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/netfilter.h>
  14 #include <linux/udp.h>
  15 #include <linux/seq_file.h>
  16 #include <linux/skbuff.h>
  17 #include <linux/ipv6.h>
  18 #include <net/ip6_checksum.h>
  19 #include <net/checksum.h>
  20
  21 #include <linux/netfilter.h>
  22 #include <linux/netfilter_ipv4.h>
  23 #include <linux/netfilter_ipv6.h>
  24 #include <net/netfilter/nf_conntrack_l4proto.h>
  25 #include <net/netfilter/nf_conntrack_ecache.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 /* Print out the private part of the conntrack. */
  63 static int udplite_print_conntrack(struct seq_file *s,
  64                                    const struct nf_conn *conntrack)
  65 {
  66         return 0;
  67 }
  68
  69 /* Returns verdict for packet, and may modify conntracktype */
  70 static int udplite_packet(struct nf_conn *conntrack,
  71                           const struct sk_buff *skb,
  72                           unsigned int dataoff,
  73                           enum ip_conntrack_info ctinfo,
  74                           int pf,
  75                           unsigned int hooknum)
  76 {
  77         /* If we've seen traffic both ways, this is some kind of UDP
  78            stream.  Extend timeout. */
  79         if (test_bit(IPS_SEEN_REPLY_BIT, &conntrack->status)) {
  80                 nf_ct_refresh_acct(conntrack, ctinfo, skb,
  81                                    nf_ct_udplite_timeout_stream);
  82                 /* Also, more likely to be important, and not a probe */
  83                 if (!test_and_set_bit(IPS_ASSURED_BIT, &conntrack->status))
  84                         nf_conntrack_event_cache(IPCT_STATUS, skb);
  85         } else
  86                 nf_ct_refresh_acct(conntrack, ctinfo, skb,
  87                                    nf_ct_udplite_timeout);
  88
  89         return NF_ACCEPT;
  90 }
  91
  92 /* Called when a new connection for this protocol found. */
  93 static int udplite_new(struct nf_conn *conntrack, const struct sk_buff *skb,
  94                        unsigned int dataoff)
  95 {
  96         return 1;
  97 }
  98
  99 static int udplite_error(struct sk_buff *skb, unsigned int dataoff,
 100                          enum ip_conntrack_info *ctinfo,
 101                          int pf,
 102                          unsigned int hooknum)
 103 {
 104         unsigned int udplen = skb->len - dataoff;
 105         struct udphdr _hdr, *hdr;
 106         unsigned int cscov;
 107
 108         /* Header is too small? */
 109         hdr = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
 110         if (hdr == NULL) {
 111                 if (LOG_INVALID(IPPROTO_UDPLITE))
 112                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 113                                       "nf_ct_udplite: short packet ");
 114                 return -NF_ACCEPT;
 115         }
 116
 117         cscov = ntohs(hdr->len);
 118         if (cscov == 0)
 119                 cscov = udplen;
 120         else if (cscov < sizeof(*hdr) || cscov > udplen) {
 121                 if (LOG_INVALID(IPPROTO_UDPLITE))
 122                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 123                                 "nf_ct_udplite: invalid checksum coverage ");
 124                 return -NF_ACCEPT;
 125         }
 126
 127         /* UDPLITE mandates checksums */
 128         if (!hdr->check) {
 129                 if (LOG_INVALID(IPPROTO_UDPLITE))
 130                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 131                                       "nf_ct_udplite: checksum missing ");
 132                 return -NF_ACCEPT;
 133         }
 134
 135         /* Checksum invalid? Ignore. */
 136         if (nf_conntrack_checksum && !skb_csum_unnecessary(skb) &&
 137             ((pf == PF_INET && hooknum == NF_IP_PRE_ROUTING) ||
 138              (pf == PF_INET6 && hooknum == NF_IP6_PRE_ROUTING))) {
 139                 if (pf == PF_INET) {
 140                         struct iphdr *iph = ip_hdr(skb);
 141
 142                         skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr,
 143                                                        udplen, IPPROTO_UDPLITE, 0);
 144                 } else {
 145                         struct ipv6hdr *ipv6h = ipv6_hdr(skb);
 146                         __wsum hsum = skb_checksum(skb, 0, dataoff, 0);
 147
 148                         skb->csum = ~csum_unfold(
 149                                 csum_ipv6_magic(&ipv6h->saddr, &ipv6h->daddr,
 150                                                 udplen, IPPROTO_UDPLITE,
 151                                                 csum_sub(0, hsum)));
 152                 }
 153
 154                 skb->ip_summed = CHECKSUM_NONE;
 155                 if (__skb_checksum_complete_head(skb, dataoff + cscov)) {
 156                         if (LOG_INVALID(IPPROTO_UDPLITE))
 157                                 nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 158                                               "nf_ct_udplite: bad UDPLite "
 159                                               "checksum ");
 160                         return -NF_ACCEPT;
 161                 }
 162                 skb->ip_summed = CHECKSUM_UNNECESSARY;
 163         }
 164
 165         return NF_ACCEPT;
 166 }
 167
 168 #ifdef CONFIG_SYSCTL
 169 static unsigned int udplite_sysctl_table_users;
 170 static struct ctl_table_header *udplite_sysctl_header;
 171 static struct ctl_table udplite_sysctl_table[] = {
 172         {
 173                 .ctl_name       = CTL_UNNUMBERED,
 174                 .procname       = "nf_conntrack_udplite_timeout",
 175                 .data           = &nf_ct_udplite_timeout,
 176                 .maxlen         = sizeof(unsigned int),
 177                 .mode           = 0644,
 178                 .proc_handler   = &proc_dointvec_jiffies,
 179         },
 180         {
 181                 .ctl_name       = CTL_UNNUMBERED,
 182                 .procname       = "nf_conntrack_udplite_timeout_stream",
 183                 .data           = &nf_ct_udplite_timeout_stream,
 184                 .maxlen         = sizeof(unsigned int),
 185                 .mode           = 0644,
 186                 .proc_handler   = &proc_dointvec_jiffies,
 187         },
 188         {
 189                 .ctl_name       = 0
 190         }
 191 };
 192 #endif /* CONFIG_SYSCTL */
 193
 194 static struct nf_conntrack_l4proto nf_conntrack_l4proto_udplite4 __read_mostly =
 195 {
 196         .l3proto                = PF_INET,
 197         .l4proto                = IPPROTO_UDPLITE,
 198         .name                   = "udplite",
 199         .pkt_to_tuple           = udplite_pkt_to_tuple,
 200         .invert_tuple           = udplite_invert_tuple,
 201         .print_tuple            = udplite_print_tuple,
 202         .print_conntrack        = udplite_print_conntrack,
 203         .packet                 = udplite_packet,
 204         .new                    = udplite_new,
 205         .error                  = udplite_error,
 206 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
 207         .tuple_to_nfattr        = nf_ct_port_tuple_to_nfattr,
 208         .nfattr_to_tuple        = nf_ct_port_nfattr_to_tuple,
 209 #endif
 210 #ifdef CONFIG_SYSCTL
 211         .ctl_table_users        = &udplite_sysctl_table_users,
 212         .ctl_table_header       = &udplite_sysctl_header,
 213         .ctl_table              = udplite_sysctl_table,
 214 #endif
 215 };
 216
 217 static struct nf_conntrack_l4proto nf_conntrack_l4proto_udplite6 __read_mostly =
 218 {
 219         .l3proto                = PF_INET6,
 220         .l4proto                = IPPROTO_UDPLITE,
 221         .name                   = "udplite",
 222         .pkt_to_tuple           = udplite_pkt_to_tuple,
 223         .invert_tuple           = udplite_invert_tuple,
 224         .print_tuple            = udplite_print_tuple,
 225         .print_conntrack        = udplite_print_conntrack,
 226         .packet                 = udplite_packet,
 227         .new                    = udplite_new,
 228         .error                  = udplite_error,
 229 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
 230         .tuple_to_nfattr        = nf_ct_port_tuple_to_nfattr,
 231         .nfattr_to_tuple        = nf_ct_port_nfattr_to_tuple,
 232 #endif
 233 #ifdef CONFIG_SYSCTL
 234         .ctl_table_users        = &udplite_sysctl_table_users,
 235         .ctl_table_header       = &udplite_sysctl_header,
 236         .ctl_table              = udplite_sysctl_table,
 237 #endif
 238 };
 239
 240 static int __init nf_conntrack_proto_udplite_init(void)
 241 {
 242         int err;
 243
 244         err = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_udplite4);
 245         if (err < 0)
 246                 goto err1;
 247         err = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_udplite6);
 248         if (err < 0)
 249                 goto err2;
 250         return 0;
 251 err2:
 252         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_udplite4);
 253 err1:
 254         return err;
 255 }
 256
 257 static void __exit nf_conntrack_proto_udplite_exit(void)
 258 {
 259         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_udplite6);
 260         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_udplite4);
 261 }
 262
 263 module_init(nf_conntrack_proto_udplite_init);
 264 module_exit(nf_conntrack_proto_udplite_exit);
 265
 266 MODULE_LICENSE("GPL");