142 lines
3.1 KiB
C
142 lines
3.1 KiB
C
/*
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* xfrm4_output.c - Common IPsec encapsulation code for IPv4.
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* Copyright (c) 2004 Herbert Xu <herbert@gondor.apana.org.au>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/skbuff.h>
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#include <linux/spinlock.h>
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#include <net/inet_ecn.h>
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#include <net/ip.h>
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#include <net/xfrm.h>
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#include <net/icmp.h>
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/* Add encapsulation header.
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*
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* In transport mode, the IP header will be moved forward to make space
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* for the encapsulation header.
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*
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* In tunnel mode, the top IP header will be constructed per RFC 2401.
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* The following fields in it shall be filled in by x->type->output:
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* tot_len
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* check
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*
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* On exit, skb->h will be set to the start of the payload to be processed
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* by x->type->output and skb->nh will be set to the top IP header.
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*/
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static void xfrm4_encap(struct sk_buff *skb)
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{
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struct dst_entry *dst = skb->dst;
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struct xfrm_state *x = dst->xfrm;
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struct iphdr *iph, *top_iph;
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iph = skb->nh.iph;
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skb->h.ipiph = iph;
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skb->nh.raw = skb_push(skb, x->props.header_len);
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top_iph = skb->nh.iph;
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if (!x->props.mode) {
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skb->h.raw += iph->ihl*4;
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memmove(top_iph, iph, iph->ihl*4);
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return;
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}
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top_iph->ihl = 5;
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top_iph->version = 4;
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/* DS disclosed */
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top_iph->tos = INET_ECN_encapsulate(iph->tos, iph->tos);
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if (x->props.flags & XFRM_STATE_NOECN)
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IP_ECN_clear(top_iph);
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top_iph->frag_off = iph->frag_off & htons(IP_DF);
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if (!top_iph->frag_off)
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__ip_select_ident(top_iph, dst, 0);
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top_iph->ttl = dst_metric(dst->child, RTAX_HOPLIMIT);
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top_iph->saddr = x->props.saddr.a4;
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top_iph->daddr = x->id.daddr.a4;
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top_iph->protocol = IPPROTO_IPIP;
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memset(&(IPCB(skb)->opt), 0, sizeof(struct ip_options));
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}
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static int xfrm4_tunnel_check_size(struct sk_buff *skb)
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{
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int mtu, ret = 0;
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struct dst_entry *dst;
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struct iphdr *iph = skb->nh.iph;
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if (IPCB(skb)->flags & IPSKB_XFRM_TUNNEL_SIZE)
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goto out;
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IPCB(skb)->flags |= IPSKB_XFRM_TUNNEL_SIZE;
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if (!(iph->frag_off & htons(IP_DF)) || skb->local_df)
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goto out;
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dst = skb->dst;
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mtu = dst_mtu(dst);
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if (skb->len > mtu) {
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icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, htonl(mtu));
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ret = -EMSGSIZE;
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}
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out:
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return ret;
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}
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int xfrm4_output(struct sk_buff *skb)
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{
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struct dst_entry *dst = skb->dst;
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struct xfrm_state *x = dst->xfrm;
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int err;
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if (skb->ip_summed == CHECKSUM_HW) {
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err = skb_checksum_help(skb, 0);
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if (err)
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goto error_nolock;
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}
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if (x->props.mode) {
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err = xfrm4_tunnel_check_size(skb);
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if (err)
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goto error_nolock;
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}
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spin_lock_bh(&x->lock);
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err = xfrm_state_check(x, skb);
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if (err)
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goto error;
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xfrm4_encap(skb);
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err = x->type->output(x, skb);
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if (err)
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goto error;
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x->curlft.bytes += skb->len;
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x->curlft.packets++;
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spin_unlock_bh(&x->lock);
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if (!(skb->dst = dst_pop(dst))) {
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err = -EHOSTUNREACH;
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goto error_nolock;
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}
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err = NET_XMIT_BYPASS;
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out_exit:
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return err;
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error:
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spin_unlock_bh(&x->lock);
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error_nolock:
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kfree_skb(skb);
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goto out_exit;
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}
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