net/netfilter/nf_conntrack_proto_udp.c

   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  * 16 Dec 2003: Yasuyuki Kozakai @USAGI <yasuyuki.kozakai@toshiba.co.jp>
   9  *      - enable working with Layer 3 protocol independent connection tracking.
  10  *
  11  * Derived from net/ipv4/netfilter/ip_conntrack_proto_udp.c
  12  */
  13
  14 #include <linux/types.h>
  15 #include <linux/sched.h>
  16 #include <linux/timer.h>
  17 #include <linux/module.h>
  18 #include <linux/netfilter.h>
  19 #include <linux/udp.h>
  20 #include <linux/seq_file.h>
  21 #include <linux/skbuff.h>
  22 #include <linux/ipv6.h>
  23 #include <net/ip6_checksum.h>
  24 #include <net/checksum.h>
  25 #include <linux/netfilter.h>
  26 #include <linux/netfilter_ipv4.h>
  27 #include <linux/netfilter_ipv6.h>
  28 #include <net/netfilter/nf_conntrack_protocol.h>
  29
  30 unsigned int nf_ct_udp_timeout = 30*HZ;
  31 unsigned int nf_ct_udp_timeout_stream = 180*HZ;
  32
  33 static int udp_pkt_to_tuple(const struct sk_buff *skb,
  34                              unsigned int dataoff,
  35                              struct nf_conntrack_tuple *tuple)
  36 {
  37         struct udphdr _hdr, *hp;
  38
  39         /* Actually only need first 8 bytes. */
  40         hp = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
  41         if (hp == NULL)
  42                 return 0;
  43
  44         tuple->src.u.udp.port = hp->source;
  45         tuple->dst.u.udp.port = hp->dest;
  46
  47         return 1;
  48 }
  49
  50 static int udp_invert_tuple(struct nf_conntrack_tuple *tuple,
  51                             const struct nf_conntrack_tuple *orig)
  52 {
  53         tuple->src.u.udp.port = orig->dst.u.udp.port;
  54         tuple->dst.u.udp.port = orig->src.u.udp.port;
  55         return 1;
  56 }
  57
  58 /* Print out the per-protocol part of the tuple. */
  59 static int udp_print_tuple(struct seq_file *s,
  60                            const struct nf_conntrack_tuple *tuple)
  61 {
  62         return seq_printf(s, "sport=%hu dport=%hu ",
  63                           ntohs(tuple->src.u.udp.port),
  64                           ntohs(tuple->dst.u.udp.port));
  65 }
  66
  67 /* Print out the private part of the conntrack. */
  68 static int udp_print_conntrack(struct seq_file *s,
  69                                const struct nf_conn *conntrack)
  70 {
  71         return 0;
  72 }
  73
  74 /* Returns verdict for packet, and may modify conntracktype */
  75 static int udp_packet(struct nf_conn *conntrack,
  76                       const struct sk_buff *skb,
  77                       unsigned int dataoff,
  78                       enum ip_conntrack_info ctinfo,
  79                       int pf,
  80                       unsigned int hooknum)
  81 {
  82         /* If we've seen traffic both ways, this is some kind of UDP
  83            stream.  Extend timeout. */
  84         if (test_bit(IPS_SEEN_REPLY_BIT, &conntrack->status)) {
  85                 nf_ct_refresh_acct(conntrack, ctinfo, skb,
  86                                    nf_ct_udp_timeout_stream);
  87                 /* Also, more likely to be important, and not a probe */
  88                 if (!test_and_set_bit(IPS_ASSURED_BIT, &conntrack->status))
  89                         nf_conntrack_event_cache(IPCT_STATUS, skb);
  90         } else
  91                 nf_ct_refresh_acct(conntrack, ctinfo, skb, nf_ct_udp_timeout);
  92
  93         return NF_ACCEPT;
  94 }
  95
  96 /* Called when a new connection for this protocol found. */
  97 static int udp_new(struct nf_conn *conntrack, const struct sk_buff *skb,
  98                    unsigned int dataoff)
  99 {
 100         return 1;
 101 }
 102
 103 static int udp_error(struct sk_buff *skb, unsigned int dataoff,
 104                      enum ip_conntrack_info *ctinfo,
 105                      int pf,
 106                      unsigned int hooknum)
 107 {
 108         unsigned int udplen = skb->len - dataoff;
 109         struct udphdr _hdr, *hdr;
 110
 111         /* Header is too small? */
 112         hdr = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
 113         if (hdr == NULL) {
 114                 if (LOG_INVALID(IPPROTO_UDP))
 115                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 116                                       "nf_ct_udp: short packet ");
 117                 return -NF_ACCEPT;
 118         }
 119
 120         /* Truncated/malformed packets */
 121         if (ntohs(hdr->len) > udplen || ntohs(hdr->len) < sizeof(*hdr)) {
 122                 if (LOG_INVALID(IPPROTO_UDP))
 123                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 124                                 "nf_ct_udp: truncated/malformed packet ");
 125                 return -NF_ACCEPT;
 126         }
 127
 128         /* Packet with no checksum */
 129         if (!hdr->check)
 130                 return NF_ACCEPT;
 131
 132         /* Checksum invalid? Ignore.
 133          * We skip checking packets on the outgoing path
 134          * because the semantic of CHECKSUM_HW is different there
 135          * and moreover root might send raw packets.
 136          * FIXME: Source route IP option packets --RR */
 137         if (nf_conntrack_checksum &&
 138             ((pf == PF_INET && hooknum == NF_IP_PRE_ROUTING) ||
 139              (pf == PF_INET6 && hooknum == NF_IP6_PRE_ROUTING)) &&
 140             nf_checksum(skb, hooknum, dataoff, IPPROTO_UDP, pf)) {
 141                 if (LOG_INVALID(IPPROTO_UDP))
 142                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 143                                 "nf_ct_udp: bad UDP checksum ");
 144                 return -NF_ACCEPT;
 145         }
 146
 147         return NF_ACCEPT;
 148 }
 149
 150 struct nf_conntrack_protocol nf_conntrack_protocol_udp4 =
 151 {
 152         .l3proto                = PF_INET,
 153         .proto                  = IPPROTO_UDP,
 154         .name                   = "udp",
 155         .pkt_to_tuple           = udp_pkt_to_tuple,
 156         .invert_tuple           = udp_invert_tuple,
 157         .print_tuple            = udp_print_tuple,
 158         .print_conntrack        = udp_print_conntrack,
 159         .packet                 = udp_packet,
 160         .new                    = udp_new,
 161         .error                  = udp_error,
 162 #if defined(CONFIG_NF_CT_NETLINK) || \
 163     defined(CONFIG_NF_CT_NETLINK_MODULE)
 164         .tuple_to_nfattr        = nf_ct_port_tuple_to_nfattr,
 165         .nfattr_to_tuple        = nf_ct_port_nfattr_to_tuple,
 166 #endif
 167 };
 168
 169 struct nf_conntrack_protocol nf_conntrack_protocol_udp6 =
 170 {
 171         .l3proto                = PF_INET6,
 172         .proto                  = IPPROTO_UDP,
 173         .name                   = "udp",
 174         .pkt_to_tuple           = udp_pkt_to_tuple,
 175         .invert_tuple           = udp_invert_tuple,
 176         .print_tuple            = udp_print_tuple,
 177         .print_conntrack        = udp_print_conntrack,
 178         .packet                 = udp_packet,
 179         .new                    = udp_new,
 180         .error                  = udp_error,
 181 #if defined(CONFIG_NF_CT_NETLINK) || \
 182     defined(CONFIG_NF_CT_NETLINK_MODULE)
 183         .tuple_to_nfattr        = nf_ct_port_tuple_to_nfattr,
 184         .nfattr_to_tuple        = nf_ct_port_nfattr_to_tuple,
 185 #endif
 186 };
 187
 188 EXPORT_SYMBOL(nf_conntrack_protocol_udp4);
 189 EXPORT_SYMBOL(nf_conntrack_protocol_udp6);