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
  26 #include <linux/netfilter.h>
  27 #include <linux/netfilter_ipv4.h>
  28 #include <linux/netfilter_ipv6.h>
  29 #include <net/netfilter/nf_conntrack_l4proto.h>
  30 #include <net/netfilter/nf_conntrack_ecache.h>
  31
  32 static unsigned int nf_ct_udp_timeout __read_mostly = 30*HZ;
  33 static unsigned int nf_ct_udp_timeout_stream __read_mostly = 180*HZ;
  34
  35 static int udp_pkt_to_tuple(const struct sk_buff *skb,
  36                              unsigned int dataoff,
  37                              struct nf_conntrack_tuple *tuple)
  38 {
  39         struct udphdr _hdr, *hp;
  40
  41         /* Actually only need first 8 bytes. */
  42         hp = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
  43         if (hp == NULL)
  44                 return 0;
  45
  46         tuple->src.u.udp.port = hp->source;
  47         tuple->dst.u.udp.port = hp->dest;
  48
  49         return 1;
  50 }
  51
  52 static int udp_invert_tuple(struct nf_conntrack_tuple *tuple,
  53                             const struct nf_conntrack_tuple *orig)
  54 {
  55         tuple->src.u.udp.port = orig->dst.u.udp.port;
  56         tuple->dst.u.udp.port = orig->src.u.udp.port;
  57         return 1;
  58 }
  59
  60 /* Print out the per-protocol part of the tuple. */
  61 static int udp_print_tuple(struct seq_file *s,
  62                            const struct nf_conntrack_tuple *tuple)
  63 {
  64         return seq_printf(s, "sport=%hu dport=%hu ",
  65                           ntohs(tuple->src.u.udp.port),
  66                           ntohs(tuple->dst.u.udp.port));
  67 }
  68
  69 /* Print out the private part of the conntrack. */
  70 static int udp_print_conntrack(struct seq_file *s,
  71                                const struct nf_conn *conntrack)
  72 {
  73         return 0;
  74 }
  75
  76 /* Returns verdict for packet, and may modify conntracktype */
  77 static int udp_packet(struct nf_conn *conntrack,
  78                       const struct sk_buff *skb,
  79                       unsigned int dataoff,
  80                       enum ip_conntrack_info ctinfo,
  81                       int pf,
  82                       unsigned int hooknum)
  83 {
  84         /* If we've seen traffic both ways, this is some kind of UDP
  85            stream.  Extend timeout. */
  86         if (test_bit(IPS_SEEN_REPLY_BIT, &conntrack->status)) {
  87                 nf_ct_refresh_acct(conntrack, ctinfo, skb,
  88                                    nf_ct_udp_timeout_stream);
  89                 /* Also, more likely to be important, and not a probe */
  90                 if (!test_and_set_bit(IPS_ASSURED_BIT, &conntrack->status))
  91                         nf_conntrack_event_cache(IPCT_STATUS, skb);
  92         } else
  93                 nf_ct_refresh_acct(conntrack, ctinfo, skb, nf_ct_udp_timeout);
  94
  95         return NF_ACCEPT;
  96 }
  97
  98 /* Called when a new connection for this protocol found. */
  99 static int udp_new(struct nf_conn *conntrack, const struct sk_buff *skb,
 100                    unsigned int dataoff)
 101 {
 102         return 1;
 103 }
 104
 105 static int udp_error(struct sk_buff *skb, unsigned int dataoff,
 106                      enum ip_conntrack_info *ctinfo,
 107                      int pf,
 108                      unsigned int hooknum)
 109 {
 110         unsigned int udplen = skb->len - dataoff;
 111         struct udphdr _hdr, *hdr;
 112
 113         /* Header is too small? */
 114         hdr = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
 115         if (hdr == NULL) {
 116                 if (LOG_INVALID(IPPROTO_UDP))
 117                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 118                                       "nf_ct_udp: short packet ");
 119                 return -NF_ACCEPT;
 120         }
 121
 122         /* Truncated/malformed packets */
 123         if (ntohs(hdr->len) > udplen || ntohs(hdr->len) < sizeof(*hdr)) {
 124                 if (LOG_INVALID(IPPROTO_UDP))
 125                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 126                                 "nf_ct_udp: truncated/malformed packet ");
 127                 return -NF_ACCEPT;
 128         }
 129
 130         /* Packet with no checksum */
 131         if (!hdr->check)
 132                 return NF_ACCEPT;
 133
 134         /* Checksum invalid? Ignore.
 135          * We skip checking packets on the outgoing path
 136          * because the checksum is assumed to be correct.
 137          * FIXME: Source route IP option packets --RR */
 138         if (nf_conntrack_checksum &&
 139             ((pf == PF_INET && hooknum == NF_IP_PRE_ROUTING) ||
 140              (pf == PF_INET6 && hooknum == NF_IP6_PRE_ROUTING)) &&
 141             nf_checksum(skb, hooknum, dataoff, IPPROTO_UDP, pf)) {
 142                 if (LOG_INVALID(IPPROTO_UDP))
 143                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 144                                 "nf_ct_udp: bad UDP checksum ");
 145                 return -NF_ACCEPT;
 146         }
 147
 148         return NF_ACCEPT;
 149 }
 150
 151 #ifdef CONFIG_SYSCTL
 152 static unsigned int udp_sysctl_table_users;
 153 static struct ctl_table_header *udp_sysctl_header;
 154 static struct ctl_table udp_sysctl_table[] = {
 155         {
 156                 .ctl_name       = NET_NF_CONNTRACK_UDP_TIMEOUT,
 157                 .procname       = "nf_conntrack_udp_timeout",
 158                 .data           = &nf_ct_udp_timeout,
 159                 .maxlen         = sizeof(unsigned int),
 160                 .mode           = 0644,
 161                 .proc_handler   = &proc_dointvec_jiffies,
 162         },
 163         {
 164                 .ctl_name       = NET_NF_CONNTRACK_UDP_TIMEOUT_STREAM,
 165                 .procname       = "nf_conntrack_udp_timeout_stream",
 166                 .data           = &nf_ct_udp_timeout_stream,
 167                 .maxlen         = sizeof(unsigned int),
 168                 .mode           = 0644,
 169                 .proc_handler   = &proc_dointvec_jiffies,
 170         },
 171         {
 172                 .ctl_name       = 0
 173         }
 174 };
 175 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
 176 static struct ctl_table udp_compat_sysctl_table[] = {
 177         {
 178                 .ctl_name       = NET_IPV4_NF_CONNTRACK_UDP_TIMEOUT,
 179                 .procname       = "ip_conntrack_udp_timeout",
 180                 .data           = &nf_ct_udp_timeout,
 181                 .maxlen         = sizeof(unsigned int),
 182                 .mode           = 0644,
 183                 .proc_handler   = &proc_dointvec_jiffies,
 184         },
 185         {
 186                 .ctl_name       = NET_IPV4_NF_CONNTRACK_UDP_TIMEOUT_STREAM,
 187                 .procname       = "ip_conntrack_udp_timeout_stream",
 188                 .data           = &nf_ct_udp_timeout_stream,
 189                 .maxlen         = sizeof(unsigned int),
 190                 .mode           = 0644,
 191                 .proc_handler   = &proc_dointvec_jiffies,
 192         },
 193         {
 194                 .ctl_name       = 0
 195         }
 196 };
 197 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
 198 #endif /* CONFIG_SYSCTL */
 199
 200 struct nf_conntrack_l4proto nf_conntrack_l4proto_udp4 =
 201 {
 202         .l3proto                = PF_INET,
 203         .l4proto                = IPPROTO_UDP,
 204         .name                   = "udp",
 205         .pkt_to_tuple           = udp_pkt_to_tuple,
 206         .invert_tuple           = udp_invert_tuple,
 207         .print_tuple            = udp_print_tuple,
 208         .print_conntrack        = udp_print_conntrack,
 209         .packet                 = udp_packet,
 210         .new                    = udp_new,
 211         .error                  = udp_error,
 212 #if defined(CONFIG_NF_CT_NETLINK) || \
 213     defined(CONFIG_NF_CT_NETLINK_MODULE)
 214         .tuple_to_nfattr        = nf_ct_port_tuple_to_nfattr,
 215         .nfattr_to_tuple        = nf_ct_port_nfattr_to_tuple,
 216 #endif
 217 #ifdef CONFIG_SYSCTL
 218         .ctl_table_users        = &udp_sysctl_table_users,
 219         .ctl_table_header       = &udp_sysctl_header,
 220         .ctl_table              = udp_sysctl_table,
 221 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
 222         .ctl_compat_table       = udp_compat_sysctl_table,
 223 #endif
 224 #endif
 225 };
 226 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_udp4);
 227
 228 struct nf_conntrack_l4proto nf_conntrack_l4proto_udp6 =
 229 {
 230         .l3proto                = PF_INET6,
 231         .l4proto                = IPPROTO_UDP,
 232         .name                   = "udp",
 233         .pkt_to_tuple           = udp_pkt_to_tuple,
 234         .invert_tuple           = udp_invert_tuple,
 235         .print_tuple            = udp_print_tuple,
 236         .print_conntrack        = udp_print_conntrack,
 237         .packet                 = udp_packet,
 238         .new                    = udp_new,
 239         .error                  = udp_error,
 240 #if defined(CONFIG_NF_CT_NETLINK) || \
 241     defined(CONFIG_NF_CT_NETLINK_MODULE)
 242         .tuple_to_nfattr        = nf_ct_port_tuple_to_nfattr,
 243         .nfattr_to_tuple        = nf_ct_port_nfattr_to_tuple,
 244 #endif
 245 #ifdef CONFIG_SYSCTL
 246         .ctl_table_users        = &udp_sysctl_table_users,
 247         .ctl_table_header       = &udp_sysctl_header,
 248         .ctl_table              = udp_sysctl_table,
 249 #endif
 250 };
 251 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_udp6);