linux/net/xfrm/xfrm_output.c
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   1/*
   2 * xfrm_output.c - Common IPsec encapsulation code.
   3 *
   4 * Copyright (c) 2007 Herbert Xu <herbert@gondor.apana.org.au>
   5 *
   6 * This program is free software; you can redistribute it and/or
   7 * modify it under the terms of the GNU General Public License
   8 * as published by the Free Software Foundation; either version
   9 * 2 of the License, or (at your option) any later version.
  10 */
  11
  12#include <linux/errno.h>
  13#include <linux/module.h>
  14#include <linux/netdevice.h>
  15#include <linux/netfilter.h>
  16#include <linux/skbuff.h>
  17#include <linux/slab.h>
  18#include <linux/spinlock.h>
  19#include <net/dst.h>
  20#include <net/xfrm.h>
  21
  22static int xfrm_output2(struct net *net, struct sock *sk, struct sk_buff *skb);
  23
  24static 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
  45static struct dst_entry *skb_dst_pop(struct sk_buff *skb)
  46{
  47        struct dst_entry *child = dst_clone(skb_dst(skb)->child);
  48
  49        skb_dst_drop(skb);
  50        return child;
  51}
  52
  53static int xfrm_output_one(struct sk_buff *skb, int err)
  54{
  55        struct dst_entry *dst = skb_dst(skb);
  56        struct xfrm_state *x = dst->xfrm;
  57        struct net *net = xs_net(x);
  58
  59        if (err <= 0)
  60                goto resume;
  61
  62        do {
  63                err = xfrm_skb_check_space(skb);
  64                if (err) {
  65                        XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
  66                        goto error_nolock;
  67                }
  68
  69                if (x->props.output_mark)
  70                        skb->mark = x->props.output_mark;
  71
  72                err = x->outer_mode->output(x, skb);
  73                if (err) {
  74                        XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEMODEERROR);
  75                        goto error_nolock;
  76                }
  77
  78                spin_lock_bh(&x->lock);
  79
  80                if (unlikely(x->km.state != XFRM_STATE_VALID)) {
  81                        XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEINVALID);
  82                        err = -EINVAL;
  83                        goto error;
  84                }
  85
  86                err = xfrm_state_check_expire(x);
  87                if (err) {
  88                        XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEEXPIRED);
  89                        goto error;
  90                }
  91
  92                err = x->repl->overflow(x, skb);
  93                if (err) {
  94                        XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATESEQERROR);
  95                        goto error;
  96                }
  97
  98                x->curlft.bytes += skb->len;
  99                x->curlft.packets++;
 100
 101                spin_unlock_bh(&x->lock);
 102
 103                skb_dst_force(skb);
 104
 105                if (xfrm_offload(skb)) {
 106                        x->type_offload->encap(x, skb);
 107                } else {
 108                        /* Inner headers are invalid now. */
 109                        skb->encapsulation = 0;
 110
 111                        err = x->type->output(x, skb);
 112                        if (err == -EINPROGRESS)
 113                                goto out;
 114                }
 115
 116resume:
 117                if (err) {
 118                        XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEPROTOERROR);
 119                        goto error_nolock;
 120                }
 121
 122                dst = skb_dst_pop(skb);
 123                if (!dst) {
 124                        XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
 125                        err = -EHOSTUNREACH;
 126                        goto error_nolock;
 127                }
 128                skb_dst_set(skb, dst);
 129                x = dst->xfrm;
 130        } while (x && !(x->outer_mode->flags & XFRM_MODE_FLAG_TUNNEL));
 131
 132        return 0;
 133
 134error:
 135        spin_unlock_bh(&x->lock);
 136error_nolock:
 137        kfree_skb(skb);
 138out:
 139        return err;
 140}
 141
 142int xfrm_output_resume(struct sk_buff *skb, int err)
 143{
 144        struct net *net = xs_net(skb_dst(skb)->xfrm);
 145
 146        while (likely((err = xfrm_output_one(skb, err)) == 0)) {
 147                nf_reset(skb);
 148
 149                err = skb_dst(skb)->ops->local_out(net, skb->sk, skb);
 150                if (unlikely(err != 1))
 151                        goto out;
 152
 153                if (!skb_dst(skb)->xfrm)
 154                        return dst_output(net, skb->sk, skb);
 155
 156                err = nf_hook(skb_dst(skb)->ops->family,
 157                              NF_INET_POST_ROUTING, net, skb->sk, skb,
 158                              NULL, skb_dst(skb)->dev, xfrm_output2);
 159                if (unlikely(err != 1))
 160                        goto out;
 161        }
 162
 163        if (err == -EINPROGRESS)
 164                err = 0;
 165
 166out:
 167        return err;
 168}
 169EXPORT_SYMBOL_GPL(xfrm_output_resume);
 170
 171static int xfrm_output2(struct net *net, struct sock *sk, struct sk_buff *skb)
 172{
 173        return xfrm_output_resume(skb, 1);
 174}
 175
 176static int xfrm_output_gso(struct net *net, struct sock *sk, struct sk_buff *skb)
 177{
 178        struct sk_buff *segs;
 179
 180        BUILD_BUG_ON(sizeof(*IPCB(skb)) > SKB_SGO_CB_OFFSET);
 181        BUILD_BUG_ON(sizeof(*IP6CB(skb)) > SKB_SGO_CB_OFFSET);
 182        segs = skb_gso_segment(skb, 0);
 183        kfree_skb(skb);
 184        if (IS_ERR(segs))
 185                return PTR_ERR(segs);
 186        if (segs == NULL)
 187                return -EINVAL;
 188
 189        do {
 190                struct sk_buff *nskb = segs->next;
 191                int err;
 192
 193                segs->next = NULL;
 194                err = xfrm_output2(net, sk, segs);
 195
 196                if (unlikely(err)) {
 197                        kfree_skb_list(nskb);
 198                        return err;
 199                }
 200
 201                segs = nskb;
 202        } while (segs);
 203
 204        return 0;
 205}
 206
 207int xfrm_output(struct sock *sk, struct sk_buff *skb)
 208{
 209        struct net *net = dev_net(skb_dst(skb)->dev);
 210        struct xfrm_state *x = skb_dst(skb)->xfrm;
 211        int err;
 212
 213        secpath_reset(skb);
 214
 215        if (xfrm_dev_offload_ok(skb, x)) {
 216                struct sec_path *sp;
 217
 218                sp = secpath_dup(skb->sp);
 219                if (!sp) {
 220                        XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
 221                        kfree_skb(skb);
 222                        return -ENOMEM;
 223                }
 224                if (skb->sp)
 225                        secpath_put(skb->sp);
 226                skb->sp = sp;
 227                skb->encapsulation = 1;
 228
 229                sp->olen++;
 230                sp->xvec[skb->sp->len++] = x;
 231                xfrm_state_hold(x);
 232
 233                if (skb_is_gso(skb)) {
 234                        skb_shinfo(skb)->gso_type |= SKB_GSO_ESP;
 235
 236                        return xfrm_output2(net, sk, skb);
 237                }
 238
 239                if (x->xso.dev && x->xso.dev->features & NETIF_F_HW_ESP_TX_CSUM)
 240                        goto out;
 241        }
 242
 243        if (skb_is_gso(skb))
 244                return xfrm_output_gso(net, sk, skb);
 245
 246        if (skb->ip_summed == CHECKSUM_PARTIAL) {
 247                err = skb_checksum_help(skb);
 248                if (err) {
 249                        XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
 250                        kfree_skb(skb);
 251                        return err;
 252                }
 253        }
 254
 255out:
 256        return xfrm_output2(net, sk, skb);
 257}
 258EXPORT_SYMBOL_GPL(xfrm_output);
 259
 260int xfrm_inner_extract_output(struct xfrm_state *x, struct sk_buff *skb)
 261{
 262        struct xfrm_mode *inner_mode;
 263        if (x->sel.family == AF_UNSPEC)
 264                inner_mode = xfrm_ip2inner_mode(x,
 265                                xfrm_af2proto(skb_dst(skb)->ops->family));
 266        else
 267                inner_mode = x->inner_mode;
 268
 269        if (inner_mode == NULL)
 270                return -EAFNOSUPPORT;
 271        return inner_mode->afinfo->extract_output(x, skb);
 272}
 273EXPORT_SYMBOL_GPL(xfrm_inner_extract_output);
 274
 275void xfrm_local_error(struct sk_buff *skb, int mtu)
 276{
 277        unsigned int proto;
 278        struct xfrm_state_afinfo *afinfo;
 279
 280        if (skb->protocol == htons(ETH_P_IP))
 281                proto = AF_INET;
 282        else if (skb->protocol == htons(ETH_P_IPV6))
 283                proto = AF_INET6;
 284        else
 285                return;
 286
 287        afinfo = xfrm_state_get_afinfo(proto);
 288        if (afinfo)
 289                afinfo->local_error(skb, mtu);
 290        rcu_read_unlock();
 291}
 292EXPORT_SYMBOL_GPL(xfrm_local_error);
 293