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 int udplite_pkt_to_tuple(const struct sk_buff *skb,
  31                                 unsigned int dataoff,
  32                                 struct nf_conntrack_tuple *tuple)
  33 {
  34         struct udphdr _hdr, *hp;
  35
  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         return 1;
  43 }
  44
  45 static int udplite_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 udplite_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 /* Returns verdict for packet, and may modify conntracktype */
  63 static int udplite_packet(struct nf_conn *conntrack,
  64                           const struct sk_buff *skb,
  65                           unsigned int dataoff,
  66                           enum ip_conntrack_info ctinfo,
  67                           int pf,
  68                           unsigned int hooknum)
  69 {
  70         /* If we've seen traffic both ways, this is some kind of UDP
  71            stream.  Extend timeout. */
  72         if (test_bit(IPS_SEEN_REPLY_BIT, &conntrack->status)) {
  73                 nf_ct_refresh_acct(conntrack, ctinfo, skb,
  74                                    nf_ct_udplite_timeout_stream);
  75                 /* Also, more likely to be important, and not a probe */
  76                 if (!test_and_set_bit(IPS_ASSURED_BIT, &conntrack->status))
  77                         nf_conntrack_event_cache(IPCT_STATUS, skb);
  78         } else
  79                 nf_ct_refresh_acct(conntrack, ctinfo, skb,
  80                                    nf_ct_udplite_timeout);
  81
  82         return NF_ACCEPT;
  83 }
  84
  85 /* Called when a new connection for this protocol found. */
  86 static int udplite_new(struct nf_conn *conntrack, const struct sk_buff *skb,
  87                        unsigned int dataoff)
  88 {
  89         return 1;
  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         struct udphdr _hdr, *hdr;
  99         unsigned int cscov;
 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_UDPLITE))
 105                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 106                                       "nf_ct_udplite: short packet ");
 107                 return -NF_ACCEPT;
 108         }
 109
 110         cscov = ntohs(hdr->len);
 111         if (cscov == 0)
 112                 cscov = udplen;
 113         else if (cscov < sizeof(*hdr) || cscov > udplen) {
 114                 if (LOG_INVALID(IPPROTO_UDPLITE))
 115                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 116                                 "nf_ct_udplite: invalid checksum coverage ");
 117                 return -NF_ACCEPT;
 118         }
 119
 120         /* UDPLITE mandates checksums */
 121         if (!hdr->check) {
 122                 if (LOG_INVALID(IPPROTO_UDPLITE))
 123                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 124                                       "nf_ct_udplite: checksum missing ");
 125                 return -NF_ACCEPT;
 126         }
 127
 128         /* Checksum invalid? Ignore. */
 129         if (nf_conntrack_checksum && !skb_csum_unnecessary(skb) &&
 130             hooknum == NF_INET_PRE_ROUTING) {
 131                 if (pf == PF_INET) {
 132                         struct iphdr *iph = ip_hdr(skb);
 133
 134                         skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr,
 135                                                        udplen, IPPROTO_UDPLITE, 0);
 136                 } else {
 137                         struct ipv6hdr *ipv6h = ipv6_hdr(skb);
 138                         __wsum hsum = skb_checksum(skb, 0, dataoff, 0);
 139
 140                         skb->csum = ~csum_unfold(
 141                                 csum_ipv6_magic(&ipv6h->saddr, &ipv6h->daddr,
 142                                                 udplen, IPPROTO_UDPLITE,
 143                                                 csum_sub(0, hsum)));
 144                 }
 145
 146                 skb->ip_summed = CHECKSUM_NONE;
 147                 if (__skb_checksum_complete_head(skb, dataoff + cscov)) {
 148                         if (LOG_INVALID(IPPROTO_UDPLITE))
 149                                 nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 150                                               "nf_ct_udplite: bad UDPLite "
 151                                               "checksum ");
 152                         return -NF_ACCEPT;
 153                 }
 154                 skb->ip_summed = CHECKSUM_UNNECESSARY;
 155         }
 156
 157         return NF_ACCEPT;
 158 }
 159
 160 #ifdef CONFIG_SYSCTL
 161 static unsigned int udplite_sysctl_table_users;
 162 static struct ctl_table_header *udplite_sysctl_header;
 163 static struct ctl_table udplite_sysctl_table[] = {
 164         {
 165                 .ctl_name       = CTL_UNNUMBERED,
 166                 .procname       = "nf_conntrack_udplite_timeout",
 167                 .data           = &nf_ct_udplite_timeout,
 168                 .maxlen         = sizeof(unsigned int),
 169                 .mode           = 0644,
 170                 .proc_handler   = &proc_dointvec_jiffies,
 171         },
 172         {
 173                 .ctl_name       = CTL_UNNUMBERED,
 174                 .procname       = "nf_conntrack_udplite_timeout_stream",
 175                 .data           = &nf_ct_udplite_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_SYSCTL */
 185
 186 static struct nf_conntrack_l4proto nf_conntrack_l4proto_udplite4 __read_mostly =
 187 {
 188         .l3proto                = PF_INET,
 189         .l4proto                = IPPROTO_UDPLITE,
 190         .name                   = "udplite",
 191         .pkt_to_tuple           = udplite_pkt_to_tuple,
 192         .invert_tuple           = udplite_invert_tuple,
 193         .print_tuple            = udplite_print_tuple,
 194         .packet                 = udplite_packet,
 195         .new                    = udplite_new,
 196         .error                  = udplite_error,
 197 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
 198         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
 199         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
 200         .nla_policy             = nf_ct_port_nla_policy,
 201 #endif
 202 #ifdef CONFIG_SYSCTL
 203         .ctl_table_users        = &udplite_sysctl_table_users,
 204         .ctl_table_header       = &udplite_sysctl_header,
 205         .ctl_table              = udplite_sysctl_table,
 206 #endif
 207 };
 208
 209 static struct nf_conntrack_l4proto nf_conntrack_l4proto_udplite6 __read_mostly =
 210 {
 211         .l3proto                = PF_INET6,
 212         .l4proto                = IPPROTO_UDPLITE,
 213         .name                   = "udplite",
 214         .pkt_to_tuple           = udplite_pkt_to_tuple,
 215         .invert_tuple           = udplite_invert_tuple,
 216         .print_tuple            = udplite_print_tuple,
 217         .packet                 = udplite_packet,
 218         .new                    = udplite_new,
 219         .error                  = udplite_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        = &udplite_sysctl_table_users,
 227         .ctl_table_header       = &udplite_sysctl_header,
 228         .ctl_table              = udplite_sysctl_table,
 229 #endif
 230 };
 231
 232 static int __init nf_conntrack_proto_udplite_init(void)
 233 {
 234         int err;
 235
 236         err = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_udplite4);
 237         if (err < 0)
 238                 goto err1;
 239         err = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_udplite6);
 240         if (err < 0)
 241                 goto err2;
 242         return 0;
 243 err2:
 244         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_udplite4);
 245 err1:
 246         return err;
 247 }
 248
 249 static void __exit nf_conntrack_proto_udplite_exit(void)
 250 {
 251         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_udplite6);
 252         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_udplite4);
 253 }
 254
 255 module_init(nf_conntrack_proto_udplite_init);
 256 module_exit(nf_conntrack_proto_udplite_exit);
 257
 258 MODULE_LICENSE("GPL");