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