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