linux/net/xfrm/xfrm_output.c
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   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 * xfrm_output.c - Common IPsec encapsulation code.
   4 *
   5 * Copyright (c) 2007 Herbert Xu <herbert@gondor.apana.org.au>
   6 */
   7
   8#include <linux/errno.h>
   9#include <linux/module.h>
  10#include <linux/netdevice.h>
  11#include <linux/netfilter.h>
  12#include <linux/skbuff.h>
  13#include <linux/slab.h>
  14#include <linux/spinlock.h>
  15#include <net/dst.h>
  16#include <net/icmp.h>
  17#include <net/inet_ecn.h>
  18#include <net/xfrm.h>
  19
  20#if IS_ENABLED(CONFIG_IPV6)
  21#include <net/ip6_route.h>
  22#include <net/ipv6_stubs.h>
  23#endif
  24
  25#include "xfrm_inout.h"
  26
  27static int xfrm_output2(struct net *net, struct sock *sk, struct sk_buff *skb);
  28static int xfrm_inner_extract_output(struct xfrm_state *x, struct sk_buff *skb);
  29
  30static int xfrm_skb_check_space(struct sk_buff *skb)
  31{
  32        struct dst_entry *dst = skb_dst(skb);
  33        int nhead = dst->header_len + LL_RESERVED_SPACE(dst->dev)
  34                - skb_headroom(skb);
  35        int ntail = dst->dev->needed_tailroom - skb_tailroom(skb);
  36
  37        if (nhead <= 0) {
  38                if (ntail <= 0)
  39                        return 0;
  40                nhead = 0;
  41        } else if (ntail < 0)
  42                ntail = 0;
  43
  44        return pskb_expand_head(skb, nhead, ntail, GFP_ATOMIC);
  45}
  46
  47/* Children define the path of the packet through the
  48 * Linux networking.  Thus, destinations are stackable.
  49 */
  50
  51static struct dst_entry *skb_dst_pop(struct sk_buff *skb)
  52{
  53        struct dst_entry *child = dst_clone(xfrm_dst_child(skb_dst(skb)));
  54
  55        skb_dst_drop(skb);
  56        return child;
  57}
  58
  59/* Add encapsulation header.
  60 *
  61 * The IP header will be moved forward to make space for the encapsulation
  62 * header.
  63 */
  64static int xfrm4_transport_output(struct xfrm_state *x, struct sk_buff *skb)
  65{
  66        struct iphdr *iph = ip_hdr(skb);
  67        int ihl = iph->ihl * 4;
  68
  69        skb_set_inner_transport_header(skb, skb_transport_offset(skb));
  70
  71        skb_set_network_header(skb, -x->props.header_len);
  72        skb->mac_header = skb->network_header +
  73                          offsetof(struct iphdr, protocol);
  74        skb->transport_header = skb->network_header + ihl;
  75        __skb_pull(skb, ihl);
  76        memmove(skb_network_header(skb), iph, ihl);
  77        return 0;
  78}
  79
  80/* Add encapsulation header.
  81 *
  82 * The IP header and mutable extension headers will be moved forward to make
  83 * space for the encapsulation header.
  84 */
  85static int xfrm6_transport_output(struct xfrm_state *x, struct sk_buff *skb)
  86{
  87#if IS_ENABLED(CONFIG_IPV6)
  88        struct ipv6hdr *iph;
  89        u8 *prevhdr;
  90        int hdr_len;
  91
  92        iph = ipv6_hdr(skb);
  93        skb_set_inner_transport_header(skb, skb_transport_offset(skb));
  94
  95        hdr_len = x->type->hdr_offset(x, skb, &prevhdr);
  96        if (hdr_len < 0)
  97                return hdr_len;
  98        skb_set_mac_header(skb,
  99                           (prevhdr - x->props.header_len) - skb->data);
 100        skb_set_network_header(skb, -x->props.header_len);
 101        skb->transport_header = skb->network_header + hdr_len;
 102        __skb_pull(skb, hdr_len);
 103        memmove(ipv6_hdr(skb), iph, hdr_len);
 104        return 0;
 105#else
 106        WARN_ON_ONCE(1);
 107        return -EAFNOSUPPORT;
 108#endif
 109}
 110
 111/* Add route optimization header space.
 112 *
 113 * The IP header and mutable extension headers will be moved forward to make
 114 * space for the route optimization header.
 115 */
 116static int xfrm6_ro_output(struct xfrm_state *x, struct sk_buff *skb)
 117{
 118#if IS_ENABLED(CONFIG_IPV6)
 119        struct ipv6hdr *iph;
 120        u8 *prevhdr;
 121        int hdr_len;
 122
 123        iph = ipv6_hdr(skb);
 124
 125        hdr_len = x->type->hdr_offset(x, skb, &prevhdr);
 126        if (hdr_len < 0)
 127                return hdr_len;
 128        skb_set_mac_header(skb,
 129                           (prevhdr - x->props.header_len) - skb->data);
 130        skb_set_network_header(skb, -x->props.header_len);
 131        skb->transport_header = skb->network_header + hdr_len;
 132        __skb_pull(skb, hdr_len);
 133        memmove(ipv6_hdr(skb), iph, hdr_len);
 134
 135        x->lastused = ktime_get_real_seconds();
 136
 137        return 0;
 138#else
 139        WARN_ON_ONCE(1);
 140        return -EAFNOSUPPORT;
 141#endif
 142}
 143
 144/* Add encapsulation header.
 145 *
 146 * The top IP header will be constructed per draft-nikander-esp-beet-mode-06.txt.
 147 */
 148static int xfrm4_beet_encap_add(struct xfrm_state *x, struct sk_buff *skb)
 149{
 150        struct ip_beet_phdr *ph;
 151        struct iphdr *top_iph;
 152        int hdrlen, optlen;
 153
 154        hdrlen = 0;
 155        optlen = XFRM_MODE_SKB_CB(skb)->optlen;
 156        if (unlikely(optlen))
 157                hdrlen += IPV4_BEET_PHMAXLEN - (optlen & 4);
 158
 159        skb_set_network_header(skb, -x->props.header_len - hdrlen +
 160                               (XFRM_MODE_SKB_CB(skb)->ihl - sizeof(*top_iph)));
 161        if (x->sel.family != AF_INET6)
 162                skb->network_header += IPV4_BEET_PHMAXLEN;
 163        skb->mac_header = skb->network_header +
 164                          offsetof(struct iphdr, protocol);
 165        skb->transport_header = skb->network_header + sizeof(*top_iph);
 166
 167        xfrm4_beet_make_header(skb);
 168
 169        ph = __skb_pull(skb, XFRM_MODE_SKB_CB(skb)->ihl - hdrlen);
 170
 171        top_iph = ip_hdr(skb);
 172
 173        if (unlikely(optlen)) {
 174                if (WARN_ON(optlen < 0))
 175                        return -EINVAL;
 176
 177                ph->padlen = 4 - (optlen & 4);
 178                ph->hdrlen = optlen / 8;
 179                ph->nexthdr = top_iph->protocol;
 180                if (ph->padlen)
 181                        memset(ph + 1, IPOPT_NOP, ph->padlen);
 182
 183                top_iph->protocol = IPPROTO_BEETPH;
 184                top_iph->ihl = sizeof(struct iphdr) / 4;
 185        }
 186
 187        top_iph->saddr = x->props.saddr.a4;
 188        top_iph->daddr = x->id.daddr.a4;
 189
 190        return 0;
 191}
 192
 193/* Add encapsulation header.
 194 *
 195 * The top IP header will be constructed per RFC 2401.
 196 */
 197static int xfrm4_tunnel_encap_add(struct xfrm_state *x, struct sk_buff *skb)
 198{
 199        struct dst_entry *dst = skb_dst(skb);
 200        struct iphdr *top_iph;
 201        int flags;
 202
 203        skb_set_inner_network_header(skb, skb_network_offset(skb));
 204        skb_set_inner_transport_header(skb, skb_transport_offset(skb));
 205
 206        skb_set_network_header(skb, -x->props.header_len);
 207        skb->mac_header = skb->network_header +
 208                          offsetof(struct iphdr, protocol);
 209        skb->transport_header = skb->network_header + sizeof(*top_iph);
 210        top_iph = ip_hdr(skb);
 211
 212        top_iph->ihl = 5;
 213        top_iph->version = 4;
 214
 215        top_iph->protocol = xfrm_af2proto(skb_dst(skb)->ops->family);
 216
 217        /* DS disclosing depends on XFRM_SA_XFLAG_DONT_ENCAP_DSCP */
 218        if (x->props.extra_flags & XFRM_SA_XFLAG_DONT_ENCAP_DSCP)
 219                top_iph->tos = 0;
 220        else
 221                top_iph->tos = XFRM_MODE_SKB_CB(skb)->tos;
 222        top_iph->tos = INET_ECN_encapsulate(top_iph->tos,
 223                                            XFRM_MODE_SKB_CB(skb)->tos);
 224
 225        flags = x->props.flags;
 226        if (flags & XFRM_STATE_NOECN)
 227                IP_ECN_clear(top_iph);
 228
 229        top_iph->frag_off = (flags & XFRM_STATE_NOPMTUDISC) ?
 230                0 : (XFRM_MODE_SKB_CB(skb)->frag_off & htons(IP_DF));
 231
 232        top_iph->ttl = ip4_dst_hoplimit(xfrm_dst_child(dst));
 233
 234        top_iph->saddr = x->props.saddr.a4;
 235        top_iph->daddr = x->id.daddr.a4;
 236        ip_select_ident(dev_net(dst->dev), skb, NULL);
 237
 238        return 0;
 239}
 240
 241#if IS_ENABLED(CONFIG_IPV6)
 242static int xfrm6_tunnel_encap_add(struct xfrm_state *x, struct sk_buff *skb)
 243{
 244        struct dst_entry *dst = skb_dst(skb);
 245        struct ipv6hdr *top_iph;
 246        int dsfield;
 247
 248        skb_set_inner_network_header(skb, skb_network_offset(skb));
 249        skb_set_inner_transport_header(skb, skb_transport_offset(skb));
 250
 251        skb_set_network_header(skb, -x->props.header_len);
 252        skb->mac_header = skb->network_header +
 253                          offsetof(struct ipv6hdr, nexthdr);
 254        skb->transport_header = skb->network_header + sizeof(*top_iph);
 255        top_iph = ipv6_hdr(skb);
 256
 257        top_iph->version = 6;
 258
 259        memcpy(top_iph->flow_lbl, XFRM_MODE_SKB_CB(skb)->flow_lbl,
 260               sizeof(top_iph->flow_lbl));
 261        top_iph->nexthdr = xfrm_af2proto(skb_dst(skb)->ops->family);
 262
 263        if (x->props.extra_flags & XFRM_SA_XFLAG_DONT_ENCAP_DSCP)
 264                dsfield = 0;
 265        else
 266                dsfield = XFRM_MODE_SKB_CB(skb)->tos;
 267        dsfield = INET_ECN_encapsulate(dsfield, XFRM_MODE_SKB_CB(skb)->tos);
 268        if (x->props.flags & XFRM_STATE_NOECN)
 269                dsfield &= ~INET_ECN_MASK;
 270        ipv6_change_dsfield(top_iph, 0, dsfield);
 271        top_iph->hop_limit = ip6_dst_hoplimit(xfrm_dst_child(dst));
 272        top_iph->saddr = *(struct in6_addr *)&x->props.saddr;
 273        top_iph->daddr = *(struct in6_addr *)&x->id.daddr;
 274        return 0;
 275}
 276
 277static int xfrm6_beet_encap_add(struct xfrm_state *x, struct sk_buff *skb)
 278{
 279        struct ipv6hdr *top_iph;
 280        struct ip_beet_phdr *ph;
 281        int optlen, hdr_len;
 282
 283        hdr_len = 0;
 284        optlen = XFRM_MODE_SKB_CB(skb)->optlen;
 285        if (unlikely(optlen))
 286                hdr_len += IPV4_BEET_PHMAXLEN - (optlen & 4);
 287
 288        skb_set_network_header(skb, -x->props.header_len - hdr_len);
 289        if (x->sel.family != AF_INET6)
 290                skb->network_header += IPV4_BEET_PHMAXLEN;
 291        skb->mac_header = skb->network_header +
 292                          offsetof(struct ipv6hdr, nexthdr);
 293        skb->transport_header = skb->network_header + sizeof(*top_iph);
 294        ph = __skb_pull(skb, XFRM_MODE_SKB_CB(skb)->ihl - hdr_len);
 295
 296        xfrm6_beet_make_header(skb);
 297
 298        top_iph = ipv6_hdr(skb);
 299        if (unlikely(optlen)) {
 300                if (WARN_ON(optlen < 0))
 301                        return -EINVAL;
 302
 303                ph->padlen = 4 - (optlen & 4);
 304                ph->hdrlen = optlen / 8;
 305                ph->nexthdr = top_iph->nexthdr;
 306                if (ph->padlen)
 307                        memset(ph + 1, IPOPT_NOP, ph->padlen);
 308
 309                top_iph->nexthdr = IPPROTO_BEETPH;
 310        }
 311
 312        top_iph->saddr = *(struct in6_addr *)&x->props.saddr;
 313        top_iph->daddr = *(struct in6_addr *)&x->id.daddr;
 314        return 0;
 315}
 316#endif
 317
 318/* Add encapsulation header.
 319 *
 320 * On exit, the transport header will be set to the start of the
 321 * encapsulation header to be filled in by x->type->output and the mac
 322 * header will be set to the nextheader (protocol for IPv4) field of the
 323 * extension header directly preceding the encapsulation header, or in
 324 * its absence, that of the top IP header.
 325 * The value of the network header will always point to the top IP header
 326 * while skb->data will point to the payload.
 327 */
 328static int xfrm4_prepare_output(struct xfrm_state *x, struct sk_buff *skb)
 329{
 330        int err;
 331
 332        err = xfrm_inner_extract_output(x, skb);
 333        if (err)
 334                return err;
 335
 336        IPCB(skb)->flags |= IPSKB_XFRM_TUNNEL_SIZE;
 337        skb->protocol = htons(ETH_P_IP);
 338
 339        switch (x->outer_mode.encap) {
 340        case XFRM_MODE_BEET:
 341                return xfrm4_beet_encap_add(x, skb);
 342        case XFRM_MODE_TUNNEL:
 343                return xfrm4_tunnel_encap_add(x, skb);
 344        }
 345
 346        WARN_ON_ONCE(1);
 347        return -EOPNOTSUPP;
 348}
 349
 350static int xfrm6_prepare_output(struct xfrm_state *x, struct sk_buff *skb)
 351{
 352#if IS_ENABLED(CONFIG_IPV6)
 353        int err;
 354
 355        err = xfrm_inner_extract_output(x, skb);
 356        if (err)
 357                return err;
 358
 359        skb->ignore_df = 1;
 360        skb->protocol = htons(ETH_P_IPV6);
 361
 362        switch (x->outer_mode.encap) {
 363        case XFRM_MODE_BEET:
 364                return xfrm6_beet_encap_add(x, skb);
 365        case XFRM_MODE_TUNNEL:
 366                return xfrm6_tunnel_encap_add(x, skb);
 367        default:
 368                WARN_ON_ONCE(1);
 369                return -EOPNOTSUPP;
 370        }
 371#endif
 372        WARN_ON_ONCE(1);
 373        return -EAFNOSUPPORT;
 374}
 375
 376static int xfrm_outer_mode_output(struct xfrm_state *x, struct sk_buff *skb)
 377{
 378        switch (x->outer_mode.encap) {
 379        case XFRM_MODE_BEET:
 380        case XFRM_MODE_TUNNEL:
 381                if (x->outer_mode.family == AF_INET)
 382                        return xfrm4_prepare_output(x, skb);
 383                if (x->outer_mode.family == AF_INET6)
 384                        return xfrm6_prepare_output(x, skb);
 385                break;
 386        case XFRM_MODE_TRANSPORT:
 387                if (x->outer_mode.family == AF_INET)
 388                        return xfrm4_transport_output(x, skb);
 389                if (x->outer_mode.family == AF_INET6)
 390                        return xfrm6_transport_output(x, skb);
 391                break;
 392        case XFRM_MODE_ROUTEOPTIMIZATION:
 393                if (x->outer_mode.family == AF_INET6)
 394                        return xfrm6_ro_output(x, skb);
 395                WARN_ON_ONCE(1);
 396                break;
 397        default:
 398                WARN_ON_ONCE(1);
 399                break;
 400        }
 401
 402        return -EOPNOTSUPP;
 403}
 404
 405#if IS_ENABLED(CONFIG_NET_PKTGEN)
 406int pktgen_xfrm_outer_mode_output(struct xfrm_state *x, struct sk_buff *skb)
 407{
 408        return xfrm_outer_mode_output(x, skb);
 409}
 410EXPORT_SYMBOL_GPL(pktgen_xfrm_outer_mode_output);
 411#endif
 412
 413static int xfrm_output_one(struct sk_buff *skb, int err)
 414{
 415        struct dst_entry *dst = skb_dst(skb);
 416        struct xfrm_state *x = dst->xfrm;
 417        struct net *net = xs_net(x);
 418
 419        if (err <= 0)
 420                goto resume;
 421
 422        do {
 423                err = xfrm_skb_check_space(skb);
 424                if (err) {
 425                        XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
 426                        goto error_nolock;
 427                }
 428
 429                skb->mark = xfrm_smark_get(skb->mark, x);
 430
 431                err = xfrm_outer_mode_output(x, skb);
 432                if (err) {
 433                        XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEMODEERROR);
 434                        goto error_nolock;
 435                }
 436
 437                spin_lock_bh(&x->lock);
 438
 439                if (unlikely(x->km.state != XFRM_STATE_VALID)) {
 440                        XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEINVALID);
 441                        err = -EINVAL;
 442                        goto error;
 443                }
 444
 445                err = xfrm_state_check_expire(x);
 446                if (err) {
 447                        XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEEXPIRED);
 448                        goto error;
 449                }
 450
 451                err = x->repl->overflow(x, skb);
 452                if (err) {
 453                        XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATESEQERROR);
 454                        goto error;
 455                }
 456
 457                x->curlft.bytes += skb->len;
 458                x->curlft.packets++;
 459
 460                spin_unlock_bh(&x->lock);
 461
 462                skb_dst_force(skb);
 463                if (!skb_dst(skb)) {
 464                        XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
 465                        err = -EHOSTUNREACH;
 466                        goto error_nolock;
 467                }
 468
 469                if (xfrm_offload(skb)) {
 470                        x->type_offload->encap(x, skb);
 471                } else {
 472                        /* Inner headers are invalid now. */
 473                        skb->encapsulation = 0;
 474
 475                        err = x->type->output(x, skb);
 476                        if (err == -EINPROGRESS)
 477                                goto out;
 478                }
 479
 480resume:
 481                if (err) {
 482                        XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEPROTOERROR);
 483                        goto error_nolock;
 484                }
 485
 486                dst = skb_dst_pop(skb);
 487                if (!dst) {
 488                        XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
 489                        err = -EHOSTUNREACH;
 490                        goto error_nolock;
 491                }
 492                skb_dst_set(skb, dst);
 493                x = dst->xfrm;
 494        } while (x && !(x->outer_mode.flags & XFRM_MODE_FLAG_TUNNEL));
 495
 496        return 0;
 497
 498error:
 499        spin_unlock_bh(&x->lock);
 500error_nolock:
 501        kfree_skb(skb);
 502out:
 503        return err;
 504}
 505
 506int xfrm_output_resume(struct sk_buff *skb, int err)
 507{
 508        struct net *net = xs_net(skb_dst(skb)->xfrm);
 509
 510        while (likely((err = xfrm_output_one(skb, err)) == 0)) {
 511                nf_reset_ct(skb);
 512
 513                err = skb_dst(skb)->ops->local_out(net, skb->sk, skb);
 514                if (unlikely(err != 1))
 515                        goto out;
 516
 517                if (!skb_dst(skb)->xfrm)
 518                        return dst_output(net, skb->sk, skb);
 519
 520                err = nf_hook(skb_dst(skb)->ops->family,
 521                              NF_INET_POST_ROUTING, net, skb->sk, skb,
 522                              NULL, skb_dst(skb)->dev, xfrm_output2);
 523                if (unlikely(err != 1))
 524                        goto out;
 525        }
 526
 527        if (err == -EINPROGRESS)
 528                err = 0;
 529
 530out:
 531        return err;
 532}
 533EXPORT_SYMBOL_GPL(xfrm_output_resume);
 534
 535static int xfrm_output2(struct net *net, struct sock *sk, struct sk_buff *skb)
 536{
 537        return xfrm_output_resume(skb, 1);
 538}
 539
 540static int xfrm_output_gso(struct net *net, struct sock *sk, struct sk_buff *skb)
 541{
 542        struct sk_buff *segs, *nskb;
 543
 544        BUILD_BUG_ON(sizeof(*IPCB(skb)) > SKB_GSO_CB_OFFSET);
 545        BUILD_BUG_ON(sizeof(*IP6CB(skb)) > SKB_GSO_CB_OFFSET);
 546        segs = skb_gso_segment(skb, 0);
 547        kfree_skb(skb);
 548        if (IS_ERR(segs))
 549                return PTR_ERR(segs);
 550        if (segs == NULL)
 551                return -EINVAL;
 552
 553        skb_list_walk_safe(segs, segs, nskb) {
 554                int err;
 555
 556                skb_mark_not_on_list(segs);
 557                err = xfrm_output2(net, sk, segs);
 558
 559                if (unlikely(err)) {
 560                        kfree_skb_list(nskb);
 561                        return err;
 562                }
 563        }
 564
 565        return 0;
 566}
 567
 568int xfrm_output(struct sock *sk, struct sk_buff *skb)
 569{
 570        struct net *net = dev_net(skb_dst(skb)->dev);
 571        struct xfrm_state *x = skb_dst(skb)->xfrm;
 572        int err;
 573
 574        switch (x->outer_mode.family) {
 575        case AF_INET:
 576                memset(IPCB(skb), 0, sizeof(*IPCB(skb)));
 577                IPCB(skb)->flags |= IPSKB_XFRM_TRANSFORMED;
 578                break;
 579        case AF_INET6:
 580                memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));
 581
 582                IP6CB(skb)->flags |= IP6SKB_XFRM_TRANSFORMED;
 583                break;
 584        }
 585
 586        secpath_reset(skb);
 587
 588        if (xfrm_dev_offload_ok(skb, x)) {
 589                struct sec_path *sp;
 590
 591                sp = secpath_set(skb);
 592                if (!sp) {
 593                        XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
 594                        kfree_skb(skb);
 595                        return -ENOMEM;
 596                }
 597                skb->encapsulation = 1;
 598
 599                sp->olen++;
 600                sp->xvec[sp->len++] = x;
 601                xfrm_state_hold(x);
 602
 603                if (skb_is_gso(skb)) {
 604                        if (skb->inner_protocol)
 605                                return xfrm_output_gso(net, sk, skb);
 606
 607                        skb_shinfo(skb)->gso_type |= SKB_GSO_ESP;
 608                        goto out;
 609                }
 610
 611                if (x->xso.dev && x->xso.dev->features & NETIF_F_HW_ESP_TX_CSUM)
 612                        goto out;
 613        } else {
 614                if (skb_is_gso(skb))
 615                        return xfrm_output_gso(net, sk, skb);
 616        }
 617
 618        if (skb->ip_summed == CHECKSUM_PARTIAL) {
 619                err = skb_checksum_help(skb);
 620                if (err) {
 621                        XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
 622                        kfree_skb(skb);
 623                        return err;
 624                }
 625        }
 626
 627out:
 628        return xfrm_output2(net, sk, skb);
 629}
 630EXPORT_SYMBOL_GPL(xfrm_output);
 631
 632static int xfrm4_tunnel_check_size(struct sk_buff *skb)
 633{
 634        int mtu, ret = 0;
 635
 636        if (IPCB(skb)->flags & IPSKB_XFRM_TUNNEL_SIZE)
 637                goto out;
 638
 639        if (!(ip_hdr(skb)->frag_off & htons(IP_DF)) || skb->ignore_df)
 640                goto out;
 641
 642        mtu = dst_mtu(skb_dst(skb));
 643        if ((!skb_is_gso(skb) && skb->len > mtu) ||
 644            (skb_is_gso(skb) &&
 645             !skb_gso_validate_network_len(skb, ip_skb_dst_mtu(skb->sk, skb)))) {
 646                skb->protocol = htons(ETH_P_IP);
 647
 648                if (skb->sk)
 649                        xfrm_local_error(skb, mtu);
 650                else
 651                        icmp_send(skb, ICMP_DEST_UNREACH,
 652                                  ICMP_FRAG_NEEDED, htonl(mtu));
 653                ret = -EMSGSIZE;
 654        }
 655out:
 656        return ret;
 657}
 658
 659static int xfrm4_extract_output(struct xfrm_state *x, struct sk_buff *skb)
 660{
 661        int err;
 662
 663        err = xfrm4_tunnel_check_size(skb);
 664        if (err)
 665                return err;
 666
 667        XFRM_MODE_SKB_CB(skb)->protocol = ip_hdr(skb)->protocol;
 668
 669        xfrm4_extract_header(skb);
 670        return 0;
 671}
 672
 673#if IS_ENABLED(CONFIG_IPV6)
 674static int xfrm6_tunnel_check_size(struct sk_buff *skb)
 675{
 676        int mtu, ret = 0;
 677        struct dst_entry *dst = skb_dst(skb);
 678
 679        if (skb->ignore_df)
 680                goto out;
 681
 682        mtu = dst_mtu(dst);
 683        if (mtu < IPV6_MIN_MTU)
 684                mtu = IPV6_MIN_MTU;
 685
 686        if ((!skb_is_gso(skb) && skb->len > mtu) ||
 687            (skb_is_gso(skb) &&
 688             !skb_gso_validate_network_len(skb, ip6_skb_dst_mtu(skb)))) {
 689                skb->dev = dst->dev;
 690                skb->protocol = htons(ETH_P_IPV6);
 691
 692                if (xfrm6_local_dontfrag(skb->sk))
 693                        ipv6_stub->xfrm6_local_rxpmtu(skb, mtu);
 694                else if (skb->sk)
 695                        xfrm_local_error(skb, mtu);
 696                else
 697                        icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
 698                ret = -EMSGSIZE;
 699        }
 700out:
 701        return ret;
 702}
 703#endif
 704
 705static int xfrm6_extract_output(struct xfrm_state *x, struct sk_buff *skb)
 706{
 707#if IS_ENABLED(CONFIG_IPV6)
 708        int err;
 709
 710        err = xfrm6_tunnel_check_size(skb);
 711        if (err)
 712                return err;
 713
 714        XFRM_MODE_SKB_CB(skb)->protocol = ipv6_hdr(skb)->nexthdr;
 715
 716        xfrm6_extract_header(skb);
 717        return 0;
 718#else
 719        WARN_ON_ONCE(1);
 720        return -EAFNOSUPPORT;
 721#endif
 722}
 723
 724static int xfrm_inner_extract_output(struct xfrm_state *x, struct sk_buff *skb)
 725{
 726        const struct xfrm_mode *inner_mode;
 727
 728        if (x->sel.family == AF_UNSPEC)
 729                inner_mode = xfrm_ip2inner_mode(x,
 730                                xfrm_af2proto(skb_dst(skb)->ops->family));
 731        else
 732                inner_mode = &x->inner_mode;
 733
 734        if (inner_mode == NULL)
 735                return -EAFNOSUPPORT;
 736
 737        switch (inner_mode->family) {
 738        case AF_INET:
 739                return xfrm4_extract_output(x, skb);
 740        case AF_INET6:
 741                return xfrm6_extract_output(x, skb);
 742        }
 743
 744        return -EAFNOSUPPORT;
 745}
 746
 747void xfrm_local_error(struct sk_buff *skb, int mtu)
 748{
 749        unsigned int proto;
 750        struct xfrm_state_afinfo *afinfo;
 751
 752        if (skb->protocol == htons(ETH_P_IP))
 753                proto = AF_INET;
 754        else if (skb->protocol == htons(ETH_P_IPV6) &&
 755                 skb->sk->sk_family == AF_INET6)
 756                proto = AF_INET6;
 757        else
 758                return;
 759
 760        afinfo = xfrm_state_get_afinfo(proto);
 761        if (afinfo) {
 762                afinfo->local_error(skb, mtu);
 763                rcu_read_unlock();
 764        }
 765}
 766EXPORT_SYMBOL_GPL(xfrm_local_error);
 767