net/netfilter/nf_conntrack_proto_udplite.c

   1 /* (C) 1999-2001 Paul `Rusty' Russell
   2  * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
   3  * (C) 2007 Patrick McHardy <kaber@trash.net>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License version 2 as
   7  * published by the Free Software Foundation.
   8  */
   9
  10 #include <linux/types.h>
  11 #include <linux/timer.h>
  12 #include <linux/module.h>
  13 #include <linux/udp.h>
  14 #include <linux/seq_file.h>
  15 #include <linux/skbuff.h>
  16 #include <linux/ipv6.h>
  17 #include <net/ip6_checksum.h>
  18 #include <net/checksum.h>
  19
  20 #include <linux/netfilter.h>
  21 #include <linux/netfilter_ipv4.h>
  22 #include <linux/netfilter_ipv6.h>
  23 #include <net/netfilter/nf_conntrack_l4proto.h>
  24 #include <net/netfilter/nf_conntrack_ecache.h>
  25 #include <net/netfilter/nf_log.h>
  26
  27 static unsigned int nf_ct_udplite_timeout __read_mostly = 30*HZ;
  28 static unsigned int nf_ct_udplite_timeout_stream __read_mostly = 180*HZ;
  29
  30 static bool udplite_pkt_to_tuple(const struct sk_buff *skb,
  31                                  unsigned int dataoff,
  32                                  struct nf_conntrack_tuple *tuple)
  33 {
  34         const struct udphdr *hp;
  35         struct udphdr _hdr;
  36
  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         return true;
  44 }
  45
  46 static bool udplite_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 true;
  52 }
  53
  54 /* Print out the per-protocol part of the tuple. */
  55 static int udplite_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 udplite_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,
  75                                    nf_ct_udplite_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_udplite_timeout);
  81
  82         return NF_ACCEPT;
  83 }
  84
  85 /* Called when a new connection for this protocol found. */
  86 static bool udplite_new(struct nf_conn *ct, const struct sk_buff *skb,
  87                         unsigned int dataoff)
  88 {
  89         return true;
  90 }
  91
  92 static int udplite_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         unsigned int cscov;
 101
 102         /* Header is too small? */
 103         hdr = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
 104         if (hdr == NULL) {
 105                 if (LOG_INVALID(IPPROTO_UDPLITE))
 106                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 107                                       "nf_ct_udplite: short packet ");
 108                 return -NF_ACCEPT;
 109         }
 110
 111         cscov = ntohs(hdr->len);
 112         if (cscov == 0)
 113                 cscov = udplen;
 114         else if (cscov < sizeof(*hdr) || cscov > udplen) {
 115                 if (LOG_INVALID(IPPROTO_UDPLITE))
 116                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 117                                 "nf_ct_udplite: invalid checksum coverage ");
 118                 return -NF_ACCEPT;
 119         }
 120
 121         /* UDPLITE mandates checksums */
 122         if (!hdr->check) {
 123                 if (LOG_INVALID(IPPROTO_UDPLITE))
 124                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 125                                       "nf_ct_udplite: checksum missing ");
 126                 return -NF_ACCEPT;
 127         }
 128
 129         /* Checksum invalid? Ignore. */
 130         if (nf_conntrack_checksum && hooknum == NF_INET_PRE_ROUTING &&
 131             nf_checksum_partial(skb, hooknum, dataoff, cscov, IPPROTO_UDP,
 132                                 pf)) {
 133                 if (LOG_INVALID(IPPROTO_UDPLITE))
 134                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 135                                       "nf_ct_udplite: bad UDPLite checksum ");
 136                 return -NF_ACCEPT;
 137         }
 138
 139         return NF_ACCEPT;
 140 }
 141
 142 #ifdef CONFIG_SYSCTL
 143 static unsigned int udplite_sysctl_table_users;
 144 static struct ctl_table_header *udplite_sysctl_header;
 145 static struct ctl_table udplite_sysctl_table[] = {
 146         {
 147                 .ctl_name       = CTL_UNNUMBERED,
 148                 .procname       = "nf_conntrack_udplite_timeout",
 149                 .data           = &nf_ct_udplite_timeout,
 150                 .maxlen         = sizeof(unsigned int),
 151                 .mode           = 0644,
 152                 .proc_handler   = &proc_dointvec_jiffies,
 153         },
 154         {
 155                 .ctl_name       = CTL_UNNUMBERED,
 156                 .procname       = "nf_conntrack_udplite_timeout_stream",
 157                 .data           = &nf_ct_udplite_timeout_stream,
 158                 .maxlen         = sizeof(unsigned int),
 159                 .mode           = 0644,
 160                 .proc_handler   = &proc_dointvec_jiffies,
 161         },
 162         {
 163                 .ctl_name       = 0
 164         }
 165 };
 166 #endif /* CONFIG_SYSCTL */
 167
 168 static struct nf_conntrack_l4proto nf_conntrack_l4proto_udplite4 __read_mostly =
 169 {
 170         .l3proto                = PF_INET,
 171         .l4proto                = IPPROTO_UDPLITE,
 172         .name                   = "udplite",
 173         .pkt_to_tuple           = udplite_pkt_to_tuple,
 174         .invert_tuple           = udplite_invert_tuple,
 175         .print_tuple            = udplite_print_tuple,
 176         .packet                 = udplite_packet,
 177         .new                    = udplite_new,
 178         .error                  = udplite_error,
 179 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
 180         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
 181         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
 182         .nla_policy             = nf_ct_port_nla_policy,
 183 #endif
 184 #ifdef CONFIG_SYSCTL
 185         .ctl_table_users        = &udplite_sysctl_table_users,
 186         .ctl_table_header       = &udplite_sysctl_header,
 187         .ctl_table              = udplite_sysctl_table,
 188 #endif
 189 };
 190
 191 static struct nf_conntrack_l4proto nf_conntrack_l4proto_udplite6 __read_mostly =
 192 {
 193         .l3proto                = PF_INET6,
 194         .l4proto                = IPPROTO_UDPLITE,
 195         .name                   = "udplite",
 196         .pkt_to_tuple           = udplite_pkt_to_tuple,
 197         .invert_tuple           = udplite_invert_tuple,
 198         .print_tuple            = udplite_print_tuple,
 199         .packet                 = udplite_packet,
 200         .new                    = udplite_new,
 201         .error                  = udplite_error,
 202 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
 203         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
 204         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
 205         .nla_policy             = nf_ct_port_nla_policy,
 206 #endif
 207 #ifdef CONFIG_SYSCTL
 208         .ctl_table_users        = &udplite_sysctl_table_users,
 209         .ctl_table_header       = &udplite_sysctl_header,
 210         .ctl_table              = udplite_sysctl_table,
 211 #endif
 212 };
 213
 214 static int __init nf_conntrack_proto_udplite_init(void)
 215 {
 216         int err;
 217
 218         err = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_udplite4);
 219         if (err < 0)
 220                 goto err1;
 221         err = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_udplite6);
 222         if (err < 0)
 223                 goto err2;
 224         return 0;
 225 err2:
 226         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_udplite4);
 227 err1:
 228         return err;
 229 }
 230
 231 static void __exit nf_conntrack_proto_udplite_exit(void)
 232 {
 233         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_udplite6);
 234         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_udplite4);
 235 }
 236
 237 module_init(nf_conntrack_proto_udplite_init);
 238 module_exit(nf_conntrack_proto_udplite_exit);
 239
 240 MODULE_LICENSE("GPL");