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 #include <net/netfilter/ipv4/nf_conntrack_ipv4.h>
  26 #include <net/netfilter/ipv6/nf_conntrack_ipv6.h>
  27
  28 static unsigned int nf_ct_udp_timeout __read_mostly = 30*HZ;
  29 static unsigned int nf_ct_udp_timeout_stream __read_mostly = 180*HZ;
  30
  31 static bool udp_pkt_to_tuple(const struct sk_buff *skb,
  32                              unsigned int dataoff,
  33                              struct nf_conntrack_tuple *tuple)
  34 {
  35         const struct udphdr *hp;
  36         struct udphdr _hdr;
  37
  38         /* Actually only need first 8 bytes. */
  39         hp = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
  40         if (hp == NULL)
  41                 return false;
  42
  43         tuple->src.u.udp.port = hp->source;
  44         tuple->dst.u.udp.port = hp->dest;
  45
  46         return true;
  47 }
  48
  49 static bool udp_invert_tuple(struct nf_conntrack_tuple *tuple,
  50                              const struct nf_conntrack_tuple *orig)
  51 {
  52         tuple->src.u.udp.port = orig->dst.u.udp.port;
  53         tuple->dst.u.udp.port = orig->src.u.udp.port;
  54         return true;
  55 }
  56
  57 /* Print out the per-protocol part of the tuple. */
  58 static int udp_print_tuple(struct seq_file *s,
  59                            const struct nf_conntrack_tuple *tuple)
  60 {
  61         return seq_printf(s, "sport=%hu dport=%hu ",
  62                           ntohs(tuple->src.u.udp.port),
  63                           ntohs(tuple->dst.u.udp.port));
  64 }
  65
  66 /* Returns verdict for packet, and may modify conntracktype */
  67 static int udp_packet(struct nf_conn *ct,
  68                       const struct sk_buff *skb,
  69                       unsigned int dataoff,
  70                       enum ip_conntrack_info ctinfo,
  71                       u_int8_t pf,
  72                       unsigned int hooknum)
  73 {
  74         /* If we've seen traffic both ways, this is some kind of UDP
  75            stream.  Extend timeout. */
  76         if (test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
  77                 nf_ct_refresh_acct(ct, ctinfo, skb, nf_ct_udp_timeout_stream);
  78                 /* Also, more likely to be important, and not a probe */
  79                 if (!test_and_set_bit(IPS_ASSURED_BIT, &ct->status))
  80                         nf_conntrack_event_cache(IPCT_ASSURED, ct);
  81         } else
  82                 nf_ct_refresh_acct(ct, ctinfo, skb, nf_ct_udp_timeout);
  83
  84         return NF_ACCEPT;
  85 }
  86
  87 /* Called when a new connection for this protocol found. */
  88 static bool udp_new(struct nf_conn *ct, const struct sk_buff *skb,
  89                     unsigned int dataoff)
  90 {
  91         return true;
  92 }
  93
  94 static int udp_error(struct net *net, struct nf_conn *tmpl, struct sk_buff *skb,
  95                      unsigned int dataoff, enum ip_conntrack_info *ctinfo,
  96                      u_int8_t pf,
  97                      unsigned int hooknum)
  98 {
  99         unsigned int udplen = skb->len - dataoff;
 100         const struct udphdr *hdr;
 101         struct udphdr _hdr;
 102
 103         /* Header is too small? */
 104         hdr = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
 105         if (hdr == NULL) {
 106                 if (LOG_INVALID(net, IPPROTO_UDP))
 107                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 108                                       "nf_ct_udp: short packet ");
 109                 return -NF_ACCEPT;
 110         }
 111
 112         /* Truncated/malformed packets */
 113         if (ntohs(hdr->len) > udplen || ntohs(hdr->len) < sizeof(*hdr)) {
 114                 if (LOG_INVALID(net, IPPROTO_UDP))
 115                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 116                                 "nf_ct_udp: truncated/malformed packet ");
 117                 return -NF_ACCEPT;
 118         }
 119
 120         /* Packet with no checksum */
 121         if (!hdr->check)
 122                 return NF_ACCEPT;
 123
 124         /* Checksum invalid? Ignore.
 125          * We skip checking packets on the outgoing path
 126          * because the checksum is assumed to be correct.
 127          * FIXME: Source route IP option packets --RR */
 128         if (net->ct.sysctl_checksum && hooknum == NF_INET_PRE_ROUTING &&
 129             nf_checksum(skb, hooknum, dataoff, IPPROTO_UDP, pf)) {
 130                 if (LOG_INVALID(net, IPPROTO_UDP))
 131                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 132                                 "nf_ct_udp: bad UDP checksum ");
 133                 return -NF_ACCEPT;
 134         }
 135
 136         return NF_ACCEPT;
 137 }
 138
 139 #ifdef CONFIG_SYSCTL
 140 static unsigned int udp_sysctl_table_users;
 141 static struct ctl_table_header *udp_sysctl_header;
 142 static struct ctl_table udp_sysctl_table[] = {
 143         {
 144                 .procname       = "nf_conntrack_udp_timeout",
 145                 .data           = &nf_ct_udp_timeout,
 146                 .maxlen         = sizeof(unsigned int),
 147                 .mode           = 0644,
 148                 .proc_handler   = proc_dointvec_jiffies,
 149         },
 150         {
 151                 .procname       = "nf_conntrack_udp_timeout_stream",
 152                 .data           = &nf_ct_udp_timeout_stream,
 153                 .maxlen         = sizeof(unsigned int),
 154                 .mode           = 0644,
 155                 .proc_handler   = proc_dointvec_jiffies,
 156         },
 157         { }
 158 };
 159 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
 160 static struct ctl_table udp_compat_sysctl_table[] = {
 161         {
 162                 .procname       = "ip_conntrack_udp_timeout",
 163                 .data           = &nf_ct_udp_timeout,
 164                 .maxlen         = sizeof(unsigned int),
 165                 .mode           = 0644,
 166                 .proc_handler   = proc_dointvec_jiffies,
 167         },
 168         {
 169                 .procname       = "ip_conntrack_udp_timeout_stream",
 170                 .data           = &nf_ct_udp_timeout_stream,
 171                 .maxlen         = sizeof(unsigned int),
 172                 .mode           = 0644,
 173                 .proc_handler   = proc_dointvec_jiffies,
 174         },
 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         .nlattr_tuple_size      = nf_ct_port_nlattr_tuple_size,
 195         .nla_policy             = nf_ct_port_nla_policy,
 196 #endif
 197 #ifdef CONFIG_SYSCTL
 198         .ctl_table_users        = &udp_sysctl_table_users,
 199         .ctl_table_header       = &udp_sysctl_header,
 200         .ctl_table              = udp_sysctl_table,
 201 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
 202         .ctl_compat_table       = udp_compat_sysctl_table,
 203 #endif
 204 #endif
 205 };
 206 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_udp4);
 207
 208 struct nf_conntrack_l4proto nf_conntrack_l4proto_udp6 __read_mostly =
 209 {
 210         .l3proto                = PF_INET6,
 211         .l4proto                = IPPROTO_UDP,
 212         .name                   = "udp",
 213         .pkt_to_tuple           = udp_pkt_to_tuple,
 214         .invert_tuple           = udp_invert_tuple,
 215         .print_tuple            = udp_print_tuple,
 216         .packet                 = udp_packet,
 217         .new                    = udp_new,
 218         .error                  = udp_error,
 219 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
 220         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
 221         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
 222         .nlattr_tuple_size      = nf_ct_port_nlattr_tuple_size,
 223         .nla_policy             = nf_ct_port_nla_policy,
 224 #endif
 225 #ifdef CONFIG_SYSCTL
 226         .ctl_table_users        = &udp_sysctl_table_users,
 227         .ctl_table_header       = &udp_sysctl_header,
 228         .ctl_table              = udp_sysctl_table,
 229 #endif
 230 };
 231 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_udp6);