net/xfrm/xfrm_output.c

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