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