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 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
  41static int xfrm_output_one(struct sk_buff *skb, int err)
  42{
  43        struct dst_entry *dst = skb_dst(skb);
  44        struct xfrm_state *x = dst->xfrm;
  45        struct net *net = xs_net(x);
  46
  47        if (err <= 0)
  48                goto resume;
  49
  50        do {
  51                err = xfrm_skb_check_space(skb);
  52                if (err) {
  53                        XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
  54                        goto error_nolock;
  55                }
  56
  57                err = x->outer_mode->output(x, skb);
  58                if (err) {
  59                        XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEMODEERROR);
  60                        goto error_nolock;
  61                }
  62
  63                spin_lock_bh(&x->lock);
  64
  65                if (unlikely(x->km.state != XFRM_STATE_VALID)) {
  66                        XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEINVALID);
  67                        err = -EINVAL;
  68                        goto error;
  69                }
  70
  71                err = xfrm_state_check_expire(x);
  72                if (err) {
  73                        XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEEXPIRED);
  74                        goto error;
  75                }
  76
  77                err = x->repl->overflow(x, skb);
  78                if (err) {
  79                        XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATESEQERROR);
  80                        goto error;
  81                }
  82
  83                x->curlft.bytes += skb->len;
  84                x->curlft.packets++;
  85
  86                spin_unlock_bh(&x->lock);
  87
  88                skb_dst_force(skb);
  89
  90                err = x->type->output(x, skb);
  91                if (err == -EINPROGRESS)
  92                        goto out;
  93
  94resume:
  95                if (err) {
  96                        XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEPROTOERROR);
  97                        goto error_nolock;
  98                }
  99
 100                dst = skb_dst_pop(skb);
 101                if (!dst) {
 102                        XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
 103                        err = -EHOSTUNREACH;
 104                        goto error_nolock;
 105                }
 106                skb_dst_set(skb, dst);
 107                x = dst->xfrm;
 108        } while (x && !(x->outer_mode->flags & XFRM_MODE_FLAG_TUNNEL));
 109
 110        return 0;
 111
 112error:
 113        spin_unlock_bh(&x->lock);
 114error_nolock:
 115        kfree_skb(skb);
 116out:
 117        return err;
 118}
 119
 120int xfrm_output_resume(struct sk_buff *skb, int err)
 121{
 122        while (likely((err = xfrm_output_one(skb, err)) == 0)) {
 123                nf_reset(skb);
 124
 125                err = skb_dst(skb)->ops->local_out(skb);
 126                if (unlikely(err != 1))
 127                        goto out;
 128
 129                if (!skb_dst(skb)->xfrm)
 130                        return dst_output(skb);
 131
 132                err = nf_hook(skb_dst(skb)->ops->family,
 133                              NF_INET_POST_ROUTING, skb,
 134                              NULL, skb_dst(skb)->dev, xfrm_output2);
 135                if (unlikely(err != 1))
 136                        goto out;
 137        }
 138
 139        if (err == -EINPROGRESS)
 140                err = 0;
 141
 142out:
 143        return err;
 144}
 145EXPORT_SYMBOL_GPL(xfrm_output_resume);
 146
 147static int xfrm_output2(struct sk_buff *skb)
 148{
 149        return xfrm_output_resume(skb, 1);
 150}
 151
 152static int xfrm_output_gso(struct sk_buff *skb)
 153{
 154        struct sk_buff *segs;
 155
 156        segs = skb_gso_segment(skb, 0);
 157        kfree_skb(skb);
 158        if (IS_ERR(segs))
 159                return PTR_ERR(segs);
 160
 161        do {
 162                struct sk_buff *nskb = segs->next;
 163                int err;
 164
 165                segs->next = NULL;
 166                err = xfrm_output2(segs);
 167
 168                if (unlikely(err)) {
 169                        while ((segs = nskb)) {
 170                                nskb = segs->next;
 171                                segs->next = NULL;
 172                                kfree_skb(segs);
 173                        }
 174                        return err;
 175                }
 176
 177                segs = nskb;
 178        } while (segs);
 179
 180        return 0;
 181}
 182
 183int xfrm_output(struct sk_buff *skb)
 184{
 185        struct net *net = dev_net(skb_dst(skb)->dev);
 186        int err;
 187
 188        if (skb_is_gso(skb))
 189                return xfrm_output_gso(skb);
 190
 191        if (skb->ip_summed == CHECKSUM_PARTIAL) {
 192                err = skb_checksum_help(skb);
 193                if (err) {
 194                        XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
 195                        kfree_skb(skb);
 196                        return err;
 197                }
 198        }
 199
 200        return xfrm_output2(skb);
 201}
 202
 203int xfrm_inner_extract_output(struct xfrm_state *x, struct sk_buff *skb)
 204{
 205        struct xfrm_mode *inner_mode;
 206        if (x->sel.family == AF_UNSPEC)
 207                inner_mode = xfrm_ip2inner_mode(x,
 208                                xfrm_af2proto(skb_dst(skb)->ops->family));
 209        else
 210                inner_mode = x->inner_mode;
 211
 212        if (inner_mode == NULL)
 213                return -EAFNOSUPPORT;
 214        return inner_mode->afinfo->extract_output(x, skb);
 215}
 216
 217void xfrm_local_error(struct sk_buff *skb, int mtu)
 218{
 219        unsigned int proto;
 220        struct xfrm_state_afinfo *afinfo;
 221
 222        if (skb->protocol == htons(ETH_P_IP))
 223                proto = AF_INET;
 224        else if (skb->protocol == htons(ETH_P_IPV6))
 225                proto = AF_INET6;
 226        else
 227                return;
 228
 229        afinfo = xfrm_state_get_afinfo(proto);
 230        if (!afinfo)
 231                return;
 232
 233        afinfo->local_error(skb, mtu);
 234        xfrm_state_put_afinfo(afinfo);
 235}
 236
 237EXPORT_SYMBOL_GPL(xfrm_output);
 238EXPORT_SYMBOL_GPL(xfrm_inner_extract_output);
 239EXPORT_SYMBOL_GPL(xfrm_local_error);
 240