net/ipv6/xfrm6_output.c

   1 /*
   2  * xfrm6_output.c - Common IPsec encapsulation code for IPv6.
   3  * Copyright (C) 2002 USAGI/WIDE Project
   4  * Copyright (c) 2004 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/if_ether.h>
  13 #include <linux/compiler.h>
  14 #include <linux/skbuff.h>
  15 #include <linux/icmpv6.h>
  16 #include <linux/netfilter_ipv6.h>
  17 #include <net/ipv6.h>
  18 #include <net/xfrm.h>
  19
  20 int xfrm6_find_1stfragopt(struct xfrm_state *x, struct sk_buff *skb,
  21                           u8 **prevhdr)
  22 {
  23         return ip6_find_1stfragopt(skb, prevhdr);
  24 }
  25
  26 EXPORT_SYMBOL(xfrm6_find_1stfragopt);
  27
  28 static int xfrm6_tunnel_check_size(struct sk_buff *skb)
  29 {
  30         int mtu, ret = 0;
  31         struct dst_entry *dst = skb->dst;
  32
  33         mtu = dst_mtu(dst);
  34         if (mtu < IPV6_MIN_MTU)
  35                 mtu = IPV6_MIN_MTU;
  36
  37         if (skb->len > mtu) {
  38                 skb->dev = dst->dev;
  39                 icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu, skb->dev);
  40                 ret = -EMSGSIZE;
  41         }
  42
  43         return ret;
  44 }
  45
  46 static inline int xfrm6_output_one(struct sk_buff *skb)
  47 {
  48         struct dst_entry *dst = skb->dst;
  49         struct xfrm_state *x = dst->xfrm;
  50         struct ipv6hdr *iph;
  51         int err;
  52
  53         if (x->props.mode == XFRM_MODE_TUNNEL) {
  54                 err = xfrm6_tunnel_check_size(skb);
  55                 if (err)
  56                         goto error_nolock;
  57         }
  58
  59         err = xfrm_output(skb);
  60         if (err)
  61                 goto error_nolock;
  62
  63         iph = ipv6_hdr(skb);
  64         iph->payload_len = htons(skb->len - sizeof(*iph));
  65
  66         IP6CB(skb)->flags |= IP6SKB_XFRM_TRANSFORMED;
  67         err = 0;
  68
  69 out_exit:
  70         return err;
  71 error_nolock:
  72         kfree_skb(skb);
  73         goto out_exit;
  74 }
  75
  76 static int xfrm6_output_finish2(struct sk_buff *skb)
  77 {
  78         int err;
  79
  80         while (likely((err = xfrm6_output_one(skb)) == 0)) {
  81                 nf_reset(skb);
  82
  83                 err = nf_hook(PF_INET6, NF_IP6_LOCAL_OUT, skb, NULL,
  84                               skb->dst->dev, dst_output);
  85                 if (unlikely(err != 1))
  86                         break;
  87
  88                 if (!skb->dst->xfrm)
  89                         return dst_output(skb);
  90
  91                 err = nf_hook(PF_INET6, NF_IP6_POST_ROUTING, skb, NULL,
  92                               skb->dst->dev, xfrm6_output_finish2);
  93                 if (unlikely(err != 1))
  94                         break;
  95         }
  96
  97         return err;
  98 }
  99
 100 static int xfrm6_output_finish(struct sk_buff *skb)
 101 {
 102         struct sk_buff *segs;
 103
 104         if (!skb_is_gso(skb))
 105                 return xfrm6_output_finish2(skb);
 106
 107         skb->protocol = htons(ETH_P_IPV6);
 108         segs = skb_gso_segment(skb, 0);
 109         kfree_skb(skb);
 110         if (unlikely(IS_ERR(segs)))
 111                 return PTR_ERR(segs);
 112
 113         do {
 114                 struct sk_buff *nskb = segs->next;
 115                 int err;
 116
 117                 segs->next = NULL;
 118                 err = xfrm6_output_finish2(segs);
 119
 120                 if (unlikely(err)) {
 121                         while ((segs = nskb)) {
 122                                 nskb = segs->next;
 123                                 segs->next = NULL;
 124                                 kfree_skb(segs);
 125                         }
 126                         return err;
 127                 }
 128
 129                 segs = nskb;
 130         } while (segs);
 131
 132         return 0;
 133 }
 134
 135 int xfrm6_output(struct sk_buff *skb)
 136 {
 137         return NF_HOOK(PF_INET6, NF_IP6_POST_ROUTING, skb, NULL, skb->dst->dev,
 138                        xfrm6_output_finish);
 139 }