Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame^] | 1 | /* (C) 1999-2001 Paul `Rusty' Russell |
| 2 | * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org> |
| 3 | * |
| 4 | * This program is free software; you can redistribute it and/or modify |
| 5 | * it under the terms of the GNU General Public License version 2 as |
| 6 | * published by the Free Software Foundation. |
| 7 | */ |
| 8 | |
| 9 | #include <linux/types.h> |
| 10 | #include <linux/sched.h> |
| 11 | #include <linux/timer.h> |
| 12 | #include <linux/netfilter.h> |
| 13 | #include <linux/in.h> |
| 14 | #include <linux/udp.h> |
| 15 | #include <linux/seq_file.h> |
| 16 | #include <net/checksum.h> |
| 17 | #include <linux/netfilter.h> |
| 18 | #include <linux/netfilter_ipv4.h> |
| 19 | #include <linux/netfilter_ipv4/ip_conntrack_protocol.h> |
| 20 | |
| 21 | unsigned long ip_ct_udp_timeout = 30*HZ; |
| 22 | unsigned long ip_ct_udp_timeout_stream = 180*HZ; |
| 23 | |
| 24 | static int udp_pkt_to_tuple(const struct sk_buff *skb, |
| 25 | unsigned int dataoff, |
| 26 | struct ip_conntrack_tuple *tuple) |
| 27 | { |
| 28 | struct udphdr _hdr, *hp; |
| 29 | |
| 30 | /* Actually only need first 8 bytes. */ |
| 31 | hp = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr); |
| 32 | if (hp == NULL) |
| 33 | return 0; |
| 34 | |
| 35 | tuple->src.u.udp.port = hp->source; |
| 36 | tuple->dst.u.udp.port = hp->dest; |
| 37 | |
| 38 | return 1; |
| 39 | } |
| 40 | |
| 41 | static int udp_invert_tuple(struct ip_conntrack_tuple *tuple, |
| 42 | const struct ip_conntrack_tuple *orig) |
| 43 | { |
| 44 | tuple->src.u.udp.port = orig->dst.u.udp.port; |
| 45 | tuple->dst.u.udp.port = orig->src.u.udp.port; |
| 46 | return 1; |
| 47 | } |
| 48 | |
| 49 | /* Print out the per-protocol part of the tuple. */ |
| 50 | static int udp_print_tuple(struct seq_file *s, |
| 51 | const struct ip_conntrack_tuple *tuple) |
| 52 | { |
| 53 | return seq_printf(s, "sport=%hu dport=%hu ", |
| 54 | ntohs(tuple->src.u.udp.port), |
| 55 | ntohs(tuple->dst.u.udp.port)); |
| 56 | } |
| 57 | |
| 58 | /* Print out the private part of the conntrack. */ |
| 59 | static int udp_print_conntrack(struct seq_file *s, |
| 60 | const struct ip_conntrack *conntrack) |
| 61 | { |
| 62 | return 0; |
| 63 | } |
| 64 | |
| 65 | /* Returns verdict for packet, and may modify conntracktype */ |
| 66 | static int udp_packet(struct ip_conntrack *conntrack, |
| 67 | const struct sk_buff *skb, |
| 68 | enum ip_conntrack_info ctinfo) |
| 69 | { |
| 70 | /* If we've seen traffic both ways, this is some kind of UDP |
| 71 | stream. Extend timeout. */ |
| 72 | if (test_bit(IPS_SEEN_REPLY_BIT, &conntrack->status)) { |
| 73 | ip_ct_refresh_acct(conntrack, ctinfo, skb, |
| 74 | ip_ct_udp_timeout_stream); |
| 75 | /* Also, more likely to be important, and not a probe */ |
| 76 | set_bit(IPS_ASSURED_BIT, &conntrack->status); |
| 77 | } else |
| 78 | ip_ct_refresh_acct(conntrack, ctinfo, skb, ip_ct_udp_timeout); |
| 79 | |
| 80 | return NF_ACCEPT; |
| 81 | } |
| 82 | |
| 83 | /* Called when a new connection for this protocol found. */ |
| 84 | static int udp_new(struct ip_conntrack *conntrack, const struct sk_buff *skb) |
| 85 | { |
| 86 | return 1; |
| 87 | } |
| 88 | |
| 89 | static int udp_error(struct sk_buff *skb, enum ip_conntrack_info *ctinfo, |
| 90 | unsigned int hooknum) |
| 91 | { |
| 92 | struct iphdr *iph = skb->nh.iph; |
| 93 | unsigned int udplen = skb->len - iph->ihl * 4; |
| 94 | struct udphdr _hdr, *hdr; |
| 95 | |
| 96 | /* Header is too small? */ |
| 97 | hdr = skb_header_pointer(skb, iph->ihl*4, sizeof(_hdr), &_hdr); |
| 98 | if (hdr == NULL) { |
| 99 | if (LOG_INVALID(IPPROTO_UDP)) |
| 100 | nf_log_packet(PF_INET, 0, skb, NULL, NULL, |
| 101 | "ip_ct_udp: short packet "); |
| 102 | return -NF_ACCEPT; |
| 103 | } |
| 104 | |
| 105 | /* Truncated/malformed packets */ |
| 106 | if (ntohs(hdr->len) > udplen || ntohs(hdr->len) < sizeof(*hdr)) { |
| 107 | if (LOG_INVALID(IPPROTO_UDP)) |
| 108 | nf_log_packet(PF_INET, 0, skb, NULL, NULL, |
| 109 | "ip_ct_udp: truncated/malformed packet "); |
| 110 | return -NF_ACCEPT; |
| 111 | } |
| 112 | |
| 113 | /* Packet with no checksum */ |
| 114 | if (!hdr->check) |
| 115 | return NF_ACCEPT; |
| 116 | |
| 117 | /* Checksum invalid? Ignore. |
| 118 | * We skip checking packets on the outgoing path |
| 119 | * because the semantic of CHECKSUM_HW is different there |
| 120 | * and moreover root might send raw packets. |
| 121 | * FIXME: Source route IP option packets --RR */ |
| 122 | if (hooknum == NF_IP_PRE_ROUTING |
| 123 | && csum_tcpudp_magic(iph->saddr, iph->daddr, udplen, IPPROTO_UDP, |
| 124 | skb->ip_summed == CHECKSUM_HW ? skb->csum |
| 125 | : skb_checksum(skb, iph->ihl*4, udplen, 0))) { |
| 126 | if (LOG_INVALID(IPPROTO_UDP)) |
| 127 | nf_log_packet(PF_INET, 0, skb, NULL, NULL, |
| 128 | "ip_ct_udp: bad UDP checksum "); |
| 129 | return -NF_ACCEPT; |
| 130 | } |
| 131 | |
| 132 | return NF_ACCEPT; |
| 133 | } |
| 134 | |
| 135 | struct ip_conntrack_protocol ip_conntrack_protocol_udp = |
| 136 | { |
| 137 | .proto = IPPROTO_UDP, |
| 138 | .name = "udp", |
| 139 | .pkt_to_tuple = udp_pkt_to_tuple, |
| 140 | .invert_tuple = udp_invert_tuple, |
| 141 | .print_tuple = udp_print_tuple, |
| 142 | .print_conntrack = udp_print_conntrack, |
| 143 | .packet = udp_packet, |
| 144 | .new = udp_new, |
| 145 | .error = udp_error, |
| 146 | }; |