len;
 837
 838         fh->frag_off = htons(state->offset);
 839         if (state->left > 0)
 840                 fh->frag_off |= htons(IP6_MF);
 841         ipv6_hdr(frag)->payload_len = htons(frag->len - sizeof(struct ipv6hdr));
 842
 843         state->ptr += len;
 844         state->offset += len;
 845
 846         return frag;
 847 }
 848 EXPORT_SYMBOL(ip6_frag_next);
 849
 850 int ip6_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
 851                  int (*output)(struct net *, struct sock *, struct sk_buff *))
 852 {
 853         struct sk_buff *frag;
 854         struct rt6_info *rt = (struct rt6_info *)skb_dst(skb);
 855         struct ipv6_pinfo *np = skb->sk && !dev_recursion_level() ?
 856                                 inet6_sk(skb->sk) : NULL;
 857         bool mono_delivery_time = skb->mono_delivery_time;
 858         struct ip6_frag_state state;
 859         unsigned int mtu, hlen, nexthdr_offset;
 860         ktime_t tstamp = skb->tstamp;
 861         int hroom, err = 0;
 862         __be32 frag_id;
 863         u8 *prevhdr, nexthdr = 0;
 864
 865         err = ip6_find_1stfragopt(skb, &prevhdr);
 866         if (err < 0)
 867                 goto fail;
 868         hlen = err;
 869         nexthdr = *prevhdr;
 870         nexthdr_offset = prevhdr - skb_network_header(skb);
 871
 872         mtu = ip6_skb_dst_mtu(skb);
 873
 874         /* We must not fragment if the socket is set to force MTU discovery
 875          * or if the skb it not generated by a local socket.
 876          */
 877         if (unlikely(!skb->ignore_df && skb->len > mtu))
 878                 goto fail_toobig;
 879
 880         if (IP6CB(skb)->frag_max_size) {
 881                 if (IP6CB(skb)->frag_max_size > mtu)
 882                         goto fail_toobig;
 883
 884                 /* don't send fragments larger than what we received */
 885                 mtu = IP6CB(skb)->frag_max_size;
 886                 if (mtu < IPV6_MIN_MTU)
 887                         mtu = IPV6_MIN_MTU;
 888         }
 889
 890         if (np && np->frag_size < mtu) {
 891                 if (np->frag_size)
 892                         mtu = np->frag_size;
 893         }
 894         if (mtu < hlen + sizeof(struct frag_hdr) + 8)
 895                 goto fail_toobig;
 896         mtu -= hlen + sizeof(struct frag_hdr);
 897
 898         frag_id = ipv6_select_ident(net, &ipv6_hdr(skb)->daddr,
 899                                     &ipv6_hdr(skb)->saddr);
 900
 901         if (skb->ip_summed == CHECKSUM_PARTIAL &&
 902             (err = skb_checksum_help(skb)))
 903                 goto fail;
 904
 905         prevhdr = skb_network_header(skb) + nexthdr_offset;
 906         hroom = LL_RESERVED_SPACE(rt->dst.dev);
 907         if (skb_has_frag_list(skb)) {
 908                 unsigned int first_len = skb_pagelen(skb);
 909                 struct ip6_fraglist_iter iter;
 910                 struct sk_buff *frag2;
 911
 912                 if (first_len - hlen > mtu ||
 913                     ((first_len - hlen) & 7) ||
 914                     skb_cloned(skb) ||
 915                     skb_headroom(skb) < (hroom + sizeof(struct frag_hdr)))
 916                         goto slow_path;
 917
 918                 skb_walk_frags(skb, frag) {
 919                         /* Correct geometry. */
 920                         if (frag->len > mtu ||
 921                             ((frag->len & 7) && frag->next) ||
 922                             skb_headroom(frag) < (hlen + hroom + sizeof(struct frag_hdr)))
 923                                 goto slow_path_clean;
 924
 925                         /* Partially cloned skb? */
 926                         if (skb_shared(frag))
 927                                 goto slow_path_clean;
 928
 929                         BUG_ON(frag->sk);
 930                         if (skb->sk) {
 931                                 frag->sk = skb->sk;
 932                                 frag->destructor = sock_wfree;
 933                         }
 934                         skb->truesize -= frag->truesize;
 935                 }
 936
 937                 err = ip6_fraglist_init(skb, hlen, prevhdr, nexthdr, frag_id,
 938                                         &iter);
 939                 if (err < 0)
 940                         goto fail;
 941
 942                 /* We prevent @rt from being freed. */
 943                 rcu_read_lock();
 944
 945                 for (;;) {
 946                         /* Prepare header of the next frame,
 947                          * before previous one went down. */
 948                         if (iter.frag)
 949                                 ip6_fraglist_prepare(skb, &iter);
 950
 951                         skb_set_delivery_time(skb, tstamp, mono_delivery_time);
 952                         err = output(net, sk, skb);
 953                         if (!err)
 954                                 IP6_INC_STATS(net, ip6_dst_idev(&rt->dst),
 955                                               IPSTATS_MIB_FRAGCREATES);
 956
 957                         if (err || !iter.frag)
 958                                 break;
 959
 960                         skb = ip6_fraglist_next(&iter);
 961                 }
 962
 963                 kfree(iter.tmp_hdr);
 964
 965                 if (err == 0) {
 966                         IP6_INC_STATS(net, ip6_dst_idev(&rt->dst),
 967                                       IPSTATS_MIB_FRAGOKS);
 968                         rcu_read_unlock();
 969                         return 0;
 970                 }
 971
 972                 kfree_skb_list(iter.frag);
 973
 974                 IP6_INC_STATS(net, ip6_dst_idev(&rt->dst),
 975                               IPSTATS_MIB_FRAGFAILS);
 976                 rcu_read_unlock();
 977                 return err;
 978
 979 slow_path_clean:
 980                 skb_walk_frags(skb, frag2) {
 981                         if (frag2 == frag)
 982                                 break;
 983                         frag2->sk = NULL;
 984                         frag2->destructor = NULL;
 985                         skb->truesize += frag2->truesize;
 986                 }
 987         }
 988
 989 slow_path:
 990         /*
 991          *      Fragment the datagram.
 992          */
 993
 994         ip6_frag_init(skb, hlen, mtu, rt->dst.dev->needed_tailroom,
 995                       LL_RESERVED_SPACE(rt->dst.dev), prevhdr, nexthdr, frag_id,
 996                       &state);
 997
 998         /*
 999          *      Keep copying data until we run out.
1000          */
1001
1002         while (state.left > 0) {
1003                 frag = ip6_frag_next(skb, &state);
1004                 if (IS_ERR(frag)) {
1005                         err = PTR_ERR(frag);
1006                         goto fail;
1007                 }
1008
1009                 /*
1010                  *      Put this fragment into the sending queue.
1011                  */
1012                 skb_set_delivery_time(frag, tstamp, mono_delivery_time);
1013                 err = output(net, sk, frag);
1014                 if (err)
1015                         goto fail;
1016
1017                 IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
1018                               IPSTATS_MIB_FRAGCREATES);
1019         }
1020         IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
1021                       IPSTATS_MIB_FRAGOKS);
1022         consume_skb(skb);
1023         return err;
1024
1025 fail_toobig:
1026         if (skb->sk && dst_allfrag(skb_dst(skb)))
1027                 sk_gso_disable(skb->sk);
1028
1029         icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
1030         err = -EMSGSIZE;
1031
1032 fail:
1033         IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
1034                       IPSTATS_MIB_FRAGFAILS);
1035         kfree_skb(skb);
1036         return err;
1037 }
1038
1039 static inline int ip6_rt_check(const struct rt6key *rt_key,
1040                                const struct in6_addr *fl_addr,
1041                                const struct in6_addr *addr_cache)
1042 {
1043         return (rt_key->plen != 128 || !ipv6_addr_equal(fl_addr, &rt_key->addr)) &&
1044                 (!addr_cache || !ipv6_addr_equal(fl_addr, addr_cache));
1045 }
1046
1047 static struct dst_entry *ip6_sk_dst_check(struct sock *sk,
1048                                           struct dst_entry *dst,
1049                                           const struct flowi6 *fl6)
1050 {
1051         struct ipv6_pinfo *np = inet6_sk(sk);
1052         struct rt6_info *rt;
1053
1054         if (!dst)
1055                 goto out;
1056
1057         if (dst->ops->family != AF_INET6) {
1058                 dst_release(dst);
1059                 return NULL;
1060         }
1061
1062         rt = (struct rt6_info *)dst;
1063         /* Yes, checking route validity in not connected
1064          * case is not very simple. Take into account,
1065          * that we do not support routing by source, TOS,
1066          * and MSG_DONTROUTE            --ANK (980726)
1067          *
1068          * 1. ip6_rt_check(): If route was host route,
1069          *    check that cached destination is current.
1070          *    If it is network route, we still may
1071          *    check its validity using saved pointer
1072          *    to the last used address: daddr_cache.
1073          *    We do not want to save whole address now,
1074          *    (because main consumer of this service
1075          *    is tcp, which has not this problem),
1076          *    so that the last trick works only on connected
1077          *    sockets.
1078          * 2. oif also should be the same.
1079          */
1080         if (ip6_rt_check(&rt->rt6i_dst, &fl6->daddr, np->daddr_cache) ||
1081 #ifdef CONFIG_IPV6_SUBTREES
1082             ip6_rt_check(&rt->rt6i_src, &fl6->saddr, np->saddr_cache) ||
1083 #endif
1084            (fl6->flowi6_oif && fl6->flowi6_oif != dst->dev->ifindex)) {
1085                 dst_release(dst);
1086                 dst = NULL;
1087         }
1088
1089 out:
1090         return dst;
1091 }
1092
1093 static int ip6_dst_lookup_tail(struct net *net, const struct sock *sk,
1094                                struct dst_entry **dst, struct flowi6 *fl6)
1095 {
1096 #ifdef CONFIG_IPV6_OPTIMISTIC_DAD
1097         struct neighbour *n;
1098         struct rt6_info *rt;
1099 #endif
1100         int err;
1101         int flags = 0;
1102
1103         /* The correct way to handle this would be to do
1104          * ip6_route_get_saddr, and then ip6_route_output; however,
1105          * the route-specific preferred source forces the
1106          * ip6_route_output call _before_ ip6_route_get_saddr.
1107          *
1108          * In source specific routing (no src=any default route),
1109          * ip6_route_output will fail given src=any saddr, though, so
1110          * that's why we try it again later.
1111          */
1112         if (ipv6_addr_any(&fl6->saddr)) {
1113                 struct fib6_info *from;
1114                 struct rt6_info *rt;
1115
1116                 *dst = ip6_route_output(net, sk, fl6);
1117                 rt = (*dst)->error ? NULL : (struct rt6_info *)*dst;
1118
1119                 rcu_read_lock();
1120                 from = rt ? rcu_dereference(rt->from) : NULL;
1121                 err = ip6_route_get_saddr(net, from, &fl6->daddr,
1122                                           sk ? inet6_sk(sk)->srcprefs : 0,
1123                                           &fl6->saddr);
1124                 rcu_read_unlock();
1125
1126                 if (err)
1127                         goto out_err_release;
1128
1129                 /* If we had an erroneous initial result, pretend it
1130                  * never existed and let the SA-enabled version take
1131                  * over.
1132                  */
1133                 if ((*dst)->error) {
1134                         dst_release(*dst);
1135                         *dst = NULL;
1136                 }
1137
1138                 if (fl6->flowi6_oif)
1139                         flags |= RT6_LOOKUP_F_IFACE;
1140         }
1141
1142         if (!*dst)
1143                 *dst = ip6_route_output_flags(net, sk, fl6, flags);
1144
1145         err = (*dst)->error;
1146         if (err)
1147                 goto out_err_release;
1148
1149 #ifdef CONFIG_IPV6_OPTIMISTIC_DAD
1150         /*
1151          * Here if the dst entry we've looked up
1152          * has a neighbour entry that is in the INCOMPLETE
1153          * state and the src address from the flow is
1154          * marked as OPTIMISTIC, we release the found
1155          * dst entry and replace it instead with the
1156          * dst entry of the nexthop router
1157          */
1158         rt = (struct rt6_info *) *dst;
1159         rcu_read_lock();
1160         n = __ipv6_neigh_lookup_noref(rt->dst.dev,
1161                                       rt6_nexthop(rt, &fl6->daddr));
1162         err = n && !(READ_ONCE(n->nud_state) & NUD_VALID) ? -EINVAL : 0;
1163         rcu_read_unlock();
1164
1165         if (err) {
1166                 struct inet6_ifaddr *ifp;
1167                 struct flowi6 fl_gw6;
1168                 int redirect;
1169
1170                 ifp = ipv6_get_ifaddr(net, &fl6->saddr,
1171                                       (*dst)->dev, 1);
1172
1173                 redirect = (ifp && ifp->flags & IFA_F_OPTIMISTIC);
1174                 if (ifp)
1175                         in6_ifa_put(ifp);
1176
1177                 if (redirect) {
1178                         /*
1179                          * We need to get the dst entry for the
1180                          * default router instead
1181                          */
1182                         dst_release(*dst);
1183                         memcpy(&fl_gw6, fl6, sizeof(struct flowi6));
1184                         memset(&fl_gw6.daddr, 0, sizeof(struct in6_addr));
1185                         *dst = ip6_route_output(net, sk, &fl_gw6);
1186                         err = (*dst)->error;
1187                         if (err)
1188                                 goto out_err_release;
1189                 }
1190         }
1191 #endif
1192         if (ipv6_addr_v4mapped(&fl6->saddr) &&
1193             !(ipv6_addr_v4mapped(&fl6->daddr) || ipv6_addr_any(&fl6->daddr))) {
1194                 err = -EAFNOSUPPORT;
1195                 goto out_err_release;
1196         }
1197
1198         return 0;
1199
1200 out_err_release:
1201         dst_release(*dst);
1202         *dst = NULL;
1203
1204         if (err == -ENETUNREACH)
1205                 IP6_INC_STATS(net, NULL, IPSTATS_MIB_OUTNOROUTES);
1206         return err;
1207 }
1208
1209 /**
1210  *      ip6_dst_lookup - perform route lookup on flow
1211  *      @net: Network namespace to perform lookup in
1212  *      @sk: socket which provides route info
1213  *      @dst: pointer to dst_entry * for result
1214  *      @fl6: flow to lookup
1215  *
1216  *      This function performs a route lookup on the given flow.
1217  *
1218  *      It returns zero on success, or a standard errno code on error.
1219  */
1220 int ip6_dst_lookup(struct net *net, struct sock *sk, struct dst_entry **dst,
1221                    struct flowi6 *fl6)
1222 {
1223         *dst = NULL;
1224         return ip6_dst_lookup_tail(net, sk, dst, fl6);
1225 }
1226 EXPORT_SYMBOL_GPL(ip6_dst_lookup);
1227
1228 /**
1229  *      ip6_dst_lookup_flow - perform route lookup on flow with ipsec
1230  *      @net: Network namespace to perform lookup in
1231  *      @sk: socket which provides route info
1232  *      @fl6: flow to lookup
1233  *      @final_dst: final destination address for ipsec lookup
1234  *
1235  *      This function performs a route lookup on the given flow.
1236  *
1237  *      It returns a valid dst pointer on success, or a pointer encoded
1238  *      error code.
1239  */
1240 struct dst_entry *ip6_dst_lookup_flow(struct net *net, const struct sock *sk, struct flowi6 *fl6,
1241                                       const struct in6_addr *final_dst)
1242 {
1243         struct dst_entry *dst = NULL;
1244         int err;
1245
1246         err = ip6_dst_lookup_tail(net, sk, &dst, fl6);
1247         if (err)
1248                 return ERR_PTR(err);
1249         if (final_dst)
1250                 fl6->daddr = *final_dst;
1251
1252         return xfrm_lookup_route(net, dst, flowi6_to_flowi(fl6), sk, 0);
1253 }
1254 EXPORT_SYMBOL_GPL(ip6_dst_lookup_flow);
1255
1256 /**
1257  *      ip6_sk_dst_lookup_flow - perform socket cached route lookup on flow
1258  *      @sk: socket which provides the dst cache and route info
1259  *      @fl6: flow to lookup
1260  *      @final_dst: final destination address for ipsec lookup
1261  *      @connected: whether @sk is connected or not
1262  *
1263  *      This function performs a route lookup on the given flow with the
1264  *      possibility of using the cached route in the socket if it is valid.
1265  *      It will take the socket dst lock when operating on the dst cache.
1266  *      As a result, this function can only be used in process context.
1267  *
1268  *      In addition, for a connected socket, cache the dst in the socket
1269  *      if the current cache is not valid.
1270  *
1271  *      It returns a valid dst pointer on success, or a pointer encoded
1272  *      error code.
1273  */
1274 struct dst_entry *ip6_sk_dst_lookup_flow(struct sock *sk, struct flowi6 *fl6,
1275                                          const struct in6_addr *final_dst,
1276                                          bool connected)
1277 {
1278         struct dst_entry *dst = sk_dst_check(sk, inet6_sk(sk)->dst_cookie);
1279
1280         dst = ip6_sk_dst_check(sk, dst, fl6);
1281         if (dst)
1282                 return dst;
1283
1284         dst = ip6_dst_lookup_flow(sock_net(sk), sk, fl6, final_dst);
1285         if (connected && !IS_ERR(dst))
1286                 ip6_sk_dst_store_flow(sk, dst_clone(dst), fl6);
1287
1288         return dst;
1289 }
1290 EXPORT_SYMBOL_GPL(ip6_sk_dst_lookup_flow);
1291
1292 /**
1293  *      ip6_dst_lookup_tunnel - perform route lookup on tunnel
1294  *      @skb: Packet for which lookup is done
1295  *      @dev: Tunnel device
1296  *      @net: Network namespace of tunnel device
1297  *      @sock: Socket which provides route info
1298  *      @saddr: Memory to store the src ip address
1299  *      @info: Tunnel information
1300  *      @protocol: IP protocol
1301  *      @use_cache: Flag to enable cache usage
1302  *      This function performs a route lookup on a tunnel
1303  *
1304  *      It returns a valid dst pointer and stores src address to be used in
1305  *      tunnel in param saddr on success, else a pointer encoded error code.
1306  */
1307
1308 struct dst_entry *ip6_dst_lookup_tunnel(struct sk_buff *skb,
1309                                         struct net_device *dev,
1310                                         struct net *net,
1311                                         struct socket *sock,
1312                                         struct in6_addr *saddr,
1313                                         const struct ip_tunnel_info *info,
1314                                         u8 protocol,
1315                                         bool use_cache)
1316 {
1317         struct dst_entry *dst = NULL;
1318 #ifdef CONFIG_DST_CACHE
1319         struct dst_cache *dst_cache;
1320 #endif
1321         struct flowi6 fl6;
1322         __u8 prio;
1323
1324 #ifdef CONFIG_DST_CACHE
1325         dst_cache = (struct dst_cache *)&info->dst_cache;
1326         if (use_cache) {
1327                 dst = dst_cache_get_ip6(dst_cache, saddr);
1328                 if (dst)
1329                         return dst;
1330         }
1331 #endif
1332         memset(&fl6, 0, sizeof(fl6));
1333         fl6.flowi6_mark = skb->mark;
1334         fl6.flowi6_proto = protocol;
1335         fl6.daddr = info->key.u.ipv6.dst;
1336         fl6.saddr = info->key.u.ipv6.src;
1337         prio = info->key.tos;
1338         fl6.flowlabel = ip6_make_flowinfo(prio, info->key.label);
1339
1340         dst = ipv6_stub->ipv6_dst_lookup_flow(net, sock->sk, &fl6,
1341                                               NULL);
1342         if (IS_ERR(dst)) {
1343                 netdev_dbg(dev, "no route to %pI6\n", &fl6.daddr);
1344                 return ERR_PTR(-ENETUNREACH);
1345         }
1346         if (dst->dev == dev) { /* is this necessary? */
1347                 netdev_dbg(dev, "circular route to %pI6\n", &fl6.daddr);
1348                 dst_release(dst);
1349                 return ERR_PTR(-ELOOP);
1350         }
1351 #ifdef CONFIG_DST_CACHE
1352         if (use_cache)
1353                 dst_cache_set_ip6(dst_cache, dst, &fl6.saddr);
1354 #endif
1355         *saddr = fl6.saddr;
1356         return dst;
1357 }
1358 EXPORT_SYMBOL_GPL(ip6_dst_lookup_tunnel);
1359
1360 static inline struct ipv6_opt_hdr *ip6_opt_dup(struct ipv6_opt_hdr *src,
1361                                                gfp_t gfp)
1362 {
1363         return src ? kmemdup(src, (src->hdrlen + 1) * 8, gfp) : NULL;
1364 }
1365
1366 static inline struct ipv6_rt_hdr *ip6_rthdr_dup(struct ipv6_rt_hdr *src,
1367                                                 gfp_t gfp)
1368 {
1369         return src ? kmemdup(src, (src->hdrlen + 1) * 8, gfp) : NULL;
1370 }
1371
1372 static void ip6_append_data_mtu(unsigned int *mtu,
1373                                 int *maxfraglen,
1374                                 unsigned int fragheaderlen,
1375                                 struct sk_buff *skb,
1376                                 struct rt6_info *rt,
1377                                 unsigned int orig_mtu)
1378 {
1379         if (!(rt->dst.flags & DST_XFRM_TUNNEL)) {
1380                 if (!skb) {
1381                         /* first fragment, reserve header_len */
1382                         *mtu = orig_mtu - rt->dst.header_len;
1383
1384                 } else {
1385                         /*
1386                          * this fragment is not first, the headers
1387                          * space is regarded as data space.
1388                          */
1389                         *mtu = orig_mtu;
1390                 }
1391                 *maxfraglen = ((*mtu - fragheaderlen) & ~7)
1392                               + fragheaderlen - sizeof(struct frag_hdr);
1393         }
1394 }
1395
1396 static int ip6_setup_cork(struct sock *sk, struct inet_cork_full *cork,
1397                           struct inet6_cork *v6_cork, struct ipcm6_cookie *ipc6,
1398                           struct rt6_info *rt)
1399 {
1400         struct ipv6_pinfo *np = inet6_sk(sk);
1401         unsigned int mtu;
1402         struct ipv6_txoptions *nopt, *opt = ipc6->opt;
1403
1404         /* callers pass dst together with a reference, set it first so
1405          * ip6_cork_release() can put it down even in case of an error.
1406          */
1407         cork->base.dst = &rt->dst;
1408
1409         /*
1410          * setup for corking
1411          */
1412         if (opt) {
1413                 if (WARN_ON(v6_cork->opt))
1414                         return -EINVAL;
1415
1416                 nopt = v6_cork->opt = kzalloc(sizeof(*opt), sk->sk_allocation);
1417                 if (unlikely(!nopt))
1418                         return -ENOBUFS;
1419
1420                 nopt->tot_len = sizeof(*opt);
1421                 nopt->opt_flen = opt->opt_flen;
1422                 nopt->opt_nflen = opt->opt_nflen;
1423
1424                 nopt->dst0opt = ip6_opt_dup(opt->dst0opt, sk->sk_allocation);
1425                 if (opt->dst0opt && !nopt->dst0opt)
1426                         return -ENOBUFS;
1427
1428                 nopt->dst1opt = ip6_opt_dup(opt->dst1opt, sk->sk_allocation);
1429                 if (opt->dst1opt && !nopt->dst1opt)
1430                         return -ENOBUFS;
1431
1432                 nopt->hopopt = ip6_opt_dup(opt->hopopt, sk->sk_allocation);
1433                 if (opt->hopopt && !nopt->hopopt)
1434                         return -ENOBUFS;
1435
1436                 nopt->srcrt = ip6_rthdr_dup(opt->srcrt, sk->sk_allocation);
1437                 if (opt->srcrt && !nopt->srcrt)
1438                         return -ENOBUFS;
1439
1440                 /* need source address above miyazawa*/
1441         }
1442         v6_cork->hop_limit = ipc6->hlimit;
1443         v6_cork->tclass = ipc6->tclass;
1444         if (rt->dst.flags & DST_XFRM_TUNNEL)
1445                 mtu = np->pmtudisc >= IPV6_PMTUDISC_PROBE ?
1446                       READ_ONCE(rt->dst.dev->mtu) : dst_mtu(&rt->dst);
1447         else
1448                 mtu = np->pmtudisc >= IPV6_PMTUDISC_PROBE ?
1449                         READ_ONCE(rt->dst.dev->mtu) : dst_mtu(xfrm_dst_path(&rt->dst));
1450         if (np->frag_size < mtu) {
1451                 if (np->frag_size)
1452                         mtu = np->frag_size;
1453         }
1454         cork->base.fragsize = mtu;
1455         cork->base.gso_size = ipc6->gso_size;
1456         cork->base.tx_flags = 0;
1457         cork->base.mark = ipc6->sockc.mark;
1458         sock_tx_timestamp(sk, ipc6->sockc.tsflags, &cork->base.tx_flags);
1459
1460         if (dst_allfrag(xfrm_dst_path(&rt->dst)))
1461                 cork->base.flags |= IPCORK_ALLFRAG;
1462         cork->base.length = 0;
1463
1464         cork->base.transmit_time = ipc6->sockc.transmit_time;
1465
1466         return 0;
1467 }
1468
1469 static int __ip6_append_data(struct sock *sk,
1470                              struct sk_buff_head *queue,
1471                              struct inet_cork_full *cork_full,
1472                              struct inet6_cork *v6_cork,
1473                              struct page_frag *pfrag,
1474                              int getfrag(void *from, char *to, int offset,
1475                                          int len, int odd, struct sk_buff *skb),
1476                              void *from, size_t length, int transhdrlen,
1477                              unsigned int flags, struct ipcm6_cookie *ipc6)
1478 {
1479         struct sk_buff *skb, *skb_prev = NULL;
1480         struct inet_cork *cork = &cork_full->base;
1481         struct flowi6 *fl6 = &cork_full->fl.u.ip6;
1482         unsigned int maxfraglen, fragheaderlen, mtu, orig_mtu, pmtu;
1483         struct ubuf_info *uarg = NULL;
1484         int exthdrlen = 0;
1485         int dst_exthdrlen = 0;
1486         int hh_len;
1487         int copy;
1488         int err;
1489         int offset = 0;
1490         bool zc = false;
1491         u32 tskey = 0;
1492         struct rt6_info *rt = (struct rt6_info *)cork->dst;
1493         struct ipv6_txoptions *opt = v6_cork->opt;
1494         int csummode = CHECKSUM_NONE;
1495         unsigned int maxnonfragsize, headersize;
1496         unsigned int wmem_alloc_delta = 0;
1497         bool paged, extra_uref = false;
1498
1499         skb = skb_peek_tail(queue);
1500         if (!skb) {
1501                 exthdrlen = opt ? opt->opt_flen : 0;
1502                 dst_exthdrlen = rt->dst.header_len - rt->rt6i_nfheader_len;
1503         }
1504
1505         paged = !!cork->gso_size;
1506         mtu = cork->gso_size ? IP6_MAX_MTU : cork->fragsize;
1507         orig_mtu = mtu;
1508
1509         if (cork->tx_flags & SKBTX_ANY_TSTAMP &&
1510             READ_ONCE(sk->sk_tsflags) & SOF_TIMESTAMPING_OPT_ID)
1511                 tskey = atomic_inc_return(&sk->sk_tskey) - 1;
1512
1513         hh_len = LL_RESERVED_SPACE(rt->dst.dev);
1514
1515         fragheaderlen = sizeof(struct ipv6hdr) + rt->rt6i_nfheader_len +
1516                         (opt ? opt->opt_nflen : 0);
1517
1518         headersize = sizeof(struct ipv6hdr) +
1519                      (opt ? opt->opt_flen + opt->opt_nflen : 0) +
1520                      (dst_allfrag(&rt->dst) ?
1521                       sizeof(struct frag_hdr) : 0) +
1522                      rt->rt6i_nfheader_len;
1523
1524         if (mtu <= fragheaderlen ||
1525             ((mtu - fragheaderlen) & ~7) + fragheaderlen <= sizeof(struct frag_hdr))
1526                 goto emsgsize;
1527
1528         maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen -
1529                      sizeof(struct frag_hdr);
1530
1531         /* as per RFC 7112 section 5, the entire IPv6 Header Chain must fit
1532          * the first fragment
1533          */
1534         if (headersize + transhdrlen > mtu)
1535                 goto emsgsize;
1536
1537         if (cork->length + length > mtu - headersize && ipc6->dontfrag &&
1538             (sk->sk_protocol == IPPROTO_UDP ||
1539              sk->sk_protocol == IPPROTO_ICMPV6 ||
1540              sk->sk_protocol == IPPROTO_RAW)) {
1541                 ipv6_local_rxpmtu(sk, fl6, mtu - headersize +
1542                                 sizeof(struct ipv6hdr));
1543                 goto emsgsize;
1544         }
1545
1546         if (ip6_sk_ignore_df(sk))
1547                 maxnonfragsize = sizeof(struct ipv6hdr) + IPV6_MAXPLEN;
1548         else
1549                 maxnonfragsize = mtu;
1550
1551         if (cork->length + length > maxnonfragsize - headersize) {
1552 emsgsize:
1553                 pmtu = max_t(int, mtu - headersize + sizeof(struct ipv6hdr), 0);
1554                 ipv6_local_error(sk, EMSGSIZE, fl6, pmtu);
1555                 return -EMSGSIZE;
1556         }
1557
1558         /* CHECKSUM_PARTIAL only with no extension headers and when
1559          * we are not going to fragment
1560          */
1561         if (transhdrlen && sk->sk_protocol == IPPROTO_UDP &&
1562             headersize == sizeof(struct ipv6hdr) &&
1563             length <= mtu - headersize &&
1564             (!(flags & MSG_MORE) || cork->gso_size) &&
1565             rt->dst.dev->features & (NETIF_F_IPV6_CSUM | NETIF_F_HW_CSUM))
1566                 csummode = CHECKSUM_PARTIAL;
1567
1568         if ((flags & MSG_ZEROCOPY) && length) {
1569                 struct msghdr *msg = from;
1570
1571                 if (getfrag == ip_generic_getfrag && msg->msg_ubuf) {
1572                         if (skb_zcopy(skb) && msg->msg_ubuf != skb_zcopy(skb))
1573                                 return -EINVAL;
1574
1575                         /* Leave uarg NULL if can't zerocopy, callers should
1576                          * be able to handle it.
1577                          */
1578                         if ((rt->dst.dev->features & NETIF_F_SG) &&
1579                             csummode == CHECKSUM_PARTIAL) {
1580                                 paged = true;
1581                                 zc = true;
1582                                 uarg = msg->msg_ubuf;
1583                         }
1584                 } else if (sock_flag(sk, SOCK_ZEROCOPY)) {
1585                         uarg = msg_zerocopy_realloc(sk, length, skb_zcopy(skb));
1586                         if (!uarg)
1587                                 return -ENOBUFS;
1588                         extra_uref = !skb_zcopy(skb);   /* only ref on new uarg */
1589                         if (rt->dst.dev->features & NETIF_F_SG &&
1590                             csummode == CHECKSUM_PARTIAL) {
1591                                 paged = true;
1592                                 zc = true;
1593                         } else {
1594                                 uarg_to_msgzc(uarg)->zerocopy = 0;
1595                                 skb_zcopy_set(skb, uarg, &extra_uref);
1596                         }
1597                 }
1598         } else if ((flags & MSG_SPLICE_PAGES) && length) {
1599                 if (inet_test_bit(HDRINCL, sk))
1600                         return -EPERM;
1601                 if (rt->dst.dev->features & NETIF_F_SG &&
1602                     getfrag == ip_generic_getfrag)
1603                         /* We need an empty buffer to attach stuff to */
1604                         paged = true;
1605                 else
1606                         flags &= ~MSG_SPLICE_PAGES;
1607         }
1608
1609         /*
1610          * Let's try using as much space as possible.
1611          * Use MTU if total length of the message fits into the MTU.
1612          * Otherwise, we need to reserve fragment header and
1613          * fragment alignment (= 8-15 octects, in total).
1614          *
1615          * Note that we may need to "move" the data from the tail
1616          * of the buffer to the new fragment when we split
1617          * the message.
1618          *
1619          * FIXME: It may be fragmented into multiple chunks
1620          *        at once if non-fragmentable extension headers
1621          *        are too large.
1622          * --yoshfuji
1623          */
1624
1625         cork->length += length;
1626         if (!skb)
1627                 goto alloc_new_skb;
1628
1629         while (length > 0) {
1630                 /* Check if the remaining data fits into current packet. */
1631                 copy = (cork->length <= mtu && !(cork->flags & IPCORK_ALLFRAG) ? mtu : maxfraglen) - skb->len;
1632                 if (copy < length)
1633                         copy = maxfraglen - skb->len;
1634
1635                 if (copy <= 0) {
1636                         char *data;
1637                         unsigned int datalen;
1638                         unsigned int fraglen;
1639                         unsigned int fraggap;
1640                         unsigned int alloclen, alloc_extra;
1641                         unsigned int pagedlen;
1642 alloc_new_skb:
1643                         /* There's no room in the current skb */
1644                         if (skb)
1645                                 fraggap = skb->len - maxfraglen;
1646                         else
1647                                 fraggap = 0;
1648                         /* update mtu and maxfraglen if necessary */
1649                         if (!skb || !skb_prev)
1650                                 ip6_append_data_mtu(&mtu, &maxfraglen,
1651                                                     fragheaderlen, skb, rt,
1652                                                     orig_mtu);
1653
1654                         skb_prev = skb;
1655
1656                         /*
1657                          * If remaining data exceeds the mtu,
1658                          * we know we need more fragment(s).
1659                          */
1660                         datalen = length + fraggap;
1661
1662                         if (datalen > (cork->length <= mtu && !(cork->flags & IPCORK_ALLFRAG) ? mtu : maxfraglen) - fragheaderlen)
1663                                 datalen = maxfraglen - fragheaderlen - rt->dst.trailer_len;
1664                         fraglen = datalen + fragheaderlen;
1665                         pagedlen = 0;
1666
1667                         alloc_extra = hh_len;
1668                         alloc_extra += dst_exthdrlen;
1669                         alloc_extra += rt->dst.trailer_len;
1670
1671                         /* We just reserve space for fragment header.
1672                          * Note: this may be overallocation if the message
1673                          * (without MSG_MORE) fits into the MTU.
1674                          */
1675                         alloc_extra += sizeof(struct frag_hdr);
1676
1677                         if ((flags & MSG_MORE) &&
1678                             !(rt->dst.dev->features&NETIF_F_SG))
1679                                 alloclen = mtu;
1680                         else if (!paged &&
1681                                  (fraglen + alloc_extra < SKB_MAX_ALLOC ||
1682                                   !(rt->dst.dev->features & NETIF_F_SG)))
1683                                 alloclen = fraglen;
1684                         else {
1685                                 alloclen = fragheaderlen + transhdrlen;
1686                                 pagedlen = datalen - transhdrlen;
1687                         }
1688                         alloclen += alloc_extra;
1689
1690                         if (datalen != length + fraggap) {
1691                                 /*
1692                                  * this is not the last fragment, the trailer
1693                                  * space is regarded as data space.
1694                                  */
1695                                 datalen += rt->dst.trailer_len;
1696                         }
1697
1698                         fraglen = datalen + fragheaderlen;
1699
1700                         copy = datalen - transhdrlen - fraggap - pagedlen;
1701                         /* [!] NOTE: copy may be negative if pagedlen>0
1702                          * because then the equation may reduces to -fraggap.
1703                          */
1704                         if (copy < 0 && !(flags & MSG_SPLICE_PAGES)) {
1705                                 err = -EINVAL;
1706                                 goto error;
1707                         }
1708                         if (transhdrlen) {
1709                                 skb = sock_alloc_send_skb(sk, alloclen,
1710                                                 (flags & MSG_DONTWAIT), &err);
1711                         } else {
1712                                 skb = NULL;
1713                                 if (refcount_read(&sk->sk_wmem_alloc) + wmem_alloc_delta <=
1714                                     2 * sk->sk_sndbuf)
1715                                         skb = alloc_skb(alloclen,
1716                                                         sk->sk_allocation);
1717                                 if (unlikely(!skb))
1718                                         err = -ENOBUFS;
1719                         }
1720                         if (!skb)
1721                                 goto error;
1722                         /*
1723                          *      Fill in the control structures
1724                          */
1725                         skb->protocol = htons(ETH_P_IPV6);
1726                         skb->ip_summed = csummode;
1727                         skb->csum = 0;
1728                         /* reserve for fragmentation and ipsec header */
1729                         skb_reserve(skb, hh_len + sizeof(struct frag_hdr) +
1730                                     dst_exthdrlen);
1731
1732                         /*
1733                          *      Find where to start putting bytes
1734                          */
1735                         data = skb_put(skb, fraglen - pagedlen);
1736                         skb_set_network_header(skb, exthdrlen);
1737                         data += fragheaderlen;
1738                         skb->transport_header = (skb->network_header +
1739                                                  fragheaderlen);
1740                         if (fraggap) {
1741                                 skb->csum = skb_copy_and_csum_bits(
1742                                         skb_prev, maxfraglen,
1743                                         data + transhdrlen, fraggap);
1744                                 skb_prev->csum = csum_sub(skb_prev->csum,
1745                                                           skb->csum);
1746                                 data += fraggap;
1747                                 pskb_trim_unique(skb_prev, maxfraglen);
1748                         }
1749                         if (copy > 0 &&
1750                             getfrag(from, data + transhdrlen, offset,
1751                                     copy, fraggap, skb) < 0) {
1752                                 err = -EFAULT;
1753                                 kfree_skb(skb);
1754                                 goto error;
1755                         } else if (flags & MSG_SPLICE_PAGES) {
1756                                 copy = 0;
1757                         }
1758
1759                         offset += copy;
1760                         length -= copy + transhdrlen;
1761                         transhdrlen = 0;
1762                         exthdrlen = 0;
1763                         dst_exthdrlen = 0;
1764
1765                         /* Only the initial fragment is time stamped */
1766                         skb_shinfo(skb)->tx_flags = cork->tx_flags;
1767                         cork->tx_flags = 0;
1768                         skb_shinfo(skb)->tskey = tskey;
1769                         tskey = 0;
1770                         skb_zcopy_set(skb, uarg, &extra_uref);
1771
1772                         if ((flags & MSG_CONFIRM) && !skb_prev)
1773                                 skb_set_dst_pending_confirm(skb, 1);
1774
1775                         /*
1776                          * Put the packet on the pending queue
1777                          */
1778                         if (!skb->destructor) {
1779                                 skb->destructor = sock_wfree;
1780                                 skb->sk = sk;
1781                                 wmem_alloc_delta += skb->truesize;
1782                         }
1783                         __skb_queue_tail(queue, skb);
1784                         continue;
1785                 }
1786
1787                 if (copy > length)
1788                         copy = length;
1789
1790                 if (!(rt->dst.dev->features&NETIF_F_SG) &&
1791                     skb_tailroom(skb) >= copy) {
1792                         unsigned int off;
1793
1794                         off = skb->len;
1795                         if (getfrag(from, skb_put(skb, copy),
1796                                                 offset, copy, off, skb) < 0) {
1797                                 __skb_trim(skb, off);
1798                                 err = -EFAULT;
1799                                 goto error;
1800                         }
1801                 } else if (flags & MSG_SPLICE_PAGES) {
1802                         struct msghdr *msg = from;
1803
1804                         err = -EIO;
1805                         if (WARN_ON_ONCE(copy > msg->msg_iter.count))
1806                                 goto error;
1807
1808                         err = skb_splice_from_iter(skb, &msg->msg_iter, copy,
1809                                                    sk->sk_allocation);
1810                         if (err < 0)
1811                                 goto error;
1812                         copy = err;
1813                         wmem_alloc_delta += copy;
1814                 } else if (!zc) {
1815                         int i = skb_shinfo(skb)->nr_frags;
1816
1817                         err = -ENOMEM;
1818                         if (!sk_page_frag_refill(sk, pfrag))
1819                                 goto error;
1820
1821                         skb_zcopy_downgrade_managed(skb);
1822                         if (!skb_can_coalesce(skb, i, pfrag->page,
1823                                               pfrag->offset)) {
1824                                 err = -EMSGSIZE;
1825                                 if (i == MAX_SKB_FRAGS)
1826                                         goto error;
1827
1828                                 __skb_fill_page_desc(skb, i, pfrag->page,
1829                                                      pfrag->offset, 0);
1830                                 skb_shinfo(skb)->nr_frags = ++i;
1831                                 get_page(pfrag->page);
1832                         }
1833                         copy = min_t(int, copy, pfrag->size - pfrag->offset);
1834                         if (getfrag(from,
1835                                     page_address(pfrag->page) + pfrag->offset,
1836                                     offset, copy, skb->len, skb) < 0)
1837                                 goto error_efault;
1838
1839                         pfrag->offset += copy;
1840                         skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy);
1841                         skb->len += copy;
1842                         skb->data_len += copy;
1843                         skb->truesize += copy;
1844                         wmem_alloc_delta += copy;
1845                 } else {
1846                         err = skb_zerocopy_iter_dgram(skb, from, copy);
1847                         if (err < 0)
1848                                 goto error;
1849                 }
1850                 offset += copy;
1851                 length -= copy;
1852         }
1853
1854         if (wmem_alloc_delta)
1855                 refcount_add(wmem_alloc_delta, &sk->sk_wmem_alloc);
1856         return 0;
1857
1858 error_efault:
1859         err = -EFAULT;
1860 error:
1861         net_zcopy_put_abort(uarg, extra_uref);
1862         cork->length -= length;
1863         IP6_INC_STATS(sock_net(sk), rt->rt6i_idev, IPSTATS_MIB_OUTDISCARDS);
1864         refcount_add(wmem_alloc_delta, &sk->sk_wmem_alloc);
1865         return err;
1866 }
1867
1868 int ip6_append_data(struct sock *sk,
1869                     int getfrag(void *from, char *to, int offset, int len,
1870                                 int odd, struct sk_buff *skb),
1871                     void *from, size_t length, int transhdrlen,
1872                     struct ipcm6_cookie *ipc6, struct flowi6 *fl6,
1873                     struct rt6_info *rt, unsigned int flags)
1874 {
1875         struct inet_sock *inet = inet_sk(sk);
1876         struct ipv6_pinfo *np = inet6_sk(sk);
1877         int exthdrlen;
1878         int err;
1879
1880         if (flags&MSG_PROBE)
1881                 return 0;
1882         if (skb_queue_empty(&sk->sk_write_queue)) {
1883                 /*
1884                  * setup for corking
1885                  */
1886                 dst_hold(&rt->dst);
1887                 err = ip6_setup_cork(sk, &inet->cork, &np->cork,
1888                                      ipc6, rt);
1889                 if (err)
1890                         return err;
1891
1892                 inet->cork.fl.u.ip6 = *fl6;
1893                 exthdrlen = (ipc6->opt ? ipc6->opt->opt_flen : 0);
1894                 length += exthdrlen;
1895                 transhdrlen += exthdrlen;
1896         } else {
1897                 transhdrlen = 0;
1898         }
1899
1900         return __ip6_append_data(sk, &sk->sk_write_queue, &inet->cork,
1901                                  &np->cork, sk_page_frag(sk), getfrag,
1902                                  from, length, transhdrlen, flags, ipc6);
1903 }
1904 EXPORT_SYMBOL_GPL(ip6_append_data);
1905
1906 static void ip6_cork_steal_dst(struct sk_buff *skb, struct inet_cork_full *cork)
1907 {
1908         struct dst_entry *dst = cork->base.dst;
1909
1910         cork->base.dst = NULL;
1911         cork->base.flags &= ~IPCORK_ALLFRAG;
1912         skb_dst_set(skb, dst);
1913 }
1914
1915 static void ip6_cork_release(struct inet_cork_full *cork,
1916                              struct inet6_cork *v6_cork)
1917 {
1918         if (v6_cork->opt) {
1919                 struct ipv6_txoptions *opt = v6_cork->opt;
1920
1921                 kfree(opt->dst0opt);
1922                 kfree(opt->dst1opt);
1923                 kfree(opt->hopopt);
1924                 kfree(opt->srcrt);
1925                 kfree(opt);
1926                 v6_cork->opt = NULL;
1927         }
1928
1929         if (cork->base.dst) {
1930                 dst_release(cork->base.dst);
1931                 cork->base.dst = NULL;
1932                 cork->base.flags &= ~IPCORK_ALLFRAG;
1933         }
1934 }
1935
1936 struct sk_buff *__ip6_make_skb(struct sock *sk,
1937                                struct sk_buff_head *queue,
1938                                struct inet_cork_full *cork,
1939                                struct inet6_cork *v6_cork)
1940 {
1941         struct sk_buff *skb, *tmp_skb;
1942         struct sk_buff **tail_skb;
1943         struct in6_addr *final_dst;
1944         struct ipv6_pinfo *np = inet6_sk(sk);
1945         struct net *net = sock_net(sk);
1946         struct ipv6hdr *hdr;
1947         struct ipv6_txoptions *opt = v6_cork->opt;
1948         struct rt6_info *rt = (struct rt6_info *)cork->base.dst;
1949         struct flowi6 *fl6 = &cork->fl.u.ip6;
1950         unsigned char proto = fl6->flowi6_proto;
1951
1952         skb = __skb_dequeue(queue);
1953         if (!skb)
1954                 goto out;
1955         tail_skb = &(skb_shinfo(skb)->frag_list);
1956
1957         /* move skb->data to ip header from ext header */
1958         if (skb->data < skb_network_header(skb))
1959                 __skb_pull(skb, skb_network_offset(skb));
1960         while ((tmp_skb = __skb_dequeue(queue)) != NULL) {
1961                 __skb_pull(tmp_skb, skb_network_header_len(skb));
1962                 *tail_skb = tmp_skb;
1963                 tail_skb = &(tmp_skb->next);
1964                 skb->len += tmp_skb->len;
1965                 skb->data_len += tmp_skb->len;
1966                 skb->truesize += tmp_skb->truesize;
1967                 tmp_skb->destructor = NULL;
1968                 tmp_skb->sk = NULL;
1969         }
1970
1971         /* Allow local fragmentation. */
1972         skb->ignore_df = ip6_sk_ignore_df(sk);
1973         __skb_pull(skb, skb_network_header_len(skb));
1974
1975         final_dst = &fl6->daddr;
1976         if (opt && opt->opt_flen)
1977                 ipv6_push_frag_opts(skb, opt, &proto);
1978         if (opt && opt->opt_nflen)
1979                 ipv6_push_nfrag_opts(skb, opt, &proto, &final_dst, &fl6->saddr);
1980
1981         skb_push(skb, sizeof(struct ipv6hdr));
1982         skb_reset_network_header(skb);
1983         hdr = ipv6_hdr(skb);
1984
1985         ip6_flow_hdr(hdr, v6_cork->tclass,
1986                      ip6_make_flowlabel(net, skb, fl6->flowlabel,
1987                                         ip6_autoflowlabel(net, np), fl6));
1988         hdr->hop_limit = v6_cork->hop_limit;
1989         hdr->nexthdr = proto;
1990         hdr->saddr = fl6->saddr;
1991         hdr->daddr = *final_dst;
1992
1993         skb->priority = sk->sk_priority;
1994         skb->mark = cork->base.mark;
1995         skb->tstamp = cork->base.transmit_time;
1996
1997         ip6_cork_steal_dst(skb, cork);
1998         IP6_UPD_PO_STATS(net, rt->rt6i_idev, IPSTATS_MIB_OUT, skb->len);
1999         if (proto == IPPROTO_ICMPV6) {
2000                 struct inet6_dev *idev = ip6_dst_idev(skb_dst(skb));
2001                 u8 icmp6_type;
2002
2003                 if (sk->sk_socket->type == SOCK_RAW &&
2004                    !inet_test_bit(HDRINCL, sk))
2005                         icmp6_type = fl6->fl6_icmp_type;
2006                 else
2007                         icmp6_type = icmp6_hdr(skb)->icmp6_type;
2008                 ICMP6MSGOUT_INC_STATS(net, idev, icmp6_type);
2009                 ICMP6_INC_STATS(net, idev, ICMP6_MIB_OUTMSGS);
2010         }
2011
2012         ip6_cork_release(cork, v6_cork);
2013 out:
2014         return skb;
2015 }
2016
2017 int ip6_send_skb(struct sk_buff *skb)
2018 {
2019         struct net *net = sock_net(skb->sk);
2020         struct rt6_info *rt = (struct rt6_info *)skb_dst(skb);
2021         int err;
2022
2023         err = ip6_local_out(net, skb->sk, skb);
2024         if (err) {
2025                 if (err > 0)
2026                         err = net_xmit_errno(err);
2027                 if (err)
2028                         IP6_INC_STATS(net, rt->rt6i_idev,
2029                                       IPSTATS_MIB_OUTDISCARDS);
2030         }
2031
2032         return err;
2033 }
2034
2035 int ip6_push_pending_frames(struct sock *sk)
2036 {
2037         struct sk_buff *skb;
2038
2039         skb = ip6_finish_skb(sk);
2040         if (!skb)
2041                 return 0;
2042
2043         return ip6_send_skb(skb);
2044 }
2045 EXPORT_SYMBOL_GPL(ip6_push_pending_frames);
2046
2047 static void __ip6_flush_pending_frames(struct sock *sk,
2048                                        struct sk_buff_head *queue,
2049                                        struct inet_cork_full *cork,
2050                                        struct inet6_cork *v6_cork)
2051 {
2052         struct sk_buff *skb;
2053
2054         while ((skb = __skb_dequeue_tail(queue)) != NULL) {
2055                 if (skb_dst(skb))
2056                         IP6_INC_STATS(sock_net(sk), ip6_dst_idev(skb_dst(skb)),
2057                                       IPSTATS_MIB_OUTDISCARDS);
2058                 kfree_skb(skb);
2059         }
2060
2061         ip6_cork_release(cork, v6_cork);
2062 }
2063
2064 void ip6_flush_pending_frames(struct sock *sk)
2065 {
2066         __ip6_flush_pending_frames(sk, &sk->sk_write_queue,
2067                                    &inet_sk(sk)->cork, &inet6_sk(sk)->cork);
2068 }
2069 EXPORT_SYMBOL_GPL(ip6_flush_pending_frames);
2070
2071 struct sk_buff *ip6_make_skb(struct sock *sk,
2072                              int getfrag(void *from, char *to, int offset,
2073                                          int len, int odd, struct sk_buff *skb),
2074                              void *from, size_t length, int transhdrlen,
2075                              struct ipcm6_cookie *ipc6, struct rt6_info *rt,
2076                              unsigned int flags, struct inet_cork_full *cork)
2077 {
2078         struct inet6_cork v6_cork;
2079         struct sk_buff_head queue;
2080         int exthdrlen = (ipc6->opt ? ipc6->opt->opt_flen : 0);
2081         int err;
2082
2083         if (flags & MSG_PROBE) {
2084                 dst_release(&rt->dst);
2085                 return NULL;
2086         }
2087
2088         __skb_queue_head_init(&queue);
2089
2090         cork->base.flags = 0;
2091         cork->base.addr = 0;
2092         cork->base.opt = NULL;
2093         v6_cork.opt = NULL;
2094         err = ip6_setup_cork(sk, cork, &v6_cork, ipc6, rt);
2095         if (err) {
2096                 ip6_cork_release(cork, &v6_cork);
2097                 return ERR_PTR(err);
2098         }
2099         if (ipc6->dontfrag < 0)
2100                 ipc6->dontfrag = inet6_sk(sk)->dontfrag;
2101
2102         err = __ip6_append_data(sk, &queue, cork, &v6_cork,
2103                                 &current->task_frag, getfrag, from,
2104                                 length + exthdrlen, transhdrlen + exthdrlen,
2105                                 flags, ipc6);
2106         if (err) {
2107                 __ip6_flush_pending_frames(sk, &queue, cork, &v6_cork);
2108                 return ERR_PTR(err);
2109         }
2110
2111         return __ip6_make_skb(sk, &queue, cork, &v6_cork);
2112 }