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/compiler.h> 13 #include <linux/skbuff.h> 14 #include <linux/spinlock.h> 15 #include <linux/icmpv6.h> 16 #include <linux/netfilter_ipv6.h> 17 #include <net/dsfield.h> 18 #include <net/inet_ecn.h> 19 #include <net/ipv6.h> 20 #include <net/xfrm.h> 21 22 /* Add encapsulation header. 23 * 24 * In transport mode, the IP header and mutable extension headers will be moved 25 * forward to make space for the encapsulation header. 26 * 27 * In tunnel mode, the top IP header will be constructed per RFC 2401. 28 * The following fields in it shall be filled in by x->type->output: 29 * payload_len 30 * 31 * On exit, skb->h will be set to the start of the encapsulation header to be 32 * filled in by x->type->output and skb->nh will be set to the nextheader field 33 * of the extension header directly preceding the encapsulation header, or in 34 * its absence, that of the top IP header. The value of skb->data will always 35 * point to the top IP header. 36 */ 37 static void xfrm6_encap(struct sk_buff *skb) 38 { 39 struct dst_entry *dst = skb->dst; 40 struct xfrm_state *x = dst->xfrm; 41 struct ipv6hdr *iph, *top_iph; 42 int dsfield; 43 44 skb_push(skb, x->props.header_len); 45 iph = skb->nh.ipv6h; 46 47 if (!x->props.mode) { 48 u8 *prevhdr; 49 int hdr_len; 50 51 hdr_len = ip6_find_1stfragopt(skb, &prevhdr); 52 skb->nh.raw = prevhdr - x->props.header_len; 53 skb->h.raw = skb->data + hdr_len; 54 memmove(skb->data, iph, hdr_len); 55 return; 56 } 57 58 skb->nh.raw = skb->data; 59 top_iph = skb->nh.ipv6h; 60 skb->nh.raw = &top_iph->nexthdr; 61 skb->h.ipv6h = top_iph + 1; 62 63 top_iph->version = 6; 64 top_iph->priority = iph->priority; 65 top_iph->flow_lbl[0] = iph->flow_lbl[0]; 66 top_iph->flow_lbl[1] = iph->flow_lbl[1]; 67 top_iph->flow_lbl[2] = iph->flow_lbl[2]; 68 dsfield = ipv6_get_dsfield(top_iph); 69 dsfield = INET_ECN_encapsulate(dsfield, dsfield); 70 if (x->props.flags & XFRM_STATE_NOECN) 71 dsfield &= ~INET_ECN_MASK; 72 ipv6_change_dsfield(top_iph, 0, dsfield); 73 top_iph->nexthdr = IPPROTO_IPV6; 74 top_iph->hop_limit = dst_metric(dst->child, RTAX_HOPLIMIT); 75 ipv6_addr_copy(&top_iph->saddr, (struct in6_addr *)&x->props.saddr); 76 ipv6_addr_copy(&top_iph->daddr, (struct in6_addr *)&x->id.daddr); 77 } 78 79 static int xfrm6_tunnel_check_size(struct sk_buff *skb) 80 { 81 int mtu, ret = 0; 82 struct dst_entry *dst = skb->dst; 83 84 mtu = dst_mtu(dst); 85 if (mtu < IPV6_MIN_MTU) 86 mtu = IPV6_MIN_MTU; 87 88 if (skb->len > mtu) { 89 skb->dev = dst->dev; 90 icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu, skb->dev); 91 ret = -EMSGSIZE; 92 } 93 94 return ret; 95 } 96 97 static int xfrm6_output_one(struct sk_buff *skb) 98 { 99 struct dst_entry *dst = skb->dst; 100 struct xfrm_state *x = dst->xfrm; 101 int err; 102 103 if (skb->ip_summed == CHECKSUM_HW) { 104 err = skb_checksum_help(skb, 0); 105 if (err) 106 goto error_nolock; 107 } 108 109 if (x->props.mode) { 110 err = xfrm6_tunnel_check_size(skb); 111 if (err) 112 goto error_nolock; 113 } 114 115 do { 116 spin_lock_bh(&x->lock); 117 err = xfrm_state_check(x, skb); 118 if (err) 119 goto error; 120 121 xfrm6_encap(skb); 122 123 err = x->type->output(x, skb); 124 if (err) 125 goto error; 126 127 x->curlft.bytes += skb->len; 128 x->curlft.packets++; 129 130 spin_unlock_bh(&x->lock); 131 132 skb->nh.raw = skb->data; 133 134 if (!(skb->dst = dst_pop(dst))) { 135 err = -EHOSTUNREACH; 136 goto error_nolock; 137 } 138 dst = skb->dst; 139 x = dst->xfrm; 140 } while (x && !x->props.mode); 141 142 IP6CB(skb)->flags |= IP6SKB_XFRM_TRANSFORMED; 143 err = 0; 144 145 out_exit: 146 return err; 147 error: 148 spin_unlock_bh(&x->lock); 149 error_nolock: 150 kfree_skb(skb); 151 goto out_exit; 152 } 153 154 static int xfrm6_output_finish(struct sk_buff *skb) 155 { 156 int err; 157 158 while (likely((err = xfrm6_output_one(skb)) == 0)) { 159 nf_reset(skb); 160 161 err = nf_hook(PF_INET6, NF_IP6_LOCAL_OUT, &skb, NULL, 162 skb->dst->dev, dst_output); 163 if (unlikely(err != 1)) 164 break; 165 166 if (!skb->dst->xfrm) 167 return dst_output(skb); 168 169 err = nf_hook(PF_INET6, NF_IP6_POST_ROUTING, &skb, NULL, 170 skb->dst->dev, xfrm6_output_finish); 171 if (unlikely(err != 1)) 172 break; 173 } 174 175 return err; 176 } 177 178 int xfrm6_output(struct sk_buff *skb) 179 { 180 return NF_HOOK(PF_INET6, NF_IP6_POST_ROUTING, skb, NULL, skb->dst->dev, 181 xfrm6_output_finish); 182 } 183