Пример #1
0
static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
{
	struct sock *sk=icmp_socket->sk;
	struct ipcm_cookie ipc;
	struct rtable *rt = (struct rtable*)skb->dst;
	u32 daddr;

	if (ip_options_echo(&icmp_param->replyopts, skb))
		return;

	icmp_param->icmph.checksum=0;
	icmp_param->csum=0;
	icmp_out_count(icmp_param->icmph.type);

	sk->ip_tos = skb->nh.iph->tos;
	daddr = ipc.addr = rt->rt_src;
	ipc.opt = &icmp_param->replyopts;
	if (ipc.opt->srr)
		daddr = icmp_param->replyopts.faddr;
	if (ip_route_output(&rt, daddr, rt->rt_spec_dst, RT_TOS(skb->nh.iph->tos), 0))
		return;
	if (icmpv4_xrlim_allow(rt, icmp_param->icmph.type, 
			       icmp_param->icmph.code)) { 
		ip_build_xmit(sk, icmp_glue_bits, icmp_param, 
			      icmp_param->data_len+sizeof(struct icmphdr),
			      &ipc, rt, MSG_DONTWAIT);
	}
	ip_rt_put(rt);
}
Пример #2
0
void icmp_send(struct sk_buff *skb_in, int type, int code, unsigned long info)
{
	struct iphdr *iph;
	struct icmphdr *icmph;
	int room;
	struct icmp_bxm icmp_param;
	struct rtable *rt = (struct rtable*)skb_in->dst;
	struct ipcm_cookie ipc;
	u32 saddr;
	u8  tos;
	
	/*
	 *	Find the original header
	 */
	 
	iph = skb_in->nh.iph;
	
	/*
	 *	No replies to physical multicast/broadcast
	 */
	 
	if (skb_in->pkt_type!=PACKET_HOST)
		return;
		
	/*
	 *	Now check at the protocol level
	 */
	if (!rt) {
		if (sysctl_ip_always_defrag == 0 &&
		    net_ratelimit())
			printk(KERN_DEBUG "icmp_send: destinationless packet\n");
		return;
	}
	if (rt->rt_flags&(RTCF_BROADCAST|RTCF_MULTICAST))
		return;
	 
		
	/*
	 *	Only reply to fragment 0. We byte re-order the constant
	 *	mask for efficiency.
	 */
	 
	if (iph->frag_off&htons(IP_OFFSET))
		return;
		
	/* 
	 *	If we send an ICMP error to an ICMP error a mess would result..
	 */
	 
	if (icmp_pointers[type].error) {
		/*
		 *	We are an error, check if we are replying to an ICMP error
		 */
		 
		if (iph->protocol==IPPROTO_ICMP) {
			icmph = (struct icmphdr *)((char *)iph + (iph->ihl<<2));
			/*
			 *	Assume any unknown ICMP type is an error. This isn't
			 *	specified by the RFC, but think about it..
			 */
			if (icmph->type>NR_ICMP_TYPES || icmp_pointers[icmph->type].error)
				return;
		}
	}


	/*
	 *	Construct source address and options.
	 */

#ifdef CONFIG_IP_ROUTE_NAT	
	/*
	 *	Restore original addresses if packet has been translated.
	 */
	if (rt->rt_flags&RTCF_NAT && IPCB(skb_in)->flags&IPSKB_TRANSLATED) {
		iph->daddr = rt->key.dst;
		iph->saddr = rt->key.src;
	}
#endif
#ifdef CONFIG_IP_MASQUERADE
	if (type==ICMP_DEST_UNREACH && IPCB(skb_in)->flags&IPSKB_MASQUERADED) {
			ip_fw_unmasq_icmp(skb_in);
	}
#endif

	saddr = iph->daddr;
	if (!(rt->rt_flags & RTCF_LOCAL))
		saddr = 0;

	tos = icmp_pointers[type].error ?
		((iph->tos & IPTOS_TOS_MASK) | IPTOS_PREC_INTERNETCONTROL) :
			iph->tos;

	/* XXX: use a more aggressive expire for routes created by 
	 * this call (not longer than the rate limit timeout). 
	 * It could be also worthwhile to not put them into ipv4
	 * fast routing cache at first. Otherwise an attacker can
	 * grow the routing table.
	 */
	if (ip_route_output(&rt, iph->saddr, saddr, RT_TOS(tos), 0))
		return;
	
	if (ip_options_echo(&icmp_param.replyopts, skb_in)) 
		goto ende;


	/*
	 *	Prepare data for ICMP header.
	 */

	icmp_param.icmph.type=type;
	icmp_param.icmph.code=code;
	icmp_param.icmph.un.gateway = info;
	icmp_param.icmph.checksum=0;
	icmp_param.csum=0;
	icmp_param.data_ptr=iph;
	icmp_out_count(icmp_param.icmph.type);
	icmp_socket->sk->ip_tos = tos;
	ipc.addr = iph->saddr;
	ipc.opt = &icmp_param.replyopts;
	if (icmp_param.replyopts.srr) {
		ip_rt_put(rt);
		if (ip_route_output(&rt, icmp_param.replyopts.faddr, saddr, RT_TOS(tos), 0))
			return;
	}

	if (!icmpv4_xrlim_allow(rt, type, code))
		goto ende;

	/* RFC says return as much as we can without exceeding 576 bytes. */

	room = rt->u.dst.pmtu;
	if (room > 576)
		room = 576;
	room -= sizeof(struct iphdr) + icmp_param.replyopts.optlen;
	room -= sizeof(struct icmphdr);

	icmp_param.data_len=(iph->ihl<<2)+skb_in->len;
	if (icmp_param.data_len > room)
		icmp_param.data_len = room;
	
	ip_build_xmit(icmp_socket->sk, icmp_glue_bits, &icmp_param, 
		icmp_param.data_len+sizeof(struct icmphdr),
		&ipc, rt, MSG_DONTWAIT);

ende:
	ip_rt_put(rt);
}