147 lines
4.1 KiB
C
147 lines
4.1 KiB
C
/* (C) 1999-2001 Paul `Rusty' Russell
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* (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/types.h>
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#include <linux/sched.h>
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#include <linux/timer.h>
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#include <linux/netfilter.h>
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#include <linux/in.h>
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#include <linux/udp.h>
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#include <linux/seq_file.h>
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#include <net/checksum.h>
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#include <linux/netfilter.h>
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#include <linux/netfilter_ipv4.h>
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#include <linux/netfilter_ipv4/ip_conntrack_protocol.h>
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unsigned long ip_ct_udp_timeout = 30*HZ;
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unsigned long ip_ct_udp_timeout_stream = 180*HZ;
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static int udp_pkt_to_tuple(const struct sk_buff *skb,
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unsigned int dataoff,
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struct ip_conntrack_tuple *tuple)
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{
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struct udphdr _hdr, *hp;
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/* Actually only need first 8 bytes. */
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hp = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
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if (hp == NULL)
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return 0;
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tuple->src.u.udp.port = hp->source;
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tuple->dst.u.udp.port = hp->dest;
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return 1;
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}
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static int udp_invert_tuple(struct ip_conntrack_tuple *tuple,
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const struct ip_conntrack_tuple *orig)
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{
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tuple->src.u.udp.port = orig->dst.u.udp.port;
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tuple->dst.u.udp.port = orig->src.u.udp.port;
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return 1;
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}
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/* Print out the per-protocol part of the tuple. */
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static int udp_print_tuple(struct seq_file *s,
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const struct ip_conntrack_tuple *tuple)
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{
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return seq_printf(s, "sport=%hu dport=%hu ",
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ntohs(tuple->src.u.udp.port),
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ntohs(tuple->dst.u.udp.port));
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}
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/* Print out the private part of the conntrack. */
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static int udp_print_conntrack(struct seq_file *s,
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const struct ip_conntrack *conntrack)
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{
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return 0;
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}
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/* Returns verdict for packet, and may modify conntracktype */
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static int udp_packet(struct ip_conntrack *conntrack,
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const struct sk_buff *skb,
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enum ip_conntrack_info ctinfo)
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{
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/* If we've seen traffic both ways, this is some kind of UDP
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stream. Extend timeout. */
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if (test_bit(IPS_SEEN_REPLY_BIT, &conntrack->status)) {
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ip_ct_refresh_acct(conntrack, ctinfo, skb,
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ip_ct_udp_timeout_stream);
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/* Also, more likely to be important, and not a probe */
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set_bit(IPS_ASSURED_BIT, &conntrack->status);
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} else
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ip_ct_refresh_acct(conntrack, ctinfo, skb, ip_ct_udp_timeout);
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return NF_ACCEPT;
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}
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/* Called when a new connection for this protocol found. */
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static int udp_new(struct ip_conntrack *conntrack, const struct sk_buff *skb)
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{
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return 1;
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}
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static int udp_error(struct sk_buff *skb, enum ip_conntrack_info *ctinfo,
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unsigned int hooknum)
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{
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struct iphdr *iph = skb->nh.iph;
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unsigned int udplen = skb->len - iph->ihl * 4;
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struct udphdr _hdr, *hdr;
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/* Header is too small? */
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hdr = skb_header_pointer(skb, iph->ihl*4, sizeof(_hdr), &_hdr);
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if (hdr == NULL) {
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if (LOG_INVALID(IPPROTO_UDP))
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nf_log_packet(PF_INET, 0, skb, NULL, NULL,
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"ip_ct_udp: short packet ");
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return -NF_ACCEPT;
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}
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/* Truncated/malformed packets */
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if (ntohs(hdr->len) > udplen || ntohs(hdr->len) < sizeof(*hdr)) {
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if (LOG_INVALID(IPPROTO_UDP))
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nf_log_packet(PF_INET, 0, skb, NULL, NULL,
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"ip_ct_udp: truncated/malformed packet ");
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return -NF_ACCEPT;
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}
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/* Packet with no checksum */
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if (!hdr->check)
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return NF_ACCEPT;
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/* Checksum invalid? Ignore.
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* We skip checking packets on the outgoing path
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* because the semantic of CHECKSUM_HW is different there
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* and moreover root might send raw packets.
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* FIXME: Source route IP option packets --RR */
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if (hooknum == NF_IP_PRE_ROUTING
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&& csum_tcpudp_magic(iph->saddr, iph->daddr, udplen, IPPROTO_UDP,
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skb->ip_summed == CHECKSUM_HW ? skb->csum
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: skb_checksum(skb, iph->ihl*4, udplen, 0))) {
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if (LOG_INVALID(IPPROTO_UDP))
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nf_log_packet(PF_INET, 0, skb, NULL, NULL,
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"ip_ct_udp: bad UDP checksum ");
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return -NF_ACCEPT;
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}
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return NF_ACCEPT;
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}
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struct ip_conntrack_protocol ip_conntrack_protocol_udp =
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{
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.proto = IPPROTO_UDP,
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.name = "udp",
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.pkt_to_tuple = udp_pkt_to_tuple,
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.invert_tuple = udp_invert_tuple,
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.print_tuple = udp_print_tuple,
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.print_conntrack = udp_print_conntrack,
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.packet = udp_packet,
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.new = udp_new,
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.error = udp_error,
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};
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