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                err = xfrm_state_check_expire(x);
  65                if (err) {
  66                        XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEEXPIRED);
  67                        goto error;
  68                }
  69
  70                err = x->repl->overflow(x, skb);
  71                if (err) {
  72                        XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATESEQERROR);
  73                        goto error;
  74                }
  75
  76                x->curlft.bytes += skb->len;
  77                x->curlft.packets++;
  78
  79                spin_unlock_bh(&x->lock);
  80
  81                skb_dst_force(skb);
  82
  83                err = x->type->output(x, skb);
  84                if (err == -EINPROGRESS)
  85                        goto out_exit;
  86
  87resume:
  88                if (err) {
  89                        XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEPROTOERROR);
  90                        goto error_nolock;
  91                }
  92
  93                dst = skb_dst_pop(skb);
  94                if (!dst) {
  95                        XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
  96                        err = -EHOSTUNREACH;
  97                        goto error_nolock;
  98                }
  99                skb_dst_set(skb, dst);
 100                x = dst->xfrm;
 101        } while (x && !(x->outer_mode->flags & XFRM_MODE_FLAG_TUNNEL));
 102
 103        err = 0;
 104
 105out_exit:
 106        return err;
 107error:
 108        spin_unlock_bh(&x->lock);
 109error_nolock:
 110        kfree_skb(skb);
 111        goto out_exit;
 112}
 113
 114int xfrm_output_resume(struct sk_buff *skb, int err)
 115{
 116        while (likely((err = xfrm_output_one(skb, err)) == 0)) {
 117                nf_reset(skb);
 118
 119                err = skb_dst(skb)->ops->local_out(skb);
 120                if (unlikely(err != 1))
 121                        goto out;
 122
 123                if (!skb_dst(skb)->xfrm)
 124                        return dst_output(skb);
 125
 126                err = nf_hook(skb_dst(skb)->ops->family,
 127                              NF_INET_POST_ROUTING, skb,
 128                              NULL, skb_dst(skb)->dev, xfrm_output2);
 129                if (unlikely(err != 1))
 130                        goto out;
 131        }
 132
 133        if (err == -EINPROGRESS)
 134                err = 0;
 135
 136out:
 137        return err;
 138}
 139EXPORT_SYMBOL_GPL(xfrm_output_resume);
 140
 141static int xfrm_output2(struct sk_buff *skb)
 142{
 143        return xfrm_output_resume(skb, 1);
 144}
 145
 146static int xfrm_output_gso(struct sk_buff *skb)
 147{
 148        struct sk_buff *segs;
 149
 150        segs = skb_gso_segment(skb, 0);
 151        kfree_skb(skb);
 152        if (IS_ERR(segs))
 153                return PTR_ERR(segs);
 154
 155        do {
 156                struct sk_buff *nskb = segs->next;
 157                int err;
 158
 159                segs->next = NULL;
 160                err = xfrm_output2(segs);
 161
 162                if (unlikely(err)) {
 163                        while ((segs = nskb)) {
 164                                nskb = segs->next;
 165                                segs->next = NULL;
 166                                kfree_skb(segs);
 167                        }
 168                        return err;
 169                }
 170
 171                segs = nskb;
 172        } while (segs);
 173
 174        return 0;
 175}
 176
 177int xfrm_output(struct sk_buff *skb)
 178{
 179        struct net *net = dev_net(skb_dst(skb)->dev);
 180        int err;
 181
 182        if (skb_is_gso(skb))
 183                return xfrm_output_gso(skb);
 184
 185        if (skb->ip_summed == CHECKSUM_PARTIAL) {
 186                err = skb_checksum_help(skb);
 187                if (err) {
 188                        XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
 189                        kfree_skb(skb);
 190                        return err;
 191                }
 192        }
 193
 194        return xfrm_output2(skb);
 195}
 196
 197int xfrm_inner_extract_output(struct xfrm_state *x, struct sk_buff *skb)
 198{
 199        struct xfrm_mode *inner_mode;
 200        if (x->sel.family == AF_UNSPEC)
 201                inner_mode = xfrm_ip2inner_mode(x,
 202                                xfrm_af2proto(skb_dst(skb)->ops->family));
 203        else
 204                inner_mode = x->inner_mode;
 205
 206        if (inner_mode == NULL)
 207                return -EAFNOSUPPORT;
 208        return inner_mode->afinfo->extract_output(x, skb);
 209}
 210
 211EXPORT_SYMBOL_GPL(xfrm_output);
 212EXPORT_SYMBOL_GPL(xfrm_inner_extract_output);
 213
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