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   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/timer.h>
  11 #include <linux/module.h>
  12 #include <linux/udp.h>
  13 #include <linux/seq_file.h>
  14 #include <linux/skbuff.h>
  15 #include <linux/ipv6.h>
  16 #include <net/ip6_checksum.h>
  17 #include <net/checksum.h>
  18
  19 #include <linux/netfilter.h>
  20 #include <linux/netfilter_ipv4.h>
  21 #include <linux/netfilter_ipv6.h>
  22 #include <net/netfilter/nf_conntrack_l4proto.h>
  23 #include <net/netfilter/nf_conntrack_ecache.h>
  24
  25 static unsigned int nf_ct_udp_timeout __read_mostly = 30*HZ;
  26 static unsigned int nf_ct_udp_timeout_stream __read_mostly = 180*HZ;
  27
  28 static int udp_pkt_to_tuple(const struct sk_buff *skb,
  29                              unsigned int dataoff,
  30                              struct nf_conntrack_tuple *tuple)
  31 {
  32         struct udphdr _hdr, *hp;
  33
  34         /* Actually only need first 8 bytes. */
  35         hp = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
  36         if (hp == NULL)
  37                 return 0;
  38
  39         tuple->src.u.udp.port = hp->source;
  40         tuple->dst.u.udp.port = hp->dest;
  41
  42         return 1;
  43 }
  44
  45 static int udp_invert_tuple(struct nf_conntrack_tuple *tuple,
  46                             const struct nf_conntrack_tuple *orig)
  47 {
  48         tuple->src.u.udp.port = orig->dst.u.udp.port;
  49         tuple->dst.u.udp.port = orig->src.u.udp.port;
  50         return 1;
  51 }
  52
  53 /* Print out the per-protocol part of the tuple. */
  54 static int udp_print_tuple(struct seq_file *s,
  55                            const struct nf_conntrack_tuple *tuple)
  56 {
  57         return seq_printf(s, "sport=%hu dport=%hu ",
  58                           ntohs(tuple->src.u.udp.port),
  59                           ntohs(tuple->dst.u.udp.port));
  60 }
  61
  62 /* Print out the private part of the conntrack. */
  63 static int udp_print_conntrack(struct seq_file *s,
  64                                const struct nf_conn *conntrack)
  65 {
  66         return 0;
  67 }
  68
  69 /* Returns verdict for packet, and may modify conntracktype */
  70 static int udp_packet(struct nf_conn *conntrack,
  71                       const struct sk_buff *skb,
  72                       unsigned int dataoff,
  73                       enum ip_conntrack_info ctinfo,
  74                       int pf,
  75                       unsigned int hooknum)
  76 {
  77         /* If we've seen traffic both ways, this is some kind of UDP
  78            stream.  Extend timeout. */
  79         if (test_bit(IPS_SEEN_REPLY_BIT, &conntrack->status)) {
  80                 nf_ct_refresh_acct(conntrack, ctinfo, skb,
  81                                    nf_ct_udp_timeout_stream);
  82                 /* Also, more likely to be important, and not a probe */
  83                 if (!test_and_set_bit(IPS_ASSURED_BIT, &conntrack->status))
  84                         nf_conntrack_event_cache(IPCT_STATUS, skb);
  85         } else
  86                 nf_ct_refresh_acct(conntrack, ctinfo, skb, nf_ct_udp_timeout);
  87
  88         return NF_ACCEPT;
  89 }
  90
  91 /* Called when a new connection for this protocol found. */
  92 static int udp_new(struct nf_conn *conntrack, const struct sk_buff *skb,
  93                    unsigned int dataoff)
  94 {
  95         return 1;
  96 }
  97
  98 static int udp_error(struct sk_buff *skb, unsigned int dataoff,
  99                      enum ip_conntrack_info *ctinfo,
 100                      int pf,
 101                      unsigned int hooknum)
 102 {
 103         unsigned int udplen = skb->len - dataoff;
 104         struct udphdr _hdr, *hdr;
 105
 106         /* Header is too small? */
 107         hdr = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
 108         if (hdr == NULL) {
 109                 if (LOG_INVALID(IPPROTO_UDP))
 110                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 111                                       "nf_ct_udp: short packet ");
 112                 return -NF_ACCEPT;
 113         }
 114
 115         /* Truncated/malformed packets */
 116         if (ntohs(hdr->len) > udplen || ntohs(hdr->len) < sizeof(*hdr)) {
 117                 if (LOG_INVALID(IPPROTO_UDP))
 118                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 119                                 "nf_ct_udp: truncated/malformed packet ");
 120                 return -NF_ACCEPT;
 121         }
 122
 123         /* Packet with no checksum */
 124         if (!hdr->check)
 125                 return NF_ACCEPT;
 126
 127         /* Checksum invalid? Ignore.
 128          * We skip checking packets on the outgoing path
 129          * because the checksum is assumed to be correct.
 130          * FIXME: Source route IP option packets --RR */
 131         if (nf_conntrack_checksum && hooknum == NF_INET_PRE_ROUTING &&
 132             nf_checksum(skb, hooknum, dataoff, IPPROTO_UDP, pf)) {
 133                 if (LOG_INVALID(IPPROTO_UDP))
 134                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 135                                 "nf_ct_udp: bad UDP checksum ");
 136                 return -NF_ACCEPT;
 137         }
 138
 139         return NF_ACCEPT;
 140 }
 141
 142 #ifdef CONFIG_SYSCTL
 143 static unsigned int udp_sysctl_table_users;
 144 static struct ctl_table_header *udp_sysctl_header;
 145 static struct ctl_table udp_sysctl_table[] = {
 146         {
 147                 .procname       = "nf_conntrack_udp_timeout",
 148                 .data           = &nf_ct_udp_timeout,
 149                 .maxlen         = sizeof(unsigned int),
 150                 .mode           = 0644,
 151                 .proc_handler   = &proc_dointvec_jiffies,
 152         },
 153         {
 154                 .procname       = "nf_conntrack_udp_timeout_stream",
 155                 .data           = &nf_ct_udp_timeout_stream,
 156                 .maxlen         = sizeof(unsigned int),
 157                 .mode           = 0644,
 158                 .proc_handler   = &proc_dointvec_jiffies,
 159         },
 160         {
 161                 .ctl_name       = 0
 162         }
 163 };
 164 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
 165 static struct ctl_table udp_compat_sysctl_table[] = {
 166         {
 167                 .procname       = "ip_conntrack_udp_timeout",
 168                 .data           = &nf_ct_udp_timeout,
 169                 .maxlen         = sizeof(unsigned int),
 170                 .mode           = 0644,
 171                 .proc_handler   = &proc_dointvec_jiffies,
 172         },
 173         {
 174                 .procname       = "ip_conntrack_udp_timeout_stream",
 175                 .data           = &nf_ct_udp_timeout_stream,
 176                 .maxlen         = sizeof(unsigned int),
 177                 .mode           = 0644,
 178                 .proc_handler   = &proc_dointvec_jiffies,
 179         },
 180         {
 181                 .ctl_name       = 0
 182         }
 183 };
 184 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
 185 #endif /* CONFIG_SYSCTL */
 186
 187 struct nf_conntrack_l4proto nf_conntrack_l4proto_udp4 __read_mostly =
 188 {
 189         .l3proto                = PF_INET,
 190         .l4proto                = IPPROTO_UDP,
 191         .name                   = "udp",
 192         .pkt_to_tuple           = udp_pkt_to_tuple,
 193         .invert_tuple           = udp_invert_tuple,
 194         .print_tuple            = udp_print_tuple,
 195         .print_conntrack        = udp_print_conntrack,
 196         .packet                 = udp_packet,
 197         .new                    = udp_new,
 198         .error                  = udp_error,
 199 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
 200         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
 201         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
 202         .nla_policy             = nf_ct_port_nla_policy,
 203 #endif
 204 #ifdef CONFIG_SYSCTL
 205         .ctl_table_users        = &udp_sysctl_table_users,
 206         .ctl_table_header       = &udp_sysctl_header,
 207         .ctl_table              = udp_sysctl_table,
 208 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
 209         .ctl_compat_table       = udp_compat_sysctl_table,
 210 #endif
 211 #endif
 212 };
 213 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_udp4);
 214
 215 struct nf_conntrack_l4proto nf_conntrack_l4proto_udp6 __read_mostly =
 216 {
 217         .l3proto                = PF_INET6,
 218         .l4proto                = IPPROTO_UDP,
 219         .name                   = "udp",
 220         .pkt_to_tuple           = udp_pkt_to_tuple,
 221         .invert_tuple           = udp_invert_tuple,
 222         .print_tuple            = udp_print_tuple,
 223         .print_conntrack        = udp_print_conntrack,
 224         .packet                 = udp_packet,
 225         .new                    = udp_new,
 226         .error                  = udp_error,
 227 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
 228         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
 229         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
 230         .nla_policy             = nf_ct_port_nla_policy,
 231 #endif
 232 #ifdef CONFIG_SYSCTL
 233         .ctl_table_users        = &udp_sysctl_table_users,
 234         .ctl_table_header       = &udp_sysctl_header,
 235         .ctl_table              = udp_sysctl_table,
 236 #endif
 237 };
 238 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_udp6);