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/timer.h>
  16 #include <linux/module.h>
  17 #include <linux/netfilter.h>
  18 #include <linux/udp.h>
  19 #include <linux/seq_file.h>
  20 #include <linux/skbuff.h>
  21 #include <linux/ipv6.h>
  22 #include <net/ip6_checksum.h>
  23 #include <net/checksum.h>
  24
  25 #include <linux/netfilter.h>
  26 #include <linux/netfilter_ipv4.h>
  27 #include <linux/netfilter_ipv6.h>
  28 #include <net/netfilter/nf_conntrack_l4proto.h>
  29 #include <net/netfilter/nf_conntrack_ecache.h>
  30
  31 static unsigned int nf_ct_udp_timeout __read_mostly = 30*HZ;
  32 static unsigned int nf_ct_udp_timeout_stream __read_mostly = 180*HZ;
  33
  34 static int udp_pkt_to_tuple(const struct sk_buff *skb,
  35                              unsigned int dataoff,
  36                              struct nf_conntrack_tuple *tuple)
  37 {
  38         struct udphdr _hdr, *hp;
  39
  40         /* Actually only need first 8 bytes. */
  41         hp = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
  42         if (hp == NULL)
  43                 return 0;
  44
  45         tuple->src.u.udp.port = hp->source;
  46         tuple->dst.u.udp.port = hp->dest;
  47
  48         return 1;
  49 }
  50
  51 static int udp_invert_tuple(struct nf_conntrack_tuple *tuple,
  52                             const struct nf_conntrack_tuple *orig)
  53 {
  54         tuple->src.u.udp.port = orig->dst.u.udp.port;
  55         tuple->dst.u.udp.port = orig->src.u.udp.port;
  56         return 1;
  57 }
  58
  59 /* Print out the per-protocol part of the tuple. */
  60 static int udp_print_tuple(struct seq_file *s,
  61                            const struct nf_conntrack_tuple *tuple)
  62 {
  63         return seq_printf(s, "sport=%hu dport=%hu ",
  64                           ntohs(tuple->src.u.udp.port),
  65                           ntohs(tuple->dst.u.udp.port));
  66 }
  67
  68 /* Print out the private part of the conntrack. */
  69 static int udp_print_conntrack(struct seq_file *s,
  70                                const struct nf_conn *conntrack)
  71 {
  72         return 0;
  73 }
  74
  75 /* Returns verdict for packet, and may modify conntracktype */
  76 static int udp_packet(struct nf_conn *conntrack,
  77                       const struct sk_buff *skb,
  78                       unsigned int dataoff,
  79                       enum ip_conntrack_info ctinfo,
  80                       int pf,
  81                       unsigned int hooknum)
  82 {
  83         /* If we've seen traffic both ways, this is some kind of UDP
  84            stream.  Extend timeout. */
  85         if (test_bit(IPS_SEEN_REPLY_BIT, &conntrack->status)) {
  86                 nf_ct_refresh_acct(conntrack, ctinfo, skb,
  87                                    nf_ct_udp_timeout_stream);
  88                 /* Also, more likely to be important, and not a probe */
  89                 if (!test_and_set_bit(IPS_ASSURED_BIT, &conntrack->status))
  90                         nf_conntrack_event_cache(IPCT_STATUS, skb);
  91         } else
  92                 nf_ct_refresh_acct(conntrack, ctinfo, skb, nf_ct_udp_timeout);
  93
  94         return NF_ACCEPT;
  95 }
  96
  97 /* Called when a new connection for this protocol found. */
  98 static int udp_new(struct nf_conn *conntrack, const struct sk_buff *skb,
  99                    unsigned int dataoff)
 100 {
 101         return 1;
 102 }
 103
 104 static int udp_error(struct sk_buff *skb, unsigned int dataoff,
 105                      enum ip_conntrack_info *ctinfo,
 106                      int pf,
 107                      unsigned int hooknum)
 108 {
 109         unsigned int udplen = skb->len - dataoff;
 110         struct udphdr _hdr, *hdr;
 111
 112         /* Header is too small? */
 113         hdr = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
 114         if (hdr == NULL) {
 115                 if (LOG_INVALID(IPPROTO_UDP))
 116                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 117                                       "nf_ct_udp: short packet ");
 118                 return -NF_ACCEPT;
 119         }
 120
 121         /* Truncated/malformed packets */
 122         if (ntohs(hdr->len) > udplen || ntohs(hdr->len) < sizeof(*hdr)) {
 123                 if (LOG_INVALID(IPPROTO_UDP))
 124                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 125                                 "nf_ct_udp: truncated/malformed packet ");
 126                 return -NF_ACCEPT;
 127         }
 128
 129         /* Packet with no checksum */
 130         if (!hdr->check)
 131                 return NF_ACCEPT;
 132
 133         /* Checksum invalid? Ignore.
 134          * We skip checking packets on the outgoing path
 135          * because the checksum is assumed to be correct.
 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 #ifdef CONFIG_SYSCTL
 151 static unsigned int udp_sysctl_table_users;
 152 static struct ctl_table_header *udp_sysctl_header;
 153 static struct ctl_table udp_sysctl_table[] = {
 154         {
 155                 .ctl_name       = NET_NF_CONNTRACK_UDP_TIMEOUT,
 156                 .procname       = "nf_conntrack_udp_timeout",
 157                 .data           = &nf_ct_udp_timeout,
 158                 .maxlen         = sizeof(unsigned int),
 159                 .mode           = 0644,
 160                 .proc_handler   = &proc_dointvec_jiffies,
 161         },
 162         {
 163                 .ctl_name       = NET_NF_CONNTRACK_UDP_TIMEOUT_STREAM,
 164                 .procname       = "nf_conntrack_udp_timeout_stream",
 165                 .data           = &nf_ct_udp_timeout_stream,
 166                 .maxlen         = sizeof(unsigned int),
 167                 .mode           = 0644,
 168                 .proc_handler   = &proc_dointvec_jiffies,
 169         },
 170         {
 171                 .ctl_name       = 0
 172         }
 173 };
 174 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
 175 static struct ctl_table udp_compat_sysctl_table[] = {
 176         {
 177                 .ctl_name       = NET_IPV4_NF_CONNTRACK_UDP_TIMEOUT,
 178                 .procname       = "ip_conntrack_udp_timeout",
 179                 .data           = &nf_ct_udp_timeout,
 180                 .maxlen         = sizeof(unsigned int),
 181                 .mode           = 0644,
 182                 .proc_handler   = &proc_dointvec_jiffies,
 183         },
 184         {
 185                 .ctl_name       = NET_IPV4_NF_CONNTRACK_UDP_TIMEOUT_STREAM,
 186                 .procname       = "ip_conntrack_udp_timeout_stream",
 187                 .data           = &nf_ct_udp_timeout_stream,
 188                 .maxlen         = sizeof(unsigned int),
 189                 .mode           = 0644,
 190                 .proc_handler   = &proc_dointvec_jiffies,
 191         },
 192         {
 193                 .ctl_name       = 0
 194         }
 195 };
 196 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
 197 #endif /* CONFIG_SYSCTL */
 198
 199 struct nf_conntrack_l4proto nf_conntrack_l4proto_udp4 =
 200 {
 201         .l3proto                = PF_INET,
 202         .l4proto                = IPPROTO_UDP,
 203         .name                   = "udp",
 204         .pkt_to_tuple           = udp_pkt_to_tuple,
 205         .invert_tuple           = udp_invert_tuple,
 206         .print_tuple            = udp_print_tuple,
 207         .print_conntrack        = udp_print_conntrack,
 208         .packet                 = udp_packet,
 209         .new                    = udp_new,
 210         .error                  = udp_error,
 211 #if defined(CONFIG_NF_CT_NETLINK) || \
 212     defined(CONFIG_NF_CT_NETLINK_MODULE)
 213         .tuple_to_nfattr        = nf_ct_port_tuple_to_nfattr,
 214         .nfattr_to_tuple        = nf_ct_port_nfattr_to_tuple,
 215 #endif
 216 #ifdef CONFIG_SYSCTL
 217         .ctl_table_users        = &udp_sysctl_table_users,
 218         .ctl_table_header       = &udp_sysctl_header,
 219         .ctl_table              = udp_sysctl_table,
 220 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
 221         .ctl_compat_table       = udp_compat_sysctl_table,
 222 #endif
 223 #endif
 224 };
 225 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_udp4);
 226
 227 struct nf_conntrack_l4proto nf_conntrack_l4proto_udp6 =
 228 {
 229         .l3proto                = PF_INET6,
 230         .l4proto                = IPPROTO_UDP,
 231         .name                   = "udp",
 232         .pkt_to_tuple           = udp_pkt_to_tuple,
 233         .invert_tuple           = udp_invert_tuple,
 234         .print_tuple            = udp_print_tuple,
 235         .print_conntrack        = udp_print_conntrack,
 236         .packet                 = udp_packet,
 237         .new                    = udp_new,
 238         .error                  = udp_error,
 239 #if defined(CONFIG_NF_CT_NETLINK) || \
 240     defined(CONFIG_NF_CT_NETLINK_MODULE)
 241         .tuple_to_nfattr        = nf_ct_port_tuple_to_nfattr,
 242         .nfattr_to_tuple        = nf_ct_port_nfattr_to_tuple,
 243 #endif
 244 #ifdef CONFIG_SYSCTL
 245         .ctl_table_users        = &udp_sysctl_table_users,
 246         .ctl_table_header       = &udp_sysctl_header,
 247         .ctl_table              = udp_sysctl_table,
 248 #endif
 249 };
 250 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_udp6);