net/xfrm/xfrm_output.c

   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
  22 static int xfrm_output2(struct net *net, struct sock *sk, 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(skb_dst(skb)->child);
  48
  49         skb_dst_drop(skb);
  50         return child;
  51 }
  52
  53 static 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                 err = x->outer_mode->output(x, skb);
  70                 if (err) {
  71                         XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEMODEERROR);
  72                         goto error_nolock;
  73                 }
  74
  75                 spin_lock_bh(&x->lock);
  76
  77                 if (unlikely(x->km.state != XFRM_STATE_VALID)) {
  78                         XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEINVALID);
  79                         err = -EINVAL;
  80                         goto error;
  81                 }
  82
  83                 err = xfrm_state_check_expire(x);
  84                 if (err) {
  85                         XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEEXPIRED);
  86                         goto error;
  87                 }
  88
  89                 err = x->repl->overflow(x, skb);
  90                 if (err) {
  91                         XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATESEQERROR);
  92                         goto error;
  93                 }
  94
  95                 x->curlft.bytes += skb->len;
  96                 x->curlft.packets++;
  97
  98                 spin_unlock_bh(&x->lock);
  99
 100                 skb_dst_force(skb);
 101
 102                 /* Inner headers are invalid now. */
 103                 skb->encapsulation = 0;
 104
 105                 err = x->type->output(x, skb);
 106                 if (err == -EINPROGRESS)
 107                         goto out;
 108
 109 resume:
 110                 if (err) {
 111                         XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEPROTOERROR);
 112                         goto error_nolock;
 113                 }
 114
 115                 dst = skb_dst_pop(skb);
 116                 if (!dst) {
 117                         XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
 118                         err = -EHOSTUNREACH;
 119                         goto error_nolock;
 120                 }
 121                 skb_dst_set(skb, dst);
 122                 x = dst->xfrm;
 123         } while (x && !(x->outer_mode->flags & XFRM_MODE_FLAG_TUNNEL));
 124
 125         return 0;
 126
 127 error:
 128         spin_unlock_bh(&x->lock);
 129 error_nolock:
 130         kfree_skb(skb);
 131 out:
 132         return err;
 133 }
 134
 135 int xfrm_output_resume(struct sk_buff *skb, int err)
 136 {
 137         struct net *net = xs_net(skb_dst(skb)->xfrm);
 138
 139         while (likely((err = xfrm_output_one(skb, err)) == 0)) {
 140                 nf_reset(skb);
 141
 142                 err = skb_dst(skb)->ops->local_out(net, skb->sk, skb);
 143                 if (unlikely(err != 1))
 144                         goto out;
 145
 146                 if (!skb_dst(skb)->xfrm)
 147                         return dst_output(net, skb->sk, skb);
 148
 149                 err = nf_hook(skb_dst(skb)->ops->family,
 150                               NF_INET_POST_ROUTING, net, skb->sk, skb,
 151                               NULL, skb_dst(skb)->dev, xfrm_output2);
 152                 if (unlikely(err != 1))
 153                         goto out;
 154         }
 155
 156         if (err == -EINPROGRESS)
 157                 err = 0;
 158
 159 out:
 160         return err;
 161 }
 162 EXPORT_SYMBOL_GPL(xfrm_output_resume);
 163
 164 static int xfrm_output2(struct net *net, struct sock *sk, struct sk_buff *skb)
 165 {
 166         return xfrm_output_resume(skb, 1);
 167 }
 168
 169 static int xfrm_output_gso(struct net *net, struct sock *sk, struct sk_buff *skb)
 170 {
 171         struct sk_buff *segs;
 172
 173         BUILD_BUG_ON(sizeof(*IPCB(skb)) > SKB_SGO_CB_OFFSET);
 174         BUILD_BUG_ON(sizeof(*IP6CB(skb)) > SKB_SGO_CB_OFFSET);
 175         segs = skb_gso_segment(skb, 0);
 176         kfree_skb(skb);
 177         if (IS_ERR(segs))
 178                 return PTR_ERR(segs);
 179         if (segs == NULL)
 180                 return -EINVAL;
 181
 182         do {
 183                 struct sk_buff *nskb = segs->next;
 184                 int err;
 185
 186                 segs->next = NULL;
 187                 err = xfrm_output2(net, sk, segs);
 188
 189                 if (unlikely(err)) {
 190                         kfree_skb_list(nskb);
 191                         return err;
 192                 }
 193
 194                 segs = nskb;
 195         } while (segs);
 196
 197         return 0;
 198 }
 199
 200 int xfrm_output(struct sock *sk, struct sk_buff *skb)
 201 {
 202         struct net *net = dev_net(skb_dst(skb)->dev);
 203         int err;
 204
 205         if (skb_is_gso(skb))
 206                 return xfrm_output_gso(net, sk, skb);
 207
 208         if (skb->ip_summed == CHECKSUM_PARTIAL) {
 209                 err = skb_checksum_help(skb);
 210                 if (err) {
 211                         XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
 212                         kfree_skb(skb);
 213                         return err;
 214                 }
 215         }
 216
 217         return xfrm_output2(net, sk, skb);
 218 }
 219 EXPORT_SYMBOL_GPL(xfrm_output);
 220
 221 int xfrm_inner_extract_output(struct xfrm_state *x, struct sk_buff *skb)
 222 {
 223         struct xfrm_mode *inner_mode;
 224         if (x->sel.family == AF_UNSPEC)
 225                 inner_mode = xfrm_ip2inner_mode(x,
 226                                 xfrm_af2proto(skb_dst(skb)->ops->family));
 227         else
 228                 inner_mode = x->inner_mode;
 229
 230         if (inner_mode == NULL)
 231                 return -EAFNOSUPPORT;
 232         return inner_mode->afinfo->extract_output(x, skb);
 233 }
 234 EXPORT_SYMBOL_GPL(xfrm_inner_extract_output);
 235
 236 void xfrm_local_error(struct sk_buff *skb, int mtu)
 237 {
 238         unsigned int proto;
 239         struct xfrm_state_afinfo *afinfo;
 240
 241         if (skb->protocol == htons(ETH_P_IP))
 242                 proto = AF_INET;
 243         else if (skb->protocol == htons(ETH_P_IPV6))
 244                 proto = AF_INET6;
 245         else
 246                 return;
 247
 248         afinfo = xfrm_state_get_afinfo(proto);
 249         if (!afinfo)
 250                 return;
 251
 252         afinfo->local_error(skb, mtu);
 253         xfrm_state_put_afinfo(afinfo);
 254 }
 255 EXPORT_SYMBOL_GPL(xfrm_local_error);