Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * xfrm4_output.c - Common IPsec encapsulation code for IPv4. |
| 3 | * Copyright (c) 2004 Herbert Xu <herbert@gondor.apana.org.au> |
| 4 | * |
| 5 | * This program is free software; you can redistribute it and/or |
| 6 | * modify it under the terms of the GNU General Public License |
| 7 | * as published by the Free Software Foundation; either version |
| 8 | * 2 of the License, or (at your option) any later version. |
| 9 | */ |
| 10 | |
| 11 | #include <linux/skbuff.h> |
| 12 | #include <linux/spinlock.h> |
| 13 | #include <net/inet_ecn.h> |
| 14 | #include <net/ip.h> |
| 15 | #include <net/xfrm.h> |
| 16 | #include <net/icmp.h> |
| 17 | |
| 18 | /* Add encapsulation header. |
| 19 | * |
| 20 | * In transport mode, the IP header will be moved forward to make space |
| 21 | * for the encapsulation header. |
| 22 | * |
| 23 | * In tunnel mode, the top IP header will be constructed per RFC 2401. |
| 24 | * The following fields in it shall be filled in by x->type->output: |
| 25 | * tot_len |
| 26 | * check |
| 27 | * |
| 28 | * On exit, skb->h will be set to the start of the payload to be processed |
| 29 | * by x->type->output and skb->nh will be set to the top IP header. |
| 30 | */ |
| 31 | static void xfrm4_encap(struct sk_buff *skb) |
| 32 | { |
| 33 | struct dst_entry *dst = skb->dst; |
| 34 | struct xfrm_state *x = dst->xfrm; |
| 35 | struct iphdr *iph, *top_iph; |
| 36 | |
| 37 | iph = skb->nh.iph; |
| 38 | skb->h.ipiph = iph; |
| 39 | |
| 40 | skb->nh.raw = skb_push(skb, x->props.header_len); |
| 41 | top_iph = skb->nh.iph; |
| 42 | |
| 43 | if (!x->props.mode) { |
| 44 | skb->h.raw += iph->ihl*4; |
| 45 | memmove(top_iph, iph, iph->ihl*4); |
| 46 | return; |
| 47 | } |
| 48 | |
| 49 | top_iph->ihl = 5; |
| 50 | top_iph->version = 4; |
| 51 | |
| 52 | /* DS disclosed */ |
| 53 | top_iph->tos = INET_ECN_encapsulate(iph->tos, iph->tos); |
| 54 | if (x->props.flags & XFRM_STATE_NOECN) |
| 55 | IP_ECN_clear(top_iph); |
| 56 | |
| 57 | top_iph->frag_off = iph->frag_off & htons(IP_DF); |
| 58 | if (!top_iph->frag_off) |
| 59 | __ip_select_ident(top_iph, dst, 0); |
| 60 | |
| 61 | top_iph->ttl = dst_metric(dst->child, RTAX_HOPLIMIT); |
| 62 | |
| 63 | top_iph->saddr = x->props.saddr.a4; |
| 64 | top_iph->daddr = x->id.daddr.a4; |
| 65 | top_iph->protocol = IPPROTO_IPIP; |
| 66 | |
| 67 | memset(&(IPCB(skb)->opt), 0, sizeof(struct ip_options)); |
| 68 | } |
| 69 | |
| 70 | static int xfrm4_tunnel_check_size(struct sk_buff *skb) |
| 71 | { |
| 72 | int mtu, ret = 0; |
| 73 | struct dst_entry *dst; |
| 74 | struct iphdr *iph = skb->nh.iph; |
| 75 | |
| 76 | if (IPCB(skb)->flags & IPSKB_XFRM_TUNNEL_SIZE) |
| 77 | goto out; |
| 78 | |
| 79 | IPCB(skb)->flags |= IPSKB_XFRM_TUNNEL_SIZE; |
| 80 | |
| 81 | if (!(iph->frag_off & htons(IP_DF)) || skb->local_df) |
| 82 | goto out; |
| 83 | |
| 84 | dst = skb->dst; |
| 85 | mtu = dst_mtu(dst); |
| 86 | if (skb->len > mtu) { |
| 87 | icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, htonl(mtu)); |
| 88 | ret = -EMSGSIZE; |
| 89 | } |
| 90 | out: |
| 91 | return ret; |
| 92 | } |
| 93 | |
| 94 | int xfrm4_output(struct sk_buff *skb) |
| 95 | { |
| 96 | struct dst_entry *dst = skb->dst; |
| 97 | struct xfrm_state *x = dst->xfrm; |
| 98 | int err; |
| 99 | |
| 100 | if (skb->ip_summed == CHECKSUM_HW) { |
| 101 | err = skb_checksum_help(skb, 0); |
| 102 | if (err) |
| 103 | goto error_nolock; |
| 104 | } |
| 105 | |
| 106 | if (x->props.mode) { |
| 107 | err = xfrm4_tunnel_check_size(skb); |
| 108 | if (err) |
| 109 | goto error_nolock; |
| 110 | } |
| 111 | |
| 112 | spin_lock_bh(&x->lock); |
| 113 | err = xfrm_state_check(x, skb); |
| 114 | if (err) |
| 115 | goto error; |
| 116 | |
| 117 | xfrm4_encap(skb); |
| 118 | |
| 119 | err = x->type->output(x, skb); |
| 120 | if (err) |
| 121 | goto error; |
| 122 | |
| 123 | x->curlft.bytes += skb->len; |
| 124 | x->curlft.packets++; |
| 125 | |
| 126 | spin_unlock_bh(&x->lock); |
| 127 | |
| 128 | if (!(skb->dst = dst_pop(dst))) { |
| 129 | err = -EHOSTUNREACH; |
| 130 | goto error_nolock; |
| 131 | } |
| 132 | err = NET_XMIT_BYPASS; |
| 133 | |
| 134 | out_exit: |
| 135 | return err; |
| 136 | error: |
| 137 | spin_unlock_bh(&x->lock); |
| 138 | error_nolock: |
| 139 | kfree_skb(skb); |
| 140 | goto out_exit; |
| 141 | } |